Biomedical subjects

C Caltagirone

Publications and source records attributed to C Caltagirone.

At least 73 records · Page 4Linked to original sources

PubMed2000

Time-dependent activation of parieto-frontal networks for directing attention to tactile space. A study with paired transcranial magnetic stimulation pulses in right-brain-damaged patients with extinction.

Tactile extinction has been interpreted as an attentional disorder, closely related to hemineglect, due to hyperactivation of the unaffected hemisphere, resulting in an ipsilesional attentional bias. Paired transcranial magnetic stimulation (TMS) techniques, with a subthreshold conditioning stimulus (CS) followed at various interstimulus intervals (ISIs) by a suprathreshold test stimulus (TS), are useful for investigating intracortical inhibition and facilitation in the human motor cortex. In the present work, we investigated the effects of paired TMS over the posterior parietal and frontal cortex of the unaffected hemisphere in a group of eight right-brain-damaged patients with tactile extinction who were carrying out a bimanual tactile discrimination task. The aim of the study was to verify if paired TMS could induce selective inhibition or facilitation of the unaffected hemisphere depending on the ISI, resulting, respectively, in an improvement and a worsening of contralesional extinction. In addition, we wanted to investigate if the effects of parietal and frontal TMS on contralesional extinction appeared at different intervals, suggesting time-dependent activation in the cortical network for the processing of tactile spatial information. Paired TMS stimuli with a CS and a TS, separated by two ISIs of 1 and 10 ms, were applied over the left parietal and frontal cortex after various intervals from the presentation of bimanual cutaneous stimuli. Single-test parietal TMS stimuli improved the patients' performance, whereas paired TMS had distinct effects depending on the ISI: at ISI = 1 ms the improvement in extinction was greater than that induced by single-pulse TMS; at ISI = 10 ms we observed worsening of extinction, with complete reversal of the effects of single-pulse TMS. Compared with TMS delivered over the frontal cortex, parietal TMS improved the extinction rate in a time window that began earlier. These findings shed further light on the mechanism of tactile extinction, suggesting relative hyperexcitability of the parieto-frontal network in the unaffected hemisphere, which is amenable to study and modulation by paired TMS pulses. In addition, the results show time-dependent processing of tactile spatial information in the parietal and frontal cortices, with a bimodal distribution of activity, at least in the attentional network of the unaffected hemisphere.

Aged↗

PubMed2000

Demyelinating plaques in relapsing-remitting and secondary-progressive multiple sclerosis: assessment with diffusion MR imaging.

BACKGROUND AND PURPOSE: Conventional MR imaging does not provide specific information that can be reliably associated with the pathologic substrate and clinical status of patients with multiple sclerosis (MS). Our goals were 1) to determine whether the orientationally averaged water diffusion coefficient ( ) can be used to distinguish between plaques of different severity in these patients and 2) to assess possible correlations between values and disease duration, Expanded Disability Status Scale (EDSS) score, and signal intensity on T1-weighted MR images. METHODS: Twenty patients (10 with relapsing-remitting MS and 10 with secondary-progressive MS) and 11 healthy volunteers underwent a combined conventional and diffusion-weighted MR study of the brain. , a parameter that is proportional to the trace of the diffusion tensor, was computed by averaging the apparent diffusion coefficients measured in the x, y, and z directions. measurements were obtained for selected areas of white matter plaques. Differences in among the three groups were tested using analysis of variance. RESULTS: was significantly higher (1.445 +/- 0.129 x 10(-3) mm2/s) in secondary-progressive lesions than in relapsing-remitting lesions (0.951 +/- 0.08), and both values were higher than in normal white matter (0.732 +/- 0.02). There was a significant negative correlation between and the degree of hypointensity on T1-weighted images, and a positive correlation between and both EDSS score and disease duration. CONCLUSION: Our findings suggest that is useful for distinguishing MS lesions of different severities, which are associated with different degrees of clinical disability.

Adolescent↗

PubMed2000

Recognition of facial expressions of emotions in school-age children: the intersection of perceptual and semantic categories.

UNLABELLED: Recognition of the facial expressions of emotions is a critical communicative system early in development and continues to play an important role throughout adulthood. In the past, the results of developmental studies of emotional facial recognition have often conflicted. The present study was designed to examine the development of emotional facial recognition in a large sample of school-aged children (n = 120, ages 5-10y). In particular, we investigate whether emotion categories, i.e., those based on the visual spatial parameters of facial expression, develop in a similar fashion to those that also recruit lexical knowledge of emotion terms. We have found two distinct patterns of development and we suggest that these different profiles are a consequence of the very different cognitive abilities that they recruit. CONCLUSION: Emotion cognition is a variegated domain which is differentially related to such areas of cognition as visuo-spatial and lexical semantic abilities.

