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Luc Defebvre

Publications and source records attributed to Luc Defebvre.

7 recordsLinked to original sources
PubMed2004

Deficits in decoding emotional facial expressions in Parkinson's disease.

INTRODUCTION: The basal ganglia have numerous connections not only with the motor cortex but also with the prefrontal and limbic cortical areas. Therefore, basal ganglia lesions can disturb motor function but also cognitive function and emotion processing. The aim of the present study was to assess the consequences of Parkinson's disease (PD) on ability to decode emotional facial expressions (EFEs)-a method commonly used to investigate non-verbal emotion processing. METHODS: Eighteen PD patients participated in the study, together with 18 healthy subjects strictly matched with respect to age, education and sex. The patients were early in the course of the disease and had not yet received any antiparkinsonian treatment. Decoding of EFEs was assessed using a standardized, quantitative task where the expressions were of moderate intensity, i.e. quite similar to those experienced in everyday life. A set of tests also assessed executive function. Visuospatial perception, depression and anxiety were measured. RESULTS: Early in the course of the disease, untreated PD patients were significantly impaired in decoding EFEs, as well as in executive function. The deficits were significantly interrelated, although neither was significantly related to severity of the motor symptoms. Visuospatial perception was not impaired, and the patients' impairment was related neither to their depression nor to their anxiety score. The PD patients' impairment in decoding EFEs was related to a systematic response bias. CONCLUSION: Early in the course of PD, non-verbal emotional information processing is disturbed. This suggests that in PD, nigrostriatal dopaminergic depletion leads not only to motor and cognitive disturbances but also to emotional information processing deficits. The observed correlation pattern does not enable adoption of a clear-cut position in the debate over totally or partially segregated functional organization of the basal ganglia circuits.

Aged↗
PubMed2003

Effects of subthalamic nucleus stimulation and levodopa treatment on gait abnormalities in Parkinson disease.

BACKGROUND: Stimulation of the subthalamic nucleus is proposed for the treatment of patients presenting with severe Parkinson disease. The effect on gait is not clearly established. OBJECTIVES: To evaluate objectively the influence of bilateral subthalamic nucleus stimulation on gait in Parkinson disease and to compare it with the effects of levodopa treatment. METHODS: Ten patients underwent bilateral subthalamic nucleus stimulation. The preoperative and postoperative (3 months after surgery) clinical gait disturbances, as well as spatial and temporal gait parameters, were analyzed in off and on-drug conditions. The gait analysis was performed using a video motion analysis system (optoelectronic VICON system; Oxford Metrics, Oxford, England). RESULTS: In the off condition, there was an improvement after surgery for the total motor score and the gait subscore. In the on-drug condition, there was an improvement in levodopa-induced dyskinesias and the motor score, whereas the gait subscore was unchanged. For the gait parameters measured by the video motion analysis system system, there was also an improvement in the off condition and to a lesser extent in the on-drug condition. CONCLUSIONS: Our method allowed exact quantification of the benefit of surgery on gait parameters. Compared with the levodopa treatment, the effect of stimulation on gait kinematic parameters seems to be qualitatively similar but quantitatively different with a lower benefit on gait velocity and stride length. Concerning the pathophysiology of gait troubles in Parkinson disease, the deficit in control of stride length would be the fundamental deficit. The study underlines the possible role of the subthalamic nucleus on the stride length regulation.

Antiparkinson Agents↗
PubMed2003

Executive function differences in multiple system atrophy and Parkinson's disease.

The aim of the present study was to assess executive function in patients with multiple system atrophy (MSA) and Parkinson's disease (PD) looking for specific differences and considering motor disability and disease duration. Performance of 11 MSA patients was compared to that of 12 healthy controls and two groups of 12 PD patients, one matched with respect to the severity of motor symptoms and the other with respect to disease duration. Compared to healthy controls, MSA and PD patients both presented executive dysfunction but, in MSA, the impairment was more severe and diffuse. This study suggests that despite the evidence of some differences in executive function in MSA and PD, the contribution of standard neuropsychological examination to the differential diagnosis of both syndromes remains still limited.

Adult↗
PubMed2002

[Anticipatory postural adjustments associated with arm flexion: interest of vertical torque].

