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Bayesian inference for low rank spatiotemporal neural receptive fields
Mijung Park · Jonathan W Pillow

Thu Dec 05 07:00 PM -- 11:59 PM (PST) @ Harrah's Special Events Center, 2nd Floor

The receptive field (RF) of a sensory neuron describes how the neuron integrates sensory stimuli over time and space. In typical experiments with naturalistic or flickering spatiotemporal stimuli, RFs are very high-dimensional, due to the large number of coefficients needed to specify an integration profile across time and space. Estimating these coefficients from small amounts of data poses a variety of challenging statistical and computational problems. Here we address these challenges by developing Bayesian reduced rank regression methods for RF estimation. This corresponds to modeling the RF as a sum of several space-time separable (i.e., rank-1) filters, which proves accurate even for neurons with strongly oriented space-time RFs. This approach substantially reduces the number of parameters needed to specify the RF, from 1K-100K down to mere 100s in the examples we consider, and confers substantial benefits in statistical power and computational efficiency. In particular, we introduce a novel prior over low-rank RFs using the restriction of a matrix normal prior to the manifold of low-rank matrices. We then use a "localized'' prior over row and column covariances to obtain sparse, smooth, localized estimates of the spatial and temporal RF components. We develop two methods for inference in the resulting hierarchical model: (1) a fully Bayesian method using blocked-Gibbs sampling; and (2) a fast, approximate method that employs alternating coordinate ascent of the conditional marginal likelihood. We develop these methods under Gaussian and Poisson noise models, and show that low-rank estimates substantially outperform full rank estimates in accuracy and speed using neural data from retina and V1.

Author Information

Mijung Park (University of Texas)
Jonathan W Pillow (UT Austin)

Jonathan Pillow is an assistant professor in Psychology and Neurobiology at the University of Texas at Austin. He graduated from the University of Arizona in 1997 with a degree in mathematics and philosophy, and was a U.S. Fulbright fellow in Morocco in 1998. He received his Ph.D. in neuroscience from NYU in 2005, and was a Royal Society postdoctoral reserach fellow at the Gatsby Computational Neuroscience Unit, UCL from 2005 to 2008. His recent work involves statistical methods for understanding the neural code in single neurons and neural populations, and his lab conducts psychophysical experiments designed to test Bayesian models of human sensory perception.

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