One Brookings Drive, St. Louis, MO 63130 Peripheral auditory neurons are tuned to single frequencies of sound. The mechanisms to create the response properties of these neurons have been considered to be solely caused by divergent and convergent projections of neurons in the ascending auditory system. The corticofugal function consists of at least the following subfunctions. Egocentric selection for short-term modulation of auditory signal processing according to auditory experience . Egocentric selection, based on focused positive feedback associated with widespread lateral inhibition, is mediated by the cortical neural net working together with the corticofugal system.
Reorganization is based on egocentric selection working together with nonauditory systems.
Gain control based on overall excitatory, facilitatory, or inhibitory corticofugal modulation . Egocentric selection can be viewed as selective gain control. Filter properties of neurons in the frequency, amplitude, time, and spatial domains can be sharpened by the corticofugal system. Sharpening of tuning is one of the functions of egocentric selection.