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Final Exam Review

by: Lucy Stevens

Final Exam Review PSYCH 3240

Lucy Stevens
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Detailed notes from the entire semester
PSYCH 3240
Dr. Claudio Cantalupo
Study Guide
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This 32 page Study Guide was uploaded by Lucy Stevens on Saturday April 23, 2016. The Study Guide belongs to PSYCH 3240 at Clemson University taught by Dr. Claudio Cantalupo in Spring 2016. Since its upload, it has received 15 views. For similar materials see PSYCH 3240 in Psychlogy at Clemson University.

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Date Created: 04/23/16
Final Exam Review 4-27-16 *Chapter 1- What is Biopsychology? -Neuroscience: study of the nervous system -Biopsychology: study of the relationship between body and behavior -Model: proposed mechanism for how something works -Mind-Body Problem: what is the mind and how does it relate to the brain The mind is a collection of things that the brain does; it does not actually exist. -Monsim: the mind and the body is created of the same thing a) Materialistic Monism: the body, mind and everything are physical b) Dualism: separates the mind and body -Descartes: French Philosopher who explained brain’s activity using the hydraulic model and concluded that animal spirits ran through the body to control it -Galvani, Fritsch, Hitzig performed many experiments that showed that nerves were operated by “electricity.” -Hemholtz measured speed of conduction in nerves and knew that nerves operated electrically Localization Issue: Determining that specific functions are carried out by different parts of the brain -Phrenology: brain function determined in specific areas -Equipotentiality: brain function determined by extent of damage -Gene: transmits characteristics and directs cell processes -Chromosomes: 23 pairs (46 total) located in the nucleus -Female: XX Male: XY -Zygote: fertilized egg -Embryo: first 8 weeks -Fetus: after 8 weeks -DNA: genetic information -Dominant and Recessive Alleles -Genotypes: combination of genes -Homozygous: AA/aa -Polygenic: characterizes determined by many genes -X-Linked: characteristic on the X chromosome of an unpaired gene; affect more males than females Genes and Behavior -Charles Darwin -Human Genome Project -Children share 1⁄2 of their genes with each of their parents. -Natural Selection Heredity and Environment -Heritability: percentage of the difference within a certain characteristic caused by genetic influences. Is greatest for height. If everyone all had the same genes, then the heritability would be 0%. -“We influence dispositions, not destinies.” This is because genes only have partial influence. Phenotypes: the exposed characteristic Heterozygous: Aa *Chapter 2- Communication Within the Nervous System Neurons: Specialized cells that receive information and send it to other cells; Carry information within in the brain and throughout the rest of the body; about 100 million neurons in the brain 1. Motor Neurons (output neurons): Receive information from the other neurons Carries information to muscle or gland cells 2. Sensory Neurons (input neurons): Receives a particular type of sensory information Carries information to other neurons 3. Interneuron: Connects one neuron to another in a particular part of the central nervous system (CNS) • Glial Cells: cells that provide structural and functional support for neurons • Oligodendrocytes: build myelin around axons in the brain and spinal chord (CNS) (The membranes of most cells are made of fat) • Schwann Cells: build myelin around axons in the peripheral nervous Neural Membrane: critical for the neurons ability to carry information -consists of a phospholipid bilayer where protein molecules are sometimes embedded. Protein Molecules Channels: molecules move down a gradient Pumps: molecules are pushed against the gradient Resting Potential: difference in electrical charge between the inside and outside of the membrane of a neuron at rest. more potassium inside the neuron and more sodium outside the neuron Sodium Potassium Pump(Na+/K+) Pump: repeatedly moves 3 Na+ out of the neuron and 2 K+ inside the neuron at rest. K+ Ions: attracted inside by *Electrical Gradient , and attracted outside by the Concentration Gradient. *Concentration Gradient is slightly stronger than the Electrical Gradient, but they are basically in balance with each other. *These two forces are independent of each other, but they act at the same time. Na+ Ions: attracted inside by BOTH Electrical Gradient and Concentration Gradient. *Electrical gradient is slightly stronger than the Concentration Gradient, but they are basically in balance with each other. *Hyperpolarization: reserved for any increase in polarization (going away from 0) *Depolarization: reserved for any decrease in polarization (going towards) Massive influx of sodium into the neuron Most of the potassium channels start opening (not as rapidly as the sodium channels) and potassium moves outside Sodium Channels shut close and no more sodium can enter the neuron. (by now, the potassium channels are fully open) Now lots of potassium leaving the neuron. Sodium channels are still closed. Then there is some hyperpolarization caused by potassium channels starting to close slowly which causes excess leaking outside of potassium. Neuron is loosing even more positive charge and becoming more negative. Pumps open and the normal distribution is acquired. *Absolute Refractory Period: The neuron does not react to any stimulus because the sodium channels will not open. Lays down a “speed limit” for the neuron in terms of how many times that neuron is able to fire over time. *Relative Refractory Period: Won’t produce an action potential unless the stimulus is stronger than normal. *Rate Law of Action Potentials: Intensity of a stimulus is encoded by the rate of action potentials. *As the stimulus gets stronger, the neuron goes faster. Ex: Hearing a louder sound or seeing a brighter light the neurons will fire faster in your brain. *Spontaneous Activity: firing of a neuron in absence of environmental stimulation *Action Potential: you need a passive (graded) potential that will end up changing the electrical difference within the membrane *The All or None Law: the height of the action potential curve is constant. -amplitude depends on the intensity of the stimulus (unlike action potentials) and don’t go very far Axon Hillock: where the axon comes out of the cell body; first region of the neuron where you can detect an action potential. 1) There is a massive influx of positive charges, which sets of massive depolarization currents going left and right. The next region of membrane is depolarized and reaches threshold. Then an influx of sodium goes into the second part of the membrane. 2) This next section was at rest, but is now experiencing the up phase of action potential. The first section is now permeable to potassium and experiencing the down phase of action potential. 3) The process keeps repeating over and over. *Myelination and Conduction Speed of Action Potentials 1) Increase the neuron width a. Squid have axons that are huge and allow them to speed up their action potentials. 