Skip to main content
Dryad

Data from: Layer 6 corticocortical neurons are a major route for intra and interhemispheric feedback

Weiler, Simon1; Teichert, Manuel2; Margrie, Troy W.1

Published Mar 25, 2025 on Dryad. https://doi.org/10.5061/dryad.8kprr4xzd

Data files

Mar 25, 2025 version files 17.35 MB

Abstract

The neocortex comprises anatomically discrete yet interconnected areas that are symmetrically located across the two hemispheres. Determining the logic of these macrocircuits is necessary for understanding high level brain function. Here we have mapped the areal and laminar organization of the ipsilateral and contralateral cortical projection onto the primary visual, somatosensory and motor cortices in mice. We find that although the ipsilateral hemisphere is the primary source of cortical input, there is substantial contralateral symmetry regarding the relative contribution and areal identity of input. Laminar analysis of these input areas show that excitatory Layer 6 corticocortical cells (L6 CCs) are a major projection pathway within and between the two hemispheres. Analysis of the relative contribution of inputs from supra- (feedforward) and infra-granular (feedback) layers, reveals that contra-hemispheric projections reflect a dominant feedback organization compared to their ipsi-cortical counterpart. The magnitude of the interhemispheric difference in hierarchy was largest for sensory and motor projection areas compared to frontal, medial or lateral brain areas due to a proportional increase in input from L6 neurons. L6 CCs therefore not only mediate long-range cortical communication but also reflect its inherent feedback organization.