Class Note for PSYC 302 at UA
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PSYC 302 Biopsychology 1 12707 Announcements 1 Review Sessiontoday 2 Final exam next Tues 124 Substance Abuse and Addiction Reward pathway Dopaminergic neurons have their cell bodies in the ventral tegmental area VTA and their axons extend into various brain areas including the nucleus accumbens The nucleus accumbens is part of a structure called the striatum that includes the caudate nucleus and putamen Although it39s a small structure it39s a very important quotpleasure centerquot Olds amp Milner stuck an electrode accidentally in a rat39s nucleus accumbens and they found that the rat would forego sleep and food to selfstimulate Alcohol From a psychopharmacological perspective alcohol inhibits the ow of sodium ions into neurons making it a CNS depressant Decreases serotonin excitatory activity and facilitates response by the GABA inhibitory receptors lt blocks glutamate excitatory receptors and increases dopamine excitatory key to the reward pathway activity Type I vs Type II Type is late onset and so it appears to be less genetic in basis and less severe than Type II which is largely genetic Type II alcoholism has greater concordance in monozygotic vs dizygotic twins Plus there is a strong correlation between the occurrence of Typ ll alcoholism in biological fathers and sons even when the son is adopted and raised in a nonalcoholic family One ofthe treatments for alcoholism is antabuse which has a low adherence rate The drug causes the user to become severely nauseated when they drink alcohol Alcohol metabolism alcohol gt acetaldehyde gt acetic acid Acetaldehyde is very toxic and causes nausea and vomiting Methadone in the treatment of heroin addiction Methadone is just a substitute opiate for heroin When taken orally it crosses the bloodbrain barrier much more slowly than heroin and so it produces its effects more slowly including withdrawal and it39s far less addictive BUT if you inject methadone it becomes pretty similar to heroin in its effects Solution Mix naloxone with methadone Naloxone is an antagonist that blocks opiate receptors But when it39s taken orally it39s broken down in the stomach and rendered ineffective If it39s taken in any other way it blocks the effects of methadone or any other opiate DEPRESSION Is there a genetic component There are two genes implicated in depression One gene results in lowered serotonin production and the other gene increases the efficiency of serotonin reuptake What are anatomicalstructural differences in the brains of depressed individuals Depressed people have less activity in the LEFT prefrontal cortex and more in the RIGHT Drug treatments 1 tricyclics eg Tofranil prevents the presynaptic neuron from reuptaking serotonin dopamine and norepinephrine 2 selective serotonin reuptake inhibitors SSRls eg Paxil Zoloft Prozac they block the reuptake of serotonin but not of other monoamines 3 Monoamine oxidase inhibitors Monoamines are a class of neurotransmitters that includes dopamine serotonin epinephrine and norepinephrine Monoamine oxidase MAO is an enzyme that breaks down these neurotransmitters By blocking MAO you leave the neurotransmitters in the synapse longer so that they exert a greater effect 4 atypical antidepressants Wellbutrine inhibits dopamine and norepinephrine reuptake Comparing different treatments for depression we see the following ef cacy rates Antidepressants 5060 Psychotherapy 5060 Placebo 30 Electroconvulsive therapy ECT as seen in quotOrdinary Peoplequot and quotOne Flew Overthe Cuckoo39s Nestquot Nobody knows exactly why it works It has certain side effects including memory loss which can be minimized by administering the current only to the right hemisphere and it has a high relapse rate Depressed people have sleep maintenance insomnia trouble getting back to sleep when they awaken and enter REM more quickly This suggests that they are quotphase advancedquot that their sleepwaking cycle has shifted so that their body temperature starts to decrease earlier in the day In some cases ifyou keep the patient awake for an entire night their sleepwaking cycle will return to normal and depression symptoms will decrease Seasonal Affective Disorder SAD phase delay in the sleepwaking cycle meaning that sleep occurs later and temperature rhythms are altered so that temperature decreases happen later as well Bright fullspectrum light Bipolar disorders manic and depressive episodes Bipolar The manic episodes are more severe and can include restlessness excitement rambling thought loss ofinhibitions Bipolar ll much milder manic phases hypomania which include agitation and anxiety Treatments for bipolar Lithium carbamazepine Depakote and Valproate all block the synthesis of arachidonic acid a precursor of cannabinoids in the brain which is produced when the brain is inflamed Lithium does not increase GABA activity but the other two do Since GABA is inhibitory we assume that these drugs reduce manic symptoms by inhibiting brain activity Valproate stimulates growth of axons and dendrites Schizophrenia Acute sudden onset good prospects of recovery quotEden Expressquot by Mark Vonnegut Chronic gradual onset longterm course harder to treat Two classes of symptoms of schizophrenia 1 Positive symptoms Psychotic cluster delusions hallucinations disorganized cluster inappropriate behavior emotional displays bizarre behavior thought disorder 2 Negative symptoms flat affect weak social interactions problems with speech and working memory ls schizophrenia genetic There is evidence for and against FOR greater concordance in dizygotic twins than in other siblings AGAINST The concordance rate for monozygotic twins is only 50 Neurodevelopmental hypothesis Brain abnormalities that occur in prenatal or neonatal development Evidence for this hypothesis 1 A number ofdifferent neonatal complications have been linked to schizophrenia 2 Schizophrenics show certain brain abnormalities a decreased volume in the left temporar and frontal cortex b larger ventricles c smaller cell bodies especially in the neurons of the hippocampus and right prefrontal conex d unlike most people who have a larger planum temporale in the left hemisphere schizophrenics have a larger right pt e lower than normal left hemisphere activity 3 abnormalities in development have been shown to impair behavior in adulthood People born in winter have a slightly higher risk of schizophrenia Why Possibilities more complications in delivery in the wintertime in uenza and other viruses occur most often in the winter Treatment Antipsychotic drugs neuroleptics 1 Phenothiazines chlorpromazine Thorazine 2 Butyrophenones Haldol Block dopamine synapses Dopamine hypothesis Schizophrenics have higherthannormal dopamine activity Evidence in support ofthis hypothesis 1 Drugs that block dopamine receptors reduce schizophrenic symptoms 2 Repeated doses ofamphetamines or cocaine can produce similar symptoms stimulantinduced psychosis Glutamate hypothesis Schizophrenics have lowerthannormal glutamate activity Evidence in support ofthis hypothesis 1 Brain imaging data have shown that schizophrenics have lowerthannormal glutamate levels in their brain especially in the prefronal cortex and hippocampus 2 PCP which inhibits glutamate receptors produces symptoms similar to schizophrenia including hallucinations thought disorder and memory loss REVIEW Ill3f genetics there is greater concordance in monozygotic vs dizygotic twins and greater concordance in blood siblings than in adopted siblings hormones there is no correlation between levels of sex hormones in adults and sexual orientation but there is evidence that males who are exposed to less testosterone levels early in life show more interest in other males and that females exposed to higher levels oftestosterone show interest in other females prenatal environment mothers of homosexual sons recalled higher than average levels of stressful experiences during pregnancy homosexual men tend to have older brothers brain anatomy homosexual men have a larger anterior commissure than heterosexual men which is closer in size to that of a woman the SCN is larger for homosexual vs heterosexual men and a part ofthe hypothalamus the dimorphic nucleus is smaller in homosexual men closer in size to that ofa woman Ill13a Kanzi amp Malika understand more than they can produce use symbols to name and describe objects even when those objects are not present request items they cannot see can describe past events can make original requests U39PFDNT Using language in a creative manner and describing events not just in the present Ill2f The rst mechanism is hormonal before experience between the mother and infant can create a bond Oxytocin is one such hormone that kicks in during the rst few days of life Afterthat the hormonal effect dissipates and bonding becomes experience dependent III9f In the alarm phase of stress response cortisol gets produced Small to moderate amounts of it actually stimulate memory activating the amygdala and hippocampus This enhances memory consolidation and storage But prolonged stress damages the hippocampus and impairs memory Ill9d 1 hippocampus size as people age their hippocampus shrinks but hippocampus size does not predict memory loss 2 rate of shrinkage this is correlated with memory performance higher rate of shrinkage results in greater memory impairment 3 less than average activity less in the hippocampus is related to memory performance supported by data 1 12007 The visual system is wired such that the information from the right visual field in both eyes goes to the right hemisphere and left visual field to the left hemisphere Splitbrain patient Generally these were patients who had severe epileptic seizures that crossed the midline ofthe brain and so the corpus callosum was severed in these patients along with the anterior commissure to try and prevent the most seizures from crossing over In split brain patients the two hands sometime operate independently some complex tasks that involved both hands or perhaps visual and auditory processing simultaneously could cause problems but in general these patients are highfunctioning and it39s hard to know in most situations that they have a de cit When information is presented to the left hemisphere which is the area where language processing happens they can name objects they see but they dif culty drawing them Objects to the right hemisphere show the opposite pattern Left hemisphere is dominant for speech in more than 95 of right handers and in 80 of left handers it is also better at language comprehension although the right hemisphere has SOME language comprehension The right hemisphere is better at visuopatial processing and that includes drawing information The left hemisphere is more likely to process detailed information about visual stimuli and the right hemisphere overall patterns The left hemisphere has a larger planum temporale which is a structure found in the temporal lobes and associated with language process It39s larger in the left hemisphere for 65 of people