ABSTRACT
Only two patients in our review showed a category-specific impairment for living or non-living things restricted to the visual modality. One of them, patient PSD, showed a selective impairment in visual recognition of living categories (Damasio, 1990). In contrast, the other patient (DRS) presented with a category-specific impairment for non-living things (Warrington & McCarthy, 1994). Anatomically, PSD showed bilateral temporo-occipital lesions, mainly involving the inferomesial parts of these lobes, whereas DRS presented with bilateral but asymmetric infarcts in the right parietal lobe and in the left inferior temporo-occipital region. The anatomical data for patient PSD are consistent with the lesion location of another patient (DRB) who had a similar visual recognition disorder selectively affecting living entities (Damasio, 1990) and with the results of a group study recently reported by Tranel, Damasio, and Damasio (1997). These authors have shown that a selective impairment for animals (observed in 19 patients) was associated with lesions involving the mesial occipital or temporo-occipital regions of both the right and the left hemisphere. In contrast, a selective impairment for tools (observed in five patients) was associated with maximal lesion overlap in the dorsolateral left temporoparieto-occipital junction areas. These data are consistent with an exclusive involvement of the ventral stream of visual processing in tasks concerning living categories and a greater involvement of the dorsal stream in those concerning man-made objects.
