Projections of the Mouse Primary Visual Cortex

Arbora Resulaj

doi:10.3389/fncir.2021.751331

Abstract

Lesion or damage to the primary visual cortex (V1) results in a profound loss of visual perception in humans. Similarly, in mice, optogenetic silencing of V1 profoundly impairs discrimination of orientated gratings. V1 is thought to have such a critical role in perception in part due to its position in the visual processing hierarchy. It is the first brain area in the neocortex to receive visual input, and it distributes this information to more than 18 brain areas. Here I review recent advances in our understanding of the organization and function of the V1 projections in the mouse. This progress is in part due to new anatomical and viral techniques that allow for efficient labeling of projection neurons. In the final part of the review, I conclude by highlighting challenges and opportunities for future research.

Highlights

V1 is the first cortical area to receive visual input (Felleman and Van Essen, 1991; Siegle et al, 2021). It performs numerous computations locally, and it distributes information to more than 18 brain areas (Oh et al, 2014; Zhang et al, 2016; Han et al, 2018; Harris et al, 2019). These projections to the different brain areas are thought to play distinct roles: projections to higher visual cortical areas (Wang and Burkhalter, 2007) are thought to extract visual features that match the features represented by higher visual cortical areas, projections to the thalamus are thought to provide alternative routes of communication between the cortical areas, and projections to major subcortical areas like the superior colliculus, striatum, or the brainstem nuclei, are thought to modulate simple or innate behaviors (Khibnik et al, 2014; Zhao et al, 2014; Liang et al, 2015; Liu et al, 2016; Ruediger and Scanziani, 2020; Tang and Higley, 2020)
This review focuses on recent studies that reveal, or have started to reveal, general principles about V1 projections: whether the different V1 projections are anatomically segregated, whether V1 projections send specialized information to different target areas, and whether we can pinpoint a distinct behavioral role to a unique V1 projection
Tang and Higley (2020) showed that optogenetically suppressing V1 neurons projecting to the pons impaired a visually cued eye blink conditioning response, while suppressing V1 neurons projecting to the striatum had no effect. Another example showing distinct roles in behavior for different V1 projections comes from Ruediger and Scanziani (2020), where the authors permanently ablated either V1 neurons projecting to the striatum or V1 neurons projecting to the superior colliculus during a visual detection task

Summary

Projections of the Mouse Primary Visual Cortex

Lesion or damage to the primary visual cortex (V1) results in a profound loss of visual perception in humans. V1 is thought to have such a critical role in perception in part due to its position in the visual processing hierarchy. It is the first brain area in the neocortex to receive visual input, and it distributes this information to more than 18 brain areas. I review recent advances in our understanding of the organization and function of the V1 projections in the mouse. This progress is in part due to new anatomical and viral techniques that allow for efficient labeling of projection neurons.

INTRODUCTION

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FUTURE DIRECTIONS