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Biomedical subjects

G Vallar

Publications and source records attributed to G Vallar.

At least 73 records · Page 4Linked to original sources
PubMed1989

Influence of response modality on perceptual awareness of contralesional visual stimuli.

Visual extinction on double simultaneous stimulation was investigated in left and right brain-damaged patients in two response conditions: verbal and motor. In right brain-damaged patients contralesional detection was significantly worse when monitored by motor rather than by verbal responses in condition of single as well as of double stimulation. Previous research in normal subjects had shown that the left hemisphere is selectively involved in choice reactions such as those occurring in the motor condition of the present experiment in brain-damaged patients. The results of the latter are interpreted using as a basis the findings of that research and Kinsbourne's hemisphere activation hypothesis concerning unilateral neglect of space.

Analysis of Variance↗
PubMed1989

Danazol and internal carotid artery thrombosis.

The case of a 47-year-old woman suffering from a CT-assessed ischemic right hemisphere stroke, which occurred after a 2-month treatment with danazol (a synthetic androgen), is reported. The patient's thrombocytosis in association with danazol treatment and its possible correlations with the thrombotic event are discussed.

Carotid Artery Thrombosis↗
PubMed1988

Patterns of lateralization and performance levels for verbal and spatial tasks in congenital androgen deficiency.

The effects of congenital deficiency of gonadal hormones on verbal and spatial performance and on the establishment of hemispheric asymmetries were investigated in a group of patients with idiopathic hypogonadotropic hypogonadism. The patients showed a left hemispheric advantage for verbal material and were mildly impaired, mainly on tasks involving a short-term memory load, in comparison with a matched control group. These results do not indicate a specific role of gonadal hormones on the establishment of hemispheric asymmetries. Lack of exposure during brain development results in a decrease in memory functions which is not specific for verbal or spatial material.

Adolescent↗
PubMed1988

Left hemisphere contribution to motor programming of aphasic speech: a reaction time experiment in aphasic patients.

Simple reaction time to lateralized visual dot stimuli was studied in 10 fluent and 10 nonfluent right-handed chronic aphasics with left hemisphere lesions. As well as the standard simple reaction time condition, the patients were given a concomitant verbal task, requiring overt articulation while reacting to the visual stimuli. Compared with the control condition, in both aphasic groups the verbal task produced an overall lengthening of latencies, with a significant slowing down of responses to the stimuli located in the right visual half-field. According to these results the verbal concurrent activity appears to involve the left hemisphere as in normal subjects, suggesting that the undamaged regions of the left hemisphere have a role to play in the motor programming of aphasic speech. As a collateral finding, the difference between latencies to stimuli ipsilateral and contralateral to the responding hand--a measure of interhemispheric transmission time--is greatly increased in patients with motor deficits. This is consistent with the view that, in simple visuo-motor reaction time, interhemispheric transfer takes place between anterior regions of the brain.

Adult↗
PubMed1988

The role of the left hemisphere in decision-making.

The role of the left hemisphere in decision-making processes in choice reactions to unstructured visual stimuli (Bisiach, Mini, Sterzi and Vallar, 1982) was further investigated in normal right-handed individuals. Subjects were required to provide a motor response to lateralized single dots, abstaining from giving a response when two dots were shown. In the first study, in which the disruptive effects of concurrent articulatory activity were assessed, the decision required integration of information provided to both hemispheres, as the no-go stimulus was constituted by two dots symmetrically positioned, one in each half-field. In the second study, all information relevant to the decision was available to each hemisphere, as the no-go stimulus was represented by two dots in either half-field. Since in both experiments the decision mechanism remained located in the left hemisphere, the following conclusions are drawn: (i) the right hemisphere is unable to fulfil the demands of the present decision-making task, even when either a secondary task interferes with left hemisphere processes or it has direct acces to all the relevant information; this suggests a pattern of absolute hemispheric specialization; (ii) the left hemisphere decision-making process does not rely upon any sort of articulatorily-based "inner speech" component.

Analysis of Variance↗
PubMed1988

Recovery from aphasia and neglect after subcortical stroke: neuropsychological and cerebral perfusion study.

