The ability to assess muscular force in asymmetrical Parkinson's disease

Centre de Neuroscience Cognitive, CNRS, Bron, France.
Cortex (Impact Factor: 5.13). 02/2008; 44(1):82-9. DOI: 10.1016/j.cortex.2005.11.001
Source: PubMed


We tested the ability of eight Parkinson's disease (PD) patients with clearly asymmetrical right-sided motor signs and eight control subjects to assess different levels of muscular forces. In Experiment 1, subjects had first to produce a target-force with one hand (the reference hand) with the assistance of visual feedback, and then match that force with the other hand (the matching hand) without any visual feedback. In Experiment 2, they had to produce a target-force with one hand and then estimate it by attributing a numerical value. In Experiment 1, the results showed that PD patients could normally reach the target-forces with the more affected left hand but they were impaired in inter-manual force transfer. They were also impaired, in Experiment 2, in estimating forces produced by their more affected hand. Our findings suggest that PD patients present a deficit in sensing motor effort. Effort awareness might be mediated by the basal ganglia.

Download full-text


Available from: Gilles Lafargue,
  • [Show abstract] [Hide abstract]
    ABSTRACT: Dans le présent article, après avoir présenté les mécanismes neurocognitifs impliqués dans la production et la perception de l’effort moteur, nous nous interrogeons sur leur rôle possible dans l’agentivité, le processus cognitif par lequel un individu sait que c’est bien lui qui agit lorsqu’il agit. Nous suggérons qu’un agent se reconnaît comme l’initiateur de ses propres actes, avant tout, dans la mesure où il est capable d’appréhender consciemment l’effort qu’il fournit lors-qu’il agit. Nous présentons également des données expérimentales qui suggèrent que les patients schizophrènes ont une expérience consciente anormale de l’effort volontaire, combinée avec d’autres anomalies de la conscience des actes intentionnels, tout particulièrement ceux qui sont parfois amenés à croire fermement que certains de leurs actes ou pensées sont initiés par des forces étrangères à eux. Les données que nous exposons soutiennent les théories selon lesquelles les croyances délirantes sont une conséquence directe d’expériences perceptives conscientes anormales. Centrally generated signals from premotor areas play a key role in voluntary muscle force perception. Indeed, sensations of effort, rather than sensations of intramuscular tension, make it possible to evaluate the intensity of willed muscle forces. We suggest that the sense of effort is involved in agency, the cognitive process by which one is aware of one’s actions. We argue that effort awareness accompanies each action and is the key component of the feeling of will. In delusions of alien control, patients with schizophrenia do not recognize some of their acts as their own and are convinced that they are under the control of someone else. Some experimental data suggest that delusions of control are related to an altered awareness of effort and an exaggerated awareness of afferent neural information, caused by neurological disorders in the frontal and parietal lobes. This impairment could lead to the inability to identify the author of an action. In this pathological condition, the cerebral state coding for “I intend to act” might move toward the state coding for “someone else intends to act”, even in the absence of another agent.
    PSN 08/2008; 6(3):137-148. DOI:10.1007/s11836-008-0063-1 · 0.07 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Contemporary experimental research has emphasised the role of centrally generated signals arising from premotor areas in voluntary muscular force perception. It is therefore generally accepted that judgements of force are based on a central sense, known as the sense of effort, rather than on a sense of intra-muscular tension. Interestingly, the concept of effort is also present in the classical philosophy: to the French philosopher Maine de Biran [Maine de Biran (1805). Mémoire sur la décomposition de la pensée (Tome III), Vrin, Paris (1963)], the sense of effort is the fundamental component of self-experience, the landmark of the exercise of the will. In the present review, after a presentation of the nature and neurophysiological bases of effort sensation, we will examine its possible involvement in the neurocognitive process of agency. We will further focus on delusions of alien control in schizophrenic patients. Experimental data suggest that these patients have an abnormal awareness of effort caused by cerebral anomalies in the frontal and parietal lobes.
    Consciousness and Cognition 03/2009; 18(1):277-89. DOI:10.1016/j.concog.2008.05.004 · 2.31 Impact Factor

  • Cortex 05/2009; 45(10):1126-37. DOI:10.1016/j.cortex.2009.04.004 · 5.13 Impact Factor
Show more