Spinal cord contributes to long-term motor learning

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Ali Khatibi, Senior Research Fellow in Pain and Neuroplasticity

Motor learning is one of the most essential but overlooked skills in our daily life. From the way we walk to the way we eat and work with mobile phones, computers, and other tools, motor learning is involved in all of them. Several studies have provided evidence supporting neuroplastic changes in the human brain following the development of new motor skills. They suggest changes in the functioning and connectivity in several regions, including but not limited to the motor cortex, basal ganglia, and cerebellum. In most traditional models, the spinal cord has been regarded as a pathway for conveying signals between the periphery and the brain. However, evidence from neurosychophysiological studies suggest active involvement of the spinal cord in the processing of signals. For example, the gate control theory suggests that the first processing stage for nociceptive signals is at the dorsal horn in the spinal cord.

We are interested in examining the role of the human spinal cord in long-term motor learning. We have used functional magnetic resonance imaging (fMRI) to explore the interaction between the brain and the spinal cord during motor sequence learning. In the first study, now published in PlosBiology, we provided a proof of principle suggesting that fMRI can be used to investigate functional connectivity between the brain and the spinal cord in humans. Detailed information about the acquisition protocol (simultaneous imaging of the brain and the spinal cord) and the pipeline for the preprocessing and analysis has been included in the publication.

Then, we invited healthy, young participants to perform motor sequence learning and training in the lab. Four targets were presented on the screen and using a joystick, participants had to move the cursor to touch the target, which had changed colour. There were sequence blocks and random blocks. Participants were scanned before, during, and after each training block on the first day of training. For four consecutive days, they came to the lab and practised sequence learning (15 blocks, 60 trials each).

Analysis of participants’ performance demonstrated improved learning during each session and from one session to the next. Between sessions, improvement was only observed in sequence practice and not random practice.

Analysis of the brain and spinal cord fMRI data suggested the involvement of distinguished networks contributing to motor learning at early vs late stages of learning in the brain and spinal cord. At the early stages of learning, there was a higher association between C7-8 cord segments and cerebellum, superior parietal lobule and the premotor cortex. There was an association between the activity in the C6 segment of the cord and the Angular gyrus in the late stages.

The findings of our study suggest changes in the dynamic interaction between the brain and the spinal cord when transiting from short-term to long-term learning. Furthermore, they suggest more automated practice comes with less involvement of the cerebral areas involved in voluntary control of movement.

To read more about our research please see the following article:

Khatibi et al., (2022). Brain-spinal cord interaction in long-term motor sequence learning in human: An fMRI study. Neuroimage (253). 119111

https://www.sciencedirect.com/science/article/pii/S1053811922002397

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