Neural Correlates

• Measurements of the structure or function of the brain that correlate with symptoms of schizophrenia
• There are neural correlates of positive symptoms and negative symptoms
• EG lower activation levels in the superior temporal gyrus and anterior cingulate gyrus have been found in those experiencing auditory hallucinations
• The Dopamine hypothesis

  Hyperdopaminergia - Positive symptoms of schizophrenia are caused by higher levels of dopamine in the subcortical areas/sub cortex (limbic systems eg amygdala and hypothalamus)

  Hypodopaminergia - Revised theory - both high and low levels of dopamine in different brain regions are involved in schizophrenia, eg low levels in the pre-frontal cortex
• Dopamine Hypothesis

  Schizophrenics have abnormally high D2 receptors on receiving neurons, resulting in more dopamine binding and therefore more neurons firing (EG excess D2 receptors in Broca’s area associated with auditory hallucinations)

  Neurons that transmit dopamine fire too easily or too often
• Strength - Animal studies

  Researchers induced dopamine depletion in the prefrontal cortex in rats

  Resulted in cognitive impairment that the researchers were able to reverse using olanzapine - an atypical antipsychotic drug thought to have beneficial effects on negative symptoms in humans
• Strength - Neural correlates on negative symptoms

  Ventral striatum is involved in the anticipation of a reward

  Avolition = loss of motivation / goal oriented behaviour

  Juckel et al (2006) found a negative correlation between activity levels in the ventral striatum and the severity of negative symptoms

  As activity in the ventral striatum decreases, avolition increases

  Ventral striatum activity is a neural correlate of negative symptoms