2) Myelin produced by glial cells (oligodendrocytes and Schwann) Nodes of Ranvier: uncovered parts of the axon not covered in the myelin sheath. **Movement of Signal through Neuron Covered in Myelin: Na+ channels open (action potential) Depolarization spreads within the exon very quickly. At the next node, the action potential is triggered. This continues to happen at each node as the action potential jumps from one to another. *The graded potentials happen within each myelin sheath. *Saltatory (Jumping) Conduction: 15 times faster and a lot cheaper than in un-myelinated axons *Communication between Neurons Exocytosis Calcium coming in is the first step of the long chemical process of transfer between neurons. The vesicles move toward the membrane and converge with it Neurotransmitters released into the cleft. (-70 mV at this point) (more sodium is outside than in. More potassium is in than out. ) *On the postsynaptic membrane there are channels that are NOT voltage activated. *They open if one or more molecules attach to them (Lock and Key process) *Polarization begins changing as the channels are opened and closed. 4. Now the postsynaptic neuron is active. Sodium channels open and sodium (Na+) starts to go in and membrane potential starts depolarization (moving toward 0 mV). Excitatory Postsynaptic Potential (EPSP): postsynaptic membrane becomes partially depolarized. Most likely, the action potential will occur at the post-synaptic neuron or the axon hillock and there is a higher rate of firing. Inhibition -Now assume the potassium channels open up and the potassium flows out. -The membrane potential moves away from the threshold and shows hyperpolarization. Inhibitory Postsynaptic Potential (IPSP): postsynaptic membrane exhibits hyperpolarization. *It is unlikely that the action potential will occur at the axon hillock or the post-synaptic neuron and there is a decreased rate of firing. Postsynaptic Integration a) Most neurons receive EPSPs and IPSPs from about 1000 other neurons. b) SPSPs and IPSPs combine at the axon hillock c) EPSP and IPSP are graded potentials Type of Synapses: i. Temporal Summation ii. Spatial Summation 1. Axosomatic Synapse: Located between the terminal button of one neuron and the soma of another neuron. 2. Axodendritic Synapse: Located between the terminal button of one neuron and the dendrite of another neuron. 3. Axoaxonic Synapse: Located between the terminal button of one neuron and the terminal button of another neuron. a. The neurotransmitters form the one axon can affect the membranes permeability to calcium on the other neuron b. Presynaptic Excitation: an increase in the release in neurotransmitters by the presynaptic neuron. c. Presynaptic Inhibition: a decrease in the release of neurotransmitters by the presynaptic neuron Neurotransmitters *Chemical signals that are released by one neuron at the synapse and that affect other neurons. *Know the table of neurotransmitters found at the end of chapter two. *GABA is important (Hint-Hint) *Know most prevalent and what they do. Drug: a chemical that comes from the outside that has an affect on your nervous system. Depending on the effects you classify the drug as an agonist or an antagonist . a) Agonist: a chemical that mimics or increases the effect of a neurotransmitter . b) Antagonist: a chemical that blocks the effect of a neurotransmitter *Chapter 3- The Organization and Functions of the Nervous System Central Nervous System (CNS): Made up of the brain and the spinal chord and where most of the processing takes place. CNS is made up of one type of neurons called interneurons. Peripheral Nervous System (PNS): made up of cranial nerves and spinal nerves. Cranial Nerves: connect to the brain Spinal Nerves: connect to the spinal chord *A neuron is a single cell. *A nerve is a bundle of axons of many neurons in the PNS. *A tract is a bundle of axons of many neurons in the CNS. Anatomical Direction of the Nervous System *Neuraxis: imaginary line drawn through the center of the CNS from the bottom of the spinal chord to the front of the forebrain. The Brain Horizontal Section Sagital Section Coronal Section Development 3 WEEKS: Part of the tube grows at different rates. You can see the 3 major portions emerging. Forebrain, Midbrain, hindbrain. 7 WEEKS: cranial nerves begin to form. 11 WEEKS: the forebrain has taken over in terms of development. The other parts aren’t developing as fast. At BIRTH: the hindbrain has expanded. All three parts expanded at different rates, so that they end up as recognizable organs. Cerebral Hemispheres Cortex: Outer surface that is wrinkled with grooves and ridges Ridge=gyrus Groove=sulcus GRAY MATTER and WHITE MATTER *A very large sulcus is called a fissure. *A central fisher separates the left and right hemispheres. *Clusters of gray mater are called nuclei. Roles of the Lobes 1. Frontal Lobe: Precentral Gyrus (Primary Motor Cortex): Controls voluntary movement. One hemisphere controls the opposite side of the body, which explains how you can have paralysis on one side of the body. Located in front of the Central Sulcus. Topographical organization of body muscles. Motor Homunculus Broca’s Area: Controls speech and articulation Grammatical structure Lateralized to the left area Lesion to the right side Broca’s Area is less likely to cause speech issues. Broca’s Aphasia Impaired word production Unimpaired word comprehension Prefontal Cortex: Involved in planning, impulse control, and decision making Composed of highly sophisticated neural function. Associative cordial region: involved in performing higher level processing “Central Executive” part of the brain 2. Parietal Lobe: Postcentral Gyrus (Primary Somatosensory Cortex): Processes skin senses, body positioning. One hemisphere serves the opposite side of the body; Topographical Organization Association Cortex: further sensory information processing; Integrates information from other senses; Locations of objects in space Unilateral Neglect: ignoring objects on the opposite side to the damage. Not a perceptual problem 3. Occipital Lobe: processes visual stimulations Primary Visual Cortex Processes simple features (orientation) Topographical organization 4. Temporal Lobe: Auditory Cortex: first set of neurons that receive hearing information from the ears. Located at the top part of the temporal lobe Wernicke’s Area: more involved in the comprehensive aspects of speech. Inferior Temporal Cortex: main lower part of the temporal lobe involved in visual identification of certain objects Other Forebrain Structures: a) Cerebral Hemispheres b) Corpus Callosum: large band of myelinated axons c) Thalamus: sensory relation station that relays incoming sensory information to the cortex d) Hypothalamus: Sits under the thalamus and is the hub for fundamental drives Specific parts coordinate emotional and motivational functions (sex, eating, emotion) Controls the pituitary gland (master gland of the body) which then controls the rest of the endocrine system (hormones) Axons of neurons connect the hypothalamus to the pituitary gland Ventricles: brain cavities that contain cerebrospinal fluid and carries materials to the CNS; 4 total ventricles. 