Biological Level of Analysis: Physiology and Behavior


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Section 2.1 in the IB Psychology textbook

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Biological Level of Analysis: Physiology and Behavior

  1. 1. Biological Level of Analysis Physiology and Behavior
  2. 2. Principles • There are physiological origins of many behaviors • Human beings should be studied as biological systems • Consider how the environment and cognition may interact with biological systems and affect physiology – Biology can affect cognition and vice versa
  3. 3. Physiology • Some physiological factors which can affect behavior: – Brain processes – Neurotransmitters – Hormones – Genes • Physiology responds to environmental stimuli
  4. 4. Physiology • Nature versus nurture debate: – Is human nature the result of environmental factors or biological factors? • Interactionist approach: – Mix of the two arguments – Holistic picture of human behavior – This is the goal of I.B. Psychology
  5. 5. Principles • Behavior can be innate because it is genetically based – Thus, evolution plays a key factor in behavior • Animal research can provide insight into human behavior • There are biological correlates of behavior – Should be possible to find links between biological factors and specific behaviors
  6. 6. Principles • Reductionist approach is commonly used – Micro-level of research – Breaks down complex human behavior into its smallest parts – Could be overly simplistic, but it is detailed
  7. 7. Neurotransmission • Neurotransmission underlies behavior: NEUROTRANSMITTER EFFECT ON BEHAVIOR Acetylcholine •Muscle contraction •Affects memory in hippocampus Dopamine •Voluntary movement •Learning •Pleasure Noradrenaline •Arousal •Alertness •Stimulation of sympathetic nervous system Serotonin •Sleep •Arousal levels •Emotion
  8. 8. Kasamatsu and Hirai (1999) • Aim: See how sensory deprivation affects the brain • Method: Studied Buddhist monks on a 3-day pilgrimage – No food or water, no speaking, cold weather – Started hallucinating after 48 hours • Blood samples before and after pilgrimage: – Serotonin levels heightened – Serotonin activated hypothalamus and frontal cortex = hallucinations – Sensory deprivation = release more serotonin
  9. 9. Martinez and Kesner (1991) • Aim: Determine the role of the neurotransmitter acetylcholine on memory • Method: Rats in a maze – One group of rats given scopolamine to block acetylcholine from being transmitted – Second group given physostigmine which keeps cholinesterase from monitoring levels of acetylcholine – Third group as control
  10. 10. Martinez and Kesner (1991) • Results: – (First group) Inhibited acetylcholine = rats were slow and made errors – (Second group) Inhibited physostigmine = rats were fastest – (Third group) Control = average speed (between the first and second group) • Conclusion: Acetylcholine is important in creating memory • Experiment was well designed, but it is unclear how much this relates to human physiology
  11. 11. Drugs • Drugs can simulate a certain neurotransmitter – When there is not enough of the neurotransmitter – When the site needs to be blocked
  12. 12. Brain & Behavior • Brain is the command center of activity • Case studies of brain damage help understand how the brain affects behavior – Often longitudinal studies (carried out over a long period of time) to see short-term and long-term affects of damage
  13. 13. Phineas Gage • Famous case study of brain damage and behavior – Phineas Gage was studied by Dr. John Harlow • Metal pole through skull (but still managed to survive???) • Ruined the balance between his intellect and his emotional control – Impatient, indulgent, profane, agitated, vulgar • Shows that the brain affects personality and social behaviors
  14. 14. Localization of Brain Function • Paul Broca (1861) found people with damage to the left frontal lobe couldn’t understand or make grammatically complex sentences • Broca’s aphasia: Problems producing speech, but still able to understand it – Famous patient called Tan because that’s the only word he could say
  15. 15. Localization of Brain Function • Carl Wernicke (1874) found area of brain crucial for language comprehension – Described as left posterior superior temporal gyrus • Wernicke’s aphasia: Patients could produce speech, but could not understand it
  16. 16. Localization of Brain Function • Language processing is localized – Meaning it is possible to trace the origin of the behavior to a specific part of the brain • Desire to map out brains functions • Localization doesn’t explain all human behavior, but it’s a start!
  17. 17. Robert Heath (1950s) • Found that electrically stimulating parts of the brain caused pleasure in patients with depression • Patients could press the button themselves to experience the pleasure • Patient B-19 pressed it 1500 times in 3 hours – Had to be disconnected despite protests
