Biomedical subjects

C Caltagirone

Publications and source records attributed to C Caltagirone.

At least 109 records · Page 6Linked to original sources

PubMed1995

Explicit memory and repetition priming in dementia: evidence for a common basic mechanism underlying conscious and unconscious retrieval deficits.

The present study was designed to assess performance of Alzheimer's (AD) and Multi-infarct (MID) demented patients on the explicit and implicit versions of two memory tasks, namely Word-Stem Completion and Word-Pair Learning. Consistently with previous studies, the AD patients were deficient on the explicit and implicit versions of both tasks. In MID patients, a dissociation emerged between normal implicit and deficient explicit Word-Stem Completion. Two multiple regression analyses were performed to evaluate patients' ability on measures of lexical-semantic competence, explicit memory, and global intellective efficiency in predicting level of repetition priming. The results demonstrate a close association between explicit and implicit memory performance in AD patients but no relation between repetition priming level and measures of lexical-semantic competence or general intelligence. Overall, the results of the present study do not support previous conceptualizations suggesting that a breakdown in the structure of semantic memory is at the root of deficient priming in demented patients. Alternative interpretations of the deficient repetition priming effect in dementia, based on a common mechanism underlying conscious and unconscious retrieval deficits, are discussed.

Aged↗

PubMed1995

Short-term memory in persons with intellectual disabilities and Down's syndrome.

The present study was designed to investigate verbal and spatial short-term memory abilities in persons with Down's syndrome (DS) and intellectual disability (ID) of different aetiology. For this purpose, we compared performances of DS (n = 15; mean mental age = 5.2 years; SD = 1.2 years; mean chronological age = 16.6 years; SD = 2.9 years) and ID subjects (n = 14; mean mental age = 5.8 years; SD = 2.1 years; mean chronological age = 16.4 years; SD = 2.5 years) with those of normally developed subjects matched for mental age (n = 24) on tasks of forward and backward immediate recall of verbal and spatial sequences. Our results are discussed in the light of the Working Memory model developed by Baddeley (1986, 1990). Altogether, our data documents a deficit of verbal and spatial backward spans in persons with DS. The deficit seems to be specific for this particular aetiology group, confirming the hypothesis that ID is not a uniform condition, characterized by an undifferentiated delay of the cognitive development, but rather that it is characterized by a deficit in a complex cognitive system in which some cognitive abilities can be disrupted more than others (Detterman 1987; Vicari et al. 1992).

Adolescent↗

PubMed1995

Involvement of the healthy hemisphere in recovery from aphasia and motor deficit in patients with cortical ischemic infarction: a transcranial Doppler study.

Activation of areas of the health hemisphere seems to play a role in functional recovery from stroke. We studied cerebral blood flow changes during motor and mental activity in patients with cortical ischemic lesions. We simultaneously measured blood flow velocity in the two middle cerebral arteries of 45 patients with single cortical ischemic lesions and good functional recovery and of 16 healthy controls by means of bilateral transcranial Doppler ultrasonography during a 2-minute sequential thumb-to-finger opposition task, alternately performed with the right and left hands, and during a 1-minute word-fluency task. Twenty-five patients had left cortical lesions, 12 with previous motor deficit alone and 13 with associated motor deficit and Broca's aphasia. Twenty patients had right cortical lesions with previous motor deficit. With respect to baseline values, the increase of flow velocity in the middle cerebral artery contralateral to the hand performing the motor task was comparable in controls and patients, regardless of the side of the lesion and the hand (normal or recovered) involved in the task. During movement of the recovered hand, the increase of flow velocity in the ipsilateral middle cerebral artery was significantly greater (p < 0.001, two-way ANOVA) than the increase during movement of the normal hand in both controls and patients. During performance of the word-fluency task, the increase of flow velocity in the left middle cerebral artery was comparable in controls and patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗

PubMed1994

Visual repetition priming for words relies on access to the visual input lexicon: evidence from a dyslexic patient.

In this study we tested the hypothesis that visual repetition priming for words depends upon the accessibility of lexical units in the visual input lexicon. For this purpose, we investigated a dyslexic patient, A.M., whose neuropsychological performances suggested an impaired access to the lexical route of reading. According to the predictions, Experiments 1 and 2 demonstrated deficient priming in tests involving the visual presentation of words (Word Identification and Stem Completion). In Experiment 3, we demonstrated that A.M.'s deficient priming was specific for visually presented words, in that the auditory presentation elicited a normal priming effect (auditory Stem Completion). These data are discussed in the light of a theoretical framework suggesting a fractionation of the modalities by which repetition priming can be elicited, each mediated by a particular memory subsystem.

