Background Fine engine skill impairments are common in autism spectrum disorder (ASD) significantly affecting quality of life. alterations are associated with motor impairment in ASD. Methods Sixty right-handed neurotypical adult men aged 18 to 45 years and 60 right-handed age- and sex-matched subjects diagnosed with ASD underwent fine motor skill assessment and scanning with diffusion tensor imaging (DTI). The streamlines of the hand region connecting S1-M1 of the motor-sensory homunculus were virtually dissected using TrackVis and diffusion properties were extracted. The face/tongue region connections were used as control tracts. Results The ASD group displayed lower motor performances and altered DTI measurements of the hand-region connection. Behavioral performance correlated with hand-region DTI measures in both groups but not with the face/tongue connections indicating anatomical specificity. There was a left-hemisphere association of motor ability in the control group and an atypical rightward shift in the ASD group. Conclusions These findings suggest that direct conversation between S1 and M1 may contribute to the human ability to precisely interact with and manipulate the environment. Because electrophysiological evidence indicates that these connections may underpin long-term potentiation in M1 our findings may lead to novel therapeutic treatments for motor skill disorders. < .025. Diffusion Tensor Imaging Data Acquisition and Preprocessing Participants were scanned at the Centre for Neuroimaging Sciences Institute of Psychiatry Psychology and Neuroscience King’s College London and the Department of Radiology University of Cambridge using two identical 3T GE Signa System scanners (General Electric Milwaukee WI). A total of 60 contiguous slices were acquired using a sequence fully optimized for diffusion tensor imaging (DTI) providing isotropic (2.4 × 2.4 × 2.4 mm) resolution and whole head coverage. There were 32 diffusion-weighted volume directions and 6 nondiffusion weighted volumes. The diffusion weighting was equal to a value of 1300 s/mm2. DTI digesting was performed using Explore DTI (http://www.exploredti.com). The data were corrected for eddy current distortion and subject motion and the matrix was accordingly reoriented (27). The tensor model was fitted using a nonlinear least square fitted procedure (28). DTI scalar maps including fractional anisotropy mean diffusivity and perpendicular diffusivity were calculated and exported. Whole-brain tractography was performed using an Euler-like streamline propagation algorithm with a step-size of 1 1 mm fractional anisotropy threshold of 0.2 and an angle threshold of 35° (29). The whole-brain Exatecan mesylate tractography was imported into TrackVis for virtual dissections (30). Tractography and Virtual Dissections Exatecan mesylate Virtual in vivo dissections of the tracts of interest for the left and right hemispheres were performed using TrackVis. The connections were dissected in regions corresponding to the hand face/tongue and foot regions of the motor-sensory homunculus (Physique 1). The foot and face/tongue region connections were dissected as control tracts (Product). The dissector was blinded to subject identity and diagnosis. Thirty-one data units (25.8%) were reversed round the midline to ensure blindness to side. All dissections were completed after ensuring intrarater reliability. This was tested with Exatecan mesylate the use of 10 subjects from the present study dissected twice by the same dissector. Reliability was tested using a two-way mixed intraclass correlation coefficient (ICC) (31). For the hand and face/tongue tracts the ICC for CIT single steps reached >0.90 (32). We found that the foot connections consisted of only one or two individual streamlines and were not present in a number of participants. Diffusion properties for the foot streamlines did not reach >0.90 on the ICC and were therefore excluded from all further Exatecan mesylate analyses. For each tract fractional anisotropy perpendicular diffusivity and mean diffusivity were calculated. Alterations in these steps reflect microstructural differences that may include altered axonal Exatecan mesylate integrity compactness of fibers bundles and myelination (33). Fractional anisotropy shows the amount of directionality of drinking water movement within a voxel. Although delicate to microstructural differences fractional anisotropy will not provide highly.