Motor learning induces time‐dependent plasticity that is observable at the spinal cord level. (27th March 2020)

• Record Type: Journal Article
• Authors: Giboin, Louis‐Solal; Tokuno, Craig; Kramer, Andreas; Henry, Mélanie; Gruber, Markus
• Is Part Of: Journal of physiology. Volume 598:Number 10(2020)
• Page Start: 1943
• Page End: 1963
• Publication Date: 2020-03-27
• Subjects: acquisition -- balance training -- generalization -- H‐reflex -- postural control -- retention -- specificity; Physiology -- Periodicals; 612.005
• DOI: 10.1113/JP278890
• Languages: English
• ISSNs: 0022-3751

Abstract

Abstract : Key points: The spinal cord is an important contributor to motor learning It remains unclear whether short‐term spinal cord adaptations are general or task‐specific Immediately after task acquisition, neural adaptations were not specific to the trained task (i.e. were general) Twenty‐four hours after acquisition, neural adaptations appeared to be task‐specific The neural reorganization and generalization of spinal adaptations appears to be time‐dependent. Abstract: Spinal cord plasticity is an important contributor of motor learning in humans, although its mechanisms are still poorly documented. In particular, it remains unclear whether short‐term spinal adaptations are general or task‐specific. As a marker of neural changes that are observable at spinal level, we measured the Hoffmann reflex (H‐reflex) amplitude in the soleus muscle of 18 young healthy human adults before, immediately after (acquisition), and 24 h after (retention) the learning of a skilled task (i.e. one‐legged stance on a tilt board). H‐reflexes were elicited 46 ± 30 ms before touching the tilt board. Additionally, and at the same time points, we measured the H‐reflex with the subject sitting at rest and when performing an unskilled and untrained task (i.e. one‐legged stance on the floor). After task acquisition, there was a decrease of the H‐reflex amplitude measured at rest but not during the skilled or the unskilled task. At retention, there was a decrease of the H‐reflex when measured during the skilled task but not during the unskilled task or at rest. Performance increase was not associated with changes in the H‐reflex amplitude. After the acquisition of a new skilled task, spinal changes appeared to be general (i.e. observable at rest). However, 24 h after, these changes were task‐specific (i.e. observable only during performance of the trained task). These results imply that skill training induces a time‐dependent reorganization of the modulation of spinal networks, which possibly reflects a time‐dependent optimization of the feedforward motor command. Key points: The spinal cord is an important contributor to motor learning It remains unclear whether short‐term spinal cord adaptations are general or task‐specific Immediately after task acquisition, neural adaptations were not specific to the trained task (i.e. were general) Twenty‐four hours after acquisition, neural adaptations appeared to be task‐specific The neural reorganization and generalization of spinal adaptations appears to be time‐dependent.