Ennio De Renzi

Verbal and Non-Verbal Short-Term Memory Impairment Following Hemispheric Damage

Short-term memory was investigated in 30 control and 125 unilaterally brain-damaged patients with a series of tests requiring the immediate reproduction of strings of items of increasing length. In three tests the items were auditorially presented digits or words: one test asked for oral repetition of digits, while the other two required the patient to point to written digits or to pictures. The fourth test aimed at measuring spatial span. On both the Digits Forward test and the two other verbal tests not requiring the use of speech, left brain-damaged patients were impaired in comparison to normals, while the right brain-damaged patients were not. Aphasics had a significantly shorter verbal span than non-aphasic patients with left hemisphere damage. Spatial span, on the other hand, was significantly affected by a lesion posteriorly located in either hemisphere, but not by aphasia. Two patients with an exceedingly poor verbal memory span were observed, one suffering from anomic aphasia and the other from conduction aphasia. There were also two right hemisphere damaged patients who showed an extreme reduction of spatial span, which could not be accounted for by space perceptual disorders and contrasted with a normal performance on a spatial long-term memory test.

Constructional apraxia and hemispheric locus of lesion

Summary Three groups of left brain-damaged patients (N: 70) of right braindamaged patients (N: 55) and of control patients (N: 50) were given a battery of constructive tasks: a test of copying designs, a test of copying scattered tokens and a test of copying three-dimensional block constructions. The dyspraxic subjects were identified, taking as a cut-off point the score obtained by the normal subject with the worst performance. All three tests indicated that constructive apraxia is significantly more frequent among right brain-damaged patients. The severity of the disturbance was not significantly different between the two hemispheric groups, but certain qualitative differences were noted: patients with right hemisphere damage made more errors of spatial displacement and errors of omission, especially of models or lines lying in the left half of the visual field; patients with left hemisphere lesions oversimplified the copying of the cube. When examined with a battery of intelligence tests, dyspraxics proved to be more impaired than non-dyspraxics, both in performance and verbal tasks; left brain-damaged patients did worse than right brain-damaged patients on the W. B. Verbal Scale and on Ravens P. M.; no difference between the two hemispheric groups was found on the W. B. Performance Scale. All patients were given a visual reaction time (R. T.) test, in order to obtain a measure of the severity of their brain lesions which was not biassed by hemispheric dominance for certain mental abilities. Dyspraxics showed significantly lengthened R. T. in comparison to non-dyspraxics, and this, in connection with the findings of the intellectual tests, suggested that constructional dyspraxia is a specific symptom which occurs within the setting of severe cerebral disorganization and of general mental impairment. Reaction times of right brain-damaged patients were significantly slower than those of the left; it seemed therefore appropriate to determine whether the prevalence of right dyspraxics was still present when the two hemispheric groups were equated for their R. T.: the difference obtained in this comparison failed to reach the confidence level. Therefore, it seems reasonable to ascribe the difference in frequency of constructive dyspraxia between patients with right and left cerebral lesions to the more severe brain damage of right patients rather than to dominance of the right hemisphere for constructive abilities. This hypothesis does not exclude the possibility that different mechanisms are at work in the two halves of the brain in producing constructive dyspraxia, as is suggested by the qualitative differences of the performances of the two hemispheric groups.

The Comparative Efficiency of Intelligence and Vigilance Tests in Detecting Hemispheric Cerebral Damage

Summary The application of vigilance tests to cases of focal lesions has been investigated in brain-damaged (N: 166) and control patients (N: 139). The performances of the subjects on an intelligence test (Ravens Matrices, 1938) and in two vigilance tests (Visual Reaction Time and Continuous Choice Reaction) were compared. The two vigilance test showed greater efficiency in discriminating between normal and pathological subjects than the intelligence test, if the education level was not taken into account; this difference disappeared when specific criteria of discrimination, based on the years of schooling, were applied. The discrepancy between number of subjects classified correctly and incorrectly with the single and the specific threshold methods was greater with the Matrices than with the vigilance tests. The latter two tests do no differ from each other. In the comparison of aphasic versus left non-aphasic and left-sided versus right-sided patients there were no differences in the performances on Ravens Matrices. In the Continuous Choice Reaction the aphasics showed a poorer performance than the left non-aphasic, presumably because of the importance of internal verbalization for performance on this test; no difference was found between the two hemispheric groups. In Reaction Time aphasic and left non-aphasic subjects showed similar perfomances, but the right-sided patients were markedly slower than the left-sided ones. This result was interpreted tentatively as reflecting the presence of a more severe degree of cerebral damage in the right-sided group. The hypothesis is advanced that R.T. may be regarded as a measure of the severity of a lesion, unbiassed by its localization. This hypothesis raises the problem “why is the performance on Ravens Matrices of right-sided patients, who have the more severe lesions, not worse than that of left brain-damaged patients?” It is suggested as a further hypothesis that this may be due to the fact that the left hemisphere is crucial for all intellectual tasks, verbal as well as non-verbal.

