Mixed functional microarchitectures for orientation selectivity in the mouse primary visual cortex.

Satoru Kondo,Takashi Yoshida,Kenichi Ohki

doi:10.1038/ncomms13210

Abstract

A minicolumn is the smallest anatomical module in the cortical architecture, but it is still in debate whether it serves as functional units for cortical processing. In the rodent primary visual cortex (V1), neurons with different preferred orientations are mixed horizontally in a salt and pepper manner, but vertical functional organization was not examined. In this study, we found that neurons with similar orientation preference are weakly but significantly clustered vertically in a short length and horizontally in the scale of a minicolumn. Interestingly, the vertical clustering is found only in a part of minicolumns, and others are composed of neurons with a variety of orientation preferences. Thus, the mouse V1 is a mixture of vertical clusters of neurons with various degrees of orientation similarity, which may be the compromise between the brain size and keeping the vertical clusters of similarly tuned neurons at least in a subset of clusters.

Highlights

A minicolumn is the smallest anatomical module in the cortical architecture, but it is still in debate whether it serves as functional units for cortical processing
Previous studies with two-photon calcium imaging showed that neurons with different preferred orientations are mixed in a salt and pepper manner parallel to the cortical surface in the primary visual cortex of rodents[14,15,16]
We found that clustering of neurons with similar orientation preferences is limited to the same microcolumn, the spatial frequency (SPF) is not related to microcolumns, and the clustering of neurons with similar retinotopic positions is larger than microcolumns, all resembling the functional architecture of minicolumns

Summary

Introduction

A minicolumn is the smallest anatomical module in the cortical architecture, but it is still in debate whether it serves as functional units for cortical processing. Previous studies with two-photon calcium imaging showed that neurons with different preferred orientations are mixed in a salt and pepper manner parallel to the cortical surface in the primary visual cortex of rodents[14,15,16]. These studies did not reveal whether neurons with similar orientation selectivity exhibit a completely disorganized structure or a vertically organized structure when analyzed three-dimensionally. We used this imaging technique to investigate the 3D functional architecture of neurons in the primary visual cortex of mice with complete sampling of neurons in local volumes, and analysed the similarity of the response selectivity of neurons within minicolumns

Methods

Results

Conclusion