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C Caltagirone

Publications and source records attributed to C Caltagirone.

At least 55 records · Page 3Linked to original sources
PubMed2001

Remembering what but not where: independence of spatial and visual working memory in the human brain.

We report the neuropsychological and MRI investigation of a patient (MV) who developed a selective impairment of visual-spatial working memory (WM) with preservation not only of verbal, but also of visual shape WM, following an ischemic lesion in the cerebral territory supplied by one of the terminal branches of the right anterior cerebral artery. MV was defective in visual-spatial WM whether the experimental procedure involved arm movement for target pointing or not. Also, in agreement with the role generally assigned to visual-spatial WM in visual imagery, MV was extremely slow in the mental rotation of visually and verbally presented objects. In striking contrast with the WM deficit, MV's visual-spatial long-term memory was intact. The behavioral and neuroanatomical investigation of MV provides support for the hypothesis that the superior frontal gyrus (BA 6) and the dorsomedial cortex of the parietal lobe (BA 7) are part of the neural circuitry underlying visual-spatial WM in humans.

Brain↗
PubMed2001

Urinary N-acetyl-beta-D-glucosaminidase concentration in patients with spinal cord injury: relationship with urodynamic parameters.

OBJECTIVES: To investigate the relationships between urinary N-acetyl-beta-D-glucosaminidase (NAG) concentrations and urodynamic parameters in patients with spinal cord injury (SCI). NAG has been proposed as a marker of renal damage. METHODS: Twenty-three patients with SCI were evaluated with urodynamic studies. Urine samples were collected from the 23 patients and 10 healthy volunteers, the NAG levels were evaluated, and the urodynamic parameters were compared with the urinary NAG levels. The patients were divided into two groups according to the amplitude of the hyperreflexic detrusor contractions (HDCs): group A, patients with an HDC amplitude of 40 cm H(2)O or greater, and group B, patients with an HDC amplitude of less than 40 cm H(2)O; group C was composed of healthy volunteers. The urinary NAG concentrations in the three groups were compared. RESULTS: A positive correlation was found between the urinary NAG levels and the HDC amplitude and detrusor leak point pressure (P = 0.015 and 0.007, respectively). The urinary NAG concentration was 3.38 U/g in group A, 2.14 U/g in group B, and 2.12 U/g in group C. The differences in the urinary NAG concentrations between groups A and B and between groups A and C were statistically significant (P = 0.03 and P <0.001, respectively). The concentrations between groups B and C were comparable. CONCLUSIONS: In our experience, the only urodynamic parameters that clearly and positively correlated with the urinary NAG levels were those expressing the amplitude of intravesical pressure. This result stresses the importance of reducing the intravesical pressure in patients with SCI using alternative treatments or surgical procedures if the usual conservative therapies are not effective.

Acetylglucosaminidase↗
PubMed2001

Neuropsychological assessment of patients with severe neuromotor and verbal disabilities.

In people with cerebral palsy, severe neuromotor disability and communication problems make standard neuropsychological tests impossible. Therefore, alternative methods and specific aids must be developed to allow patients to autonomously respond to the examiner's questions. In the present individuals and study, a neuropsychological evaluation was made of a group of eight individuals with cerebral palsy, and severe neuromotor and verbal disabilities, and a group of 19 normal subjects matched for mental age. The tests were administered using an autonomous selection method in which the patient selects the various responses through specific aids without the examiner's interference. Patients' group performances in visuo-spatial and memory tests were on average lower than the mean of the control group. In the verbal domain, patients' scores were comparable to those of normal children in all tests but one assessing the comprehension of syntactically complex sentences. An analysis of the patients' individual performances also revealed heterogeneous cognitive profiles: some patients presented a homogeneously distributed cognitive impairment and others a more selective one. This finding is particularly important for planning differentiated learning programmes, and identifying suitable communicative instruments in rehabilitative and educational settings.