Young children resemble splitbrain patients in some ways because the commissures in their brains are not fully developed yet For example and infant with one arm restrained will not reach across hisher body to grab an object If you give toddlers two fabrics one placed in each hand and ask them to determine whether the fabrics are the same or different they will have a hard time with the task showing high error rates Some people are born without a corpus collosum and they do much better than split brain patients in a number of tasks involving auditory and visual processing the use of both hands simultaneously or language processing by the right hemisphere The two hemispheres are less specialized so that more language processing occurs in the right hemisphere and more visualspatial processing in the left Moreover these individuals still have an intact anterior commissure and a hippocampal commissure which allows the two hemispheres to communicate to some degree In right handers left hemisphere is dominant for speech In lefties you can have left hemisphere dominance righthemisphere dominance or a mixture ofleft and right Language Processing in animals and children KanziMalika are a type of bonobo called a bonobo They use language in creative ways they refer to events in their past and to objects that are not in their eld ofvision and they refer to objects not just when they want or need them Why are they so much more advanced in language production than other animals that have been taught languages 1 Bonobos may have more language ability than chimps 2 KanziMalika started young 3 They may have learned from observing their mother Alex the grey parrot Give give spoken answers to spoken questions involving color number shape and other characteristics ofobjects Children In the first five years they go from a vocabulary ofzero to several thousand words but perhaps more significantly they learn to use the grammatical rules oftheir language The study of language acquisition had been dominated by behaviorists who claimed that language wasjust a learned behavior until Noam Chomsky introduced his ideas about nativism which are based on the premise that children are born with a language acquisition device In other words language acquisition is hardwired so that children have an innate understanding ofgrammar syntax and other languagerelated rules There is also the idea ofa critical period in language acquisition language is most easily acquired prior to a certain age This point is somewhat controversial because there is evidence for and against a critical period For Children are much more likely than adults to learn a second language Against No sharp cutoff in terms of learning a second language Twoyearolds are better than 4 yo39s who are better than 6 yo39s Language De cits Broca39s and Wernicke39s aphasia Broca39s aphasia affects language production whereas Wernicke39s affects language comprehension The story is more complicated ln Broca39s aphasia the patient has trouble with pronouns prepositions conjunctions and articles Patients with Wernicke39s aphasia show anomia or the inability to utter or remember certain kinds of words mostly nouns and verbs Dyslexia people who are born dyslexic have certain anomalies in brain structure 1 Their planum temporale is more likely to be bilaterally symmetrical as opposed to being larger on the left side 2 In some cases they have more development of languagerelated centers in the right hemisphere compared to the left hemisphere 3 Fewer connections of lnanguagerelated brain areas Theories that account for dyslexia 1 Impairment in visual processing This theory is not wellsupported 2 Impairment in auditory processing There is evidence of lessthannormal response to certain speech sounds 3 Problems connecting visual and auditory information 4 Differences in attention Dyslexics don39t shift their attention from one target to the next in the same way that quotnormalquot individuals do and when they focus their visual attention directly on a word they are more likelty to process a word or letter that is 510 degrees to the right of their focal point ATTENTION Does the brain exert more effort to attend to a salient ie relevant stimulus or to tune out a distractor stimulus Research has shown that the brain is more active when attending to a salient stimulus compared to a nonsalient stimulus but that brain areas are not necessarily more active in tuning out some types of irrelevant stimuli over others See example in Fig 1418 on p 443 Deficits in attention Spatial neglect Tendency to ignore the left side ofvisual space and of the body directing attention to the right If a patient with neglect is asked to cross out all of the H39s that make up a larger letter they will only cross out the ones on the right However if asked they will correctly identify the letter as an E suggesting that their de cit is NOT one ofvisual processing How to deal with these de cits 1 You can teach patients with neglect to look left but the bene t will be shortterm 2 You can have them cross their arms and that tends to improve their awareness of their left side and speci cally oftheir left arm 3 You can have them turn to the left when looking or hearing something on their left side Attention de cit hyperactivity disorder ADHD is a disorder that is characterized by hyperactivity impulsiveness temper flairs difficulty being organized and problems both inhibiting and disinhibiting attention People with ADHD show speci c patterns of performance on certain tasks 1 Choice delay task Do you want the smaller reward now or the bigger one later The vast majority of people ADHD go for immediate gratification 2 Stop signal task You see a signal and are asked to press a button unless you get the quotstopquot signal quotDon39t press the buttonquot People with ADHD are less likely to be able to stop the button press in response to the stop signal 3 Attentional blink You see a string of letters and you have to respond to a letter that is a different color than the rest Then you have to report whether or not a particular letter such as an R appeared after that colored letter quotNormalquot people tend to miss the R if it appears 100700 ms after the colored letter For people with ADHD this quotattentional blinkquot lasts much longerwe over a second Brain Differences People with ADHD have 1 Smaller brain volume 95 of normal 2 Smaller right prefrontal cortex 3 Smaller cerebellum The main drug treatment for ADHD has been the use of stimulants such as Ritalin methylphenidate and Aderrall amphetamine 111307 Learning amp Memory Classical conditioning Pair a conditioned stimulus CS with an unconditioned stimulus UCS to produce a conditioned response CR Operant conditioning A reinforcer changes the probability of a certain behavior Is there a speci c brain area or brain change associated with learning Karl Lashley Search forthe quotengramquot which is the physical representation oflearning Lashley39s research generated two principles 1 Equipotentiality All parts of the cortex are equally involved in learning and any part could substitute for another 2 Mass action The cortex works as a whole and the more cortex is involved in a task the better Two faulty assumptions 1 The cortex is the best or only brain area to study if we understand learning 2 All kinds of memory and learning are the same physiologically Possible sites of engram 1 The cerebellum has a structure called the lateral interpositus nucleus LIP in classical conditioning cells in the UP show greater activation for the conditioned stimulus once conditioning has happened 1 Hippocampus size There is not a good correlation between hippocampus size and memory loss in older adults but there is a correlation between the extent of memory loss and the rate of shrinkage ofthe hippocampus 2 Hippocampus activity Evidence of increased activity in the hippocampus during memory tasks and there is an especially strong correlation between verbal memory and hippocampus activity What kind of memory is associated with the hippocampus 1 Declarative memory especially episodic memory Damage to the hippocampus tends to impair performance on certain kinds of memory tasks such as delayed matchingtosample tasks Example quotConcentrationquot game show 2 Spatial memory Rats with damage to their hippocampus have problems on a radial maze task in which they have to locate the arm of maze that has a food reward at the end of it Impaired rats will keep going down the arms where they already found food suggesting that they don39t remember where they39ve been They also struggle with the Morris maze task in which they have to navigate through water to locate a platform 3 Configural learning Learning that speci c stimuli eg shaped objects are associated with speci c outcomes Example you get a reward if you choose the circle over the square Types of memory damage 1 Korsakoffs syndrome Caused by brain damage due to thiamine a type of B1 vitamin de ciency for very long periods oftime usually related to alcoholism Severe alcoholics will use alcohol as their primary energy source and will suffer nutritional de ciencies as a consequence Symptoms of Korsakoffs retrograde and anterograde amnesia confusion apathy and extensive confabulation make up stuff usually about the events in their lives 2 Alzheimer39s Better procedural than declarative memory and they show de cits in both implicit and explicit memory Progressive leading gradually to more sever memory loss and confusion as well as delusions restlessness sleeplessness loss of appetite hallucinations ls Alzheimer39s disease genetic Evidence for Link between Alzheimer39s disease and chromosome 21 People with Down39s syndrome almost always get Alzheimer39s if they live long enough and a speci c gene on chromosome 21 has been linked to earlyonset Alzheimer39s Evidence against Half ofall Alzheimer39s patients have no family history ie no known relatives with the disease Environmental factors such as diet have been linked to some extent to Alzheimer39s Smoking and drinking coffee reduce your likelihood of having the disease Mechanism of Alzheimer39s onset involves the metabolism ofamyloid proteins in the brain A normal amyloid protein has 40 amino acids and in Alzheimer39s a form ofthe protein is produced that has 42 amino acids These proteins produce a type of deposit called plaques that are the result of the degeneration of axons and dendrites A separate protein called a tau protein produces tangles which are the result of damage to cell bodies Current methods of treatment 1 Drugs that stimulate acetylcholine receptors or that prolong acetylcholine release delay the onset of memory de cits 2 Drugs that stimulate cannabinoid receptors can slow the progression ofthe disease 3 Drugs that block amyloid production antioxidants 4 lmmunization Introduce amyloid 42 into young people39s bodies they will produce antibodies to destroy it because it39s seen as a foreign protein 11607 CH11 Reproductive Behavior Menstrual Cycle 1 After the end of a menstrual cycle the anterior pituitary releases folliclestimulating hormone FSH