notes for psy 220-psychobiology
notes for psy 220-psychobiology PSY 220
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This 14 page Class Notes was uploaded by KF Notetaker on Tuesday September 15, 2015. The Class Notes belongs to PSY 220 at University of Miami taught by Angela Szeto in Fall 2015. Since its upload, it has received 147 views. For similar materials see Psychobiology in Psychlogy at University of Miami.
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Date Created: 09/15/15
Psychobiology PSY 220 Biological psychology the study of the physiological evolutionary and developmental mechanisms of behavior and experiences Biological approach Why is there something instead of nothing Leibniz Why is there such thing as consciousness Chalmers Mindbrainbody problem relationship between mental experience and brain activity DualismDescartes mind and body are different types of substances mental and physical that exists independently Monism Materialism everything existing is physical Mentalism only the mind really exists and the physical world cant exist without some mind that is aware of it Biological explanation of behavior Physiological relates behavior to the activity of the brain need hormones to in uence brain activity neurons released to signal muscles to move the machinery of the body Ontogenetic describes the development of structure or a behavior looking at in uence of genes nutrition experience Evolutionary explanations looks at structure of behavior and how it relates in an evolutionary terms goosebumps shivering Functional describes why a structure or behavior evolved as it did Genetics and behavior Nature vs nature how both interact with each other to shape behavior what plays a role into psychological disorders sexual orientation Genes basic unit of heredity located in the nucleus Gregor Mendel Chromosomesstrands of gene pairs DNARNAprotein behavior deoxyribonucleic acids RNA ribonucleic acid that is used as a single stranded template for synthesis of proteins Proteins determine the development of the body by forming part of the structure or by serving as an enzyme or biological catalysts and regulate chemical reaction PTZ taste can either taste bitterness or not Autosomal genes nonsex linked genes every other genes Sex linked genes genes located on chromosome 23 X and Y XX and XY Y chromosome is small only has 27 proteins X has 1500 proteins Red green color blindness recessive gene on X chromosome men only have 1 so they are more likely to get it 8 women need it on both lt1 Sex limited genes present in both sexes usually on autosomal chromosomes but active in only one sex sex hormones activate them in one or the other testosterone activates chest hair in females its much lower 0 Gene Cha nge Mutati0n heritable change in a DNA molecule changing in one base pair can lead to a different protein Rarely advantages but FOXP2 gene language development sickle cell anemia Epigenetics changes in gene expression such as timing without modification of the DNA sequence Maternal deprivation cocaine exposure learning identicalmonozygotic twins shows that even though the genes don t change but the expression of them do Heritabilityan estimate of how much of the variance in some characteristic is due to heredity compare monozygotic twinsidentical dizygotic adopted children and biological parents Environmental in uences may affect traits with high heritabilityPKU genetically caused retardation that can be avoided through diet Evolution change over generations in the frequencies of various genes Arti cial selection breeding organisms for desirable individual characteristics wild mustard bred to create brussle sprouts cabbage cauli ower broccoli kale Misconceptions 0 Lamarckian evolution use or disuse of some structure causes an evolutionary increase or decrease 0 Humans no longer evolving because of medicine and prosperity 0 Evolution acts to benefit the individual Evolutionary psychology study of relationship between social behavior and evolutionary theory Altruistic behavior behaviors that benefit others rather than the individual committing the behavior Reciprocal altruism Kin selection Animals in research 4 reason why study animal behavior similar parts 1 Underlying mechanisms of behavior are similar across species and are often easier to study in nonhuman species 2 We are interested in animals for their own sake 3 What scientists learn about animals might shed light on our own evolution 4 Certain experiments cannot use human subjects because of ethical restrictions Lecture 2 Nerve cells and Nerve impulses Neurons nerve cells brain contains 100 billion neurons Santiago Ramon y Cajal through staining techniques revealed small gaps separating tips between neurons showed that they didn t grow into each other Showed brain made up of individual cell Camillo golgi developed a new method golgi stain that allows us to view neurons The nervous system is made of up 2 types of cells Neur0ns glia cells CELLs Composed of a lipid bilayer membrane that allows certain molecule Nucleus structure containing chromosomes Mitochondria powerhouse of cell needs fuel and oxygen Ribosomes protein synthesis ER