  18. 18. Dopamine & Serotonin • Dopamine produces desire • Serotonin promotes satiety and inhibition • All drugs increase production of dopamine and reduce production of serotonin • Both D&P play central roles in feelings produced by drugs like cocaine and nicotine • James Olds: Rats would walk over electrified grids to get to a lever that would stimulate the pleasure centers in their brains
  19. 19. Technology in Brain Research • Allows researchers to see where specific brain processes take place (localization) • Invasive techniques: removing/scarring brain tissue in order to study behavioral changes to compare the effect • Raise ethical concerns (DUH!) – Can’t undo it – Can’t foresee the potential harm – Hurting poor little defenseless animals!!!!!!
  20. 20. EEG (Electoencephalogram) • Often thought of as recording “brain waves” • Registers patterns of voltage change in the brain • Provides limited information – Cannot reveal what is happening in deeper brain regions – Can’t show the actual functioning of the brain
  21. 21. PET (Positron Emission Topography) • Monitors glucose metabolism in the brain • Used to diagnose abnormalities – i.e. tumors, Alzheimer’s progression, comparisons in sexes or disorders • Can record ongoing activity in the brain such as thinking
  22. 22. fMRI (Functional Magnetic Resonance Imaging) • 3D pictures of the brain structures using magnetic fields and radio waves • Shows brain activity and indicates which areas are active when engaged in a behavior • Higher resolution than PET scans • Easier to carry out than PET scans • Used super frequently today
  23. 23. Brain Plasticity • Brain can change as a response to environmental input – Demonstrated by Hubel and Wiesel (1965) • Brain plasticity: brain’s ability to rearrange connections between neurons – Changes that occur in the structure of the brain as a result of learning or experience • More stimulation and learning opportunities = denser neural connections
  24. 24. Dendritic Branching • When we learn something new the neurons connect to create a new trace in the brain • This is called Dendritic branching – Dendrites of the neurons grow in numbers and connect with other neurons
  25. 25. Rosenzweig & Bennett (1972) • Enriched environments vs. deprived environments & their effects on rats – Enriched = toys – Deprived = no toys • Enriched environment created thicker cortex and heavier frontal lobe in rats • Rat + toys + other rat friends = biggest growth in cortical thickness
  26. 26. Richard Davidson (2004) • Meditation of Buddhist monks and 10 volunteers • Monks and 2 volunteers had an increase in gamma waves during meditation – Gamma waves = higher reasoning faculties • After meditating for 10,000+ hours, the monks did not go back to normal gamma wave production afterwards • Therefore meditation can have long-term effects and the brain adapts to stimulation
  27. 27. Mirror Neurons • People can learn by observing others and imitating their actions • Mirror neurons fire when someone performs an action or when someone else performs the same action – May play a vital role in learning from and empathizing with someone • It “mirrors” the behavior of another
  28. 28. Gallese et al. (1996) • Could hear crackle of electrical signal caused by activated neurons • Monkey’s neurons crackled when it reached for a peanut to eat • Heard crackling noise again when researcher reached for a peanut to eat • Monkey’s brain acted as though the monkey had carried out the behavior just because it saw someone else carry out the behavior
  29. 29. Marco Iacoboni (2004) • Tested mirror neurons in humans • Supported Gallese’s findings • Observing a happy face activates pleasure centers in the brain • Could explain how we “feel” the hit a football player feels when they get tackled • Mirror Ns may have evolved to make us capable of understanding/interacting with others
  30. 30. Endocrine System • Hormones affect behavior too • Produced by the glands that make up the endocrine system
  31. 31. Hormones & their Functions Hormone Glands Function Adrenaline Adrenals •Fight or flight response •Arousal Melatonin Pineal •Regulation of sleep Testosterone and Oestrogen Gonads •Development •Emotion Oxytocin Pituitary Hypothalamus •Mother-child attachment
  32. 32. Oxytocin • Induces labour contractions and lactation • Released with touches and hugs – Bond between mother & child, and lovers • Called “the love hormone” • Affects fear regulation in brain; increases trust and generosity
  33. 33. Melatonin • Researchers study melatonin in hopes of helping insomnia and jet lag • Production of melatonin is stimulated by darkness and inhibited by light • Levels peak in the middle of the night • Earlier onset of darkness in winter makes us feel tired earlier • Melatonin pills may help with falling asleep
  34. 34. Seasonal Affective Disorder (SAD) • Rosenthal (1987) • Subcategory of depression with sleepiness and lethargy • Winter darkness disrupts circadian rhythm in people (biological clock) which leads to depression • Exposure to sunlight and bright light may improve symptoms