which promotes the growth and release ofa follicle in the ovary The follicle contains the egg as well as nutrients and hormone systems It produces estradiol form of estrogen 2 Toward the middle of the cycle the follicle produces more FSH receptors which trigger more hormone release which causes an increase in the release of estradiol 3 The increased release of estradiol causes an increase in the release ofluteinizing hormone LH from the anterior pituitary which triggers the release of the egg from the follicle 4 The remnant of the follicle releases progesterone which prepares the uterus for implantation of the fertilized egg and which inhibits the release of more LH 5 Toward the end ofthe cycle levels of LH FSH estradiol and progesterone all decline lfthe egg is not fertilized the lining of the uterus is cast off and the cycle begins again Towards the end of pregnancy the female secretes large amounts of estradiol prolactin and oxytocin Prolactin is necessary for milk production but all three are important for stimulating maternal behavior Men have vasopressin which helps with bonding with both one39s mate and offspring Emotion What is it It is some combination of cognition behavior and feeling state Behavior includes psychophysiology JamesLange Autonomic arousal and skeletal muscle movements come first the interpretation follows According to William James we experience fear when we observe ourselves running from the bear Facial efference Output of facial muscles affects our mood Schachter amp Singer The body cannot differentiate arousal based on any two emotions Only by interpreting situational cues do we define and label that undifferentiated arousal as a speci c emotion ls arousal necessary for emotion No Patients with pure autonomic failure who have no changes in heart rate bp perspiration during psychological stress still report the same emotions as anyone else ls arousal sufficient for emotion No You can autonomic arousal without emotion For example let39s do jumping jacks Some folks claim that emotions evolved out of physiological responses The classic example is DISGUST Disgust activates the insula which is the primary taste area in the cortex and the olfactory bulb which processes smell In fact both of those areas are close to the amygdala which is one of the primary emotion centers in the brain Fear escape from danger Anger to defend oneself from an attacker Disgust to protect us from something toxic Prefrontal cortex speci cally the orbitofrontal cortex Related to emotional decision making in which we weigh risks and rewards Iowa Gambling Task The player chooses cards from 50 and 100 decks and the objective is to collect as much money as possible The decks have occasional penalties associated with speci c cards It turns out that the 100 decks have greater penalties and result in overall losses whereas the 50 decks result in overall gains Patients with damage to the CFO cannot delay shortterm grati cation long enough to receive the longterm gains and so they keep playing the 100 decks Aggressive Behavior Is it genetic or environmental There is evidence for both Genetic Monozygotic twins resemble each other much more in terms of violent behavior than do dizygotic twins or nontwins Those resemblences are more likely to be true in childhood and adolescence however Also adopted children more closely resemble their biological vs their adoptive parents in terms of criminal record and other signs of aggression Environment The resemblence between twins goes down with age Also prenatal environmental plays a role in aggressive behavior Women who smoke during pregnancy are more likely to have male offspring who engage in violent behavior In the genetic corner is testosterone levels Testosterone levels are significantly higher in men imprisoned for violent crimes compared to control subjects but these effects are small Serotonin turnover the rate with which serotonin is released and resynthesized in the brain There is evidence that low turnover is correlated with aggressive behavior 1 Suicide rates are highest in the spring when serotonin turnover is lowest 2 Serotonin levels in the brain predict a number ofviolent behaviors including juvenile delinquency suicide attempts and convictions for violent crimes 3 People fed diets low in tryptophan show a tendency to aggressive behavior as do people who have low levels of tryptophan hydroxylase an enzyme that is important for the synthesis of serotonin from tryptophan Amygdala Enhances the startle response The amygdala gets input from pain fibers vision and hearing And its output goes to the hypothalamus which controls autonomic response It also has axons that project to the prefrontal cortex which controls approachavoidance behavior riskreward assessment KluverBucy syndrome The monkeys with amygdala damage become placid and tame They are not afraid of stimuli that would normally induce fear such as re and snakes and large animals They also don39t react normally to other monkeys39 threat gestures In humans facial expressions of other people are important emotional cues We recognize angry expressions faster ifthey are directed at us and fearful expressions faster if they are directed to our side The amygdala shows a greater response to fearful expressions directed towards us and to angry expressions directed toward our side Why Those stimuli are more ambiguous and require more ffort to process So the amygdala is trying to interpret emotional stimuli People with amygdala damage report normal emot5ions but have a hard time processing subtle emotional cues and they are more likely to pay attention to irrelevant cues in an emotioninducing situation than normal individuals Benzodiazepines including valium interact with the amygdala They bind to GABA recpetors in the amygdala hypothalamus midbrain and some cortical areas GABA is an inhibitory neurotransmitter By binding to the receptor BDZs cause GABA to bind more tightly to the receptors Because GABA is inhbitory the net effect is to turn off fearrelated responses STRESS Hans Selye general adaptation syndrome the body responds to stressors in three stages 1 alarm increases sympathetic arousal 2 resistance the body repairs damage created in teh alarm phase and the adrenals secrete corticosteroids such as cortisol which functions to increase blood sugar levels 3 exhaustion the nervous system and immune system no longer have the energy to function properly HPA axis hypothalamus pituitary and adrenal 1 hypothalamus releases corticotrophin releasing factor CRF 2 this triggers the anterior pituitary to release ACTH adrenocorticotropic hormone 3 this triggers the adrenals to release cortisol The adrenals also secrete epinephrine and norepinephrine which stimulate sympathetic arousal The effects of stress on the immune system are as follows 1 During the resitance phase there is an increase in immune activity 2 During the exhaustion phase energy gets directed towards glucose metabolism and away from protein synthesis including the synthesis of immunoproteins 103007 Sex hormones Organizing effects At a sensitivecritical period hormones determine whether or not the brain body will develop male or female characteristics Activating effects At speci c points in the life cycle when a hormone temporarily activates a certain response The default setting for humans is female Unless testosterone is released at a critical period the individual will have the secondary sexual characteristics of a female Sex and gender Sex is simply your genetic makeup XX or XY but gender is far more complex because it39s due to a combination of factors including cognition Gender has to do with how individuals perceive themselves Sexual variations Hermaphrodites a small percentage of newborns have a combination of male and female genitalia or genitals that are somewhere inbetween Pseudohermaphrodites are more common 1 in 2000 individuals There is enough ambiguity at birth to make a proper identi cation of sex difficult Androgen insensitive males Androgen refers to male hormones including testosterone Genetically male but has the secondary sexual characteristics of a female more or less Generally these individuals have broader shoulders and narrower hips than the prototypical female and no body hair whatsoever A tribe in the Dominican Republic that is fairly isolated geographically and so is susceptible to intermarriage A genetic anomaly has occurred in that population a group of individuals who are called quothuevodocesquot These people have a de ciency in an enzyme that converts testosterone to dihydrotestosterone which is what signals the production of secondary sexual characteristics At puberty other enzyme systems kick in When that happens these individuals go from being girls to men congenital adrenal hyperplasia CAH overdevelopment ofthe adrenal glands from birth This causes largerthannormal levels of testosterone in the body Genetically the individual is female but the effect is one of masculinizing the external genitals 102307 Announcements 1 Midterm2 next Tuesday CH10 lnternal Regulation Homeostasis Selfregulation There is a set point which is the point at which a variable needs to be held eg an ideal temperature and the body regulates the variable to hit that set point Thermostat When the temperature drops below the set point the heat turns on and when it goes above it the AC turns on Body Temperature Animals39 body temp is determined by certain factors a ambient temperature b physiological mechanismssweating panting licking shivering decreasing blood flow to the skin surface and extremities fluf ng fur behavioral mechanisms nding a warm or cool place clothing activity huddlingcuddling Why 370 986 Much above that temperature the proteins in our bodies denature Much below that temperature muscle bers don39t operate at their peak Brain areas associated with temperature regulation are the preoptic area and anterior hypothalamus POAHA Fever Why do we get a fever Bene ts It keeps bacteria from growing at the higher temperatures because the bacterial proteins denature Risk A fever above 390 can be harmful and above 41 can be deadly Thirst Vasopressin secreted by the posterior pituitary and raised bp by constricting blood vessels this conserves water and increases pressure for a given blood volume It is also known as antidiuretic hormone ADH because it allows the kidneys to reabsorb water from urine which in turn makes the urine more concentrated Two kinds ofthirst 1 Osmotic thirst this comes from eating salty foods which causes sodium ions to build up in the blood and the extracellular fluid The sodium buildup causes waterto move from the inside of the cell to the extracellular fluid Neurons in two brain structures called the OLT subfornical orgal which line the third ventrical detect water loss and signal to the hypothalamus that there is a need for more hydration 2 Hypovolemic quotlow volumequot thirst this comes from a loss of uids which can occur through sweating bleeding vomiting diarrhea There are two mechanisms in the body for detecting loss of blood volume 1 Receptors in the veins