Kanold, P. O. | Search bioRxiv

bioRxiv2017

Spatial organization of the mouse auditory cortex to sound dynamics revealed using automated image segmentation

Sound stimuli are characterized by their rich spectral and temporal dynamic properties. Individual neurons in auditory cortex (ACX) encode both spectral and temporal aspects of sounds e.g. sound onset and/or offset. While the different fields of the ACX show gradients of frequency selectivity the large-scale organization of sound dynamics is unknown. We used widefield imaging of GCaMP6s in awake mouse ACX combined with a novel unsupervised image segmentation technique to investigate the spatiotemporal representation of sound onset and offset. Using this technique, we identified known auditory fields but also detected novel ACX areas. Furthermore, we found that ACX areas differed in their responses to tone onset and offset. Multiple areas were preferentially activated by tone offset, and on-response areas were more spatially localized than off-response areas. We also found tonotopy in off-responses. Together our results demonstrate a different spatial distribution of neurons across ACX for processing sound onsets versus offsets.

neuroscience↗

bioRxiv2016

Fast and Stable Signal Deconvolution via Compressible State-Space Models

Abstract-Objective:Common biological measurements are in the form of noisy convolutions of signals of interest with possibly unknown and transient blurring kernels. Examples include EEG and calcium imaging data. Thus, signal deconvolution of these measurements is crucial in understanding the underlying biological processes. The objective of this paper is to develop fast and stable solutions for signal deconvolution from noisy, blurred and undersampled data, where the signals are in the form of discrete events distributed in time and space. Methods: We introduce compressible state-space models as a framework to model and estimate such discrete events. These state-space models admit abrupt changes in the states and have a convergent transition matrix, and are coupled with compressive linear measurements. We consider a dynamic compressive sensing optimization problem and develop a fast solution, using two nested Expectation Maximization algorithms, to jointly estimate the states as well as their transition matrices. Under suitable sparsity assumptions on the dynamics, we prove optimal stability guarantees for the recovery of the states and present a method for the identification of the underlying discrete events with precise confidence bounds. Results: We present simulation studies as well as application to calcium deconvolution and sleep spindle detection, which verify our theoretical results and show significant improvement over existing techniques. Conclusion: Our results show that by explicitly modeling the dynamics of the underlying signals, it is possible to construct signal deconvolution solutions that are scalable, statistically robust, and achieve high temporal resolution. Significance: Our proposed methodology provides a framework for modeling and deconvolution of noisy, blurred, and undersampled measurements in a fast and stable fashion, with potential application to a wide range of biological data.

bioengineering↗