Mechanisms of coincidence detection in the auditory brainstem: Examples

Abstract

The auditory brainstem in mammals contains a neural circuit for sound localization. The exact functioning of this circuit is still under controversy. Two spike generation mechanisms studied previously, excitatory coincidence detection and inhibitory coincidence detection, are studied here regarding the input-output relationship of the spike time densities. We propose that synchronous binary multiplication operation on spikes is the underlying process of these two variants of coincidence detection. A derivation of time to the spike is shown, which enables us to estimate the contribution of the neural circuit in the auditory brainstem to the overall reaction time of sound localization. The brainstem contribution is minute compared to the conduction delays in the mammalian neocortex. Finally, the skewness of the resulting output spike time densities is discussed in both the excitatory and inhibitory cases and the inhibitory case is shown to be close to the normal density with a standard goodness-of-fit test for the normal probability density function.