Basal ganglia are active during motor performance recovery after a demanding motor task

Motor performance recovery after a demanding finger motor task does not follow the excitability dynamics of primary motor cortex (M1), which remains depressed also when performance is restored. Thus, other neural circuits are supposed to cope with central fatigue, re-establishing adequate motor performance levels. A hint that the basal ganglia (BG) can be involved in this process is provided by studies showing an association of central fatigue with the BG. To investigate this possibility, we conducted an fMRI study with simultaneous motor performance recording in 20 healthy volunteers at different stages of a demanding finger motor task: baseline, central fatigue induced by 5-min sequence repetition, performance recovery after a short rest period. When motor performance was recovered, we observed a significant activation with respect to baseline in subcortical structures belonging to different BG circuits (putamen and globus pallidus), involving the limbic system functionally interacting with the BC (amygdala). Then, to assess whether the BC activation was exclusively related to the fatigue and recovery processes or to increasing automatism in motor performance, a control fMRI experiment based on a shorter motor task duration was carried out on 14 healthy subjects. In this case, the task repetition did not induce decreased performance, and no significant effect on the BOLD signal change was found in BC regions of interest with respect to baseline. All these findings suggest that motor and non-motor BC circuits run parallel and converge in a common motor path to successfully compensate motor performance deterioration in a central fatigue condition. (C) 2012 Elsevier Inc. All rights reserved.