Autism and the development of face processing

Abstract

Autism is a pervasive developmental condition, characterized by impairments in non-verbal communication, social relationships and stereotypical patterns of behavior. A large body of evidence suggests that several aspects of face processing are impaired in autism, including anomalies in gaze processing, memory for facial identity and recognition of facial expressions of emotion. In search of neural markers of anomalous face processing in autism, much interest has focused on a network of brain regions that are implicated in social cognition and face processing. In this review, we will focus on three such regions, namely the STS for its role in processing gaze and facial movements, the FFA in face detection and identification and the amygdala in processing facial expressions of emotion. Much evidence suggests that a better understanding of the normal development of these specialized regions is essential for discovering the neural bases of face processing anomalies in autism. Thus, we will also examine the available literature on the normal development of face processing. Key unknowns in this research area are the neuro-developmental processes, the role of experience and the interactions among components of the face processing system in shaping each of the specialized regions for processing faces during normal development and in autism.

Fig. 1

(from Kalanit Grill-Spector) Top: Posterior view of an inflated brain show regions that respond more to faces than to other visual categories (abstract object, scenes, and scrambled images). Several face selective regions shown in shades of yellow and orange are shown in the occipitalcortex, superior temporal sulcus (STS) and fusiform gyrus (i.e., “fusiform face area”, FFA). A motion senstive region (MT) and retinotopic visual areas are also shown in the occipital cortex. Bottom: Ventral view of the FFA in relation to the collateral sulcus (CoS).

Fig. 2

(from Pelphrey et al. 2002) Patterns of visual scanning of affective faces followed a stereotypical pattern in controls, outlining a triangle between the eyes and mouth. In contrast, scan paths in participants with ASD were more erratic and often excluded the internal features of the face.

Fig. 3

(from Adolphs et al. 2005) When exposed to isolated fragments of faces of fear and happiness, normal controls used information mostly from the eye region. In contrast, an amygdala damaged subject (SM) used information mostly form the mouth region.