Chapter two Neuroscience and Biological Founda-ons

Transcription

1 Chapter two Neuroscience and Biological Founda-ons Our Gene-c Inheritance Neural Bases of Behavior Nervous System Organiza-on A Tour Through the Brain realworldpsychology Things You ll Learn in Chapter 2 Q1 Q2 Q3 Q4 Q5 Can our genes influence whom we vote for in presidenaal elecaons? Why can spending the first few months of life in an orphanage lead to long- term problems in cogniave funcaoning? How can a chemical in the brain lead rats to binge- eat M&Ms? How can stem cell injecaons lead to restored vision and improved recovery from strokes? Why are former NFL athletes at increased risk of depression, demenaa, and suicide? OUR GENETIC INHERITANCE 1

2 Behavior Genetics The study of how heredity and environment affect us EvoluAonary psychology = the applica-on of principles of evolu-on to explain behavior and mental processes Genes control the transmission of traits Modern research shows most human characteris-cs are polygenic (controlled by mul-ple genes, not merely one dominant or two recessive genes) Virtual Field Trip: Reading Your DNA Most serious gene-c disorders are not transmiued by dominant genes. Why? realworldpsychology Most people understand that genes affect our health, such as poten-al for heart disease, diabetes, and cancer Genes also affect our personality traits, behavioral habits, sexual orienta-on, and psychological disorders Q1 Can our genes influence whom we vote for in presidenaal elecaons? Genes can even influence which poli-cal party we side with, and our views on death penalty, unemployment, and abor-on (Hatemi & McDermoU, 2012) Video: Lifespan Gene Video: Genome ABCs Gene- Environment Interaction Environmental factors both physical and psychological also influence our characteris-cs Malnourished children may not reach their full poten-al gene-c height or maximum intelligence Video: Gene Therapy Safety Tutorial Video: The InteracAon of Genes and Environment 2

3 Genes vs. Environment Iden-cal twins share all their genes, How can fraternal twins share about half of their psychologists genes (just like non- twin siblings) separate gene-c Twins raised together by birth parents causes from share the same environment environmental Iden-cal twins should be more alike than causes? fraternal twins (such as in intelligence) Research on adop-ve children can trace characteris-cs to birth parents vs. adop-ve parents Research shows many psychological traits (and disorders) run in biological families Heritability Heritability = the percentage of varia-on in a popula-on auributable to heredity If no gene-c influence, heritability would be 0% If no environmental influence, heritability would be 100% Heritability does NOT apply to INDIVIDUALS Heritability does not trump environment Evolutionary Psychology Many behaviors emerged and s-ll exist because they helped our ancestors survive Natural selecaon = par-cular gene-c trait gives an organism a reproduc-ve advantage Reproduc-on of the fiuest, not survival of the fiuest Video: What Sex Is Your Brain? 3

4 NEURAL BASES OF BEHAVIOR The Basics Building blocks of brain and nervous system: Neurons = responsible for receiving, processing, and transmihng electrochemical informa-on Glial cells = provide structure, nutri-on and other support to neurons Video: Stem Cell Shakes Parts of a Neuron Dendrites = branching fibers that receive impulses from other neurons and send them to the cell body Cell body = AKA soma, contains cell nucleus Axon = long, tube- like structure that sends impulses away from cell body to other neurons (or to muscles, glands) Video: Cell Scouts 4

5 Action Potential Action Potential Sequence of depolariza-on and repolariza-on moves the ac-on poten-al from the cell body to the axon terminal buuons like the wave Electricity moves 36 million meters/second Nerve impulses move 10 meters/second Nerve impulses move 10x faster through axons with myelin sheath Q2 Speed of Thought Why can spending the first few months of life in an orphanage lead to long- term problems in cogniave funcaoning? Social isola-on during early weeks/months of life (as for babies in orphanage) prevents proper growth of myelin, leading to long- term cogni-ve impairment 5

6 Communication Between Communica-on WITHIN neuron is electrical, but communica-on BETWEEN neurons is chemical Sending neuron gets close to receiving neuron at synapac gap, where neurotransmi[ers (chemicals) cross the gap to deliver the message How Neurotransmitters Work Reuptake Lock and Key 6