2 lateral ventricles, and 2 other ventricles. Technically just cavities in the brain with fluid Midbrain: relatively small area compared to the other two areas a) Tectum (dorsal side): b) Superior Colliculus: vision (eye movement). When neurons are active here, you see nothing at all. Controls eye movements. c) Inferior Colliculus: hearing and location of sounds d) Tegmentum (ventral side): controls movement a. Substania Nigra: Dopamine-producing neurons. Tend to die out because they are overactive. Related with Parkinson’s Disease b. Ventral Tegmental Area: plays the part in the rewarding effects of drugs, food, sex Hindbrain: a) Pons (bridge): sensory neurons pass through on the way to the thalamus. Motor neurons pass through between the cortex and cerebellum Part of the Reticular Formation (sleep and arousal) b) Cerebellum: involved in motor coordination and balance, cognitive function, motor learning c) Medulla: involved in life-sustaining functions like heart activity and breathing. Lesions in this area are usually fatal very quickly. Spinal Chord: cable of neurons a) carries signals from the brain to muscles and glands b) carries sensory info from the periphery to the brain c) hub for reflect arcs which are neural pathways that produce reflex acts Reflex Arc: Neural pathway that controls the reflex act Reflex Act: simple, automatic response to a sensory stimulus (muscle contraction or grand secretion) Ganglion: contains the cell bodies Spinal chord: the neural part Meninges: these membranes wrap spinal chord and brain tightly. Provide structural support and protection. Cerebrospinal fluid between *Spinal chord and backbone are different. ****Vertebrae form the spinal column, which is part of the skeletal system ****Spinal chord is NOT the spinal column. It is part of the nervous system. Blood-Brain Barrier (part of the vascular parts of the body) -Prevents potentially harmful toxins and substances form reaching the CNS. *Not all toxins are stopped by the blood-brain barrier. If it is a fat-soluble toxin, the barrier is useless. *Some regions of the brain are actually not covered by the blood-brain membrane. -The Area Postrema (of the Medulla): induces vomiting when some toxins are in the bloodstream. *CNS-Brain and spinal chord *The PNS connects the CNS to the rest of the body. 12 pairs of cranial nerves (come out of the brain stem) 1 pairs of spinal nerves (come out of the spinal chord) Nerve: a bundle of axons PNS Somatic-made of axons (both motor and sensory). Motor neurons: involved in carrying signals from CNS to the muscles. Sensory neurons: bring signals from muscles to the CNS Autonomic- involved in basic regulating body functions, which happens at the level of reflexes. Controls smooth muscles, heart, glands, etc. a) Sympathetic Speeds up general body activities (heart beat, respiration, blood pressure and sweat glands) Originate from the middle of the spinal chord Passes through the sympathetic ganglion chain b) Parasympathetic: Slows body processes down Originate from the ends of the spinal chord *Both are active all the time to some degree.* Body’s activity represents a balance of the two Development of Nervous System 1) Proliferation a. Neurons divide and multiply at extreme rate 2) Migration a. Neurons move to their final destinations by climbing radial glial cells 3) Circuit Formation Neurons send developing axons to make synapses with their target cells Growth cone develops at tips of developing axons and move towards final targets using chemical/ molecular signals 4) Circuit Pruning Extra neurons that have developed die Eliminates large numbers of extra synapses that refines the organization 5) Plasticity Ability of synapses to be modified by experiences like learning Decreases with age-cortical areas are more likely to retain their plasticity. The brain never stops developing Chapter 5- Drugs and Addiction *Drug- any chemical substance that can change the body and the physiology of the body 1. Psychoactive Drugs: have psychological effects Agonist: drug that mimics or helps the effect of a neurotransmitter Antagonist: reduces or blocks the effects of a NT *Drug (abused) Terminology- 1. Addiction: Must show 3 criteria to be considered “addicted” Preoccupation with obtaining drug (person or individual devotes lots of time and effort to getting access to the drug) Compulsive use of drug High tendency to relapse after quitting 2. Withdrawal: any negative reaction (physiological and physiological) experienced by an individual when he/she tries to quit or cant get access to the drug for sometime Symptoms often show the opposite effects of drug (EX: withdrawal from elation- producing drug…depression) 3. Tolerance: behavior phenomenon where increasing amounts of the drug are needed to produce the same results Mostly due to reduction in the number and or the sensitivity of receptors to the drug *Drug Types- 1. Opiates: derived from a plant called Opium Poppy a. Opium b. Morphine c. Heroine d. Codeine *Opiates have a variety of effects: a. Analgesic (pain relieving) b. Hypnotic (sleep inducing) *Side Effect (addictive) a. Heroine: *Opiates bind to opiate receptors: knew about the drug and its effects before they knew about the receptors in the body *Act as agonists of endogenous opiates—endorphins (pain relief) 2. Depressants- reduce activity of CNS Ethanol (“Alcohol”) Complex Action: High Doses- sedative and hypnotic (calming) Low Doses- stimulate Addictive Withdrawal involves tremors, anxiety, mood and sleep disturbances (delirium tremens in worst cases- hallucinations, seizures, death) Acts as antagonist of glutamate (most prevalent NT) Acts as agonist of GABA by binding to GABA receptA s Facilitates opening of Chlorine channels causing hyperpolarization of postsynaptic membranes Barbiturates: derivate of barbituric acid Complex Action High Doses: sedative and hypnotic Low Doses: inhibits cortical centers that inhibit behavior (Ex: talkativeness) Act as antagonist of glutamate Act as agonist of GABA by binding to GABA A In high doses can open Chlorine- channels even without GABA, which is potentially very dangerous causing coma or death Benzodiazepins Similar to Barbiturates but safer Cannot open Chlorine channels on their own Produce anxiolytic (anxiety-reducing), sedative, anti-seizure, and muscle-relaxing effects Addictive 3. Stimulants: increase activity of the CNS Cocaine Produces euphoria, increased alertness, relief from fatigue Acts as an agonist of dopamine and serotonin by blocking their reuptake Addictive; withdrawal symptoms include depression and anxiety Amphetamines Synthetic drugs (methamphetamine: speed, crank, crystal) Produce euphoria, increase in confidence, alertness, and concentration Acts as an agonist of dopamine and norepinephrine by increasing their release in the synaptic clef In high doses can cause hallucinations, delusions and other psychotic-like symptoms Nicotine Primary psychoactive and addictive agent in tobacco Complex action- Short puffs: stimulating effect Long puffs: depressant effect Acts as agonist of acetylcholine (activates muscles, increases alertness) Addictive, withdrawal symptoms include nervousness, anxiety, drowsiness, lightheadedness, headaches Caffeine Produces arousal, alertness and decreased sleepiness Acts as agonist of dopamine and acetylcholine by increasing their release in the synaptic cleft Withdrawal symptoms include headaches, fatigue, anxiety, shakiness, craving 4. Psychedelics: Cause perceptual distortions of objects, time, self, often accompanied by euphoria LSD Similar to serotonin- binds to serotonin receptors Ecstasy (MDMA) Causes release of dopamine and serotonin- kills serotonin neurons in monkeys Angel Dust (PCP) Produces schizophrenia like symptoms in humans Inhibits glutamate receptors Increases activity of dopamine pathways 5. Marijuana Dried and crushed leaves and flowers of Indian hemp plant Major psychoactive ingredient: THC Particularly concentrated in the dried resin of the plant-hashish THC acts as agonist of NT anandamide and 2-AG by binding to their receptors (cannabinoid receptors)- widely distributed in CNS Anandamide and 2-AG may play important role in the regulation of mood, memory, appetite, and pain perception Withdrawal symptoms are associated with stopping use (ex. irritability, anxiety, stomach cramps) Addiction 1. Preoccupation