Role of the cerebellum in adaptive control of locomotion

To perform smooth and stable locomotion, animals coordinate not only parts of a limb, but also different limbs. The dynamics of coordination is modified according to changes of external conditions due to obstacles or unexpected perturbation. It is established that the cerebellum is necessary for interlimb coordination and adaptive control of locomotion. The cerebellum receives information through the spinocerebellar pathways about the ongoing activities both in the spinal stepping generator and at the somatosensory receptors during locomotion. This information conveyed by mossy fiber afferents to Purkinje neurons via granule cells and their axons, i.e., parallel fibers. Purkinje neurons transform the mossy fiber input signals to output signals that in turn modulate activities in brainstem decending tract neurons involved in locomotion. On the other hand, Purkinje neurons receive enhanced climbing fiber signals during perturbed locomotion. These climbing fiber signals are expected to induce synaptic plasticity at the parallel fiber-Purkinje neuron synapses. This article will highlight some recent advances into understanding the role of the cerebellar synaptic plasticity for the adaptive control of locomotion