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The technique could potentially bolster memories while asleep and assist in rehabilitation therapy after trauma or stroke.

By United with Israel Staff

A joint study by researchers at Tel Aviv University (TAU) and the Weizmann Institute of Science found an innovative method for bolstering memory during sleep – through smell.

They found that scent administered to one nostril during sleep evokes memory. The discovery could potentially help restore memory to those with brain injuries, post-traumatic stress disorder (PSTD) or stroke. The findings were published recently in Current Biology.

“By triggering consolidation processes in only one side of the brain during sleep, we were able to compare the activity between the hemispheres and isolate the specific activity that corresponds to memory reactivation,” TAU Prof. Yuval Nir, a reasearcher in the team, explained.

The scientists exposed participants to a rose scent while asking them to remember the location of words presented on either the right or the left side of a computer screen. They were then tested on the location of the words.

After the initial test, they took a nap in the lab. While sleeping, they were again exposed to the rose scent, but only through one nostril.

Knowing that memories stored in the left brain hemisphere are associated with locations on the right side of a person and visa versa, the finding corroborated that specific memories can be reactivated in specific brain hemispheres through smell.

“We know that a memory consolidation process takes place in the brain during sleep,” Bar said. “The technique we developed could potentially influence this aspect of the memory during sleep and decrease the emotional stress that accompanies recall of the traumatic memory. Additionally, this method could be further developed to assist in rehabilitation therapy after one-sided brain damage due to stroke.”

They also found that EEGs taken while participants slept showed electrical brain wave activity was improved in the hemisphere triggered by the rose scent.

More impressively, a second memory test given upon waking showed that the words were better retained on the side affected by the smell.

“Beyond promoting basic scientific understanding, we hope that in the future this method may also have clinical applications,” Bar said. “For instance, post-traumatic patients show higher activity in the right hemisphere when recalling a trauma, possibly related to its emotional content.”

“Our findings emphasize that the memory consolidation process can be amplified by external cues such as scents. By using the special organization of the olfactory pathways, memories can be manipulated in a local manner on one side of the brain,” Bar concluded.