Attention↗

PubMed1994

Bilateral simultaneous assessment of cerebral flow velocity during mental activity.

The purpose of this study was to assess the potential of transcranial Doppler (TCD) ultrasonography for detecting selective changes in cerebral blood flow velocity during mental activity. Mean flow velocity was continuously and simultaneously measured in the right and left middle cerebral arteries in 26 healthy right-handed young subjects at rest and during performance of verbal and visual-imaging mental tasks. These two mental tasks produced significantly different effects on the right and left sides: the verbal task produced a higher increase of flow velocity (mean absolute difference above baseline +/- SD) with respect to the basal values in the left than in the right middle cerebral artery (5.56 +/- 3.8 cm/s vs 1.25 +/- 3.1 cm/s); the visual-imaging task was accompanied by a higher increase in the right than in the left middle cerebral artery (3.92 +/- 3.3 cm/s vs 1.52 +/- 3.1 cm/s)--analysis of variance (ANOVA) three-fold interaction side of recording x task x condition, F = 25.67, p < .0001). Heart rate, blood pressure, and skin conductance showed comparable increases during performance of both mental tasks. Respiratory activity showed no modification during the mental activity with respect to the rest phase. These results demonstrate the possibility of delivering specific functional information via bilateral TCD and suggest wider utilization of this noninvasive technique in neuropsychological studies.

Adult↗

PubMed1994

Verbal and spatial memory spans in Alzheimer's and multi-infarct dementia.

This study aimed to explore verbal and spatial memory spans in Alzheimer's (AD) and multi-infarct (MID) demented patients. For this purpose, we administered the forward and backward versions of the Digit Span and of the Corsi test to 18 AD, 18 MID and 26 controls. Results revealed a normal forward verbal span but reduced backward verbal and forward and backward spatial spans in both demented groups. These data are discussed in the light of the Working Memory model. It is argued that the normal verbal forward span is sustained by a normally functioning Articulatory Loop. The deficient processing resources of the Central Executive, on the other side, are responsible for the reduced extension of the other memory spans. The possible anatomical substrate of short-term memory impairment in dementia, as well as alternative interpretations of memory span performance in demented patients are discussed.

Adult↗

PubMed1994

Quantitative EEG evaluation in normal elderly subjects during mental processes: age-related changes.

Computerized EEG study was performed on 39 healthy elderly subjects (50-90 years), divided into two cohorts of increasing age (old, older) and on a group of 21 young controls. The EEG was recorded at rest, with eyes closed (EC) and during blocking reaction (BR), fixation (FIX) and mental arithmetic (MA) tasks. At rest with EC, the only significant variation was an increase of beta 1 relative power in old subjects which was positively correlated with age. During the performance of the mental tasks, in the elderly population when compared to young controls, the slow activity decreased slightly or was not significantly modified, while the alpha reactivity progressively decreased, showing a negative correlation with age in the older group. Beta 2 increased significantly in elderly subjects during BR and FIX but such change was less consistent with increasing age. Data show that at rest, the EEG in the elderly population differs only from that of young controls by showing a more pronounced fast activity, while only during mental processes is it possible to evidence changes that can be utilized as physiological "markers" of normal aging.

Adult↗

PubMed1993

Basic mechanisms of constructional apraxia in unilateral brain-damaged patients: role of visuo-perceptual and executive disorders.

The basic mechanisms of constructional apraxia (CA) are still a matter of debate. In this study we assessed the possible relationships between CA and performance on tasks assessing visual perception, low-level motor skill, manipulo-spatial ability, and general intellective efficiency in samples of healthy subjects, right-brain-damaged (RBD) and left-brain-damaged (LBD) patients. Multiple regression analyses, performed separately for the three groups, demonstrated that efficiency in perceiving the model as a whole is the factor mainly related to drawing performance of normal subjects. In the RBD group, instead, a disorder of the manipulo-spatial ability seems to play the most important role in producing CA. As for the LBD group, the most relevant finding is that patients drawing with the left hand are significantly more impaired than patients using the right hand and than control subjects. These results are discussed in relation to various hypotheses so far advanced to account for basic mechanisms of CA in unilateral brain-damaged patients.

