Exercise-Induced Upregulation of M1 Excitability Following Motor Practice Does Not Predict Procedural Consolidation

Abstract

A brief bout of moderate intensity cardiovascular exercise immediately after procedural learning can protect a newly acquired motor memory from interference. The present experiment examined the possibility that exercise after practice increases motor cortex (MCE) which has been argued to be a biomarker for procedural skill consolidation. PURPOSE: Examine if (a) offline gain in procedural skill is associated with elevated MCE following practice and (b) the MCE following practice can be modified via exercise. METHODS: 35 right handed young adults were assigned to an Interference (INT), Interference + Exercise (INT+EX), or a no interference, no exercise (NO) condition. All individuals practiced a target motor sequence and some (INT, INT+EXE) performed additional training with an alternative motor sequence 2-hr after practice with the target. The INT+EXE also included cardiovascular exercise the target sequence practice. Test performance of the target sequence occurred 6-hr after practice. MCE was assessed using transcranial magnetic stimulation prior to training and after training (every 3 min for a total of 11 post training assessments of MCE). RESULTS: One way ANOVA (Condition: INT, INT+EXE, NO) was used to analyze the mean response time for the target sequence offline learning effect and revealed a main effect of Condition F (1,32)=17.01, p<0.01.The extra practice in INT led to significant forgetting (-3±7ms) compared to the NO condition (NO, +21±7ms). Introducing exercise, despite the presence of interference, eliminated the forgetting observed for the INT condition (INT+EXE, 30±7ms). A 3 (Condition: INT, INT+EXE, NO) x 11(Time: 1-11) ANOVA with repeated measures on the last factor conducted on the % change in the normalized CE failed to reveal any significant main or interaction effects (F’s < 1.0). CONCLUSION: The INT+EXE condition resulted in relatively greater increase in M1 excitability after practice compared to INT and NO conditions but this increase was not significant. Moreover, relative increase in M1 excitability did not predict the extent of procedural learning at the time of test. These data question the claim that an upregulation of excitability at M1 is a biomarker for procedural skill consolidation.