Blinking temporarily switches off parts of your brain, according to
a study published in the latest issue of Current Biology. The
University College London (UCL) team found that the brain actively
shuts down parts of the visual system each time you blink, even if
light is still entering the eyes. Their findings could explain why you
don't notice your own blinks.
Scientists from the UCL Institute of Neurology designed a special
device to study the effects of blinking on the brain. The device, made
with fibre optic cable, was placed in the mouth of volunteers wearing
light proof goggles and lying in a functional magnetic resonance
imaging (fMRI) brain scanner.
The optical fibre illuminated the
eyeballs through the roof of the mouth with a strong light, making the
head glow red . Thus, light falling on the retina remained constant
even when the volunteers blinked, enabling scientists to measure the
effects of blinking on brain activity independently of the effect of
eyelid closure on light entering the eye.
The study, funded by the Wellcome Trust, found that blinking
suppressed brain activity in the visual cortex as well as parietal and
prefrontal areas which are usually activated when people become
conscious of visual events or objects in the outside world.
Davina Bristow of the UCL Institute of Neurology says: "Blinking is
necessary to keep the surfaces of the eyes moist. Most people blink
around 15 times a minute and a blink lasts on average 100-150
milliseconds, which means that overall we spend at least 9 days per
"We would immediately notice if the outside world suddenly went
dark, especially if it was happening every few seconds. But we are
rarely aware of our blinks, even though they cause a similar reduction
in the amount of light entering the eye, and this gives us an
uninterrupted view of the world.
"Transiently suppressing the brain areas involved in visual
awareness during blinks may be a neural mechanism for preventing the
brain from becoming aware of the eyelid sweeping down over the pupil
during a blink and the world going dark."
In short, the authors suggest that when we blink, the brain may just miss it.
Notes for Editors
1. For more information or to set up an interview, please contact
Jenny Gimpel at the UCL Media Relations Office on +44 (0)20 7679 9739,
Out of Hours: +44 (0)7917 271364 or e-mail firstname.lastname@example.org . Images are also available from this office.
2. Blinking suppresses the neural response to unchanging retinal
stimulation, by Davina Bristow; John-Dylan Haynes; Richard Sylvester;
Christopher Frith; Geraint Rees, is published in Current Biology on 26