Adolescent↗
PubMed2001

Intact cross-modality text-specific repetition priming in patients with Alzheimer's disease.

This study was aimed at investigating the basic mechanisms of the normal repetition priming evoked by text re-reading procedures in Alzheimer's disease (AD) patients (Monti, Gabrieli, Wilson, & Reminger, 1994; Monti et al., 1997). For this purpose, we contrasted the reading facilitation elicited by previous reading or listening to a text in a sample of AD patients and a group of age-matched normal controls. Consistent with previous evidence in normal undergraduates (Levy & Kirsner, 1989), previous listening to a text decreased the successive reading time of the same text (cross-modality priming). However, the reading facilitation elicited by previous reading of the same text (within-modality priming) was significantly larger than the facilitation evoked by previous listening. Compared to normal controls, AD patients showed intact cross-modality and within-modality priming. These data are discussed in the light of alternative hypotheses regarding the basic mechanisms of impaired and spared repetition priming in degenerative demented patients.

Aged↗
PubMed2001

Parieto-frontal interactions in visual-object and visual-spatial working memory: evidence from transcranial magnetic stimulation.

This study aimed to investigate whether transcranial magnetic stimulation (TMS) can induce selective working memory (WM) deficits of visual-object versus visual-spatial information in normal humans. Thirty-five healthy subjects performed two computerized visual n-back tasks, in which they were required to memorize spatial locations or abstract patterns. In a first series of experiments, unilateral or bilateral TMS was delivered on posterior parietal and middle temporal regions of both hemispheres after various delays during the WM task. Bilateral temporal TMS increased reaction times (RTs) in the visual-object, whereas bilateral parietal TMS selectively increased RTs in the visual-spatial WM task. These effects were evident at a delay of 300 ms. Response accuracy was not affected by bilateral or unilateral TMS of either cortical region. In a second group of experiments, bilateral TMS was applied over the superior frontal gyrus (SFG) or the dorsolateral prefrontal cortex (DLPFC). TMS of the SFG selectively increased RTs in the visual-spatial WM task, whereas TMS of the DLPFC interfered with both WM tasks, in terms of both accuracy and RTs. These effects were evident when TMS was applied after a delay of 600 ms, but not one of 300 ms. These findings confirm the segregation of WM buffers for object and spatial information in the posterior cortical regions. In the frontal cortex, the DLPFC appears to be necessary for WM computations regardless of the stimulus material.

Adult↗
PubMed2001

Selective sparing of face learning in a global amnesic patient.

OBJECTIVE: To test the hypothesis that visual memory for faces can be dissociated from visual memory for topographical material. METHOD: A patient who developed a global amnesic syndrome after acute carbon monoxide poisoning is described. A neuroradiological examination documented severe bilateral atrophy of the hippocampi. RESULTS: Despite a severe anterograde memory disorder involving verbal information, abstract figures, concrete objects, topographical scenes, and spatial information, the patient was still able to learn previously unknown human faces at a normal (and, in some cases, at a higher) rate. CONCLUSIONS: Together with previous neuropsychological evidence documenting selective sparing of topographical learning in otherwise amnesic patients, this case is indicative of the fact that the neural circuits involved in face recognition are distinct from those involved in the recognition of other visuoperceptual material (for example, topographical scenes).

Acute Disease↗
PubMed2001

Patterns of cognitive impairment in secondary progressive stable phase of multiple sclerosis: correlations with MRI findings.

Cognitive impairment is commonly described in multiple sclerosis (MS), but conflicting results have been reported about its pattern by previous studies focused on heterogeneous patient groups. The aim of this study was to investigate the cognitive skills of a homogeneous group of secondary progressive MS patients, and to examine the relationship of this impairment to MRI parameters. Forty-four MS patients underwent a series of neuropsychological tests devised to explore the main cognitive domains, and T1- and T2-weighted brain MRI. Results showed the presence of deficits of attention, memory, planning abilities, problem-solving and conceptual reasoning (frontal functions) in a subgroup of MS patients. Correlations between the performance in some 'frontal' tests and the extent of frontal lobe MRI lesional area were present, but rather unspecific, the same performance being also correlated with the nonfrontal lesional area. These findings suggest that in MS, overall macroscopic and microscopic brain damage is more important than the corresponding focal brain disease, even in determining deficits of selective cognitive domains.

