On Temporal Robustness & Brain-State Stability of Functional Connectivity in Mouse Primary Visual Area V1 compared to Higher Visual Area AL

Abstract

Understanding how the structure of functional connectivity in the visual cortex changes over time and across brain states is crucial for elucidating the mechanisms by which neurons coordinate to process information and support behavior. Higher-order visual areas in mice are known to exhibit more distinct, segregated functional roles compared to the primary visual cortex (V1) [1], and they maintain stimulus representations over extended time scales [2]. However, the stability of the architecture of their functional connectivity across time and brain states remains less understood. In vivo mesoscopic two-photon calcium imaging was used to simultaneously record activity from thousands of neurons across V1 and the extra-striate anterolateral area (AL) in mice, during both visual stimulation (optical-flow/motion) and at resting state (i.e., absence of stimulus). We then applied the spike time-tiling (STTC) coefficient [3] to estimate the pairwise correlations of the neuronal firing and form the functional connectivity at the cell resolution. We then comparatively analyzed the functional connections within area AL and V1 under both stimulus-driven and resting-state conditions. The functional connectivity within AL remains consistently more robust over time than in area V1. Moreover, the structure of the functional connectivity in AL exhibits a smaller change between these two conditions compared to V1, indicating that functional connectivity derived from spontaneous activity more faithfully reflects the functional network architecture elicited by visual stimulation in this higher-order area. Finally, during the resting state, AL activity and functional connectivity are less dependent on pupil size than those of V1, indicating that arousal exerts a weaker modulatory effect on AL compared to V1.