Emergence and fragmentation of the alpha-band driven by neuronal network dynamics

Abstract

Rhythmic neuronal network activity underlies brain oscillations. To investigate how connected neuronal networks contribute to the emergence of the -band and the regulation of Up and Down states, we study a model based on synaptic short-term depression-facilitation with afterhyperpolarization (AHP). We found that the -band is generated by the network behavior near the attractor of the Up-state. Coupling inhibitory and excitatory networks by reciprocal connections leads to the emergence of a stable -band during the Up states, as reflected in the spectrogram. To better characterize the emergence and stability of thalamocortical oscillations containing and{delta} rhythms during anesthesia, we model the interaction of two excitatory with one inhibitory networks, showing that this minimal network topology leads to a persistent -band in the neuronal voltage characterized by dominant Up over Down states. Finally, we show that the emergence of the -band appears when external inputs are suppressed, while the fragmentation occurs at small synaptic noise or with increasing inhibitory inputs. To conclude, interaction between excitatory neuronal networks with and without AHP seems to be a general principle underlying changes in network oscillations that could apply to other rhythms. Author summaryBrain oscillations recorded from electroencephalograms characterize behaviors such as sleep, wakefulness, brain evoked responses, coma or anesthesia. The underlying rhythms for these oscillations are associated at a neuronal population level to fluctuations of the membrane potential between Up (depolarized) and Down (hyperpolarized) states. During anesthesia with propofol, a dominant alpha-band (8-12Hz) can emerge or disappear, but the underlying mechanisms remain unclear. Using modeling, we report that the alpha-band appears during Up states in neuronal populations driven by short-term synaptic plasticity and noise. Moreover, we show that three connected networks representing the thalamocortical loop reproduce the dynamics of the alpha-band, which emerges following the arrest of excitatory stimulations, but can disappear by increasing inhibitory inputs. To conclude, short-term plasticity in well connected neuronal networks can explain the emergence and fragmentation of the alpha-band.