Restoring plantar sensation reduces cognitive cost of dual-task walking after lower limb loss

Abstract Walking in individuals with lower limb loss demands sustained elevated cognitive effort, partly due to the lack of direct sensory feedback from the foot. This feedback plays a critical role in the automatic control of gait. We tested whether restoring somatosensory feedback from the missing foot reduces the cognitive demand of walking. Three participants with unilateral limb loss used a sensory neuroprosthesis (SNP) that provided real-time plantar sensation through electrical stimulation of the remaining peripheral nerves utilizing implanted nerve cuffs. They and two able-bodied controls walked on a self-paced treadmill while performing the Color–Word Matching Stroop (CWMS) test at three difficulty levels. The task was run with and without a response time limit to vary cognitive demand. Reaction time and accuracy were stable and unaffected by the SNP, whereas gait speed showed dual-task interference. Notably, with SNP active, gait speed shifted toward faster walking under the time-limited task, and step length increased, particularly on the prosthetic side. Participants differed in whether they sped up or slowed with task difficulty, consistent with each having a limited range of speeds at which gait is most automatic. The uniform upward shift with the SNP suggests that restored plantar sensation raises that range and shifts the walking from executive to automatic gait control at faster speeds. This reallocation of cognitive resources could facilitate faster, more automatic walking under cognitive load, resulting in safer mobility in daily life.