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PSYC 372- Chapters 4 & 5

by: Aimee Castillon

PSYC 372- Chapters 4 & 5 PSYC 372

Marketplace > George Mason University > Psychlogy > PSYC 372 > PSYC 372 Chapters 4 5
Aimee Castillon
GPA 3.61
Physiological Psychology
Jennifer Sontag

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Physiological Psychology
Jennifer Sontag
Class Notes
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This 15 page Class Notes was uploaded by Aimee Castillon on Monday September 7, 2015. The Class Notes belongs to PSYC 372 at George Mason University taught by Jennifer Sontag in Summer 2015. Since its upload, it has received 57 views. For similar materials see Physiological Psychology in Psychlogy at George Mason University.


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Date Created: 09/07/15
52515 Chapter 4 Resting Membrane Potential how do neurons communicate Individual neurons are activated by transmission of electrical signals Neurons communicate with one another using chemical signals Must understand the electrical and chemical properties of the cell membrane in order to understand neuron communication neuron cell membrane Separates inside of neurons from the outside environment extracellular fluid Recall that is composed of a bilipid layer with proteins embedded in it neuron membrane is selectively permeable Most chemicals cannot cross freely Flow controlled by specific protein channels embedded in the cell membrane Opening and closing of these channels often depends on the electrical charge of the inside vs the outside of a neuron membrane potential Neurons function similarly to batteries There is a difference in voltage electrical charge between the interior and exterior of the cell This difference is called the membrane potential recording membrane potential Scientists first used the axon of a giant squid Microelectrodes extremely fine electrodes used for intracellular recording Isolated an axon and placed it in saltwater Placed 1 electrode inside the axon and 1 in the saltwater Measured the difference in charge between the inside amp outside of the axon resting potential The value of the membrane potential in a neuron that is at rest not sending a signal The resting potential of a neuron is usually around 70 millivolts mV forces contributing to resting potential Distribution of ions inside and outside of the cell membrane Sodiumpotassium pumps Also contribute to the uneven distribution of ions at rest Protein complexes embedded in the cell membrane different from ion channels Active transport mechanisms that use ATP for energy Transports 3 sodium Na ions out of the cell for every 2 potassium K ions it draws in neuron polarization When it is at rest the inside of the neuron is negatively charged relative to the extracellular fluid the membrane is polarized ions Charged particles that make up the salts in neural tissue 2 basic types anions all negatively charged ions cations all positively charged ions important types of ions Sodium Na Potassium K Chloride C Calcium Ca Organic anions negatively charged distribution of ions lons are unevenly distributed within the inside vs outside of the neuron cell membrane when it is at rest More Na Cl Ca ions outside the cell More K ions inside the cell Organic anions stuck inside the cell too large ion channels lons can only move across the membrane through ion channels embedded in the cell membrane Selective for1 type of ion Exception organic anions Are stuck and cannot move to the outside the cell Channels are voltagegated Openclose depending on the value of the membrane potential mostly closed at rest Action Potentials Electrical impulses triggered when neurons are stimulated Occurs due to ions moving through voltagegated channels in the cell membrane steps of action potential resting refer to previous lecture Depolarizing phase A threshold of excitation is reached at the cell membrane Voltagegated Na ion channels open Na ions rush into cell Membrane potential rapidly becomes less negative Depolarization reduction in negative charge Peak of the action potential The action potential quickly reaches its peak Na ion ch anne become inactivated more Na ions can enter e neuron Repolarizing phase K ion channels openquot K ions flow out off the neuron Cell membrane begins to repzolarize return towards resting potential value Hyperpolarizzing phase u nd ershoot Kj channels stay open K ions continue to leave cell Causes cell membrane to quotundershoot the resting potential Hyperpolari z ation increase in negative charge relative to resting potential value K channels stay open K ions continue to leave cell return to resting state ion channels close Causes the membrane potential to return toward resting value NaK pumps help to eventually restore the resting otentiial refractory periods Absolute refractory period ms after an action potential has been fired it is impossible to trigger another one Relative refractory period for a few more an action potential can only be fired by applying higher than normal amounts of stimulation allor none law Onoe an action potential is triggered the impulse travels the length of an axon without decreasing in strength conduction of action potentials in myelinated axons Na ion channels are highly concentrated at the nodes of Ranvier Action potentials fjum from node to node saltatory conduction The myelin sheath thUS speeds up the conduction of action potentials Multiple sclerosis autoimmune disease that results in destruction of the myelin sheaths of neurons Results in slower transmission of action potentials Postsynaptic Potentials pre vs postsynaptic potentials When a neuron fires an