The cortical modulation from the external cues during gait observation and imagination.

The cortical involvement of gait observation and imagination under the modulation of external cues was studied in human using fMRI. Fourteen healthy volunteers were scanned using visual stimuli, which showed an actor walking in different background. The defined relevant cue was a background of evenly spaced stripes orthogonal to the walking direction, which was rhythmic presented as the actor proceeded. The irrelevant cue was two parallel lines within which the actor was confined. When viewing the relevant cue, the subject showed activation, noticeably in dorsal premotor areas, posterior parietal lobes, bilateral parahippocampal lobes, and visual related areas. The relevant external cue leads to the modulation of cortical activation related to gait, which could initialize the processing of the input information and lead to a different motor strategy from the native automatic gait. The understanding of the cortical involvement of gait under different cues might lead to a new clinical impact on the therapeutic intervention of patients with Parkinson's disease.