The amygdala is the region of the brain responsible for making us feel emotions. This zone, in addition, allows to regulate the memory. In fact, it has been shown that events that are accompanied by an emotional stimulus persist in the brain for longer than neutral events.
Based on this premise, the challenge that has been posed by a team of neuroscientists has been to subject the human amygdala to electrical impulses to improve memory systems without the need to link it to emotions. The study has shown how the amygdala can modulate the processes of memory consolidation in other regions of the brain, such as the hippocampus and the perirhinal cortex.
The experiment has been carried out at Emory University Hospital, in Atlanta (USA). The aim was to reinforce in patients the memory of images that had been shown a day before.
Fourteen patients with epilepsy underwent intracranial monitoring, an invasive procedure used to diagnose the origin of the brain impulses, during which electrodes are introduced into the subject’s brain.
They all observed a series of photographs of neutral objects, 160 in all. For half of these images, the participants received electrical stimulation for one second after each image disappeared from the screen.
The effect of the stimulation on immediate recognition was not statistically significant and neither did it provoke a subjective emotional response. However, the next day, the effects on the stimulated images were clear. An improvement in memory had been caused.
“We chose the amygdala after decades of research in rodents, proving that it modulates memory structures,” says one of the authors Joseph Manns, associate professor of psychology. “We wanted to stimulate their endogenous function, which we believe is a sign of prominence, something outstanding, to remember specific experiences in the future,” he says.
Results of the finding
This discovery is the first example of electrical stimulation of the brain in humans.
The results show that 79% of the participants (that is, 11 of the 14 total participants) showed an improvement in memory tests during the night, while the remaining 21% did not show any improvement or deterioration.