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Electrically stimulating a nerve in the face has shown promise for boosting memory. Bursts of stimulation, delivered via skin electrodes, appear to improve signalling between cells in the hippocampus, a brain region crucial for memory. In a small study, this then enabled people to better remember what a group of strangers did for a living.聽

鈥淚f the benefits hold up, that could make [this stimulation] suitable for a wearable device and potentially accessible to many more people,鈥� says at The Feinstein Institutes in New York, who wasn鈥檛 involved in the study.

Electrical stimulation has been linked to improved memory before, but this is usually highly invasive or requires people to lie in a scanner. In 2024, at the Leuven Brain Institute in Belgium and his colleagues showed that a non-invasive technique, called transcranial direct current stimulation, sparks the trigeminal nerve 鈥� a three-part nerve in the head that carries sensory information between parts of the face and the brain. This then .

Now, the researchers have set out to understand whether this affects memory. They first established the best type of stimulation to apply, by delivering electrical stimulation to the trigeminal nerve of anaesthetised rats, via small electrodes under the skin.

They found that 1-second bursts of 200-hertz electrical stimulation, separated by 29 seconds of rest, increased signalling between hippocampal neurons by about 20 per cent. This continued for at least 90 minutes after the stimulation ended. In contrast, continuous stimulation at 100 hertz had no effect.

The researchers think intermittent stimulation specifically activates the locus coeruleus, a blue blob of neurons measuring just a few millimetres. This is the brain鈥檚 primary producer of noradrenaline, or norepinephrine 鈥� a chemical messenger that helps transmit nerve signals between neurons, and may also .

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When the researchers repeated the intermittent stimulation, but this time with the locus coeruleus chemically suppressed, they found there was no lasting increase in hippocampal activity.聽

Next, the researchers studied nine people with drug-resistant epilepsy who had electrodes implanted in their brains for routine monitoring. Skin electrodes around their jaw delivered the same pattern of 200-hertz stimulation to the trigeminal nerve for 20 minutes. This produced a similar electrical response in the hippocampus as that observed in the rats.聽

Finally, the researchers tested the effects of this on memory. Thirty-six adults with no known health conditions completed one session of bursts of stimulation, delivered via skin electrodes, and one sham session, at least two days apart. During these sessions, they were tasked with remembering the names and occupations that went with 12 faces, which they were tested on 2 minutes later. They then received bursts of stimulation for 20 minutes while they rested, before being tested on their memory again.

The stimulation improved occupation recall, but only at the 20-minute mark, which may be due to this resting period giving people time to consolidate what they had learned. The degree of improvement corresponds to 鈥渞oughly one extra association being retained鈥�, says McLaughlin.

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鈥淲hat impressed me was how the authors followed the question from synaptic changes in rats to direct recordings from the human hippocampus, then to memory testing in healthy volunteers,鈥� says Bahadir. 鈥淭hat is a substantial amount of work, and it makes the findings more convincing.鈥�

It鈥檚 unclear why there was an improvement only in occupation recall, and not names. McLaughlin suggests jobs like being a teacher bring to mind images of schools and classrooms, whereas someone鈥檚 name may be harder to remember if it has no personal connection to us.

The team is now comparing the effects of external electrical stimulation to the trigeminal nerve with that to the median nerve in the arm in up to 40 volunteers, which should reveal whether peripheral nerve stimulation may also be helpful.