with obtaining drug 2. Compulsive use of drug 3. High tendency to relapse after quitting Different areas of the brain seem to be involved in withdrawal and addiction. Withdrawal: PeriVentricular/PeriAqueductal *Ventral Tegmental Area (VTA) -Important for the establishment of an addiction *Medial Forebrain Bundle *Nucleas Accumbens MesolimboCortical Dopamine System (MDS): Main areas of the brain for reward and addiction *Drugs come in and highjack our hardwire system and just mess us up. 1. MesolimboCortical Dopamine System 2. Nucleus Accumbens (NAcc): rich in dopamine receptors Nearly all abused drugs increase dopamine levels in NAcc Reducing dopamine level in NAcc decreases rewarding effects of drugs *Increase in dopamine in NAcc may be the neural basis for rewarding effect of drugs *May be part of a general reward system. *Electrical stimulation of the Medial Forebrain Bundle is rewarding in rats -Increases dopamine level in NAcc *Involved in rewarding effects for behaviors of basic importance (Ex: sex, feeding) -Increases dopamine level in NAcc (both humans and non) *Apparent paradox: lower number of dopamine receptors in drug users a) Possible innate trait b) Reward deficiency syndrome c) Vulnerability to drug use d) Dopamine activity in MDS cannot account for all addictions Benzodiazepines affect Glutamate and GABA levels Many continue to use drugs even when the effects are no longer pleasurable e) Possible important role in learning Just seeing drug paraphernalia can evoke craving in drug addicts Dopamine levels in MDS may act as “teaching signals” emphasizing importance of relevant stimuli Ending Dependence on Drugs Overcoming withdrawal symptoms Fighting against relapse Pharmacological Treatments for Dependence Agonist treatments o Replace addicting drug with another that has a similar effect Antagonist Treatments o Involve drugs that block effects of addicting drug § GABA rA eptor blocker limits effect of alcohol Aversive Treatments o Cause negative reaction when person takes the addictive drug Antidrug Vaccines o Finding ways to stimulate the persons own immune system to react to the drug molecule or systems that respond to the drug molecule before it can have its normal effect. o Stimulate immune system to produce antibodies that break down the drug Pharmacological treatments for drug addiction still somewhat controversial. Chapter 6 Motivation and Regulation of Internal States Motivation (Old Definition): set of factors that initiate, sustain and direct behavior. Motivation (New Definition): Inability to explain behavior solely in terms of external stimuli. Theoretical Approaches to Motivation • Instinct: complex behavior Automatic and Unlearned Occurs in all members of the same species in virtually the same fashion Instincts are much more complex than reflexes (like sneezing or moving hand away from something hot) Simplest theory of motivation is instinct • Drive Theory (leading theory) The body actively maintains physiological systems in condition of balance…HOMEOSTASIS Departure from Homeostasis…Aroused Condition Drive: Motivates the organism to engage appropriate behavior (Ex: eating, drinking, seeking warmth) ON TEST: Does reflex=instinct?? NO!! Reflexes are too simple. • Incentive Theory Individuals are motivated by external stimuli, not just internal needs Money, grades= incentives • Arousal Theory Individuals are motivated to maintain a preferred level of arousal Different people have different “optimal” levels of arousal • Drive Theory (Revised) Drives=conditions of the issues Drives=states of the brain Better accounts for sexual behavior, even eating behavior Simple Homeostatic Drives Many physiological systems maintain a given condition within a narrow range (ex: body temperature, energy reserves) • Basic notion of drive theory is basically true. Control systems- operate on negative feedback loop Feedback= process whereby some proportion the output of a system is passed (fed back) to the input which influences the output The nervous system has an input and output side Negative Feedback Loop: feedback stabilizes the system at a given set point. Temperature Regulation Heterothermic animals (reptiles)- externally regulated body temperatures Homeothermic (endothermic) Animals (Mammals)- adjust body temperature internally Anterior Commissure: connects the left and right side of the brain. A few nuclei on the ventral posterior side of the hypothalamus known as the mammillary bodies. Called this because Preoptic Area: contains warm and cold sensitive cells that induce the heat-reducing or heat-conserving processes. • Thirst Osmotic Thirst: water content decreases inside the cell Eating salty food: higher concentration of NaCl in blood than inside the cell Hypovolemic Thirst: blood volume decreases due to loss of extracellular water These two processes are regulated by separate processes! Osmotic Thirst: OVLT. Where you find the most important receptors for osmotic thirst Neurons start changing their signaling as soon as they start loosing too much water. Median PreOptic Nucelus: when neurons here become active, that is when you start feeling thirsty. Hypovolemic Thirst: some receptors are not found in the brain at all, but in the heart. Baroreceptos: cells located in the heart and are sensitive to blood pressure. Send signals through an axon up to the nucleus of the medulla. Nucleus of the Solitary Tract (Medulla): become activated and cause thirst Renin: hormone that stimulates the secretion of another hormone called angiotensin II. Sub Fornical Organ: when cells are activated here, they tell the hypothalamus and then you being feeling thirsty Hunger More complex drive than temperature regulation and thirst Set point can undergo dynamic and prolonged shifts (ex: obesity) Involves the need for variety of different and specific kinds of nutrients Dietary section: must distinguish between nutritious and non-nutritious (or toxic) foods…role of taste Taste 5 primary tastes- sweet, sour, salty, bitter, umami More complex taste sensations are combinations of 5 primaries Nucleus of the Solitary Tract (Medulla): sense travels here after hitting the taste buds on the tongue and then heads to the insula Insula (Cerebral Hemisphere): sometimes known as the 5 lobe of the brain. Neurons here become active and you become consciously aware of the tastes. Major hubs for large scale brain networks. Contributes to dietary selection in three additional ways Sensory-Specific Satiety: the more of a specific food a person eats, the less appealing a food becomes Encourages a varied diet èbalanced diet Controlled by the Nucleus of Solitary Tract (NST) in the medulla. Learned Taste Aversions: the avoidance of foods associated with illness or poor nutrition Learned Taste Preferences: preferences for flavor of foods that contain important nutrients (e.g. Vitamin B) Animals learn to prefer the flavor of a food enriched with thiamineèpresumably makes them feel better The Digestive Process Begins with saliva in the mouth by enzymes HCL and pepsin break it down in the stomach If food irritates the stomach, regurgitation occurs If no irritation occurs, toxins reach the area postrema of brain-induces projectile vomiting Most digestion occurs in the small intestine (especially the duodenum) Carbohydratesèglucose Proteinsèamino acids FatsèFatty acids and glycerol Large intestine reabsorbs water from the food before it is excreted from the body. The Two Phases of the Feeding Cycle Absorptive Phase: Glucose increases Parasympathetic activation Pancreas secretes insulin Glucose enters body cells; glucose stored