Locomotion is necessary for survival in most animal species.
However, injuries to the appendages mediating locomotion are
common. We assess the recovery of walking in Drosophila
melanogaster following leg amputation. Whereas flies preamputation explore open arenas in a symmetric fashion on average,
foreleg amputation induces a strong turning bias away from the side of
the amputation. However, we find that unbiased walking behavior
returns over time in wild-type flies, while recovery is significantly
impaired in proprioceptive mutants. To identify the biomechanical
basis of this locomotor impairment and recovery, we then examine
individual leg motion (gait) at a fine scale. A minimal mathematical
model that links neurodynamics to body mechanics during walking
shows that redistributing leg forces between the right and left side
enables the observed recovery. Altogether, our study suggests that
proprioceptive input from the intact limbs plays a crucial role in the
behavioral plasticity associated with locomotor recovery after injury.