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Biomedical subjects

B Pillon

Publications and source records attributed to B Pillon.

At least 55 records · Page 3Linked to original sources
PubMed1996

Memory for spatial location is affected in Parkinson's disease.

Are the striato-frontal neuronal circuits implicated in learning of item-specific spatial coordinates? To answer this question, we compared the performance of 20 patients with Parkinson's disease to that of 14 controls matched for age, global cognitive efficiency and mood, on a visuo-spatial learning task with little involvement of motor and constructive functions, allowing control of encoding and comparison of free recall, cued recall and recognition. Compared to controls, patients showed a severe memory impairment for visuo-spatial location of pictures, contrasting with relative preservation of verbal memory, and mild difficulties in perceptive visuo-spatial and executive functions. These results implicate striato-frontal neuronal circuits in memory for spatial location.

Aged↗
PubMed1996

Delayed response tasks in basal ganglia lesions in man: further evidence for a striato-frontal cooperation in behavioural adaptation.

To determine the respective contribution of the subcortical structures and the prefrontal cortex in behavioural adaptation, we applied the delayed response paradigm, considered as a functional marker of the dorsolateral region of the prefrontal cortex, to patients with striatal dysfunction: Parkinson's disease (n = 27), progressive supranuclear palsy (n = 20); to patients with prefrontal lesions (n = 10) and to normal control subjects (n = 24). The performance of each group was compared in four experiments: a delayed response task in which the correct answer was previously indicated by an explicit cue (externally guided task); delayed alternation and non-alternation tasks coupled with a delayed reversal task in which the patient had to discover the rule by himself in the absence of explicit cues (internally driven tasks). All groups of patients showed a short-term spatial representational memory deficit in the externally guided situation. Patients with striatal dysfunction showed difficulties in re-engaging attention on a new programme and in maintaining it. However, they did not express the spontaneous tendency to alternate nor the severe difficulties in disengaging from a previous pattern of response demonstrated by patients with prefrontal lesions. These results validate the concept of a striato-frontal functional system in humans and suggest the existence of two different levels of behavioural organization: elaboration of new programmes of behaviour in association with inhibition of previously established ones, that might be under frontal lobe control: maintenance of the new programme until the action has been accomplished and automatization for a routine utilization, that might be under control of the striatum.

Adaptation, Psychological↗
PubMed1996

Encoding of sequence and boundaries of scripts following prefrontal lesions.

Script analysis was investigated in patients with lesions in the prefrontal (n = 10) and posterior (n = 8) cortical regions, and in normal subjects (n = 15). The selection and temporal organization of relevant actions belonging to different pre-established sequences were studied in three different situations: (A) script with headers, (B) script with headers and distractors, and (C) scripts without headers. Contrarily to Normals and Posterior patients, Frontal patients committed sequence and boundary errors, and failed to eliminate distractors elements. The analysis of errors suggests two different cognitive modes of representing actions: (1) One using temporal contiguity between actions, that would be mainly under the control of the posterior associative areas; (2) the other, using the goal of the action and its consequences as a binding element between script and context, that would require the intervention of prefrontal cortex.

Adolescent↗
PubMed1995

Congruent unilateral impairments for real and imagined hand movements.

The chronometry of imagined and actual movements was investigated in a patient with a unilateral lesion of the motor cortex. Motor imagery generated highly accurate estimates of motor performance in a variety of situations, reflecting the hypokinesia of the contralesional hand. There were parallel increases in mental and actual movement times from proximal to distal limb segments. Bimanual movements adopted the slower speed of the impaired hand in both conditions. Imagined motor sequences to the beat of a metronome predicted the maximum speed reached in actual performance. Finally, visually guided pointing showed the same target-size effects in the imagery and movement conditions. The results are in agreement with the hypothesis that common cerebral motor representations are activated when imaging and planning voluntary movements.

Aged↗
PubMed1995

Diagnosis of "sporadic" Huntington's disease.

The diagnosis of Huntington's disease (HD) in patients with progressive chorea and mental impairment, but without similarly affected relatives, remains uncertain and impedes genetic counseling. Twenty patients with suspected HD, but with no family history of the disease underwent molecular analysis of the CAG repeat in the IT15 gene for HD. Eighteen patients displayed the HD expanded allele and two had CAG repeats in the normal range. Neuropsychological tests could be performed in 12 of the 20 patients. Of these 10 with the expanded allele presented the deficits typical of HD, but not the two patients without the HD mutation. This study shows that a neuropsychological pattern is specific to patients with the expanded CAG and that most isolated patients with suspected HD are in fact affected.

