AP Psychology Unit 2:

1. 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 brain • Franz Gall and Phrenology • Early 1800s • Read bumps on skull to understand traits

3. Biopsychology Today • Everything we do is ultimately controlled by our body and brain • Body/brain composed of cells • Brain cells called neurons communicate electrically and chemically • Different parts of the brain have specific functions • Our brains create meaningful experiences from sensory information • Brain 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.

5. Neuroanatomy (diagram)

6. The Neural Impulse (diagram) • Intraneural transmission: within on neuron • This is an ELECTRICAL process • Occurs 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 outside • Neuron is not transmitting information • Similar to a compressed spring • The 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 neuron • Neuron reaches the threshold of excitation when neighboring neurons’ excitatory signals outnumber inhibitory signals • Ions flow across cell membrane down axon (domino effect) facilitated by myelin sheath • Na+ in, K+ out • Neuron fires and DEPOLARIZES – no charge

9. Neural Impulse: All-or-None Law • A neuron either fires or it does not • When it does fire, it will always produce an impulse of the same strength • Intensity of a stimulus is coded by the frequency of action potentials or the number of neurons that fire • In other words, if there are several neighboring neurons firing, or one neuron firing repeatedly, the stimulus may be intense enough for the neuron to fire.

10. Neural Impulse: Refractory • Absolute refractory period • Period immediately after an action potential when another action potential cannot occur • Relative refractory period • Period following absolute refractory period when a neuron will only respond to a stronger than normal impulse • During the refractory period, the neuron is trying to get back to resting potential by pumping out K+ ions!

11. So…? • Impulse has traveled down the length of the axon • Signal end up at terminal buttons, very end points of the axon terminals • Then what? • Signal must get to other neurons, but how?

12. The Synapse (diagram) • The synapse • Composed of the terminal button of one neuron, the synaptic space, and the dendrites or cell body of the receiving neuron • Synaptic space (synaptic cleft) • Tiny gap between neurons • Messages must travel across the space to get from one neuron to the next

13. Transmission Between Neurons Presynaptic Neuron • Interneural: between neurons • a CHEMICAL process • Synaptic vesicles • Sacs in terminal button that release chemicals into synaptic space • Neurotransmitters • Chemicals released by synaptic vesicles • Receptor sites • Location on receptor neuron for specific neurotransmitter • Lock and key • Reuptake • “Recycling” neurotransmitters Postsynaptic Neuron

14. Putting it together…

15. Neurotransmitters and Behavior (diagram) • Neurotransmitters regulate many aspects of behavior • An imbalance of neurotransmitters may cause maladaptive behavior • Neurotransmitters 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 neurotransmitters • How 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 wrinkles • Curare – found in vines in S. America; used as poison • Can stun or kill prey quickly • Blocks ACh receptors causing paralysis • Antipsychotic medications • Block dopamine receptors • Reduces schizophrenic hallucinations • Caffeine • Increases the release of excitatory neurotransmitters by blocking the inhibitory neurotransmitter adenosine • Cocaine • Prevents reuptake of dopamine • Leads to heightened arousal of entire nervous system

18. Endocrine System + Nervous System= Two Peas in a Pod? • All of our physical and emotional reactions are the product of communication between the brain and the rest of the body • Endocrine System = Glands (hormones) • Nervous System = Neurons • Our brain is the “supercomputer” and may instruct our glands to release hormones AS IT IS instructing the neurons in the central and peripheral nervous systems to fire • Example: You are being chased by a bear! • Brain -> Endocrine- Release adrenaline from adrenal gland • Brain -> CNS- communicate via epinephrine (NT) to excite SNS

19. The Endocrine System (diagram) Tell me about it! I hate being naked in front of all these students… • Helps coordinate and integrate complex psychological reactions • Endocrine glands secrete hormones into the bloodstream • Hormones serve to organize the nervous system and body • Hormones also activate behavior, such as sexual behavior, hunger and aggression • Slower communication than Nervous System (but impacts last longer)

20. Endocrine Glands (diagram) • Thyroid gland • Secretes hormones (primarily thyroxin) that control metabolism • Hypothyroidism and Hyperthyroidism • Pineal gland • Sleep-wake cycle • Secretes melatonin • Pancreas • Regulates blood-sugar levels • Secretes insulin • Diabetes? • Pituitary gland • Referred to as the “master gland” • regulates many other glands • Adrenal glands • Reaction to stress • Secretes adrenaline (epinephrine) • Gonads • Ovaries and testes • secrete estrogens and androgens Brain  Pituitary  other glands  hormones  brain

21. The Nervous System (diagram)

22. Peripheral Nervous System: Somatic • Afferent and Efferent neurons carry messages to and from central nervous system to glands/muscles

23. Peripheral Nervous System: Autonomic (diagram) • Fight-or-flight response • Sympathetic: Arouses • Parasympathetic: Calms

24. Central Nervous System (CNS) Central Nervous System • Brain • Enables all functioning • Billions of neurons and their connections • These neurons work together in neural networks to facilitate efficient output. • As we learn, these networks strengthen • Spinal Cord • Connects brain to PNS • Handles reflexes Brain Spinal Cord I rule.

25. The Brain • Without our brains, we would really be nothing! • “The mind is what the brain does” • Brain + Body = Mind • We live somewhere “north of the neck” • What would happen if our brains were placed into another human’s body?