network that transports protein 0 Rough ER has ribosomes that make and package proteins 0 Smooth ER make fats and steroids Neurons highly specialized cells that posses electrical impulses Motor neuron has a somacell body in the spinal cord and receives excitations and conducts impulses to a muscle in order to contract Sensory neuron receptor neuron that is sensitive to a particular type of stimulation Neuron dendrites cell body axon presynaptic terminal Small neurons can lack axons Dendrites branching tree like structure that have receptors that receive information from the neuron Dendritic spines short outgrowth that extends from dendrites Somacell body contains the nucleus and other basic structures found in most cells Axon a long thin fiber which sends the electrical impulse toward other neurons glands or muscles That is insulated by a myelin sheath Myelin sheath fatty insulating covering found on axons that allows the signal to travel further Nodes 0f ranvier gaps in the myelin sheath helps conducts the signal Presynaptic terminal swelling at the tip of the axon that releases chemicals that crosses between one neuron to the next such as neurotransmitters Afferent neuron refers to bringing information into a structure Efferent neuron carries away Interneuronsintrinsic neurons the dendrites and axons are contained within a structure Multiple sclerosis central nervous system disease myelin sheaths degrades that results in a loss of conduction velocity and means signals wont be sent through but only in the central nervous system Scars form where the sheath degraded causing the signal to be delayed or stopped loss of conduction velocity and energy efficiency results in impaired coordinated movement PNS Guillan Barre syndrome happens within the PNS is treatable immune system gets confused after a virus and it attacks the myelin Variations neurons have high plasticity vary in size shape and function but shae and function are closely related Glia cells other cells within brain but don t communicate to one another they are smaller and more numerous Surround and keep them in place supply oxygen and nutrients insulates neurons forms myelin 1 Astrocytes largest glia cells wraps around the presynaptic terminal and takes up chemicals released by the axon recycles causing cells to dilate removes debris and waste after neurons die cant regenerate 2 Microglia remove waste material as well as viruses fungi and other microorganisms Remove toxic substances after brain injury 3 Oligodendrocytes glia cells that build myelin in the brain and spinal cord found in CNS 4 Schwann cells build myelin in the peripheral nervous system 5 Radial glia guides the migration of neurons in the brain and the growth of axons and dendrites important for embryonic development After development they turn to neurons Blood Brain barrier keeps most chemicals out of the vertebrate brain needed because the brain lacks the type of immune system present in the rest of the body because neurons cant be replicated and replaced leads to minimal brain damage wall formed that keeps out viruses bacteria and harmful chemicals If a virus does make it through usually stays for life Endothelial cells form walls of the capillaries that are very tightly packed blocking most molecules from getting through Passively transportedno energy required 1 Smalluncharged molecules and 2 Molecules that can dissolve in the fats of the capillary wall vitamin A D drugs like weed and antidepressants Active transport system pumps necessary chemicals through such as amino acids vitamins and hormones and glucose Alzheimer s disease endothelial cells decrease and the brain blood vessels shrink and harmful chemicals can enter the brain also poses difficulty getting helpful medicines through Nourishment of neurons almost all neurons depend on glucosesimple sugar that can cross BBB B 1thiamine deficiency leads to an inability to use glucose which could lead to neuron death Chapter 2 Entire thing is electrically chargedpolarized Nerve impulse electrical message that is transmitted down the axon of a neuron Speed from 1100ms properties of the impulse are adapted to its the need Resting potential approximately 70mV Intercellular component is negatively charged Chloride ions extracellular uid is positively charged sodium ions creating an electrical gradient the membrane maintains an electrical polarization Resting potential the difference in electrical potential or voltage Protein channels sodium potassium calcium and chloride Ion channels ions selectivity along the concentration gradient Ion pumps require energy to pass through Movement of ions Diffusion Concentration gradient Electrical gradient the difference in charge between inside and outside of the cell More potassium inside the cells more sodium on the outside Electrical gradientthe positive potassium stays inside due to the strong negative charge within the cell During the resting potential the chloride is free to ow in and out through the channels potassium channels are mostly closed sodium channel also remain closed Sodium is attracted to the negative interior and the due to the concentration gradient but the channels remain