Preference for animate domain sounds in the fusiform gyrus of blind individuals is modulated by shape-action mapping transparency

Abstract

In high-level visual shape areas in the human brain, preference for inanimate objects is observed regardless of stimulation modality (visual/auditory/tactile) and subjects visual experience (sighted/blind individuals), whereas preference for animate entities seems robust only in the visual modality. Here, we test a hypothesis explaining this effect: visual shape representations can be reliably activated through different sensory modalities when they are systematically related to action system representations. We studied fMRI activations in congenitally blind and sighted subjects listening to animal, object, and human sounds. We found that, in blind individuals, the typical anatomical location of the fusiform face area responds to human facial expression sounds, with a clear mapping between the facial motor action and the resulting face shape, but not to speech or animal sounds. Using face areas activation in the blind subjects we could distinguish between specific facial expressions used in the study, but not between specific speech sounds. We conclude that auditory stimulation can reliably activate visual representations of those stimuli - inanimate or animate - for which shape and action computations are transparently related. Our study suggests that visual experience is not necessary for the development of functional preference for face-related information in the fusiform gyrus.