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Wednesday, June 21 • 11:28am - 11:40am
Continuous-Time Point-Process Factor Analysis in Julia

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Neurons throughout the brain, and particularly in the cerebral cortex, represent many quantities of interest using population codes. Latent variable models of neural population activity may be seen as attempting to identify the value, time-evolution and encoding of such internal variables from neural data alone. They do so by seeking a small set of underlying processes that can account for the coordinated activity of the population.introduce a novel estimation method [1] for latent factor models for point processes that operates on continuous spike times. Our method is based on score matching for point process regressions [2] adapted to population recordings with latent processes formed by mixing basis functions.basis functions are represented as either Fourier modes, or functions living in a Reproducing Kernel Hilbert Space, parametrised using MLKernels. The method requires the kernel matrix as well as the first and second derivatives thereof, which we can compute efficiently via the Calculus package, making use of anonymous functions. Parameter estimation is then closed form and thus lightning fast up to normalisation, but afterwards we need to estimate the total intensity in the observation period. The approximation of the time integral relies on Cubature.jl.to its speed, this method enables neuroscientists to visualise latent processes in real time during experimental recordings and immediate compare them to their expectations, thus quickening the Planning-Design-Analysis loop by a large margin.1. https://github.com/gbohner/PoissonProcessEstimation.jl2. Sahani, M; Bohner, G and Meyer A, 2016 - Score-matching estimators for continuous-time point-process regression models. MLSP2016


Gergo Bohner

Gatsby Computational Neuroscience Unit, UCL
Gergo focused on math and physics in high school, but completed an engineering degree in Molecular Bionics as an undergrad in his home city, Budapest. After being the image processing guy in a cancer research lab in London as well as learning about AI in Leuven, Belgium, Gergo settled... Read More →

Wednesday June 21, 2017 11:28am - 11:40am PDT
West Pauley Pauley Ballroom, Berkeley, CA