BA

• • Everything psychological has a biological basis 
  • Our biology is determined by genes and evolution 
  • To explore the mind you have to explore the physical brain 
• The role of genes

  • Genes are sections of DNA with instructions to make enzymes and hormones 
  • Genes are also responsible for the genetic code for the production and adequate functioning of the CNS structures like the brain and spinal cord 
  • Since behaviour is determined by adequate functioning of the CNS and neurotransmitters, behaviour is directly impacted by genes 
  • If problems occur in the genes, problems will occur in the proper functioning of an adequate CNS leading to issues in behaviour 
• The role of genes

  Allele- different versions of the same gene in different people 

  Researchers have found that certain genes have led to a vulnerability to certain behaviours for example OCD, these genes that lead to a vulnerability are known as candidate genes for OCD it is the 5-HTT gene- which leads to the lower level of serotonin found in those with OCD
• The influence of the brain

  • Controls day to day behaviour and responsible for our thoughts, emotions and sensations for example the cerebral cortex is responsible for high order functions like decision making and language 
  • If there is damage in the brain this leads to damages in thinking ability which leads to issues in behaviour 
• The role of neurotransmitters

  • Brain is full of neurons that communicate through chemicals + electrical impulses 
  • Neurotransmitters: chemical messengers that travel back and forth the synapse delivering messages between neurons e.g postsynaptic + presynaptic neuron 
  • Upon arrival of electrical impulse, NTs diffuse across synapse- (gap between two neurons) + pass info to next neuron by binding to it 
  • Different NTs will increase + decrease likelihood neurons will fire e.g excitatory neuron (dopamine) will increase the likelihood whereas inhibitory neuron (serotonin) will decrease likelihood  
• The influence of evolution

  • First there is the random mutation of a gene which leads to adaptive characteristics and makes us better suited to survive 
  • Then through natural selection those with adaptive characteristics genetically pass on the traits which increased survival in that specific environment 
  • Thus these traits are carried on through each successive generation and leads to evolution which affects our behaviour today
  • The behaviours that were adaptive for our ancestors are now present in all of us today 
• Supporting evidence for genetic explanations

  • McGuffin Twin study
  • Conducted a study on depression in twins in both monozygotic and dizygotic twins 
  • He found a 46% concordance rate in MZ twins and a 20% concordance rate in DZ twins 
  • This shows that the higher the shared proportion of genes increases the amount of shared characteristics/behaviour when comparing MZ twins to DZ twins 
  • This shows that genes do have an impact on behaviours like depression 
  • Increasing the validity of the bio approach as an explanation for behaviour
• PA

  • Understanding of the effect of neurotransmitters on beh provided by the biological approach allows for the development of drugs from researchers to decrease abnormal beh
  • E.g Depression is a result of low levels of serotonin which has lead to the development of antidepressants like SSRIs which increase serotonin levels 
  • Giltin, found antidepressants have reduced 65-75% of symptoms in people suffering with depression thus improving lives 
  • Since researchers rely on assumptions of the bio app to create these solutions + they are effective in turn this increases validity of bio approach
• Biological explanations are reductionist 

  • This approach does not take into account the stress diathesis model which argues that genes only make you vulnerable to behaviour, but you need a certain environmental trigger like a traumatic life event to actually express the behaviour 
  • This is a problem as the BA reduces explanations of behaviour purely to genes and biological factors
  • But it does not consider the relationship between genes and the environment 
  • Thus the BA can be seen as an incomplete explanation of behaviour reducing the validity of the BA 
• Nature + nurture cannot be easily separated 

  • Twin studies reliance on gene for the exp of high CR in MZ twins leads to questionable validity 
  • Fails to recognise the influence of environment on CR
  • High CR found in MZ twins could be not just because of proportion of genes shared could be because they look the same so get treated the same 
  • Cannot be sure that the high CR is purely due to genes or environment is hard to separate effects of nature vs nurture 
  • Question validity of conclusions made in twin studies in turn questioning validity on which assumptions it relies on
  • Reduces validity