Gentle electric currents stimulate the brain and boost the memory

German scientists say they have found that gentle electric currents which stimulate the brain while sleeping can boost the memory.

The scientists at the University of Lubeck say that when several mild electrical stimulation at the right frequency was applied to patients brains while they were sleeping, their ability to remember words on waking improved.

The currents, applied via electrodes stuck to the scalp, apparently mimic the natural slow oscillating brain waves in the sleep cycle linked to consolidating word memory.

During slow wave sleep there are regular electrical fluctuations in the prefrontal neocortex, which is linked to conscious thought and spatial reasoning.

The experiment which was carried out on thirteen medical students who had done a word-learning task, led to improved memory retention, says lead author neuroscientist Jan Born.

The scientists suggest brain stimulation could help people with memory problems and Alzheimer's disease and offers an alternative method of intensifying or improving sleep and its memory function.

The researchers stimulated their brain while they slept and on awaking the students were asked to recall the words they had memorized.

The scientists found that if the currents were applied to the scalp during the deep sleep phase, during the first few hours of nocturnal sleep, the students recalled a greater number of words than if they had been given a sham brain stimulation.

Born says the eight percent increase overall was striking and shows that slow oscillation has the function during sleep of building and consolidating memory.

During the procedure the medical students, who already had good memory function, did not feel any sensation from the currents to the frontal cortex of the brain or suffered any adverse side effects.

According to the team, the currents forced the brain more into the deep slow-wave sleep to improve the memory function.

Born says there is growing evidence that brain function can be very effectively manipulated by different types of electrical simulation.

He believes the natural slow oscillations and those induced by the electrical currents affect the hippocampus area of the brain which plays a part in memory by triggering almost a replay of memories in the hippocampus.

One of the first regions of the brain that is damaged in patients with the degenerative illness Alzheimer's disease, is the hippocampus and victims are robbed of their memory and cognitive ability.

The study is published in the journal Nature.