Laminar-specific cortico-cortical loops in mouse visual cortex

Abstract

Many theories propose recurrent interactions across the cortical hierarchy, but it is unclear if cortical circuits are selectively wired to implement looped computations. Using subcellular channelrhodopsin-2-assisted circuit mapping in mouse visual cortex, we compared feedforward (FF) or feedback (FB) cortico-cortical synaptic input to cells projecting back to the input source (looped neurons) with cells projecting to a different cortical or subcortical area. FF and FB afferents showed similar cell-type selectivity, making stronger connections with looped neurons than with other projection types in layer (L) 5 and L6, but not in L2/3, resulting in selective modulation of activity in looped neurons. In most cases, stronger connections in looped L5 neurons were located on their apical tufts, but not on their perisomatic dendrites. Our results reveal that cortico-cortical connections are selectively wired to form monosynaptic excitatory loops and support a differential role of supragranular and infragranular neurons in hierarchical recurrent computations.

How Cortical Circuits Implement Cortical Computations: Mouse Visual Cortex as a Model

“…These outputs to HVAs are reciprocal. Neurons in V1 receive feedback from the areas to which they project to form loops with cellular, laminar, and functional specificity (D'Souza et al 2016, Marques et al 2018, Young et al 2021. These feedback projections modulate responses in V1, including amplification of tuning properties and mediating contextual modulations (Vangeneugden et al 2019, Huh et al 2018, Keller et al 2020b).…”

Dendritic domain-specific sampling of long-range axons shapes feedforward and feedback connectivity of L5 neurons

“…V2M is defined in the Mouse Brain In Stereotaxic Coordinates atlas (Franklin & Paxinos 2007) which can be used to guide viral injections. Furthermore, as this atlas is based on cytoarchitecture, thus V2M can be visually distinguished and selectively targeted in slice recordings, as has previously been done (Galloni et al 2020, Young et al 2021. For whole-brain rabies tracing, on the other hand, we adopted the more recently developed Allen Common Coordinate Framework (CCFv3, (Wang et al 2020a).…”

Developmental plasticity in visual cortex is necessary for normal visuomotor integration and visuomotor skill learning

“…This, combined with the fact that CaMKII expression is higher in superficial L2/3 neurons than L4 and L5 neurons (Lein, 2007;Tighilet et al, 1998), could result in an increased effect of the CaMKII inhibition in superficial synapses. Long-range cortical input, which is thought to carry motor-related input to V1 (Leinweber et al, 2017), arrives preferentially on more superficial synapses than the bottom-up visual input (Park et al, 2019;Petreanu et al, 2009;Young et al, 2021).…”