Hindlimb muscle activity during unrestrained walking in cats with lesions of the lateral funiculi.

In freely moving intact cats and cats with bilateral lesions of the lateral funiculi the foot contact signals and the activity of selected muscles operating at the ankle and knee joints were analysed during walking at moderate speed (0.4-1.0 m/s). No essential changes in the activity of the muscles gastrocnemius lateralis (GL), semitendinosus (ST) and vastus lateralis (VL) were found in operated animals. The tibialis anterior (TA) muscle activity had a shorter duration than the swing phase in operated animals and showed an impaired coactivation with gastrocnemius lateralis (GL) muscle at the end of the swing phase. Pilot experiments indicated that these deficits may be partly compensated for by peroneal nerve electrostimulation. Analysis of regression lines relating the swing duration to the step duration, determined from EMG records, confirmed our previous results, based on foot contact signals (Górska et al. 1993), showing that in cats with lateral funicular lesions the swing duration varies much more with the step duration than in intact animals.