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Biomedical subjects

G Vallar

Publications and source records attributed to G Vallar.

90 records · Page 5Linked to original sources
PubMed1984

Selective visual interference with right hemisphere performance in verbal recall. A divided field study.

Three experiments were performed in normal subjects to find out whether interhemispheric functional asymmetries in oral recall of meaningless trigrams of consonants, laterally presented through a tachistoscope, were affected by the subsequent presentation and the immediate recall of visual (verbal and geometrical) vs auditory information. It was shown that the visual presentation of after-target information brought about a right hemisphere disadvantage, which did not occur when the additional information was presented auditorily. The results are consistent with the view that, as to visually presented letters, the right hemisphere processing systems run along a physical code.

Adult↗
PubMed1984

Disorders of perceived auditory lateralization after lesions of the right hemisphere.

The disorders of perceived auditory lateralization after unilateral damage of the cerebral hemispheres were investigated by dichotic presentation of pure tones, lateralization being obtained by interaural intensity differences. Observations were made on 107 unilateral brain-damaged patients and 30 normal subjects who were required to localize the perceived position of fused sound images. The images were generated by dichotic stimuli delivered through headphones and the patients were asked to point the perceived position. A clear-cut hemispheric asymmetry was found. Whereas left brain-damaged patients and right brain-damaged patients without visual field defects were not impaired in this task in comparison with controls, the performance of right brain-damaged patients with visual field defects was defective, with a systematic directional error towards the right side, that is, the side ipsilateral to the damaged hemisphere. The defect of auditory lateralization involved both the half-space contralateral to the lesion and the ipsilateral one. Different hypotheses are discussed in order to explain the present results. It is argued that they cannot easily be interpreted in terms of defective processing of sensory information and the proposal is made that lesions of the right hemisphere may produce a distortion of the internal representation of egocentric space to the right, yielding a systematic error of auditory lateralization are discussed.

Attention↗
PubMed1983

Line bisection and cognitive plasticity of unilateral neglect of space.

Patients with neglect of the left half of space were asked to bisect lines of different lengths. The leftmost points of the represented lines, determined on the basis of the midpoints set by the patients on the objective lines, were the dependent variable. It was thus possible to recognize diverse patterns of behavior which were conceivably averaged away in earlier investigations. In discussing the results, the question is raised of whether unilateral neglect of space may be altered by cognitive processes.

Attention↗
PubMed1982

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.

Adult↗
PubMed1982

Dissociation between normal hemispheres in delayed recognition of verbal and spatial cues of the same visual pattern.

Is each hemisphere capable of disentangling a specific kind of information from a complex 3-target set of stimuli in an expectancy-free delayed recognition experiment on normals? A tachistoscopical study set out to answer this question. It provided evidence for a double dissociation between the hemisphere of input of complex stimuli (comprising both spatial and verbal information) and the kind of information to be retrieved.

Adult↗
PubMed1982

Hemispheric lateralization of the decisional stage in choice reaction times to visual unstructured stimuli.

Simple manual RTs to lateral visual stimuli were found to be faster in uncrossed than in crossed anatomical conditions. Neither hand nor hemifield effects were found. By contrast significant asymmetries were found in Choice RTs involving both hemispheres, even in uncrossed condition. The field effect was marked when the responding hand was the right but insignificant when the responding hand was the left. The data seem consistent with a model which assumes the location of the decisional structures in the left hemisphere.

Choice Behavior↗
PubMed1980

Cerebellar softening.

Twenty-one adults with acute cerebellar softening confirmed by computerized tomography (CT) were divided into two groups according to clinical course. CT findings, and outcome. In the first group, consisting of 6 patients, the condition ran a progressive course, with deterioration of consciousness, signs of brainstem compression, and the appearance of hydrocephalus on CT scan. Three patients underwent surgery successfully, 2 died postoperatively, and 1 recovered spontaneously. In the second group, comprising 15 patients, the course was benign: cerebellar symptoms and signs improved without surgery, and only discrete cerebellar signs remained a month after onset.

Acute Disease↗
PubMed1980

The hemispheric side of neocortical damage does not affect memory for unidimensional position. An experiment wih Posner and Konick's test.

The role of neocortical areas in visuo-spatial memory was investigated by testing unilateral hemisphere-damaged patients for their ability to reproduce the position of a dot on a horizontal line after a delay. One hundred and eleven patients, divided into 4 groups on the basis of the side of damage and of the presence or absence of visual field defects, and 56 controls were tested. There were 2 sets of experimental conditions: (i) a free delay condition of 0, 20 or 180 sec., and (ii) a 20 sec. delay condition filled with 2 kinds of interpolated perceptual activity. Forgetting was significantly affected by presence of hemisphere damage, but not by the side and the intrahemispheric locus of lesion. It was concluded that the memory ability involved by this task is not related to the functioning of a specific cortical area.

Adolescent↗
PubMed1980

Amnesic syndrome after carbon monoxide poisoning. A case report.

A patient is described who after a carbon monoxide poisoning presented an amnesic syndrome. The neuropsychological investigation suggests that carbon monoxide amnesia shares common features with hippocampal amnesia, namely a discrepancy between a normal Short-Term Memory (STM) and a hampered Long-Term Memory (LTM). CT findings in our patient showed both widespread and focal areas of demyelination. The correlation between neuropsychological data and CT findings are discussed.

Adult↗
PubMed1978

A preliminary experiment on long-term memory with realistic and abstract visual patterns in uniltateral focal hemisphere-damaged patients.

Sixty-seven focal hemisphere-damaged patients (38 to the left hemisphere and 29 to the right hemisphere) were tested for forgetting of realistic and abstract visual patterns over a 40-sec to 5-min interval by means of a recognition task. No forgetting took place in any group, even if abstract patterns proved to be poorly recognized both at 40 sec and at 5 min. The authors conclude that focal neocortical unilateral lesions do not significantly hamper the semantic code processes involved in the Long-Term Memory of the patterns employed in this experiment.

Adult↗
PubMedDate not supplied

[Natural history, treatment and outcome of cerebellar softening (author's transl)].

21 adults with acute cerebellar softening were divided into two groups. In the first group (6 patients) the clinical course was progressive with deterioration of consciousness, signs of brain-stem compression and some degree of enlargement of ventricles (CT scan). Of these patients, three were treated surgically with success, one recovered spontaneously and two others died post-operatively. In the second group (15 patients) the course was much more favourable. Without surgery the cerebellar symptoms and signs improved, in spite of the persistence of discrete cerebellar signs one month after the onset of symptoms. Medical and/or surgical treatment of the disease are discussed, including the differential diagnostic aspects as well as the CT scan features.

Cerebellar Diseases↗