Sensitivity to Instruction Strategies in Motor Learning Is Predicted by Anterior-Posterior TMS Motor Thresholds

Area of Science:

• Neuroscience
• Motor Learning
• Human Motor Control

Background:

• Exogenous explicit knowledge's impact on motor learning is variable, potentially linked to sensorimotor network excitability.
• Transcranial magnetic stimulation (TMS) studies indicate anterior-posterior (AP) current interneuron recruitment variability correlates with premotor-motor functional connectivity.

Purpose of the Study:

• To investigate the interaction between AP-sensitive interneuron excitability and explicit knowledge in motor learning using controllable pulse parameter TMS (cTMS).
• To assess how targeted neural stimulation influences sequence-specific learning and general sensorimotor efficiency.

Main Methods:

• Seventy-two participants were categorized into AP-positive and AP-negative groups based on AP threshold.
• A narrow (30 µs) stimulus targeted long-latency corticospinal inputs.
• Participants performed a visuomotor tracking task, with half receiving explicit sequence knowledge; performance assessed sensorimotor efficiency and sequence learning.

Main Results:

• AP30-positive participants (with/without explicit knowledge) and AP30-negative participants without explicit knowledge showed similar sensorimotor efficiency improvements via offline consolidation.
• AP30-negative participants receiving explicit instruction demonstrated significantly reduced sensorimotor efficiency gains, primarily due to impaired offline consolidation.

Conclusions:

• Low excitability in long-latency AP-sensitive inputs may increase vulnerability to explicit instruction interference during motor learning.
• Individual differences in interneuron excitability are crucial for developing effective motor learning instructional strategies.