Age Distribution↗

PubMed1999

Patterns of cerebrovascular reactivity in patients with carotid artery occlusion and severe contralateral stenosis.

There is evidence suggesting that among other factors, an alteration in cerebral hemodynamics plays a relevant role in the occurrence of strokes in patients with carotid disease. The purpose of this study was to investigate patterns of cerebrovascular reactivity in patients with internal carotid occlusion and severe contralateral carotid stenosis and their relationship with symptomatology. Using transcranial Doppler ultrasound, cerebrovascular reactivity to hypercapnia in middle cerebral arteries was evaluated with the breath-holding index (BHI) in 42 patients with internal carotid occlusion and severe contralateral carotid stenosis and in 40 control subjects. A significant decrease of BHI on the occluded side was observed in symptomatic patients with respect to asymptomatic ones (0.12+/-0.1 vs. 0.75+/-0.4, P<0.0001) and with respect to the control group (1.11+/-0.1, P<0.0001). The difference was also significant between asymptomatic patients and controls (P<0.0001). Breath-holding values on the stenotic side were significantly higher (P<0.0001) in asymptomatic patients (1.01+/-0.2) with respect to symptomatic ones (0.39+/-0.1). A significant difference (P<0.0001) was also present between controls and symptomatic patients. The pattern of cerebrovascular reactivity in patients with severe bilateral carotid steno-occlusive disease seems to be strictly dependent on the presence of previous symptoms. Further studies are needed to investigate whether the study of cerebral hemodynamics in patients with bilateral carotid artery disease is important for planning therapeutic strategies.

Aged↗

PubMed1999

Impaired apoptosis in mitogen-stimulated lymphocytes of patients with multiple sclerosis.

We investigated the sensitivity to cell death of peripheral blood mononuclear cells (PBMCs) from patients with multiple sclerosis (MS). PBMCs from MS patients, following PHA stimulation, were less sensitive to cell death than those from healthy donors (mean +/- s.e.m., 22.5 +/- 1.9 in MS patients vs 36.5 +/- 2.8 in healthy controls; p = 0.0003). However, when Fas-agonist antibody was added, the increase in respect to apoptosis induced by mitogen alone was even higher in MS patients than in controls. In addition, PHA-activated PBMCs from MS patients showed higher surface expression of Fas than controls, while Bcl-2 expression was decreased. This finding raised the question of whether an impaired generation of apoptotic signals may be contributing to the immune component of MS.

Adult↗

PubMed1999

Emotion-related cerebral asymmetry: hemodynamics measured by functional ultrasound.

This study assessed the use of transcranial Doppler ultrasound in detecting selective changes in cerebral blood flow velocity during emotional processes. The role of the respective hemispheres in emotional processing is controversial. Cerebral control of emotional processing has previously been investigated by analysis of patients with unilateral brain damage, experiments with selective stimulation of only one hemisphere, and more recently by imaging techniques measuring local cerebral blood flow. We investigated mean flow velocity continuously and simultaneously in both the right and left middle cerebral arteries (MCAs) in 16 healthy right-handed young subjects at rest and during the performance of three tasks: task 1: 15 slides with nonemotional content; task 2: 15 slides with negative emotional content; task 3: 15 slides with nonemotional content with different content from that in task 1. The three tasks produced significantly different effects on the right and left hemispheres. During the two nonemotional tasks the increase in mean flow velocity over basal values was similar in the two MCAs (task 1: left MCA = 3.27 +/- 1.9%; right MCA = 3.63 +/- 2.1%; task 3: left MCA = 2.42 +/- 0.7%; right MCA = 2.56 +/- 1.3%); the negative emotional task was accompanied by a significantly higher increase in the right (11.31 +/- 1.6%) than in the left MCA (4.72 +/- 3.7%; analysis of variance two-way interaction: side of recording x task, F = 43.6, P < 0.001). These results show the possibility of obtaining specific functional information from bilateral transcranial Doppler ultrasound and suggest the involvement of the right hemisphere in emotional processing.

Adult↗

PubMed1999

Lexical and conceptual components of stem completion priming in patients with Alzheimer's disease.