Adult↗
PubMed2001

Effect of collateral blood flow and cerebral vasomotor reactivity on the outcome of carotid artery occlusion.

BACKGROUND AND PURPOSE: Evidence suggests that an alteration in cerebral hemodynamics plays a relevant role in the occurrence of stroke in patients with carotid occlusion. The purpose of the present study was to evaluate the relationships among baseline characteristics, type and number of collateral pathways, cerebral vasomotor reactivity (VMR), and outcome of patients with carotid occlusion. METHODS: One hundred four patients with symptomatic or asymptomatic internal carotid artery occlusion were followed up prospectively for a median period of 24 months. Cerebral VMR to apnea was calculated with transcranial Doppler ultrasonography by means of the breath-holding index (BHI) in the middle cerebral arteries. The patency of the 3 major intracranial collateral vessels was also evaluated. RESULTS: During the follow-up period, 18 patients experienced an ischemic stroke ipsilateral to internal carotid artery occlusion. Among factors considered, only older age, number of collateral pathways, and BHI values in the middle cerebral artery ipsilateral to the occluded side were significantly associated with the risk of ipsilateral stroke (P<0.001, P=0.008, and P<0.001, respectively; multiple Cox regression analysis). A normal VMR and favorable prognosis characterized patients with full collateral development; in this group, no patient experienced an ischemic event. On the other hand, an impaired VMR and increased probability of experiencing a stroke were found in patients without collateral pathways; the annual risk of ipsilateral stroke in this group was 32.7%. Patients with 1 or 2 collateral pathways showed a different VMR ranging from normal to strongly reduced BHI values. The ipsilateral stroke event risk was 17.5% in patients with 1 collateral vessel and 2.7% in patients with 2 collateral pathways. In this case, the risk of cerebrovascular events occurring during the follow-up period was significantly related to VMR. CONCLUSIONS: These data suggest that cerebral hemodynamic status in patients with carotid occlusive disease is influenced by both individual anatomic and functional characteristics. The planning of strategies to define the risk profile and any attempt to influence patients' outcome should be based on the evaluation of the intracranial hemodynamic adaptive status, with particular attention to the number of collateral vessels and the related VMR.

Aged↗
PubMed2001

Fatigue in progressive multiple sclerosis: results of a randomized, double-blind, placebo-controlled, crossover trial of oral 4-aminopyridine.

Previous studies suggest that aminopyridine may play a role in the symptomatic treatment of fatigue in multiple sclerosis. Although the mechanism underlying the beneficial effect on fatigue remains unclear, it has been proposed that aminopyridines may help to improve conduction in demyelinated central pathways, implicating both axonal and synaptic mechanisms. The objective of the present study is to determine whether 4-AP decreases daily-living fatigue in progressive multiple sclerosis. The effect of 4-AP on other neurophysiological and neuropsychological parameters was also considered. A 'double-blind', randomized, 'placebo-controlled', crossover trial was conducted on 54 patients with progressive multiple sclerosis. All patients received treatment with placebo and 32 mg per day of 4-AP, each for 6 months. The main outcome measure was the Fatigue Severity Scale. Secondary measures were EDSS, cognitive functions and neurophysiological parameters. Forty-nine patients (91%) completed the study. Changes in fatigue scores, EDSS and cognitive functions were not significantly different between 4-AP and placebo. However, when patients treated with 4-AP were divided into two groups according to the serum level of 4-AP, a significant effect on fatigue compared with placebo was observed in the 'high level' (>30 ng/ml) group (P=0.05). Synchronization of motor evoked potentials improved during 4-AP with respect to placebo (P=0.019) and this correlated positively with fatigue reduction (P=0.010). No relevant side effects were observed.

