Intracranial Neurophysiological Correlates Related to the Processing of Faces

Abstract

Face perception and recognition is an intriguing ability, already present in neonates. Numerous studies in patients with brain lesions identified the temporo-occipital cortex as the crucial structure for this capacity. Analysis of electrical signals (EEG) inside the brain of patients implanted with intracranial electrodes for diagnostic purposes allows researchers to describe the temporal and spatial organization of responses to various aspects of face processing in human subjects. Several findings have emerged and appear relevant for cerebral organization in general: (1) Selective face responses were obtained from the basal temporo-occipital cortex at around 200 ms (N200); however, other structures such as the lateral temporal lobe and frontal cortex also participate in face recognition and perception tasks. (2) Each structure has a distinct "response profile"; that is, with respect to a given task certain structures respond strongly, others less or not at all. This profile might change with a different task, although the physical parameters of the stimuli remain the same. (3) The right hemispheric predominance of face processing, as suggested by patient data and studies in healthy volunteers, seemed to be restricted to its early stages (i.e., before 100 -150 ms). (4) Recognition of faces might be associated with differential intracranial responses, despite an incorrect overt response, reflecting neurophysiological correlates of implicit memory. (5) The more the stimulus resembled a complete human face, the earlier and larger the N200 response was found, in particular over the basal temporobasal cortex. Analysis of electrical signals from intracranial electrodes might help to improve our understanding of the underlying physiological and anatomical constraints of cognitive processes.

Seeing Objects through the Language Glass

“…Indeed, categorical effects have been reported in the domain of face processing in the P1 range and even earlier (Thierry et al, 2007a; Thierry, Martin, Downing, & Pegna, 2007b;Seeck et al, 1997Seeck et al, , 2001). Therefore, because it occurs beyond the P1 range, the DRN effect found here concerns relatively sophisticated levels of visual object processing-probably relating to object identity resolution.…”

Temporal precedence of emotion over attention modulations in the lateral amygdala: Intracranial ERP evidence from a patient with temporal lobe epilepsy

“…He was treated with a regular antiepileptic drug (leviracetam), which was interrupted after electrode implantation according to a standard weaning protocol. All our investigations were performed during the presurgical evaluation phase in the regular clinical setting, while the patient underwent intracranial EEG with depth electrodes in the left temporal and frontal lobes to identify the epilepsy focus (Seeck et al, 2001;Seeck et al, 1995). A written informed consent was obtained from the patient prior to his participation to this study, following the standard practice in the presurgical evaluation unit (Department of Neurology, University Hospital, Geneva).…”

Enhanced extrastriate visual response to bandpass spatial frequency filtered fearful faces: Time course and topographic evoked‐potentials mapping

“…Increased P1 amplitude during the perception of threatrelated (e.g., angry and fearful) relative to positive or neutral expressions might be consistent with behavioral [Pratto and John, 1991] and neuroimaging experiments [Armony and Dolan, 2002;Lang et al, 1998;Vuilleumier et al, 2001] showing that negative emotional events often tend to capture attention in an involuntary reflexive manner Pourtois et al, 2004]. However, such an early effect of facial expression might at first seem paradoxical, given that face detection processes are thought to involve a specialized neural system in inferotemporal cortex that is activated at a later time, around 150 -200 ms poststimulus onset, as typically indexed by the face-selective N170 component measured over occipitotemporal electrodes [Bentin et al, 1996;Schweinberger et al, 2002] or by the N200 measured intracranially [Allison et al, 1994;McCarthy et al, 1999;Seeck et al, 2001]. Thus, it remains to be determined what stimulus attribute and/or perceptual process might be responsible for this early response to fearful face expressions, and what underlying neural substrates within the distributed occipitotemporal face network might be involved [Haxby et al, 2000].…”