Our brains can rewire themselves in just seconds to compensate for a break in incoming data, suggesting they are even more flexible than previously thought.

We already knew that the brain is constantly adapting throughout our lives, for example by generating new neurons well into adulthood. But just how quickly can it adapt – and does it always involve creating new circuits?

To investigate these questions, Daniel Dilks and his colleagues at the Massachusetts Institute of Technology took advantage of the blind spots that occur naturally in our eyes where the optic nerve exits the retina. The brain normally combines images captured by both eyes to fill in the resulting gaps in vision, but Dilks prevented this in 48 volunteers by patching one eye.

Blind shapes

After identifying where the blind spot was for each volunteer’s other eye, he then presented an image of a square right next to it. The volunteers initially saw a square, but reported that within seconds it had morphed into a rectangle, by extending its edge into the blind spot.


The change in what the volunteers saw was so fast, Dilks says, that it must be due to the brain redirecting signals through pre-existing circuits rather than forging new connections. The team concludes that the neurons which would normally fill the blind spot using data from the patched eye compensated by stealing data from neighbouring neurons that were “seeing” the square, making it appear like a rectangle.

Journal reference: Journal of Neuroscience, (DOI: 10.1523/jneurosci.1557-09.2009).