Characterizing Evoked Movement Patterns and Connectivity in Sensorimotor Cortex After Sensory Loss in Squirrel...

Area of Science:

• Neuroscience
• Motor Control
• Sensory Systems

Background:

• Skilled hand use relies heavily on sensory feedback (tactile and proprioceptive).
• Sensory loss in the hand leads to initial motor deficits, followed by gradual recovery.
• Understanding how the sensorimotor cortex adapts to sensory loss is crucial for rehabilitation strategies.

Purpose of the Study:

• To investigate the long-term effects of sensory pathway lesions on motor responses evoked by cortical stimulation.
• To determine if sensory deprivation alters motor maps in the primary motor cortex (M1) and somatosensory areas.
• To examine changes in corticocortical connections following sensory loss.

Main Methods:

• Selective lesions of the dorsal column (C5, DCL) in the cervical spinal cord of squirrel monkeys.
• Long-train intracortical microstimulation (LT-ICMS) to evoke forelimb movements from M1 and somatosensory areas (3a, 3b, 1).
• Mapping of somatosensory receptive fields and investigation of corticocortical connections using neuroanatomical tracers.

Main Results:

• After one year of recovery, LT-ICMS-evoked movement maps in M1 and somatosensory areas showed no statistically significant effects of the dorsal column lesion (DCL).
• Results align with previous findings on long-term recovery effects on somatosensory maps and inter-somatosensory area connections.
• While motor responses in somatosensory cortex were minimally affected, corticocortical connections between M1 and somatosensory areas were more widespread.

Conclusions:

• The sensorimotor cortex exhibits significant plasticity, compensating for long-term sensory loss from the hand.
• Evoked motor responses in M1 and deprived somatosensory areas remain largely stable despite sensory deprivation.
• Sensory loss leads to more widespread alterations in corticocortical connectivity rather than changes in evoked motor maps.