Corticospinal control of the thumb-index grip depends on precision of force control: a transcranial magnetic stimulation and functional magnetic resonance imagery study in humans.

Full Abstract

The corticospinal system (CS) is well known to be of major importance for controlling the thumb-index grip, in particular for force grading. However, for a given force level, the way in which the involvement of this system could vary with increasing demands on precise force control is not well-known. Using transcranial magnetic stimulation and functional magnetic resonance imagery, the present experiments investigated whether increasing the precision demands while keeping the averaged force level similar during an isometric dynamic low-force control task, involving the thumb-index grip, does affect the corticospinal excitability to the thumb-index muscles and the activation of the motor cortices, primary and non-primary (supplementary motor area, dorsal and ventral premotor and in the contralateral area), at the origin of the CS. With transcranial magnetic stimulation, we showed that, when precision demands increased, the CS excitability increased to either the first dorsal interosseus or the opponens pollicis, and never to both, for similar ongoing electromyographic activation patterns of these muscles. With functional magnetic resonance imagery, we demonstrated that, for the same averaged force level, the amplitude of blood oxygen level-dependent signal increased in relation to the precision demands in the hand area of the contralateral primary motor cortex in the contralateral supplementary motor area, ventral and dorsal premotor area. Together these results show that, during the course of force generation, the CS integrates online top-down information to precisely fit the motor output to the task's constraints and that its multiple cortical origins are involved in this process, with the ventral premotor area appearing to have a special role.

Learn Faster Today Improve your study skills

Author information

Author/s: Bonnard, M (M); Galléa, C (C); De Graaf, J B (JB); Pailhous, J (J);

Affiliation: Mediterranean Institute of Cognitive Neuroscience, UMR 6193, CNRS-GLM, Université d'Aix-Marseille, Marseille, France. bonnard(-atsign-)incm.cnrs-mrs.fr

Journal and publication information

Publication Type: Journal Article; Research Support, Non-U.S. Gov't

Journal: The European journal of neuroscience (Eur J Neurosci), published in France. (Language: eng)

Reference: 2007-Feb; vol 25 (issue 3) : pp 872-80

Dates: Created 2007/03/01; Completed 2007/05/02;

PMID: 17328782, status: MEDLINE (last retrieval date: 12/26/2008)

Sourced from the National Library of Medicine. Abstract text and other information may be subject to copyright.

External Links for this article (including full text providers, if available):

Click Electronic Full-text Provider Links to see options for finding the electronic full text links to this article. Note there may be a subscription or fee required for access to the full text. See our FAQ for information on finding FREE full text articles.

This article may also be located in paper journal collections available in many libraries. Use the Journal and Publication Information above to find the full article.

MeSH headings (categories)

This article was linked to the MESH Headings shown below.

Adult
Efferent Pathways - physiology
Electromyography
Evoked Potentials, Motor - physiology
Female
Hand Strength - physiology
Humans
Isometric Contraction - physiology

Magnetic Resonance Imaging
Male
Motor Cortex - cytology; physiology
Muscle, Skeletal - innervation; physiology
Oxygen - blood
Pyramidal Tracts - cytology; physiology
Thumb - innervation; physiology
Transcranial Magnetic Stimulation

Associated Chemicals: Oxygen (7782-44-7)

These are the highest related articles currently in the database:

See 100+ related articles.