Word and face recognition deficits following posterior cerebral artery stroke:is there a common network for the recognition of faces and words?

Recent findings have challenged the existence of category specific brain areas for perceptual processing of words and faces, suggesting the existence of a common network supporting the recognition of both. We examined the performance of patients with focal lesions in posterior cortical areas to investigate whether deficits in recognition of words and faces systematically co-occur as would be expected if both functions rely on a common cerebral network. Seven right-handed patients with unilateral brain damage following stroke in areas supplied by the posterior cerebral artery were included (four with right hemisphere damage, three with left, tested at least 1 year post stroke). We examined word and face recognition using a delayed match-to-sample paradigm using four different categories of stimuli: cropped faces, full faces, words, and cars. Reading speed and word length effects were measured in a separate reading test. Patients were compared to controls using single case statistics. Combining the results from the two experiments, two patients with right hemisphere damage showed deficits in all categories. More interestingly, of the remaining patients, one with right and two with left hemisphere damage, showed deficits for both words and faces but were unimpaired when shown the control category, cars. Two other patients, one right and one left hemisphere damaged, showed a selective deficit for faces. To summarize, in all cases with word recognition deficits, impairment in face recognition was also present. However face recognition deficits did in some cases appear selectively without deficits in word or object recognition. Overall, this study supports the existence of a bilaterally distributed network for perceptual processing of faces and words, as lesions in either hemisphere may affect both functions. More interestingly, selective deficits in face recognition may be seen following lesions to either hemisphere, suggesting that parts of this bilateral network are specific for face processing. Meeting .