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Biomedical subjects

G Gainotti

Publications and source records attributed to G Gainotti.

At least 127 records · Page 7Linked to original sources
PubMedDate not supplied

Neuroanatomical correlates of category-specific semantic disorders: a critical survey.

Previous studies of category-specific semantic disturbances have focused their attention on the intrinsic cognitive structure of these disorders. The present survey aims to evaluate the relationships between disrupted semantic category and localisation of the underlying brain damage, in order to establish whether the injured brain areas house just those neurophysiological mechanisms that should have critically contributed to the acquisition of the disrupted semantic categories. We took into account in our review two double dissociations concerning respectively: (1) the impairment of a specific linguistic category--we contrast those disorders selectively affecting verbs (action names) with those selectively affecting nouns (object names); (2) the impairment of a specific conceptual/semantic domain--we contrast disorders selectively affecting living beings with those preferentially affecting man-made artefacts. The hypothesis that different categories of knowledge may be closely intertwined with different sources of sensory-motor information, was substantially confirmed. The lesion preferentially encroached on the left frontal lobe when the category "verbs" was selectively affected; it involved the left temporal lobe and the posterior association areas when the category "nouns" was preferentially disrupted; it involved bilateral temporo-limbic structures and inferior temporal lobes when the category "living beings" was selectively disrupted; it usually encroached on the left fronto-parietal areas when man-made artefacts and body parts were preferentially affected. These data support the hypothesis that: (a) action schemata may critically contribute to the development of the semantic representation of verbs, (b) mechanisms of sensory integration may play an important role in establishing the semantic representation of nouns; (c) high-level visual processing and multi-modal sensory convergency may critically contribute to organising the semantic representation of living beings; (d) motor-kinaesthetic integration may play a leading role in developing the semantic representation of man-made artefacts.

Aphasia, Broca↗
PubMedDate not supplied

Apolipoprotein E genotype in sporadic early- and late-onset Alzheimer's disease.

The 84 isoform of apolipoprotein E (ApoE) has been proposed as a risk factor for Alzheimer's disease (AD), while the possible role of the epsilon2 allele in AD is controversial. We have studied the ApoE genotype in 38 patients with early-onset AD (EOAD) and in 43 patients with late-onset AD (LOAD). In the EOAD group we observed a significant increase of epsilon4 allele frequency as compared with normal controls, while there was a more than 3-fold decrease of epsilon2 allele frequency that did not reach statistical significance. In the LOAD group we found a highly significant increase of epsilon4 allele frequency as compared with normal controls, while there was a significant decrease of epsilon2 allele frequency. In both the EOAD and LOAD groups, no significant difference was observed between epsilon4 carriers and epsilon4 noncarriers as for age at disease onset, disease duration, and Mini-Mental State score at observation. However, in both EOAD and LOAD groups a statistical trend towards a longer disease duration was observed in epsilon4 carriers. In both the EOAD and LOAD groups, disease severity was compared in epsilon4 carriers versus epsilon4 noncarriers by means of analyses of covariance, with disease duration as covariate. No significant difference between epsilon4 carriers and epsilon4 noncarriers was observed in both EOAD and LOAD. The results of the present study confirm that epsilon4 allele seems to be associated with an increased risk for sporadic AD, while the significant decrease of epsilon2 allele frequency in the LOAD group supports the hypothesis of a possible protective role of epsilon2 allele in AD.

Age of Onset↗
PubMedDate not supplied

Predictors of cognitive decline in the early stage of probable Alzheimer's disease.

Several papers have attempted to find neurological and neuropsychological predictors of progression in Alzheimer's disease (AD) till now. Despite this quite large amount of works, different and not univocal conclusions have been reported in this field. Different study samples, different end-points and differences in statistical methods can explain much of the inconsistency in the results obtained. In our study, AD patients were examined in a very early stage of the disease to avoid any possible risk to examine subjects at different times of evolution. All the patients underwent an extensive neuropsychological test battery twice (baseline and follow-up) spaced out over about 1 year and were divided into two groups of fast decliners (FD) and slow decliners (SD) on the basis of their rate of decay at the MMSE score. Verbal memory tests, mental control abilities and attention-demanding tasks seem to play a pivotal role in distinguishing the two groups of subjects in the early stage of the disease. Moreover, FD patients show a worse performance than SD at the baseline in most of the cognitive domains explored. In conclusion, different subtypes of AD do exist and an important predictor of progression is represented by the severity of the cognitive impairment at the onset.

Aged↗
PubMedDate not supplied

Lack of impairments on leftward and rightward line extension tasks in neglect patients.

We asked 16 right-brain damaged patients with left unilateral neglect, 9 right-brain damaged patients without neglect and 11 healthy control subjects to bisect horizontal lines or to extend them rightward or leftward. Although in the line bisection task patients with neglect showed the typical rightward deviation of the subjective line midpoint, they did not show any significant difference when compared to the other two experimental groups in both rightward and leftward line extension tasks. These results suggest that neglect for the left side of space is usually observed in tasks requiring an automatic lateral orienting of attention, but not in tasks in which this lateral orienting is submitted to a continuous intentional control.

Agnosia↗
PubMedDate not supplied

[Homolateral and controlateral disturbances in the tactile discrimination of the hemispheric lesions].