in the liver and muscles as glycogen; fat stored in adipose cells as triglycerides Fasting Phase: Glucose decreases Sympathetic activation Pancreas secretes glucagon Glycogen transformed to glucose (for brain); stored fat released as fatty acids (for body) and glycerol (for brain, after conversion to glucose) Two Major Signals for Hunger Glycoprivic Hunger: deficit in glucose Lipoprivic Hunger: deficit in fatty acids Low Glucose and fatty acids signaled via vagus nerve to the Nucleus of the Solitary Tract (NST) and the Area Postrema (both in the medulla) Information is then relayed to Arcuate Nucleus (AN)èParaVentricular Nucelus (PVN) and Lateral Hypothalamus (LH): when neurons here become active we become hungryèIncrease in the release of neuropeptide Y in LH and PVN. Powerful stimulate for eating and reduces metabolism (and even sexual motivation) Another powerful stimulant for eating: Grelin (produced by the stomach and gets it into the blood supply where it will reach the regions in the hypothalamus and will activate the AN; this then activates the PVN and the LH which causes you to feel hungry) Signals that End Eating o Stretch receptors in the stomach-signal via vagus nerve to medulla (NST and Area Postrema)èdecrease of neuropeptide Y in PVN and LH. Then you start to feel less hungry o Cholecystokinin (CCK)- peptide hormone released when food passes through the duodenumèvagus nerveèmedullaèdecrease of neuropeptide Y in PVN and LH o Peptide YY 3-36 PYY) intestine-secreted hormoneèreaches Arcuate Nucleus through bloodstream- slower action than CCK o High levels of nutrients in blood-detected by liverèvagus nerveèmedulla (NST and area postrema)èdecrease of neuropeptide Y in PVN and LH Long Term Regulation of Body Fat o Leptin (hormone secreted by fat cells) § Amount of leptin in blood is proportional to % of body fat § Increased leptin in bloodèdecrease in neuropeptide Y in PVN and LH § Decreased leptin in bloodèincrease in neuropeptide Y in PVN and LH § Leptin levels is about 4 times higher in obese than non-obese peopleè may have fewer active leptin receptors in PVN and LH Chapter 7 -Biology of Sex § Is sex a physiological drive (like hunger and thirst)?? o Main difference: sex is not essential for survival of the individual o Similarities: § Arousal and satiation § Role of hormones § Involvement of specific brain areas Phases of Sex Cycle 1. Excitement 2. Plateau 3. Orgasm 4. Resolution Refractory Phase (more specific to males) -Somewhat related to sensory-specific satiety Sensory-Specific Satiety: the more of a specific food a person eats, the less appealing the food becomes -Encourages a varied diet Coolidge Effect (Male Specific): quicker return to sexual arousal for a male when a new female is introduced -Observed in many species -“Cheap sperms, expensive eggs” theory Roles of Hormones on Sexual Activity Sex Hormones • Androgen: male characteristics and functions o Testosterone= major sex hormone in males • Estrogen: female characteristics and functions Testosterone and Sexual Activity Evidence from castration (removal of the gonads) studies Sexual behavior decreases; clearly shows that hormones are very important variables for triggering sexual behavior Testosterone appears necessary for male sexual behaviors, but amount required is minimal Females initiate sex more at mid-cycle when both estrogen and testosterone levels are elevated Testosterone may be more important than estrogen for this in women Testosterone increases as a result of sexual activity in both males and females. Cause-effect relationship by the way testosterone and sexual activity is still unclear Brain Structures and Sex • Network of brain structures are involved in sexual activity • Medial PrOptic Area (MPOA) of Hypothalamus Stimulation of MPOA in rats è increased copulation Sexual Dimorphic Nucleus of MPOA Larger in male rats Depends on prenatal exposure totestosterone Medial Amygdala: active during copulation in both males and females; stimulation causes dopamine release in MPOA VentroMedial Nucleus (VMN) of Hypothalamus: active during copulation in females; destruction reduces responsiveness to males Neurotransmitters and Sex • Dopamine and Serotonin increases MPOA in rats. • Norepinephrine increases in men and women during sex. • Dopamine increases in the Nucleus Accumbens o In male rats it increases also with new female (Coolidge Effect) Sensory Stimuli and Sex • Interplay of internal (hormone) conditions and external stimuli. Tactual; Auditory; Visual Olfactory (smell) Pheromones= airborne chemicals released by an animal that may have a physiological or behavioral effect on another animal of the same species. What about people?? VomeroNasal Organ (VNO): we do have in human noses as well. It is microscopic. Very large in animals like cats and dogs. Pheromones are detected by the VNO VNO sends signals to MPOA and VentroMedial nucleus to hypothalamus. McClintock study on menstrual synchrony Found that women living together had menstrual cycles at the same time. Menstrual synchrony in human females due to pheromones. Humans have a VNO too Microscopic in size Generates electrical potentials to suspend pheromones Experiment: • Men rate photographs and voice recordings of women higher when sniffling inhalers containing suspected pheromones from the women. • Men rate t-shirts of more attractive women highest on sexiness-smell itself not pleasant • Men using after-shave containing suspected male pheromone report more sexual activity than controls. • Pheromonal influence on sexual behavior of humans is still controversial. Emotion and the Nervous System • *E- Motion: E represents movement from inside to the outside. • *Ex (Out) Movere (to move) • *Movement of mind (soul) (“feeling” ex: happiness) èBody’s responses (smiling, higher heart rate) • *Smiling controlled by the somatic nervous system • *Higher heart rate controlled by the autonomic nervous system (Sympathetic) • *Relationship between emotional experience and body’s response is unclear/controversial. o “I feel sad because I cry” (rather than “I cry because I feel sad”) • James-Lang Theory of Emotion (late 1800s): o Perception of specific patterns of physiological arousalè specific emotional response o The change in your body comes first (heart rate increasing, sweating) • Cannon’s criticism (1920): autonomic nervous system responds the same way in different emotionsè perception of physiological responses cannot account for variety of emotional experiences that we feel • Schachter and Singer’s (1962) Cognitive Theory: Identification of emotions relies on cognitive assessment of the external stimulus situation *Distinctive patterns of autonomic activation among different emotions -Anger and sadness both elevate heart rate, but only anger involves also motor activation *Facial expressions as a source of emotional feedback -Holding a pen in your mouth and the Far Side cartoons study: *Both Cognitive assessment of external stimulus physiological feedback play a role in emotion. Emotion and the Nervous System Limbic System 1. Hypothalamus: electrical stimulation in animals produces threatening or defensive behaviors (cats hissing, bared teeth and claws); electrical stimulation in humans evokes feelings of rage, fear, and pleasure 2. Septal Nuclei: electrical stimulation in humans evokes feelings of pleasure (particularly sexual) 3. Amygdala: involved in perception of facial expressions and emotion (particularly fear); damage to amygdala removes fear and aggression in animals; direct stimulation produces fear and aggression; anti-anxiety medications have some of their