Axon collaterals of spinocerebellar fibers terminate in the parabrachial nucleus of the rat.

When horseradish peroxidase (HRP) or wheat germ agglutinin conjugated with HRP was injected into the anterior cerebellar vermis or the spinal cord segments in the rat, terminal labeling was seen in the small round area within the dorsal part of the middle one-third of the parabrachial nucleus (PB). When the tracer was injected into the round PB area, many neuronal cell bodies were labeled in the spinal cord segments, but none in the cerebellum. Thus, the terminal labeling in the round PB area was assumed to be that of axon collaterals of spinocerebellar fibers.