Early visual exposure to faces is sufficient and necessary for prepping the FFA for future specialization in tactile face processing in the blind

Abstract

The fusiform face area (FFA) is a core cortical region of face processing. Its sensitivity to faces is largely innate and tuned by visual experience. However, the nature of interaction between genetic specification and experience shaping for FFA remains unclear. In this study, we investigated the role of visual experience at different time points of an individual's early development in the cross-modal face specialization of the FFA. Subjects (n=38) consist of four groups: congenital blind, early blind, late blind and low vision. All subjects were trained for about 3 hours on tactile recognition of man-made embossed faces and other complex object categories. Functional magnetic resonance imaging (fMRI) data were acquired while subjects performed the tactile task both before and after training. While no face selective activation was detected before training in any group, results show a robust face-selective activation in the presumed FFA region in the early blind subjects after training. However, face-selective activation was not seen in FFA or other brain regions in the congenital blind or late blind subjects. Our results support a very strong genetic determination of FFA's specialization in face processing, that even after no visual experience for more than 14 years in early blind subjects, their FFA could quickly become engaged in cross-modal processing face information. Notably, the fact that no consistent face-selective activation was found in congenital blind subjects suggests that the specialization of FFA for face processing requires an initial kick-start of visual exposure to faces.

Meeting abstract presented at VSS 2018