This study evaluated the hypothesis of dissociation between normal lexical but deficient conceptual repetition priming in patients with Alzheimer's disease (AD). For this purpose, we administered to patients with AD and age-matched normal controls the Stem Completion task. In Experiment 1, the level of word processing during study was manipulated by requiring subjects to count vowels (graphemic condition) or generate meanings (semantic condition) of target words. In Experiment 2, the presentation modality was varied during the study to obtain an intramodal and crossmodal repetition priming. Probably due to a floor effect of performance in the graphemic condition, in Experiment 1, AD patients exhibited lower priming than normal controls for the semantically processed words but comparable priming for the graphemically processed ones. In contrast, in Experiment 2, AD patients were poorly primed both in the intra- and crossmodal conditions. Results question the hypothesis of a lexical/conceptual dissociation in the repetition priming exhibited by AD patients and call for other explicative hypotheses of the dissociation between normal and deficient forms of repetition priming in degenerative dementia.

Aged↗

PubMed1999

Interhemispheric asymmetries in the perception of unimanual and bimanual cutaneous stimuli. A study using transcranial magnetic stimulation.

Previous studies have shown that transcranial magnetic stimulation (TMS) of the sensorimotor cortex can induce a suppression of cutaneous perception from the fingers of the contralateral hand. In this work, 17 normal subjects were submitted to focal TMS of frontal and parietal scalp sites of each hemisphere. TMS was delivered at two interstimulus intervals (20 and 40 ms) following a cutaneous electrical stimulation of the first, third and fifth digits of either hand or both hands near the subjective threshold of perception. The aim of our study was to investigate whether TMS could detect an asymmetrical hemispheric specialization in the sensory perception of unimanual and bimanual, ipsilateral and contralateral sensory stimuli. At each interpulse interval, the right parietal cortex was significantly more sensitive to TMS interference with stimulus detection for both contralateral and ipsilateral stimuli compared with the left parietal cortex. These effects were mainly evident during bimanual discrimination tasks. Our results are indicative of an interhemispheric difference in the detection of cutaneous sensation, showing right hemispheric prevalence in the perception of contralateral as well as of ipsilateral stimuli. They provide neurophysiological support in normal humans to the clinical evidence which indicates that right hemisphere lesions can indeed produce deficits in the perception of ipsilateral sensory stimuli.

Adult↗

PubMed1999

Left frontal transcranial magnetic stimulation reduces contralesional extinction in patients with unilateral right brain damage.

It has been demonstrated previously that transcranial magnetic stimulation (TMS) of the sensorimotor cortex can induce transient suppression of the perception of cutaneous near-threshold stimuli from fingers of the contralateral hand in normal individuals. One explanation accounting for deficits in the exploration of contralateral space following a unilateral hemispheric lesion refers to a loss of the normal interhemispheric balance, with a resultant hyperactivation of the unaffected hemisphere due to the release of reciprocal inhibition by the affected one. In order to verify this hypothesis, we investigated the effects of a TMS-induced transient dysfunction of the normal hemisphere upon contralateral tactile extinctions in two groups: (i) 14 right brain-damaged patients and (ii) 14 left brain-damaged control patients. Single-pulse TMS was delivered to frontal and parietal scalp sites of the unaffected hemisphere after an interval of 40 ms from an electrical unimanual or bimanual digit stimulation. In right brain-damaged patients, left frontal TMS significantly reduced the rate of contralateral extinctions compared with controls. After left parietal TMS, the number of extinctions was comparable to the baseline. This pattern of increased sensitivity to cutaneous stimulation ipsilateral to TMS was not observed in left brain-damaged control patients. In this group, right hemisphere TMS did not significantly alter the recognition of bimanual stimuli delivered to the space contralateral to the lesion. The suggestion is made that extinctions produced by right brain damage may be dependent on a breakdown in the balance of hemispheric rivalry in directing spatial attention to contralateral hemispace, so that the unaffected hemisphere generates an unopposed orienting response to the side of the lesion. The mechanisms whereby the left frontal TMS transiently ameliorates these deficits may involve stimulus-induced removal of a left frontal-right parietal transcallosal inhibitory flow, although interactions at subcortical levels cannot be excluded.

Aged↗

PubMed1999

Cerebrovascular reactivity in carotid artery occlusion: possible implications for surgical management of selected groups of patients.

