Electrophysiological Studies of Face Perception in Humans

Abstract

Event-related potentials (ERPs) associated with face perception were recorded with scalp electrodes from normal volunteers. Subjects performed a visual target detection task in which they mentally counted the number of occurrences of pictorial stimuli from a designated category such us butterflies. In separate experiments, target stimuli were embedded within a series of other stimuli including unfamiliar human faces and isolated face components, inverted faces, distorted faces, animal faces, and other nonface stimuli. Unman faces evoked a negative potential at 172 msec (N170), which was absent from the ERPs elicited by other animate and inanimate nonface stimuli. N170 was largest over the posterior temporal scalp and was larger over the right than the left hemisphere. N170 was delayed when faces were presented upside-down, but its amplitude did not change. When presented in isolation, eyes elicited an N170 that was significantly larger than that elicited by whole faces, while noses and lips elicited small negative ERPs about 50 msec later than N170. Distorted human faces, in which the locations of inner face components were altered, elicited an N170 similar in amplitude to that elicited by normal faces. However, faces of animals, human hands, cars, and items of furniture did not evoke N170. N170 may reflect the operation of a neural mechanism tuned to detect (as opposed to identify) human faces, similar to the "structural encoder" suggested by Bruce and Young (1986). A similar function has been proposed for the face-selective N200 ERP recorded from the middle fusiform and posterior inferior temporal gyri using subdural electrodes in humans (Allison, McCarthy, Nobre, Puce, & Belger, 1994c). However, the differential sensitivity of N170 to eyes in isolation suggests that N170 may reflect the activation of an eye-sensitive region of cortex. The voltage distribution of N170 over the scalp is consistent with a neural generator located in the occipitotemporal sulcus lateral to the fusiform/inferior temporal region that generates N200.

Perceptual learning and inversion effects: Recognition of prototype-defined familiar checkerboards.

“…Bentin, Allison, Puce, Perez, McCarthy (1996) investigated the response characteristics of the 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 25 N170 using a target detection task in which various pictures of faces and other objects (e.g. flowers, cars) were presented and participants were monitored for the appearance of butterflies (target) in the sequence.…”

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

“…In previous studies using inverted faces (Bentin et al 1996;Honda et al 2007;Itier and Taylor 2004a;Itier et al 2006;Latinus and Taylor 2006;Sagiv and Bentin 2001;Watanabe et al 2003Watanabe et al , 2005, faces with scrambled features (George et al 1996;Latinus and Taylor 2006), and individual components such as the eyes and nose Taylor 2004a, Itier et al 2006;Shibata et al 2002;Watanabe et al 1999a), the N170 was longer in latency for inverted faces than for upright faces, regardless of the same low-level properties, such as luminance. These results indicate that N170 is related to differences in higher-level processing rather than changes in luminance and that its latency is affected by whether a subject easily and quickly detects a stimulus as a whole face or not.…”

“…For example, a schematic drawing consisting of a circle, two dots, and a straight line is recognized as a face, although no individual component of the drawing is part of a real face. Since Bruce and Young (1986) proposed the ''face recognition model'', there have been many studies of face perception using neuroimaging and electrophysiological methods (e.g., Bentin et al 1996;George et al 1996;Haxby et al 1996Haxby et al , 1999Honda et al 2007;Itier and Taylor 2004a;Itier et al 2006;Kanwisher et al 1998;Latinus and Taylor 2006;Miki et al 2007;Rossion and Jacques 2008;Sagiv and Bentin 2001;Shibata et al 2002;Watanabe et al 1999bWatanabe et al , 2002Watanabe et al , 2003Watanabe et al , 2005. In studies of event-related potential (ERP) using averaging electroencephalography (EEG) (e.g., Bentin et al 1996;George et al 1996), static human faces evoked a negative potential in the bilateral occipito-temporal areas peaking at around 170 ms, termed N170, which is considered to be sensitive to faces.…”

ERP Evidence of Atypical Face Processing in Young Children with Autism

“…Across childhood, this component was of greater amplitude to eyes and upright faces than to inverted faces (Taylor et al, 2001) similar to the adult N170. However, no direct comparison was made between upright faces and objects, such as cars (Taylor et al, 1999) in a way similar to that in adult reports (e.g., Bentin et al, 1996). The precursor N170 (prN170) is also significantly slower than the adult N170, peaking at approximately 270 ms in 4-5 year olds, and does not reach adult values (in terms of amplitude and latency) until late-adolescence.…”

“…In typical adults, the N170 component is thought to be related to early stage encoding of faces (Bentin, Allison, Puce, Perez, & McCarthy, 1996;Eimer, 1998Eimer, , 2000. The N170 is maximal over posterior temporal areas (typically measured at electrodes T5 and T6), peaks at about 170 ms after stimulus onset, is faster and larger to face stimuli compared to non-face stimuli, and does not differ based on the familiarity of the face (Bentin, Deouell, & Soroker, 1999;Eimer, 2000).…”