The correlates of subjective perception of identity and expression in the face network: An fMRI adaptation study

Abstract

The recognition of facial identity and expression are distinct tasks, with current models hypothesizing anatomic segregation of processing within a face-processing network. Using fMRI adaptation and a region-of-interest approach, we assessed how the perception of identity and expression changes in morphed stimuli affected the signal within this network, by contrasting (a) changes that crossed categorical boundaries of identity or expression with those that did not, and (b) changes that subjects perceived as causing identity or expression to change, versus changes that they perceived as not affecting the category of identity or expression. The occipital face area (OFA) was sensitive to any structural change in a face, whether it was identity or expression, but its signal did not correlate with whether subjects perceived a change or not. Both the fusiform face area (FFA) and the posterior superior temporal sulcus (pSTS) showed release from adaptation when subjects perceived a change in either identity or expression, although in the pSTS this effect only occurred when subjects were explicitly attending to expression. The middle superior temporal sulcus (mSTS) showed release from adaptation for expression only, and the precuneus for identity only. The data support models where the OFA is involved in the early perception of facial structure. However, evidence for a functional overlap in the FFA and pSTS, with both identity and expression signals in both areas, argues against a complete independence of identity and expression processing in these regions of the core face-processing network.

Predictive codes of familiarity and context during the perceptual learning of facial identities

“…Lesions to this region can cause prosopagnosia 25 , the inability to recognize the identity of familiar individuals, while leaving the ability to detect the presence of a face intact. Numerous studies that have employed fMRI adaptation paradigms have demonstrated the sensitivity of the FFA to differences in face identity 21,[26][27][28][29][30] . In such paradigms the FFA shows a decreased response when one face stimulus is presented twice in rapid succession, when compared with the response when two novel stimuli are presented in the same manner.…”

“…The STS contains patches of cells that are face-selective in monkeys 3,41 . In human neuroimaging repetition suppression studies the posterior portion of the STS is known to be sensitive to gaze direction and emotional expressions 42 , but also shows sensitivity to facial identities 21,28 . If the STS processes such a variety of different types of information about faces, what is its role is face perception?…”

“…Within this core face perception network, the fusiform gyrus (specifically the fusiform face area or FFA) and a portion of the superior temporal sulcus (STS) are purportedly important for the process of recognizing the identity of faces 18 . Neuroimaging studies have highlighted how each of these areas show differential responses for correct versus incorrect face recognition and for familiar compared with unfamiliar faces processing [19][20][21] . In addition, these areas have been shown to respond, to a certain degree, to faces regardless of the viewpoint from which they are being perceived 22,23 .…”

Deficits in face perception in the amnestic form of mild cognitive impairment

“…Functional imaging studies in healthy subjects have identified a fusiform face area (FFA) in the lateral aspect of the fusiform gyrus that is activated more by faces than other objects [24][25][26], and which may be involved in discriminating the structural aspects of faces relevant to facial identity [27]. Prosopagnosic patients with right fusiform lesions are impaired in the perception of facial structure, especially the configuration or spatial arrangement of features within a face [28].…”

The Neuropsychology of Familiar Person Recognition from Face and Voice

“…The role of these different regions is controversial. Thus, a hierarchy has been proposed between the Occipital cortices, which show sensitivity to physical properties of a face (Pitcher, Walsh & Duchaine, 2011), and the FFA that could be involved in perceiving identity (Fox, Moon, Iaria & Barton, 2009). However, Rossion, Caldara, Seghier, Schuller, Lazeyras & Mayer (2003) and Rossion (2008), have proposed a reverse hierarchical model of face perception, which assumes that re-entrant, interactions may also exist between FFA and lower order (OFA) visual areas.…”