signal the kidneys to release renin which is a precursor to angiotensin II this hormone is similarto vasopressin in function among other things it constricts blood vessels and increases blood ow 2 Subfornical organ detects lower blood volume Sodiumspeci c thirst When you have osmotic thirst you can quench that thirst by drinking pure water but when you have hypovolemic thirst you need to add electrolytes Sodiumspeci c thirst occurs when you dilute sodium and other ions in your blood stream When sodium reserves are low the adrenal glands secrete aldosterone which causes the kidneys salivary glands and sweat glands to retain salt HUNGER The factors that determine food selection 1 Types ofenzymes available in the digestive system Lactasean enzyme that helps in the digestion of lactose in dairy products 2 lmitation learn from those around us 3 Taste We tend to select sweet foods avoid bitter foods and eat salty and sour foods in moderation 4 Learning We learn to reinforcement the consequences of eating certain foods The factors that affect hunger 1 Oral factorsif we don39t taste chew and swallow our food we tend to nd it unsatisfying 2 Stomachintestines distension of the stomach sends messages to the brain about the stretching ofthe stomach vagus nerve and about the contents of the stomach splanchnic nerve Between the stomach and small intestine is the duodenum which releases the hormone CCK This hormone acts to limit meal size by closing the sphincter between the stomach and duodenum CCK also signals fullness to the hypothalamus 3 Blood glucose levels triggerthe secretion of insulin by the pancreas lnsulin allows glucose to enter the cells lnsulin levels increase after a meal and this increase tends to sginal fullness Brain areas associated with hunger Lateral hpothalamus controls insulin secretion and facilitates feeding behavior An animal with damage to that area refuses food and water VMH Damage to this area leads to overating and weight gain because the individual or animal will eat normalsized meals but more frequently VMH has something with fullness but regulates the frequency rather than the size of the meal PVN Inhibits the lateral hypothalamus and thus limits eating and drinking Damage to this area result in much largerthan normal meals Arcuate nucleus there are two sets of neurons in this nucleus one signals fullness and the other signals hunger The output ofthis structure connects to the PVN Genetic evidence for obesity Twin and adoption studies REVIEW SESSION ll7e lndicate which cortical structures process auditory information Primary auditory cortex superior temporal lobes Secondary auditory cortex surrounds the primary auditory cortex ll7d Explain the volley principle No single auditory receptor can re at a rate compatible with the highest frequency sounds So instead ofone receptor ring 1000 times you could have 10000 receptors firing at one time and the effect would be the same A volley is a synchronized ring of receptors or cannons ll9f Explain why there seems to be so much specialization among olfactory receptors There are thousands of smells and unlike tastes which reduce to combinations of ve basic avors there are no known basic or fundamental smells that serve as the quotbuilding blocksquot for other smells ll9c Explain how you would prove the existence of the ve kinds of taste receptors Crossadaptation lfyou puts drops ofa certain flavor like sweet on the right receptors eventually you get adaptation which means that the receptors become fatigued But then if you introduce a different avor the receptors will be able to taste it quotfreshquot indicating that there is NO crossadaptation ll9j Compare the VNO of adult humans with that of other mammals The vomeronasal organ VNO is associated with the detection of pheromones In humans it is relatively small compared to other mammals 18d Discuss the role of leptin in regulating eating behavior mild prosopagnosia and may have problems with subtle visual discrimination tasks Cataracts in left eye Moderate prosopagnosia after cataract surgery Hunger 101607 CH9 Wakefulness amp Sleep Biological Clock Circadian rhythms daily patterns of sleep and wakefulness Circannual rhythms yearly patterns such as those migratory animals Suprachiasmatic nucleus SCN in hypothalamus Neurons in the SCN re at specific times of day this area controls activity in the pineal gland which release the hormone melatonin that increases sleepiness The freerunning rhythm ofthe SCN is more than 24 hours There are cues called quotzeitgebersquot timegiver are used by the SCN to set its rhythms One zeitgeber is light others are temperature meals exercise Disruptions of the biological clock 1 jet lag Disruption ofthe circadian rhythm due to changing time zones it39s harder going EAST than WEST because you have to go to bed earlier than you39re used to 2 Shift work When you39re sleeping in the morning or afternoon when your body temperature and metabolism are peaking you will not sleep soundly or for more than a brief duration Stages of Sleep NREM stages Stage 1 Body relaxes muscle tone diminishes heart rate slows breathing becomes deeper brain wave activity becomes slower more irregular increase alpha activity compared to waking beta 1430Hz alpha 813 Hz theta 47 Hz delta 054 Hz Stage 2 Brain wave activity that is characterized by sleep spindles which are bursts of relatively fast 1214 Hz activity and K complexes which are bursts of highamplitude activity Stage 3 An increase in slow wave activity ie theta and delta with 20 delta Stage 4 Primarily theta and delta activity defined by having at least 50 delta activity REM Sleep Paradoxical sleep REM seems like deep sleep in some ways and very light sleep in other ways lncreased activity Brainwave activity is relatively high closest ofany sleep stage to waking increase in eye moevements increases in heart rate bp and respiration rate although irregular increased genital arousal Decreased activity Nearly complete loss of muscle tone the skeletal muscles become relaxed to the point of paralysis 8090 of REM awakenings produce a dream report These dreams are characterized by a PLOT narrative storyline and mental imagery usually visual REM sleep deprivation Mental fatigue REM rebound When you39re allowed to have REM sleep you have more than the normal amount to compensate for what you lost Brain areas associated with sleep and wakefulness 1 The SCN in the hypothalamus 2 Reticular formation axons from this area extend into the hypothalamus thalamus and basal forebrain regulates arousal levels 3 Locus coeruleus found in the pons it39s inactive most ofthe time but has bursts of activity that increase wakefulness and that strengthen the storage of recent memories The LC is silent during sleep 4 Basal forebrain This area is located just in front of and above the hypothalamus axons from the BF extend into the thalamus and cortex it releases acetylcholine which is an excitatory neurotransmitter and that thends to increas arousal but it also releases GABA which is inhibitory and essential for sleep Parts ofthe BF stimulate sleepiness and other parts stimulate arousal Adenosine amino acid inhibits the BF cells responsible for arousal caffeine blocks adenosine receptors Physiology of REM Sleep PGO Wave PonsgtLateral Geniculate NucleusgtOccipital Cortex Every eye movement in REM is accompanied by a PGO spike Activity in the pons triggers the onset of REM sleep Sleep Disorders lnsomnia Sleep onset and sleep maintenance Sleep apnea Inability to breathe during sleep often associated with individuals who are obese Narcolepsy Considered a quotparasomniaquot which is a condition in which sleeping intrudes on waking life There are four characteristics of narcolepsy 1 Gradual or sudden attacks of sleepiness during the day 2 Occasional cataplexy Muscle weakness while awake 3 Sleep paralysis The inability to move while falling asleep or waking up 4 Hypnogogic hallucinations Dreamlike experiences that cannot be distinguished from waking reality Periodic limb disorder Involuntary muscle movements during NREM most common in older adults who have possibly had a microstroke or other brain trauma REM behavior disorder Movement during REM Night terrors Waking up from NREM with intense anxiety most common in children NREM quotsleep mentationquot is different from dreams when people are awakened from Stage 3 or 4 sleep they report vague abstract experiences but nothing that resembles a REM dream in terms of plot or imagery Why do we sleep 1 Conserve energy Why can39t we conserve energy by just lying still for several hours Why do we have to undergo the changes in consciousness associated with sleep 2 Restorative function Sleep increases the repair and synthesis of proteins in the brain synapses get reorganized during sleep 3 Strengthening of memories When people learn information during the day certain brain areas are activated and those same areas get reactivated that night during sleep The extent to which the individual learns the information is directly correlated with the amount of activation during sleep None of these theories accounts for REM sleep Why do we have to undergo this strange paradoxical stage of sleep 1 Maurice 1998 REM shakes the eyeballs so that the corneas can get the oxygen they need 2 Activationsynthesis Hobson amp McCarIey Random activation in the pons and other brain areas and the mind tries to make sense of that activation For example activation ofthe vestibular system which provides information about orientation in 3D may give the impression of ying Firing of the motor cortex might result in a chase dream One criticism is that this theory has put too much emphasis on the pons and there is evidence of dreaming in people who have quotpontinequot damage There is no established correlation between activity in speci c areas and the content of dreams Lucid dreaming research indicates that dreams are not solely the result of random brain activity 3 Clinicoanatomical theory Dreaming is thinking that occurs in the absence of information from the sensory organs or from the primary motor cortex 10907 Prosopagnosia Damage to the boundary between the occipital and temporal cortex quotCognitive Neuropsychologyquot by Elizabeth Warrington CH8 Movement Three types of muscles Striated skeletal muscles that control movement ofthe body relative to the environment Smooth muscles of the internal organs Cardiac muscles of the heart usually considered smooth muscle ber but have certain properties in common with striated muscle Striated muscles are antagonistic Paired muscles that move a part of the body in opposing directions exors vs extensors adductors vs abductors Proprioceptors Receptors that detect the position or movement of a body part One kind of proprioceptor is a muscle spindle which attached to a muscle and when the spindle is stretched it sends a message to a motor neuron which causes the muscle to contract A second distinction among muscles is fasttwitch vs slowtwitch Fasttwitch muscles produce fast contractions but fatigue easily they are need for intense strenuous activity of short duration