Modulation of afferent inflow during the control of balancing tasks using the lower limbs.

This study investigated the control of sensory inputs during the performance of an inverted-pendulum balancing task. Experiments were conducted to examine modulation of proprioceptive inputs during balance tasks of varying difficulty. It was hypothesized that proprioceptive inputs to both spinal and cortical levels would be facilitated during a challenged balance task. In contrast, during challenged balance control, results revealed task-specific facilitation of sensory inputs to the cortex and inhibition of the spinal reflex pathway. Observations of increased transmission of proprioceptive inputs to the cortex and decreased transmission at the spinal level suggest that the cortex plays an important role in challenged balance, whereas the role for the spinal stretch reflex appears to be less important.