Groundbreaking research recently published in Nature Neuroscience has shed light on the intricate workings of the human brain, specifically regarding how long-term memories are consolidated during sleep. The study found that a deep connection exists between the hippocampus and the cerebral cortex during our sleep cycles, which plays a vital role in the formation of lasting memories. Interestingly, the scientists discovered that deep-brain stimulation while sleeping can significantly enhance this process of memory consolidation.
The pioneering research project was led by Dr. Maya Geva-Sagiv, currently at UC Davis, and represents a collaborative effort of several leading laboratories including those of Prof. Yuval Nir at Tel Aviv University’s Sackler Faculty of Medicine, Department of Biomedical Engineering, and Sagol School of Neuroscience, and Prof. Itzhak Fried at UCLA’s Department of Neurosurgery and the Sackler Faculty of Medicine at Tel Aviv University.
The study was made feasible thanks to a group of 18 epilepsy patients at the UCLA Medical Center. These patients had electrodes implanted in their brains by Prof. Fried, in an attempt to isolate the origin of their epileptic seizures. These individuals agreed to participate in an investigation into the effects of deep-brain stimulation during sleep.
“Our research provided the opportunity to assess for the first time in humans the long-held theory that the synchronised activity of the hippocampus and cerebral cortex during sleep plays a key role in memory consolidation,” says Prof. Nir. “In fact, we not only validated this theory but also found that memory consolidation could be enhanced via a unique stimulation protocol that increased synchronisation between these two brain areas. This represents an innovative approach that may offer future solutions for individuals suffering from memory impairments such as dementia.”
The main focus of the research was to bolster the natural mechanisms that take place during sleep to help understand how sleep aids in cementing memories. The team of researchers created a deep-brain stimulation system that boosts electrical communication between the hippocampus and the frontal cortex. By observing hippocampus activity during sleep, the system could deliver accurately timed electrical stimulation to the frontal cortex.
After conducting two memory tests where participants were asked to recognize images of famous personalities they were shown the previous night, the study found that deep-brain stimulation greatly improved the precision of their memory. Interestingly, the researchers found that the intervention did not significantly increase the number of correct responses but rather reduced the number of incorrect ones.
“This indicates that sleep sharpens the precision of our memory by eliminating various distractions from the relevant memory trace,” adds Prof. Nir. This fascinating research thus opens the door to potential future advancements in memory enhancement and treatment for memory impairments.
