There is new scientific evidence to support the time-honored advice to students cramming for exams to get themselves a good night’s sleep after studying. Researchers who analyzed brain activity in sleeping volunteers who had learned to navigate through a computer-generated virtual town have discovered evidence that spatial memories are consolidated during deep sleep.
Also, the researchers say that they have shown for the first time that the activity level in the brain’s learning center, the hippocampus, correlates with the improvement in memory performance when the subjects are tested the next day. According to Philippe Peigneux and his colleagues, "A growing body of experimental evidence shows the influence of sleep on the consolidation of recent memory traces. The underlying hypothesis posits that the information that is acquired during wakefulness is actively altered, restructured, and strengthened during sleep."
However, they said, exploring this consolidation process was difficult because of the complexities of both sleep and memory. For example, sleep consists of two major stages -- rapid eye movement (REM) sleep and non rapid eye movement (NREM) sleep. Evidence from animal studies of learning and sleep indicated that spatial memories seem to be replayed in the hippocampus during the deep "slow wave sleep" (SWS) during the NREM sleep stage.
The researchers measured the subjects’ brain activity using positron emission tomography (PET) to measure blood flow in the subjects’ brain regions. In PET, test subjects receive a harmless dose of radioactive tracer, and their brains are scanned as the tracer infuses through the brain. Blood flow through specific brain structures constitutes a measure of activity in that structure.
The researchers found that the first group -- compared to the non-trained group -- showed greater activity in their hippocampus and an adjacent learning-related region as they took the route tests, with greater activity correlated with better performance. The group scanned during sleep after testing also showed greater hippocampal brain activity during sleep, compared to the non-trained group. Importantly, when the researchers compared the hippocampal activity during SWS sleep in the trained group and the non-trained group, they found that the first group showed higher activity.
Next, the researchers tested the trained group after their sleep session and compared their performance with the brain activity measured during sleep. They found that the higher the gain in post-sleep performance, the higher had been their NREM brain activity during sleep. No such correlation was found in REM brain activity.
To ensure that they were, indeed, measuring brain activity due to spatial processing, Peigneux and his colleagues also compared brain activity data from the spatially trained group with data from a fourth group that had only taken a reaction time test. In that test, the subjects’ brains were scanned as they pressed a key as fast and accurately as possible corresponding to the location of a dot on a computer screen.
Thus, the data from the fourth group allowed the researchers to distinguish brain activity changes due to spatial processing from those due to general mental processing. The researchers’ comparisons of the brain activity in the groups confirmed that the hippocampal activity they detected was due to spatial processing.
"Our results provide critical evidence that spatial memory traces are processed during NREM sleep in humans," wrote the scientists. "Moreover, the hippocampal activity during sleep is shown to correlate with the improvement in memory performance on the next day. To the extent of our knowledge, this effect has not yet been reported in the animal hippocampus."
Heidi Hardman | EurekAlert!
WAKE-UP provides new treatment option for stroke patients | International study led by UKE
17.05.2018 | Universitätsklinikum Hamburg-Eppendorf
First form of therapy for childhood dementia CLN2 developed
25.04.2018 | Universitätsklinikum Hamburg-Eppendorf
So-called quantum many-body scars allow quantum systems to stay out of equilibrium much longer, explaining experiment | Study published in Nature Physics
Recently, researchers from Harvard and MIT succeeded in trapping a record 53 atoms and individually controlling their quantum state, realizing what is called a...
The historic first detection of gravitational waves from colliding black holes far outside our galaxy opened a new window to understanding the universe. A...
A team led by Austrian experimental physicist Rainer Blatt has succeeded in characterizing the quantum entanglement of two spatially separated atoms by observing their light emission. This fundamental demonstration could lead to the development of highly sensitive optical gradiometers for the precise measurement of the gravitational field or the earth's magnetic field.
The age of quantum technology has long been heralded. Decades of research into the quantum world have led to the development of methods that make it possible...
Cardiovascular tissue engineering aims to treat heart disease with prostheses that grow and regenerate. Now, researchers from the University of Zurich, the Technical University Eindhoven and the Charité Berlin have successfully implanted regenerative heart valves, designed with the aid of computer simulations, into sheep for the first time.
Producing living tissue or organs based on human cells is one of the main research fields in regenerative medicine. Tissue engineering, which involves growing...
A team of scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg investigated optically-induced superconductivity in the alkali-doped fulleride K3C60under high external pressures. This study allowed, on one hand, to uniquely assess the nature of the transient state as a superconducting phase. In addition, it unveiled the possibility to induce superconductivity in K3C60 at temperatures far above the -170 degrees Celsius hypothesized previously, and rather all the way to room temperature. The paper by Cantaluppi et al has been published in Nature Physics.
Unlike ordinary metals, superconductors have the unique capability of transporting electrical currents without any loss. Nowadays, their technological...
02.05.2018 | Event News
13.04.2018 | Event News
12.04.2018 | Event News
18.05.2018 | Power and Electrical Engineering
18.05.2018 | Information Technology
18.05.2018 | Information Technology