Image: Rolands Lakis
The realm of sleep and dreams has long been associated with strangeness: omens or symbols, unconscious impulses and fears.
But this sometimes disturbing world of inner turmoil, fears and desires is grounded in our day-to-day experience, sleep researchers say.
"The structure and content of thinking looks very much like the structure and content of dreaming. They may be the product of the same machine," said Matthew Wilson, a neuroscientist at MIT and a panelist at the New York Academy of Sciences discussion "The Strange Science of Sleep and Dreams" on Friday (Nov. 9).
His work and others' explores the crucial link between dreams and learning and memory.
Dreams allow the brain to work through its conscious experiences. During them, the brain appears to apply the same neurological machinery used during the day to examine the past, the future and other aspects of a person's (or animal's) inner world at night. Memory is the manifestation of this inner world, Wilson said.
"What we remember is the result of dreams rather than the other way around," he said.
Dreams as teachers
His work, and that of fellow panelist Erin Wamsley, a sleep scientist at Beth Israel Medical Center/Harvard Medical School, focuses on the relationship between memory and dreams in non-REM sleep. Vivid dreams often occur during REM sleep, named for the rapid eye movement associated with it, however, non-REM sleep also brings dreams but they are more fragmentary.
Wamsley's research indicates dreams help people learn. [7 Mind-Bending Facts About Dreams]
In a study published in the journal Current Biology in April 2010, she and colleagues found that study subjects who entered non-REM sleep and dreamed about a video game maze they had played hours earlier saw their performance increase dramatically more than those who slept but did not report any maze-related dreams. Meanwhile, thinking about the maze while awake did not improve the players' performance.
Although this work focused on non-REM sleep, incorporation of learning happens in all stages of sleep, Wamsley told the audience.
Wamsley has also used another video game, this one of a downhill skiing, to probe the relationship between dreams and learning. Like the maze, this game was intended to be interactive and exciting for the subjects, Wamsley said.
Subjects reported their dreams after playing, and initially, their dreams put them directly back into the game, as if rehearsing. But as they fell deeper into sleep, their dreams became more extractive with less literal relationship to the game, she said. For instance, one subject described following boot prints in the snow.
This may be because in deeper sleep, the brain is trying to extract meaning from the experience earlier in the day. The subject's dream about boot prints may have been a way to refine the dreamer's concept of how to move through snow, she said.
Learning the maze
Like some of Wamsley's subjects, Wilson's also dreamed of mazes, but these mazes were real.
By accident, Wilson found when rats fall asleep their brains replay parts of their experience in a maze. By using fine electrodes to eavesdrop on the activity of single neurons in the hippocampus, a region of the brain associated with spatial memory, he saw this happen.
Individual neurons in rats' and humans' hippocampuses fire in response to spatial location, so each time a rat passes a certain point within the maze a single neuron fires. Once the rats fell asleep, Wilson found these neurons would fire as they were reactivated in patterns that represented brief segments of the maze, which could be run forward or in reverse, Wilson found.
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5 Comments
Add CommentSo according to paragraph three, Schizophrenic patients answered the test more accurately than their healthy neighbors because they did not incorporate false assumptions of tone thus responding to the test later.... so define healthy again.....
Reply | Report Abuse | Link to thisThere's a potential functional explanation for much of what we experience during dreaming. We know that we have both short term and long term memories.
Reply | Report Abuse | Link to thisIn computer systems, this separation allows the very efficient, high speed storage of information acquired during periods of 'normal' operations (i.e., commonly, during the day). In order to minimize the impact of data acquisition to competing processes and potential data loss, new information is simply stored in a 'temporary' high speed buffer as a sequential list, analogous to short term memory.
In order to clear this limited high speed memory for reuse and complete the processing of the newly acquired information, further analyzing it to minimize long term storage requirements and maximize its retrieval flexibility and information value, it is retrieved during 'off-hours' or 'downtime', analogous to sleep, when competing processes are either not very active or, more conveniently, can be quiesced or shut down.
This better utilizes available processing capacity and allows processes that could interfere with normal operations, such as making structural modifications to critical memory elements.
During this 'database maintenance' processing, newly acquired information elements are retrieved and their content in analyzed in the context of preexisting information. This usually requires the retrieval of segments or 'snippets' of long term memories so that the new information can be linked or in other ways related to existing information, potentially optimizing later retrieval performance for perhaps many varying uses, likely eliminating potentially redundant information (the image of your dog, for example) or replacing with external references or links. In this way every dog experience in long term memory does not contain a large, high resolution image of a dog. Maintaining separate indexes - linked lists, can allow fast retrieval of all dog memories, for example.
So, in this way the offline background tasks related to the optimization long term memory database storage space usage, access speed and information content can require the retrieval (and perhaps reexperience) of past memories. Short term memories of information deemed to be unnecessary can be discarded. When all the high speed, short term 'bulk' memory has been processed, its high speed storage can be cleared for reuse the following day.
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Reply | Report Abuse | Link to thisThe past and newly acquired information retrieved and analyzed during the database maintenance process might produce some residual reexperiences, or dream recollections. Perhaps, if we routinely experience 'bad' dreams of falling, spiders, being lost, etc., it is because the identification of those experiences has been prioritized for some reason, resulting in all new information being evaluated in those contexts.
Of course, there may be other factors contributing to our dream state recollections, but having the ability to acquire new information during 'normal operations' while minimizing the impact to processes critical to those operations essentially dictates the necessity for some off-hour or offline memory maintenance processes, to free up short term memory capacity consumed during the day.
BTW, a well known if extreme example of such information systems is the CERN Large Hadron Collider data acquistion systems. Experiment detector facilities capture the detections of residual particles produces by high energy particle accelerated. The very large amount of data collected during each collision is 'dumped' to disk subsystems and later processed offline to search for interesting conditions represented by the combinations of various particles detected. That information is further analyzed by scientists - the potential Higgs boson 'discovery' was inferred from the presence of a couple of intriguing photons...
Reply | Report Abuse | Link to thisAs always, I'm disappointed.
Reply | Report Abuse | Link to thisWould it be so difficult to use dreams in their best form, ie: what we see in dreams are symbols which tell a story of what lies ahead.
Going Up via ladder, elevator or climbing stairs denotes future success.
Going Down, the lack thereof.
Houses and cars represent us, so if we run out of gas in a dream, we run out of energy in "real life."
The Moon - something hidden revealed/The Sun - Happiness.
But what of great inventors who took naps and awoke having the answer in mind derived from a dream?
The problem it seems is modern day science doesn't seem to address what some knew in ancient Egypt and it does beg one to wont to sing, "When will they ever learn, long time passing?"