A network of occipito-temporal face-sensitive areas besides the right middle fusiform gyrus is necessary for normal face processing

Abstract

Neuroimaging studies have identified at least two bilateral areas of the visual extrastriate cortex that respond more to pictures of faces than objects in normal human subjects in the middle fusiform gyrus [the 'fusiform face area' (FFA)] and, more posteriorly, in the inferior occipital cortex ['occipital face area' (OFA)], with a right hemisphere dominance. However, it is not yet clear how these regions interact which each other and whether they are all necessary for normal face perception. It has been proposed that the right hemisphere FFA acts as an isolated ('modular') processing system for faces or that this region receives its face-sensitive inputs from the OFA in a feedforward hierarchical model of face processing. To test these proposals, we report a detailed neuropsychological investigation combined with a neuroimaging study of a patient presenting a deficit restricted to face perception, consecutive to bilateral occipito-temporal lesions. Due to the asymmetry of the lesions, the left middle fusiform gyrus and the right inferior occipital cortex were damaged but the right middle fusiform gyrus was structurally intact. Using functional MRI, we disclosed a normal activation of the right FFA in response to faces in the patient despite the absence of any feedforward inputs from the right OFA, located in a damaged area of cortex. Together, these findings show that the integrity of the right OFA is necessary for normal face perception and suggest that the face-sensitive responses observed at this level in normal subjects may arise from feedback connections from the right FFA. In agreement with the current literature on the anatomical basis of prosopagnosia, it is suggested that the FFA and OFA in the right hemisphere and their re-entrant integration are necessary for normal face processing.

Mental Imagery for Full and Upper Human Bodies: Common Right Hemisphere Activations and Distinct Extrastriate Activations

“…The predominance of right hemispheric FFA activation has been reported in previous neuroimaging studies (Kanwisher et al 1997;McCarthy et al 1997) and is consistent with the clinical finding that prosopagnosia may follow bilateral or right hemispheric damage to fusiform and lingual gyrus including the FFA (Landis et al 1998;Rossion et al 2003).…”

The fusiform face area is not sufficient for face recognition: Evidence from a patient with dense prosopagnosia and no occipital face area

“…On one hand, with respect to fusiform activation, this finding is relatively compatible with two recent studies, which have also shown FFA activation in patients with prosopagnosia. Rossion et al (2003) show faceselective activation in the right fusiform gyrus in a patient with acquired prosopagnosia. Hasson et al (2003) report that the activation for faces in their congenital prosopagnosia patient is normal with respect to the anatomical location, activation profiles and hemispheric laterality of the FFA in controls.…”

Interpreting fMRI data: maps, modules and dimensions

“…For example, in essentially all humans cortical regions can be found that respond selectively to faces (the fusiform face area (FFA) 5,6 and, in many individuals, the occipital face area (OFA)) 7,8 , to places and -to a lesser extent -to buildings (the parahippocampal place area (PPA)) 9,10 , to body parts (the extrastriate body area (EBA) [11][12][13] and, in most people, the fusiform body area 14,15 ) and to visually presented words or letter strings [16][17][18][19] (FIG. 1).…”