26. Studying the Brain • Studying the brain through lesions or damaged areas • “Ta” and Phineas Gage • Experiments in rats – hypothalamus lesions • Monitoring Electrical Activity: the EEG • Electroencephalograms provide information about cortical activity • Record electrical activity of neurons on surface of brain (neural firing) • A functional technique

27. Studying the Brain: Structural Neuroimaging Techniques • CT Scan (Computerized tomography) • Computer-assisted x-ray of brain • Used to create overall images of brain • MRI (Magnetic Resonance Imaging) • Produces detailed pictures of soft tissue in brain • Can focus on specific regions when CT cannot produce clear images CT scan (top) and MRI (bottom) showing a tumor.

28. Studying the Brain: Functional Neuroimaging Techniques • PET (positron emission tomography) • Image created by the rate at which radioactive glucose is metabolized • Which areas of the brain are active during a particular activity • fMRI (functional MRI) • Combines structural and functional techniques • Multiple images of brain created during a particular task • Records changes in blood flow to indicate regions of greater activity

29. Primitive Brain Structures • Brainstem • Oldest part of brain • Contains medulla, controlling heartbeat, blood pressure and breathing • Also contains pons, which helps regulate sensory information and facial expressions • Contains Reticular Formation (RF) for alertness/arousal, sleep/wakefulness • Thalamus • Pair of egg-shaped structures on top of brainstem • Routes all incoming sensory information except for smell to appropriate areas of brain • Communicates with higher level of brain • Penn Station • Cerebellum • “little brain” at read of brainstem • Controls coordination, balance, and muscle tone These parts of the brain are our “autopilot” so other regions can deal with higher-level “human” functions

30. The Limbic System • Located in between the primitive parts of the brain and the cerebral hemispheres • Hippocampus 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 gland • Rat study – self-stimulation of “pleasure centers” • Human implications? Mild pleasure, addiction tendencies? • Primarily, the limbic system processes drives, smell and various emotional responses

31. The Cortex • Part of the cerebrum, the two large hemispheres comprising 85% of brain weight • Wrinkled outer layer • Why so convoluted? • Higher level functions • Designation of cortical space and “higher level” animals? • Most highly evolved part of the human brain

32. Cortex Breakdown… • Each hemisphere is divided into 4 lobes • Frontal lobe • Temporal lobe • Parietal lobe • Occipital lobe • The lobes are separated by deep convolutions known as fissures

33. Cortex Breakdown… Homunculous! • Occipital Lobes • Visual cortex • Damage? • Temporal Lobes • Auditory cortex • Auditory hallucinations? • Parietal Lobes • Primary sensoryorsomatosensory cortex • Allocation of space? • Frontal Lobes • Most evolved • Motor cortex, which allows us to move • Allocation of space?

34. Motor and Sensory Cortex Revealed!

35. The Cortex: Association Areas • We only use 10% of our brains? • Undifferentiated cortex • Association areas

36. 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 system The skull of Phineas and rogue tamping iron, displayed proudly at Harvard University’s medical school! For real!

37. Neuroplasticity Shafted again. • Brain’s ability to change and reorganize as a result of experience • Mark Rosenzweig’s (1922-2009) 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 Neurogenesis • Stem 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 body • Both sides serve important functions, revealed by studying split-brain patients

40. Split-Brain • Epilepsy, seizures and the corpus callosum • Reduction in epileptic seizures • Different abilities in each hemisphere • The story of “Vicki” • Michael Gazzaniga

41. Some Hemispheric Strengths • Left Hemisphere • Language in most people: The cases of Ta of Charles Landry • Logic • Right side of body • Right Hemisphere • Perception • Sense of self • Inferences

42. Hemispheric Dominance: Handedness • 90% of humans are right-handed • The 10% of left-handers show less predictable patterns of hemispheric dominance • Causes? • 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 experiences • Nature 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 next • Chromosomes • Pairs of thread like bodies that contain genes • Average human cell has 23 pairs • Sex cells? • Deoxyribonucleic acid (DNA) • Organic molecule arranged in a double-helix • Contains the “code of life” • Genes • Basic units of inheritance • Segment of DNA • Genome • “map” for an organism’s genetic complete make-up • Human Genome Project

45. Behavioral Genetics:Studying Nature vs. Nurture • Animal Studies • Strain Studies • Selection Studies • Human Studies • Identical Twins • Fraternal Twins • Separated Twins • Adoption Studies • Family studies

46. Behavioral Genetics:Temperament and Heritability • Temperament refers to emotional reactivity and seems to be set very early in life • Thomas and Chess (easy, difficult, slow-to-warm-up) • Kagan’s “shy child” • Indicates this aspect of behavior is genetically manipulated • Environment can enhance or diminish this genetic predisposition

47. Behavior Genetics: Heritability • Heritability: the extent to which differences among organisms are caused by genes • Does 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 environments • e.g. Eating Disorders • Genetic predisposition (some are more susceptible than others) • Cultural regulation (Western culture) • Molecular Genetics (Behavioral Genetics) • Studies how particular genes influence behavior • e.g. Is there a gene that determines obesity? Sexual orientation? • Promise and peril of molecular genetics? • Genetic engineering- successful in breeding “intelligent” rats • Eugenics- Blood tests before marriage; prescreening for genetic disorders

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 survive • Certain biological and behavioral variations facilitate survival • Surviving organisms may reproduce and pass on their genes • This 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 traits • These traits will endure over time • Population will change as a result • Variation can result from mutations (errors in genetic replication right after conception) • Some of these “errors” provide an advantage and are selected for, and therefore persist • The 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 on • Those that increased survival were, as these organisms lived and reproduced