The pontine projection from the inferior colliculus in the cat. An experimental anatomical study

The present study was carried out in order to clarify the organization of the pontine projection from the inferior colliculus in the cat with the methods of Nauta27 and Fink and Heimer16 following lesions of different sizes and locations in the inferior colliculus. The inferior colliculus projects exclusively to the anterior two-thirds of the ipsilateral dorsolateral pontine nucleus. The majority of fibers originates from cells in the central nucleus and a small amount from cells in the external and the pericentral nuclei as well. Areas of the present projection largely overlap with areas of projection from the auditory cortex, and also fairly well with those from the superior colliculus. Possible pathways of the acoustic inputs to the cerebellum involving the pontine nuclei are discussed based upon the current findings, as well as upon those obtained by preliminary experimental studies of anterograde and retrograde axonal flow.