Auditory Pathways: the "primary auditory cortex" receives auditory “projections” from the “lateral geniculate nucleus” (inside the “thalamus”). (Patestas, 313)
Experiments (with rats by Joseph LeDoux) showed that there is an acoustic pathway that actually by-passes the auditory cortex. If you cut the “acoustic nerve” there will be no “fear” response. (However), if you remove the “auditory cortex” itself, it doesn’t have any effect on the fear response. In other words, the rat doesn’t have to be aware of the sound to feel fear. (CampbellVA, 101) Disorders of hearing or auditory “perception” due to “pathological” processes of the auditory pathways in the “central nervous system” include central hearing loss and auditory perceptual disorders. (MeSH)
Arcuate Fasciculus: Carl Wernicke demonstrated that comprehension and expression (of language) are not only processed separately, but that they are connected to each other by this pathway. The information from hearing is sent from our ears to the “auditory cortex.” Information we obtain from reading is transmitted from our eyes to the “visual cortex.” Information from these two cortical areas then converges in Wernicke’s area, which translates it into a neural code for understanding language. Only then does the information proceed to Broca’s area (via the arcuate fasciculus), enabling us to express ourselves. (Kandel4, 11-12)
Auditory Nerve: part of the 8th cranial nerve. The cochlear nerve fibers project peripherally to “cochlea hair cells” and centrally to the “auditory nucleus” of the “brain stem.” Mediates the sense of hearing. (MeSH) The major conduit connecting the "inner ear" to the brain stem. Once in the brain stem, the auditory nerve hooks up with the “auditory nucleus.” (Ramachandran, 36) Also referred to as ‘acoustic nerve’ and ‘cochlear nerve.’
Auditory Nucleus: located at the brainstem, this sensory organ receives auditory signals from the auditory nerve fibers. (NCIt) Receives the central input from the cochlear nerve. The cochlear nucleus is located (in the brain stem) and is functionally divided into dorsal and ventral parts. It performs the first stage of central auditory processing, and projects (directly or indirectly) to higher auditory areas. (MeSH) Damage to the auditory nerve prevents the auditory nucleus from getting input from one ear. When this happens, “axons” from the occulomotor nerve nucleus ‘invade’ the auditory nucleus so that every time the person’s brain sends a command to move the eyes, that command is sent inadvertently to the auditory nerve nucleus and translated in the ringing sound associated with “gaze tinnitus.” (Ramachandran, 38) Also referred to as ‘cochlear nucleus.’
Central Auditory Pathway: originates in the ‘cochlear nuclei,’ forms multiple “synapses” as it ascends the “brainstem,” (connects) in the “diencephalon,” and terminates in the "auditory cortex." (Fisch, 424)