Synaptic linkages between red nucleus cells and limb muscles during a multi-joint motor task.
The magnocellular red nucleus (RNm) becomes highly active when a monkey reaches to grasp an object. However, the only spike-triggered averaging studies of the RNm to date have been restricted to a simple wrist tracking paradigm and electromyographic (EMG) measurements of muscles of the forearm. We have now measured EMG signals from a large number of muscles throughout the shoulder, arm, forearm, and hand during a variety of tasks, including unconstrained reaching and grasping movements. Relations between these EMG signals and single-unit activity were assessed by on-line spike-triggered averaging and revealed significant post-spike effects among muscles of the shoulder and proximal arm, as well as intrinsic hand muscles. Although there remained a strong bias toward the extensor muscles of the forearm, as has been shown earlier, these results reinforce the importance of the RNm in the control of coordinated, whole-limb reaching movements.
Sinkjaer
T
T
Department of Physiology, Northwestern University Medical School, Chicago, IL 60611, USA.
Miller
L
L
Andersen
T
T
Houk
J C
JC
D000818:Animals; D001933:Brain Stem / Q000502:physiology; D004567:Electrodes, Implanted; D004576:Electromyography; D005542:Forearm / Q000294:innervation / Q000502:physiology; D007596:Joints / Q000502:physiology; D008253:Macaca mulatta; D009046:Motor Neurons / Q000502:physiology; D009068:Movement / Q000502:physiology*; D018482:Muscle, Skeletal / Q000294:innervation / Q000502:physiology*; D012012:Red Nucleus / Q000166:cytology / Q000502:physiology*; D013569:Synapses / Q000502:physiology*