Class Notes (809,569)
United States (313,690)
Psychology (312)
PSY 101 (146)

Biological Foundations of Behavior.docx

19 Pages
Unlock Document

University at Buffalo
PSY 101
Professor Berg

Biological Foundations of Behavior Thursday, February 6, 2014 12:51 PM Heredity and Behavior • Distinguish forces in nature (heredity) vs. nurture (environment) • Researchers face different challenges observing environmental vs. biological forces that shape behavior • How and which behaviors are passed from generation? Evolution and Natural Selection • Charles Darwin o Took 5-yr survey of South American coast o Wrote On the Origin of Species • Offspring tended to be highly similar to birth places • Suggested an explanation- called it natural selection- for variety of species observed during survey • Proposed a mechanism to support the theory of evolution o Adaptiveness to environment constrains set of species that are successful in reproduction o Theory of evolution by process of natural selection • Members from each species emerge from a common set of ancestors • Organisms surviving to reproduce will see their traits become more numerous in the population • Considered the course of evolution as survival of the fittest… • Survival of the fittest o Species?...species member? Both! o Those that possess the psycho-physiological attributes best adapt to environment are likely to survive; they have a selective advantage o How should "success" be defined in evolutionary terms? o How should we go about predicting which species will exist in the future? • 2 major adaptations in human evolution: o Bipedalism (ability to walk upright); emerged about 6million years ago o Encephalization (increased brain size); our brain (Homo sapiens) roughly 3X size of early ancestor (Australopithecus africanus) • Intelligent bipeds afforded the opportunity to reproduce) • Genotype o Individually inherited from genetic structure of birth parents o Thousands of these make up the threadlike chromosomes present in a cell o Responsible for production of proteins that regulate expression of traits • Phenotype o Observable characteristics of interaction between genotype and environment (e.g. hair color) o Individual expression of traits (some influenced by more than one gene) o Large (almost infinite) # of possible combinations Variation in the Human Genotype • Genetics o Study of heredity and reproduction o DNA (deoxyribonucleic acid) is found in the nucleus of each of you cells; composed of genes that act as the biological unit of heredity o Chromosomes (46 total, 23 from each parent) are composed of thousands of genes; unique combination •One chromosome from each parent is devoted to carrying the genetic code for development of male or female characteristics •Sex chromosomes are inherited as: o One X chromosome from you mom and one X or one Y chromosome from you dad o Outcome XX= female, XY= male •For many gene types there are different forms known as alleles •Phenotype determined by inherited versions • Presence of dominant and/or recessive alleles determine trait expression •Full set of gene expressions constitutes the genome of an organism •Some easily observable examples of 2 phenotypic versions present in human population: o Bent pinky- dominant version of gene causes distal segment of pinky finger to bend distinctly inward toward ring finger •Researchers interested in learning about the relationship between inheritance and behavior study human behavior genetics o Search for casual links as they evaluate genetic components of behavior and traits o Measure heritability, the relative extent to which patterns of behavior are influenced by genetics vs. environment •Measure heritability •In order to investigate heritability, researchers employ a couple of different methods: o Adoption studies o Twin studies •Adoption studies: o Aim to compare the similarity between behavior and traits of adopted child with that of birth parents vs. adoptive family • Similarity between adopted child and birth parents- genetic influence • Similarity between adopted child and adoptive parents- environmental influence •Twin studies: o Compare similarity of behavior between monozygotic twins (MZ, identical twins) and dizygotic twins (DZ, fraternal twins) o MZ's share 100% identical genetic material; DZ's share 50% of same genes o MZ's and DZ's share similar environment The Neuron •Cells that perform specialized functions to receive, process, and transmit info. With other intrabody cells are called neurons •Neurons may differ in functionality, size, and shape, but all have same structural components •100billion neurons in a human brain •General function: Receive nerve impulses on one end (dendrites), release communicators to stimulate other neurons at opposite end (terminal buttons) •Dendrites pass info to soma (containing nucleus and cytoplasm) where signals integrate •The soma transmits integrated into along a neural fiber- the axon- that allows nerve impulses to pass •The axon passes nerve impulses toward the opposite end (away from dendrites); terminal buttons allow stimulation