effect in the amygdala a. Plays a major role in fear and anxiety b. Fear= emotional reaction to a specific immediate threat c. Anxiety= apprehension about a future, and often uncertain, event 4. Circulate Gyrus: hub where many different brain networks converge a. Anterior Cingulate Cortex: combines emotional, attentional, and bodily information to bring about conscious emotional experience. Emotion and Prefrontal Cortex (PFC) *Lot of connections with limbic system (LS) *Use of emotional information from LS for making decisions -Damage to PFC: *Blunts emotional responding *Impairs ability to anticipate consequences of behavior (long-term consequences in particular) Emotion and Hemispheric Asymmetry • Left and right cerebral hemispheres can differ in: o Anatomical structure- structural asymmetry (ex: Broca’s area larger in left hemisphere than right) o Function performed- functional asymmetry (ex: left hemisphere more involved in linguistic functions than the right hemisphere) • Right hemispheres more involve din emotional expression o Facial expressions of emotion Emotion and the Nervous System *Movement of mind (soul) (“feeling” ex: happiness) èBody’s responses (smiling, higher heart rate) *Smiling controlled by the somatic nervous system *Higher heart rate controlled by the autonomic nervous system (Sympathetic) *Relationship between emotional experience and body’s response is unclear/controversial. James-Lang Theory of Emotion (late 1800s): Perception of specific patterns of physiological arousalè specific emotional response The change in your body comes first (heart rate increasing, sweating) Cannon’s criticism (1920): autonomic nervous system responds the same way in different emotionsè perception of physiological responses cannot account for variety of emotional experiences that we feel; Because of this, the James-Lang theory was basically abandoned Schachter and Singer’s (1962) Cognitive Theory: Identification of emotions relies on cognitive assessment of the external stimulus situation- physiological arousal contributes only to the sensation of the intensity of that emotion. “Epinephrine” experiments *Both Cognitive assessment of external stimulus physiological feedback play a role in emotion. Emotion and the Nervous System Limbic System Hypothalamus: electrical stimulation in animals produces threatening or defensive behaviors (cats hissing, bared teeth and claws); electrical stimulation in humans evokes feelings of rage, fear, and pleasure Septal Nuclei: electrical stimulation in humans evokes feelings of pleasure (particularly sexual) Amygdala: involved in perception of facial expressions and emotion (particularly fear); damage to amygdala removes fear and aggression in animals; direct stimulation produces fear and aggression; anti-anxiety medications have some of their effect in the amygdala Plays a major role in fear and anxiety Fear= emotional reaction to a specific immediate threat Anxiety= apprehension about a future, and often uncertain, event Circulate Gyrus: hub where many different brain networks converge Anterior Cingulate Cortex: combines emotional, attentional, and bodily information to bring about conscious emotional experience. Emotion and Prefrontal Cortex (PFC) *Lot of connections with limbic system (LS) *Use of emotional information from LS for making decisions Damage to PFC: Blunts emotional responding Impairs ability to anticipate consequences of behavior (long-term consequences in particular) Emotion and Hemispheric Asymmetry • Left and right cerebral hemispheres can differ in: o Anatomical structure- structural asymmetry (ex: Broca’s area larger in left hemisphere than right) o Function performed- functional asymmetry (ex: left hemisphere more involved in linguistic functions than the right hemisphere) • Right hemispheres more involved in emotional expression o Chimerical Faces: people are asked to rank § Find left chimerical faces to be more expressive; explained because the left side of the brain is more expressive than the right side of the brain. o Studies show that the right side of the mouth opens sooner, which indicates that the left side of the brain controls speech *Stress: o Condition in the environment that makes unusual demands on the organism o Internal condition: body’s response to a stressful situation *Stress as an adaptive response o Stressful situation è activation of the sympathetic branch of PNSè helps the organism cope with stress o Stressful situationèactivation of the Hypothalamus-Pituitary-Adrenal cortex axis o Group of structures that increase activation and energy levels *HPA Axis: o Hypothalamus o Anterior Pituitary o ACTH (through blood): Adrenal Cortico Tropic Hormone § hormone that targets the adrenal cortex o Adrenal Cortex: § Epinephrine and Norepinephrine which increases heart rate and increases glucose availability § Cortisol: Converts proteins to glucose, increases fat availability, and increases metabolism (energy) *Stress as an adaptive response o Short term stress è increases immune system activity o Immune System: cells and cell products that protect the body against foreign substances (bacteria, viruses, tumor cells) *Major Types of Immune Cells Macrophages: invest invaders; display antigens, which attract T cells T Cells: multiply and attack invaders B Cells: make antibodies, which destroy intruders Natural Killer Cells: attack cells containing viruses, certain kinds of tumor cells *Negative Affects of Stress (Long-Term) Memory impairment, appetite changes, decreased sex drive and energy, mood disruptions Decreased B cells, T cells, and Natural Killer cells, which makes illness more susceptible Increased blood pressureè increased risk of heart attack or stroke Hyperactivation of sympathetic nervous systemè heart goes into fibrillationè sudden cardiac death Decreased hippocampal volume and cortical tissue in brain (premature shrinking of neurons and cells) Probably caused by increased levels of cortisol and can induce memory impairment *Pain and Emotion o Pain is adaptive Congenital insensitivity to pain leads to repeated injuries and death Most individuals don’t end up living very long because they do things to hurt themselves. Level of pain perception influenced in some measure by context and culture Childbirth; different cultures rate childbirth pain differently Pain pathway heavily connected with limbic system Anterior Cingulate Cortex (ACC)è emotional aspect of pain Long-lasting pain activates the prefrontal cortex Planning of responses to painful stimulation (ACC is part of the cingulate gyrus) Chapter 9 Hearing and Language *Basic Concepts o Sensory System: set of components of the PNS and CNS involved in acquiring and processing of specific sensory information (e.g., auditory information) Sensation: acquisition of sensory information Perception: interpretation of sensory information (recognizing someone’s face; you don’t “sense” someone’s face) o Receptor: a cell that is suited by its structure and function to respond to a specific form of energy (e.g., sound) Often is a specialized neuron Transducer: device that converts energy from one form to another o Stimulus: specific energy form for which the receptor is specialized *Hearing Most people would say that vision is the most dominant sense of the body. Stimulus: vibration in a conducting medium (normally air) Source Sound: alternating pressure changes (compression- decompression) Pure Tones: single frequency Frequency: number of compression and decompression waves that occur over time; one compression followed by one decompression is one cycle Complex Sounds: combination