Neural correlates/ dopamine hypothesis

• Original dopamine hypothesis  

  Argued that schizophrenia was caused by excessive activity of dopamine  

  • This causes neurones to fire too often and transmit too many messages  
  • Suggested that this overload led to the many of the symptoms of schizophrenia 

  This is known as hyperdopaminergia - refers to high levels and activity of dopamine  
• Example of original dopamine hypothesis

  • Excess of dopamine receptors in Broca's area may be associated with poverty of speech or experience of auditory hallucinations 
• Updated version of dopamine hypothesis

  • Focuses on the role of low levels of dopamine and abnormal dopamine systems in the brain 
  • Particularly in the pre-frontal cortex 

  This is known as hypodopaminergia - refers to abnormally low levels and activity of dopamine  
• Example of updated dopamine hypothesis

  • Goldman-Rakic et al (2004)  
  • Low levels of dopamine - in the pre-frontal cortex (responsible for thinking and decision making) may play a role in in the negative symptoms of schizophrenia  
• Evidence for dopamine - 😊  

  • There is large support to the influence of dopamine on schizophrenia  
  • Curran et al (2004) - Amphetamines increase dopamine and worsen symptoms in people with schizophrenia even inducing symptoms in people without it  
  • Tauscher et al (2014) - antipsychotic drugs reduce dopamine activity and reduce the intensity of symptoms  
  • Some candidate genes also act on the production of dopamine and dopamine receptors  
  • This strongly suggests that dopamine is involved in soe of the symptoms pf schizophrenia  
• Glutamine - 🙁  

  • There is some evidence for the central role of other neurotransmitters like Glutamine  
  • McCutcheon (2020) - In post-mortem and live scanning studies conducted on schizophrenic individuals. They have been found to have raised levels of the neurotraumatic glutamine in several of their brain region 
  • Furthermore, serval candidate genes for schizophrenia are believed to be involved in glutamine production or processing  
  • This means that other neurotransmitters also play a role in schizophrenia