Neural Coherence of Homologous Muscle Pairs During Direct EMG Control of Standing Posture in Transtibial Amputees

Abstract

The objective of this preliminary study was to investigate the feasibility of a transtibial amputee to improve interlimb muscle coordination while using direct, continuous control of a powered ankle prosthesis combined with physical therapist guided training, for improved standing postural control. A participant with transtibial amputation received an extended PT-guided training on posture while using the dEMG control of powered ankle with his residual Tibialis Anterior and Lateral Gastrocnemius. We quantified cross-correlation of Center of Pressure excursions and coherence in EMG signals from the bilateral shank muscles. Between-limb coordination was observed as synchronized activation of homologous muscles in the shank. We observed increased coherence in the TA muscle pair after training in 0–5 Hz and 10–20 Hz frequency ranges. These results demonstrate the potential for amputees to closely coordinate residual muscle activations with intact muscles given sufficient training. It is further possible amputees adapt sources of descending neural commands between homologous muscle pairs after guided training. Future study requires more participants to validate these results.