Aged↗

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

Activation of healthy hemisphere in poststroke recovery. A transcranial Doppler study.

BACKGROUND AND PURPOSE: The possible involvement of the healthy hemisphere in functional recovery in stroke hemiplegia is still controversial. This study of patients who had suffered ischemic stroke assessed circulatory changes in the healthy hemisphere by transcranial Doppler ultrasonography during opposition exercise of fingers that had recovered movement. METHODS: Measurements of flow velocity in the middle cerebral arteries were recorded in 12 recovered hemiplegic stroke patients and 12 healthy sex- and age-matched control subjects during a 2-minute sequential thumb-to-finger opposition task, alternatively performed with normal and recovered fingers. The effects of the motor task on heart rate, blood pressure, and end-tidal PCO2 were also evaluated. RESULTS: With respect to the basal values, a comparable increase of flow velocity (%mean +/- SD) in the contralateral middle cerebral artery occurred in patients during movement of normal (9.7 +/- 2.7%) and recovered fingers (10.4 +/- 5.1%) and in controls (11.3 +/- 4.9%). However, in the middle cerebral artery ipsilateral to the hand performing the motor task, the increase of flow velocity was significantly higher (P < .001, two-way analysis of variance) during movement of the recovered hand in patients (10.5 +/- 4.6%) than during the movement of the normal hand in both patients (1.7 +/- 3.7%) and controls (1.8 +/- 4.5%). No significant difference of changes in heart rate, blood pressure, and end-tidal PCO2 was observed for patients or normal control subjects during the various phases of the study. CONCLUSIONS: Our data suggest that activation of the healthy hemisphere contributes toward functional recovery of motor deficit after stroke and confirms the ability of transcranial Doppler ultrasonography to correlate cerebral artery flow dynamics with selective cerebral activation.

Aged↗

PubMed1993

Differential rates of forgetting from long-term memory in Alzheimer's and multi-infarct dementia.

In this study we explored the rate of forgetting from long-term memory in Alzheimer's (AD) and multi-infarct (MID) dementia. For this purpose, we administered to 15 AD, 15 MID, and 22 control subjects two tasks exploring, respectively, long-term verbal and long-term visuo-spatial memory. The absolute rate of forgetting in both tasks was computed as the difference between immediate and delayed recall of memorandum. Since level of immediate recall was significantly different between groups, a proportional rate of forgetting (percentage of memorandum lost passing from immediate to delayed recall) was computed for each patient. In the verbal task (Rey's 15 words) AD patients displayed significantly larger absolute and proportional rates of forgetting than MID and control subjects. In the spatial task (Corsi block supraspan), the absolute rate of forgetting was only marginally different between groups. Nevertheless, AD patients demonstrated a larger proportional rate of forgetting than MID and normal subjects. These results point out an exalted decay of information from long-term memory store in AD patients. In the light of previous data (Corkin et al., 1984; Kopelman, 1985) we propose that long-term memory deficits in AD is due, at least in part, to an abnormal forgetting of information within the first few minutes following acquisition. Information still present in the subsequent period (10 min to several days) is retained normally. The normal rate of forgetting in MID patients, further, suggests different mechanisms underlying memory disorders in vascular and degenerative dementias.

Aged↗

PubMed1992

Cognitive profiles in adolescents with mental retardation.

Cognitive profiles of performance were obtained from a selected group of adolescent subjects with mental retardation (MR) (n = 32; mean age: 15.4 years, S.D. = 3.7) by means of an ad hoc neuropsychological battery. On the basis of each subject's IQ, the experimental sample was divided into three homogeneous subgroups (severely, moderately and mildly retarded) and cognitive performances obtained in the battery tests were compared. Subsequently, in order to clarify the qualitative aspects of MR, the cognitive patterns of subjects with the same IQ and chronological age were examined. Altogether, from a neuropsychological point of view, the results of this study seem to support the hypothesis that MR is a heterogeneous condition of cognitive deficits (some abilities are better preserved than others) and indicate that a set of multiple tests exploring single cognitive functions is needed in order to describe cognitive profiles in MR.

Adolescent↗

PubMed1992

Lateralization of the epileptogenic focus by computerized EEG study and neuropsychological evaluation.