OBJECTIVES: The aim of this study was to use transcranial Doppler ultrasonography to investigate cerebrovascular reactivity to hypercapnia in the middle cerebral arteries of patients with carotid occlusion with different outcomes. PATIENTS AND METHODS: Cerebrovascular reactivity to hypercapnia was calculated with the breath-holding index (BHI). Patients with unilateral carotid occlusion were divided as follows: asymptomatic (20 patients), transient ischemic attack (TIA) (20 patients), minor (20 patients) and major stroke (14 patients). Values of BHI homolateral to the carotid occlusion were compared with those of 25 healthy subjects and 34 stroke patients without significant carotid stenosis. RESULTS: BHI values were comparable in healthy controls, non stenotic stroke patients and asymptomatic occluded patients. BHI values of patients with symptomatic occlusion were significantly lower than those of the above-mentioned groups (P<0.0001). Moreover, the reduction of BHI was significantly associated with the extent of the neurological impairment. In fact, BHI values were significantly higher in TIA than in minor and major stroke (P<0.0001) and in minor than in major stroke patients (P<0.02). Finally, we found that a BHI value homolateral to carotid occlusion of 0.69 can be considered the cut-point for distinguishing between symptomatic and asymptomatic patients. CONCLUSION: Prospective studies are needed to demonstrate if the presence of this threshold value may help in selecting a subset of patients with asymptomatic carotid occlusion or with transient or mild neurological deficit with the highest probability of benefiting from surgical therapy.

Analysis of Variance↗

PubMed1999

Verbal working memory deficit in Parkinson's disease subjects.

The aim of the present work was to evaluate verbal working memory in patients affected by Parkinson's disease (PD). In particular, tests that explore the functionality of the Articulatory Loop and of the Central Executive during verbal tasks were given. PD patients displayed normal phonological similarity, word length and word frequency effects in a Word span task, thus demonstrating adequate retention capacity of the phonological store, normal functioning of the articulatory rehearsal mechanism and a normal contribution of lexical-semantic knowledge to verbal immediate recall. In the Brown-Peterson task, PD patients showed abnormal performance decay on the letter recall task when articulatory rehearsal was inhibited by a serial subtraction concurrent task. These data provide evidence for normal functioning of the Articulatory Loop in PD patients. However, when the verbal recall task is more attention demanding, PD patients show deficient performance levels, presumably due to depleted processing resources by the Central Executive.

Adult↗

PubMed1998

Cerebral hemodynamics in young hypertensive subjects and effects of atenolol treatment.

The aim of this study was to evaluate changes in cerebral hemodynamics in young patients with uncomplicated hypertension before and after effective antihypertensive treatment with a beta-blocker drug. Changes in mean flow velocity in the middle cerebral artery from normal condition to hypercapnia were evaluated by means of a transcranial Doppler in 42 hypertensive patients and 21 healthy subjects comparable for age and sex distribution. We obtained hypercapnia with breath-holding and evaluated cerebrovascular reactivity with the breath-holding index (BHI). After a baseline evaluation (time 0), patients were randomly assigned to a placebo (group 1) or atenolol (group 2) therapy. The evaluation was repeated after 30 (time 1) and 60 (time 2) days of treatment. Before treatment, hypertensive patients had significantly lower BHI values (0.96 +/- 0.1 group 1 and 0.85 +/- 0.3 group 2) than controls (1.69 +/- 0.4) (P < 0.0001). During treatment, mean blood pressure significantly decreased in group 2 patients. In the same group, BHI values significantly increased with respect to the pre-treatment evaluation: 1.39 +/- 0.2 at time 1 and 1.44 +/- 0.2 at time 2 (P < 0.0001). On the contrary, mean blood pressure and BHI values remained unchanged in the placebo group. Furthermore, BHI values were significantly higher in group 2 than in group 1 patients at times 1 (P < 0.001) and 2 (P < 0.0001). These findings suggest that hypertension causes reduced capability of cerebral vessels to adapt to functional changes. This condition, which is reversible after treatment, could be implicated in the increased susceptibility to ischemic stroke in hypertension.

Adult↗

PubMed1998

Hand motor cortical area reorganization in stroke: a study with fMRI, MEG and TCS maps.

The anatomical and functional correlates of the hand sensorimotor areas was investigated in a stroke patient with a malacic lesion in the left fronto-parieto-temporal cortex. The patient presented hemiplegia and motor aphasia 12 months earlier, followed by an excellent motor recovery. Transcranial magnetic stimulation mapping, functional magnetic resonance and magnetoencephalography were used as methods of functional imaging and all yielded consistent results. In particular, an asymmetrical enlargement and posterior shift of the sensorimotor areas localized in the affected hemisphere were found with all three techniques. Aspects related to brain 'plasticity' for functional recovery are discussed.

Cerebrovascular Disorders↗

PubMed1998

Post-stroke rehabilitation: an economic or medical priority? Current issues and prospects in light of new legislative regulations.

