Researchers from Tel Aviv University recorded the eye movements during sleep of epilepsy patients who were about to undergo surgery * The research was published tonight (11.8.15) in the journal Nature
Communications
Already in the 50s of the last century, scientists discovered the 'dream sleep' or REM sleep (Rapid Eye Movement) - a phase of sleep characterized by colorful dreams and rapid eye movements. But only now, some 60 years later, have researchers from Tel Aviv University succeeded in scientifically proving the - seemingly intuitive - connection between eye movements and the 'movies' we see in a dream.
The research was carried out by Dr. Yuval Nir from the Department of Physiology and Pharmacology at the Faculty of Medicine and the Segol School of Brain Research at Tel Aviv University, who led the research in collaboration with Prof. Yitzhak Fried - a world-renowned brain surgeon from the University's Faculty of Medicine and the UCLA Medical Center in Los Angeles , and the director of the functional neurosurgery unit at the Tel Aviv Medical Center (Ichilov). Also participating in the study were: Thomas Andrion from Paris, as well as Dr. Giulio Tononi and Dr. Chiara Cirelli from the University of Wisconsin in Madison. The research will be published tonight (Tuesday 11.8.15) in the journal Nature Communications.
For the purpose of the groundbreaking study, the researchers relied on a one-of-a-kind database, which comes from the world of medicine, or more precisely - brain surgeries on epilepsy patients: "Sometimes when an epilepsy patient does not respond to drug treatment, the doctors try to find the focus in his brain that causes the seizures, and help him through surgery, during which the focus was cut. In preparation for surgery, sensors are implanted inside the patients' brains, and the brain activity is monitored in this way for about 10 days," explains Dr. Yuval Nir. "This is how a rare collection of data was created - which cannot be obtained in any other way - data taken straight from the depths of the human brain. We used this data to find out what happens in the brain during the 'dream year'."
Like changing slides
19 volunteers participated in the unique study - all epilepsy patients under the care of Prof. Fried, in the Department of Neurosurgery at the UCLA Medical Center. "We asked them for permission to use the medical procedure they went through anyway for the purpose of our scientific research, and they willingly responded," says Dr. Nir. "Consequently, we recorded their brain activity even while sleeping, and attached stickers to their eyes that recorded the eye movements - for the purpose of matching with the activity detected in the brain."
In addition, the researchers presented the participants with images of familiar places and people - such as the Eiffel Tower, famous people or family members - in order to accurately locate the neurons that wake up when the brain recognizes an image, and remembers the associated associations. In the studies he conducted in the past, Prof. Fried discovered that even when a person closes his eyes and imagines, an active activity is registered in those cells - similar to what happens in the brain when seeing real objects.
"We wanted to check what happens in these cells - which are responsible for recognizing images and encoding concepts in the brain - during the 'dream year,'" says Dr. Nir. "Analysis of the data we collected revealed a fascinating correspondence between eye movement and brain activity: every time the eyes moved, many neurons associated with image recognition woke up about 0.3 second later. Moreover: the characteristics and indices
of the burst of brain activity - for example, the order of awakening and the time intervals - were exactly similar to those familiar to us from the actions of viewing an actual image or conjuring up an image in the imagination. In fact, it seems as if every time the eyes move, a 'reflection' is replaced by a 'film' of the dream."
And so, for the first time, after more than 60 years of hypotheses and experiments, the connection between the rapid eye movements during dream sleep and specific brain activity of representing images and memories was scientifically proven.
The new research is another step towards deciphering the role of dreams in sleep and in life in general. "Studies from recent years have proven that during sleep, processes occur in the brain that help refresh and reorganize memories." says Dr. Nir. "In our laboratory we study the functioning of the brain in different states of consciousness - during waking hours, in full anesthesia, during loss of consciousness, during fatigue, and of course also during sleep. At the same time as other research methods, we use the rare data obtained from the depths of the human brain, with the help of Prof. Fried and his patients."
2 תגובות
So babies also see and reproduce it in a dream? and blind?
Or for them the movement of the eyes in sleep imitates the physical activity while awake, but is linked and reproduces other sensations (hearing, touch, smell, etc.)
"Every time the eyes moved, many neurons associated with image recognition woke up about 0.3 second later." It is interesting that the physical activity of the eyes precedes the images. It is likely that the physical activity was preceded by another process of (abstract) thinking represented by electrical activity in another part of the brain, which also leads to the physical activity. Another question in this context: when does the dreamer become 'aware' of his dream - is it simultaneous with the aforementioned mental activity, or is it delayed.