Projections from the auditory cortex to the pontine nuclei in the rabbit.

The pontine projection from the auditory cortex was studied in 24 New Zealand albino rabbits using the method of anterograde transport of HRP-WGA. Microinjections of HRP-WGA (0.03-0.1 microliter) were made in the auditory cortex, which was located by electrophysiological criteria. The auditory cortex was shown to project ipsilaterally to ventral and lateral regions in the caudal pontine nuclei, and to the dorsolateral pontine nuclei in more rostral sections. Labeled terminals were also occasionally seen in the caudal medial pontine nuclei. These results suggest that the auditory cortex can modulate cerebellar input from caudal regions of the pontine nuclei, which project to cerebellar regions shown to be important for classical conditioning.