Brain may reveal your past

Scientists have found that human brain bears the imprints of earlier events for at least 24 hours after the experience has taken place.
This ability might reveal what makes each of us a unique individual, and it could enable the objective diagnosis of a wide range of neuropsychological diseases.
The new research by the Weizmann Institute in Israel stems from earlier findings in the lab of Professor Rafi Malach of the Institute's Neurobiology Department and others that the brain never rests, even when its owner is resting.
When a person is resting with closed eyes - that is, no visual stimulus is entering the brain - the normal bursts of nerve cell activity associated with incoming information are replaced by ultra-slow patterns of neuronal activity.

Such spontaneous or "resting" waves travel in a highly organised and reproducible manner through the brain's outer layer - the cortex - and the patterns they create are complex, yet periodic and symmetrical.
Like hieroglyphics, it seemed that these patterns might have some meaning, and research student Tal Harmelech, under the guidance of Malach and Dr Son Preminger, set out to uncover their significance.

Their idea was that the patterns of resting brain waves may constitute "archives" for earlier experiences. As we add new experiences, the activation of our brain's networks lead to long-term changes in the links between brain cells, a facility referred to as plasticity.

The researchers hypothesised that information about earlier experiences would thus be incorporated into the links between networks of nerve cells in the cortex, and these would show up in the brain's spontaneously emerging wave patterns.
In the experiment, the researchers had volunteers undertake a training exercise that would strongly activate a well-defined network of nerve cells in the frontal lobes.
While undergoing scans of their brain activity in the Institute's functional magnetic resonance imaging (fMRI) scanner, the subjects were asked to imagine a situation in which they had to make rapid decisions.
The subjects received auditory feedback in real time, based on the information obtained directly from their frontal lobe, which indicated the level of neuronal activity in the trained network.

This "neurofeedback" strategy proved highly successful in activating the frontal network - a part of the brain that is notoriously difficult to activate under controlled conditions.
Their findings, which appeared in the Journal of Neuroscience, showed that the activation of the specific areas in the cortex did indeed remodel the resting brain wave patterns.
Surprisingly, the new patterns not only remained the next day, they were significantly strengthened, researchers found.