action potential a chemical signal released from its terminal buttons Signal diffuses across the ssynia pse Point of communication between 2 neurons The proSynaptic neuron releases the signal and the postsynaptic neuron receives it postsynaptio potentials The chemical Sig n39a l binds to receptors on the postsynaptie neurons cell membrane Signal can have 1 t effects on the postsynaptic membrane Depolarization increase membrane potential Hyperpolarization decrease membrane potential EPSP and IPSPs Depolarizations are excitatory postsynaptic potentials EPSPs Increase the likelihood that the postsynaptic neuron will fire an action potential Hyperpolarizations are inhibitory postsynaptic potentials lPSPs Decrease the likelihood that the postsynaptic neuron will fire an action potential summation Both EPSPs and IPSPs are graded responses Weak signals elicit weak PSPs Strong signals elicit strong PSPs Multiple PSPs are integrated and summed together to produce an overall effect on a postsynaptic neuron integration of postsynaptic potentials Spatial summation PSPs produced simultaneously on different parts of the postsynaptic neuron Temporal summation PSPs produced in rapid succession at the same part of the postsynaptic neuron The Synapse and Neurotransmitters synapse Tiny gap between neurons across which a chemical signal is communicated types Axodendritic terminal buttons of presynaptic neuron synapse onto dendrites of postsynaptic neuron Axosomatic terminal buttons onto cell body Axoaxonic terminal buttons onto axon anatomy of a synapse Presynaptic membrane cell membrane at the ends of the terminal buttons Site from which chemical signals called neurotransmitters are released into the synapse Neurotransmitter molecules are stored in synaptic vesicles until release Postsynaptic membrane cell membrane of the neuron receiving the signal Contain receptors Binding sites for signals released from the presynaptic cell neurotransmitters The chemical signals released across the synapse are neurotransmitters Several classes Amino acids the building blocks of proteins Excitatory glutamate aspartate Inhibitory GABA glycine Monoamines Synthesized from a single amino acid Catetcholamines quotOpamine Norepifneph rine Epinephrine Indolemines Serotonin Acetylcholine Choline molecule with an acetyl rou p added dessp read in the and at neuromusc uliair junctions Neuropeptides Long of amino acids Pituitary pe ptides oxytocin Hypothalamic pe tides egg corticotropinreleasing hormone RH Braingut peptides oholecyy stokinin peptides eg substance P miscellaneous 39 Unconventional neurotransmitters Synaptic Transmissions Action potentials arrive at the terminal buttns f a neuron and trigger release f neurotransmitter molecules into synapses 4 major events Neurotransmitter and storage Ne urotransmitters are synthesized in the cytoplasm ofthe cell body or terminal buttons and packaged into vesicles Vesicles are stored in clusters next to the membrane A neuron can synthesize and release more thani kind of neurotransmitter eexistence ie GAB A and neuropetiides Neurotransmitter release Exocyt05 i5 39 the process of release of neurotransmitter molecules from synaptic vesicles and into the eynatic cleft An action potential is transmitted down the of the presynaptic neuron and reaches the terminal buttons Depolarization causes voltagegated calcium Ca2 ion channels to open on the presynaptio membrane Sta2 ions enter the presynaptio membrane Synapticvesicles fuse with the presynaptic membrane and empty their contents into the synaptic Cleft Activation of na ptic receptOrs Released neurotra nsmitter m39ioesculzes attach to receptors on the postSyn a ptic membrane Usually on the dendrites Ligand any molecule that binds to a receptor Neurotransmitters are thus ligands Each receptor co ntiainis binding sites for particular of neurotra nfsmitters neurotransmitter can only influence cells that have receptors for it receptor subtypes neurotransmitters can bind to more than one receptor subtype dopamine Receptor typically trigger different types of responses in the postsygnaptio neuron dopamine binds to D1 gt excitatory effect dopamine binds to D2 gt inhibitory effect Neurotransm itter inactivation and reuptake 39 Neurotransmitter signals must be terminated after release and binding to postsyna pti receptors ReUptake T39ra po rters proteins in the cell mem brane th at neurotransmitter molecules back into the presynaptic neuron tor repgaskagji ngre use eg serotonin 5HT is taken back serotonin trans porters EyTs to treat deiressiion degradation Enzymes break neurotransmitter molecules down into inactive emficaIs that eventually wash away e aicetyloholiinesterase ACh E brea down ACh Effects of Drugs at the Synapse Ligands are any molecules that bind to receptors including neurotransmitters Drugs are also ligands agonist antagonists Agonist a drug that mimics or facilitates the actions of a neurotransmitter 9th nicotine is an agonist at ACh receptors Antagonist a drug that inhibits the actions of a neurotransmitter eig many antipsychotic drugs are dOpamin e 52815 Chapter 5 52815 Imaging and Stimulating the Human Brain Structural imaging Computerized tomography CT scanning A contrast Xray technique Brain tissue does not show up well on a traditional Xray Inject a substance eg iodine that absorbs Xrays to enhance contrast and allow visualization of brain tissue Developed in the early 1970s Magnetic resonance imaging MRI ie headaches A general technique that can be used to determine the amount of certain types of atoms in different locations in the body In biopsychology used to measure to the hydrogen atoms within the water and fat of the brain The