of 2 or more frequencies Pitch: experience of the frequency of sound Loudness: experience of the intensity (i.e., physical energy of sound) Greater amount of air pressure change that the sound is producing, the louder the sound is Loudness and pitch are not independent in our ear experience because our ear has different levels of sensitivity to different frequencies. Frequency and amplitude are totally independent. Why do our ears show this preference for higher sensitivity for higher frequency sounds? -It’s an adaptation to the social environment that we live in. Human speech is normally on the high end of frequency range, which is why our ear is more sensitive. *Ear Subdivided into three parts 1. Outer Ear (Pinna): has bumps to detect the sound and let the brain know where the sound source is located. External Auditory Canal: serves as a resonator, so the sound gets amplified as it travels through the canal 2. Middle Ear Tympanic Membrane Ossicles (tiny little bone) Hammer, Anvil, and Stirrup Joint of interconnected bones that transfer the energy to the next part of the ear, but they also amplify because they act as a set of levers Energy is still vibration at this level. 3. Inner Ear: bony structure on the outside that is part of the skull Cochlea: basically a cylinder of bone that has been wrapped around onto itself. Inside filled with liquid with a couple of membranes running though Basilar Membrane: made of tissue and divides cochlea into two regions: Vestibular Canal and Tympanic Canal Vibrations cause movement in the liquid and membranes in the inner ear Round Window Basilar Membrane of Cochlea: Has cells on top of it. Cells reached by axons. 4 rows of hair cells on top called outer hair cells, and 1 row of inner hair cells Cilia: Hair part of the hair cell: fingerlike projections; Outer Hair Cells: embedded into the tectorial membrane; most numerous; their activity actually seems like they just sit there and do nothing not sending signals to the brain; cells acting more as muscles not receptors; many of these cells contain a contractile protein Inner Hair Cells: only one row of them; also have cilia that don’t make physical contact with the tectorial membrane; send most vibrational signals to the brain Tectoral Membrane (“Roof”): have hair cells **Membranes move when sound comes through, which causes cilia to vibrate and bend, which starts the transduction of vibration into an electrical stimulation. Electrical stimulation moves to the brain Cochlear Nucleus: First part of the brain to receive electrical stimulation from the cochlear; part of the medulla (hindbrain) (both sides of the brain receive information from both ears) Superior Olive: they look like an olive and there are two; part of the auditory pathway; receive information from the two ears; allows location of sounds; part of the medulla (hindbrain) Inferior Colliculus: part of the tectum midbrain and the auditory pathway; information goes through here before it reaches other higher areas; figuring out sound location; find the first neural networks that trigger responses to sound stimulation (like when someone says “POP” really loud and you jump) Medial Geniculate Nucleus of the Thalamus: Major sensory relaying station; Primary Auditory Cortex: first neurons that receive information from the ears; as soon as they become active you become consciously aware of hearing the sound (There are no pain receptors in the brain) *Auditory Cortex is topographically organized, which means that the auditory cortex looks like a map. Adjacent neurons in the cortex receive information from nearby receptors located on the basilar membrane. *Pitch Perception Experience of the frequency of sound *Pitch Perception: basilar membrane vibrates in synchrony with a sound frequencyè auditory nerve axons fire at the same frequency Problem: individual neurons can fire at no more than about 1000 Hz, but we can hear up to 16,000+ Hz. Volley Theory: groups of neurons can follow the frequency of a sound where a single neuron cannot; can even explain all of our voluntary sound perception Place Theory: sounds with different frequencies induce peaks of maximal vibration in different places on the basilar membrane (basilar membrane location matters); postulates a comparison of what frequency is coming in (high or low) and what place the basilar membrane vibrates Apex (of basilar membrane) is wide and floppy Base (of basilar membrane) is narrow and stiff Low frequency: cause maximum vibrations near the ape High frequency: cause maximum vibrations near the basee can think of the basilar membrane as a map of frequencies; as the frequency gets lower and lower it travels towards the apex. Tonotopic Organization of the Basilar Membrane Problem with Place Theory: with sounds below 200 Hz the whole basilar membrane vibrates equally- i.e., no peaks of vibration Primary Auditory Cortex: Contains a tonotopic map of the basilar membrane There is an orderly system of the tones *Pitch Perception 1. Frequency Theory 2. Place Theory Combine to form the Frequency-Place Theory *Frequency-Place Theory Synchrony of firing rate of auditory nerve axons with sound frequencyè pitch perception of sounds up to about 200 Hz. Place of maximal vibration on basilar membraneè pitch perception of sounds greater than 200 Hz. Able to hear pure tones (made of one frequency), which are not very common in nature; most of our auditory experience is not pure tones Perception of complex sounds: *Fourier (Harmonic) Analysis Any complex sound can be broken down into pure tones also known as component frequencies Frequency Fundamentals: Overtones: The basilar membrane of the cochlea acts as the Fourier/Harmonic Analysis Major role is played by the peripheral structure *Cocktail Party Effect • Ability to filter out meaningful auditory signals from a complex background • Possible role played by outer hair cells (found on the basilar membrane) • Outer hair cells actually mute some certain areas of the basilar membrane, which is how the cocktail effect works. *Sound Localization • It is important to be able to hear sounds, but it is equally important to know where that sound is coming from. • Binaural Cues: involve use of both ears; bran locates the source of a sound based on differences between the sound at two ears; three types 1. Phase Difference: a sound arriving from one side of the body is at a different phase of the wave at each ear (works for low- frequency sounds) Dog Head Cocking: response to auditory stimulation; behavioral way of being better able to perceive the sound 2. Intensity Difference Cue 3. Difference in Time of Arrival Cue Chapter 10-Vision Vision • Stimulus: visible light (form of electromagnetic energy)è its just a fraction of the electromagnetic spectrum The Eye • Retina: the neural tissue and photoreceptors located on the inner surface of the posterior portion of the eye; very large and intricate neural network; scientists think of it as part of the nervous system that sort of came away to be able to capture stimulus quickly o Three layers 1. Photoreceptor Layer: cones and rods 2. Bipolar Layer: bipolar, horizontal, and amacrine cells 3. Ganglion Cell Layer: ganglion cells o Receptors: cones and rods; specialized cells that receive photons and transform that type of energy into a completely different signal o Horizontal Cells: neurons that connect the retina in the horizontal direction; on the photoreceptor side of the middle layer of the retina o Bipolar Cells: neurons that connect the retina in the vertical direction o Amacrine Cells: similar to horizontal cells; tend to connect