• Correlations between regional cerebral metabolic rates for glucose (rCmrglc), determined by positron emission tomography using18F-2-deoxy-2-fluoro-D-glucose, provide a measure of the functional associations between brain regions. We compared correlations between ratios of resting rCmrglc to global brain metabolism from 14 healthy autistic men (ages, 18 to 39 years) with those from 14 matched control subjects. The autistic group showed significantly fewer large positive correlations between frontal and parietal regions, particularly those with the left inferior frontal region and its right hemispheric homologue, and significantly lower correlations of the thalamus, caudate nucleus, lenticular nucleus, and insula with frontal and parietal regions, with many correlations negative in the autistic group that were positive in the control group. These results are compatible with functionally impaired interactions between frontal/parietal regions and the neostriatum and thalamus, regions that subserve directed attention.