Presentation on theme: "The Biological Bases of Behavior (Chapters 2 and 4)"— Presentation transcript:
1 The Biological Bases of Behavior (Chapters 2 and 4) AP Psychology Unit 2:The Biological Bases of Behavior (Chapters 2 and 4)
2 An Early History of Biopsychology Plato: the mind is located in the brainFranz Gall and PhrenologyEarly 1800sRead bumps on skull to understand traitsTouch my sexy head lumps. Go on….touch them!
3 Biopsychology TodayEverything we do is ultimately controlled by our body and brainBody/brain composed of cellsBrain cells called neurons communicate electrically and chemicallyDifferent parts of the brain have specific functionsOur brains create meaningful experiences from sensory informationBrain structure and function is influenced by experience
4 Neurons: Defining and Types A NEURON is a nerve cell.There are three basic types of neurons (diagram):Sensory Neurons: Afferent neurons that detect stimuli from sense organs and relay this information TO the brain and/or spinal cord.Motor Neurons: Efferent neurons that receive signals from the brain and/or spinal cord and relay this information to glands and muscles.Interneurons: neurons in the brain and spinal cord that coodinate activity between sensory and motor neurons.Three Types of Neurons in action!Glial Cells: provide nutrients to neurons, insulate neurons, and remove debris when neurons die.
6 The Neural Impulse (diagram) Intraneural transmission: within on neuronThis is an ELECTRICAL processOccurs as a result of the exchange of charged particles called ions
7 Neural Impulse: Resting Potential When more negative ions are inside the neuron than outsideNeuron is not transmitting informationSimilar to a compressed springThe neuron is POLARIZED – meaning it has a charge (-)System WANTS to reach equilibrium and balance charges, but selectively permeable membrane is closed when in this state known as resting potential
8 Neural Impulse: Action Potential Sudden, massive change in charge in the neuronNeuron reaches the threshold of excitation when neighboring neurons’ excitatory signals outnumber inhibitory signalsIons flow across cell membrane down axon (domino effect) facilitated by myelin sheathNa+ in, K+ outNeuron fires and DEPOLARIZES – no charge
9 Neural Impulse: All-or-None Law A neuron either fires or it does notWhen it does fire, it will always produce an impulse of the same strengthIntensity of a stimulus is coded by the frequency of action potentials or the number of neurons that fire
10 Neural Impulse: Refractory Dude…I’m in refractory. No action potential here…Absolute refractory periodPeriod immediately after an action potential when another action potential cannot occurRelative refractory periodPeriod following absolute refractory period when a neuron will only respond to a stronger than normal impulseDuring the refractory period, the neuron is trying to get back to resting potential by pumping out K+ ions!Hmpf.
11 So…? Impulse has traveled down the length of the axon Signal end up at terminal buttons, very end points of the axon terminalsThen what?Signal must get to other neurons, but how?
12 The Synapse (diagram) The synapse Synaptic space (synaptic cleft) Composed of the terminal button of one neuron, the synaptic space, and the dendrites or cell body of the receiving neuronSynaptic space (synaptic cleft)Tiny gap between neuronsMessages must travel across the space to get from one neuron to the next
13 Transmission Between Neurons PresynapticNeuronInterneural: between neuronsa CHEMICAL processSynaptic vesiclesSacs in terminal button that release chemicals into synaptic spaceNeurotransmittersChemicals released by synaptic vesiclesReceptor sitesLocation on receptor neuron for specific neurotransmitterLock and keyReuptake“Recycling” neurotransmittersPostsynapticNeuron
15 Neurotransmitters and Behavior (diagram) Neurotransmitters regulate many aspects of behaviorAn imbalance of neurotransmitters may cause maladaptive behaviorNeurotransmitters may be inhibitory, excitatory or both
16 Drugs and Neurotransmitters Drugs’ impact on the body has helped scientists discover neurotransmitters, neuropeptides (e.g. amino acids such as endorphins) and neuromodulators that can increase or decrease the activity of certain neurotransmittersHow do drugs work?Agonists mimic or prevent reuptake (1, 3)Antagonists block neurotransmission (2)
17 Psychopharmacology Botulism Blocks release of ACh at the neuromuscular junction, causing paralysis“Botox” is botulism toxin used to prevent facial muscles from making wrinklesCurare – found in vines in S. America; used as poisonCan stun or kill prey quicklyBlocks ACh receptors causing paralysisAntipsychotic medicationsBlock dopamine receptorsReduces schizophrenic hallucinationsCaffeineIncreases the release of excitatory neurotransmitters by blocking the inhibitory neurotransmitter adenosineCocainePrevents reuptake of dopamineLeads to heightened arousal of entire nervous system
19 The Autonomic Nervous System (diagram) Fight-or-flight responseSympathetic: ArousesParasympathetic: Calms
20 Central Nervous System (CNS) BrainSpinal CordBrainEnables all functioningBillions of neurons and their connectionsThese neurons work together in neural networks to facilitate efficient output.As we learn, these networks strengthenSpinal CordConnects brain to PNSHandles reflexesI rule.