closed Advantage of a resting potential allows the cells to react rapidly to stimuli Sodiuumpotasium pump active transport that requires ATP that transfers 3Na out 2K into the cell going against its concentration gradient Action Potential the messages sent by axons Depolarizati0n reduced polarization towards zero becoming more positive Hyperpolarizati0n becoming more negatively charged Requires a threshold of excitation for an action potential to occur needs enough stimulus to achieve the threshold Amplitude and velocity of an action potential is independent of the intensity of the stimulus Goes through a depolarization phases reaches a peak begins a repolarization phase followed by an undershoot where it becomes hyperpolarized and then returns back to the resting potential Depolarization sodium channels open hits the threshold and then closes at the peak Voltagegated channels regulating channels of sodium and potassium their permeability depends on the voltage differences across the membrane Potassium channels are slower open and to close it falls below the normal voltage and takes longer for it to return the NaK restores the concentration and electrical gradients Refractory period period immediately after the action potential when the neuron will resist the production of another action potential prevents it from going in the opposite direction Absolute refractory period Relative refractory period Axon hillock where the action potential begins swelling at the beginning of the axon Propagation of the action potential moves down the axon by regenerating Saltatory conduction jumping of the action potential from node to node faster this way and keeps it maintained Local neurons Small neurons with short dendrites and short axons don t follow all or none Graded potentials membrane potentials that vary in magnitude in proportion to the intensity of the stimulus get smaller as they travel Chapter 3 Synapse the specialized junctions that are central to all information processing in the brain Presynaptic neuron sends the message Postsynaptic neuron receives the message Ramon y Cajal Charles Scott Sherrington discovered properties of the synapse from his experiments on re exes in dogs Afferent sensory Efferent motor 1 Re exes are slower than the conduction along an axon 2 Several weak stimuli presented at slightly different times or locations produce a stronger re ex than single stimulus 3 Exciting one set of muscles leads to a relaxation of others Re ex arc the circuit from sensory neuron to muscle response Sherrington 1st nding moved at a rate of 15ms he believed the difference in the speed of conduction of the re ex arc vs that of an action potential must be accounted for by the time it took for communication between neurons 2nd nding a light pinch didn t do enough to cause a re ex the synaptic transmission was too weak to reach the threshold Temporal summation repeated stimuli to a cell can have a cumulative effect when a single stimuli is too weak single neuron Spatial summation synaptic input from several locations different neurons can have a cumulative effect and trigger a nerve impulse Graded potentials either depolarizationexcitatory or hyperpolarizationinhibitory of the postsynaptic neuron Action potential transmitted at the axon hillock depolarization selfpropagating same amplitude and follows the all or none principle Graded potential produced by dendrite stimulation that travels short distances to hillock can have small ips that are either inhibitory or excitatory decays over time the amplitude depends on the stimulus and depends if its temporal or spatial summation EPSP s excitatory postsynaptic potential graded potential that decays over time and space partial depolarization caused by sodium ions entering the postsynaptic neuron transmission at single synapses doesn t open enough gates to reach action potential threshold therefore need cumulative effect and are the basis for temporal and spatial summation IPSP s inhibitory postsynaptic potential temporary hyperpolarization of a membrane when the potassium ions leave the cell and chloride ions enter the cell It serves as an active brake that suppresses excitation Probability of an action potential on a given neuron depends on the ratio of EPSlePSP more synapses that a response travels through the longer it will take Sherrington assumed that synapses produce on and off responses the effect of 2 synapses could have more or less than a doubling effect Spontaneous ring rate periodic production of action potentials despite synaptic input EPSP increase number of action potentials above spontaneous firing rate and IPSPS decrease it below TR Ellott sympathetic nerves stimulate muscles by releasing adrenaline or a similar chemical but didn t have enough evidence Otto Loewi that signals must be sent chemically Neurotransmitters chemicals that travel across the synapse and allow communication between neurons calcium needs to enter the end terminus of the axon for the release of neurotransmitters Synaptic cleft space between pre and postsynaptic neurons The major sequences of events that allow communication between neurons across the synapse are as follows