Padrões de disparos em redes neuronais

Abstract

Inthisthesis,itwasinvestigatedtheinfluenceoftheexcitatoryandinhibitorychemicalsynaptic conductances to obtain synchronized activity in a neuronal network randomly connected. To describe each neuronal dynamics of the network it was considered the adaptive exponential integrate-and-fire model. Unconnected neurons exhibit spike activity with slightly different subthreshold adaptation intensities. When the neurons are randomly connected forming a network,wenoticedthattheincreaseofexcitatorysynapticconductancesfavorsspikeandburst synchronization while inhibitory ones contributed to the appearance of desynchronized spikes. Thus, changes the intensities of chemical synaptic conductances can generate synchronization and firing pattern transitions. A interesting behavior found in this transition is the bistable regime. In this region, depending on the initial conditions and received external stimuli, the neuronal network can show activity of desynchronized spikes or synchronized bursts. This bistable regime is recurrently related to epilepsy, once the epilepsy patient has both normal and seizures states. In bistable regime, since the neuronal activity is in a pattern of activity, this dynamics remains unchanged over time unless an external stimulus is applied. Thus, the firing pattern on the bistable regime can be modified applying external square current pulses, being a propitious strategy to control epilepsy seizures in patient resistant to pharmacological treatments.