Estudo da dinâmica de disparos neuronais

Abstract

The human brain displays a wide variety of firing patterns, from synchronized oscillations during sleep or the learning process to asynchronous dynamic behaviour during physical activity. However, physiological activity can coexist with higly synchronous activities that can promote neurological disorders. In this work, we use the Hodgkin-Huxley model to simulate the potential of one or more neurons to study the possible dynamic behaviours under the effect of slow potassium and calcium ions flux. In our first approach, we conclude that, in one neuron, the slow potassium conductance can promote an adaptation in the firing rate of the membrane potential. However, the high-threshold calcium and the low-threshold calcium have no effect on the firing rate. On the other hand, when we analyze the coefficient of variation, we observe how certain combinations of slow potassium and calcium ion values can promote a transition in the neuron dynamics, from asynchronous firing patterns to synchronous burst activities. Subsequently, we evaluated the behavior of a neuronal network composed of a thousand neurons. Through the Kuramoto order parameter, we studied how the coupling intensity can influence directly the neuronal network dynamic behavior, promoting a transition between firing asynchronous activities to synchronous burst. Lastly, we studied the role of slow potassium ion in the dynamic behavior transition of the neuronal network. We show that the presence of slow potassium conductance in the neuronal network, along with the variation in the value of couple intensity, promotes a bistable regime in some regions of the network. In that, asynchronous firing dynamics coexist with synchronous burst activities. Our results extend our understanding of the intricate ionic interactions present in a neuronal network. Furthermore, it can establish a direct connection with neurobiology, providing potential experimental interventions that can be tested empirically.