Matthew A. Wilson, professor of brain and cognitive sciences at MIT's Picower Institute for Learning and Memory, and postdoctoral associate Daoyun Ji looked at what happens in rats' brains when they dream about the mazes they ran while they were awake.
In a landmark 2001 study, Wilson showed that rats formed complex memories for sequences of events experienced while they were awake, and that these memories were replayed while they slept-perhaps reflecting the animal equivalent of dreaming.
Because these replayed memories were detected in the hippocampus, the memory center of the brain, the researchers were not able to determine whether they were accompanied by the type of sensory experience that we associate with dreams-in particular, the presence of visual imagery.
In the latest experiment, by recording brain activity simultaneously in the hippocampus and the visual cortex, Wilson and Ji demonstrated that replayed memories did, in fact, contain the visual images that were present during the running experience.
"This work brings us closer to an understanding of the nature of animal dreams and gives us important clues as to the role of sleep in processing memories of our past experiences," Wilson said.
By recording the spiking patterns of electrodes in individual neurons in the rats' brains, Wilson is able to compare the activity of the neurons when the animal is awake and asleep. It turns out that neurons activated when the animal experiences an event while awake are reactivated during sleep.
In addition, the region of the cortex that processes input from the senses and the hippocampus "talk" to each other during sleep, leading researchers to speculate that this process reinforces and consolidates memories.
But research to date lacked specific evidence that episodic memory-times, places and emotions related to events that make up our life stories-is reinforced in the cortex, the hippocampus or both during sleep.
For the first time, this work shows that the brain is replaying memory events in two locations at once-in the visual cortex and in the hippocampus.
"These results imply simultaneous reactivation of coherent memory traces in the cortex and hippocampus during sleep that may contribute to or reflect the result of the memory consolidation process," Wilson and Ji wrote.
This work is supported by the Brain Science Institute at the Institute of Physical and Chemical Research (RIKEN) in Japan and the National Institutes of Health.
Elizabeth A. Thomson | MIT News Office
Multi-institutional collaboration uncovers how molecular machines assemble
02.12.2016 | Salk Institute
Fertilized egg cells trigger and monitor loss of sperm’s epigenetic memory
02.12.2016 | IMBA - Institut für Molekulare Biotechnologie der Österreichischen Akademie der Wissenschaften GmbH
A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.
Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...
In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.
“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...
The Max Planck Institute for Physics (MPP) is opening up a new research field. A workshop from November 21 - 22, 2016 will mark the start of activities for an innovative axion experiment. Axions are still only purely hypothetical particles. Their detection could solve two fundamental problems in particle physics: What dark matter consists of and why it has not yet been possible to directly observe a CP violation for the strong interaction.
The “MADMAX” project is the MPP’s commitment to axion research. Axions are so far only a theoretical prediction and are difficult to detect: on the one hand,...
Broadband rotational spectroscopy unravels structural reshaping of isolated molecules in the gas phase to accommodate water
In two recent publications in the Journal of Chemical Physics and in the Journal of Physical Chemistry Letters, researchers around Melanie Schnell from the Max...
The efficiency of power electronic systems is not solely dependent on electrical efficiency but also on weight, for example, in mobile systems. When the weight of relevant components and devices in airplanes, for instance, is reduced, fuel savings can be achieved and correspondingly greenhouse gas emissions decreased. New materials and components based on gallium nitride (GaN) can help to reduce weight and increase the efficiency. With these new materials, power electronic switches can be operated at higher switching frequency, resulting in higher power density and lower material costs.
Researchers at the Fraunhofer Institute for Solar Energy Systems ISE together with partners have investigated how these materials can be used to make power...
16.11.2016 | Event News
01.11.2016 | Event News
14.10.2016 | Event News
02.12.2016 | Medical Engineering
02.12.2016 | Agricultural and Forestry Science
02.12.2016 | Physics and Astronomy