Our lab is participating with two presentations at this year’s COSYNE 2020 meeting, taking place in Denver, CO. The meeting focuses on computational and systems neuroscience, and it addresses a multi-disciplinary audience interested in both experimental work as well as theoretical and computational approaches.
In our first presentation, Antimo Buonocore and Matthias Baumann describe some highly intriguing observations that we have made about visual pattern analysis by motor neurons! We studied an oculomotor nucleus very deep in the brainstem, which contains so-called OPN neurons (omnidirectional pause neurons). These neurons act as a machine-like gating mechanism to prevent or allow the triggering of saccadic eye movements of all sizes and directions. They are therefore usually thought of as purely motor neurons. We studied them from a sensory perspective, and we found that they exhibit visual pattern analysis capabilities as if they are an early visual area!! We also explored the causal role of these capabilities by comparing microstimulation of OPN neurons to that of superior colliculus (SC) and also primary visual cortex (V1) neurons. Our results provide a mechanistic insight into how the brain maintains robustness and flexibility when reacting to the outside world.
In our second presentation, Xiaoguang Tian (now a post-doc with Afonso Silva) and Tong Zhang use a very cool causal manipulation to demonstrate how foveal action can control extra-foveal vision. In this work, we made a strong test of some of our earlier predictions on the relationships between microsaccades and covert visual attention. Specifically, we recently suggested that peri-microsaccadic changes in brain state are sufficient to explain attentional effects in some of the most classic attentional cueing experiments in the field of cognitive neuroscience. While our previous work provided strong evidence for this idea, a remaining question has been on the possible direction of causality. That is, was it the case that peripheral attention was enhanced and this triggered a microsaccade, or was it the case that the mere act of generating a microsaccade was sufficient to cause peripheral attentional effects? We now tested the latter possibility and found compelling support for it. We used our real-time gaze-contingent display technique to experimentally force a tiny foveal motor error of <3 min arc regardless of where gaze was directed. We showed that this tiny stimulus manipulation was entirely sufficient to completely shape the distributions of microsaccades at will, which gave us unprecedented control over the way the subjects were employing microsaccades in our experimental tasks. We then checked peripheral sensitivity at different directions relative to the experimentally controlled microsaccade motor programs. We found, both neuronally and perceptually, that experimental control over microsaccades was sufficient to cause peripheral attention-like performance changes! This work provides a nice closure on some of the most outstanding questions on the relationship between microsaccades and covert visual attention in the field, including our confusing (at the time) observations already in 2002 (!) that no attentional effects occurred when no microsaccades occurred.