of nearby glands, muscles, and other neurons • • 3 major classes of neurons: o Sensory neurons • Carry nerve impulses away from sense receptors toward the nervous system o Motor neurons • Carry nerve impulses away from the nervous system toward muscles and glands o Interneurons • Relay nerve impulses between neurons (mostly found in the central nervous system) • Glial cells o Surround neurons to hold them in place o Facilitate transmission of nerve impulses o Manage removal of corrupted neurons o Protect brain from foreign substances (blood-brain barrier) o Produce insulating cover for some axons called a myelin sheath • Figure: Pain withdrawal reflex • Brain receives info AFTER finger has already been moved away from pin Action Potentials • Nerve impulses transmit info by means of electrochemical signals • Signals may be excitatory or inhibitory input to the receiving neuron • Excitatory input increases the likelihood of an action potential (release of electrochemical signals due to neuron activation), while inhibitory input decreases likelihood that neuron fires • Resting potential o In a resting state o Capable of producing an action potential • If a neuron receives enough excitatory input to reach threshold, then the neuron will fire • Threshold met = action potential • Threshold not met = no action potential • Action potentials are all-or-none; an action potential either occurs or it does not o No partial action potentials o No difference in magnitude; they are uniform (i.e. like a set of firecrackers) • Shown: Membrane potential over time • After an action potential has passed through a segment of the axon, that segment enters a refractory period (2 parts) o Absolute- no other action potential may pass o Relative- an action potential may pass, but needs enough activation to first get back to baseline Synaptic Transmission •Neurons do not touch at site of transmission; they communicate across a gap call the synapse •Occurrence of action potential ignites firing of neuron; when a neuron fires and communicates across the synapse (with another neuron) it is said to have accomplished synaptic transmission •Synaptic transmission has been initiated when neurotransmitters (neuron stimulators) are moved toward a terminal button •Neurotransmitters are carried by synaptic vesicles that attach to the presynaptic membrane of the firing neuron •Synaptic transmission occurs when neurotransmitters attach to receptor molecules in the postsynaptic membrane of the receiving neuron •Neurotransmitters will bind if… o …there is not already something bound to that receptor (i.e. car into a parking space) o …chemistry of neurotransmitter and receptor matches (i.e. key into a lock) • Once transmission has completed, neurotransmitter is released back into synapse (where it is either decomposed by enzymes or reabsorbed by the sending neuron) Neurotransmitters and Their Functions • Acetylcholine o Involved in muscle contraction, learning, and memory o Low levels of acetylcholine linked to memory loss and Alzheimer's disease • GABA o Highly concentrated in the brain o Inhibits neural activity o Low levels of GABA linked to anxiety and depression • Glutamate o Highly concentrated in the brain o Excited neural activity o Low levels of glutamate linked to poor learning ability, non-commensurate emotional responses, and memory failure • Dopamine o Helps control voluntary movement, affects sleep, mood, attention, and learning o High levels of dopamine linked to some psychological disorders (e.g. schizophrenia) o Low levels of dopamine linked to Parkinson's disease • Norepinephrine o Stress stimulates release of norepinephrine o Inhibits firing of neurons in central nervous system, by excites heart and digestive functions o Low levels of norepinephrine linked to mood disorders and experience of depression; high levels linked to agitation • Endorphins o Stimulate firing of neurons; depress nervous system activity o Manipulations of endorphin activity in brain is associated with pain and pleasure (high enorphins, low pain) o Linked to expressions of emotional behavior (e.g. fear, tension, euphoria) • Serotonin o All production of serotonin occurs within the brain stem, an area responsible for regulation of arousal states; however, pathways exist throughout much of the brain o Abnormally high and low levels of serotonin linked to mood disorders o LSD suppresses release of serotonin o Low levels associated with depression o Antidepressants (Selective Serotonin Reuptake inhibitors (SSRI)) serve to increase levels in system by blo
More Less

Related notes for PSY 101

Log In


Don't have an account?

Join OneClass

Access over 10 million pages of study
documents for 1.3 million courses.

Sign up

Join to view


By registering, I agree to the Terms and Privacy Policies
Already have an account?
Just a few more details

So we can recommend you notes for your school.

Reset Password

Please enter below the email address you registered with and we will send you a link to reset your password.

Add your courses

Get notes from the top students in your class.