Modeling circuit mechanisms of opposing cortical responses to visual flow perturbations

In an ever-changing visual world, animals' survival depends on their ability to perceive and respond to rapidly changing motion cues. The primary visual cortex (V1) is at the forefront of this sensory processing, orchestrating neural responses to perturbations in visual flow. However, the underlying neural mechanisms that lead to distinct cortical responses to such perturbations remain enigmatic. In this study, our objective was to uncover the neural dynamics that govern V1 neurons' responses to visual flow perturbations using a biologically realistic computational model. By subjecting the model to sudden changes in visual input, we observed opposing cortical responses in excitatory layer 2/3 (L2/3) neurons, namely, depolarizing and hyperpolarizing responses. We found that this segregation was primarily driven by the competition between external visual input and recurrent inhibition, particularly within L2/3 and L4. This division was not observed in excitatory L5/6 neurons, suggesting a more prominent role for inhibitory mechanisms in the visual processing of the upper cortical layers. Our findings share similarities with recent experimental studies focusing on the opposing influence of top-down and bottom-up inputs in the mouse primary visual cortex during visual flow perturbations. This study aims to shed light on the intricate dynamics of neural responses within the mouse primary visual cortex (V1) subjected to visual flow perturbations, unraveling the emergence of distinct functional classes of excitatory L2/3 neurons, namely depolarizing (dVf) and hyperpolarizing (hVf) neurons. Through the implementation of a biologically realistic computational model, the investigation highlights the profound impact of synaptic connectivity, inhibitory circuits, and dynamic inputs on shaping these responses. The identified competition by common inhibition mechanism between dVf and hVf neurons, driven not only by long-range thalamic inputs but also by local connectivity, provides new insights into the underlying neural circuitry. This study opens avenues for further exploration into the role of locomotion-related inputs in modulating neural responses, offering a comprehensive framework for future investigations into sensory perception and neural coding.