Visual processing in the inferior temporal cortex: An intracranial event related potential study

ObjectiveTo investigate visual processing over the inferior temporal cortex (ITC) by recording intracranial event-related potentials (IERPs), and correlating the results with those of electrocortical stimulation mapping (ESM).MethodsIERPs to word, non-word, and non-letter visual stimuli were recorded over the ITC in 6 patients with intractable epilepsy. Two patients underwent ESM of the same contacts.ResultsIERPs were observed at 18 electrodes in 4 out of 6 patients. Nine electrodes showed early IERPs (peak latency ? 200 ms) over the posterior and middle ITC and 7 of them showed a following late ERP component, “early + late IERPs”. Nine electrodes showed late IERPs (peak latency > 200 ms) over the middle and anterior ITC. Among four electrodes showing language or visual phenomena by ESM, one electrode showed a short latency IERP, another electrode showed a late IERP, and the remaining two electrodes showed no IERPs.ConclusionsOur findings further support that the visual recognition occurred sequentially from posterior to anterior ITC. Dissociation of IERPs and ESM may be explained by the methodological difference.SignificanceIERP study disclosed that visual recognition occurred sequentially from posterior to anterior ITC.