Abstract
We investigate the emergence of in-phase synchronization in a heterogeneous network of coupled inhibitory interneurons in the presence of spike timing dependent plasticity (STDP). Using a simple network of two mutually coupled interneurons (2-MCI), we first study the effects of STDP on in-phase synchronization. We demonstrate that, with STDP, the 2-MCI network can evolve to either a state of stable 1:1 in-phase synchronization or exhibit multiple regimes of higher order synchronization states. We show that the emergence of synchronization induces a structural asymmetry in the 2-MCI network such that the synapses onto the high frequency firing neurons are potentiated, while those onto the low frequency firing neurons are de-potentiated, resulting in the directed flow of information from low frequency firing neurons to high frequency firing neurons. Finally, we demonstrate that the principal findings from our analysis of the 2-MCI network contribute to the emergence of robust synchronization in the Wang-Buzsaki network (Wang and Buzsáki, 1996) of all-to-all coupled inhibitory interneurons (100-MCI) for a significantly larger range of heterogeneity in the intrinsic firing rate of the neurons in the network. We conclude that STDP of inhibitory synapses provide a viable mechanism for robust neural synchronization.
Highlights
Cortical gamma rhythms (30–80 Hz) are correlated with diverse brain functions such as memory formation (Singer and Gray, 1995), linguistic processing (Pulvermller et al, 1995), and associative learning (Ritz and Sejnowski, 1997; Miltner et al, 1999)
We investigate how the presence of synaptic plasticity can increase the range of firing rate heterogeneity for which mutually-coupled parvalbumin positive interneuronal (MCI) networks can synchronize at gamma frequencies
In-phase synchronization is significantly enhanced for a wide range of 0 ≤ H ≤ 18 when spike timing dependent plasticity (STDP) is enabled
Summary
Cortical gamma rhythms (30–80 Hz) are correlated with diverse brain functions such as memory formation (Singer and Gray, 1995), linguistic processing (Pulvermller et al, 1995), and associative learning (Ritz and Sejnowski, 1997; Miltner et al, 1999). Interneurons play critical roles for gamma rhythm generation in both mechanisms. In ING, interneurons are solely responsible for gamma frequency activity (Bartos et al, 2002). There is evidence that interneurons show phase-locked activity with gamma oscillations (Bartos et al, 2007). Perisomatic inhibition caused by fast-spiking parvalbumin (PV) immunoreactive basket cell interneurons (Lytton and Sejnowski, 1991) have been implicated in the generation of cortical and subcortical gamma oscillations (Bartos et al, 2007)
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