Blinking suppresses the neural response to unchanging retinal stimulation.
Blinks profoundly interrupt visual input but are rarely noticed, perhaps because of blink suppression, a visual-sensitivity loss that begins immediately prior to blink onset. Blink suppression is thought to result from an extra-retinal signal that is associated with the blink motor command and may act to attenuate the sensory consequences of the motor action. However, the neural mechanisms underlying this phenomenon remain unclear. They are challenging to study because any brain-activity changes resulting from an extra-retinal signal associated with the blink motor command are potentially masked by profound neural-activity changes caused by the retinal-illumination reduction that results from occlusion of the pupil by the eyelid. Here, we distinguished direct top-down effects of blink-associated motor signals on cortical activity from purely mechanical or optical effects of blinking on visual input by combining pupil-independent retinal stimulation with functional MRI (fMRI) in humans. Even though retinal illumination was kept constant during blinks, we found that blinking nevertheless suppressed activity in visual cortex and in areas of parietal and prefrontal cortex previously associated with awareness of environmental change. Our findings demonstrate active top-down modulation of visual processing during blinking, suggesting a possible mechanism by which blinks go unnoticed.
Bristow
Davina
D
Wellcome Department of Imaging Neuroscience, Institute of Neurology, University College London, 12 Queen Square, London WC1N 3BG, United Kingdom. dbristow@fil.ion.ucl.ac.uk
Haynes
John-Dylan
JD
Sylvester
Richard
R
Frith
Christopher D
CD
Rees
Geraint
G
D000328:Adult; D001767:Blinking / Q000502:physiology*; D001921:Brain / Q000502:physiology*; D004525:Efferent Pathways / Q000502:physiology*; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D010775:Photic Stimulation; D012160:Retina / Q000502:physiology*; D014795:Visual Pathways / Q000502:physiology*; D014796:Visual Perception / Q000502:physiology*