Color mapping of middle-latency somatosensory evoked potentials in autistic mentally retarded children

Middle-latency somatosensory evoked potentials (MLSEPs) from the median nerve were recorded from 19 scalp electrodes in a group of 9 male autistic mentally retarded children and compared with those obtained from 7 age-matched normal controls. Autistic patients showed a more frontally distributed N60, after stimulation of both sides, a lower amplitude of the parietally distributed P100 and, at approximately 140 ms, a prefrontal area of difference only with Stimulation of the right median nerve. This study demonstrates the existence of subtle changes in the MLSEPs in autistic mentally retarded subjects, which are different from those observed in other developmental disorders; they involve both frontal and parietal areas and are more evident after stimulation of the right median nerve, as a probable consequence of altered left/right hemisphere relationships.