4-Aminopyridine↗
PubMed2001

Cerebral hemodynamics in patients with carotid artery occlusion and contralateral moderate or severe internal carotid artery stenosis.

OBJECT: The purpose of this study was to evaluate cerebral hemodynamics in patients suffering from occlusion of the carotid artery (CA) and contralateral CA stenosis. METHODS: Using transcranial Doppler ultrasonography, the cerebrovascular reactivity to hypercapnia in the middle cerebral arteries was evaluated by calculating the breath-holding index (BHI) of 69 symptomatic patients suffering from internal CA (ICA) occlusion and moderate or severe contralateral ICA stenosis. To evaluate which variables influenced BHIs ipsilateral to the site of ICA occlusion, a multiple stepwise linear regression analysis was performed that included the following factors: patient age, percentage of contralateral ICA stenosis, contralateral BHI, number of collateral pathways, and presence of hypertension, diabetes, smoking, and hyperlipidemia. An analysis of variance was conducted to evaluate the impact of the type of collateral vessels on the BHI. A regression analysis showed that the BHI ipsilateral to the site of ICA occlusion could be accounted for by the contralateral BHI (which was entered at the first step of the analysis, p < 0.001) and by the number of collateral pathways (which was entered at the second step, p = 0.033). Neither the degree of contralateral ICA stenosis nor the other variables could be added to improve the model. The analysis demonstrated that the absence of collateral pathways and the presence of the anterior communicating artery (ACoA) alone were associated with lower BHI values than those found in the presence of two or three collateral vessels, regardless of the presence of an anterior collateral pathway. CONCLUSIONS: On the basis of these data one can infer that the cerebral hemodynamic status of patients with occlusive disease of the CA is influenced by individual anatomical and functional characteristics. Because improvement in contralateral hemodynamics after surgical correction of an ICA stenosis can only be expected in the presence of an ACoA, the planning of strategies for influencing cerebral blood flow distal to an ICA occlusion and, in particular, the consideration of a contralateral carotid endarterectomy, should be preceded by a careful evaluation of the intracranial hemodynamic adaptive status of the patient. Particular attention should be paid to cerebrovascular reactivity and the number and type of collateral vessels that are present.

Aged↗
PubMed2000

Paired transcranial magnetic stimulation protocols reveal a pattern of inhibition and facilitation in the human parietal cortex.

Intracortical inhibition (ICI) and facilitation (ICF) of the human motor cortex can be induced by paired transcranial magnetic stimulation (TMS). Although demonstrated in experimental animals, the existence of intracortical inhibitory and excitatory circuits in parietal sensory cortex has not been documented in humans. The aim of this study was to investigate the effects of paired TMS of the parietal cortex on contralateral tactile perception. Fifteen healthy subjects were involved in a task of discrimination of electrical stimuli delivered at near-threshold intensity of sensory perception over the left thumb. Paired TMS was delivered with a focal coil on the right posterior parietal lobe after various delays from the presentation of finger stimuli. The effects of different interstimulus intervals (ISI: 1, 3, 5, 7, 10 and 15 1 1 Bms1B) between the conditioning and the test TMS stimulus on tactile perception were studied. The conditioning stimulus intensity was set at 70 % of motor threshold, while test TMS intensity was 130 % of motor threshold. Single pulse suprathreshold TMS interfered with the perception of finger stimuli, while subthreshold stimuli such as the 'conditioning' stimuli had no effect on sensory perception. Paired TMS differentially influenced the performance depending on the ISI. At an ISI of 1 1 1 Bms1B, paired TMS stimuli induced a significant worsening of the performance compared with single pulse TMS; at an ISI of 5 1 1 Bms1B, paired TMS stimuli induced a significant facilitation of the performance compared with single pulse TMS, restoring baseline performance levels. These results suggest that paired TMS can reveal a selective pattern of ICI and ICF in the human parietal cortex.

