biological explanation

• parts of the brain related to theory?

  • thalamus, checking and cleaning behaviour (overactive= compulsion)
  • orbitofrontal cortex, alerts potential worries in environment (overactive= anxiety)
  • cingulate gyrus, connects orbitofrontal cortex to thalamus
  • basal ganglia nuclei, inhibit thalamus
  • globus pallidus, act as braking mechanism controlling thalamus activity
  • caudate nucleus, normal action= inhibit globus pallidus fibres
• Menzies (2007)?

  • found people suffering from OCD had a different amount of grey matter in orbitofrontal cortex to those without OCD. shows differences in brain structures
• Whiteside (2004)?

  • shows differences in brain functioning. cingulate gyrus, basal ganglia and orbitofrontal cortex are active when at rest compared to controls without OCD. become more active when OCD symptoms are stimulated and are no longer overactivated following drug treatment/CBT
• Salloway and Duffy (2002)?

  • PET scans of OCD patients had increased activity in pre frontal cortex. (credible)
• surgical lesioning? (evaluation)

  • successful treatment for OCD, cingulate gyrus undergoes surgical lesioning (connects thalamus with orbitofrontal cortex) suggesting OCD results from faulty feedback loop so breaking the loop can cure OCD
  • doesn't always work, Kireev (2013), found functions performed by cingulate gryus can be taken over by other areas in brain (reductionism)
• other weaknesses of explanation?

  • doesn't show cause and effect, so brain activity is a symptom not a cause
  • since they're just related it's difficult to determine whether brain activity alters thoughts or vice versa
  • not just biological? many people with OCD have no family history of it. Van Grootheest (2005), concordance rare in MZ is only 27-47% higher than DZ