Elucidation of the mechanisms underway in the brain during sleep with a focus on the circuit mechanisms that promote memory formation

Abstract

Scientists have been unable to fully elucidate the mechanisms at work in the human brain during sleep. A particularly mysterious area is memory formation during sleep. Professor Masaki Takeda, Research Center for Brain Communication, the Kochi University of Technology, Japan, leads a team of researchers exploring brain behaviour and dynamism. A key focus is on human participants and what happens in their brains while sleeping, while a further element is looking at whether non-human primates have similar memory mechanisms to humans. A main goal for Takeda and the team is uncovering the causal role of neural activities during sleep in memory consolidation. As such, the researchers are attempting to noninvasively manipulate neural activity when human participants are sleeping and investigate how these manipulations affect memory performance after sleep. Using a combination of deep-learning decoding techniques and high spatiotemporal resolution of neural imaging by concurrent functional magnetic resonance imaging (fMRI) and electroencephalography (EEG), the team has developed a novel technique for detecting the replay activity that emerges as unstructured patterns of activations, overcoming challenges associated with the difference between spatial and semantic memory. In a recent project, Takeda and the team have been exploring brain circuit mechanisms during sleep that promote memory formation. The researchers are exploring whether the slow-oscillation neural activity during deep sleep (SO) in the frontal cortex during deep sleep has a causal role in memory consolidation in humans. This involves the manipulation of the phase of SOs using transcranial alternating current stimulation (tACS) whose phase is matched to that of SOs.