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Modulation of lemniscal input during conditioned arm movements in the monkey
C E Chapman1, W Jiang, Y Lamarre
1Centre de Recherche en Sciences Neurologiques, Université de Montréal, Québec, Canada.
Experimental Brain Research
|January 1, 1988
Summary
Sensory transmission in the brainstem and thalamus is suppressed before and during movement. This sensory gating mechanism, crucial for motor control, is most pronounced at the somatosensory cortex level.
Area of Science:
- Neuroscience
- Sensory Physiology
- Motor Control
Background:
- Sensory information processing is critical for motor control.
- The lemniscal system plays a key role in transmitting somatosensory information.
- Understanding sensory modulation during movement is essential for explaining motor behavior.
Purpose of the Study:
- To investigate the modulation of sensory transmission in the lemniscal system during a motor task.
- To determine the neural sites and time course of sensory suppression.
- To examine the role of reafferent feedback in sensory gating.
Main Methods:
- Electrophysiological recordings in monkeys performing an elbow flexion task.
- Stimulation of peripheral sensory pathways and central lemniscal/thalamic pathways.
- Simultaneous recordings from medial lemniscus, ventral posterior lateral nucleus (VPLc), and somatosensory cortex.
Main Results:
- Evoked responses to peripheral stimulation were depressed before and during active movement at all recorded levels.
- Cortical responses to central stimulation decreased during movement, but not before.
- Passive movement also decreased sensory transmission, except at the lemniscal level.
Conclusions:
- Centrally mediated suppression of somatosensory transmission occurs before and during movement, starting at the dorsal column nuclei.
- Reafferent signals from moving limbs contribute to reduced transmission at the thalamocortical level during movement.
- This sensory gating mechanism optimizes sensory processing for ongoing motor activity.