21 The Endocrine System (diagram) Tell me about it!I hate being naked in front of all these students…Helps coordinate and integrate complex psychological reactionsEndocrine glands secrete hormones into the bloodstreamHormones serve to organize the nervous system and bodyHormones also activate behavior, such as sexual behavior, hunger and aggression
22 Endocrine Glands (diagram) Dunno.Got diabeeetus?Endocrine Glands (diagram)diabeetusfetusThyroid glandSecretes hormones (primarily thyroxin) that control metabolismHypothyroidism and HyperthyroidismPineal glandSleep-wake cycleSecretes melatoninPancreasRegulates blood-sugar levelsSecretes insulinDiabetes?Pituitary glandReferred to as the “master gland”regulates many other glandsAdrenal glandsReaction to stressSecretes adrenaline (epinephrine)GonadsOvaries and testessecrete estrogens and androgens
23 The Brain Without our brains, we would really be nothing! “The mind is what the brain does”
24 Studying the Brain Studying the brain through lesions or damaged areas “Ta” and Phineas GageExperiments in rats – hypothalamus lesionsMonitoring Electrical Activity: the EEGElectroencephalograms provide information about cortical activityRecord electrical activity of neurons on surface of brain (neural firing)A functional technique
25 Studying the Brain: Structural Neuroimaging Techniques CT Scan (Computerized tomography)Computer-assisted x-ray of brainUsed to create overall images of brainMRI (Magnetic Resonance Imaging)Produces detailed pictures of soft tissue in brainCan focus on specific regions when CT cannot produce clear imagesCT scan (top) and MRI (bottom) showing a tumor.
26 Studying the Brain: Functional Neuroimaging Techniques PET (positron emission tomography)Image created by the rate at which radioactive glucose is metabolizedWhich areas of the brain are active during a particular activityfMRI (functional MRI)Combines structural and functional techniquesMultiple images of brain created during a particular taskRecords changes in blood flow to indicate regions of greater activity
27 Primitive Brain Structures BrainstemOldest part of brainContains medulla, controlling heartbeat, blood pressure and breathingAlso contains pons, which helps regulate sensory information and facial expressionsContains Reticular Formation (RF) for alertness/arousal, sleep/wakefulnessThalamusPair of egg-shaped structures on top of brainstemRoutes all incoming sensory information except for smell to appropriate areas of brainCerebellum“little brain” at read of brainstemControls coordination, balance, and muscle toneThese parts of the brain are our “autopilot” so other regions can deal with higher-level “human” functions
28 The Limbic SystemLocated in between the primitive parts of the brain and the cerebral hemispheresHippocampus processes new memories (case of H.M.)Amygdala controls emotions such as aggression and fear – in animals, the “attack” response (rat study)Hypothalamus regulates hunger, thirst, body temperature and sex drive – also controls pituitary glandRat study – self-stimulation of “pleasure centers”Human implications? Mild pleasure, addiction tendencies?Primarily, the limbic system processes drives, smell and various emotional responses
29 The CortexPart of the cerebrum, the two large hemispheres comprising 85% of brain weightWrinkled outer layerWhy so convoluted?Higher level functionsDesignation of cortical space and “higher level” animals?Most highly evolved part of the human brain
30 Cortex Breakdown… Each hemisphere is divided into 4 lobes Frontal lobeTemporal lobeParietal lobeOccipital lobeThe lobes are separated by deep convolutions known as fissures
31 Cortex Breakdown… Occipital Lobes Temporal Lobes Parietal Lobes Homunculous!Cortex Breakdown…Occipital LobesVisual cortexDamage?Temporal LobesAuditory cortexAuditory hallucinations?Parietal LobesPrimary sensory or somatosensory cortexAllocation of space?Frontal LobesMost evolvedMotor cortex, which allows us to move
33 The Cortex: Association Areas We only use 10% of our brains?Undifferentiated cortexAssociation areas
34 Phineas Gage: A Case Study in Frontal Lobe Association Area Damage In 1848, railroad foreman Phineas Gage – accident!No longer “himself”Emotions, the frontal cortex, and the unchecked limbic systemThe skull of Phineas and rogue tamping iron, displayed proudly at Harvard University’s medical school! For real!
