Human face preference in gamma-frequency EEG activity

Abstract

Previous studies demonstrated that induced EEG activity in the gamma band (iGBA) plays an important role in object recognition and is modulated by stimulus familiarity and its compatibility with pre-existent representations. In the present study we investigated the modulation of iGBA by the degree of familiarity and perceptual expertise that observers have with stimuli from different categories. Specifically, we compared iGBA in response to human faces versus stimuli which subjects are not expert with (ape faces, human hands, buildings and watches). iGBA elicited by human faces was higher and peaked earlier than that elicited by all other categories, which did not differ significantly from each other. These findings can be accounted for by two characteristics of perceptual expertise. One is the activation of a richer, stronger and, therefore, more easily accessible mental representation of human faces. The second is the more detailed perceptual processing necessary for within-category distinctions, which is the hallmark of perceptual expertise. In addition, the sensitivity of iGBA to human but not ape faces was contrasted with the face-sensitive N170-effect, which was similar for human and ape faces. In concert with previous studies, this dissociation suggests a multi-level neuronal model of face recognition, manifested by these two electrophysiological measures, discussed in this paper.Cognitive neuroscience research has been enriched during the last decade by studies associating high-frequency EEG activity with the generation of unified perceptual representations in both vision and audition, and the activation of pre-stored memory representations (Busch, et al., 2006;Kaiser and Lutzenberger, 2003). Changing the conception that physiologically pertinent EEG frequencies are lower than 20 Hz, studies in animals (Singer and Gray, 1995) and in humans (e.g. Tallon-Baudry et al., 1996, 2003Gruber et al. 2004Gruber et al. , 2005Rodriguez et al. 1999) explored activity in a range of frequencies higher than 20 Hz, which were addressed as "gamma-band". Specifically, many studies have associated between high-level perceptual mechanisms and the so-called "induced" gamma-band activity (iGBA; for review see Bertrand and Tallon-Baudry, 2000).iGBA is a measure for local neural synchronization appearing as bursts of high-frequency EEG activity which is event-related but is not necessarily phase locked to the stimulus onset (and thus may be cancelled out in traditional ERP analysis). The amplitude of these bursts is modulated by physical stimulus attributes such as size, contrast and spatial-frequency spectrum

The Role of Gamma-Band Activity in the Representation of Faces: Reduced Activity in the Fusiform Face Area in Congenital Prosopagnosia

“…for the evoked activity of the current data [21], [11], [38], [7]). Thus, this result supports the crucial role of induced Gamma-Band activity which indexes the “activation of richer, stronger and, therefore, more easily accessible mental representations of human faces” [5, p. 1980]. The data and this interpretation is in line with the ‘representational hypothesis’ formulated by Tallon-Baudry and Bertrand, [2].…”

Uncovering Gamma in Visual Tasks

“…However their Fig. 8 (Yuval-Greenberg et al 2008) shows the peak to be slightly earlier with faces, which is consistent with the reported faster processing of faces compared with objects (for example see Itier et al 2006;Zion-Golumbic et al 2008). Therefore the decrease in 30-100 Hz gamma magnitude in the slightly earlier time window of 175-275 ms was used in the current study, as a measure of the extent to which spurious gamma is reduced.…”

Neural correlates of apparent motion perception of impoverished facial stimuli: A comparison of ERP and ERSP activity

“…Alternative possibilities for the observed data might be that gamma suppression occurs for face stimuli, or that gamma is augmented to controls and is suppressed to faces. Intracortical occipitotemporal gamma activity has been previously found to be absent for viewing impoverished faces (Engell and McCarthy, 2011), and is increased to viewing static face images (Zion-Golumbic et al, 2008; Gao et al, 2013; Engell and McCarthy, 2011; Caruana et al, 2013). In contrast, perception-related narrow-band gamma activity (Sedley and Cunningham, 2013) has been described in occipitoparietal regions at around 100 ms to visual stimulus processing (see Busch et al, 2006).…”

“…Interestingly, occipitotemporal ERP activity (N170/M170) and oscillatory EEG/MEG (gamma) activity can be dissociated by different stimulus manipulations involving static faces and face parts (Zion-Golumbic et al, 2007, 2008; Gao et al, 2013). The relationship between the N170 and gamma activity appears to be a complex one and both phenomena can exist at the same recording locations, as evidenced by direct invasive recordings from human occipitotemporal cortex (Engell and McCarthy, 2011; Caruana et al, 2013).…”