Biomedical subjects

G Gainotti

Publications and source records attributed to G Gainotti.

At least 19 recordsLinked to original sources

PubMed1995

Neuropsychological tests and [99mTc]-HM PAO SPECT in the diagnosis of Alzheimer's dementia.

Twenty-three patients with Alzheimer's dementia (AD) in relatively early stages and 40 patients with other cognitive disorders of vascular or degenerative aetiology underwent neuropsychological examination and [99mTc]-HM PAO single photon emission computed tomography (SPECT). In contrast to the commonly accepted notion of a posterior temporoparietal reduction of tracer uptake as the typical SPECT pattern of AD, the most consistent feature found in the SPECT images of our AD patients was a hippocampal uptake deficit, associated with a variable degree of temporal, parietal and frontal deficit (extending from the posterior to the anterior regions), according to the severity of the disease. These results support the theory of AD as a "hippocampal dementia", at least in the early stages. Neuropsychological tests were found to be somewhat more specific and more accurate than SPECT in distinguishing AD from non-AD cases.

Aged↗

PubMed1994

Evidence for a possible neuroanatomical basis for lexical processing of nouns and verbs.

Neuropsychological studies have revealed that brain-damaged patients may show impairments of specific word categories. This study reports the performance of three patients with impairments of the categories noun and verb. The first and second patients, with left frontal lobe atrophy, were impaired in naming and comprehension of verbs. The third patient, with striking atrophy of the left temporal lobe, was disproportionately impaired in naming and comprehension of nouns. These findings suggest that anatomically distinct neural systems in the temporal and frontal lobes of the dominant hemisphere might play a critical role in lexical processing of nouns and verbs, respectively.

Aged↗

PubMed1994

Disorders of verbal and pictorial memory in right and left brain-damaged patients.

It is still controversial whether verbal and pictorial stimuli are independently processed and stored in memory, as assumed by the dual code hypothesis, or a single code is used both for verbal and for pictorial stimuli, as assumed by the verbal loop hypothesis and by the propositional code hypothesis. According to the first hypothesis, verbal and pictorial memory are independently disrupted by brain damage, whereas according to the second hypothesis a co-occurrence of verbal and pictorial memory disorders are usually observed. To test these contrasting predictions, we constructed a verbal and a pictorial memory task very similar with respect to testing procedures and to material to be memorized and we administered them to 33 left and 27 right brain-damaged patients and to 21 normal controls. The following results were obtained: 1) Disorders of verbal and of pictorial memory were dissociated by brain injury in about one-third of our patients; 2) A consistent relationship was observed between laterality of lesion and type of selective memory impairment, since word recognition was selectively impaired by left and picture recognition by right brain injury; 3) However, only on the test of verbal memory was a significant difference between right and left brain-damaged patients obtained, whereas on the test of pictorial memory only a nonsignificant trend in the opposite direction was observed. These data are in favor of the dual code hypothesis and suggest that the links between left hemisphere and verbal code may be stronger than the relationship between right hemisphere and pictorial code.

Adult↗

PubMed1992

Early rightwards orienting of attention on simple reaction time performance in patients with left-sided neglect.

A specific disruption in the ability to automatically disengage attention from its previous focus has been hypothesized to account for the extinction phenomenon often observed in the unilateral spatial neglect syndrome. Recent literature, however, also brings out the role played in neglect by an imbalance in the attentional orienting systems, resulting in an early shift of attention towards the side of space ipsilateral to the brain lesion. In the present study we hypothesized that this attentional bias in orienting of attention might be demonstrated in a paradigm of simple reaction time to lateralized visual stimuli by contrasting the presence vs the absence on the computer screen of the square boxes used to facilitate position expectancy. A main prediction was made that patients with neglect would show a significant increase in reaction time to contralateral visual stimuli in the presence of bilateral reference boxes as compared to conditions in which no boxes were displayed. The right-sided box was in fact expected to exert an early attraction on the patient's attention, thus modifying the pattern of reaction times to the proper targets. This prediction was confirmed in right brain-damaged patients with moderate to severe neglect.

Adult↗

PubMed1992

Can residual lexical knowledge concern word form rather than word meaning?

We described a patient with a dramatic deficit of both word comprehension and naming but with good preservation of visual pictorial semantics. On word-picture matching, his performances were slightly better than expected based on the observed lexical semantic disorder; in addition, the patient, who maintained good preservation of his underlying phonology, showed a tendency to point to the picture phonologically related to the target. In order to interpret these data, we advanced the hypothesis that the patient, in spite of his virtually complete inability to name, would be able, in a word-picture matching task, to "covertly" (i.e., preverbally) retrieve the name from the picture and to use this name to attempt a match with the phonological form of the stimulus word. This mechanism, that we called "phonological" comprehension, would allow the identification of the correct target and would explain the choice of the phonologically related foil that was sometimes selected.