Adult↗
PubMed1995

A selective impairment of hand posture for object utilization in apraxia.

This study reports the case of an apraxic patient who was impaired in all aspects of gestural behavior following bilateral posterior parietal cortex lesions. The main impairment concerned manual prehension of objects during their utilization. The deficit contrasted with both normal movement trajectories of the arm during execution of such gestures, and with accurate manual prehension in the context of simple reaching movements. Although recognition of gestures and pantomimes made by the examiner was preserved, the patient showed a striking inability to visually discriminate or describe manual prehension associated with object utilization. We thus propose the existence of specialized cortical mechanisms for the representation and activation of the postural schemata of the hand required for complex actions.

Apraxias↗
PubMed1995

Selective impairments in managerial knowledge following pre-frontal cortex damage.

Script generation was investigated in patients with lesions in the prefrontal (n = 9) and posterior (n = 8) cortical regions and in normal subjects (n = 16). Three different activities ranging in degree of familiarity were studied. Frontal patients did not differ from patients with posterior lesion and Normal subjects in the number of actions evoked, mean evocation time, or centrality. Impairments in script information processing were observed only in patients with prefrontal lesions, and for the three types of scripts. Specifically these patients made errors in ordering actions in the correct temporal sequence, failed to close scripts and to remain within the stated boundaries, and made deviant estimates of action importance. The results suggest that pre-frontal cortical lesions provoke a selective impairment in managerial knowledge (Grafman, 1989) that may contribute to difficulties in the formulation and execution of plans.

Adult↗
PubMed1995

Does the enhancement of cholinergic neurotransmission influence brain glucose kinetics and clinical symptomatology in progressive supranuclear palsy?

Cholinergic systems are markedly affected both in cortical and subcortical cerebral areas of patients with progressive supranuclear palsy (PSP). To determine whether it is possible to modify the clinical picture of PSP through the enhancement of brain cholinergic neurotransmission, we studied the effects of physostigmine, an anticholinesterase reference drug, on symptoms and brain glucose metabolism using [18F]fluorodeoxyglucose (FDG) and PET. Patients were evaluated blind in a randomized order with both placebo and physostigmine infusions after an individual determination of maximal tolerated dose. Under steady-state physostigmine infusions, although glucose consumption was not significantly modified, the entry of glucose from blood to brain was regionally increased from 8 to 32% of placebo values suggesting an increase in cerebral blood flow (CBF) or an increase in the activity of brain glucose transporter. Following physostigmine administration in the same patients: the errors in antisaccades during ocular movement testing were significantly reduced, a significant reduction in errors or performance was found in four out of seven neuropsychological tests, and motor disability was not significantly altered. Although the precise pathophysiology of these physostigmine-induced effects needs further investigations, our study suggests that part of the clinical symptomatology in PSP could be relieved by the enhancement of brain cholinergic neurotransmission.

Aged↗
PubMed1995

Neuropsychological pattern of striatonigral degeneration: comparison with Parkinson's disease and progressive supranuclear palsy.

To study the neuropsychological pattern of striatonigral degeneration (SND), 14 consecutive patients with probable SND were submitted to an extensive battery of neuropsychological tests. Compared with controls the performance of patients with SND was impaired on category and phonemic fluency, frontal behaviours, trail making test A and B, and free recall of the Grober and Buschke test, but normal on the revised WAIS verbal scale, Raven 47 coloured progressive matrices, Wechsler memory scale, California verbal learning test, Wisconsin card sorting test, and the Stroop interference condition. The performance of patients with SND was also compared with that of 14 patients with Parkinson's disease and 14 patients with progressive supranuclear palsy (PSP) matched for age at onset, duration of disease, severity of intellectual deterioration, and depression. The results showed that the dysexecutive syndrome of SND is similar to that of Parkinson's disease and less severe than in PSP.

Analysis of Variance↗
PubMed1995

Memory disorders in probable Alzheimer's disease: the role of hippocampal atrophy as shown with MRI.

