Understanding Human Neural Control of Short-term Gait Adaptation to the Split-belt Treadmill

Many studies of split-belt treadmill adaptation have been focused on the biomechanical changes that occur in response to walking on belts at different speeds. This process of adaptation, and the ensuing aftereffects that are present when participants return to typical treadmill walking, have inspired the potential use of the split-belt treadmill as a rehabilitation tool. However, a full systematic review of the current split-belt treadmill literature has not yet been published to consolidate what is known about how the human central nervous system (CNS) controls adaptation to this type of symmetry perturbation. A systematic literature search identified 55 studies that investigated the neural control of human gait adaptation to a split-belt treadmill. Studies of infants and manipulated sensory feedback in healthy adults suggest that the initial gait adjustments to split-belt walking are reliant on proprioceptive feedback to inform central pattern generators to modify lower limb muscle activation patterns appropriately. Simultaneously, this literature suggested that proprioceptive and visual feedback inform supraspinal centres for motor planning and motor output to adapt and store a new and efficient gait pattern to walk on belts at different speeds. However, evidence from participants with brain injury (post-stroke, cerebellar lesions) suggest that injury impedes, but does not completely take away, the ability to adjust and adapt aspects of the gait pattern to split-belts. The model proposed from this review provides the overarching roles of the CNS in the adaptation process, specifically in short-term, and potential sites of focus within the human CNS for future rehabilitation-based work.