fMRI study

• 6 normal, 6 HFA (each 5 male, 1 female)
   ADI-R diagnosis
• 10 trials: 30s fixation, 60s task, 30s fixation
• EPI at 1.5T, TR=3s, TE=40ms, 90º flip
  coronal 7mm skip 1, 20cm FOV, 64x64 matrix
• Two analyses:
  (1) task. vs. fixation to map functional regions
  (2) attend-left vs. attend right, within these regions

Last year I told you about our preliminary findings looking at this same task with fMRI.

We've now completed that fMRI study, using six subjects with high-functioning autism and six controls matched for sex and age range.

Given the relative slowness of the haemodynamic effect that we're observing in fMRI, we spaced out the targets so that there were only a few within each 60-second block. We ran ten of these blocks, with rest breaks in between, and used an optical switch to record behavioural responses and an infrared eye tracking system to monitor fixation.

We collected echo-planar images at 1.5 Tesla, in 7mm slices. We applied automated rotational and translational motion correction in k-space using the DART algorithm, and then we applied two separate functional analyses: first, task versus fixation, and then within the task blocks, attend-left versus attend-right.

`Functional Anatomy of Compensatory Processing in Autistic Attention: Complementary Roles of Selection and Suppression', Matthew Belmonte, 1 November 2002