Channel noise induced stochastic facilitation in an auditory brainstem neuron model

摘要

Neuronal membrane potentials fluctuate stochastically due to conductancechanges caused by random transitions between the open and close states of ionchannels. Although it has previously been shown that channel noise cannontrivially affect neuronal dynamics, it is unknown whether ion-channel noiseis strong enough to act as a noise source for hypothesised noise-enhancedinformation processing in real neuronal systems, i.e. 'stochasticfacilitation.' Here, we demonstrate that biophysical models of channel noisecan give rise to two kinds of recently discovered stochastic facilitationeffects in a Hodgkin-Huxley-like model of auditory brainstem neurons. Thefirst, known as slope-based stochastic resonance (SBSR), enables phasic neuronsto emit action potentials that can encode the slope of inputs that vary slowlyrelative to key time-constants in the model. The second, known as inversestochastic resonance (ISR), occurs in tonically firing neurons when smalllevels of noise inhibit tonic firing and replace it with burst-like dynamics.Consistent with previous work, we conclude that channel noise can providesignificant variability in firing dynamics, even for large numbers of channels.Moreover, our results show that possible associated computational benefits mayoccur due to channel noise in neurons of the auditory brainstem. This holdswhether the firing dynamics in the model are phasic (SBSR can occur due tochannel noise) or tonic (ISR can occur due to channel noise).