synaptically bipolar cells and other neurons in the horizontal connection; on the ganglion side of the middle layer of the retina o Ganglion Cells: axons of these cells come out of the cell body and cluster together to form a very large cable that is visible and is called the optic nerve; quarter of an inch thick o Fovea: center of the retina; labeled at 0° o Blind Spot: area of the retina where there are no rods or cones; no stimulus can be detected if one falls in this area; all of the axons coming out of the ganglion have no choice but to leave the eye at the back; the vertebrate retina is backwards which causes the blind spot; a better idea would to have the photoreceptors facing the source of the stimulus *Long strand of protein that is joined with the vitamin derivative called retinal. ON single photon flying along can change the chemical connection between the vitamin and protein. Photons are changed into an electrochemical signal. *When sodium channels are open: the neuron is now activated and excited and membrane is depolarized causing the release of inhibitory neurotransmitter and inhibits activity of the bipolar and ganglion cells, which is why you see nothing. *When light is present, photons arrive and start knocking off retinal vitamins from the protein, which is the first step of reactions that results in the closing of the sodium channels. When the NA+ channels are closed, the neuron is inhibited and becomes hyperpolarized which releases less of the inhibitory neurotransmitter and the signal travels to the ganglion cells as the firing rate increases. • Rods: are in charge of our night vision; provide no experiences in differences in color, only in difference sin brightness; contain photo-pigment Rhodopsin, which is very sensitive to light; they work best in dim light; NOT found in the fovea • Cones; much fewer cones than rods; contain photo-pigment Iodopsin, which is much less sensitive to light and requires a lot of light; our day light vision; come in three different kinds of iodopsin allowing us to provide information on different wavelengths coming into the eye; RED (long wavelengths), BLUE (middle wavelengths), and GREEN (short wavelengths) • Cones and rods are wired differently to the retina • Receptive Field: area of the retina with a patch of receptors from which a ganglion cell receives input Outside of the fovea, the rods are everywhere. The fovea is basically the cone system. The rest of the retina is the rod center. • Cornea: membrane that is in the front of the eye; thickness and curvature is the most important lenses of the eye; accounts for the eye’s ability to go to the retina • Lens: important for our ability to maintain an object on focus; for near- vision; series of transparent, onion-layer layers; shape can be changed by contraction of the ciliary muscles *Cones are found tightly packed into the fovea. *Receptive Field: area of the retina from which a ganglion cell receives input; typically very small; affects the activity of the neuron *Ganglion cells in the fovea have much smaller receptive fields than in the rest of the eye. *Fovea has the highest visual acuity. *Highest Visual Acuity- ability to distinguish the details of a visual scene *Visual Field: part of the environment that is registered in the retina; anything that you can see and anytime • Nasal Side • Temporal Side • Stimulus from left non-overlapping part of the visual field, the image will follow on the nasal side of the left eye and the temporal side of the right eye. • Stimulus from the right non-overlapping part of the visual field, the image will follow on the nasal side of the right eye and the temporal side of the right eye. Optic Chiasm: no complete mixing of the optic fibers; about half of the axons of the optic nerve pass over each other; part of the CNS Lateral Geniculate Nuclei (LGN): part of the thalamus that relays info to V1 Primary Visual Cortex (V1): part of the occipital lobe; contains first cortical neurons that follow stimulation of the retina Retinal Cortical Pathway: responsible for our conscious experience of seeing anything; not the only visual pathway in our brain Retinal Tectal Pathway: this other pathway; past the chiasm are fibers that go into the midbrain (Tectum) instead of to the thalamus; can experience blind sight; Binocular Field *Retinal Disparity: discrepancy in the location of an object’s image on the two retinas as a function of the objects distanceè detected by the visual cortex that helps with depth perception Color Vision: colors don’t actually exist; there is nothing absolute about color perception; provides a selective advantage Theories of Color Vision • Trichromatic Theory (von Helmholtz and Young) o All colors are the result of the processing of three “pure” colors: red, green, blue, each one detected by a specific receptor o Problem: yellow also appears to observe as “pure” color o Most people come up with 4 colors that they feel are “pure” to them, but there is no cone for yellow • Opponent Process Theory (Hering) o Explains color vision in terms of opposing processes in two specific receptors o Red goes with green and blue goes with yellow o Receptor for red and green: photochemical § Showing different lights have different effects o Receptor for yellow and blue: photochemical § If you shine yellow it should break down § If you shine blue light, that will build up the photochemical o Explains complementary colors and negative color aftereffect. Chapter 10 (Continued) 4-12-16 Ganglion cells are specific: one specific for red and green and one for blue and yellow; this brings us the experience of four primary colors and the Combined Theory of Color **Red light: causes an inhibitory effect onto the R-G ganglion cell (mainly the red cones) and signals to the brain that there must be red shinning on the eye. **Green light: excites the green cone, and higher rate of firing goes to the brain and translates the color. Red Light- inhibited Green Light- activated **Blue light: activates the blue cone and causes an excitatory effect onto the Y-B Ganglion cell and sends signals to brain and gives rise to color “blue.” **Yellow light: activates some of the red and green cone together because these wavelengths are much similar than that of the blue cones. Sends impulses to the R-G ganglion cell, and the impulses are canceled out because one is excitatory and one is inhibitory. Red nor green are “seen” and ganglion still fires at resting state. This has an effect on the R-B Ganglion cell by inhibiting it, which causes yellow. Inhibit R-G Ganglion Cellè RED Excite R-G Ganglion Cellè GREEN Excite Y-B Ganglion Cellè BLUE Inhibit R-G and Excite R-G, which inhibits Y-Bè YELLOW Receptive Fields of Color-Opponent Ganglion Cells • Look like concentric circles, which allows for further and richer color perception between different wavelengths. • More efficient discrimination of number of wavelengths • Enhanced information on color contrast in objects Form Perception: Perception of Edges • Sensory system enhances perception of borders o Mach band illusion • Lateral inhibition o Ganglion cells inhibit and are inhibited by neighboring cells o Stimulating photoreceptor #12 will excite it with green rays and inhibit #11 and #13 with red bands. o At edges, ganglion cells get differential amounts of inhibition darker edge and brighter edgeè makes edge stand out perceptually o Sensory system enhances perception of edges (Mach Illusion) • “On-center” and “Off-center” Ganglion cells o Antagonistic arrangement of receptive fields


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