14 DAY TRIAL // Have you ever wondered how we can see a still image of the environment, while constantly shifting our gaze? A new research carried out at the University of M?nster, Germany, and published in "PLoS Comput Biol" shows that this shift in attention induces a short compression of visual space.
The team has found a model of brain function using eye movement signals to create a cerebral representation of objects placed at the future eye position, based on a temporary loss of spatial accuracy, a proof for a direct connection between visual perception and eye-movement control. Our eyes move 2-3 times a second without noticing, and each gaze change provokes an array of internal brain processes with rapid timing.
The gaze change occurs soon after a change of attention towards the new visual target, some 50 milliseconds later. During this period, the sensitivity of visual neurons in many brain nuclei rises, so that they react more strongly to stimuli around the visual target just before the eye movement.
The team investigated a detailed computational model of the visual cortical maps, to see the effects of these sensitivity shifts in the perception of spatial location. The objects presented just before the eye movement seem to be located at the gaze target, rather than at their true spatial location.
Neurons in some brain nuclei clearly appeared to change their receptive field (the visual direction to which they react) before the eye movement. Analyzing the receptive field shifts, the team found that the brain actively chose neurons for processing visual data around the target.
This rise in processing capacity could enable us to detect details of the object before actually watching it, so that we have the impression of a stable world, despite our eye movement. The newly found pattern of brain visual activity could lead to the development of new artificial vision systems.