bio psych

• Brain Structure


  • Frontal lobe - planning and organising
  • Parietal lobe - sensory info and visual-spatial processing
  • Occipital lobe - visual info processing
  • Temporal lobe - recognising and processing sound
• Prefrontal cortex


  Develops late (mid 20s), executive functions
• Corpus callosum


  Joins 2 hemispheres of brain, massive bundle of neurons that allows communication between hemispheres
• Limbic system


  • Thalamus - info from 5 senses, key role in emotions
  • Amygdala - emotions such as fear and anger, trigger fight or flight response
  • Hippocampus - key role in memory (converting STM to LTM)
  • Hypothalamus - regulates body functions e.g. release of hormones
• Structure of neurons


  • Axon - sends impulses to dendrites
  • Dendrites - receive impulses from the axon ('messages')
  • Cell body - contains nucleus (and mitochondria)
• The CNS includes the spinal cord and the brain.
• Nucleus


  Contains genetic material
• Axon hillock


  Connects cell body to axon
• Myelin sheath


  Fatty deposit that insulates impulses
• Node of Ranvier


  Gap between adjacent myelin sheaths
• Synapse


  Gap between neurons
• Synaptic function


  1. Action potential moves down presynaptic neuron

  2. Neurotransmitters released into synaptic cleft by endocytosis

  3. Neurotransmitters bind to receptors on postsynaptic neuron causing action potential

  4. Neurotransmitters taken up by reuptake processes - diffusion away from synaptic cleft and degradation by enzymes in synaptic cleft, then reuptake back into presynaptic neuron
• Neurotransmitters


  Chemical messengers that take information around the body
• Where neurotransmitters are released from

  • Neurons
  • Presynaptic neuron into synaptic cleft after action potential
• What neurotransmitters stimulate


  Stimulate the postsynaptic neuron and assist it in creating its own action potential
• Recreational drugs


  Increase dopamine levels in the ventral and nucleus accumbens
• Effects of recreational drugs

  1. Prolong and intensify the activity in the reward system

  2. Ensure that an increase in dopamine levels continues

  3. Cause post-synaptic neurons to keep firing

  4. Block pre-synaptic transporters so re-uptake is stopped

  5. Stop the action of enzymes so more dopamine is left in the synaptic cleft
• The effect of recreational drugs on the reward system is to increase the intensity and duration of the response
• Aim of Van den Oever et al. (2008) study

  To investigate changes in the molecular composition in the medial frontal cortex upon re-exposure to drug-associated cues
• Experimental procedure of Van den Oever et al. (2008) study

  1. Experimental group self-administered heroine and were exposed to audio-visual cues

  2. Control group self-administered sucrose solution

  3. Abstinence period of 21 days

  4. Extinction training in self-administration box for 21 days

  5. One group experienced drug-associated cues, one group was not exposed to drug-associated cues

  6. Rats were decapitated and brains were frozen and analysed by mass spectrometry
• VDO found behavioural evidence of relapse in the experimental group
• VDO found increased AMPA receptor levels in the experimental group compared to normal
• VDO concluded that heroine relapse changes the molecular composition and function of synapses
• VDO found that rats not injected with heroine did not show endocytosis and drug-seeking behaviour
• VDO concluded that the reduction of AMPA receptors is a result of being re-exposed to drug-associated cues
• Generalisability of the VDO


  • Crucial brain areas studied are similar to humans
  • Only used male rats, so not fully generalisable
• Reliability of the VDO

  • Used Wistar rats
  • Standardised procedures, high scientific credibility
• Validity of the VDO

  • Used control groups and controlled for extraneous variables
  • Could be considered reductionist