Aged↗

PubMed1992

Neuropsychological markers of dementia on visual-spatial tasks: a comparison between Alzheimer's type and vascular forms of dementia.

The incidence of the "closing-in" phenomenon and of the tendency to give "primitive answers" on the Raven's Colored Matrices was studied in 50 normal subjects and in two groups of Alzheimer's type (n = 41) and of vascular (n = 35) dementia patients, carefully matched as for the overall severity of dementia and the degree of visual-spatial impairment. The aims of this research were to determine if these patterns of behavior can be considered as neuropsychological markers of dementia and if their incidence is similar in the two dementia groups. Results show that both the closing-in phenomenon and the tendency to give globalistic and odd responses on the Raven's Colored Matrices are good markers of dementia and that, in particular, they point to a degenerative, rather than to a vascular form of dementia. From the clinical point of view, these data suggest that a qualitative analysis of the patient's behavior can increase the diagnostic efficacy of neuropsychological tests and that neuropsychological markers of dementia point more to Alzheimer's disease (considered as the most prototypic form of dementia) than to a vascular form of dementia even when the two groups of patients are well balanced in terms of visual-spatial impairment and the overall severity of dementia.

Aged↗

PubMed1991

Early orientation of attention toward the half space ipsilateral to the lesion in patients with unilateral brain damage.

Posner has suggested that unilateral spatial neglect could be due to a difficulty in disengaging attention from its current focus to orient it toward the neglected half space. Clinical and experimental data suggest, however, that this disengaging difficulty could be only one aspect of a more complex disturbance also characterized by an early automatic orienting of attention toward the half space ipsilateral to the lesion. To test this hypothesis, two different investigations in unselected groups of patients with right and left brain-damage were carried out. The first investigation, to evaluate forms of lateral orienting of attention severe enough to provoke an overt gaze deviation, consisted of the systematic assessment of the phenomenon of "magnetic gaze attraction". The second investigation, to detect milder forms of automatic orienting of attention, analysed the temporal sequence followed in identifying the pictures represented in an "Overlapping Figures task", to see if patients tended to identify first figures lying in the half space ipsilateral to the lesion. In both investigations results consistently showed: a) that patients with right brain damage tend to orient attention automatically toward the ipsilateral half space more than patients with left brain damage; b) that this tendency is tightly linked to the presence of behavioural manifestations of hemi-neglect. These results are therefore consistent with the hypothesis that hemi-neglect is a multi-component syndrome with an early orienting of attention toward the half space ipsilateral to the lesion as the first of these components.

Analysis of Variance↗

PubMed1991

Dissociation between knowledge of living and nonliving things in dementia of the Alzheimer type.

Patients who survive herpes simplex encephalitis (HSE) sometimes present a category-specific disorder for living things. Since HSE specifically involves the temporolimbic structures of both hemispheres, these structures could play a critical role in processing and storing information about living things. If this were the case, a category-specific disorder for the same items should also be observed in the early stages of dementia of the Alzheimer type (DAT) as the temporolimbic structures are often severely affected in this condition. To test this hypothesis, we administered to 15 DAT patients and to 10 normal controls a confrontation-naming task and a verbal associates recognition task, with both living and nonliving items as stimuli. The hypothesis was confirmed, since DAT patients performed worse with living than with nonliving items, and scored worse than normal controls on the living but not the nonliving items.

Alzheimer Disease↗

PubMed1990

Double dissociation between temporal and spatial pattern processing in patients with frontal and parietal damage.

One hundred and twenty nine patients affected by a cerebral lesion confined to a single lobe, underwent a battery of tests including the "Temporal Rule Induction" (TRI) and the Raven's "Coloured Progressive Matrices" (CPM). Frontal patients scored lower than any other group on TRI and parietal patients on CPM. This contrasting pattern of performance provides strong empirical support to the hypothesis that the frontal lobe is specifically involved in tasks that require a control on temporally ordered information whereas the parietal lobe is concerned with cognitive activities that imply visuo-spatial analysis.

Adult↗

PubMed1990

Contralateral and ipsilateral disorders of visual attention in patients with unilateral brain damage.

