Friday, September 6, 2013

David Carlson: September 11th

Title: Real-Time Inference for a Gamma Process Model of Neural Spiking

Abstract: With simultaneous measurements from ever increasing populations of neurons, there is a growing need for sophisticated tools to recover signals from individual neurons. In electrophysiology experiments, this classically proceeds in a two-step process: (i) threshold the waveforms to detect putative spikes and (ii) cluster the waveforms into single units (neurons). We extend previous Bayesian nonparametric models of neural spiking to jointly detect and cluster neurons using a Gamma process model.  We develop an online approximate inference scheme enabling real-time analysis, with performance exceeding the previous state-of-the-art. Via exploratory data analysis we find several features of our model collectively contribute to our improved performance including: (i) accounting for colored noise, (ii) detecting overlapping spikes, (iii) tracking waveform dynamics, and (iv) using multiple channels.

In my talk, I will give a brief overview of the Bayesian nonparametric structures that have been used in the spike-sorting problem.  From there, I will give details on how we've taken the spike sorting model and integrated it with a Poisson process to improve the noisy detection problem, and give details on learning the model using real-time online methods.  Additionally, I will discuss extensions to evolving waveform dynamics and multiple channels, and present results from a tetrode as well as from novel 3-channel and 8-channel multi-electrode arrays where action potentials may appear on some but not all of the channels.

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