hydrogen atoms are activated by highfrequency magnetic waves Alignment of the atoms generates a detailed structural image Can be used to generate a series of 2D or 3D images advantages of MRI over CT No exposure to radioactivity is required Images generated have better resolution Functional imaging Positron emission tomography PET First functional imaging technique Basic procedure Inject radioactive 2deoxyglucose 2DG into the patient s carotid artery Mimics glucose the brain s primary fuel Accumulates in neuronsglia instead of being metabolized Levels of 2 DG reflect amount of activity within a brain area PET scans are 2D maps of radioactivity rather than detailed images of the brain Functional MRI More active brain areas take up more oxygenated blood than less active ones Oxygenated blood has magnetic properties fMRI records the bloodoxygenIeveIdependent BOLD signal generated by active brain areas advantage over PET scans No injections of radioactive substances Both structural and functional information provided Better spatial resolution Produces 3D images BOLD signals must be interpreted with caution The relationship between BOLD signals and actual neural activity is still not clear fMRI has poor temporal resolution Images take 23 seconds to create Transcranial Magnetic Stimulation Only method for noninvasively stimulating the brain Used to affect activity within the cerebral cortex The procedure A large coil is positioned next to the skull Coil creates a magnetic field Briefmild application stimulates an area Prolongedintense application inactivates an area Observe behavior before and after application Psychophysiological Recordings in Humans most common psychophysiological techniques Scalp electroencephalography EEG Measures electrical activity of the brain Action potentials Postsynaptic potentials Electrical signals from the skin muscles blood and eyes Can only record signals from the cerebral cortex Closest to the scalp The procedure Attach electrodes to the scalp Directly or using an electrode cap Record average activity for a population of neurons located under the electrodes spontaneous activity or eventrelated potentials in response to a stimulus Squiggles on the EEG output are electroencephalograms Some waveforms correlate with particular states of consciousness or pathologies eg epileptic seizures Traditional EEG has high temporal resolution but poor spatial resolution Newer techniques allow the EEG signals to be represented on a 3D MRI image to improve localization Electromyography EMG Records muscle tension Contractions of individual fibers that make up skeletal muscle Procedure Tape 2 electrodes to the skin over the muscle of interest Raw signal reflects number of muscle fibers contracting at any given time Integrated signal is a simpler measure of muscle tension Electrooculography EOG Records changes in electrical charge generated when the eyes move Electrodes placed either above and below the eye vertical movements or to the right and left of the eye horizontal movements The skin conductance response SCR measures transient changes in skin conductance associated with specific eventsexperiences Emotional thoughts and experiences are associated with increased skin conductance Ability of the skin to conduct electricity Most likely due to sweat gland activity Sensors placed on area of skin that contains a high concentration of sweat glands eg fingers Part of the measurements taken during a polygraph Cardiovascular activity Cardiovascular system blood vessels and heart Activity can change with the experience of emotions Most commonly used measures Blood pressure Blood volume Heart rate Heart rate is measured using an electrocardiogram ECG Measures the electrical activity of the heart using electrodes placed on the chest Can compare heart rate before and after presentation of an emotional stimulus Neuropsychological Testing Methods in Humans purpose of neuropsychological testing Used to assess perceptual emotional motivational or cognitive functions Most often done in patients with brain damage Assists with diagnosis Basis for treatment program Evaluate effectiveness of treatments approach Pre1950s Singletest approach 1950s1960s Standardizedtestbattery approach Problem one size fits all tests are not adequate is effective 1960spresent Customized testbattery approach Objective characterize the psychological deficits of each patient Basic procedure Common battery of tests Psychological abilities tested Intelligence Weschler Adult Intelligence Scale WAIS Used to determine the patient s IQ 11 subtests including basic memory tests Language The token test 20 tokens of different shapes and colors Directions proceed from simple touch a green square to complex touch the large green square then the small white circle Language lateralization Lateralization unequal division of function between the hemispheres ie one hemisphere is dominant 2 tests of language lateralization Dichotic listening test Noninvasive test Pairs of spoken digits or syllables presented through earphones Different digitssyllables presented to each ear simultaneously Ask patient to report all of the digitssyllables they heard Will report slightly of the digitssyllables presented to the ear contralateral to the hemisphere dominant for language Sodium amytal Wada test Invasive given to patients prior to neurosurgery Anesthetize one hemisphere at a time via injection of sodium amytal into the carotid artery Give the patient a series of simple tests Counting Naming objects Speaking and understanding language More impairments will be seen when the languagedominant hemisphere is anesthetized Tests of specific neuropsychological functions