This summer, I worked on a project exploring neurons in the olfactory pathway called mitral cells and a phenomenon called stochastic synchrony. Mitral cells are neurons in the olfactory bulb that transmit an olfactory signal from olfactory sensory neurons to the cortex. Researchers have observed synchronized gamma frequency oscillations in the firing of mitral cells, but it is still unclear exactly why and how these oscillations are produced. One prominent theory for how these oscillations arise is the mechanism of stochastic synchrony, which predicts that these synchronous oscillations are caused by correlated inhibitory inputs to the mitral cells. I studied this mechanism by computationally modeling mitral cells in MATLAB using Eugene Izhikevich’s Simple Model of Spiking Neurons.
First, I recreated the results produced by past researchers on stochastic synchrony, showing that correlated inhibitory inputs to simulated mitral cells can cause synchrony among all the mitral cells, as well as oscillations in the gamma frequency range in their firing. This synchrony and these oscillations were also shown to increase as the level of correlation increased, and this phenomenon was also observed with correlated excitatory current. Additionally, I modeled a network of mitral cells, granule cells (which provide inhibitory input to the mitral cells), odor input, and cortical feedback. Using this network, I tried to recreate the synchronous oscillations in the mitral cells with correlated inhibitory input from the granule cells. I also explored the effect of adding cortical feedback, which has been linked in the past to beta frequency oscillations and olfactory learning.