  Rhythmic activity in the gamma band (30-100Hz) has been observed in numerous
animal species ranging from insects to humans, and in relation to a wide range
of cognitive tasks. Various experimental and theoretical studies have
investigated this rhythmic activity. The theoretical efforts have mainly been
focused on the neuronal dynamics, under the assumption that network
connectivity satisfies certain fine-tuning conditions required to generate
gamma oscillations. However, it remains unclear how this fine tuning is
achieved.
  Here we investigated the hypothesis that spike timing dependent plasticity
(STDP) can provide the underlying mechanism for tuning synaptic connectivity to
generate rhythmic activity in the gamma band. We addressed this question in a
modeling study. We examined STDP dynamics in the framework of a network of
excitatory and inhibitory neuronal populations that has been suggested to
underlie the generation of gamma. Mean field Fokker Planck equations for the
synaptic weights dynamics are derived in the limit of slow learning. We drew on
this approximation to determine which types of STDP rules drive the system to
exhibit gamma oscillations, and demonstrate how the parameters that
characterize the plasticity rule govern the rhythmic activity. Finally, we
propose a novel mechanism that can ensure the robustness of self-developing
processes, in general and for rhythmogenesis in particular.
