High and asymmetric somato-dendritic coupling of V1 layer 5 neurons independent of visual stimulation and locomotion

Abstract
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Abstract

Active dendrites impact sensory processing and behaviour. However, it remains unclear how active dendritic integration relates to somatic output in vivo. We imaged semi-simultaneously GCaMP6s signals in the soma, trunk and distal tuft dendrites of layer 5 pyramidal neurons in the awake mouse primary visual cortex. We found that apical tuft signals were dominated by widespread, highly correlated calcium transients throughout the tuft. While these signals were highly coupled to trunk and somatic transients, the frequency of calcium transients was found to decrease in a distance-dependent manner from soma to tuft. Ex vivo recordings suggest that low-frequency back-propagating action potentials underlie the distance-dependent loss of signals, while coupled somato-dendritic signals can be triggered by high-frequency somatic bursts or strong apical tuft depolarization. Visual stimulation and locomotion increased neuronal activity without affecting somato-dendritic coupling. High, asymmetric somato-dendritic coupling is therefore a widespread feature of layer 5 neurons activity in vivo.

Data availability

Raw data (changes of fluorescence over time) are provided in all the main figures (figure 1-4) and in two supplementary figures.Additionally, we provide two data source videos (supplementary video 1 and supplementary video 2).We are willing to share all raw data (videos) upon acceptance of the manuscript. Due to the large volume of imaging data sets, we will give access to a local dedicated server from Rochefort lab.All analyses were performed using custom-written scripts in MATLAB, which will be freely available via GitHub repository (https://github.com/rochefort-lab), upon acceptance of the manuscript.

Article and author information

Author details

Valerio Francioni

Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh, United Kingdom

Competing interests
The authors declare that no competing interests exist.
Zahid Padamsey

Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh, United Kingdom

Competing interests
The authors declare that no competing interests exist.
Nathalie L Rochefort

Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh, United Kingdom

For correspondence
n.rochefort@ed.ac.uk

Competing interests
The authors declare that no competing interests exist.

"This ORCID iD identifies the author of this article:" 0000-0002-3498-6221

Funding

Wellcome (102857/Z/13/Z)

Nathalie L Rochefort

Royal Society (102857/Z/13/Z)

Nathalie L Rochefort

University Of Edinburgh (PhD fellowship)

Valerio Francioni

Simons Initiative for the Developing Brain (Project grant)

Nathalie L Rochefort

European Union's FP7 program (CIG 631770)

Nathalie L Rochefort

RS MacDonald Charitable Trust (Seedcorn Grant)

Nathalie L Rochefort

Royal Society (Royal Commission for the Exhibition 1851)

Zahid Padamsey

The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.

Ethics

Animal experimentation: All experiments and procedures involving animals were approved by the University of Edinburgh Animal Welfare and the ethical review board (AWERB) and performed under the appropriate PIL and PPL license from the UK Home Office in accordance with the Animal (Scientific Procedures) act 1986 and the European Directive 86/609/EEC on the protection of animals used for experimental purposes.

Copyright

This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.