When we suddenly get an flash of inspiration, we can practically feel the light bulb click on in our head. But after the “Aha!” moment, how do the things we learn tend to stay remembered?

“Much of memory research involves repetitive, rote learning,” says Kelly Ludmer, a research student in Prof. Yadin Dudai’s neurobiology group at the Weizmann Institute of Science in Rehovot.

“But in fact, we regularly absorb large blocks of information in the blink of an eye and remember things quite well from single events. Insight is an example of a one-time event that is often well-preserved in memory.”

To find out how, Ludmer, Dudai and Prof. Nava Rubin of New York University designed a test with “camouflage images” — photographs that had been systematically degraded. Volunteers had trouble identifying the images at first. But after the camouflage was switched with the original picture for a second, the subjects experienced an “Aha!” moment — the image now popped out clearly even in the degraded image.

Participants were then asked to repeat the exercise with dozens of different images. Later, they were given the camouflaged images to identify again, together with some they hadn’t seen before.

The team found that some of the memories disappeared over time, but the ones that made it past a week — about half — were likely to remain.

The initial viewing session was conducted in a functional MRI (fMRI) scanner. Looking at the results, the scientists discovered it was not only areas involved in object recognition that lit up in the scans in those who remembered the moment of insight. Also prominent was the amygdala, the brain’s emotion center.

“Our results demonstrate, for the first time, that the amygdala is important for creating long-term memories,” says Ludmer.