Cortical regional cerebral perfusion was assessed by N, N, N1-trimethyl-N1-(2)-hydroxy-3-methyl-5-(I-123) iodobenzyl-1, 3-propanediamine 2 HCl I-123 (HIPDM) and single photon emission computerised tomography (SPECT) in six aphasic and two neglect patients with unilateral subcortical vascular lesions. Assessments were carried out both in the acute phase and after a period ranging from 1 to 6 months after stroke onset. In all patients an almost complete spontaneous recovery occurred and was associated with a significant improvement of cortical perfusion. A relationship between severity of aphasia and degree of cortical hypoperfusion was found, in both the acute and the follow up assessments, in the aphasic subgroup.

Adult↗
PubMed1988

Low doses of ketazolam in anxiety: a double-blind, placebo-controlled study.

A multicenter, double-blind, between-patient trial comparing two doses of ketazolam (15 and 30 mg) with placebo, each given once daily, in the evening, to 92 outpatients affected by generalized anxiety disorders for at least 1 month, was carried out. After 1-week washout period 47 patients were randomized to ketazolam 15 mg, and 45 to placebo for 15 days (first period). At the end of this period, if the patient experienced a decrease on the total Hamilton Anxiety Rating Scale (HAM-A) of at least 25% of basal value, the treatment was kept unchanged for a further 15 days, otherwise 15 mg of ketazolam were added to the previous treatment (second period). Anxiety was rated after 2 and 4 weeks with the Italian HAM-A scale and with a 4-point scale (patient's assessment). Seventy-eight patients completed the first period and 75 the whole study. During the first period the percentage of responders was almost identical in both treatment groups, but during the second period a further slight improvement was observed in the early placebo responders, while the HAM-A score of patients on ketazolam continued to improve significantly (p less than 0.01) throughout the study. Likewise a significant (p less than 0.001) difference between treatments was observed, on the 4-point scale, in the population as a whole (end of first period) as well as in responder patients (end second period). Tolerability was good, except in 1 patient on placebo, who was withdrawn from the study because of severe headache.

Adolescent↗
PubMed1988

Technetium-99m HM-PAO-SPECT study of regional cerebral perfusion in early Alzheimer's disease.

Regional cerebral perfusion was evaluated by single photon emission computed tomography (SPECT) using technetium-99m hexamethylpropyleneamine oxime ([99mTc]HM-PAO) in sixteen patients with Alzheimer's disease (AD) in early clinical phase and in 16 healthy elderly controls. In all patients transmission computed tomography (TCT) and/or magnetic resonance imaging (MRI) did not show focal brain abnormalities. Relative to normal subjects, AD patients showed significant reductions in cortical/cerebellar activity ratio: cortical perfusion was globally depressed with the largest reductions in frontal and posterior temporo-parietal cortices. Asymmetries of relative perfusion between cerebral hemispheres were also demonstrated when language was affected or visuospatial functions were unevenly impaired. In patients with early AD, SPECT provides functional information to be compared with clinical and psychometric data.

Aged↗
PubMed1987

Verbal and spatial immediate memory span: normative data from 1355 adults and 1112 children.

Norms are provided for verbal and visuo-spatial immediate memory span, two tasks widely used in the clinical assessment of short-term memory and its neurological disorders. Data have been collected from 1355 male and female adult subjects, with various educational backgrounds and a 20-99 years age range. Span shows a major decrement after the late sixties and is affected by educational level. Male subjects score better on the spatial task. Data collected from 1112 male and female children, 4-to-10 year-old, show that span increases with age and boys score better on the spatial test.

Adult↗
PubMed1987

Remission of hemineglect and anosognosia during vestibular stimulation.

The effects of vestibular stimulation on extrapersonal and personal neglect and on awareness of disease were investigated in four patients with severe neglect and anosognosia. Neglect phenomena improved in all patients, while an effect on anosognosia was found in two cases. These preliminary findings indicate a possible role of vestibular stimulation on hemispheric activation.

Aged↗
PubMed1987

Aphasia and neglect after subcortical stroke. A clinical/cerebral perfusion correlation study.

