The leading model of disrupted brain development in ASD focuses upon disrupted communication across disparate brain regions. However, this view cannot be adequately tested as the brain imaging tool of choice, functional magnetic resonance imaging (fMRI) cannot be applied to all children with ASD as they move their heads excessively confounding results and/or are afraid to go into the MR scanner. Thus, it is necessary to develop alternate imaging tools that will measure the same information as fMRI but without the constraints of head-motion and fear. Near-infrared spectroscopy (NIRS) is one such tool that has been extensively used in infants to examine brain activation. Measurement includes wearing a net of optical sensors on the head (e.g., like a shower cap) – this has no safety risks and children can move as the net moves with head and thus measurement is not confounded. This project aims to test the viability of NIRS for use with 9-12 year old high-functioning children with ASD in two studies: Aim 1 is a validation study that will show that NIRS yields the same well known finding in ASD – reduced activation in response to cognitive load in frontal and parietal regions. Aim 2 will test a new hypothesis that functional communication differences in ASD depend upon cognitive state (i.e., whether children are resting or responding to cognitive challenge). As control children respond to the challenge, communication between frontal and parietal regions and across the two hemispheres in are expected to increase in each lobe as compared to when they were at rest. Children with ASD are expected not to show this change or show it to a lesser extent. This finding will reveal that dynamic engagement of disparate regions in response to external demands is inefficient in children with ASD. The significance of this work is two-fold: 1) it will provide an alternate to fMRI that can be used with lower-functioning and younger children, both with ASD and controls; and 2) state-related change in functional communication could be a potential biomarker for children at risk for ASD.