The presynaptic neuron synthesizes chemicals that serve as neurotransmitters Action potentials travel down the axon Released molecules diffuse across the cleft attach to receptors and alter the activity of the postsynaptic neuron The neurotransmitters separate from the receptors 5 The neurotransmitters are taken back into the synaptic neuron diffuse away or are inactivated by chemicals 6 The postsynaptic cell may send negative feedback to slow the release of further neurotransmitters Types of neurotransmitters 1 Amino acids contain amine groups glutamate GABA glycine 2 Neuropeptides chains of amino acids long chains of polypetodes endorphins 3 Acetlychlorine released during a re ex its an amino acid with the NH2 replaced by NCH33 4 Monoamine neurotransmitters containing an Nh2 group formed by metabolic change of an amino acid serotonin dopamine epi 5 Purines adenosine and several of its derivatives ATP 6 Gases nitric oxide Neurons synthesize neurotransmitters from precursors derived originally from food Catecholaminedopamine epi norepi three closely related compounds containing catechol and an amine group Smaller neurotransmitters are synthesized in the presynaptic terminal and held there for release Larger neurotransmitters are synthesized in the cell body and transported down the axon can take hours or days and are slow to replenish Vesicles tiny spherical packets located in the presynaptic terminal where high concentration of neurotransmitters are held nitric oxide is an exception MAOmonoamine oxidase breaks down the transmitters into inactive chemicals Exocytosis refers to the excretion of the neurotransmitter from the presynaptic terminal into the cleft Most individual neurons release at least 2 or more different kinds of neurotransmitters Some release from different branches of its axons acetylcholine to muscles and acetylcholine and glutamate to the spinal cord Depression chemicals are released and the dopamine is sucked back up antidepressants plug up the vacuum Chapter 3 part 2 Sequence of chemical events at synapse Synthesis of neurotransmitters They are transported to vesicles Releases into the postsynaptic cleft They are then reuptaken Amino acids Monoamines Catecholamines dopamine norepinephrine and epinephrine and Inolamines serotonin Acetylcholine released at neuromuscular junction Neuropeptides Purines Gases AT the postsynaptic membrane Iontropic effect neurotransmitter binds to receptor site and immediately opens an ion channel act fast and are very short lasted Transmittergated ligand gated channels Glutamate most abundant excitatory transmitter and GABA which is inhibitory limitedlocailized to one point of the membrane Metabotropic effects neurotransmiiters attach to a recptor and initiate a sequence of slower and longer lasting metabolic reactions slower and longer lasting dopamine NE serotonin sometimes glutamate and GABA Neurotransmitter attaches to a metabotropic receptor that bends the receptor protein that releases gprotein In uences activity in a larger area of the cell Gprotein an energy storing molecule increase the concentration of a second messenger Second messenger communicates to areas within the cell Agonists drugs that act like a neurotransmitter Neuromodulators metabotropic effects that utilize a number of different neurotransmitters can increase or decrease of neurotransmitters released but doesn t directly act on it Neuropeptides formed in cell body released from the dendrites Hormones chemicals secreted by a gland and transported through the blood Where it alters activity Endocrine glands in the brain the most responsible are the hypothalamus and pituitary glands Pituitary gland attached to the hypothalamus Anteri0r composed of glandular tissue GH ACTH TSH FSH LH and prolactin FLAGTOP P0steri0r composed of neural tissue extension of hypothalamus that releases oxytocin and vasopressin regulated ADH released in bloodstream but is metabolized very quickly and stimulates Reuptake taken up by the presynaptic neuron to be reused or broken down by MAO Transporters special membrane proteins that facilitate reuptake normally on presynaptic neuron Agonist drug that mimics or increases the effects of neurotransmitters Antagonist drugs that block the effects of neurotransmitters affinity of a drug how strong or weak depending on how it binds efficacy of the drug its tendency to activate the receptor Nucleus accumben reward center of the brain that releases dopamine Distinction between liking and wanting behaviors different areas within the nucleus accumbens Stimulant drugs increase excitement alertness motor activity and elevated mood have shortlived effects Nicotine affects the acetylcholine receptors nicotine receptors increases dopamine release Opiates morphine stimulate endorphin synapses that inhibit the release of dopamine Marijuana cannabinoids and THC Hallucinogenic drugs increase body temperature and neurotransmitter damage Alcohol has a potential benefit in moderation Type I type A later in life with a gradual onset menwomen Type 11 type B greater genetic component has a rapid and earlier onset men outnumber women
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