Biomedical subjects

S F Cappa

Publications and source records attributed to S F Cappa.

At least 55 records · Page 3Linked to original sources

PubMed1996

Persistent post-traumatic retrograde amnesia: a neuropsychological and (18F)FDG PET study.

We report the case of a 48-year old woman who, after a severe closed head injury, developed a severe and persistent disruption of retrograde memory, associated with a mild impairment of learning abilities. The patient's dense amnesia spared only the childhood period and included both explicit memory (autobiographical and semantic) and procedural skills. Because of her partially spared learning ability and intact language, intensive training by family members resulted in the reacquisition and retention of many autobiographical events and of some skills she had lost after the accident. Brain CT scan and MRI were normal; a PET study with (18F)FDG revealed a significant bilateral reduction of metabolism in the hippocampus and anterior cingulate cortex, suggesting a role for these structures in memory for past events.

Amnesia↗

PubMed1996

The Mini-Mental State Examination in Alzheimer's disease and multi-infarct dementia.

The aim of this study was to compare the performances on each item of the Mini-Mental State Examination (MMSE) of patients with Alzheimer's disease (AD) and multi-infarct dementia (MID). In order to identify the items that could better distinguish the two groups of patients, 70 AD and 31 MID patients matched for disease severity, age, and education were evaluated. The scores of the 101 patients on each of the MMSE items were entered into a principal component factor analysis using varimax rotation, and two main components were derived. Component 1 was probably representative of recently acquired information, whereas component 2 represented educational level. A score summing the items that loaded on component 1 and the recall item was calculated to generate a measure of episodic memory. Performing analysis of variance and covarying for age and education revealed that this score was statistically different in the two groups, with AD patients having lower values. The data suggest that the MMSE may demonstrate a pattern of impairment of memory that differs between AD and MID. Possible explanations of this finding should take into account the different neuroanatomical impairments and the different degrees of motivation, due to depression or attentional deficits, toward external stimuli.

Aged↗

PubMed1996

Executive dysfunction in early Alzheimer's disease.

Twenty five patients with probable mild Alzheimer's disease were assessed for deficits in executive functioning and the impact of these deficits on performance in other neuropsychological domains. The Wisconsin card sorting test, the release from proactive interference paradigm, the verbal fluency test, and the Stroop test were adopted to classify patients with (AD+) and without (AD-) executive deficits. Seven of the patients showed an impairment in executive function (AD+), defined as a performance below the cut off score in at least two of these tests. There were no significant differences in clinical assessments, demographic features, or other cognitive functions between patients. Executive dysfunction may be an early additional feature in a subgroup of patients with mild Alzheimer's disease. Impairment on frontal lobe tests does not seem to be related to the severity or duration of disease, or to a different pattern of impairment in other cognitive domains.

Aged↗

PubMed1995

Different neural systems for the recognition of animals and man-made tools.

Using positron emission tomography, we mapped brain activity in normal volunteers during the recognition of visual stimuli representing living (animals) and non-living (artefacts) entities. The subjects had to decide whether pairs of visual stimuli were different representations of the same object, or different objects. Animal recognition was associated with activations in the inferior temporo-occipital areas, bilaterally, whereas artefact recognition engaged a predominantly left hemispheric network, involving the left dorsolateral frontal cortex. These findings, which concur with clinical observations in neurological patients, provide in vivo evidence for a fractionation of the neural substrates of semantic knowledge in man.

Adult↗

PubMed1995

Release from proactive interference in early Alzheimer's disease.

The study analyses the performance of 22 mild Alzheimer's disease (AD) patients on the Release from Proactive Interference (RPI) paradigm with the aim to investigate the relationship of RPI with frontal function. Twenty-one normal elderly subjects, age and education matched, constituted the control group. Patients with AD were found to recall less words on each trial of the RPI than did the controls. The analysis of Proactive Interference (PI) and Release from PI, in AD patients, by using Anova (trial x group), showed a significant effect of trial and group but not a group by trial interaction. These results indicate a similarity between the performance of AD patients and normal controls on the Release from Proactive Interference paradigm. Despite the similar pattern of performance, AD patients were significantly inferior to normal controls with regard to global performance level. The AD patients' scores on "frontal lobe" tests were correlated with an index of RPI (shift condition index). The only significant result was with the number of categories on the Wisconsin Card Sorting Test, suggesting a weak correlation between RPI and "frontal lobe" function.

Aged↗

PubMed1995

Semantic memory in Alzheimer's disease: an analysis of category fluency.

In order to study the strategies of access to semantic knowledge and the status of semantic representation, we analyzed the performance in a semantic fluency task (Animal naming) of 70 patients with probable Alzheimer's disease (AD), including 40 mild AD patients and 30 moderate-severe AD patients, and 35 matched elderly normal control subjects. The total amount of words produced, their lexical frequency, the number and type of errors, as well as the presence and the type of clusters of related animal names were recorded. AD patients produced less animal exemplars than controls. In addition to a lower total number of clusters, the AD patients showed a strong limitation in clusters' selection, producing a limited number of different clusters. While normal subjects produced several different clusters, only farm animals were clustered by AD patients. When the total amount of words was considered, the mean lexical frequency was higher in the AD group. On the other hand, the words produced within clusters were comparable to terms of lexical frequency and number. These data confirm the impairment of AD patients in category fluency tasks, and suggest a degradation of semantic knowledge as the most likely underlying mechanism.

