Structural brain plasticity modified by action observation training in healthy subjects

Abstract

Methods: Using a 3T scanner, fMRI scans during the observation (O) of a video showing a task performed by another person and the simultaneous execution and observation (EO) of the same task were obtained from three groups of healthy subjects. Forty-five subjects were randomized into three groups of 15 subjects. Each group had to perform one of the following task: a simple motor task (SM) (flexionextension of the last four fingers of the right hand), a complex motor task (CM) (flexion-extension alternated to abductionadduction of the last four fingers of the right hand) and a transitive motor task (TM) (use of an object with the right hand). Manual dexterity was assessed using the 9-hole peg test (9HPT) and maximum finger tapping frequency (FT). fMRI data were analyzed using SPM8. Significant differences were consideredwith p< 0.05. The studywas approved by the local Ethical Committee and an informed consent was signed by each subject. Results: Demographic and manual dexterity data did not differ between groups. DuringO task, the SM and TMgroups had an increased activation of the bilateral inferior frontal gyrus compared toCM.DuringOandOE tasks, theTMgroup experienced a higher activation of the left inferior parietal lobe compared to SM and CM; whereas the CM group had higher activation of the superior parietal gyrus than the TM and SM ones. Conclusion(s): Both the modalities of administration (observation vs observation and execution) and the type of task (simple, complex or transitive) modulate MNS recruitment. Implications: In recent years, action observation (AO) namely the imitation ofmovement after their observation, has become a valuable tool for relearning motor tasks in rehabilitation approaches. The best strategy for AO administration is still an open question. It is reasonable to speculate that AO characteristics should also depend from the location of central nervous system (CNS) lesions. This study provides some novel pieces of information for planning AO strategies in subjects with CNS lesions.