Anna Basso

Progressive language impairment without dementia: a case with isolated category specific semantic defect.

A patient is described with a 5 year progressive defect of naming and auditory verbal comprehension, the pathological nature of which was presumably degenerative. The auditory comprehension defect unevenly affected different semantic categories, and was particularly severe for the names of animals, fruits and vegetables. The patients showed loss of the verbal knowledge of the physical attributes of the concepts corresponding to the words he was unable to understand, and sparing of the verbal knowledge of the functional attributes. His performance was defective also on the colour-figure and sound-picture matching test.

Left hemisphere damage and selective impairment of auditory verbal short-term memory. A case study

The case of a left-hemisphere damaged patient with an impairment of auditory verbal memory span is described. The neuropsychological study showed a dissociation between short-term and long-term auditory verbal memory, which may be attributed to a selective defect of auditory verbal short-term memory. Since a tachistoscopic study displayed a short-term memory superiority of the left hemisphere, it can be argued that the performance for visual verbal stimuli may still be held by the left hemisphere, albeit computerized tomography showed a left-hemisphere lesion involving the whole language area.

A fMRI study of word retrieval in aphasia.

The neural mechanisms underlying recovery of cognitive functions are incompletely understood. Aim of this study was to assess, using functional magnetic resonance (fMRI), the pattern of brain activity during covert word retrieval to letter and semantic cues in five aphasic patients after stroke, in order to assess the modifications of brain function which may be related to recovery. Four out of five patients had undergone language recovery, according to standard testing, after at least 6 months of rehabilitation. The cerebral activation of each patient was evaluated and compared with the activation pattern of normal controls studied with the same fMRI paradigm. In the patients, the pattern of brain activation was influenced by the site and extent of the lesion, by the degree of recovery of language, as reflected by task performance outside the scanner, and by task requirements. In the case of word retrieval to letter cues, a good performance was directly related to the activation in Brocas area, or in the right-sided homologue. On the other hand, in the case of semantic fluency, the relationship between performance level and activation was less clear-cut, because of extensive recruitment of frontal areas in patients with defective performance. These findings suggest that the performance in letter fluency is dependent on the integrity of the left inferior frontal cortex, with the participation of the homologous right hemispheric region when the left inferior frontal cortex is entirely of partially damaged. Semantic fluency, which engages the distributed network of semantic memory, is also associated with more extensive patterns of cerebral activation, which however appear to reflect retrieval effort rather than retrieval success.

Phonemic Identification Defect in Aphasia

Eight-four right-handed patients with unilateral hemispheric damage (50 aphasics, 12 non-aphasic left brain-damaged and 22 right brain-damaged patients) and 53 control patients without cerebral lesions were given a test of phoneme identification which examined the Ss ability to identify the acoustic boundary between the two phonemes, /d/ and /t/, expressed in terms of voice-onset time (VOT). Phonemic identification defect (PID), defined with reference to the performance of the control group, was found to be virtually limited aphasics; in over 70 per cent of them, the identification of the boundary zone between voiced and voiceless consonants along the VOT continuum was either impossible or abnormal, While neither the fluency - nonfluency dimension of speech nor the level of comprehension seemed to be crucially associated with PID, some evidence pointed to disordered phonemic output as to one dimension of aphasia that is specifically related to it.

Prognostic factors in aphasia

Abstract This paper reviews the literature on prognostic factors related to recovery from aphasia. These can be regrouped under two headings: anagraphical and neurological factors. Age, sex and handedness are the anagraphical factors considered. Aetiology, site and extent of lesion, and severity and type of aphasia are the neurological ones. The effects of aphasia therapy are considered separately in more detail. Finally, the literature on patterns of recovery in groups of patients and in individual patients is reviewed. It is concluded that personal factors (age, sex, handedness) play a minor role in recovery from aphasia. Initial severity of aphasia and rehabilitation are the most important factors.

Ideomotor apraxia without aphasia and aphasia without apraxia: the anatomical support for a double dissociation.

This study aimed to verify the existence of a double aphasia/apraxia dissociation. Apraxic patients without aphasia and aphasic patients without apraxia were included in a consecutive series of patients with cortical or subcortical CT documented vascular lesions in the left hemisphere. Of 699 patients, 10 were found to be apraxic but not aphasic and 149 aphasic but not apraxic. These findings indicate an aphasia/apraxia double dissociation. This suggests that praxis and language make use of two different, partly overlapping networks.

LOSS OF MENTAL IMAGERY: A CASE STUDY

Abstract A case of loss of mental imagery following a vascular lesion of the left occipital lobe is described and discussed. The findings support a twofold (analogue and propositional) theory of neural representations of the external world. It is argued that sense-specific representations may be preserved in spite of the reported loss of imagery in the corresponding modality. the possibility that this disorder may reflect a functional disconnection between brain centres is discussed.

Crossed aphasia: one or more syndromes?

Seven strongly right-handed patients developed aphasia following a right hemisphere vascular lesion documented by computerized tomography. One patient had a severe unilateral neglect, indication of its presence were evident in three and absent in three patients. The Token Test scores were significantly higher than in matched controls. Two patients had Broca aphasia, four had Wernicke aphasia and one had agraphia. The correlation between type of aphasia and locus of lesion was not much different from that normally found in standard left hemisphere brain damaged aphasics.

Neuropsychological Follow-Up Of Patients Operated For Aneurysms Of Anterior Communicating Artery

The neuropsychological outcome of 43 patients operated for ACoA aneurysms was assessed with a battery of 15 tests, tapping a wide spectrum of cognitive abilities. As a group ACoA aneurysms patients were impaired on 8 tests, including the three assessing memory. When however, patients falling below the cut-off point determined in normal controls were considered, 42% of the sample was unimpaired and only 35% fell on two or more tests. The analysis of single cases showed that memory was often affected, but short-term memory even more than long-term memory. In addition to the well known memory disorder, the patients showed a wide range of neuropsychological defects, including language and space functions. The hypotheses that could account for this broad-based neuropsychological impairment are discussed.

Aphasia arising from purely deep lesions

In this study we investigated the relationship between deep-seated lesions of the left hemisphere and the aphasic disturbances. Thirty-seven vascular patients with CT-scan, language and neuropsychological examination carried out between 15 and 60 days post-onset were studied. Presence and frequency of apraxic disorders and acalculia are also reported. A consistent relationship between the site of the lesion and the pattern of aphasic disturbances could not be established. The most striking finding was a dissociation between oral and written expression, the latter being disproportionately impaired in a number of subjects.