Neural Generators of Auditory Brainstem Responses studied by the [14C] deoxyglucose Method in Rats

[14C] deoxyglucose was injected into the peritoneal cavity of rats with destructed brainstem, and the auditory stimulation was sustained for 45 minutes. At the end of the stimulation, the brain as a whole was immediately removed and frozen sections of 8μm were made. Autoradiographs were then prepared by exposing the sections to x-ray films. The results of autoradiograms were compared with the changes of ABR induced by the destruction. These results lead to the following conclusions in summary: (1) Waves of P2, P3, P4 and P5 might have their corresponding generators respectively in several parts of the brainstem auditory pathway. (2) The inferior colliculus is not essential for the generation of fast waves. (3) The wave of P5 has its main generator in the afferent nerve fibers which project to the contralateral inferior colliculus. (4) The generators of P4 are distributed between the contralateral superior olivary complex and the vicinity of ventral nucleus of the contralateral lateral lemniscus. (5) The wave of P3 is generated by bilateral auditory pathways in the vicinity of the superior olivary complex. (6) Main generator of P2 is in the ipsilateral cochlear nucleus, however, the medial portion of the 8th nerve and the ipsilateral superior olivary complex might participate to some extent.