Abstract
Using optical imaging with voltage-sensitive dye in newborn rat cerebellum-pons-medulla (-spinal cord) block preparations, we recorded respiratory activities in the cerebellum, rostral ventrolateral medulla (RVLM), inferior olive and nucleus parabrachialis (NPB). Cycle triggering with C4 inspiratory activity revealed optical responses distributed in the lateral part of VII-VIII lobules, paraflocculus, lateral end of vermis and also the dorsal respiratory group (DRG) in the dorsal view of the medulla. There are two types of respiratory pathways in the cerebellum related to pulmonary afferent and respiratory rhythm. Vagus nerve stimulation activated the nucleus tractus solitarii (NTS), NPB and also ipsilateral hemisphere of the cerebellum. It is notable that respiratory neuronal activities in the cerebellum are mediated by the inferior olive and NPB. It was confirmed using DiI transport that the inferior olive projects to the paraflocculus and lateral hemisphere around VII-VIII lobule, while it receives input from the neurons below the ambiguus nucleus. The present results indicate that respiratory activities are major sources of both climbing fiber and mossy fiber inputs to the cerebellum in the neonatal stage. These activities may play a role in the activity-dependent formation of cerebellar neuronal circuitry. [J Physiol Sci. 2007;57 Suppl:S215]
