The amygdala is the region of the brain responsible for making us feel emotions . This area also allows you to regulate memory . In fact, events that are accompanied by an emotional stimulus have been shown to persist in the brain for longer than neutral events.
Starting from this premise, the challenge 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 memory consolidation processes in other brain regions, such as the hippocampus and the perirrinal cortex.
The experiment was carried out at Emory University Hospital in Atlanta (USA). The objective was to reinforce in the patients the memory of some images that had been shown to them the day before.
Fourteen patients with epilepsy underwent intracranial monitoring, an invasive procedure used to diagnose the origin of brain impulses, during which electrodes are inserted into the subject’s brain.
They all looked at 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 stimulation on immediate recognition was not statistically significant, nor did it elicit a subjective emotional response. However, the next day , the effects on the stimulated images were clear. Memory had been improved .
“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 its endogenous function, which we believe is a sign of prominence, something outstanding, to remember specific experiences in the future,” he says.
Finding results
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.
Therefore, it is understood that the amygdala can initiate endogenous memory prioritization processes (which is formed by internal causes) in the absence of an extra emotional contribution . According to the scientists, this addresses a fundamental question and opens the way to future therapies.
“We want to better understand the brain’s endogenous mechanisms for memory modulation before moving forward with a device,” says Manns.
The University of Atlanta team is now focused on adjusting the parameters of amygdala stimulation to continue to advance memory optimization. For this reason, other types of memory tests are being considered, such as spatial or verbal tasks, as well as tasks that more closely mimic memory for real-world events.
References:
‘Direct electrical stimulation of the amygdala enhances declarative memory in humans’. Cory S. Inmana, 1, Joseph R. Mannsb, 1, Kelly R. Bijankia, David I. Bassc, Stephan Hamannb, Daniel L. Draned, Rebecca E. Fasanod, Christopher K. Kovache, Robert E. Grossa and Jon T. Williea. Edited by Daniel L. Schacter, Harvard University, Cambridge. (2017). PNAS. D oi: 10.1073 / pnas.1714058114
