Functional Magnetic Resonance Imaging (fMRI) for the Study of Response Inhibition, and Face and Linguistic Processing in Autism

Fifteen adult outpatients with high functioning autism or Asperger's Syndrome will be
recruited. Fifteen healthy volunteers matched for age and IQ will also be recruited.
Participants will undergo an fMRI scan. During the scan they will perform a task. The
paradigm is designed to test control inhibition, face processing and language. Therefore, it
includes a go-no go test, a face emotion discrimination test and a linguistic sound. The
subjects are shown a series of faces with happy or sad expressions in random order. Each
face presentation is accompanied by either a standard or variant sound. The sound stimulus
is the English phoneme /oe/. The variant sound was created by raising the frequency of the
standard sound by 20%. The task consists of four blocks. During each block the subjects are
asked to press a button when they see a happy or sad face depending on the block. Each
block consists of 96 trials lasting 2 seconds and an initial and final fixation period of 40
sec. For each trial the target image is projected for 500 ms. There is 1250 ms fixation
time allowed for response and 250 ms for jitter. Twenty-four of the 96 trials are no go
trials and 16/96 are sound oddball trials. The oddball is at least two trials apart
(between two variant sounds there are at least two standard sounds). There are 24 faces
displayed in total, 12 female and 12 male. Faces switch every 16 trials. Face genders are
balanced. The faces were selected with over 80% congruency except for two faces with
congruency of over 72%. The correlation between sound (2 conditions: standard versus
variant) and target condition (go-no go) is zero. The task was piloted on healthy controls
and autistic adults. All subjects performed well.