Electrophysiological Studies of Human Face Perception. I: Potentials Generated in Occipitotemporal Cortex by Face and Non-face Stimuli

Abstract

This and the following two papers describe event-related potentials (ERPs) evoked by visual stimuli in 98 patients in whom electrodes were placed directly upon the cortical surface to monitor medically intractable seizures. Patients viewed pictures of faces, scrambled faces, letter-strings, number-strings, and animate and inanimate objects. This paper describes ERPs generated in striate and peristriate cortex, evoked by faces, and evoked by sinusoidal gratings, objects and letter-strings. Short-latency ERPs generated in striate and peristriate cortex were sensitive to elementary stimulus features such as luminance. Three types of face-specific ERPs were found: (i) a surface-negative potential with a peak latency of approximately 200 ms (N200) recorded from ventral occipitotemporal cortex, (ii) a lateral surface N200 recorded primarily from the middle temporal gyrus, and (iii) a late positive potential (P350) recorded from posterior ventral occipitotemporal, posterior lateral temporal and anterior ventral temporal cortex. Face-specific N200s were preceded by P150 and followed by P290 and N700 ERPs. N200 reflects initial face-specific processing, while P290, N700 and P350 reflect later face processing at or near N200 sites and in anterior ventral temporal cortex. Face-specific N200 amplitude was not significantly different in males and females, in the normal and abnormal hemisphere, or in the right and left hemisphere. However, cortical patches generating ventral face-specific N200s were larger in the right hemisphere. Other cortical patches in the same region of extrastriate cortex generated grating-sensitive N180s and object-specific or letter-string-specific N200s, suggesting that the human ventral object recognition system is segregated into functionally discrete regions.

Impairments in generation of early-stage transient visual evoked potentials to magno- and parvocellular-selective stimuli in schizophrenia

“…Our findings of a large N1 component only in the high contrast (mixed M/P) and chromatic contrast (P) conditions are consistent with the N1 emerging from ventral stream based upon P system input (Allison et al, 1999;Bentin et al, 1999;Di Russo et al, 2001;Doniger et al, 2000Doniger et al, , 2001. The present findings, however, also provide a potential cautionary note regarding the study of N1 deficits in schizophrenia.…”

Autism and the development of face processing

“…The N700 is significantly larger for faces than for other stimuli [116], suggesting local generation by face-selective modules in the occipito-temporal cortex. These findings are consistent with identity-sensitive, late, unit responses from face-selective cells in the primate temporal cortex [126].…”

“…Similarly, the intracranial N200, has been recorded at discrete locations over the fusiform gyrus, the inferior temporal sulcus (ITS) and the superior temporal sulcus (STS) [116]. Possibly marking the category-recognition stage, the N170 is sensitive to features usually predictive of faces, such as isolated eyes, nose or mouth [117,118], or back views of the head, or face outlines without features.…”

Effect of configural distortion on a face-related ERP evoked by random dots blinking

“…One previous study using intracranial ERP reported that the first distinct response in visual ventral and lateral areas appears *200 ms after stimulus onset (Allison et al 1999). In contrast, N-ERP250 and P-ERP250 in this study were observed at a latency of 250 ms, about 50 ms later than in intracranial ERP.…”