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Ashby, D. M.

Publications and source records attributed to Ashby, D. M..

2 recordsLinked to original sources

A Markovian neural barcode representing mesoscale cortical spatiotemporal dynamics.

Mesoscale cortical dynamics consist of stereotyped patterns of recurring activity motifs, however the constraints and rules governing how these motifs assemble over time is not known. Here we propose a Continuous Time Markov Chain model that probabilistically describes the temporal sequence of activity motifs using Markov Elements derived using semi-binary non-negative matrix factorization. Although derived from a discovery sample, these can be applied to new recordings from new mice. Unwrapping the associated transition probability matrix creates a Markovian neural barcode describing the probability of Markov element transitions as a compact and interpretable representation of neocortical dynamics. We show broad utility across a range of common mesoscale cortical imaging applications, ranging from time-locked events to pathological models. Moreover, it allows the discovery of new and emergent Markov Elements that unmask the flexibility of constraints governing cortical dynamics. The Markovian neural barcode provides a novel and powerful tool to characterize cortical function.

neuroscience↗

Critical role of de novo LTD in the formation and maintenance of hippocampal CA1 place-cell fields

Synaptic plasticity mechanisms may help shape hippocampal place field representations of novel environments, yet direct evidence for how this occurs is lacking. Using multi-channel recordings in freely moving rats, we demonstrate that novelty exploration results in widespread de novo long-term depression (LTD) at hippocampal CA1 synapses in a pathway-specific manner, while blockade of LTD expression impairs the maintenance of newly formed place fields. This study therefore reveals an unrecognized role for LTD in the formation and maintenance of hippocampal place fields in novel environments.

neuroscience↗