Roles played by depressing synapses in neural circuits
Joanna Jędrzejewska-Szmek (University of Warsaw Faculty of Physics), Jarosław Żygierewicz (University of Warsaw Faculty of Physics)
by [1,3]. Both models generated oscillatory signals as predicted by [2,3].
In case of both models a regime exists with high frequency oscillations (higher than 80 Hz) and high amplitude of oscillations corresponding to 'high-gamma' characteristics . The model with depressing positive feedback showed three regimes: 1) oscillations in the theta band almost independent of external input of the excitatory population, 2) high-frequency oscillations with an envelope frequency in the theta band. In the third regime we observed oscillations in theta and 'high-gamma band'. An increase of the external input can abruptly change the oscillation frequency from the theta band to 'high-gamma'. Excitatory population firing rate is shown in the Figure below. One can see, that generated activity is similar to the theta/gamma oscillations  linked to short-term memory [5,6].
Short-term synaptic depression plays important role in generation of not only slow
oscillations activity  and theta waves, but also higher frequency phenomena such as 'high-gamma'. It
might also serve as a basis for coupling between the high- and low-frequency bands of
ongoing electrical activity in the human brain [5,6,7].
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