To explain the prevalence of unilateral spatial neglect in patients with right brain damage, Heilman et al have suggested that the attentional neurons of the right parietal lobe might have bilateral receptive fields, whereas the homologous cells of the left hemisphere would have strictly contralateral receptive fields. One implication of this theory is that patients with right brain damage should show a prevalence of disorders of visual attention not only in the half space contralateral to the damaged hemisphere, but also in the ipsilateral one. To check this theory, 50 control subjects, 102 right and 125 left brain-damaged patients were given a drawing completion task in which patients were requested to complete the missing parts of a star, a cube and a house. Omissions of lines lying on the sides of the models contralateral and ipsilateral to the damaged hemisphere were taken separately into account. Results did not confirm the hypothesis, since right brain-damaged patients failed to complete the contralateral sides of the models much more frequently than patients with left brain injury, but no difference was found between the two hemispheric groups when ipsilateral disorders of visual attention were taken into account. Furthermore, no correlation was found between omissions of lines lying on the sides of the models contralateral and ipsilateral to the damaged hemisphere. This finding suggests that contralateral and ipsilateral disorders of visual attention are not due to the same mechanism in right brain-damaged patients. The alternative hypothesis viewing ipsilateral disorders as resulting from a widespread lowering of general attention (and only contralateral neglect reflecting a specific disorder of visual attention) was supported by results obtained on a verbal memory test, used to evaluate the general cognitive and attention level of the patients. Patients with clear-cut ipislateral inattention obtained very low scores on this test, whereas patients with severe contralateral neglect, but not ipislateral inattention scored within the normal range on the verbal memory test.

Attention↗

PubMed1989

Can the pattern of neuropsychological improvement obtained with cholinergic drugs be used to infer a cholinergic mechanism in other nootropic drugs?

1. Enhancement of episodic memory and reduction of intrusion errors are considered as the most characteristic outcome of cholinergic drugs administration in AD patients. 2. Since the nootropic drugs Piracetam and Oxiracetam are deemed to act through a cholinergic mechanism, we checked whether AD patients treated with these drugs would show the same pattern of neuropsychological improvement. 3. Results were negative, since (a) episodic memory showed a similar degree of improvement both in patients treated with these drugs and in patients treated with placebo; (b) the number of intrusions tended to increase, rather than to decrease, after the treatment period.

Alzheimer Disease↗

PubMed1989

The influence of semantic and perceptual factors on lexical comprehension in aphasic and right brain-damaged patients.

We investigated whether the errors made by aphasic patients and right brain-damaged (RBD) patients on a word-picture matching test were differently related to the semantic and perceptual difficulties of the task. To this effect, the target picture was presented in one condition along with two semantically similar distractors, in another condition with two perceptually similar distractors, and in a third condition with two distractors that were both semantically and perceptually similar. There were also two control conditions in which part of targets that had been originally shown with semantic distractors were now presented with perceptual distractors and vice versa. The findings were consistent with the hypothesis that aphasics mainly fail when the task involves semantic discrimination and RBD patients when it involves perceptual discrimination. In aphasics the semantic perceptual condition produced the highest number of errors, but this was due, it was argued, to an increase of the semantic demands of the task.

Analysis of Variance↗

PubMed1989

Posed emotional expression in unilateral brain damaged patients.

The facial expressions of six basic emotions were posed by two groups of right (N = 23) and left (N = 34) brain damaged patients and by a control group of normal subjects (N = 28). The posed expressions were examined by means of the Facial Action Coding System (FACS) which provides analytical and objective scoring, as by a subjective scale of appropriateness of expression. Results indicated no difference between controls and patients with a lesion in the right or left hemisphere. These findings are inconsistent with the hypothesis that the right hemisphere plays a specific role in the control of posed facial expression. No relationship was observed between posed emotional expressions and facial paralysis or the presence of oral apraxia.

Affect↗

PubMed1989

Contralateral and ipsilateral tactile extinction in patients with right and left focal brain damage.

Heilman has suggested that right hemisphere lesions produce neglect both in the spaces contralateral and ipsilateral to the damaged hemisphere. To test this hypothesis, we studied the incidence of contralateral and ipsilateral tactile extinctions in 44 right and 59 left brain-damaged patients, by means of a standard test of a double tactile simultaneous stimulation of symmetrical and asymmetrical parts of the two sides of the body and of ipsilateral body parts. Results did not confirm Heilman's hypothesis; while contralateral tactile extinction was more frequent and severe in right than in left brain-damaged patients, no hemispheric difference was found when the number of ipsilateral extinctions was taken into account. Furthermore, ipsilateral tactile extinction was significantly related to aspecific factors (such as age, severity of sensorimotor impairment and widespread mental deterioration), irrespective of the hemispheric side of lesion.

