Experimental testing of a sensorimotor origin of saccadic suppression compared with a control task

Saccadic suppression has been studied for a long time and is a phenomenon during which the brain selectively blocks the visual signal during saccadic eye movements. The general opinion is that its purpose serves the stabilization of our perception, which, would be otherwise disturbed by the movement. Even though this explanation seems convincing, it presents some inconsistencies in terms of timing and intensity. A recent theoretical model of saccadic control, sharing perception and sensorimotor resources, faithfully reproduces the behaviour of real saccades. The architecture of this model allows to highlight the fact that the saccadic suppression would be a consequence of efficient Bayesian state estimation, in such way that the noise in the motor command would reduce the importance given to the visual sensory information. In the present work, the inverse statement has been tested experimentally to challenge the hypothesis, since the model is also built such that increasing the weight of the sensory feedback in the estimation would impair the outcome and disturb the motor command. Participants underwent a task during which their perception was enhanced during saccades, modulating the intensity of the suppression, in order to measure the outcome on the saccadic movement. A control task was added to verify results from a former work, confirming that with an increased sensory input, the behaviour of the saccades differs from the regular main sequence. Those results support the idea that saccadic suppression could originate from optimal sensorimotor estimation. However, those results must be seen as a plausible explanation in the framework of sensorimotor control, and the link with physical neural circuits needs to be further investigated.