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postheadericon Biological

Friday, September 02, 2011 | | Edit Page
Biological Psychology Biological Psychology The biological approach is all about finding biological correlates of behavior. A biological correlate is when some neurotransmitter, hormone, brain area, or gene is correlated with a behavior. So if extra testerone is associated with increased aggression, testesterone is considered the biological correlate of the aggression.

Homer below illustrates the biological correlate of his intelligence (and stupidity).


Afterwards


Principles

  • Behavior is biologically determined by physiological processes such as the nervous system neurotransmitters (e.g. serotonin) and the endocrine system (hormones e.g. adrenalin increases heart rate and fight or flight response)
    • "All that is psychological is first physiological" (Sperry)
  • Patterns of behavior can be inherited through genetics
    • Related to evolutionary psychology
  • The study of animals can inform our understanding of human behavior
    • Psychologists use rats and monkeys for a lot of research but the results cannot always be generalized to humans

Principles of the Biological Level in Theories and Research

  • Localization of function (Broca's Area in speech production) discovered through post mortem analysis of brains
  • Genetic predisposition of schizophrenia using correlational  twin research (Gottesman and Shields, 1976) PDF
  • The dopamine hypothesis of schizophrenia - amphetamines increase positive symptoms of schizophrenia in normal patients and increases positive symptoms further in schizophrenic patients (Laruelle et al., 1996) PDF
  • The monoamine hypothesis of depression - serotonin is the biological correlate - less makes depressed :(

Research Methods

  • Lab Experiments
  • Neuroimaging allow you to find brain regions (biological correlates) of behavior
    • PET
    • fMRI
  • Correlational studies allow you to test the role of genetics vs. environment on behavior
    • Twin studies - twins reared apart to test the effect of genetic vs. environment on their behavior
      • Any differences found between twins reared apart are considered environmental
    • Family studies
  • Lesion studies allow you to find biological correlates of behavior, we assume the missing behavior and damaged area are related
    • Phineas Gage
    • HM
    • Clive Wearing

Ethical Considerations

Physiology and Behaviour

Localization of Function

  • Broca's Area - Involved in speech production
  • Wernicke's Area - Involved in speech comprehension
    • Wernicke's aphasia results in 'word salad' with fluent speech
    • Patients can produce speech with proper grammar but sentences are nonsensicle

This is an example of word salad from Boston Legal, the closing statement is very fluid but makes no sense

  • Split brain studies make the two hemispheres unable to communicate after severing the corpus callosum

Here's a clip from House showing the effects of split brain surgery


Effects of Neurotransmission on Behavior

  • Dopamine
    • Voluntary movement
    • Learning
    • Pleasure
  • Serotonin
    • Sleep
    • Arousal Levels
    • Emotion
      • Happiness
    • Monks hallucinated after 48 hours of no food or water - linked to increased serotonin levels (Kasamatsu & Hirai, 1999)
    • Amount of serotonin can determine sexuality in mice (Liu et al., 2011)

Now for some videos of the rats in Liu's study.

Normal serotonin male chooses a female over a male - straight rat


Low serotonin male mounts a male - gay rat?


Low serotonin male mounts both male and female - bisexual rat?


Functions of Two Hormones on Behavior

Effects of Environment on Physiological Processes

  • Brain plasticity - ability to rewire connections between neurons
  • Enriching environment leads to increased cortical thickness in rats compared to boring environment (Rosenzweig & Bennett, 1972)
  • Environmental stressors at work can increase our susceptibility to disease (e.g. heart disease)
    • Do Google employees have this problem? Check out this video Flash Video of the work life at Google.
  • Eating disorders can disrupt the menstrual cycle - can be considered an evolutionary mechanism to prevent an unprepared female from conceiving a child
  • Sleep deprivation in rats causes increased metabolism (210-270%) despite increased food intake and for most rats eventual death (Rechtschaffen & Bergman, 1995) PDF
  • Menstrual Synchronicity PDF

Interaction between Cognition and Physiology in Terms of Behavior

  • Meditation produces gamma waves found using a PET scan with monks (Davidson, 2004)
    • Meditation (cognition) can have a permanent change on physiology (the gamma waves) if practiced enough
    • Control participants gamma wave activity returned to normal after they stopped meditation

