Motor performance recovery after deterioration due to central fatigue does not reflect primary motor cortex (M1) excitability, but the neural bases of this phenomenon are unknown.

To address this issue, we explored with fMRI the brain activation areas elicited in 14 healthy volunteers during a demanding motor task performed with the right (dominant) hand, based on the repetition of a finger-thumb opposition sequence (index, medium, ring and little) acoustically-paced at 2 Hz. The experimental protocol investigated different conditions: baseline, demanding finger motor task after 5-min motor sequence execution, and motor performance recovery after 2-min resting period.

In the baseline condition, the finger motor sequence mainly activated left M1 and bilateral primary somatosensory cortex (S1), premotor cortex (PMC) and cerebellum. After 5 min of motor sequence repetition, both spatial and temporal accuracy were deteriorated and the activity in left M1 was not statistically significant while in S1 and cerebellum became unilateral. Also, bilateral PMC and left supplementary motor areas were significantly activated. Then, after 2 min of resting condition a complete recovery of motor performance was observed. In this condition brain activity in the sensorimotor areas became unilateral (left) and there was a significant activation in subcortical structures (caudate nucleus, putamen, substantia nigra and thalamus), involving also the limbic system (amygdala). All these findings demonstrate that not only motor but also prefrontal and limbic basal ganglia circuits run parallel in restoring motor performance.