Somatosensory discrimination: An intracranial event-related potential study of children with refractory epilepsy

The objective of this study was to determine if a prefrontal somatosensory mismatch response (sMMR) could be recorded in response to deviations in duration of somatosensory stimuli. Intracranial somatosensory event-related potentials were recorded from temporal, parietal, and frontal lobe sites in 12 pediatric patients undergoing evaluation for epilepsy surgery. The stimuli were presented using an oddball paradigm and consisted of short vibratory bursts applied to hand digits 2 and 3. Early sMMRs, consisting of a negative and a positive component, were recorded over the postcentral gyrus and a later one, consisting of only a negative component, was recorded over the left middle frontal gyrus. The presence of an anterior sMMR suggests similar cortical processing to the auditory mismatch negativity (aMMN), with the posterior sMMR reflecting the neuronal processes involved in discriminating between stimuli and this is then followed by the anterior sMMR that may reflect processes involved in switching attention to these changes. The presence of both a prefrontal aMMN and sMMR may reflect activity with a multimodal network. (C) 2009 Elsevier B.V. All rights reserved.