Objectives: Our goal was to further our understanding of the nature of hypo-connectivity in autism, and specifically its correlation with (1) specific frequency bands, (2) task demands, and (3) distance between the cortical regions.
Methods: We studied 8 high functioning adults with autism and 8 age and gender matched healthy controls (6 of 8 were also verbal IQ matched) using whole head Magnetoencephalography (MEG). We looked at three conditions – fixation with i) no immediate associated task (‘fixation’), and in preparation for ii) a saccade or iii) an antisaccade task. For each subject and condition, we analyzed 64 seconds of concatenated data for coherence in the delta, theta and alpha frequency bands.
Results: Significant coherence reduction in autism was observed during ‘fixation’ and antisaccade preparation (p<0.02), but not during prosaccade preparation, in the delta band. A tendency for coherence reduction was also found in theta band during antisaccade preparation (p<.07), and in the alpha band (p<.07) during ‘fixation’. The observed differences tended to be more pronounced for longer distances, ensuring this is not a volume conductance effect. The regions driving the differences were mostly posterior (mainly occipital).
Conclusions: These observations support the hypothesis of weaker long-range cortical functional connectivity in autism. Our thus far preliminary findings indicate that weaker functional connectivity seems to be band, task, and region dependent.