Ten normal controls and 45 brain-damaged patients, affected by lesions of the right (N = 25) or of the left (N = 20) hemisphere were given a test of two points discrimination, in order to check the hypothesis of a different organization of the somesthetic function at the level of the dominant and of the minor hemisphere. Somatosensory thresholds were measured at the level of the back of the hands and of the back of the feet by means of a modified version of the Weber two-point aesthesiometer. When patients with lesions of the right and of the left hemisphere were compared the following results were obtained: --somatosensory thresholds were higher on the contralateral than on the ipsilateral side of the body in both groups of patients; --ipsilateral defects were found in about 20% of the brain-damaged patients, but no relationship was put in evidence between laterality of lesion and ipsilateral sensory defects.

Aphasia↗
PubMedDate not supplied

Progress and controversies in neuropsychology of memory.

In the first part of this paper we discuss some of the most important areas of progress and of controversy in the field of memory functions and of memory impairment. Three main issues are taken separately into account: (1) the fractionation of memory into a number of sub-systems and the relationships existing among these subsystems; (2) the main theories of amnesia and the mechanisms underlying memory disorders; (3) the main anatomoclinical forms of amnesia and the brain structures subserving various components of the amnesic syndrome. In the second part we shift from the basic research to the clinically oriented investigations, reporting the results of two studies that we have recently conducted on some aspects of memory disorders in dementia. In the first study we have shown that severity and qualitative aspects of amnesia can be used to distinguish the two most frequent clinical forms of dementia, namely the dementia of the Alzheimer's type (DAT) from the vascular forms of dementia. In the second study we have demonstrated that a fine grained analysis of memory impairment can help improving the most difficult differential diagnosis in this field, namely the distinction between DAT and depressive pseudo-dementia.

Alzheimer Disease↗
PubMedDate not supplied

[An experimental study of autotopagnosia (author's transl)].

One hundred and twenty patients with unilateral cerebral hemisphere damage (54 aphasics, 21 non-aphasic left and 45 right brain-damaged patients and 57 control subjects without cerebral lesions were given a battery of verbal and non-verbal tests of autotopagnosia, with the aim of studying the relationships between disorders of body schema and the side of the hemispheric lesion. A second aspect of our research consisted in understanding whether impairment in naming and pointing to body parts following verbal commands was really a specific symptom or if the same difficulty was found when patients were asked to name or to point to parts of objects other than the human body. Our results have shown that: 1) the aphasic patients are significantly more impaired than the non-aphasic patients on all the tests, non-verbal as well as verbal; 2) when results obtained on tests of naming and of pointing to parts of the human body were matched with results obtained on tests of naming and of pointing to parts of objects other than the human body, no difference could be demonstrated. These findings suggest that autotopagnosia is a nonspecific symptom, and that it does not find a satisfactory explanation in terms of "disorders of the body schema".

Adult↗
PubMedDate not supplied

Interictal psychopathology in temporal lobe epilepsy. The role of laterality of the epileptic focus.

The relationship between interictal psychopathology and laterality of the EEG focus in temporal lobe epilepsy was investigated by administering the Minnesota Multiphasic Personality Inventory (MMPI) to 37 epileptic patients, with an EEG focus lateralized to the right (N = 12) or left (N = 25) temporal lobe. T scores obtained on the various scales of the MMPI were used for evaluating incidence and degree of psychopathology. No relationship was observed between laterality of temporal lobe epilepsy and associated interictal psychopathology. The hypothesis that a temporo-limbic epileptic focus may interact with the characteristic organization of each cerebral hemisphere to induce different psychopathological traits is not supported by our data.

Adult↗
PubMedDate not supplied

[Disorders of autonomic responses to emotional stimuli in patients with unilateral hemispherical lesions].

The authors have studied in 31 patients affected by right (N = 12) or left (N = 19) hemispheric lesions and in 10 normal controls the autonomous response to emotional stimuli. Stimuli consisted of 3 short films, aiming to provoke respectively a negative emotional reaction, a positive emotional response or a non-emotional reaction. Galvanic skin response and heart rate were considered as the dependent variables of our research. Both normal controls and left brain-damaged patients were very influenced by the emotional nature of the stimuli and showed clear signs of activation of the sympathetic and para-sympathetic systems in front of emotional films. By contrast, right brain-damaged patients were not influenced by the emotional or non-emotional nature of the stimuli and showed neither a clear galvanic skin response nor a significant decrease of heart rate in front of emotional films.

Brain Diseases↗
PubMedDate not supplied

[Visuo-constructive disorders in right and left brain-damaged patients (author's transl)].

There seems to be some lack of agreement between clinical and experimental findings pertaining to the neurodynamic mechanisms of visuo-constructive disabilities in right and left brain-damaged patients. Clinical studies have revealed qualitative differences between drawing disabilities of right and left hemispheric origin, while experimental data suggest that the same mechanism underlies both types of constructional disorder. In order to reconcile these conflicting findings, the existence of "nuclear" impairment and more "peripheral" disturbances in constructional apraxia is suggested. Nuclear impairment seems to consist of a visuo-perceptive disorder independent of the hemispheric locus of lesion; peripheral disturbance could be different in right and left brain-damaged patients, motor and symbolic disorders being typical of left-sided lesions while unilateral spatial neglect would be characteristic of right hemispheric injuries.

Brain↗