Thermal effects and ephaptic entrainment in Hodgkin-Huxley model

The brain is understood as an intricate biological system composed of multiple elements. It is susceptible to diverse physical and chemical influences, including temperature. The literature widely explores the conditions that affect synapses in the context of cellular communications. However, the understanding of how brain global physical conditions can modulate ephaptic communication remains limited, because the still poorly understood nature of ephapticity. This study proposes an adaptation of the Hodgkin and Huxley model, HH-E, to investigate the effects of ephaptic entrainment in response to thermal changes. The analysis focus on two distinct neuronal regimes: subthreshold and suprathreshold. In the subthreshold regime, the circular statistic is used to show the phase differences dependence on temperature. In the suprathreshold regime, the Population Vector and the Inter-Spike Interval are used to estimate phase preferences and changes in the spiking pattern. Temperature affects positively the HH-E model spiking frequency. At high temperatures the HH-E model collapses and no more spiking are observed. Moreover, temperature difference improves the anti-phase between spikes and the ephaptic external signal. In the suprathreshold regime, the ephaptic entrainment is influenced by temperature, specially at low frequencies. Finally, this study reveals the susceptibility of ephaptic entrainment to temperature variations in both subthreshold and suprathreshold regimes and discusses the importance of ephaptic communication in pathological contexts in which temperature play an important role in neural physiology, such as inflammatory processes, fever and epileptic seizures.