35 Hey guys! Check out our phat crib! NeuroplasticityShafted again.Brain’s to change and reorganize as a result of experienceMark Rosenzweig’s ( ) Rat Studies (1950s-60s)Implications for humans?Hey guys! Check out our phat crib!Party!
38 Neurogenesis?Recent evidence has suggested that human brains may be able to generate new brain cells, known as NeurogenesisStem cell research?
39 The Two Hemispheres Two halves are NOT identical Most have a dominant hemisphere – usually the left, which controls the right side of the bodyBoth sides serve important functions, revealed by studying split-brain patients
40 Split-Brain Epilepsy, seizures and the corpus callosum Reduction in epileptic seizuresDifferent abilities in each hemisphereThe story of “Vicki”Michael Gazzaniga
41 Some Hemispheric Strengths Left HemisphereLanguage in most people: The cases of Ta of Charles LandryLogicRight side of bodyRight HemispherePerceptionSense of selfInferences
42 Hemispheric Dominance: Handedness 90% of humans are right-handedThe 10% of left-handers show less predictable patterns of hemispheric dominanceCauses?Genetics?Fetal testosterone levels?Learned?Handedness and sexual orientation?A closer look: a curse or an advantage?
43 Behavior Genetics: What’s the Point? Behavior Genetics seeks to understand the relative influence of our heredity and our experiencesNature vs. Nurture? It’s both – but how much of each?
44 Behavior Genetics: Genetics Review Heredity examines the transmission of trait from one generation to nextChromosomesPairs of thread like bodies that contain genesAverage human cell has 23 pairsSex cells?Deoxyribonucleic acid (DNA)Organic molecule arranged in a double-helixContains the “code of life”GenesBasic units of inheritanceSegment of DNAGenome“map” for an organism’s genetic complete make-upHuman Genome Project
46 Behavioral Genetics: Temperament and Heritability Temperament refers to emotional reactivity and seems to be set very early in lifeThomas and Chess (easy, difficult, slow-to-warm-up)Kagan’s “shy child”Indicates this aspect of behavior is genetically manipulatedEnvironment can enhance or diminish this genetic predisposition
47 Behavior Genetics: Heritability Heritability: the extent to which differences among organisms are caused by genesDoes NOT refer to which percentage of a trait is determined by genetics in a given individual!The more similar and controlled the environment of the organisms is, the more we can attribute differences to genes, and the higher the heritability!
48 So…Nature vs. Nurture…?Genes and environment interact like “two hands clapping…”Environment can trigger genetic “switches”Our genes can provoke us to seek particular environmentse.g. Eating DisordersGenetic predisposition (some are more susceptible than others)Cultural regulation (Western culture)Molecular GeneticsStudies how particular genes influence behaviore.g. Is there a gene that determines obesity? Sexual orientation?Promise and peril of molecular genetics?Genetic engineeringEugenics
49 Evolutionary Psychology Whereas behavior geneticists seek to explain our behavioral differences in terms of our genes, evolutionary psychologists focus on our similarities, as dictated by natural selection.Richard Dawkins The Selfish Gene (1976)Varied organisms in a population compete to surviveCertain biological and behavioral variations facilitate survivalSurviving organisms may reproduce and pass on their genesThis leads to overall changing characteristics in a population
50 Evolutionary Psychology: Natural Selection, Adaptation and Evolutionary Success Selection – providing a reproductive advantage, either naturally or artificially (e.g. tame foxes), based on a trait/set of traitsThese traits will endure over timePopulation will change as a resultVariation can result from mutations (errors in genetic replication right after conception)Some of these “errors” provide an advantage and are selected for, and therefore persistThe errors are adaptive – increasing our fitness, or our chances to survive (and to reproduce)Humans have so many shared characteristics – How?Differences that were not “fit” were not passed onThose that increased survival were, as these organisms lived and reproduced
51 Evolutionary Psychology Selection happens SLOWLY and often our world changes faster than the gene pool can (e.g. fatty/sweet food cravings)Today, evolutionary psychologists examine persistent trends in human behavior and seek to explain themKeep in mind, however, that genetically driven tendencies only partially govern human behavior!