Brain Imaging Techniques

  • EEG - records brain waves
    • Cannot show what is happening in deeper brain regions
    • Cannot show actual functioning of brain regions
  • PET - monitors glucose metabolism in brain via injection of radioactive glucose
    • Can record ongoing activity like thinking during a task
  • fMRI - provides 3D image of brain
    • Easier to carry out compared to PET
    • Higher resolution than PET
    • Cannot record ongoing activity - just snapshots
Evaluation
  • fMRI scanners are unnatural environments for cognition - ecological validity
  • fMRI machines are very noisy so you need to use special headphones for auditory experiments
  • Colors in images may exaggerate activity in brain regions
  • fMRI may not be sophisticated enough to detect subtle brain activity so activity that is important/interesting may not be detected
  • Brain areas activate for various reasons because the brain is highly interconnected so you cannot conclude that just because the amygdala is activated the patient is experiencing fear

Genetics and Behavior

Extent of Genetic Inheritance on Behavior

  • Huntington's - Only neurodegenerative disease with a 100% genetic cause
  • Schizophrenia - DISC1 implicated (Hennah et al., 2006)
    • Diathesis stress model - environment and genetics
  • Affective Disorders - Short and Long Serotonin Transporter Genes implicated in disposition to depression (Caspi et al., 2003) PDF and in some cases suicide (Du et al., 1999) PDF
    • Transporter gene linked to happiness in teenagers (De Neve)
  • Diathesis stress model is most accepted
  • Serotonin hypothesis of depression vs. neurogenesis hypothesis
Intelligence and Genetics
  • Both genetics and environment play crucial role
    • Poverty tends to correlate with low IQ
  • Meta-analysis of 111 studies found highest correlation for IQ was kinship (Bouchard & McGue, 1981)
  • Minnesota Twin Study (Bouchard et al., 1990) PDF
    • MZ twins raised together compared to MZ twins raised apart longitudinal study
    • Estimate that heritability accounts for about 70% of intelligence
    • Criticism
      • Media coverage to recruit participants - possible sample bias
      • Ethical concerns about how he reunited the twins who were reared apart
      • No control over how often the twins reared apart visited each other prior to study
      • Equal environment assumption - cannot assume twins raised together experience same environments (e.g. treatment from parents, experience with friends and peers in school and at home)
    • Adoption studies (Scarr & Weinberg, 1977; Horn et al., 1979)
      • No significant difference found in correlations despite adoptive parents being wealthy, white and with high IQ and adopted children being from poor backgrounds

Ethical Considerations for Research into Genetic Influences

  • Undue stress on patients being tested for Neurodegenerative diseases Alzheimer's, Parkinson's but less with Huntington's because of reliability of prognosis)
  • Parents can feel responsible for fate of the child
  • Patient may feel less responsible for their disease and make less of an effort to recover, instead relying on medications to do the psychological work

Evolutionary Explanation of Behavior: Disgust

  • Promotes survival by avoiding rotting foods that could make us sick and threaten our survival (Fessler, 2006) PDF
  • Confirmed by online survey that found participants had the strongest disgust reaction to stimuli which threatened the immune system (Curtis et al., 2004) PDF
  • Has also been related to biological preparedness and phobias because animals that elicit a disgust response can be poisonous and avoiding these creatures because they evoke disgust further promotes survival

Evolutionary Explanation of Behavior: Altruism

  • Altruism is when you perform a behavior for someone (to increase their survival) at a cost to yourself (like getting hurt) without any clear benefit to yourself
  • Having altruistic individuals in your group can strengthen the group because you have individuals willing to sacrifice themselves to benefit the survival of the group
  • Do human infants and chimpanzees to see if they help given the opportunity (Warneken and Tomasello, 2006) PDF
  • Warneken and Tomasello found that humans and chimps both help when they understand the intention of the person who needs help
  • Their results suggest altruism has an evolutionary basis

Here are some clips from the Warneken and Tomasello (2006) study



Evaluation of Evolutionary Arguments
  • Testing evolutionary theories of behavior is empirically difficult so researchers may be led astray by confirmation bias
  • We know little, if anything, about Homo sapiens’ behavior - it is purely speculative
  • Disregard the role of culture in shaping behavior

Additional Resources

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