S u m m a r y :
Electrical brain stimulation can boost memory in humans, an effect that can last until the next day, says a new study published in PNAS.
Stimulating the Brain of Epileptic Patients
Electrically stimulating a specific brain area has successfully boosted memory in epilepsy patients from Emory University Hospital. They were subjected to intracranial monitoring, an invasive intervention whereby electrodes were inserted into the brain to identify the origin of epileptic seizures. The research team, neuroscientists from Emory University, used this technique to perform direct electrical stimulation of the amygdala, the brain region associated with the regulation of memory and emotional behaviour, with the aim of enhancing memory, allowing the patients to better recognise certain images the day after.
“We were able to tag specific memories to be better remembered later,” says co-first author Cory Inman. “One day, this could be incorporated into a device aimed at helping patients with severe memory impairments, like those with traumatic brain injuries or mild cognitive impairment associated with various neurodegenerative diseases. However, right now, this is more of a scientific finding than a therapeutic one.”
Remembering Stimulated Images
The study participants initially viewed a group of 160 neutral objects on a screen, and they were to judge whether they belonged indoors or outdoors. For 50% of these images, the patients received stimulation 1 second after the disappearance of each image. They were then quizzed on half of the stimulated images, and half of the unstimulated ones immediately; the same was done the next day for the other half. Additionally, 40 new images were shown to them.
The findings show that the stimulation did not bring immediate recognition, but the effects thereof were clear during the image viewing the following day. According to the findings, 79% of the patients had a better performance on overnight memory tests.
“This makes sense because the amygdala is thought to be important for memory consolidation—making sure important events stick over time,” says co-first author, Joseph Manns.
Specially Beneficial For Those With Poor Memory
It is to be noted that patients who had a greater memory boost were those with a generally poorer memory performance. Those with average memory also had theirs improved, though.