Aged↗

PubMed1995

Intramodal somaesthetic recognition disorders following right and left hemisphere damage.

A dissociation between apperceptive and associative processing after right and left hemisphere damage, respectively, has been suggested for visual, auditory and visuo-tactile matching tasks. This study was aimed at testing for this dissociation in a purely somaesthetic task. Forty consecutive patients with recent right and left hemispheric vascular lesions and 10 normal controls were studied. The groups were compared on two intramodal somaesthetic matching tasks, consisting of either meaningless shapes (apperceptive recognition) or meaningful objects (associative recognition). In normal controls, no significant difference was found either between the two tests, indicating a similar degree of difficulty, or between hands. An analysis of variance indicated a differential impairment of the two hemisphere-damaged groups on the two tests in comparison with normal controls. Right hemisphere lesions impaired the apperceptive, but not the associative, task, while the reverse occurred after left hemisphere lesions. This double dissociation between side of hemispheric lesion (right and left) and level of recognition impairment (apperceptive and associative) extends the results reported for other sensory modalities to intramodal tactile recognition matching.

Aged↗

PubMed1994

Identification of the central vestibular projections in man: a positron emission tomography activation study.

The cerebral representation of space depends on the integration of many different sensory inputs. The vestibular system provides one such input and its dysfunction can cause profound spatial disorientation. Using positron emission tomography (PET), we measured regional cerebral perfusion with various vestibular stimulations to map central vestibular projections and to investigate the cerebral basis of spatial disorientation. We showed that the temporoparietal cortex, the insula, the putamen, and the anterior cingulate cortex are the cerebral projections of the vestibular system in man and that the spatial disorientation caused by unilateral vestibular stimulation is associated with their asymmetric activation.

Adult↗

PubMed1994

Pure anomia with spared action naming due to a left temporal lesion.

We report the case of a patient who, after surgical ablation of an angioma in the depth of the left temporal lobe, developed a highly selective impairment of naming. A detailed investigation allowed to exclude a disorder of visual recognition or of semantic memory, and indicated the output lexicon as the most probable site of impairment. Grammatical class effects, with superior action naming, and a high consistency within and across output modalities further characterized the patient's performance. Together with some other recently reported cases, this patient suggests a correlation between temporal lobe lesions outside Wernicke's area and output lexicon disorders. A relatively spared action naming seems to be a characteristic feature of this pattern of impairment.

Adult↗

PubMed1994

Frontal dysfunction in early Parkinson's disease.

Recent studies have suggested that patients with Parkinson's disease (PD) share many of the behavioral deficits found following lesions to the pre-frontal cortex. We assessed the performance of a group of 22 mildly impaired, not-demented parkisonians (I or II Hoehn & Yahr stage) in a test of classification and recall of pictures of familiar objects, which has been demonstrated to be sensitive to frontal damage in patients with unilateral cerebral excision. Parkinsonians utilized fewer categories than normal controls for object classification, while no significant difference was found in the immediate and delayed recall scores. These results support the contention that a subclinical dysfunction of frontal type may be present even in the early stages of PD. A subanalysis of the data suggests that this dysfunction could possibly be aggravated by anticholinergic drugs.

Adult↗

PubMed1993

Evidence of multiple memory systems in the human brain. A [18F]FDG PET metabolic study.

Patients with global amnesia of different aetiologies (n = 11), and patients with probable Alzheimer's disease of recent onset and mild to moderate severity (n = 18) underwent extensive neuropsychological examination, which included the evaluation of multiple components of memory, and a measurement of regional cerebral glucose metabolism with [18F]fluoro-deoxyglucose ([18F]FDG) and PET. In the neuropsychological tests, both global amnesia and Alzheimer's disease patients had impaired episodic long-term memory, while deficits of short-term, semantic and implicit memory were present only in Alzheimer's disease. When local metabolic rates for glucose were compared with values from age- and education-matched normal controls, a common pattern of bilateral hypometabolism was present in the hippocampus, cingulate and frontal basal cortex of both global amnesia and Alzheimer's disease patients. On the other hand, significant hypometabolism was found in the thalamus in only global amnesia, and in the frontal, parietal and temporal associative cortex in only Alzheimer's disease. The results of a multivariate regression analysis of test scores with metabolic data indicated that different clusters of cerebral areas were associated with each of the main components of memory function. These data are in agreement with 'neural network' models of the neural basis of cognition, according to which complex functions are subserved by multiple interconnected cortical and subcortical structures.

Aged↗

PubMed1993

Serial study of neuropsychological performance and gadolinium-enhanced MRI in MS.

Many multiple sclerosis patients show cognitive decline, although no definite correlation between brain demyelination at MRI and neuropsychological performance has been found so far. We submitted a group of nine relapsing-remitting, mildly disabled patients to both serial gadolinium-DTPA enhanced MRI and neuropsychological evaluation in a follow up period of three months. Despite the great variability in acute lesions' load, no overall decline in test, performance was found. Furthermore, in selected cases whose test scores declined at follow up, no concordance with the new lesion load was found.

