Reduced repetition suppression to faces in the fusiform face area of adults with autism spectrum conditions.

Abstract:

In neuroimaging studies, repetitions of the same stimulus typically result in a reduction in neural activity, known as repetition suppression (RS). Repeated presentation of the same face is associated with RS in core regions of the face processing network, including the fusiform face area (FFA). At a behavioural level, repeated viewing of the same stimulus causes a change in perceptual sensitivity, known as a visual aftereffect. Evidence indicates that visual aftereffects for faces are attenuated in children and adolescents with autism spectrum conditions (ASC), leading to the proposal that atypical adaptive coding in face processing networks may underlie difficulties in face learning and memory found in ASC. However, whether individuals with ASC show reduced RS to faces remains to be addressed. Here, we used functional MRI to investigate RS to faces and non-faces (simple geometric shapes) in adults with a clinical diagnosis of ASC. We measured activity in face- and object-selective regions of occipitotemporal cortex while participants viewed blocks of images comprising repetitions of the same face/shape or images of different faces/shapes. Participants also completed standardized behavioural tests of face and car memory. Relative to age and IQ matched controls, individuals with ASC showed diminished RS to faces in right FFA. By contrast, RS to shapes in object-selective regions did not differ between groups. This finding could not be explained by differences in gaze fixations or face-selectivity in FFA. In addition, behavioural data revealed that individuals with ASC showed a significant impairment in face memory (compared to controls) but not car memory. These findings suggest reduced RS in FFA as a possible neural mechanism underlying attenuated facial aftereffects found in ASC, and suggest that differences in the adaptive properties of the face-processing network may underlie difficulties in face learning and memory associated with this condition. Meeting abstract presented at VSS 2015.