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The processing of human ballistic movements explored by stimulation over the cortex
E Palmer1, E Cafarelli, P Ashby
1Playfair Neuroscience Unit, University of Toronto, Toronto Western Hospital, Ontario, Canada.
The Journal of Physiology
|December 1, 1994
Summary
Rapid arm movements and associated postural adjustments are preprogrammed and initiated similarly. Both motor cortices release these movements to spinal motoneurons upon receiving a
Area of Science:
- Neuroscience
- Motor Control
- Human Physiology
Background:
- Understanding the neural mechanisms underlying rapid voluntary movements and associated postural adjustments is crucial for motor control research.
- Previous studies suggested distinct control pathways for focal movements and postural responses.
Observation:
- Rapid arm abduction elicits a triphasic electromyographic (EMG) pattern in prime movers (deltoid, latissimus dorsi) and bilateral muscle activity for postural adjustments.
- Transcranial magnetic stimulation over the motor cortex delayed EMG bursts in contralateral postural muscles and ipsilateral prime movers, indicating cortical involvement.
- This delay was most pronounced when stimulation preceded the expected EMG burst, suggesting pre-motor cortical processing.
Findings:
- Focal ballistic movements and associated postural adjustments share identical generation mechanisms.
- These movements are preprogrammed and released from memory via bilateral motor cortex pathways to spinal motoneurons.
- Motor cortex stimulation inhibits voluntary movement initiation without affecting spinal motoneuron excitability.
Implications:
- The findings support a unified preprogramming model for both focal movements and postural adjustments.
- This research provides insights into the neural basis of coordinated limb and trunk movements.
- Understanding these mechanisms can inform rehabilitation strategies for motor disorders.