Neural populations in the dorsal and ventral cervical spinal cord share temporal dynamics during reach

Recent research on neural population dynamics in the spinal cord has shed light on the shared temporal patterns during reaching movements. Traditionally, motor cortex function has been a focal study area, employing neural population dynamics as a framework. However, the extent to which these dynamics reflect stage-specific computations or are shared across input and output stages within a sensorimotor circuit remains unclear.

The spinal cord, with its segregation of afferent inputs and motor outputs by anatomical depth, presented an opportunity to explore this question directly.

To address this, researchers developed depth-resolved Neuropixels recordings from the rat cervical spinal cord during targeted reaching behavior. Across the recordings, the population activity was found to be low-dimensional and organized into transient, rotational, and target-specific dynamical motifs. Despite variations in single-neuron activity between depths, both dorsal and ventral populations exhibited nearly identical dynamics across different targets and animals.

A striking finding was the striking synchronization of the dominant target-invariant component across depths, while other components, including the target-specific component, demonstrated condition-dependent ventral-to-dorsal delays. These delays were found to be consistent with movement-related feedback, suggesting that cervical spinal population dynamics span both sensory and motor territories.

The study concludes that these dynamics may reflect shared coordination of activity rather than purely state-specific local processing within the spinal cord.