OBJECTIVE: To 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). METHODS: IERPs 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. RESULTS: IERPs 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. CONCLUSIONS: Our 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. SIGNIFICANCE: IERP study disclosed that visual recognition occurred sequentially from posterior to anterior ITC.
OBJECTIVE: To 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). METHODS: IERPs 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. RESULTS: IERPs 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. CONCLUSIONS: Our 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. SIGNIFICANCE: IERP study disclosed that visual recognition occurred sequentially from posterior to anterior ITC.