52 Evolutionary Psychology: Explaining Human Sexuality and Mating Males of all sexualities generally are more interested in sex, regard sex as a recreational activity and prefer young, attractive matesFemales of all sexualities generally see sex as an outgrowth of relationships and prefer mature, stable, and affluent matesHave these trends genetically motivated?
53 Evolutionary Psychology: Human Sexuality and Mating WomenQuality over quantityMore invested in bearing/nurturing childrenSeek men who either provide superb genes (he-man strategy) or are good providers (domestic-bliss strategy)“fast” vs. “coy” femalesMenQuantity over qualityIncrease reproductive success by spreading their genes as widely as possibleAttraction to fertile femalesNot physically bound to pregnancyHe-man strategy vs. opportunistsPhilanderers vs. Stable males?Perhaps males should invest more in child-rearing?
54 Evolutionary Psychology: Criticism Do these arguments just provide excuses for bad behavior?Do humans have more of a social and cultural responsibility to make the world better?What about environmental influence?How does the environment reinforce these trends?How much of a role does environment play in the persistence of these roles?Who benefits?
55 Parents and Peers Experience and Brain Development Parental Influence? Critical PeriodsRosenzweig revisitedBrains are shaped by our genes AND experienceParental Influence?If abusive or neglectful, can have major impactIn non-extreme cases, parents probably deserve less credit, or less blame!Parents shape values, beliefs and habits, but not as much as we may believeMost important to provide unconditional love and supportPeer InfluencePeers teach us how to socialize and cooperateSelection effect: seeking peers with similar interests
56 Cultural Influences Culture Norms distinctive values, beliefs, language and characteristics of a societyboth tangible (food, clothing) and intangible (values, beliefs).NormsRules that represent the typical behaviors of a particular groupOne example is expected personal space, the distance we like to keep ourselves from other people
57 Individualism vs. Collectivism Individualist cultures place value of singular person over that of the groupCollectivist cultures value the group over the individualWhich type of culture does the US have? Why?Implications?
58 Gender Development Aggression, Power, and Connectedness Aggression involves an intent to harm, whether verbal or physical: males admit to and exhibit more than females.Men are and are perceived as more powerful and engage in behaviors that exhibit and perpetuate this power inequity.Females place greater emphasis on social connections, choosing careers that involve social interaction or require nurturing rolesMales have more difficulty admitting they are wrong
59 Why Are We Different? Biological Explanations X and Y ChromosomesY triggers sex differentiation during fetal development, causing greater testosterone production in malesFemale infants exposed to elevated levels of testosterone exhibit “male” behavioral characteristicsMales with normal male hormones but had their sex reassigned at birth for various reasons often embrace a male identity, despite efforts to raise them as females
60 Why Are We Different? Social Explanations Gender Roles – expected behaviors for males and femalesWomen as caregivers?Men as breadwinners?The Reality? Women now OUTNUMBER men in the workplace in the US, yet in 87% of families with children, are still the primary caregivers.Variations across culture and time…Gender Identity – our sense of being male or femaleGender typing – embracing a traditional masculine/feminine roleSocial Learning Theory and Gender SchemasWhat do these roles and stereotypes provide for us?Sense of stability and simplificationSense of confinement
61 Nature vs. Nurture? Call the Whole Thing Off! Our genes and our experiences form usFamily, friends, and culture have an influence over the genes that make usThese structures are constantly in fluxWe are adaptive creaturesThe world changes, and we change with it