fMRI investigation of decision making, temporal foresight & reward evaluation in Asperger's syndrome

Background:

There is evidence that people with autistic spectrum disorder (ASD) have deficits in cognitive flexibility, planning & response to reward. Competent planning is crucial to decision making, and involves inter-temporal bridging - making future choices based on experience and outcome evaluations and understanding future consequences of one’s actions.

Objectives:

Investigate brain function in individuals with Asperger’s and healthy Controls during a gambling task that measures outcome evaluation and reward-related inter-temporal decision making.

Methods:

Nine individuals with Asperger’s and twenty matched Controls completed an event-related adaptation of the The Iowa Gambling Task on a 3T magnetic resonance imaging (MRI) scanner. The task involves choosing between card decks that result in high immediate monetary gain, but larger future loss (“risky”: long-term loss), or low immediate gain, with larger final reward (“safe”: long-term gain). Data were analysed using non-parametric image analysis (XBAM).

Results: In Controls, preference for “safe” choices, reflecting forward thinking and inter-temporal competence, when contrasted with disadvantageous risky choices, elicited activation in ventromedial prefrontal, anterior cingulate, and parietal cortices and mid-cerebellum. Monetary wins, compared to losses, showed increased activation in the caudate, anterior cingulate and cerebellar hemispheres, whilst losses compared to wins showed increased activation in the bilateral inferior prefrontal, insular and cingulate cortices.

In individuals with Asperger’s, preliminary analyses show abnormal brain activation in the neural networks activated in controls during “safe”decisions, and in relation to reward. Detailed results will be provided at the conference.

Conclusions:

We hypothesise that individuals with Asperger’s will have; i) reduced number of reflective, advantageous choices, ii) reduced dorsolateral and orbital prefrontal brain activation during these choices & iii) blunted brain activation response to both positive and negative reward feedback. Final analyses on a larger sample of 20 patients will be presented at the conference and implications of the findings will be discussed.