Magnetic resonance based volumetric measures of hippocampal formation, amygdala (A), caudate nucleus (CN), normalised for total intracranial volume (TIV), were analysed in relation to measures of cognitive deterioration and specific features of memory functions in 18 patients with probable Alzheimer's disease. Neuropsychological examination included the mini mental state examination (MMSE), the Mattis dementia rating scale (DRS), tests of executive functions, assessment of language abilities and praxis, the Wechsler memory scale (WMS), the California verbal learning test (CVLT) and the Grober and Buschke test. The volume of the hippocampal formation (HF/TIV) was correlated with specific memory variables: memory quotient and paired associates of the WMS; intrusions and discriminability at recognition for the Grober and Buschke test. By contrast, except for intrusions, no correlations were found between memory variables and the volume of amygdala (A/TIV). No correlations were found between the volume of caudate nuclei (CN/TIV) and any neuropsychological score. The volume of the hippocampal formation was therefore selectively related to quantitative and qualitative aspects of memory performance in patients with probable Alzheimer's disease.

Aged↗
PubMed1995

The neuropsychological pattern of corticobasal degeneration: comparison with progressive supranuclear palsy and Alzheimer's disease.

The pattern of cortical and subcortical neuropathologic lesions in corticobasal degeneration (CBD) should predict a specific cognitive profile in this disease. To characterize this profile and to determine its specificity by comparison with progressive supranuclear palsy (PSP) and senile dementia of the Alzheimer's type (SDAT), we used an extensive neuropsychological battery assessing global efficiency, executive functions, various tests of encoding and retrieval, dynamic motor organization, and upper limb praxis. We compared the performance of patients with CBD (n = 15) with that of controls (n = 19) matched for age and education, and with that of patients with PSP and SDAT (15 in each group), matched for severity of dementia and depression. Patients with CBD showed: (1) a moderate global deterioration; (2) a dysexecutive syndrome similar to that of patients with PSP and more severe than in SDAT; (3) explicit learning deficits, without retention difficulties and easily compensated by using the same semantic cues at encoding and retrieval as in PSP; this was in contrast with SDAT where cued recall and recognition were also impaired; (4) disorders of dynamic motor execution (temporal organization, bimanual coordination, control, and inhibition) similar to those of patients with PSP and not in SDAT; (5) asymmetric praxis disorders (posture imitation, symbolic gesture execution, and object utilization) that were not observed in PSP or SDAT. Patients with CBD show a specific neuropsychological pattern associating a dysexecutive syndrome, likely due to degeneration of the basal ganglia and prefrontal cortex, and asymmetric praxis disorders, which might be related to premotor and parietal lobe lesions. This neuropsychological profile may help to distinguish this condition clinically from other neurodegenerative diseases.

Aged↗
PubMed1995

Do cognitive changes of Parkinson's disease result from dopamine depletion?

Cognitive changes have long been observed in patients with Parkinson's disease: visuo-spatial deficits, memory disorders, dysexecutive syndrome. Given the modulatory role of the basal ganglia and related structures, these deficits might result from more fundamental disorders concerning the allocation of attentional resources, the temporal organization of behavior, the maintenance of representations in working memory or the self-elaboration of internal strategy, all of which resemble dysfunctions of processes that are commonly considered to be controlled by the frontal lobes. This suggests a functional continuity between the basal ganglia and association areas of the prefrontal cortex. The recent description in primates of parallel, segregated loops that interconnect well defined subregions of the basal ganglia to discrete areas of the prefrontal cortex via the thalamus may give some support to this hypothesis.

Cerebral Cortex↗
PubMed1994

Eye movements in parkinsonian syndromes.

Eye movements were recorded in 14 patients with Parkinson's disease (PD) in the "off" condition, 14 patients with striatonigral degeneration (SND), 10 patients with corticobasal degeneration (CBD), and 10 patients with progressive supranuclear palsy (PSP), with comparison with 12 control subjects. Vertical saccade paralysis was not observed in the PD, SND, and CBD groups but was present in 9 patients of 10 in the PSP group. In the PD and SND groups, horizontal reflexive visually guided saccade latency and accuracy were similar, and differed only slightly from those of controls. In the CBD group, saccade latency was significantly increased and correlated to an "apraxia score"; whereas, in the PSP group, saccade amplitude was significantly decreased. Thus, the abnormalities of both horizontal saccade parameters in the PSP group contrasted with those observed in the CBD group. The percentage of errors in the antisaccade task, an index of prefrontal dysfunction, was markedly increased only in the PSP group. The smooth pursuit gain was decreased in all groups but more severely in the PSP group. It may be concluded that saccade abnormalities are clearly different in SND, CBD, and PSP, and might help in early differential diagnosis in individual patients, but that SND cannot be differentiated from PD on the simple basis of eye movement abnormalities.

Aged↗