7 Common Neurotransmitters Endorphins Common neurotransmiuer elevate mood, reduce pain Opium- based drugs mimic the body s natural endorphins Q3 How can a chemical in the brain lead rats to binge- eat M&Ms? Endorphins affect memory, learning, appe-te, and sexual ac-vity. Rats injected with endorphins ate 5% of their body weight in M&Ms! Video: Brain Viagara Hormones & the Endocrine System Endocrine system = network of glands located throughout the body that secretes hormones into the bloodstream Neurons send messages to certain receptors; hormone messages are carried by the blood to any cell that will listen Regulates and maintains long- term body processes, such as growth, sexual characteris-cs, diges-on, and elimina-on Controls response to emergencies: adrenal glands release cor-sol, epinephrine, and norepinephrine 7

8 NERVOUS SYSTEM ORGANIZATION Central Nervous System (CNS) CNS is powerful, but fragile NeuroplasAcity = brain can reorganize its func-onal structure due to usage and experience Q4 How can stem cell injecaons lead to restored vision and improved recovery from strokes? Neurogenesis = lost cells can be replaced by neural stem cells (rare immature cells that can migrate and grow into any type of cell). No cell transplant for spinal cord injuries in humans, but animal research shows stem cell treatment leads to improvement in paralyzed limbs Video: Mending Broken Hearts 8

9 Spinal Cord Relays AND ini-ates vital informa-on to other parts of the body Reflexes = automa-c behavior in response to s-muli Allows immediate ac-on without delay of rou-ng through brain What is the evolu-onary benefit of the reflex arc? Newborn ReLlexes A B C RooAng reflex Lightly stroke the cheek and watch how the infant automa-cally (reflexively) turns toward the s-mula-on and auempts to suck Grasping Reflex Place your finger or an object in the infant s palm and note the automa-c grasp Babinski Reflex Lightly stroke the sole of the foot, and the big toe will move toward the top, while the other toes fan out. Peripheral Nervous System (PNS) The part of the nervous system outside the brain and spinal cord Carries informa-on to and from the CNS Links brain and spinal cord to body s sense receptors, muscles and glands SomaAc nervous system (SNS): carries sensory informa-on to the brain and instruc-ons back to skeletal muscles Autonomic nervous system (ANS): responsible for involuntary tasks like heart rate, diges-on, and breathing 9

10 Autonomic Nervous System SympatheAc division: mobilizes energy to respond to stressor (fight or flight) ParasympatheAc division: calms body to conserve energy, returns body to normal func-oning ater stress A TOUR THROUGH THE BRAIN Biological Tools for Research Virtual Field Trip: Neuroimaging 10

11 Biological Tools for Research (cont.) Forebrain Limbic System The interconnected group of forebrain structures involved with emoaons, drives, and memory, as well as major physiological funcaons Cerebral Cortex The thin surface layer that regulates most complex behavior (i.e. sensaaons, motor control). AnimaAon: The Brain Limbic System Hippocampus Seahorse shaped part of the limbic system involved in forming and retrieving memories Amygdala Part of the limbic system that controls emoaons, like aggression and fear. 11

12 realworldpsychology Cerebral cortex = surface layer of the brain Responsible for most complex behaviors and higher mental processes Damage to cerebral cortex linked to substance abuse, demen-a, and suicide Q5 Why are former NFL athletes at increased risk of depression, demenaa, and suicide? Trauma is par-cularly common in contact sports, like football, ice hockey, boxing, and soccer Lobes Tutorial Video: Build a Brain Learning AcAvity Tutorial Video: DissecAng the Brain realworldpsychology In 1848, 25- year- old railroad worker Phineas Gage had a metal rod accidentally blown through the front of his face, destroying much of his brain s frontal lobe Experienced dras-c personality changes; became impa-ent and lacked concern for coworkers He eventually obtained a job driving a stagecoach, which required high motor, cogni-ve, and interpersonal skills Video: Kid Concussions What does modern research about neuroplas-city tell us about Gage s possible recovery? 12

13 Two Brains in One? Each hemisphere controls the opposite site of the body Corpus callosum = thick band of nerves, connects the two hemispheres Although each side of the brain might have a specialty (like Broca s area for speech in the let hemisphere), when specific regions of the brain are injured or destroyed their func-ons can be assumed by neighboring region or even opposite hemisphere realworldpsychology Popular myth says let brain is analy-cal and right brain manages crea-vity Research shows both hemispheres work together in an integrated manner, like teammates playing soccer; each area might have special-es, but everyone knows what the other is doing and can help when needed Video: Watching Living Brains 13