Adult↗

PubMed1993

Crossed aphasia: a PET follow up study of two cases.

Two cases of aphasia after right hemispheric stroke in right handed patients are described. The first patient had a severe mixed transcortical aphasia, apraxia and neglect after a lesion involving the right lenticular nucleus and periventricular white matter; aphasia was still present after three months. The second patient had a mild, transient fluent aphasia after a small right hemispheric periventricular lesion. Studies with [18F]FDG and positron emission tomography (PET) showed functional depression extending to the structurally unaffected left hemisphere in both patients in the acute stage. After three months, in the patient with persistent aphasia, metabolism was still reduced in the right hemisphere, with some recovery of hypometabolism on the left, while metabolic values had returned to normal in the patient with full language recovery. A close parallelism between glucose metabolism and clinical course in crossed aphasia is shown, as well as the presence of a functional involvement of the structurally unaffected left hemisphere in the acute stage.

Aged↗

PubMed1992

The neuropsychological consequences of HIV infection in drug addicts.

The occurrence of neuropsychological impairment in asymptomatic, HIV-positive individuals is controversial. In the present study we compared the performance of three groups of chronic intravenous drug abusers (HIV negative, asymptomatic HIV positive, AIDS) on a battery of neuropsychological tests. While the AIDS group was significantly impaired, no difference was found between HIV negative and HIV positive asymptomatic subjects on any measure. This finding is in agreement with the results of studies of homosexual and bisexual subjects, indicating that the presence of HIV infection in the asymptomatic stage does not carry an added risk of cognitive impairment in drug addicts.

Acquired Immunodeficiency Syndrome↗

PubMed1992

Metabolic impairment in human amnesia: a PET study of memory networks.

Human amnesia is a clinical syndrome exhibiting the failure to recall past events and to learn new information. Its "pure" form, characterized by a selective impairment of long-term memory without any disorder of general intelligence or other cognitive functions, has been associated with lesions localized within Papez's circuit and some connected areas. Thus, amnesia could be due to a functional disconnection between components of this or other neural structures involved in long-term learning and retention. To test this hypothesis, we measured regional cerebral metabolism with 2-[18F]fluoro-2-deoxy-D-glucose ([18F]FDG) and positron emission tomography (PET) in 11 patients with "pure" amnesia. A significant bilateral reduction in metabolism in a number of interconnected cerebral regions (hippocampal formation, thalamus, cingulate gyrus, and frontal basal cortex) was found in the amnesic patients in comparison with normal controls. The metabolic impairment did not correspond to alterations in structural anatomy as assessed by magnetic resonance imaging (MRI). These results are the first in vivo evidence for the role of a functional network as a basis of human memory.

Adult↗

PubMed1991

Neuropsychological assessment in multiple sclerosis: a follow-up study with magnetic resonance imaging.

Nineteen moderately impaired patients with clinically definite multiple sclerosis and an initially relapsing-remitting course were included in a neuropsychological and magnetic resonance imaging (MRI) follow-up study. The average test/re-test interval was about 2 years. The neuropsychological findings were indicative of a very mild overall impairment; the patients, as a group, showed no evidence of cognitive deterioration in the follow-up period. A numerical estimation of the severity of cerebral demyelination shown by MRI did not indicate a significant change. No correlation between cognitive performance variations and MRI changes was found.

Adult↗

PubMed1991

Somesthetic-visual matching disorders in right and left hemisphere-damaged patients.

Forty-nine patients with recent right (RHD) and left (LHD) hemispheric vascular lesions were compared on a task of somesthetic-visual matching of meaningful objects and of meaningless shapes. A selective impairment for shapes was found in RHD subjects, while LHD patients were impaired in object matching. This double dissociation conforms to the classical distinction between apperceptive and associative agnosia, and extends to the somesthetic modality the "double dissociation" between left and right hemispheric lesions and associative and apperceptive recognition disorders, which has been found in other modalities of agnosia.

Adult↗

PubMed1991

Visual and nonvisual neglect after unilateral brain lesions: modulation by visual input.

A spatial exploratory task was given to 110 patients with unilateral brain lesions [66 right brain-damaged (RBD) patients and 44 left brain-damaged (LBD) patients] in two conditions, with and without the aid of vision. Exploratory deficits mainly involved the contralesional half-space and were most frequently associated with right brain damage. A double dissociation was found between the visual and the nonvisual conditions of the task; selective impairments in the visual and in the nonvisual condition were associated with the presence and the absence of visual field deficits, respectively. The suggestion is made that discrete "visual" and "tactile-kinesthetic" spatial representational systems are involved in exploration of extrapersonal space. A further distinction is made between input and output spatial system. The association between visual field deficits and visual neglect is explained in terms of the impairment of an input visuospatial component, which feeds an output component involved in spatial exploration. Finally, the ambiguous nature of the visual field deficits in neglect patients is discussed and the suggestion is made that an attentional modality-specific nonsensory component may be present.

Brain Damage, Chronic↗