Cortical Patterns Shift from Sequence Feature Separation during Planning to Integration during Motor Execution.

Area of Science:

• Neuroscience
• Motor Control
• Cognitive Neuroscience

Background:

• Skilled motor behavior, such as handwriting or playing music, involves performing sequences of movements from memory.
• Previous research identified tuning in motor, premotor, and parietal regions for sequence features like order and timing.
• The dynamic unfolding of this tuning across planning and execution phases remained largely unknown.

Purpose of the Study:

• To investigate how cortical tuning to motor sequence features dynamically changes between planning and execution.
• To differentiate the neural representation of sequence order and timing during preparation versus production.
• To understand the neural basis of flexible adaptation in skilled motor sequences.

Main Methods:

• Trained 24 healthy participants to produce five-element finger press sequences from memory.
• Utilized a delayed sequence production paradigm with functional magnetic resonance imaging (fMRI).
• Analyzed local cortical fMRI patterns during preparation (No-Go trials) and production (Go trials) to distinguish perimovement phases.

Main Results:

• During planning, premotor and parietal areas showed increased tuning to either movement order or timing independently.
• During execution, these regions exhibited patterns integrating both sequence order and timing features.
• Timing-specific tuning was observed in ventral premotor, supplementary motor, and superior parietal areas during execution.

Conclusions:

• A state shift occurs from feature separation during planning to feature integration during execution in motor cortical networks.
• This neural dynamic supports the behavioral transfer of learned timing but not order to new sequence combinations.
• Findings suggest a hierarchical control mechanism where sequence features are compiled dynamically for flexible motor output.