Cortically Evoked Movement in Humans Reflects History of Prior Executions, Not Plan for Upcoming Movement

Area of Science:

• Neuroscience
• Motor Control
• Human Motor Behavior

Background:

• Human motor behavior relies on both planning and execution of actions.
• Physiological biases can be induced by intensive, direction-specific movement repetition.
• The influence of movement execution versus planning history on these biases remains unclear.

Purpose of the Study:

• To investigate whether physiological biases result from movement execution or planning history.
• To differentiate the effects of recent execution and plan histories on motor biases.
• To determine if transcranial magnetic stimulation (TMS)-evoked movements reflect ongoing motor planning.

Main Methods:

• Separately manipulated recent movement execution and planning histories in 40 participants.
• Assessed physiological biases using TMS-evoked movements.
• Evaluated default movement plans using a timed-response task.

Main Results:

• Recent movement execution history significantly affected physiological biases.
• Movement planning history influenced the default plan but not TMS-evoked movements during preparation.
• TMS-evoked movements did not bias towards the most frequent plan during preparation.

Conclusions:

• Physiological biases appear to reflect the default state of primary motor cortex activity, not ongoing motor planning.
• Evoked movements may not be a direct readout of neural activation related to voluntary movement planning.
• Findings question the relevance of cortically evoked physiological biases to voluntary movement execution.