anaerobic slowtwitch produce less vigorous contractions without fatiguing easily There are three types of re exes that occur in newborns but not in adults Grasp re ex You put an object in an infant39s hand and it will grasp tightly Babinski You stroke the sole ofthe foot and the big toe will extend while the other toes fan out Rooting You touch the infant39s cheek and the head will tirn and the infant will begin sucking movements The parts ofthe brain associated with the control of movement Many cortical areas associated with movement are in the frontal lobes 1 The motor cortex This area does not have any direct connections ofthe muscles of the body its axons connect to the brainstem and spinal cord It is more important for comple movements talking writing hand gestures than for basic movements coughing sneezing gagging laughing 2 Premotor cortex This area is most active in preparation for a movement it receive information about the location of a target in space towards which a movement is directed 3 Supplementary motor cortex This area is responsible for planning and organizing a rapid sequence of events such as pushing pulling orturning an object 4 Prefrontal cortex This area responds to sensory stimuli noises lights that lead to a movement and calculate the probable outcomes of the movement 5 Posterior parietal cortex This area keeps track of the position ofthe body relative to space Figure 88 The cerebellum is involved in coordination and quotballistic movementsquot movements that are performed all at once in a quotsingle shotquot People with damage to the cerebellum have trouble with movements requiring accurate aim and timing tapping a rhythm clapping hands pointing at a moving object speaking writing typing or playing a musical instrument most athletic activities The ways to test for cerebellar damage include 1 Asking the subject to move hisher eyes from one xation point to another Normal healthy individuals do it in a single saccade with perhaps a small correction at the end Someone with cerebellar damage does it in a series of smaller saccades 2 Fingertonose test Normal healthy individuals do it in three steps a nger moves balistically to a point in front ofthe nose b finger remains steady at a point close to the nose for a fraction of a second c the nger moves to the nose in a slower movement that doesn39t depend on the cerebellum Someone with cerebellar damage either stops too soon or goes too far Motor pathways There are two main pathways coming offthe motor cortex 1 Dorsolateral tract This tract set of axon fibers controls contralateral movements in hands toes ngers 2 Ventromedial tract Controls movements involving both sides ofthe body such as neck shoulders trunk Consciousness and movement Do we consciously control our movements People report their decision to move a body part occurs 200 ms before the actual movement But the brain activity associated with the movement Le a readiness potential starts 500 ms before the movement Basal Ganglia in movement Globus pallidus releases GABA which is an inhibitory neurotransmitter and thus inhibits movment Input from the putamen and also the caudate nucleus essentially tells the globus pallidus which movments to inhibit Damage to the globus pallidus results in involuntary jerky movements See Fig 817 Parkinson39s Causes Early onset before age 50 is believed to be genetic late onset after 50 also be due to environmental factors exposure to herbicides pesticides The mechanism of Parkinson39s involves damage to the substantia nigra Lifestyle note People who smoke cigarettes or drink coffee are less likely to develop Parkinson39s Symptoms rigidity muscle tremors slow movements and dif culty initiating physical and mental activity Treatment Ldopa which is a precursor of dopamine that can cross the bloodbrain barrier Stimulation ofthe substantia nigra and the globus pallidus has resulted in at least temporation cessation of symptoms Antioxidants are used to slow down the destruction of dopaminergic neurons Neurotrophins are used to decrease the rate of apoptosis Huntington39s disease Damage to caudate nucleus putamen globus pallidus and cerebral cortex Symptoms arm jerks facial twitches tremors writhing depression memory impairment anxiety hallucinations delusions alcoholism and drug abuse sexual disorders Cause Genetic an autosomal not on a sex chrosome dominant gene Onset ofthe disease occurs between the ages of 30 and 50 Presymptomatic test Looks for the gene on Chromosome 4 This gene produces a mutant form ofa protein called Huntingtin that prevents the release of neurotrophins and also interferes with mitochondria in neurons lfthe globus pallidus which inhibits certain movements is damaged the result is uncontrolled and possibly violent movement There is no treatment for Huntington39s 10207 Announcements 1 Exam scores are posted online 2 To contact the grader respectfully katrinaemailarizonaedu 3 Answer Keys are posted in the glass case in the thirdfloor hallway of the Psyc Bldg 4 Grade Cutoffs are as follow A 2530 B 2024 C 1519 D 1014 5 Gandhi39s Birthday THE VISUAL SYSTEM Part 2 Types of cells in the visual cortex 1 Simple cells Feature detectors that detect edges and contours 2 Complex cells Detect changes in orientation 3 Hypercomplex cells Detect movement within the visual field primarily located in V1 Bottomup processing The sensory apparatus eg eyes provide the information from which your perceptual representations are formed Topdown Your quotsetquot which includes your expectations will dtetermine what you see There are visual pathways leading from areas V1 and V2 in the occipital cortex 1 Ventral stream downward visual pathway leads to areas in the temporal cortex that are specialized for indentifying and recognizing objects including detecting color brightness and shape 2 Dorsal stream up or back visual pathway leading to the parietal cortex and to two areas in the temporal cortex Medial Temporal CortexMTand Medial Superior Temporal Cortex MST this pathway provides information about movement including quotwherequot and quothowquot information quothowquot means that it lets the motor system find objects and determine how to grasp them Figure 619 shows the two pathways MT V5 Processes information related to the movement of an object within the visual field MST Processes information related to the movement of the field relative to the observer detects rotation or expansioncontraction of the visual field Disorders of visual processing Visual agnosia inability to recognize objects usually linked to damage in the occipital lobes Prosopagnosia inability to recognize faces usually linked to damage in the temporal lobes Developmental issues Critical or sensitive period in development If visual information is impaired in some way during this period it can have lasting effects on the individual Suppose that you close off an eye in a kitten The cortex becomes unresponsive to information from that eye Suppose you close off both eyes For the first few weeks the cortex remains responsive to both eyes but then it begins to have trouble with acuity orientation thalamus and to the primary auditory cortex A1 which is in the superior temporal cortex and also to the secondary auditory cortex which surrounds A1 There are two types of deafness 1 Conductive deafness Due to damage of the middle ear and the inability of the middle ear to transmit sound waves to the cochlea 2 Nerve deafness Damage to the cochlea to the hair cells specifically or to the auditory nerve Sound localization We use both ears to determine where a sound is coming from and we do so based on three types of cues a Differences in intensity between the two ears b Differences in the time arrival of sound to the two ears c Phase differences between the two ears The sound reaches the ears at two different points in its compression cycle TOUCH Three types of touch receptors 1 Simple bare neuron endings tend to be pain receptors 2 An elaborated ending Ruffini endings and Meissner39s corpuscles Ruffini are specialized to detect heat whereas the Meissner39s corpuscles detect light touch 3 Pacinian corpuscles Bare ending surrounded by nonneuronal cells that modify its function Detect largescale joint movements These receptors cover the skin surface of the body and connect to the central nervous system at various points in the spinal cord How does pain work Pain receptors release Substance P which is a neurotransmitter that transmits pain signals in the body There are a number of ways to alleviate pain 1 Opiate drugs and endorphins specifically in the body bind to opiate receptors on neurons that release Substance P and in doing so inhibit that release 2 Gate theory Nonpain stimuli can minimize the intensity of pain signals because neurons in the spinal cord that receive pain signals also receive other types of touch signals This explains why massage can be effective in minimizing pain 3 Capsaicin found in peppers releases Substance P faster than neurons can resynthesize it leaving cells essentially quotdrainedquot so that they cannot transmit pain signals But high doses of capsaicin can damage pain receptors CHEMICAL SENSES Taste and Smell The chemical senses are unique because they have to respond to a wide range of stimuli Taste receptors die off every two weeks and olfactory receptors every month Theories about how these receptors work 1 Labeledline theory Each receptor corresponds to a limited range of stimuli and sends a direct line to the brain 2 Acrossfiber pattern Each receptor responds to a wide range of stimuli and contributes a piece of the whole puzzle in terms of the perception of each There are five kinds of taste receptors found primarily on the edge of tongue They detect sweet sour bitter salty and quotumamiquot glutamate taste MSG Saltiness These receptors detect sodium ions and permit those ions to cross the sodium channels leading to depolarization of the membrane and action potentials Sourness When acids bind to receptors they close off the potassium channels keeping potassium trapped in the neuron and depolarizing the membrane causing an action potential Sweetness bitterness and quotumamiquot receptors are all metabotropic They stimulate the production of a Gprotein in the neuron which produces a second messengerthat will eventually trigger an action potential Information from the front 23 of the tongue is carried to the brain along a nerve bundle called the chorda tympani a branch of the 7th cranial neve taste info from the back of the tongue and the throat is carried along branches of the 9th amp 10th cranial nerve Taste receptors project to a part of the medulla called the nucleus of the tractus solitarius NTS which then leads to the following areas Pons That39s a relay for cranial nerves Lateral hypothalamus Regulates appetite Amygdala Emotion Ventral posterior thalamus Relay for all senses except olfaction Somatosensory cortex Detects texture lnsula Primary taste area of the brain OLFACTION Olfactory information does not break down into categories like taste Olfactory receptors are highly specialized and there are