The effect of retinal inhibitory interneurons on ganglion cell spiking during saccade-like stimulation: model and experiments

Your eyes are probably performing saccades scrolling on the screen, or on the page you printed out to read the abstract of this thesis. Yet you do not have the perception that they are moving, you do not realize what happens during these movements, your perception is remaining stable, you have perfect control of your visual scene. This experienced stability is partially accompanied by an impairment of the visual system’s sensitivity, a phenomenon known as saccadic suppression. It has been documented that this phenomenon already starts at the retinal level and it is supported by three mechanisms. Two of them have been hypothesized to be mediated by lateral networks of retinal inhibitory interneurons. More precisely by wide field amacrine cells' and horizontal cells' networks. However, the underlying physiological aspects remain unclear. Here, to develop intuitions on the role of these networks in retinal saccadic suppression, we present a phenomenological model that can encompass their likely functioning. We designed the architecture and functionality of the lateral networks of interneurons based on their actual physiological and functional properties. We validated our model with previously reported data and new data collected through the introduction of a novel experimental protocol. We demonstrated the capability of the model to capture the functionality of the wide field amacrine cells network in retinal saccadic suppression. Furthermore, we found that the crucial feature of such a network in mediating suppression is the interaction time. We observed, both in model predictions and experiments, that the horizontal cells network might play a role in retinal saccadic suppression. However, it apparently does not act univocally, its influence in modulating RGCs activity varies among cell types.