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Chapter 3 The Biological Bases of Behavior.pdf

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PSYC 2510
Agnieszka Kopinska

Chapter 3: The Biological Bases of Behavior Monday, October 03, 201112:07 PM Nervous Tissue - Myelin Sheath-- Insulating material that speeds up the transmission of signals - Glial Cells-- Provide structural support for neurons ○ Account for over 50% of brain's volume ○ Nourish neurons, help remove waste in neurons, and contribute to myelin formation ○ New research suggests they play a much more important role than once thought Neural Impulses - Neural impulses are the electrochemical messages relayed from one neuron to another - Involve the concentration of positively (Na+ and K+) and other negatively charged (Cl-) ions on oither side of the cell membrane - Resting potential-- when the neuron is inactive, negatively charged - Action potential-- neuron briefly shifts to a less negative or even positive charge ○ All-or-none law - The refractory period follows an action potential - Synapse-- junction where information is passed between neurons - Neurotransmitters ○ Stored in the terminal button ○ Often released by an action potential ○ Binds to specific receptors on postsynaptic neuron membrane - Postsynaptic Potential (PSP)-- the voltage change at the receptor site of a postsynaptic neuron upon receiving a neural impulse - Does not follow the all-or-none law: ○ Excitatory PSP ○ Inhibitory PSP - Neurotransmitters' fate: ○ Diffusion ○ Enzyme deactivation ○ Glial cells ○ Reuptake into the presynaptic neuron Neural Networks - Many neurons must be firing and communicating to effect an action - Across development, neural networks get organized and more refined ○ Pruning-- "Use it or lose it" Neurotransmitters - Chemical messengers - Play important role in physiological and psychological functioning - Lock and key system with receptors ○ Agonist-- chemical that mimics a neurotransmitter and binds to its receptors ○ Antagonist-- chemical that counteracts the effect of a neurotransmitter by blocking its access to receptor - Acetylcholine ○ Acts between motor neurons and voluntary muscles to allow movement (e.g., walking) ○ Contributes to attention, alertness, memory, and REM sleep Too much: convulsions, muscle paralysis, death Unit 1 Page 1 ○ Too much: convulsions, muscle paralysis, death ○ Too little: Alzheimer's (memory deficits) ○ Nicotine is an agonist - Monoamines ○ Regulate many aspects of daily life ○ Linked to many psychological disorders ○ E.g., dopamine, serotonin, norepinephrine - Dopamine ○ Regulates voluntary movements (e.g., walking) ○ Involved in learning, attention, emotion, and thought ○ Too much: links to schizophrenia ○ Too little: Parkinson's disease - Serotonin ○ Involved in regulation of mood, sleep, impulsivity, aggression, and appetite ○ Deficits may result in suicide and increased aggressive behavior - Norepinephrine ○ Involved with sleep, eating, and mood ○ Too little of both is linked to depression ○ SSRIs-- antidepressant medication - Amino acids ○ GABA-- produced inhibitory postsynaptic potentials of anxiety ○ Glutamate-- produces excitatory postsynaptic potentials  Learning  Memory - Endorphins ○ Natural pain killers, similar to opiates (e.g., opium, morphine, heroin) ○ Contribute to response to stress  Provide relief from pain  Produce feelings of pleasure - There are many other kinds of neurotransmitters in our nervous system The Nervous System - The peripheral nervous system (PNS) ○ The nerves other than those found in the central nervous system (CNS) ○ Nerves-- bundles of axons that run through the body ○ Subdivided into the somatic and autonomic nervous systems  Somatic nervous system □ Carries sensory and motor information to and from the CNS □ Allows for voluntary movements □ Afferent nerves-- carry info to the CNS □ Efferent nerves-- carry info from the CNS  Autonomic nervous system □ Regulates involuntary bodily processes (e.g., breathing, digestion, heart rate) □ Sympathetic system-- regulates the flight-or-flight response □ Parasympathetic system-- conserves physical resources - The central nervous system (CNS) ○ Consists of the brain and the spinal cord ○ Meninges protect the CNS ○ Cerebrospinal fluid (CSF) also protects the CNS from injury and nourishes the brain  Functions of the CSF: Unit 1 Page 2  Functions of the CSF: □ Buoyancy and circulation □ Protection from injury □ Chemical instability-- rinses metabolic waste from CNS to maintain pH □ Reduced intracranial pressure ○ Spinal cord  Bundles of axons transmit neural impulses from brain to peripheral nerves and vice-versa  Plays important role in communication between motor neurons and the brain ○ The brain  Weighs approximately 1.5kg  Is made up of billions of neurons  Is the executive coordinator of the nervous system Brain Research Approaches - Historically, the brain could only be examined through autopsies - Technological advances allowed for the study of the live brain ○ Mapping of brain function as opposed to only structure - Electrical Recordings ○ Broad patterns of brain electrical activity are recorded using an electroencephalograph (EEG) ○ Electric potentials in the brain cells are added up and amplified ○ Output is brain waves  Non-invasive  Ideal for use with children  Good measure of brain-behavior relationships  Helpful to measure changes in patterns of activity across development - Lesioning ○ The controlled, intentional destruction of a part of the brain ○ Done with animals in humane conditions (e.g., anesthetics) ○ Purpose is to study the relationship between brain and behavior more directly ○ Performed with a stereotaxic instrument - Electrical Stimulation of the Brain (ESB) ○ Stimulating a part of the brain using a weak electrical signal (not as strong as in lesioning) ○ Used mainly with animals ○ Can be used with humans in the context of brain surgery ○ Has been used in research on learning, seizures, and pain reduction, among others - Transcranial Magnetic Stimulation (TMS) ○ Temporarily alters brain activity in a specific brain area ○ Creates virtual lesions in small, specific, surface areas of the brain ○ Used to evaluate damage from strokes, MS, and spinal cord injuries ○ Non-invasive ○ Cannot be used to stimulate deep structures of the brain - Brain Imaging Techn
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