Influence of temperature on neuronal excitability in cochlear nucleus

Abstract

The influence of temperature on neuronal excitability is studied by numerical simulations on the spiking threshold characteristics of bushy cells in cochlear nucleus periodically stimulated by synaptic currents. The results reveal that there is a cut-off frequency for the spiking of bushy cell in a specific temperature environment, corresponding to the existence of a critical temperature for the neuron to respond with real spikes to the synaptic stimulus of a given frequency, due to the finiteness of spike width. An optimal temperature range for neuronal spiking is also found for a specific stimulus frequency, and the temperature range span decreases with increasing stimulus frequency. These findings imply that there is a physiological temperature range which is beneficial for the information processing in auditory system. PACS numbers: 87. 19. Dd, 87. 10. +e, 87. 17. Aa, 87. 19. La Electric excitability has been attracting much attention for decades, for it is the basis of information processing and is essential to coding in neural systems. The excitability of a neuron originates from integrated effect of the kinetics [1], as well as the spatial distribution [2], of ion channels on the cellular membrane in proper environment, and determines the functional properties when responding to external stimulus, such as the frequency sensitivity [3,4] or selectivity [5], interaural time difference (ITD) sensitivity in auditory system [6], etc. Excitability and response properties of a neuron may vary in different environmental conditions of, say, temperature and pH values [7]. Recently, the influence of temperature on the excitability of rat suprachiasmatic nucleus neurons has been investigated experimentally, and the results reveal that there is a temperature-sensitive range for the neuronal activities; this may provide cues to the circadian synchronized rhythmicity [8,9]. Biophysically, temperature may influence the functioning of a neuron through the temperature dependence of various ion channel conductances and time constants of channel activation/inactivation variables [10]; hence changing temperature alters the basic properties of excitable neuron, such as the membrane potential, the input resistance, the shape and amplitude of action potentials, and the propagation of spikes [11,12,13,14]. Up to date, however, there has been little theoretical investigations of the influence of temperature on neuronal excitability in literature.Neuronal excitability can be described by the firing properties, like the spiking threshold of the neuron responding to periodic stimulus [5]. Characteristics of the spiking threshold of excitable neurons have been discussed in several studies [3,5,15,16,17], where the stimuli applied are mostly sinusoidal. More realistically, in fact, the stimulus to a post-synaptic neuron is often described by a current with alpha-function channel conductance [18], which is used in the present study. Comparable with Ref. [5], this work focuses on the effect of temperature on the spiking threshold of a...

Thermal impact on spiking properties in Hodgkin-Huxley neuron with synaptic stimulus

“…can be further generalized to other nervous systems, such as the cochlear nucleus neuron in auditory system [32]. Presumably, this subcellular mechanism of thermal impacts on the neuronal spiking via ion channel kinetic behaviours can serve as the base for the psychophysical evidence that various animals live optimally in a specific range of environmental temperature.…”