Autism: Biological explanation (amygdala)

Question 1

What is the amygdala? (brain info, and role)

Answer 1

The amygdala is a collection of neuron cell bodies (nuclei) in each of the brain’s hemispheres. It is a highly networked structure, densely interconnected with other regions.

The amygdala has a powerful influence through these connections on behaviours associated with motivation, emotion and social interaction.

Question 2

According to Nordahl et al. (2012), how does the amygdala development vary?

Answer 2

• Amygdala of children with ASD is 6-9% larger from two years old than in children without it.
• As children with ASD get older, volume growth stalls.
• But growth continues in children without ASD, so by late adolescence there is no difference in volume between the two.

Question 3

Why may the difference (in ASD it grows quicker then slows) in amygdala development explain impairments?

Answer 3

This early development in ASD may be partly responsible for any abnormal neural organisation and impaired functioning of the amygdala.

Question 4

What is the link between frontal cortex and amygdala? (Baron-Cohen et al, 2000)

Answer 4

Baron-Cohen et al. (2000) applied this idea to ASD:

Amygdala is connected to frontal/prefrontal cortex (major role in processing social information).

• Abnormal amygdala development affects the operation of these parts of the brain.
• Key because ASD (e.g. impairments of social-emotional reciprocity).

Question 5

What is the role of the amygdala in impaired social processing? (Baron-Cohen et al, 1999)

Answer 5

Baron-Cohen et al. (1999) showed that this is due to amygdala dysfunction impairing social processing:

• Gave participants the ‘eyes test’ (photos of people making facial expressions, showing just the eye areas).
• People with ASD found it hard to guess if it was concerned or unconcerned.
• fMRI scans showed that, relative to controls, people with ASD had under active left amygdala.

Question 6

What is a strength of the biological explanation? (hint: support from case study of SM!)

Answer 6

A strength of amygdala dysfunction theory is support from clinical studies.

Kennedy et al. (2009) studied ‘SM’ who did not have ASD, but a rare genetic disorder impaired her amygdala function.
Her preferred personal space distance was about half of that for matched control participants.

This finding shows that amygdala dysfunction is associated with social deficits that are similar to those found in ASD.

Question 7

What is a weakness of the biological explanation? (hint: amygdala and autism indirectly linked with…)

Answer 7

A weakness is that the ASD-amygdala dysfunction link may be indirect.

People with amygdala damage cannot process anxiety-related information normally, so social functioning is impaired.
White et al. (2009) suggest there may be a link between amygdala dysfunction and social behaviour deficits that are due to abnormal processing of anxiety.

This shows that the role of the amygdala in ASD is more complex than the conventional dysfunction explanation suggests.

Question 8

What is an application of the biological explanation? (hint: drug treatment maybe?!)

Answer 8

The dysfunction explanation offers a potential target for treatment.

A drug treatment that corrects amygdala functioning is possible. Also, if amygdala dysfunction is reliably linked to ASD, it could lead to earlier diagnosis.

This could help shorten the ‘diagnostic journey’, the drawn-out and highly stressful process many families go through to get a diagnosis.