Parameters for a model of an oscillating neuronal network in the cochlear nucleus defined by genetic algorithms.

Chopper neurons in the cochlear nucleus are characterized by intrinsic oscillations with short average interspike intervals (ISIs) and relative level independence of their response (Pfeiffer, Exp Brain Res 1:220-235, 1966; Blackburn and Sachs, J Neurophysiol 62:1303-1329, 1989), properties which are unattained by models of single chopper neurons (e.g., Rothman and Manis, J Neurophysiol 89:3070-3082, 2003a).

A map of periodicity orthogonal to frequency representation in the cat auditory cortex.

Harmonic sounds, such as voiced speech sounds and many animal communication signals, are characterized by a pitch related to the periodicity of their envelopes. While frequency information is extracted by mechanical filtering of the cochlea, periodicity information is analyzed by temporal filter mechanisms in the brainstem. In the mammalian auditory midbrain envelope periodicity is represented in maps orthogonal to the representation of sound frequency.

A simulation of chopper neurons in the cochlear nucleus with wideband input from onset neurons.

The unique temporal and spectral properties of chopper neurons in the cochlear nucleus cannot be fully explained by current popular models. A new model of sustained chopper neurons was therefore suggested based on the assumption that chopper neurons receive input both from onset neurons and the auditory nerve (Bahmer and Langner in Biol Cybern 95:4, 2006). As a result of the interaction of broadband input from onset neurons and narrowband input from the auditory nerve, the chopper neurons in our model are characterized by a remarkable combination of sharp frequency tuning to pure tones and faithful periodicity coding.

Scopolamine attenuates tinnitus-related plasticity in the auditory cortex.

High doses of salicylate induce a temporary hearing deficit and a temporary subjective tinnitus in humans and animals. In animals, salicylate suppresses activity in the ascending auditory system but generates activity and plasticity in the auditory cortex and central amygdala. In addition to changes in the auditory system evoked by hearing impairment, enhanced stress may be crucial for the salicylate-induced alterations in the auditory cortex.

Oscillating neurons in the cochlear nucleus: II. Simulation results.

A computer model of sustained chopper neurons in the ventral cochlear nucleus is presented and investigated. In the companion paper, the underlying neurophysiological and neuroanatomical data are demonstrated. To explain the preference of chopper neurons for oscillations with periods which are multiples of a 0.