Adult↗
PubMed2000

Correlation of cerebral hemodynamic changes during mental activity and recovery after stroke.

OBJECTIVE: To investigate the correlation between changes in cerebral functional activity during mental engagement and the potential for neurologic recovery after stroke. BACKGROUND: Transcranial Doppler ultrasonography (TCD) makes it possible to detect the dynamic adjustment of cerebral perfusion related to functional neuronal changes. METHODS: TCD monitoring of flow velocity changes in the middle cerebral artery of 29 ischemic stroke patients was performed during an object recognition task. The study took place within 4 weeks from stroke onset. Based on recovery occurring after 2 months, the patients were divided into four groups depending on the side of hemispheric lesion and the presence or absence of neurologic recovery. Ten healthy subjects served as control subjects. RESULTS: During the recognition task, control subjects showed a bilateral increase in flow velocity with respect to the rest phase (right side, 7.02 +/- 1.3%; left side, 6.65 +/- 1. 1%), with no side-to-side difference. In patients who experienced recovery, a similar pattern of bilateral activation was observed, irrespective of the side of the lesion. Conversely, in patients with no recovery, the increase of flow velocity was significantly higher on the side contralateral to the brain lesion (p < 0.0001) with respect to the lesion side. Performance during the recognition task was comparable in the four groups of patients. CONCLUSIONS: These findings suggest that satisfactory recovery from a neurologic deficit requires the persistence of functional activity in the damaged hemisphere despite the presence of an anatomic lesion. The possibility of obtaining early prognostic indications with TCD may be relevant for an early selection of patients with the best probability of benefiting from rehabilitation therapy.

Aged↗
PubMed2000

Impaired cerebral vasoreactivity and risk of stroke in patients with asymptomatic carotid artery stenosis.

CONTEXT: Standards for treating patients with asymptomatic carotid artery stenosis have been difficult to establish because of the lack of evidence for factors influencing these patients' prognoses. However, preliminary evidence suggests that an alteration in cerebral hemodynamic function may play a relevant role in the occurrence of stroke in patients with carotid artery disease. OBJECTIVE: To investigate the relationship between cerebrovascular reactivity to hypercapnia and cerebrovascular events in patients with severe unilateral asymptomatic carotid artery stenosis. DESIGN AND SETTING: Prospective, blinded longitudinal study conducted in an outpatient neurovascular department in Italy between June 1996 and April 1998, with a median follow-up of 28.5 months. PATIENTS: Ninety-four patients with asymptomatic carotid artery stenosis of at least 70% (74 men; mean age, 71 years). MAIN OUTCOME MEASURES: Subsequent occurrence of cerebral ischemic events (transient ischemic attack or stroke) or death, analyzed by cerebrovascular reactivity to hypercapnia (measured by transcranial Doppler ultrasonography and calculated by the breath-holding index values in the middle cerebral arteries). RESULTS: The overall annual rate for all ischemic events was 7.9%. Seventeen patients (18%) had ischemic events, all but 1 of which were ipsilateral to the carotid artery stenosis. Among factors considered, only lower breath-holding index values in the middle cerebral artery ipsilateral to carotid artery stenosis were significantly associated with the risk of an event (hazard ratio, 0.09; 95% confidence interval, 0.02-0.38; P=.001, by multivariate analysis). Based on data from previously studied healthy subjects, the cutoff of the breath-holding index for distinguishing between impaired and normal cerebrovascular reactivity was determined to be 0.69. Using this cutoff, the annual ipsilateral ischemic event risk was 4.1% in patients with normal and 13.9% in those with impaired breath-holding index values. CONCLUSIONS: These results suggest a link between impaired cerebrovascular reactivity and the risk of ischemic events ipsilateral to severe asymptomatic carotid stenosis.

