Apical length governs computational diversity of layer 5 pyramidal neurons

Abstract
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Abstract

Anatomical similarity across the neocortex has led to the common assumption that the circuitry is modular and performs stereotyped computations. Layer 5 pyramidal neurons (L5PNs) in particular are thought to be central to cortical computation because of their extensive arborisation and nonlinear dendritic operations. Here, we demonstrate that computations associated with dendritic Ca²⁺ plateaus in mouse L5PNs vary substantially between the primary and secondary visual cortices. L5PNs in the secondary visual cortex show reduced dendritic excitability and smaller propensity for burst firing. This reduced excitability is correlated with shorter apical dendrites. Using numerical modelling, we uncover a universal principle underlying the influence of apical length on dendritic backpropagation and excitability, based on a Na⁺ channel-dependent broadening of backpropagating action potentials. In summary, we provide new insights into the modulation of dendritic excitability by apical dendrite length and show that the operational repertoire of L5PNs is not universal throughout the brain.

Data availability

All data, analysis scripts and simulation code is available at https://github.com/ranczlab/Galloni.etal.2020

Article and author information

Author details

Alessandro R Galloni

Cortical Circuits Laboratory, The Francis Crick Institute, London, United Kingdom

Competing interests
The authors declare that no competing interests exist.
Aeron Laffere

Department of Psychological Sciences, Birkbeck, University of London, London, United Kingdom

Competing interests
The authors declare that no competing interests exist.

"This ORCID iD identifies the author of this article:" 0000-0001-8307-0079
Ede Rancz

Cortical Circuits Laboratory, The Francis Crick Institute, London, United Kingdom

For correspondence
ede.rancz@crick.ac.uk

Competing interests
The authors declare that no competing interests exist.

"This ORCID iD identifies the author of this article:" 0000-0002-7951-1385

Funding

Wellcome (Sir Henry Dale Fellowship,104285/B/14/Z)

Ede Rancz

Royal Society (Sir Henry Dale Fellowship,104285/B/14/Z)

Ede Rancz

Boehringer Ingelheim Fonds (PhD Scholarship)

Alessandro R Galloni

Francis Crick Institute (PhD Scholarhip)

Alessandro R Galloni

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 animal experiments were prospectively approved by the local ethics panel of the Francis Crick Institute (previously National Institute for Medical Research) and the UK Home Office under the Animals (Scientific Procedures) Act 1986 (PPL: 70/8935). All surgery was performed under isoflurane anesthesia, and every effort was made to minimize suffering.

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.