Abstract
Background: The classic cases of prosopagnosia described by Meadows (1974) and Damasio et al (1982) had bilateral medial occipitotemporal lesions. While cases with right-sided lesions have been described since, the impact of such classic lesions on the face network and various aspects of face processing are unknown. Objective: We studied a patient with bilateral occipitotemporal infarcts including both middle fusiform gyri, to determine the impact of the lesions upon the face processing network on functional MRI, correlate this with results on a behavioural battery, and compare these to prior subjects with unilateral lesions affecting the right fusiform face area (FFA) and/or occipital face area (OFA). Methods: We used the dynamic face localizer in functional MRI to characterize the core face processing network. In a perceptual battery, we evaluated face recognition, face perception, face imagery, and semantic knowledge about famous people. The subject had an event-related potential study of the face-selective N170. Results: There was no activation of either right or left FFA, or left OFA, but sparing of both pSTS (posterior superior temporal sulci). He was severely impaired in discrimination of facial configuration and features, and impaired in car and handwriting recognition. He performed normally on face imagery and semantic knowledge of famous people. There was no face-selectivity in the right N170 response, and in fact showed a larger left N170 response to objects than faces. Compared to R-IOT4, who had a lesion of the right FFA, he had more difficulty with same-view matching of faces, and other within-class object recognition. Conclusions: The bilateral medial occipitotemporal variant of prosopagnosia, with loss of both FFA and the left OFA, is associated with severe deficits in processing facial structure, associated recognition impairments for other object classes, as well as loss of the N170 response in the right hemisphere.
Meeting abstract presented at VSS 2013