OBJECTIVE: To find a biomechanical parameter able to characterize postural adjustments in different movement conditions. METHODS: The arm-raising movement performed during the upright human position imposes a vertical torque (Tz) that can be measured by a force plate-form. This torque was studied in ten healthy young subjects with opto electronic system Vicon 370. The subjects stood on a force platform, performed shoulder flexion of their right arm, to grasp a handle in front of them, in five conditions : self-paced at 3 different velocities (slow, medium, maximal), triggered by an auditory signal, loaded (1 kg attached to the wrist), all at maximal velocity. In a sixth condition, the arm was passively displaced by an experimenter. RESULTS: Tz displayed a negative phase (counter-clock wise body rotation) in all conditions. A positive phase occurred prior to the negative one, and preceded movement onset only if the movement was voluntary. In the triggered condition, the positive phase of Tz was delayed (- 60 ms) compared to the self-paced condition at maximal velocity (- 155 ms). However Tz onset latency was modified neither by load nor velocity. Tz amplitude increased with increasing velocity, load and in a reaction time condition. CONCLUSIONS: The vertical torque Tz, especially its positive phase gives useful informations about the latency, duration and intensity of the postural preparation related to a voluntary movement, according to the movement parameters. Tz is therefore able to characterise postural adjustments in all conditions, even with low movement velocity.

Adaptation, Physiological↗
PubMed2002

Relationship between oscillations in the basal ganglia and synchronization of cortical activity.

The functions of oscillations within the basal ganglia are poorly understood. We discuss in the present paper, the possible physiological or pathological roles of oscillatory activities within the basal ganglia, and their relationship to cortical oscillations. Three aspects are presented: 1. What do we know from animal studies? 2. What do we know from neurophysiological studies in parkinsonian patients? 3. What is the effect of L-dopa treatment and electrical stimulation within basal ganglia circuits on cortical oscillations? Animal studies suggest that neuronal oscillations are spontaneously generated within the basal ganglia system, especially from the GPE and the subthalamic nucleus (STN), but are mainly synchronized by cortical activity via the striatal inputs. Dopamine depletion results in a global increase of oscillations within the whole basal ganglia system, particularly in the GP-NST network. Oscillations within the basal ganglia may, in part, be related to tremor since they are enhanced, especially in the globus pallidus internus (GPI) and the STN, in human and animal dopaminergic depletion. However, they also play a role in the physiology of movement as revealed by coherence analysis between cortex, muscles and GPI/STN in parkinsonian patients undergoing deep brain stimulation. It is known that the basal ganglia may influence cortico-muscular oscillations such as the Piper rhythm and other rhythms in the beta band. In off-drug parkinsonian patients, low frequency oscillations (4-10 Hz) are favoured, presumably resulting in bradykinesia and low force. When medically (Ldopa) or surgically (deep brain stimulation) treated, these low frequency oscillations are replaced by high frequency (70 Hz) oscillations that are important for motor programs to be correctly executed. Studies of cortical reactivity related to planning of voluntary movement in parkinsonian patients provide evidence that it is possible to influence cortical reactivity through the basal ganglia system.

Animals↗
PubMedDate not supplied

[Motor complications in dopa treatment of parkinson disease: clinical description and evaluation].

The aim of this study was to present the clinical characteristics of and the evaluation methods for the motor complications sometimes observed in the early stages of Parkinson's disease, differentiating motor fluctuations and levodopa-induced dyskinesias. The most common forms of motor fluctuations are the predictable end-of-dose deterioration (wearing off), the early-morning akinesia, and the on-off phenomenon. Non-motor fluctuations are often associated with different symptoms: dysautonomia, pain, psychic or cognitive signs during off periods and sometimes also during on periods. Levodopa-induced dyskinesias are classified according to their temporal profile after drug administration, namely peak-dose dyskinesias (mainly choreic movements), biphasic dyskinesias--onset and end-of-dose--(mainly dystonic and ballic movements), and finally off-period dyskinesias (dystonic movements). Clinical evaluation of motor complications must be performed precisely to establish the best therapeutic strategy.

Antiparkinson Agents↗