Sixteen patients with unilateral subcortical haemorrhagic or ischaemic stroke, confirmed by CT, were evaluated for the presence of aphasia and neglect. Compared with patients without neuropsychological deficits, left brain-damaged aphasic and right brain-damaged neglect patients showed a significantly greater reduction of cortical perfusion on N,N,N1-trimethyl-N1-(2)-hydroxy-3-methyl-5-(I-123) iodobenzyl-1,3-propanediamine 2 HCl I-123 (HIPDM) and single photon emission computerized tomography (SPECT). These results suggest that major cortical derangement is the crucial factor for the appearance of aphasia or neglect after a subcortical stroke. These remote effects, which are related to the size of the subcortical lesion, are interpreted in terms of interruption of neural connections (diaschisis).

Adult↗
PubMed1986

Balint syndrome: a case of simultanagnosia.

We describe a patient with a bilateral posterior lesion, who showed optic ataxia, gaze apraxia and the symptom which most authors call the inability to see more than one thing at a time. We discuss the last feature and the term simultanagnosia sometimes used to indicate it. Furthermore we stress the unusual localization of the lesion in this patient.

Aged↗
PubMed1986

The anatomy of unilateral neglect after right-hemisphere stroke lesions. A clinical/CT-scan correlation study in man.

The anatomical correlates of extrapersonal visual neglect were investigated in 110 right-handed stroke patients with lesions confined to the right hemisphere. Neglect is much more frequently associated with retrorolandic damage, as compared with frontal lesions. The inferior parietal lobule appears to be the area most frequently involved in patients with cortical lesions showing signs of neglect. When the cerebral lesion is confined to deep structures, neglect occurs much more frequently when grey nuclei such as the thalamus and the basal ganglia are damaged; a remarkable number of negative cases were, however, found. Conversely, lesions limited to the subcortical white matter are rarely associated with neglect. The relevance of these results to anatomophysiological models of directed attention and neglect is discussed.

Adult↗
PubMed1986

Unilateral neglect: personal and extra-personal.

Ninety-seven right brain-damaged patients were given two tasks aimed at assessing unilateral neglect in personal and in extra-personal space. The frequency of the two aspects of neglect, as well as their patterns of association with each other and with more elementary neurological disorders are reported and discussed. The results suggest a non-unitary frame of spatial reference for unilateral neglect, which may tentatively be interpreted in terms of a personal vs extra-personal dichotomy.

Animals↗
PubMed1986

Unawareness of disease following lesions of the right hemisphere: anosognosia for hemiplegia and anosognosia for hemianopia.

Unawareness of motor and visual-field defects was investigated in 97 right brain-damaged subjects. Both kinds of anosognosia were found to be double-dissociated from more elementary neurological disorders and from personal and extra-personal neglect. The relationships between anosognosia and unilateral neglect are discussed and allusion is made to the implications concerning the neurological organization of higher control functions.

Adult↗
PubMed1986

Phonological short-term store and the nature of the recency effect: evidence from neuropsychology.

The recency effect in immediate recall of lists of unrelated words was investigated in P.V., a left hemisphere-damaged patient, who had a grossly reduced auditory verbal span, attributed to a selective impairment of a phonological short-term store. No recency effect was evident in free recall of auditorily presented material. When the patient was instructed to recall the final items of the list first, the recency performance remained defective, even though P.V. was able to adopt a recall from end order. In the case of visual presentation, P.V.'s free recall performance was within the normal range and a clear recency occurred in the recall from end condition. These results are consistent with the view that the standard recency effect in immediate free recall of auditorily presented material represents the output of a phonological short-term store to which ordinal retrieval strategies, in P.V.'s case unimpaired, are applied. Finally, the contributions of the phonological short-term store and the process of rehearsal to the recency effect and to immediate memory span performance are discussed.

Adult↗
PubMed1986

Aphasia does not always follow left thalamic hemorrhage: a study of five negative cases.

Five right-handed patients suffering from a recent CT-assessed left posterior thalamic hemorrhage are reported. In all patients a standard language examination performed within one month after stroke onset did not reveal aphasic disturbances. While the present series argues for the role of intrathalamic lesion localization, a review of the literature suggests that lesion site per se does not always account for the presence or absence of aphasia in the individual case. The importance of reduced blood flow and metabolism in cortical areas which appear undamaged on CT scan is briefly discussed.

Aged↗