Intro | Auditory Cortex | Cochlear Nucleus | Inferior Colliculus | Medial Geniculate | Superior Olive
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Auditory signals from each ear synapse first in the Cochlear Nucleus on the same side of the brain. The cochlear nucleus is located in the medulla. There are actually two cochlear nuclei on each side of the medulla, the ventral and dorsal nuclei.
Considerable detail is known about the auditory pathway (Parent, 1996). Each auditory nerve fiber splits to synapse in both the dorsal and ventral cochlear nuclei. Each of these cochlear nuclei is organized in subdivisions that are identified by morphologically distinct cells with specific frequency response characteristics. The dorsal, caudal, and medial subdivisions of both the dorsal and ventral cochlear nuclei respond to high frequency sound waves, whereas the ventral, rostral, and lateral subdivisions of each cochlear nucleus respond to low frequency sound waves. The majority of cells in the cochlear nuclei respond to a narrow range of sound frequencies. The exception to this occurs in the posteroventral portion of the cochlear nuclei by a group of neurons called octopus-cells, which respond to a wide range of sound frequencies.
Parent, A. (1996). Carpenter's human neuroanatomy (9th ed.). London: Williams & Wilkins.