@article {67287, title = {Neural Correlates of Cognition in Primary Visual versus Neighboring Posterior Cortices during Visual Evidence-Accumulation-based Navigation}, journal = {bioRxiv}, year = {2019}, month = {03/2019}, abstract = {

Studies of perceptual decision-making have often assumed that the main role of sensory cortices is to provide sensory input to downstream processes that accumulate and drive behavioral decisions. We performed a systematic comparison of neural activity in primary visual (V1) to secondary visual and retrosplenial cortices, as mice performed a task where they should accumulate pulsatile visual cues through time to inform a navigational decision. Even in V1, only a small fraction of neurons had sensory-like responses to cues. Instead, in all areas neurons were sequentially active, and contained information ranging from sensory to cognitive, including cue timings, evidence, place/time, decision and reward outcome. Per-cue sensory responses were amplitude-modulated by various cognitive quantities, notably accumulated evidence. This inspired a multiplicative feedback-loop circuit hypothesis that proposes a more intricate role of sensory areas in the accumulation process, and furthermore explains a surprising observation that perceptual discrimination deviates from Weber-Fechner Law.Highlights / eTOC BlurbMice made navigational decisions based on accumulating pulsatile visual cuesThe bulk of neural activity in visual cortices was sequential and beyond-sensoryAccumulated pulse-counts modulated sensory (cue) responses, suggesting feedbackA feedback-loop neural circuit explains behavioral deviations from Weber{\textquoteright}s LawHighlights / eTOC BlurbIn a task where navigation was informed by accumulated pulsatile visual evidence, neural activity in visual cortices predominantly coded for cognitive variables across multiple timescales, including outside of a visual processing context. Even sensory responses to visual pulses were amplitude-modulated by accumulated pulse counts and other variables, inspiring a multiplicative feedback-loop circuit hypothesis that in turn explained behavioral deviations from Weber-Fechner Law.

}, doi = {10.1101/568766}, url = {https://www.biorxiv.org/content/early/2019/03/06/568766}, author = {Koay, Sue Ann and Thiberge, Stephan Y. and Brody, Carlos D. and Tank, David W.} } @article {67290, title = {Sequential and efficient neural-population coding of complex task information}, journal = {bioRxiv}, year = {2019}, month = {10/2019}, abstract = {

Recent work has highlighted that many types of variables are represented in each neocortical area. How can these many neural representations be organized together without interference, and coherently maintained/updated through time? We recorded from large neural populations in posterior cortices as mice performed a complex, dynamic task involving multiple interrelated variables. The neural encoding implied that correlated task variables were represented by uncorrelated modes in an information-coding subspace. We show via theory that this can enable optimal decoding directions to be insensitive to neural noise levels. Across posterior cortex, principles of efficient coding thus applied to task-specific information, with neural-population modes as the encoding unit. Remarkably, this encoding function was multiplexed with rapidly changing, sequential neural dynamics, yet reliably followed slow changes in task-variable correlations through time. We can explain this as due to a mathematical property of high-dimensional spaces that the brain might exploit as a temporal scaffold.

}, doi = {10.1101/801654}, url = {https://www.biorxiv.org/content/early/2019/10/13/801654}, author = {Koay, Sue Ann and Thiberge, Stephan Y. and Brody, Carlos D. and Tank, David W.} } @article {67281, title = {Specialized coding of sensory, motor and cognitive variables in VTA dopamine neurons}, journal = {Nature}, volume = {570}, year = {2019}, month = {05/2019}, pages = {509 - 513}, abstract = {

There is increased appreciation that dopamine neurons in the midbrain respond not only to reward1\ and reward-predicting cues1,2, but also to other variables such as the distance to reward3, movements4,5,6,7,8,9\ and behavioural choices10,11. An important question is how the responses to these diverse variables are organized across the population of dopamine neurons. Whether individual dopamine neurons multiplex several variables, or whether there are subsets of neurons that are specialized in encoding specific behavioural variables remains unclear. This fundamental question has been difficult to resolve because recordings from large populations of individual dopamine neurons have not been performed in a behavioural task with sufficient complexity to examine these diverse variables simultaneously. Here, to address this gap, we used two-photon calcium imaging through an implanted lens to record the activity of more than 300 dopamine neurons from the ventral tegmental area of the mouse midbrain during a complex decision-making task. As mice navigated in a virtual-reality environment, dopamine neurons encoded an array of sensory, motor and cognitive variables. These responses were functionally clustered, such that subpopulations of neurons transmitted information about a subset of behavioural variables, in addition to encoding reward. These functional clusters were spatially organized, with neighbouring neurons more likely to be part of the same cluster. Together with the topography between dopamine neurons and their projections, this specialization and anatomical organization may aid downstream circuits in correctly interpreting the wide range of signals transmitted by dopamine neurons.

}, issn = {0028-0836}, doi = {10.1038/s41586-019-1261-9}, url = {http://www.nature.com/articles/s41586-019-1261-9}, author = {Engelhard, Ben and Finkelstein, Joel and Cox, Julia and Fleming, Weston and Jang, Hee Jae and Ornelas, Sharon and Koay, Sue Ann and Thiberge, Stephan Y. and Daw, Nathaniel D. and Tank, David W. and Witten, Ilana B.} } @article {67283, title = {An Accumulation-of-Evidence Task Using Visual Pulses for Mice Navigating in Virtual Reality}, journal = {Frontiers in Behavioral Neuroscience}, volume = {12}, year = {2018}, month = {Jun-03-2018}, abstract = {

The gradual accumulation of sensory evidence is a crucial component of perceptual decision making, but its neural mechanisms are still poorly understood. Given the wide availability of genetic and optical tools for mice, they can be useful model organisms for the study of these phenomena; however, behavioral tools are largely lacking. Here, we describe a new evidence-accumulation task for head-fixed mice navigating in a virtual reality (VR) environment. As they navigate down the stem of a virtual T-maze, they see brief pulses of visual evidence on either side, and retrieve a reward on the arm with the highest number of pulses. The pulses occur randomly with Poisson statistics, yielding a diverse yet well-controlled stimulus set, making the data conducive to a variety of computational approaches. A large number of mice of different genotypes were able to learn and consistently perform the task, at levels similar to rats in analogous tasks. They are sensitive to side differences of a single pulse, and their memory of the cues is stable over time. Moreover, using non-parametric as well as modeling approaches, we show that the mice indeed accumulate evidence: they use multiple pulses of evidence from throughout the cue region of the maze to make their decision, albeit with a small overweighting of earlier cues, and their performance is affected by the magnitude but not the duration of evidence. Additionally, analysis of the mice{\textquoteright}s running patterns revealed that trajectories are fairly stereotyped yet modulated by the amount of sensory evidence, suggesting that the navigational component of this task may provide a continuous readout correlated to the underlying cognitive variables. Our task, which can be readily integrated with state-of-the-art techniques, is thus a valuable tool to study the circuit mechanisms and dynamics underlying perceptual decision making, particularly under more complex behavioral contexts.

}, doi = {10.3389/fnbeh.2018.00036}, url = {http://journal.frontiersin.org/article/10.3389/fnbeh.2018.00036/full}, author = {Pinto, Lucas and Koay, Sue A. and Engelhard, Ben and Yoon, Alice M. and Deverett, Ben and Thiberge, Stephan Y. and Witten, Ilana B. and Tank, David W. and Brody, Carlos D.} }