Don't try this at home

Here’s something straight out of a sub-Frankenstein story. By passing a mild electrical current through the brain, you can improve memory, at least for words.

Scientists have discovered a surprising way of improving memory: passing electricity through the brain while you are asleep. They have found that mild electrical stimulation at the right frequency improved people's ability to remember words on waking up.

Jan Born, a neuroscientist at the University of Lübeck in Germany who led the research, said the electrical current, applied via electrodes stuck to the scalp, seemed to enhance a part of the sleep cycle linked to consolidating word memory. Dr Born had 13 medical students learn a list of words and tested how many they remembered after a set time. He had them repeat the exercise after a nap.

The results, published today in Nature, show that without electrical current the volunteers remembered, on average, 37.42 words before sleep and 39.5 words when they woke. It confirmed research that sleep is important for consolidating learned information. After electrical stimulation the number of words volunteers remembered rose to 41.27 after sleep.

The researchers think their electrical stimulation enhanced the early part of the volunteers' sleep cycle called "slow wave sleep". During slow wave sleep there are regular electrical fluctuations in the prefrontal neocortex, which is linked to conscious thought and spatial reasoning.

In his experiment Dr Born's electrical current was tuned to match these natural fluctuations. When current was applied at a different frequency or during a different part of the sleep cycle there was no memory boost. How the electrical fluctuations in the brain lead to consolidation of memory is unclear.

One plausible theory, according to Dr Born, is that electrical currents of a particular frequency can make brain cells resonate. This strengthens connections between networks of cells, which are the physical representations of memories in the brain.

Guardian story here. An interesting note Dr Born made in the Nature paper: “This improvement in retention following stimulation is striking considering that most subjects were medical students, who were highly trained in memorising facts and already performed well in the sham condition.”