Viduolyte, A. | Search bioRxiv

bioRxiv2025

Topographic alignment of auditory inputs to the visual cortex

Sensory cortical areas send long-range projections to cortical areas from other sensory modalities, supporting multisensory integration to generate a unified representation of the external world. However, the organizational principles underlying these extensive cross-modal connections remain poorly understood. In this study, we investigated the anatomical and functional organisation of auditory cortex inputs in the visual cortex. We found that populations of anatomically segregated auditory cortex neurons project to different visual cortical areas, broadcasting distinct auditory information to the dorsal and ventral visual processing streams. While sound frequency information was homogenously distributed across visual cortical areas, sound location information was differentially broadcast across the visual cortex. Specifically, sound azimuth and elevation were differentially encoded across visual cortical areas and streams matching the retinotopic bias of the target area. These findings suggest that cross-modal cortico-cortical connections follow a simple rule whereby specialised projection pathways are topographically aligned with the organisational principles of the target sensory area, ensuring spatially coherent integration of multisensory signals.

neuroscience↗

bioRxiv2021

A transcriptomic axis predicts state modulation of cortical interneurons

Transcriptomics has revealed the exquisite diversity of cortical inhibitory neurons1-7, but it is not known whether these fine molecular subtypes have correspondingly diverse activity patterns in the living brain. Here, we show that inhibitory subtypes in primary visual cortex (V1) have diverse correlates with brain state, but that this diversity is organized by a single factor: position along their main axis of transcriptomic variation. We combined in vivo 2-photon calcium imaging of mouse V1 with a novel transcriptomic method to identify mRNAs for 72 selected genes in ex vivo slices. We used transcriptomic clusters (t-types)4 to classify inhibitory neurons imaged in layers 1-3 using a three-level hierarchy of 5 Families, 11 Classes, and 35 t-types. Visual responses differed significantly only across Families, but modulation by brain state differed at all three hierarchical levels. Nevertheless, this diversity could be predicted from the first transcriptomic principal component, which predicted a cell types brain state modulation and correlations with simultaneously recorded cells. Inhibitory t-types with narrower spikes, lower input resistance, weaker adaptation, and less axon in layer 1 as determined in vitro8 fired more in resting, oscillatory brain states. Transcriptomic types with the opposite properties fired more during arousal. The former cells had more inhibitory cholinergic receptors, and the latter more excitatory receptors. Thus, despite the diversity of V1 inhibitory neurons, a simple principle determines how their joint activity shapes state-dependent cortical processing.

neuroscience↗