Category-specific naming deficit following cerebral infarction.

Abstract

Studies aimed at characterizing the operation of cognitive functions in normal individuals have examined data from patients with focal cerebral insult. These studies assume that brain damage impairs functions of the cognitive processes along lines that honour the 'normal' pre-morbid organization of the cognitive system. For example, detailed study of individual brain-damaged patients has revealed apparently selective disruption of cognitive functions such as auditory/verbal working memory, phonological processing ability, grapheme-to-phoneme translation procedures and semantic processing. Warrington et al. have studied patients with even more fine-grained selective disturbances of the semantic system. The most selective deficits have been reported for four patients who were significantly better at identifying inanimate objects than they were at identifying living things and foods. These patterns of selective deficit after localized brain damage provide important information about the normal organization of the lexicon, and ultimately about how components of the lexical system are related to particular neural substrates. Here, we report a case study of a patient demonstrating a very selective disturbance of the ability to name items from two related semantic categories. Despite normal performance on a large battery of lexical/semantic tasks, the patient shows a consistent and striking disability in naming members of the semantic categories of 'fruits' and 'vegetables'. The selectivity of this deficit supports a category-specific organization of the mental lexicon, and suggests independence of the processing routes involving naming and name recognition.