Brain Diseases↗

PubMed1989

[Clinical aspects and mechanisms of visual-spatial neglect].

Several interpretations have been advanced to explain the nature of unilateral spatial neglect. According to some authors, unilateral neglect could be due to a sensory deficit or to an oculomotor disorder hampering the patient from completely exploring the half space contralateral to the damaged hemisphere. According to other authors, the unilateral neglect syndrome could result either from a mutilation of the inner representation of the outside space or from a lack of attention for stimuli falling in the half space opposite to the hemispheric locus of lesion. We have wondered whether the relationships between unilateral neglect and hemispheric lateralization could not help to understand the nature of the neglect phenomena. A retrospective analysis of data gathered in neuropsychological literature, and results of an experimental study in which we had contrasted results obtained on an "overlapping figures" task and on a visual search task and a qualitative analysis of neglect phenomena observed in right brain-damaged patients, have led to the following conclusions: a) unilateral neglect is specifically linked to right hemisphere lesions in tasks requiring extraction of information from the central part of the visual field, whereas no difference between right-sided and left-sided lesions is observed on tasks requiring a full exploration of extra-personal space; b) tasks selectively affected in right brain-damaged patients require an automatic orienting of attention toward the more peripheral parts of the stimuli, which could be partly impaired owing to an early orientation of attention toward the right side of the pattern and a subsequent difficulty to detach attention from this early focus to orient it toward parts fo the stimulus lying in the left half space.

Brain Damage, Chronic↗

PubMed1989

[Current problems in the study of aphasia].

In the introductory part of the present survey the author provides a sketchy illustration of the main anatomo-clinical aspects of aphasia, focusing attention on the main patterns of language impairment and on the corresponding cortical localizations usually observed in patients with cerebro-vascular disorders of ischemic nature. In the second part of the paper, some more recent aspects of aphasiology (namely the subcortical aphasias and the so called slowly progressive aphasia) are shortly discussed. As for the first point, it is suggested that language disorders observed in patients with purely subcortical lesions may be due to a remote effect of these lesions at the level of the cortical association areas, rather than to the subcortical injury per se. As for the second point it is still not clear if the slowly progressive aphasia is a disease or a syndrome resulting from the selective affinity for the posterior association areas of the left hemisphere of degenerative disorders, such as Pick's or Alzheimer's disease.

Aphasia↗

PubMed1988

Spontaneous facial expression of emotions in brain-damaged patients.

Spontaneous facial expression of emotion was studied in two groups of right (N = 23) and left (N = 39) brain-damaged patients and in a control group of normal subjects (N = 28). To elicit emotions four short movies, constructed to produce positive, negative or neutral emotional responses, were used. The method used to assess the facial expression of emotions was the Facial Action Coding System. Brain-damaged patients showed less facial responses to emotional stimuli than normal controls, but no difference was observed between subjects with right and left-sided lesions either with global or disaggregated data analyses, inconsistent with the hypothesis of a specialization of the right hemisphere for facial emotional expressions. An unexpected difference was observed in response to the unpleasant movie. Both normal controls and left brain-damaged patients often averted their gaze from the screen when unpleasant material was displayed, whereas right brain-damaged patients rarely showed gaze aversion. This finding suggests that the degree of emotional involvement or manner of coping with stressful input may be reduced as a result of right brain damage.

Affect↗

PubMed1986

Constructive disabilities in focal brain-damaged patients. Influence of hemispheric side, locus of lesion and coexistent mental deterioration.

The performance of 185 focal brain-damaged patients on two non-verbal constructive tasks ('Copying Drawings' and 'Copying Drawings with Landmarks') was evaluated with regard to three variables: laterality of cerebral lesion, intrahemispheric locus of lesion, and coexistence of mental deterioration. The aim of the study was to assess the relationships between each of these variables and both the incidence and severity of constructional apraxia. Different evaluations were carried out in order to partial-out the possible interference of unilateral spatial neglect. Results showed that, regardless of whether faults attributable to unilateral spatial neglect were penalized or not: right brain-damaged patients performed slightly worse and showed a higher percentage of pathologic performances than left brain-damaged patients; subjects with parietal--and particularly with right parietal--damage obtained the poorest mean scores and exhibited the highest incidence of apraxic performances; and coexistence of mental deterioration was the most relevant variable associated with global decay of constructive scores and incidence of constructional apraxia.

Adult↗