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bioRxiv · 10.1101/113019

Visually driven neuropil activity and information encoding in mouse area V1

Lee, S.·Meyer, J.·Smirnakis, S.
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Abstract

Spontaneous calcium fluorescence recorded from large cortical neuropil patches strongly correlates with the electro-corticogram, and is thought to arguably reflect primarily pre-synaptic inputs. Here we used in vivo 2-photon imaging with Oregon Green Bapta (OGB) to study neuropil visual responses to moving gratings in layer 2/3 of mouse area V1. We found neuropil responses to be more reliable and more strongly modulated than neighboring somatic activity. Furthermore, stimulus independent modulations in neuropil activity, i.e. noise correlations, were highly coherent across the cortical surface, up to distances of at least 200 m. Pairwise neuropil-to-neuropil-patch noise correlation strength was much higher than cell-to-cell noise correlation strength and depended strongly on brain state, decreasing in quiet wakefulness relative to light anesthesia. The profile of neuropil noise correlation strength decreased gently with distance, dropping by ~12% at a distance of 200 m. This was comparatively slower than the profile of cell-to-cell noise correlations, which dropped by ~30% at 200 m. Interestingly, in spite of the \"salt & pepper\" organization of orientation and direction encoding across mouse V1 neurons, populations of neuropil patches, even of moderately large size (radius ~100m), showed high accuracy for discriminating perpendicularly moving gratings commensurate to the accuracy of corresponding cell populations. These observations underscore the dynamic nature of the functional organization of neuropil activity.\n\nConflict of InterestThe authors declare that no competing interests exist.

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Lee, S., Meyer, J., Smirnakis, S.. 2017-03-06. Visually driven neuropil activity and information encoding in mouse area V1. https://doi.org/10.1101/113019

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