Quest for good vision without peripheries - behavioral and fMRI evidence

In healthy vision, bright slow-motion stimuli are primarily processed by regions of the visual system receiving input from the central part of the scene, while processing of the dark fast-motion stimuli is more dependent on the peripheral visual input. We tested 31 retinitis pigmentosa patients (RP) with long-term loss of peripheral photoreceptors and healthy controls with temporarily limited peripheral vision. We measured motion-based acuity, using random-dot kinematograms, establishing individual thresholds for differentiating circle from an ellipse. fMRI session with the task difficulty set at the constant level followed. We showed that limiting vision in controls does not affect the motion-acuity thresholds, but results in brain activations, different from RP patients, indicating prompt implementation of the perceptually successful strategy. Impaired motion-acuity in RP patients led to decreased brain activations compared to controls with full and limited vision and included strong response within peripheral primary visual areas V1-3. Importantly, lower activations in MT+/V5, in salience-processing cortices and in superior temporal cortex in RP patients were also detected in controls with limited peripheral vision, revealing brain networks which compensate for loss of peripheral vision.