CATEGORY SPECIFIC SEMANTIC IMPAIRMENTS

TLDR

Clinical observations suggest selective impairment of certain visual categories. The study quantitatively assessed visual identification and auditory comprehension deficits in four partially recovered herpes simplex encephalitis patients. The patients exhibited a marked dissociation between inanimate and living/food object identification, similar patterns across visual and verbal modalities, superior abstract word comprehension, and modality‑specific consistency, supporting category‑specific, modality‑dependent semantic organization.

Abstract

We report a quantitative investigation of the visual identification and auditory comprehension deficits of 4 patients who had made a partial recovery from herpes simplex encephalitis. Clinical observations had suggested the selective impairment and selective preservation of certain categories of visual stimuli. In all 4 patients a significant discrepancy between their ability to identify inanimate objects and inability to identify living things and foods was demonstrated. In 2 patients it was possible to compare visual and verbal modalities and the same pattern of dissociation was observed in both. For 1 patient, comprehension of abstract words was significantly superior to comprehension of concrete words. Consistency of responses was recorded within a modality in contrast to a much lesser degree of consistency between modalities. We interpret our findings in terms of category specificity in the organization of meaning systems that are also modality specific semantic systems.