Probing the corticospinal link between the motor cortex and motoneurones: some neglected aspects of human motor cortical function
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Probing the corticospinal link between the motor cortex and motoneurones: some neglected aspects of human motor cortical function. / Petersen, Nicolas Caesar; Butler, Jane E.; Taylor, Janet L.; Gandevia, Simon C.
In: Acta Physiologica (Print Edition), Vol. 198, No. 4, 2010, p. 403-416.Research output: Contribution to journal › Review › Research › peer-review
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TY - JOUR
T1 - Probing the corticospinal link between the motor cortex and motoneurones: some neglected aspects of human motor cortical function
AU - Petersen, Nicolas Caesar
AU - Butler, Jane E.
AU - Taylor, Janet L.
AU - Gandevia, Simon C.
N1 - CURIS 2010 5200 016
PY - 2010
Y1 - 2010
N2 - 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 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) contribute to 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.
AB - 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 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) contribute to 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.
U2 - 10.1111/j.1748-1716.2009.02066.x
DO - 10.1111/j.1748-1716.2009.02066.x
M3 - Review
C2 - 20003100
VL - 198
SP - 403
EP - 416
JO - Acta Physiologica
JF - Acta Physiologica
SN - 1748-1708
IS - 4
ER -
ID: 17112573