There are thousands of specific tests Generally used to test Memory Types of memory impairments See Chap 11 Shortterm vs longterm Retrograde forget things learned earlier or anterograde inability to learn new things Explicit consciously recalled memories or implicit memories demonstrated by performance Patients with amnesia are often impaired on tests of explicit memory while performing well on implicit memory tests Language Possible types of language deficits Problems of phonology sounds Problems of syntax grammar Problems of semantics meaning ie Broca s aphasia testing Frontal lobe function The Wisconsin Card Sorting Test Each card contains 14 symbols of a certain color Patient must sort by color number or symbol doesn t know the rules Not told which way to sort but is told when an error is made Once ten correct card placements are made the task switches sorting method Perseveration failure to switch to the new sorting rule Invasive Methods in Animals stereotaxic surgery Procedure to position experimental devices in the depths of the brain Electrodes Small knife blades Cryoprobes Basic procedure A stereotaxic atlas is used to locate the brain structure of interest Animal is anesthetized and placed into the stereotaxic instrument A hole is drilled through the skull at desired position and device lowered into the hole Types of invasive methods Electrical stimulation methods Weak electrical current passed through an electrode Causes increased firing of neurons near the electrode Used to gain information about the function of a brain structure Stimulation can elicit behavioral sequences in animals Eating Drinking Aggressionattack Copulation Sleeping Invasive recording methods 4 types Intracellular unit recording position a microelectrode inside a neuron s cell membrane Must anesthetize or immobilize the animal Extracellular unit recording microelectrode positioned in the extracellular fluid Can record signals from up to 100 neurons using several different electrodes Multipleunit recording electrode picks up signals from many neurons Invasive EEG recording large electrodes pick up general electrical activity with a brain area Lesion methods All require stereotaxic surgery to be performed first Lesion removal damage or destruction of part of the brain Observe behavior before and after lesion or in lesioned vs nonlesioned control group 4 types of lesions Aspiration a finetipped glass pipette is used to suction out an area of cerebral cortex tissue ie frontal cortex doesn t require stereotaxic surgery Radiofrequency Highfrequency current passed through an electrode heat from current destroys neurons Knife cuts small blade is swung back and forth to make the cut Cryogenic blockade coolant pumped through a cryoprobe causes neurons to stop firing Reversible neurons start firing again once warmed back UIO Can be unilateral or bilateral interpreting lesion effects Lesions rarely leave adjacent brain tissue unaffected Effects of lesion may be due to damage to adjacent tissue not the tissue targeted Genetic techniques Genetic knockouts Genetic knockins Transgenic animals Primarily mice Knockoutknockin mice Delete or overexpress a gene of interest eg mice lacking leptin gene are obese Transgenic mice Insert a human gene into the animal s genome eg mice with the human APP gene gt Alzheimer s Biopsychological Paradigms of Animal Behavior types of paradigms Assessment of speciescommon behaviors Speciescommon behaviors those displayed by nearly all members of a species Grooming Eating Drinking Copulating Fighting Openfield test Place the rat in a large empty chamber Record activity General locomotor activity distance traveled Rearing Time in center Thigmotaxis time near the walls Tests of aggressive and defensive behavior Colonyintruder paradigm ofquot male rats frm social hierarchies Introduce a smaller quot in truder rat into the cage fa dominant rat and observe behavior Aggression dominant rat piloerection lateral approach flank and backbiting Defensiveness intruder rat freezing boxing rolling over Elevatedpslusm39aze A test of defensive behavior The maze 4 arms arranged in a shape 50 mm above the floor 2 closed arms with side Walls secure 2 open arms with no sidewalls vulnerable Place rat on the maze and measure time spent on open arms vs Closed arms Traditional conditioning paradigms Pavlovian acondii tiioning Initially neutral stimulus conditioned sifti mulustg paired with an unconditioned stimulus US that elicits an unconditioned response R After enough pairings presentation ofthe atone elicits a conditioned res ponse pae rant conditioning Rat performs a response that is followed by a articular consequence Reinforcement u nit sh me not Examples Press a lever gt food pellet presented reinforce ment39i Turn a Wheel gt shock administered punishment selfstimutatiion Seminatural animal learning paradigms Condition ed taste aversion An avoidance response developed to the taste of a food when consumption was previously followed by illness Basic pr39pcedu re Give rat a novel food Administer an emetic nauseaind ucing drug Rats learn to avoid the food after only a single pairing with the emetic rug Radial arm maze A test Ff spatial navigation Array of arms radiating frm a center area Some arms Sontain food Other arms not Rat learn t remember which arms have fed based on external cues in room 39 Morris water maze Another spatial navigation test Rat is placed in a circular p00 of milky wath Platform located 2 cm under SU rface ofer ivfisual cues on walls around pool Several training trials per for several days Rat must leiam to use external cues to find the platform


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