MAPPING OF THE COCHLEAR NUCLEUS SUBREGIONS IN THE RAT WITH NEURONAL FOS PROTEIN-INDUCED BY ACOUSTIC STIMULATION WITH LOW TONES

To explore the mode of appearance of Fos, a gene product of proto-oncogene c-fos, in the cochlear nucleus, a pure tone was given to rats and Fos was detected by immunohistochemistry. Following low-tone stimuli applied with moderate ranges of sound intensity, neurons with Fos-label occurred band-like in the ventral subregions of the dorsal cochlear nucleus. Organization of low-to-high tones in the ventral-to-dorsal orientation became visible at the caudal level. Several other subnuclei consistently exhibited Fos with no topographic pattern. Neurons interspersed in the adjoining vestibulocochlear nerve were also found to elicit Fos. Low-tone stimuli with very high sound intensity led to a rather widespread distribution of Fos, making the tone-specific distribution less visible.