Aged↗
PubMed2000

Developmental dissociation between visual and auditory repetition priming: the role of input lexicons.

Contrasting theories posit the source of verbal repetition priming in the activation of preexisting memory representations in the input lexicons or, alternatively, in the formation of new episodic memory traces. The two hypotheses predict different outcomes from the comparison of developmental rates of visual and auditory verbal repetition priming. The activation theory predicts a developmental dissociation between the early maturation of auditory priming and the later maturation of visuo-verbal priming, contingent upon the discrepant acquisition rates of the auditory and visual input lexicons. The episodic theory, instead, does not make such an assumption. We administered visual and auditory implicit Stem Completion to 40 reading beginners (first-graders), 40 third-graders and 20 fifth-graders. Consistent with previous reports, auditory priming was stable across different age groups. Visual priming and a measure of lexicality in reading, instead, showed a parallel developmental increase passing from reading beginners to third-graders and to fifth-graders. In the overall group, visual priming and the measure of lexicality in reading were significantly associated. These data describe a new developmental dissociation in the memory abilities of normal children and provide further support for the hypothesis that repetition priming for words reflects facilitated access to previously established memory representations.

Auditory Perception↗
PubMed2000

Deficient intentional access to semantic knowledge in patients with severe closed-head injury.

Patients after severe closed-head injury (CHI) demonstrate reduced ability to spontaneously utilize semantic memory during word-list memory tests and when requested to answer questions regarding general knowledge. However, they show normal lexical facilitation in both automatic and intentional semantic priming paradigms. The present study was aimed at investigating two alternative hypotheses a) that the deficit in semantic processing after CHI is the result of impaired access to an otherwise normal semantic system or b) that it reflects a loss of knowledge from a deteriorated semantic store. For this purpose, the performance of 15 CHI patients on an automatic Semantic Priming paradigm and on tests of Picture Naming and Semantic Judgment were compared to those of 14 normal controls (NC). Although CHI patients' reaction times were significantly slower than those of NCs, the semantic priming effect was comparable in the two groups. Instead, CHI patients performed significantly worse than NCs in the naming and semantic judgment tasks. These results provide evidence that CHI patients access semantic memory automatically at a normal rate. However, when the task is more demanding in terms of processing requests, then CHI patients' performance becomes defective.

Adult↗
PubMed2000

Neurophysiological evaluation of tactile space perception deficits through transcranial magnetic stimulation.

We describe a procedure useful to investigate the contralateral space perception deficits frequently encountered in patients with unilateral right brain damage. In particular, we focused on the phenomenon of extinction, i.e., the failure to perceive a contralesional stimulus only when a symmetrical contralateral stimulus is simultaneously applied. Fifteen right brain- and 15 left brain-damaged patients were examined. Somatosensory perception was evaluated by using a dedicated electronic device able to provide electrical stimuli of variable intensity to digits of one or both hands. The electrical stimulator was able to trigger a magnetic brain stimulator connected with a focal figure of eight coil. Threshold electrical stimuli were delivered to one or both hands of the patients, who were asked to indicate whether they perceived the stimulus (i) and to localise it (them). The electrical stimulator was connected with a magnetic stimulator with an interstimulus interval (ISI) of 40 msec (electrical stimulation preceding the transcranial one). Focal threshold transcranial magnetic stimulation (TMS) was applied to frontal and parietal scalp sites of the unaffected hemisphere. At each interpulse interval we found that TMS of the unaffected hemisphere was associated to a decrease in the level of contralesional extinction. Our method demonstrates that a basic deficit underlying neglect and extinction of contralateral space in unilaterally brain damaged patients is the interhemispheric imbalance between the two hemispheres in directing contralateral attention. A transient interference with the function of the unaffected hemisphere can improve these deficits, suggesting a possible application of TMS in the daily clinical practice for speeding up recovery from neglect.

Cognition↗