many different types Signal moves from the nose to the olfactory bulb to olfactory areas of the cortex and then to areas controlling feeding hypothalamus and reproduction Vomeronasal organ VNOset of receptors located near the olfactory receptors but in a separate area of the nose In adult humans it is tiny and appears quotvestigialquot Yet there is evidence of pheromone detection in humans Two examples given in your book 1 Women who spend time together find that their menstrual cyles become more synchronized 2 Women who are in a steady sexual relationship tend to have more regular menstrual periods There are gender differences in smell detection Women detect odors more readily and their brains respond more strongly to odors they also pay more attention to smells and care more about the smell of a potential partner Olfactory receptors are exposed to many toxins and pollutants that is why they only survive a month 92507 The Visual System The Eye light electromagnetic energy enters through the pupil which is an opening in the iris It is focused by the cornea and the lens and then is projected onto the retina which has the following types of cells Receptor cellstransduce light into an electrochemical signal Horizontal cellsinhibit other cells in the eye Bipolar cells intermediary cell that sends the signal to the ganglion cells Ganglion cells the cells that transmit the signal out of the eye through the optic nerve PPM The axons of the ganglion cells make up the optic nerve that carries electrochemical signals out of the eye and to the thalamus Two types of receptors 1 Rodsabundant in the peripheral area of the retina and respond to faint light but not as well to bright light 2 Cones abundant in the fovea which is the central part of the retina they are more useful in bright light and in color vision less useful in night vision How do receptors carry color information YoungHelmholtz trichromatic theory three kinds of cones in the eye each being sensitive to a specific part of the color spectrum short wavelength blue receptors medium wavelengthgreen and longred The ratio of activity among the three types of cones determines what colors we see Doesn39t account for afterimages Opponentprocess theory We perceive color in terms of three paired opposites redgreen yellowblue and whiteblack This explains why there are afterimages In the absence of activation of blue receptor we see yellow Neither theory accounts for color constancy which is when we can still identify a color correctly under different types of light Retinex theory quotretinexquot retina cortex This theory says the cortex compares information from various parts of the retina to determine brightness and color Color blindness Some people with color blindness lack one or two types of cones Some have all three but one kind is abnormal But the most common form of color blindness is one in which the red and green cones have the same photopigment The optic nerve Axons from ganglion cells in the retina The point at which the axons exit the eye produces a blind spot in the retina The optic nerve from the two eyes meet at a point called the optic chiasm Half of the axons from each eye cross over to the opposite side of the brain After crossing the optic chiasm these axons travel to the lateral geniculate nucleus LGN of the thalamus which in turns sends the axons to other pars of the thalamus and to the visual areas of the occipital cortex There are two main areas in the occipital cortex V1 and V2 From the occipital cortex the signal travels to other parts of the cortex including the inferior temporal cortex and the parietal cortex and some of the signal returns to the thalamus in a feedback loop Types of ganglion cells 1 Parvocellular neurons quotparvoquot means small small receptive field adapted to color and visual detail their axons travel primarily to the LGN 2 magnocellular neurons quotmagnoquot means large larger receptive field not color sensitive and connect to the LGN and to other nuclei in the thalamus 3 koniocellular neurons also have a small receptive field connected to the LGN other nuclei in the thalamus and the superior colliculus Before the signal leaves the eye information about edges and contours is refined This happens through a process called lateral inhibition The horizontal cells inhibit all the bipolar cells doubly except those at the edge of the activation area of receptors which only get inhibited on one side As a result the bipolar cells on the edge appear brighter So lateral inhibition serves to enhance the edges of what you39re seeing Area V1 in the occipital cortex is responsible for processing a great deal of information concerning shape and contour It is also important for the subjective experience of being aware of visual stimuli lfV1 is damaged we get cortical blindness which is called quotblindsightquot Blindsight patients can distinguish some visual features with betterthanchance accuracy How is it possible for someone with damage to V1 to distinguish visual stimuli There are two theories 1 Weiskrantz Even though V1 is damaged other brain areas associated with visual processing are still intact and they provide enough information to perform certain types of tasks 2 Gazzaniga quotIslandsquot of healthy tissue remain in an otherwise damaged V1 and even a few cells are enough to be able to do certain rudimentary visual processing tasks In the visual cortex there are three different types of cells that process visual information 1 Simple cells in V1 primary visual cortex their receptive fields are attuned to edges and rectangular areas 2 Complex cells found in V1 and V2 and they respond to angle or orientation 3 Endstopped hypercomplex cell detect movement of an object within the visual field 918 Announcements 1 Midterm 1 is next week We will cover CH6 first and then start the exam by 645pm Please make sure to be in class no laterthan 645 2 Review session todayAfter we cover CH5 3 CH6 is NOT on the first midterm Just CH 15 Brain Development and Plasticity Stem cells Undifferentiated cells that have the potential of developing into just about any kind of cell Development of neurons in five stages 1 Proliferation New cells are formed 2 Migration Neurons move to their eventual destination in the brain The migration of neurons and of axons within neurons happens through chemical attractants An axon will follow one attractant for a certain distance until it becomes insensitive to it and then it follows another attractant 3 Differentiation The neurons form axons and dendrites and then develop the specific structure and shape relevant to their eventual function 4 Myelination Glial cells help produce the myelin sheath that insulates the axon 5 Synaptogenesis Formation of dendritic branches and new synapses After prenatal development the only two kinds of neurons that have been observed to regenerate in mammals are olfactory receptors and hippocampal cells in rats but not YET in humans Although neurons may not regenerate they can form new dendritic branches Neural Darwinism The nervous system produces far larger numbers of neurons than it will keep as well as a larger number of synapses Through a selection process they get weeded out Some neurons are destroyed and others are kept apoptosis A selfdestruction program that is built into every neuron The default setting on that program is cell death The only thing that keeps neurons from selfdestructing at some point in development is the release of specific proteins called neurotrophins that promote the growth and maintenance of Both result in edema which is an accumulation of fluid The most effective ways of treating stroke are 1 Cooling the brain Slow down brain activity 2 Tissue plasminogen activator tPA breaks up blood clots in brain arteries 3 Cannabinoids Lowerthe amount of glutamate released in the brain glutamate inhibitors What happens after the brain is damaged by stroke or other means 1 Diaschesis Decreased activity in areas connected to the neurons that were killed by the stroke Area around the stroke that is called the penumbra Neurons in this area may not be killed but are damaged or affected in some way 2 Regrowth of axons This occurs primarily in the peripheral nervous system and at a rate of about 1 millimeter per day In the CNS axons regenerate 12 mm at most totally 3 Sprouting New branches form called collateral sprouts that attach to vacant synapses 4 Denervation supersensitivity The loss of certain neurons makes the remaining neurons of the same kind more sensitive to specific neurotransmiitters An interesting effect of amputation Reorganization of sensory information in the brain and also quotphantom limbquot REVIEW l1e Distinguish between Chalmers39 easy problem and hard problem Easy problem The observation and description of certain aspects of consciousness such as the relationship between sleep and waking There is an excellent understanding for instance of the relationhsip between the psychophysiology of sleep and the experiential aspects of sleep Hard problem Understanding how the brain gives rise to consciousness l2c Explain why it is difficult to distinguish between heredity and prenatal influences The genetics we share with our parents are going to dictate the kind of environment they create for us Obesity runs in families for at least two reasons One is shared genetics and the other is a shared environment that is the result at least in part of those genetic tendencies l5a Explain why an axon must regenerate an impulse instead ofjust conducting it Axons conduct impulses for long distances and so those signals would weaken as a result of resistance and other factors if it weren39t regenerated l5e Describe the molecular basis of the ACTION POTENTIAL 1 Voltage increases resulting in depolarization due to the flow of positive ions from adjacent areas 2 When the voltage crosses a threshold voltageactivated sodium channels open up 3 Sodicum rushes into the cell driven by both concentration and electrical gradients This raises the voltage to 30mV 4 Voltageactivated potassium channels open and potassium flows out drawn out of the cell by concentration gradients and no longer held back by an electrical gradient 5 Sodiumpotassium pump takes out the excess sodium and brings in potassium I4d Identify the cells of the brain that can and cannot divide Cannots neurons with two notable exceptions Cans glial cells l6b Explain how saltatory conduction works Action potentials are only generated at nodes spaces between sections of myelin sheath In the sections of the axon that are myelinated positive ions move rapidly along the inside of the membrane conducting the signal without regenerating the action potential l6c lndicate when impulses are transmitted without action potentials Local neurons have graded potentials in which the depolarization of the membranes is based on the intensity of the stimulus l9e Describe the relationship of D2 and D4 receptors with personality These are two different types of dopamine receptors One form of D2 receptors are more likely to develop in severe alcoholism D2 receptors are correlated