Experts have discovered that the brain separates the order and timing of movements in complex sequences before zipping and transferring them into specific movement commands, or “muscle memory,” as the person begins the action.
According to the new study, the human brain prepares skilled movements such as dancing, playing the guitar, and performing athletic feats, by “zipping and unzipping” information about the timing and order of movements prior to the action.
University of Birmingham and Bangor University researchers believe their discovery could improve motor rehabilitation for stroke patients.
They found that high-level sequencing of movement, such as order and timing, can be stored across multiple motor areas of the brain, often after several days of training and memorization of action sequences, before being activated in response to a specific trigger such as a musical cue or a starting gun.
Information State Shifts
The ability to execute a series of actions from memory is a defining characteristic of skilled human behaviour, whether it be handwriting or playing an instrument.
“What is surprising is that the brain separates these skills into their constituent features rather than encoding them as an integrated muscle memory, even after extensive training. There is a shift in information states within the brain when performing such tasks,”
said principal investigator Dr. Katja Kornysheva, from the Center for Human Brain Health at the University of Birmingham.
When we prepare information for execution, we unzip it from memory before zipping everything back together to begin the task. If we need to change the speed or timing of an upcoming action, for example, this unzipping mechanism may help us remain adaptable for adjustments even in the final hundreds of milliseconds before we start the movement.
Timing Control and Order Flexibility
Excluding professional musicians, a series of almost 1,000 trials saw right-handed participants learn and memorize four keyboard sequences they prepared and produced in response to a visual cue.
Following training, participants performed the keyboard sequences in an MRI scanner, which measured activity patterns across the brain as they performed the task. The absence of the go cue on some trials allowed the researchers to separate preparation from the movement itself.
Researchers also discovered several brain regions that control timing during movement production, but none appeared to control order independently of timing.
“There was a matching effect in our participants’ behavior; they were faster in acquiring a sequence with a new order of finger presses when they were familiar with the timing yet struggled to learn a sequence when they had to pair a previously trained order with a new timing. Perhaps timing control staying active during production allows for flexibility even after the movement has started,”
said first author Rhys Yewbrey, from Bangor University.
According to the researchers, the brain separates sequence order and timing as “what” elements representing higher-level control, which are combined to define “how” the task should be performed.
These new findings help us understand how skilled actions for everyday skills like typing, tying shoelaces, and playing a musical instrument are stored and controlled in the brain, and what makes them flexible and resilient to changes in the environment or neurological disorders.
Reference:
- Rhys Yewbrey, Myrto Mantziara, Katja Kornysheva. Cortical patterns shift from sequence feature separation during planning to integration during motor execution. Journal of Neuroscience 1 February 2023, JN-RM-1628-22; DOI:10.1523/JNEUROSCI.1628-22.2023