The localization of the epileptogenic focus relies on different factors. In patients with partial seizures, asymmetries in EEG background activity were measured by a statistical evaluation of spectral data. Neurophysiological results were compared with neuropsychological findings and MRI. Fifteen of 22 patients showed asymmetries in EEG background activity. The most prominent abnormality was a statistically significant increase of slow activity observed in 59% of cases. Delta asymmetry coincided with the site of lesions, evidenced by MRI, in 83% of patients; with the site of decreased beta activity in 60% and with the maximum level of spiking activity in 58% of cases. Neuropsychological tests showed a lateralization of the hemispheric function which coincided with delta asymmetry in 33% of patients. These results suggest that the EEG background activity, when compared with other parameters, may represent a useful method in lateralizing the epileptogenic focus.

Adolescent↗

PubMed1991

Comparison of neuropsychological, MRI and computerized EEG findings in a case of prosopoagnosia.

We present the case of a patient suffering from prosopoagnosia (PA). The MRI, performed at the onset of the disease, showed a lesion, strictly confined to the right temporo-occipital region; whereas the computerized EEG documented a functional impairment of the posterior regions of both hemispheres. A control performed two months later indicated a partial recovery of the neuropsychological deficit coupled with an improvement of EEG abnormalities, which was more prominent on the left side. The usefulness of functional studies in order better to comprehend the anatomical substrates of PA and their prognostic value are briefly discussed.

Adult↗

PubMed1990

Cognitive functions in adult Down's syndrome.

Cognitive profiles of performances were obtained from a selected group of adult Down syndrome (DS) subjects (n = 20; mean age: 34.5 years; s.d.: 7.7) by means of an ad hoc neuropsychological battery. With the aim of examining, from a neuropsychological point of view, the modifications that increasing age produces in this group of patients, cognitive performances of younger DS subjects (mean age: 28 years; s.d.: 4.77) were compared with analogous performances obtained by the older ones (mean age: 39.8 years; s.d.: 5.11). Subsequently, to clarify qualitative aspects of cognitive patterns in the subgroups of young and old DS subjects, two different groups of control patients were utilised. Neuropsychological data collected from a group of adult mentally retarded subjects were compared with cognitive performances demonstrated by young DS subjects, while the old group of DS subjects was analyzed in comparison with a group of patients affected by initial form of Alzheimer disease (AD). Altogether, the results of our study do not seem to support, from a neuropsychological point of view, the hypothesis that mental decline observed in DS subjects reproduces the cognitive patterns of impairment observed in AD patients.

Adult↗

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

Defective concept formation in parkinsonians is independent from mental deterioration.

An extensive neuropsychological battery (the Mental Deterioration Battery) was utilized to distinguish, within a sample of 24 idiopathic Parkinsonians, those showing signs of diffuse mental deterioration (n = 9) from those without deterioration (n = 15). Performances of control subjects on a wide range of tests exploring mnesic, visuo-constructive, linguistic and general intellectual functions (n = 21) did not differ from analogous performances of Parkinsonians without signs of diffuse mental deterioration. The Wisconsin Card Sorting Test was then used to verify the hypothesis that a selective impairment of cognitive functions subsumed by the integrity of frontal lobes could be demonstrated in Parkinsonian patients. Our results provide evidence that in this task, defective performances are obtained by Parkinsonians and even by patients without signs of diffuse cognitive impairment. These findings seem to confirm that a deficit in concept formation, maintenance and shifting is largely independent of the dementia frequently noticed in Parkinson's disease.

Aged↗

PubMed1989

Differential aspects of cognitive impairment in patients suffering from Parkinson's and Alzheimer's disease: a neuropsychological evaluation.

Neuropsychological profiles of cognitive impairment demonstrated by a group of Parkinson patients and by a group of Alzheimer patients both affected by a comparable level of mental deterioration were obtained by means of a neuropsychological battery. The results pointed out differential patterns of cognitive impairment exhibited by the two pathological groups. Particularly, Alzheimer's patients appear to be mainly impaired in mnesic functions, while Parkinsonian subjects show a pattern of performances indicative of a prevalent impairment of the functions underlied by frontal lobes. These data are in agreement with the hypothesis that different anatomical-functional cerebral structures are mainly involved in determining cognitive deterioration in the two diseases.

Alzheimer Disease↗