specifically with alcoholism D4 receptors are correlated to quotnoveltyseekingquot personality types who are characterized by high impulsivity a short temper and exploratory behavior I15e Explain how gray and white matter relate to intelligence Does brain size correlate with intelligence Not very well but the amount of gray matter in the brain correlates to a greater extent I3b Name at least two plausible ways for altruistic genes to spread in a population 1 reciprocal altruism it39s adaptive for animals to help those who will help them in return 2 kin selection help relatives and therefore benefit your gene pool I10f Summarize the findings of Pert amp Snyder 1973 These researchers were the first to propose the existence of endorphin receptors l8c Describe the process by which neurotransmitters are released 1 The action potential reaches the end of the axon 2 At the axon terminal the depolarization causes calcium gates to open 3 The flooding of calcium into the axon terminal causes exocytosis in which the neurotransmitter is released from the axon terminal in bursts M b Discuss the four biological explanations of birdsong 1 physiological explantation the brain area that is linked to birdsong is larger in breeding males than in females and grows under the influence of testosterone 2 ontogenetic young males learn songs from adult males development of birdsong requires both the genes that prepare that male to learn to sing and the opportunity to hear the song at a sensitive period 3 evolutionary Birds that have similar songs have evolved from a single ancestor 4 functional The function of birdsong is to attract females and to warn away other males 91107 Caffeine Antagonist for adenosine lt binds to adenosine receptors without activating them Normally adenosine acts as an inhibitor for monoamines When adenosine receptors ar blocked the result is an increase in the activity of serotonin dopamine epinephrine and norepinephrine Alcohol Alcohol sensitizes glutamate receptors it binds to them in a way that causes them to respond more effectively to glutamate This is true in moderate doses and glutamate is an excitatory neurotransmitter So in moderate doses alcohol actually can stimulate receptors in the cortex hippocampus and nucleus accumbens But in larger doses alcohol overwhelms the glutamate receptors to the point that they become unresponsive At the same time alcohol in large doses will activate GABA recerptors GABA is an inhibitory neurotransmitter that inhibits among other things glucose metabolism CH4 Anatomy of the Nervous System Anatomical terms for direction Coronal crown separates front and back Sagittal side separates left and right Horizontal separates top and bottom Dorsal back Ventralfront Posterior back Anterior front Medial towards the middle lpsilateral On the same side Contralateral On the opposite side Components of the Nervous System See diagram The Brain l Hindbrain A Medulla Breathing heart rate salivation coughing vomiting sneezing It39s the point of connection for most of the cranial nerves 12 cranial nerves which monitor sensations and control muscle movements in the head B Pons This is the point wehre motor neurons cross over It contains the reticular formation reticulated having grooves The descending fibers of the reticular formation control motor areas of the spinal cord and the ascending fibers are associated with arousal and attention C Raphe system Associated with attention D Cerebellum Controls movement coordination timing sensory attention ll Midbrain A Tectum B Superior colliculusinferior colliculus Sensory information C Tegmentumsubstantia nigra Part of the brain39s dopamine system Dopaminergic neurons originate ONLY in these two areas ie these are the only places where cell bodies reside lll Forebrain A Limbic system 1 olfactory bulb sense of smell 2 hypothalamus basic drives hunger thirst sexuality sleep 3 hippocampus memory Lynn Nadel 4 amygdala emotions fear B Basal ganglia Caudate nucleus putamen globus pallidus nucleus accumbens Memory emotion movement attention rewardaddiction C Nucleus basalis Arousalwakefulness attention emotion D Thalamus Sensory relay E Cerebral cortex 4 lobes in each hemispheres Occipital cortex Back of head visual processing Parietal cortex Top of head touch somatosensory cortex sensory nerves from the body spatial information numerical information Temporal Cortex Sides of the head auditory information spoken language some visual information including face recognition memory emotion and motivation Frontal Cortex Front of head primary motor cortex planning problemsolving willpower attention Methods of studying neuroanatomy Types of brain scans 1 CT scans X ray slices of the brain 2 MRlnuclei of atoms in the brain react with magnetic fields high spatial resolution images 3 PET positron emission tomography injection of a radioisotope that produces gamma radiation functional imagery does not give good resolution of structures in the brain but it does allow the researcher to look at functional changes occurring over time 4 fMRl looks at changes in the magnetic properties of hemoglobin when it39s oxygenated and deoxygenated measuring changes in oxygen consumption offers good spatial and temporal resolution Research methods to study brain damage 1 Lesions Damage a specific brain area total removal ablation 2 Geneknockout Blocks a gene that produces certain neurotransmitters or receptors 3 Transcranial magnetic stimulation Can temporarily inactivate neurons in a region close to the magnetic stimulation Does size matter Brain size amp intelligence In humans there is only a low to moderate correlation between IQ and brain size 3 Across species braintobody ratios are predictive of intelligence 9407 The Synapse Research on Reflex Arcs Reflex automatic muscle response Reflex arc circuit that goes from the sensory neuron to the muscle via an interneuron and a motor neuron bypassing the brain Three characteristics of reflex arcs that suggested the existence of synapses A synapse is a specialized gap between neurons where electrochemical signals are transmitted 1 The rate of conduction of impulses in a reflex arc 15 ms is much slower than the rate of conduction along an axon 40 ms 2 lmpulses in a reflex arc do not follow the allornothing law but are cumulative a Temporal summation Two stimuli occuring close to each other in time produce a greater reflex response than either one by itself b Spatial summation Two stimuli occurring close to each other in space produce a greater reflex response than either one by itself 3 Reflex arc can excite certain muscles and inhibit other muscles Excitatory postsynaptic potential EPSP The electrochemical signal transmitted from one neuron presynaptic neuron across the synapse to a second neuron postsynaptic neuron produces a depolarization of the membrane of the second neuron just like an action potential In other words the signal causes more activation of the postsynaptic neuron compared to baseline Inhibitory postsynaptic potential IPSP The electrochemical signal causes a hyperpolarization of the postsynaptic neuron causing it to be less activated than it would at baseline All neurons have a spontaneous firing rate They are going to generate action potentials at a certain rate regardless of any stimulation from other neurons EPSPs cause the neuron to fire at a faster rate compared to that baseline and lPSPs cause the neuron to fire at a slower rate What happens at the synapse 1 The presynaptic neuron produces neurotransmitters Small molecules are produced in the axon terminal presynaptic terminal and larger molecules eg peptides are produced in the cell body 2 The neuron transports larger molecules to the axon terminal This transportation occurs in a spherelike storage quotcontainerquot called a vesicle 3 Action potentials travel along the axon until they reach the terminal There they trigger the release of the neurotransmitter into the synaptic cleft which is the gap between the presynaptic and postsynaptic neuron This release happens by a mechanism that involves calcium channels in the presynaptic terminals As the channels open and calcium binds to sites on the vesicle the reaction causes the membrane of the vesicle to open up so that the neurotransmitter is released 4 The neurotransmitter travels across the synapse and attaches to receptor sites on the postsynaptic neuron ln binding to the receptor the neurotransmitter can have an excitatory or inhbitory effect 5 After the neurotransmitter reacts with the receptor it gets released into the synapse 6 Once the neurotransmitter is released by the postsynaptic receptor it reenters the synaptic cleft where it can either be broken down by enzymes or recycled by the presynaptic neuron 7 The postsynaptic neuron may release some type of neurotransmitter that signals to the presynaptic neuron to slow down or stop the production of further neurotransmitter Types of neurotransmitters Amino acids buildings blocks of proteins they contain an amine NH2 and a carboxylic acid COOH examples include glutamate GABA Modified amino acids Acetylcholine the Hydrogens on the amine are replaced by methyl groups CH3 Monoamines Molecules that contain a single amine group a Catecholamines dopamine epinephrine norepinephrine b lndoleaminesserotonin Peptides Chains of amino acids endorphins substance P Purines Building blocks for DNA ATP adenosine Gases Nitric oxide NO How does a neurotransmitter exert its effect on the postsynaptic neuron 1 lonotropic effect The binding of the neurotransmitter to the receptor causes ion channels eg sodium chloride calcium to open in the membrane of the postsynaptic neuron Simple fast and shortlasting mechanism Excitatory ionotropic effects eg glutamate or inhibitory ionotropic effects eg GABA 2 Metabotropic effect The binding of the neurotransmitter to the receptor sets off a chain reaction that involves a quotsecond messengerquot which is another neurotransmitter that gets released by the postsynaptic neuron and that delivers the signal to other parts of the same neuron This is a slower longerlasting mechanism Hormones vs Neurotransmitters The same molecules can serve as both but hormones are more widely broadcast throughout the body whereas neurotransmitter tend to localized specifically within certain structures in the nervous system The hypothalamus and the pituitary gland are important and closely linked structures in the brain that play a central role in the production and release of hormones in the body The pituitary can be divided into two parts 1 The anterior pituitary secretes hormones that trigger the release of other hormones in the body ACTHactivates the adrenals TSH activates the thyroid FSH and LH activate the gonads gonadotropins GH growth hormone prolactine activates the mammary glands 2 The posterior pituitary gland is closely linked to the hypothalamus where two important hormones are produced oxytocin regulates sexual and parenting behaviors and vasopressin regulates water balance in the body The posterior pituitary delivers these hormones into the bloodstream Process 6 that takes place