Transient Motivation

Human walking has been studied extensively with the assumption of steady-state gait. However, we rarely walk under steady-state conditions. Acceleration and deceleration, obstacle negotiation, disturbance rejection and turning are all examples of behavior that require modulation of walking speed which is in turn driven by transient changes in muscle activations. A few studies in recent years have explored characteristics of transient walking [1], [2], [3]. It has been suggested that control of speed works through modulation of braking and propulsive impulses and to increase speed subjects change the braking impulse more than the propulsive one [2]. However, none of these studies have measured muscle activations and the conjectures made were formed by looking at the joint moments and ground reaction impulses. In the most recent study from our lab we have shown that the activity of plantarflexors are modulated to change both the braking and the propulsive impulses (details at www). Visual perturbations were used in these experiments to elicit transient responses in muscles. It is not clear whether mechanical perturbations will result in the same changes during transient …show more content…
We hypothesize that both braking and propulsive components are significantly modulated in response to surface perturbations. The contribution of changes in each component to the total changes in speed is subject to investigation.
Aim #2: To compare and contrast transient responses to mechanical perturbations to those observed in response to visual perturbations and compare both of these transient changes to transient changes during acceleration and deceleration in absence of perturbations (from [] and []). We expect to observe some similarities between different types of transient changes in activations.
Methods