Variability in the amplitude of skeletal muscle responses to magnetic stimulation of the motor cortex in man

Ellaway, P H; Davey, Nick J.; Maskill, David; Rawlinson, S.; Lewis, H.S.; Anissimova, N. P.

doi:10.1016/s0924-980x(98)00007-1

Cited by 148 publications

(105 citation statements)

References 36 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Before placement of EMG electrodes, the skin was rubbed with a mildly abrasive material dipped in medical alcohol. The TMS site over the motor cortex was chosen as a hot spot (Traversa et al, 1997;Ellaway et al, 1998) [i.e., the coil location that produced MEPs in biarticular muscles (long heads of biceps and triceps) with the lowest TMS setting at rest]. The coil was oriented at a 45°angle to the midline with the handle pointing posteriorly.…”

Section: Methodsmentioning

confidence: 99%

Descending Corticospinal Control of Intersegmental Dynamics

Gritsenko¹,

Kalaska²,

Cisek³

2011

J. Neurosci.

View full text Add to dashboard Cite

To make an accurate movement, the CNS has to overcome the inherent complexities of the multijoint limb. For example, interaction torques arise when motion of individual arm segments propagates to adjacent segments causing their movement without any muscle contractions. Since these passive joint torques significantly add to the overall torques generated by active muscular contractions, they must be taken into account during planning or execution of goal-directed movements. We investigated the role of the corticospinal tract in compensating for the interaction torques during arm movements in humans. Twelve subjects reached to visual targets with their arm supported by a robotic exoskeleton. Reaching to one target was accompanied by interaction torques that assisted the movement, while reaching to the other target was accompanied by interaction torques that resisted the movement. Corticospinal excitability was assessed at different times during movement using single-pulse transcranial magnetic stimulation (TMS) over the upper-arm region of M1 (primary motor cortex). We found that TMS responses in shoulder monoarticular and elbow-shoulder biarticular muscles changed together with the interaction torques during movements in which the interaction torques were resistive. In contrast, TMS responses did not correlate with assistive interaction torques or with co-contraction. This suggests that the descending motor command includes compensation for passive limb dynamics. Furthermore, our results suggest that compensation for interaction torques involves the biarticular muscles, which span both shoulder and elbow joints and are in a biomechanically advantageous position to provide such compensation.

show abstract

Section: Methodsmentioning

confidence: 99%

Descending Corticospinal Control of Intersegmental Dynamics

Gritsenko¹,

Kalaska²,

Cisek³

2011

J. Neurosci.

View full text Add to dashboard Cite

show abstract

“…We chose to hold the coil by hand to easily compensate for small movements of the participant's head during data collection. Indeed, it has been demonstrated that holding the coil by hand or by a holder induces a comparable MEP variability (Ellaway et al, 1998). Moreover, although image-guided TMS allows for higher resolution of the targeted sites with respect to holding the coil by hand, the two procedures brought about a comparable degree of MEP variability when high, suprathreshold stimulation intensities were used (Gugino et al, 2001).…”

Section: Methodsmentioning

confidence: 99%

Mapping Implied Body Actions in the Human Motor System

et al. 2006

View full text Add to dashboard Cite

The human visual system is highly tuned to perceive actual motion as well as to extrapolate dynamic information from static pictures of objects or creatures captured in the middle of motion. Processing of implied motion activates higher-order visual areas that are also involved in processing biological motion. Imagery and observation of actual movements performed by others engenders selective activation of motor and premotor areas that are part of a mirror-neuron system matching action observation and execution. By using single-pulse transcranial magnetic stimulation, we found that the mere observation of static snapshots of hands suggesting a pincer grip action induced an increase in corticospinal excitability as compared with observation of resting, relaxed hands, or hands suggesting a completed action. This facilitatory effect was specific for the muscle that would be activated during actual execution of the observed action. We found no changes in responsiveness of the tested muscles during observation of nonbiological entities with (e.g., waterfalls) or without (e.g., icefalls) implied motion. Thus, extrapolation of motion information concerning human actions induced a selective activation of the motor system. This indicates that overlapping motor regions are engaged in the visual analysis of physical and implied body actions. The absence of motor evoked potential modulation during observation of end posture stimuli may indicate that the observationexecution matching system is preferentially activated by implied, ongoing but not yet completed actions.

show abstract

“…During the stimulations, the subjects performed a slight symmetrical voluntary contraction of the target muscles to facilitate the response [19,35]. To compensate for the inherent variability of motor evoked potentials [12], 6 to 8 stimuli were given for each muscle and each coil position to collect a representative sample of responses.…”

Section: ■ Stimulationsmentioning

confidence: 99%