PubMed · 1768451
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J Ferrero Arias. [Conduction aphasia].. https://pubmed.ncbi.nlm.nih.gov/1768451/
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We report two aphasic patients who could discriminate Japanese syllables but could not identify them. Case 1 was a 51-year-old right handed woman with 12-year education. Case 2 was a 50-year-old right handed man with 9-year education. They developed fluent aphasia after a cerebral infarction. Brain MRI of case 1 revealed widely distributed lesions including inferior frontal, superior temporal, angular and supramarginal gyri. Lesions revealed by Brain CT in case 2 included the left superior and middle temporal, angular and supramarginal gyri. Both showed severe impairment of repetition and confrontation naming. No difference of performance was present between repetition of single syllables and polysyllabic words. On the contrary, oral reading of Kana characters were preserved. We examined their ability to perceive syllables in detail. In the discrimination task, they judged whether a pair of heard syllables was same or different. Case 1 was correct in 85% of the tasks and case 2 in 98%. In an identification task, they heard a syllable and chose a corresponding Kana, Kanji, or picture out of 10 respective candidates. Case 1 was correct only in 30% and case 2 in 50% of these tasks. On the other hand, selection of a correct target in response to a polysyllabic word was much better, i.e. 70% in case 1 and 90% in case 2. Based on these data we concluded that (1) syllabic identification is a different process from syllabic discrimination, and (2) comprehension of a polysyllabic word can be achieved even when the precise phonological analysis of continuent syllables are impaired.
Two right-handed patients who exhibited language disability after left frontal infarction are described. The patients spoke fluently and exhibited excellent repetition ability from the onset of infarction without exhibiting any oral apraxia, but had deficits in auditory comprehension, naming, reading and writing. In both patients, brain magnetic resonance imaging (MRI) revealed infarction in the left inferior frontal gyrus, the middle frontal gyrus and the anterior part of the lower precentral gyrus. Single photon emission computed tomography (SPECT) revealed decreased blood flow in the same regions as those shown to be infarcted by MRI. The MRI and SPECT findings and the symptoms of these patients suggest that left frontal lesions that encompass Broca's area produce fluent aphasia if the posterior part of the left precentral gyrus or motor cortex remains intact and that lesions anterior to Broca's area and the middle frontal gyrus produce a deficit in auditory comprehension of single words as well as sentences.
On tests of autobiographical memory, patients with semantic dementia demonstrate significantly better retrieval of episodic events from the recent past compared with the distant past. This reversal of the Ribot effect has been attributed to the relative sparing of the hippocampal complex in the disorder. Current computational models of long-term memory predict a similar time-dependent pattern of impairment on tests of remote semantic memory. Five patients with semantic dementia were tested on recognition (familiarity) and identification (knowledge) of famous names selected from four different time-periods: 1950's, 1980's, 1990-1993 (early 1990's) and 19941996 (current). As expected, it was found that one patient DM (who had focal left temporal lobe atrophy) showed no significant impairment on recognition of famous names, but was significantly better at producing information about people who were currently famous compared to people famous in the other three time-periods. The other four patients (who had bilateral temporal lobe damage) showed better recognition of famous names from the current time-period (and to a lesser extent the 1950's), yet were profoundly impaired on the identification component, producing very little information across all four time-periods. The results are discussed with respect to current views of the neural organisation of person-specific and general semantic memory.