Perceptual and associative disorders of visual recognition Relationship to the side of the cerebral lesion

IN 1890, Lissauerl described the first welldocumented case of visual agnosia and proposed a subdivision of this disorder into an apperceptive and an associative form, according to which stage of the process of visual recognition was primarily af€ected. By apperception he meavt the higher level of processing of sense data (the lower level being designated as perception) which enables the subject to identify and discriminate complex patterns. In Lissauers opinion, this impairment can be evaluated by requiring the patient to [I] describe the formal features of the pattern, [2] reproduce it by drawing, and [3] recognize it among similar alternatives. The associative stage, on the other hand, consists of the linkage of the processed visual data with memory images laid down in the brain through other sensory modalities and with names, which Lissauer considered as the most simple and basic representation ( Vorstellung ) aroused by objects. Only through these linkages does apperception acquire a meaning. Lissauer assumed that his patient was affected by associative agnosia since he did not recognize objects, although he performed fairly well on purely apperceptive tasks such as discriminating arabesques. In the subsequent history of visual agnosia, the dichotomy between associative and apperceptive disorders has been somewhat neglected and attention has been concentrated on the content of the patterns the patient fails to recognize, distinguishing object agnosia, color agnosia, face agnosia, and others. This classifi-

Semantic amnesia with preservation of autobiographic memory. A case report.

A 44-year-old woman showed, following an episode of encephalitis, an impoverished knowledge of the meaning and attributes of words and their referents, in spite of intact command of grammatical-syntactic rules and preserved perceptual abilities. There was also a complete loss of the stock of notions she had acquired over her life and constituting the cultural background of a person, in contrast with normal memory for autobiographic events. The case is interpreted as an instance of semantic amnesia. MRI showed damage confined to the antero-medial part of the left temporal lobe.

Prosopagnosia in two patients with CT scan evidence of damage confined to the right hemisphere

Abstract Two patients developed a severe and long-lasting inability to recognize familiar faces (prosopagnosia) after a stroke, which was shown by CT scan to be confined to the right hemisphere. The area of softening involved the entire cortico-subcortical territory of distribution of the right posterior cerebral artery. These data suggest that in a few cases right occipito-temporal damage may be sufficient to produce prosopagnosia.

Proper name anomia.

Following a left thalamic infarct, a patient showed a marked impairment in retrieving person proper names in response to faces and to verbal description, despite being able to provide precise information about the persons he could not name and to point to their photograph when the name was provided by the examiner. The patient was also impaired in generating proper names, but could easily retrieve common names as well as geographical names and names of monuments. It is hypothesized that the arbitrary nature of the link between proper names and their referents makes access of phonological forms from the semantic store particularly labile. In agreement with this interpretation is the patients inability to recall telephone numbers and to learn semantically arbitrary paired associates.

Slowly Progressive Visual Agnosia or Apraxia Without Dementia

Abstract Two patients manifested a progressive impairment of visuoperceptive abilities and one patient a progressive generalized apraxia, in the absence of dementia and oral language disorders. The disease started in the presenium and the follow-up was of five, two and half and two years, respectively. The relation of these clinical pictures to cases of generalized dementia and to cases with isolated, progressive aphasia is discussed.

Auditory extinction following hemisphere damage

Extinction to the simultaneous presentation of sounds to both ears was investigated in patients with acute cerebrovascular disease and found to be present in nearly half of the patients in the early stage of stroke. The occurrence of the symptom was not significantly different following damage to either hemisphere, but a higher percentage of right brain-damaged patients tended to show extinction for a longer time. However, this finding must be evaluated with caution since a greater number of left- than right-hemisphere patients had to be excluded from the investigation because aphasia precluded their understanding test instructions. The presence of auditory extinction was not related to that of visual extinction and there were patients with severe visual neglect who did not extinguish in the auditory modality. These findings and CT scan evidence, indicating that patients with long-lasting extinction had lesions encroaching upon the auditory pathways, suggest that in number of cases the phenomenon may have a sensory and not an attentional basis.

The Occurrence of Visual Neglect in Patients With Unilateral Cerebral Disease

Visual neglect for the contralateral space has been reported to occur more frequently and more severely following right than left brain damage. The present study sought to determine whether this hemispheric difference is task dependent, i.e. is maximal for tests demanding a thorough exploration and minimal for tests leaving space scanning to the patients initiative. The findings supported this hypothesis. When the occurrence of neglect was assessed by means of a copying drawings test omissions of details contralateral to the involved hemisphere were found only in the right brain-damaged patient. When the patient was required to bisect a line or to choose the correct response among the alternatives of the Raven test, a tendency for preferring the homolateral hemi-space was also shown by left brain-damaged patients, although it was much more marked in the right-sided group. When patients were asked to insert balls in the holes of a board, both hemispheric groups showed a preference for the homolateral space. The incidence of constructional apraxia was evaluation in the same hemispheric groups and found not to be significantly different.