TASK-DEPENDENT MODULATION OF GAIT CONTROL IN PARKINSON'S DISEASE

Constraining gait rhythm with a metronome has been shown to influence gait pattern in many different ways. While such a rhythmic cueing can improve several parameters in some clinical populations such as patients suffering from Parkinson’s disease (PD), they do deteriorate the long-range autocorrelations (LRA) naturally present in series of stride durations. This change in LRA has been interpreted in the framework of optimal control as a modulation of gait regulation through a change in motor cost. Cueing paradigms therefore require flexible adjustments when walking conditions change. As the basal ganglia have been associated with the representation of motor cost, they may also contribute to such adjustments.
To test this hypothesis, 27 PD patients with mild to moderate symptoms (clinical score: H&Y = [1-3]) and 26 healthy controls individuals were asked to walk overground during two 15-minutes conditions. A metronome was activated either during the first half or during the second half of the session in order to test both transitions. We assessed the modulation of gait regulation through changes in LRA, using a sliding window to characterize its temporal evolution. PD participants exhibited overall modulation comparable to healthy controls as they exhibited similar changes in LRA following the addition or removal of the metronome cueing. However, the temporal adaptation differed between groups, with patients showing a slower adjustment to the introduction of rhythmic cues. Together, these results support a role of the basal ganglia in gait regulation influencing modulation timing, without altering modulation amplitude.