Amygdala dysfunction 10

• What is the amygdala

  Part of the limbus system

  Fear and emotion processing

  Implicated in memory processing

  Connections to the prefrontal cortex, hippocampus, hypothalamus and other areas.
• Nordahl et al 2012

  Found that from 2 years of age, there is larger growth in amygdala volume in children with ASD (6-9%).
• Amygdala development

  By late adolescence / early childhood there is no difference in amygdala volume between those with / without ASD.

  The growth in volume occurs earlier in children with ASD & this may result in abnormalities in the neutral organisation of the amygdala and damage its functioning.
• Baron-Cohen 2000

  As the amygdala has neural connections with the frontal cortex, abnormal development of the amygdala in childhood is a causal factor involved in social & behavioural deficits.

  Therefore, those with ASD have difficulties understanding expression of emotions.

  He investigated this using the eye task.
• Baron-Cohen eye task

  Procedures:

  Adults with ASD matched with controls of adults without ASD.

  Presented with photos of eyes of people making different facial expressions. Asked to identify the expression shown.

  Brain activity measured in an MRI scanner during task.

  Findings:

  Those with ASD performed significantly worse.

  Left amygdala not activated in those with ASD but strongly activated in controls.

  Conclusion:

  Left amygdala involved when inferring emotional state from facial expressions. This function impaired in those with ASD.
• Applying methods of modifying

  Intranasal oxytocin has been found to increase oxytocin levels in areas such as the limbic system, where the amygdala is located.

  Some studies have shown that when people with ASD take intranasal oxytocin, they show improved scores on tests of social behaviours.
• Strengths of the amygdala dysfunction explanation

  Scientific

  Supported by brain scan evidence (Baron-Cohen)

  Deterministic
• Weaknesses of the amygdala dysfunction explanation

  Ignores nurture

  Incomplete?

  Doesn’t explain repetitive behaviours

  Deterministic