The aim of this study was to evaluate: 1) whether the reduction in duration of in-patient rehabilitation imposed by the Italian Ministry of Health's circular of 29/6/95 has been accompanied by a decline in the results achieved; and 2) whether the system of basing payments on diagnosis related group (DRG) criteria is capable of correctly evaluating differences in post-stroke clinical pictures. The study involved 461 of 497 patients consecutively admitted between 1991 and 1996 for rehabilitation after a first stroke. The average duration of hospitalisation for the period 1995-1996 was significantly shorter (p<0.001) than that of the previous years; at the same time, there was a significant increase (p<0.05) in the number of poor responders in both neurological and functional (mobility) terms. Furthermore, the early discharge after 60 days of the 1995-1996 patients compromised the stabilisation of recovery and led to a subsequent functional decline. It is therefore hoped that the current regulations will be revised and that payments based on a functional related group (FRG) criterion will be introduced.

Aged↗

PubMed1998

Associative visual agnosia resulting from a disconnection between intact visual memory and semantic systems.

We report the case of a patient (RC) who developed a severe visual agnosia, associated to alexia without agraphia, color anomia and amnesia, following an ischemic stroke in the territory supplied by the left posterior cerebral artery. Based on his proficient performance on tests evaluating analysis of elementary visual features, formation of viewer-centered and object-centered representations of visual stimuli and discrimination between drawings representing real and unreal objects, we concluded that the critical locus of deficit was a disconnection between the normally functioning visual memory store and the semantic system. RC's disturbance in visual processing of human faces paralleled his recognition disorder of other classes of objects. The possible contribution of neurobiological factors in determining RC's agnosic deficit is discussed.

Aged↗

PubMed1998

Retrograde memory deficits in severe closed-head injury patients.

A battery of tests evaluating different aspects of retrograde memory (autobiographical, public events, semantic knowledge) was administered to a group of 20 patients who had suffered from a severe closed-head injury (CHI) and who had recovered from the post-traumatic amnesia period and to a group of sex-, age- and education-matched normal controls. Results document a high prevalence of retrograde memory deficits among CHI individuals. The deficit involves both autobiographical and public events memories and extends to early acquired basic and cultural knowledge. The severity of the deficit does not vary according to some kind of temporal gradient or according to a presumed hierarchical or modality organization of the semantic system. However, in the domain of basic knowledge it more severely affects information pertaining to living than nonliving categories of objects. With the exception of a more severe deficit in retrieving autobiographical events occurred in the last year before trauma in a subgroup of patients with focal lesions restricted to the right hemisphere as compared to left lesioned patients, no clear relationship emerges between severity of the retrograde memory deficit and locus of focal cerebral lesions as demonstrated by neuroradiological exams.

Adolescent↗

PubMed1998

Analysis of the memory impairment in a post-encephalitic patient with focal retrograde amnesia.

This study aimed to characterize the qualitative pattern of focal retrograde memory impairment shown by a post-encephalitic patient (AV). AV's memory deficit encompassed autobiographical data, public events and famous people. In a public events questionnaire, she demonstrated a smooth negative temporal gradient with good recollection of events that occurred about 15 years before the disease but poor memory of more recent events. Her visual input lexicon was unimpaired, as demonstrated by normal lexicality judgment for words and normal familiarity judgment for proper names, but she was poor in familiarity judgment for famous faces (prosopagnosia) and in accessing the meaning of words or specific information about people. The cerebral MRI demonstrated widespread abnormal intensity areas encroaching upon the white matter of temporal, parietal and occipital lobes but sparing temporal poles and orbito-frontal cortex.

Adult↗

PubMed1998

Changes in functional outcome in inpatient stroke rehabilitation resulting from new health policy regulations in Italy.

This study was designed to assess whether enforcement of new health policy regulations in Italy limiting fully paid hospital stay to 60 days has actually caused a decrease in rehabilitation outcomes of stroke patients. Final sample included 370 out of 398 consecutive patients hospitalized between 1993 and 1996 for first stroke sequelae. Rehabilitation results were compared between subgroups of patients admitted before and after new Italian regulations. Length of stay was significantly (p < 0.001) shorter in 1996 than in previous years. However, between 1993 and 1996 a significant (p < 0.05) decrease in effectiveness on mobility and a significant (p < 0.05) increase in "low responders" on both daily living activities and mobility was observed. Moreover, in 1995-96 the precocious discharge of patients compromised stabilization of recovery with subsequent functional worsening. After discharge, outpatient rehabilitation treatment was able to conserve achieved mobility status, but not functional status on daily living activities. We suggest revising the present regulation for medical rehabilitation services to one based on FRGs (functional related groups), so that the appropriate treatment can be carried out for each patient.

Journal Article↗