The human hand combines well-established motor skills with remarkable flexibility in adapting to task demands.
However, the underlying mechanisms through which the brain balances stability and flexibility remain largely unknown. In the absence of external input or behavior, spontaneous (intrinsic) brain connectivity is thought to represent a form of pre-existing memory.
In this study, we investigated how manual dexterity modulates spontaneous functional connectivity in the motor cortex during hand movement. Using magnetoencephalography (MEG) in 47 human participants (both sexes), we examined connectivity modulations in the α and β frequency bands at rest and during two motor tasks (i.e., finger tapping and toe pressing).
The flexibility and stability of these modulations allowed us to identify two groups of participants with different performance levels (high and low performers) in the Nine-Hole Peg Test, a standard measure of manual dexterity.
In the α band, participants with higher manual dexterity exhibited widespread decreases in connectivity—specifically within the motor cortex—along with increased segregation and reduced nodal centrality. Participants with lower manual dexterity showed the opposite pattern.
Remarkably, these brain-to-behavior relationships were mirrored by behavior-to-brain analyses: when participants were divided based on their median dexterity score, the same connectivity patterns emerged.
In summary, this experiment demonstrates that a long-term motor skill—manual dexterity—shapes how motor systems respond during movement.