synapse is really two processes Inactivation of the neurotransmitter and Reuptake Inactivation is the breakdown of the neurotransmitter by enzymes Monoamine oxidase MAO breaks down monoamines such as dopamine and serotonin Reuptake involves transporter proteins in the presynaptic terminal that bind to the neurotransmitters and bring them back into the terminal Dopamine transporters DAT proteins that specifically bind to dopamine and are involved in the reuptake Drugs and the Synapse The body seeks homeostasis Anything that causes an imbalance in a neurotransmitter system results in some set of counterbalancing processes Stimulants Amphetamines cause increases in the release of dopamine whereas cocaine blocks the reuptake of dopamine by the presynaptic neuron Methylphenidate Ritalin acts in a manner similarto cocaine by blocking the reuptake of dopamine Why isn39t it more addictive The answer has to do with the method of ingestion Taking Ritalin in oral form produces a slow release of the drug into one39s system and the drug stays in the system longer Opiates Derivatives of poppy Opium heroin and methadone Of the three heroin is most addictive because of its speed of action Opiates bind to a receptor in the brain for endorphins endogenous morphine So opiates are mimicking a naturally occurring neurotransmitter and binding to a receptor site that is specific to that neurotransmitter ie endorphins Psychoactive drugs mimic some type of neurotransmitter in the body Cocaine mimics dopamine Psychedelic drugs LSD psilocybin mimic serotonin Opiates mimic endorphins Marijuana mimics endogenous cannabinoids such as anandamide The drug can act as an agonist that either causes an increase in production of the neurotransmitter or that mimics the neurotransmitter at either a receptor site or a transporter site or the drug can act as an antagonist interfering with a neurotransmitter Nicotine Acts on receptors in the nucleus accumbens that release dopamine They actually have receptor called quotnicotinic receptorsquot that are really acetylcholine receptors Acetylcholine is an excitatory neurotransmitter When acetylcholine or nicotine bind to the nicotinic receptors they excite the dopamine receptors in the brain causing more dopamine to be released in the nucleus accumbens Marijuana mimics endogenous cannabinoids and binds to cannabinoid receptors in the hippocampus cerebellum basal ganglia and cerebral cortex Hallucinogenic drugs like psilocybin and LSD mimic serotonin which is involved in mood regulation but also in perceptual processes Drugs have an affinity and efficacy Affinity has to do with how easily it binds to a receptor and efficacy has to do with how tightly it binds or how long it stays bound to the receptor 82807 Announcements 1 Lecture notes are posted online httpvaswebarizonaedu click on quotPsyc 302 Notesquot 2 Book release party Thurs Sept 20 430pm UA Bookstore Basic cell structures membrane separates the inside of the cell from its surroundings nucleus contains the chromosomes mitochondria metabolic activities ribosomes protein synthesis ribosomes tend to be found on the endoplasmic reticulum which is a set oftubes that transport proteins throughout the cell Basic neuronal structures Dendrites receive electrochemical signals Cell body contains the nucleus mitochondria ribosomes Axon neuron only has one sends electrochemical signals Parts of the axon 1 myelin sheath electrical insulation layer on the axons that improves the speed and efficiency of electrical conduction Lorenzo39s Oil 2 nodes of Ranvier nodes gaps in the myelin that exist to allow quotsaltatory conductionquot 3 presynaptic terminal the tip of the axon where chemical messengers called neurotransmitters are released into the synapse or gap between cells Glial cells Unlike neurons glial cells can regenerate They do the quotdirty workquot of the nervous system providing structural support removing waste and facilitating certain processes Types of glial cells 1 astrocytes involved in the reuptake and rerelease of neurotransmitters help recycle neurotransmitters also remove waste materials produced by dead neurons and they help control the amount of blood flow to certain brain areas 2 microglia remove waste materials viruses fungi and other microbes acting as a quasi immune system forthe brain 3 oligodendrocytes important in building the myelin sheath in the brain and spinal cord ie central nervous system 4 Schwann cells build myelin sheath in the peripheral nervous system 5 Radial glia type of astrocyte that guide the migration of neurons and the growth of their axons and dendrites during embryonic development Bloodbrain barrier The walls of capillaries in the brain that are made up of endothelial cells that arranged so tightly that they leave virtually no gap for chemical substances to get through This keeps toxins out of the brain Some substances need to get through How does that happen 1 Passive transport Small molecules like oxygen and carbon dioxide can get through the gaps in the bloodbrain barrier There are also specialized channels in the membrane that will draw in certain molecules such as certain vitamins like A and D that are fat soluble 2 Active transport Proteins in the membrane that expend energy to pump substances from the blood into the brain such as glucose amino acids other vitamins and hormones Types of neurons 1 motor sensory and interneurons motor neuronconnects to a muscle or gland if it connects to a muscle it controls muscle contraction sensory neuron part of a sense organ that receives some type of stimulation such as electromagnetic energy in the eye or mechanical vibration in the ear and converts it into a nerve impulse interneurons neurons that are only connected to other neurons they are contained within a specific structure such as the cortex of the brain 2 efferent vs afferent efferent carries a signal away from a structure afferent carries a signal to the structure NERVE IMPULSES Resting potential When the neuron is at rest it has a potential of 70 mV Forces involved in resting potential conduction The potential zips along the stretches that are insulated by myelin until the positive ions reach the next node where there are sodium channels that can open Local neurons that have very short axons don39t need to generate an action potential instead they have what is called a graded potential Action potentials operate by the allornothing principle You need a strong enough depolarization to open the sodium channels Otherwise nothing happens 82107 CH1 Major Issues in Biopsychology l Causal Relationships Explaining why certain behaviors happen from a biopsychological standpoint There are at least four types of explanations in biopsychology 1 Physiological Relates a behavior to activity in the brain or other organs Music perception example Physiological approach would look at the brain areas that are associated with music perception 2 Ontogenetic Describes the development of a structure or behavior Music perception example Music perception first appears at ages 46 months 3 Evolutionary perspective Reconstructs the evolutionary history of a structure or function Music perception example Comparative study of music perception in primates and humans 4 Functional explanation Answering the question of why a structure or behavior evolved as it did Music perception example Why does music perception exist What adaptive benefits are there in being able to perceive and appreciate and play music ll MindBody Problem Biopsychologists have to decide how they view the relationship between physiological and psychological processes Three philosophical positions a Materialism Everything that exists is ultimately material or physical in nature Even if psychological processes have an independent existence as a unique entity they are hypothesized to be caused by physiological processes Monism There is only one kind of quotstuffquot in the universe In the West most monists are materialists b Mentalism Everything that exists is ultimately mental Even physical events that surround us are filtered through our own consciousness Recommended reading Mindscience interviews with the Dalai Lama about neuroscience c Identity position doubleaspect theory Mental and physical quotstuffquot are just two aspects of the same thing The position that is considered untenable byjust about everyone is strict dualism Descartes said that mental and physical processes occur at distinct levels of reality that do not interact except at one point in the universe the pineal gland solipsism the assumption that I alone exist or I alone am conscious lll Heredity and environment Two main ways to study heredity a twin studieswe compare identical and fraternal twins and also twins and nontwin siblings b adoption studies compare the traits of adopted children with their adoptive and biological parents How do genetics affect behavior a DirectlyOur genetic makeup predisposes us to behave in certain ways eg criminal behavior IQ mental illness b lndirectly Our genetic makeup causes us to shape our environment in ways that affect our behavior at least by magnifying certain tendencies Why is it difficult to sort out heredity and environmental influences eg prenatal influences We don39t know if children39s behavior is due to their genetic makeup or the environment in which they were conceived and raised which is also indirectly related to their genetic makeup Phenyketonuria PKUGenetic inability to metabolize phenylalanine an amino acid This amino acid builds up in the body and can poison a child impairing development leaving a child mentally retarded and irritable Environmental conditions can have a moderating effect on this disorder lf PKU is detected early enough the child can be put on a special lowphenylalanine diet that will minimize brain damage This diet avoids meat eggs certain grains aspartame NutriSweet and dairy Diathesisstress model of mental illness A diathesis is a predisposition towards certain mental health issues such as depression But it is usually an environmental stressor that leads to the display of symptoms IV Evolution Four misconceptions about evolution 1 The use of disuse of some structure or behavior causes an evolutionary increase or decrease in that feature Lamarckassumed incorrectly that acquired characteristics could be inherited 2 Humans have stopped evolving 3 Evolution means improvement All it REALLY means is improved fitness which has to do with procreation and the development of the next generation 4 Evolution acts to benefit the individual or the species Neither of these is true Evolution benefits the genes Darwin39s theory of natural selection was influenced by the economic theories of his era which were based on the strength of competition And so his theory emphasizes competition over cooperation How does evolutionary theory account for altruistic behavior a reciprocal altruismanimals help those who them in return b kin selection animals act in ways that benefit their relatives even if those relatives are not necessarily progeny
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