A common structure underlies low-frequency cortical dynamics in movement, sleep, and sedation

Area of Science:

• Neuroscience
• Motor Control
• Computational Neuroscience

Background:

• Upper-limb movements often comprise regular submovements.
• Neural correlates of submovement frequencies (1-4 Hz) are observed in the motor cortex.
• Movement timing is typically attributed to extrinsic factors like biomechanics and feedback delays.

Purpose of the Study:

• To investigate the potential contribution of intrinsic neural rhythmicity to the temporal profile of upper-limb movements.
• To explore cyclic activity in the motor cortex during isometric movement tasks.
• To determine if cortical dynamics related to movement are also present during non-behavioral states.

Main Methods:

• Multielectrode recordings were performed in monkeys during an isometric movement task.
• Cortical activity was analyzed during ketamine sedation and natural sleep.
• Cyclic activity and oscillations in primary motor cortex and premotor cortex were identified.

Main Results:

• Cyclic activity locked to submovements was revealed in the primary motor cortex.
• A distinct oscillation was identified in the premotor cortex.
• Similar cortical cycles and inter-areal synchronization were observed during sedation and sleep, independent of overt movement.

Conclusions:

• The motor networks controlling the upper limb possess intrinsic periodicity at submovement frequencies.
• This intrinsic periodicity is reflected in the speed profile of movements.
• Cortical dynamics coupled to submovements are also present in the absence of behavior, indicating an internal rhythmicity.