In learning about the auditory sense we see many parallels with other sensory systems. Auditory information must be translated into a neural impulse (in the form of a receptor potential) before we can "hear" anything; visual, olfactory and gustatory stimuli, too, must undergo transduction before our brain can understand it. Auditory information ascends the thalamus via the medial geniculate nucleus; visual information travels through the lateral geniculate nucleus. Audition has its own specific cortical area, called the primary auditory cortex, or A1; the visual system also has its own cortical area, the primary visual cortex or V1. The visual cortex shows a retinotropic organization in which nearby cells in the visual field correspond to nearby cells in the retina; similarly, auditory information is grouped in a tonotropic organization in which neighboring auditory cells (in the auditory nerve, MGN and auditory cortex) correspond to similar frequencies of sound stimuli (in other words, these neurons have similar characteristic frequencies--the sound frequency to which the neuron is most responsive). These are just a few of the similarities between vision and audition. Audition also shares characteristic propterties with the other senses we've studied, olfaction and gustation.
See you next week.