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LeMo, an expert system for single case assessment of word processing impairments in aphasic patients
(1997)
In his short paper of 1886, the neogrammarian linguist Delbruck sketches his views on normal language processing and their relevance for the interpretation of some of the symptoms of progressive anomic aphasia. In particular, he discusses proper name impairments, verb and abstract noun superiority and the predominance of semantically related errors. Furthermore, he suggests that part of speech, morphology and word order may be preserved in this condition. This historical document has been lost in oblivion but the original ideas and their relevance for contemporary discussions merit a revival.
Background: A prominent model of semantic processing in modern cognitive psychology proposes that semantic memory originates in everyday life experience with concrete objects such as plants, animals, and tools (Martin Chao, 2001). When the meaning of a concrete content word is being acquired, the learner is confronted with stimuli of various modalities related to the word's meaning. This comes to be stored as sensory knowledge about the object. It is further postulated that there is a conceptual domain remote from the mechanisms of perception, which is often referred to as functional knowledge or verbal semantics. There is a large body of neuropsychological literature trying to establish how much sensory and functional semantics is needed to access a name, and whether the relative contribution of these types of knowledge is the same for all categories of objects. Another controversial issue is whether naming requires access to semantic knowledge, or whether object names can be accessed directly from vision without the intervention of semantics, as is generally accepted for written word naming. Some support for this assumption seems to come from cases of so-called non-optic aphasia, a condition in which patients can name from visual presentation only but not from any other modality of presentation such as auditory, verbal, tactile, etc. In optic aphasia, a condition far better established, naming is possible from all modalities except vision. Aims: The aim of this paper is to draw attention to the first case description of non-optic or negative optic aphasia described by Wolff (1897, 1904). Methods Procedures: The case describes the results of a re-examination of Voit, who was seen by several neurologists in the course of a decade in classical aphasiology. The patient demonstrated anomia in oral but not in written naming of objects in view. Wolff's examination involves extensive testing of semantic processing in several modalities, especially with respect to the status of functional and sensory semantic features Outcomes Results: The re-examination of patient Voit by Wolff in 1897 with new procedures revealed a specific impairment in processing sensory knowledge, while functional knowledge of objects was relatively preserved. This led to a naming impairment in all modalities of presentation except the visual one. Using more refined tasks, Wolff also demonstrated receptive impairments, in contrast to previous researchers who had concluded that the impairment was restricted to oral production. Conclusions: Although Wolff's (1904) case of negative optic aphasia has been almost completely forgotten (but see Bartels Wallesch, 1996), it is astonishingly modern in its conceptual approach and in the central questions it addresses on the mechanisms involved in the process of naming and on the structure of the semantic system. As is usual in classical cases, the methodology may appear less stringent than in most contemporary work, but the approach was brilliant.
Modality-specific anomias
(1997)
Wernicke's 1903 case pure agraphia : an enigma for classical models of written language processing
(1996)
Tense and Agreement dissociations in German agrammatic speakers : Underspecification vs. hierarchy
(2005)
The aim of the present paper was to investigate whether German agrammatic production data are compatible with the Tree-Pruning-Hypothesis (TPH; Friedmann & Grodzinsky, 1997). The theory predicts unidirectional patterns of dissociation in agrammatic production data with respect to Tense and Agreement. However, there was evidence of a double dissociation between Tense and Agreement in our data. The presence of a bidirectional dissociation is incompatible with any theory which assumes a hierarchical order between these categories such as the TPH or other versions thereof (such as Lee's, 2003 top-down hypothesis). It will be argued that the data can better be accounted for by relying on newer linguistic theories such as the Minimalist Program (MP, Chomsky, 2000), which does not assume a hierarchical order between independent syntactic Tense and Agreement nodes but treats them as different features (semantically interpretable vs. uninterpretable) under a single node. (c) 2005 Elsevier Inc. All rights reserved
Recently, neurolinguistic explanations informed by linguistic theory have been proposed to account for spontaneous and elicited agrammatic speech production. These are either formulated in terms of impaired representations or they refer to impaired processing. Both have in common that they assume severe disorders of question production due to vulnerability of the left periphery of sentence structures in the representational account, of verb movement in the processing account. We report the results of question elicitation and spontaneous speech analysis in eight chronic German agrammatic speakers. The results indicate that there is not one homogeneous agrammatic pattern, but that the data reveal double dissociations which cannot be accounted for by the unitary explanations of agrammatism which are presently available. An alternative explanation will be provided which-in contrast to the representational account not only refers to global hierarchically organized nodes but relies on linguistic differences within these nodes. The assumption that they can be differentially affected in agrammatism can account for the observed patterns. (c) 2005 Elsevier Ltd. All rights reserved