Probing the corticospinal link between the motor cortex and motoneurones: some neglected aspects of human motor cortical function

Authors: Petersen, N. C.1; Butler, J. E2; Taylor, J. L2; Gandevia, S. C.2

Source: Acta Physiologica, Volume 198, Number 4, April 2010 , pp. 403-416(14)

Publisher: Wiley-Blackwell

Buy & download fulltext article:

OR

Price: $48.00 plus tax (Refund Policy)

Abstract:

Abstract

This review considers the operation of the corticospinal system in primates. There is a relatively widespread cortical area containing corticospinal outputs to a single muscle and thus a motoneurone pool receives corticospinal input from a wide region of the cortex. In addition, corticospinal cells themselves have divergent intraspinal branches which innervate more than one motoneuronal pool but the synergistic couplings involving the many hand muscles are likely to be more diverse than can be accommodated simply by fixed patterns of corticospinal divergence. Many studies using transcranial magnetic stimulation of the human motor cortex have highlighted the capacity of the cortex to modify its apparent excitability in response to altered afferent inputs, training and various pathologies. Studies using cortical stimulation at ‘very low’ intensities which elicit only short-latency suppression of the discharge of motor units have revealed that the rapidly conducting corticospinal axons (stimulated at higher intensities) drive motoneurones in normal voluntary contractions. There are also major non-linearities generated at a spinal level in the relation between corticospinal output and the output from the motoneurone pool. For example, recent studies have revealed that the efficacy of the human corticospinal connection with motoneurones undergoes activity-dependent changes which influence the size of voluntary contractions. Hence, corticospinal drives must be sculpted continuously to compensate for the changing functional efficacy of the descending systems which activate the motoneurones. This highlights the need for proprioceptive monitoring of movements to ensure their accurate execution.

Keywords: corticomotoneuronal; corticospinal; motor control; motor cortex; motorneurone; transcranial magnetic stimulation

Document Type: Research Article

DOI: http://dx.doi.org/10.1111/j.1748-1716.2009.02066.x

Affiliations: 1:  Departments of Exercise and Sport Sciences, and Neuroscience and Pharmacology, University of Copenhagen, Copenhagen, Denmark 2:  Prince of Wales Medical Research Institute, University of New South Wales, Sydney, NSW, Australia

Publication date: April 1, 2010

Related content

Tools

Key

Free Content
Free content
New Content
New content
Open Access Content
Open access content
Subscribed Content
Subscribed content
Free Trial Content
Free trial content

Text size:

A | A | A | A
Share this item with others: These icons link to social bookmarking sites where readers can share and discover new web pages. print icon Print this page