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MouseV1. Kenneth Miller. Understanding V1 circuit dynamics and computations

Title: Fine spatial organization of orientation tuning in mouse visual cortex

Abstract: 

The absence of spatial organization in orientation tuning had been thought as a major feature of the rodent primary visual cortex (V1). However, recent experimental discoveries have been revisiting and challenging this view. Population imaging studies have suggested that nearby neurons in the layer 2/3 (L2/3) of mouse V1 tend to have stronger tuning similarity than that of distant neuron pairs, indicating a localized spatial clustering of stimulus feature preference (Ringach et al. 2016, Jimenez et al. 2018, Kondo et al. 2016). However, the spatial scale of clustering is still in debate: either spread over hundreds of microns (Ringach et al. 2016), or limited to the scale of tens of microns (Kondo et al. 2016). Those differences could reflect distinct scales of local feedforward/recurrent cortical connectivity, so an accurate measurement of the spatial profile of local clustering will shed light on the underlying neuronal circuits, yielding way to circuit-based mechanisms of visual processing in rodent V1. Here using two-photon calcium imaging, we measured the orientation tuning properties of L2/3 neurons in mouse V1. We found a significant spatial clustering of tuning, but horizontally localized in only approximately 20 um, which is typically the average distance between horizontally neighboring neurons. To understand this narrow clustering, we explored a spiking neuron network model of L2/3 and L4 of mouse V1. Building on past models with broad recurrent wiring over 200 um (Rosenbaum et al., 2017; Huang et al., 2019) we additionally considered an excess connecting probability over a narrow 20 um range. A spatially narrow local tuning similarity matching our data emerges for even weak narrow connectivity, effectively adding only a few extra local connections per neuron. Our combined experimental and modeling work argue for a fine spatial scale of wiring between adjacent neurons in mouse V1.

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