The status of the semantic-lexical structures in anomia

This paper aims to survey recent work relevant to understanding the possible links between word-finding defects and semantic lexical disturbances in aphasic anomia. After reviewing the clinical criteria for distinguishing modality-specific anomias from the classic aphasic anomias, investigations which have given special attention to the relationships between anomia and the sensory characteristics of the stimulus are surveyed. Since results of these studies have shown that perceptual factors do not exert a significant influence upon naming in aphasia, the hypothesis that one variety of anomia may be due to a defect of the underlying semantic representation is advanced. Two varieties of aphasic anomia are described: (a) in anomics without lexical comprehension disturbances, the locus of defect seems to be outside the semantic-lexical system, namely at the level in which the lexical item corresponding to the retrieved semantic representation is specified into the appropriate phonological form; and (b) by contrast, in anomics with lexical comprehension disorders the locus of defect seems to fall inside the semanticlexical system, consisting either of a difficulty in fully accessing the semantic representation of or a loss of information at the level of the representations associated with some lexical items. Some similarities between the patterns of error presented by anomics with lexical comprehension disorders and by patients with modality-specific anomias are stressed and the possible implications of these findings for the comprehension of the underlying mechanisms are discussed.