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Nerve cells in the brain highly active during anesthesia
One might assume that the brain stops working under general anesthesia, but researchers have now found that nerve cells in the cerebral cortex are also highly active during deep anesthesia. However, they change their working mode.
Nerve cells in the brain remain active
In a study, scientists from the Berlin University Hospital Charité were able to show that nerve cells in the brain remain in action even during deep anesthesia, even though consciousness is completely switched off. However, they change their working mode. As the researchers report in the journal "Frontiers in Cellular Neuroscience", the neurons work synchronously under anesthesia and react unexpectedly sensitively to environmental stimuli.
How awareness is produced
According to a Charité communication, the scientists wanted to get closer to the answer to the question of how the brain produces consciousness. For this, a team led by Dr. Mazahir T. Hasan of the Charité together with colleagues at the Max Planck Institute for Medical Research Heidelberg compared the brain activity of mice when awake, conscious and under anesthesia.
The respective activity of the nerve cells was visualized. Dr. Hasan explained: “We used a fluorescent protein that converts electrical signals into light signals. The number and the average level of the discharges as well as the synchronicity of the nerve cells in the network could thus be shown. "
According to the results, consciousness in the brain does not seem to depend simply on the number of active nerve cells in the cortex (cerebral cortex), but rather on the subtleties of how they communicate with one another and to what extent they can contrast their behavior with one another.
Brain changes the way we work
While the nerve cells of the cortex light up in complex patterns at different times when awake, it can be observed under anesthesia that they are all active simultaneously and in the same way.
“Contrary to the plausible assumption that the brain stops being active under anesthesia, it only changes the way we work. According to our study, the strength of the nerve cell discharges does not change, ”says the first author of the study, Thomas Lissek, neurobiologist in Heidelberg.
More sensitive under anesthesia than when awake
It is also unexpected to observe that nerve cells react more sensitively to stimuli from the environment under anesthesia than when awake. "A surprising observation, since anesthesia is used in particular to reduce pain and environmental stimuli during an operation," said Lissek. According to the information, a region of the brain that is normally responsible for tactile information even started to respond to acoustic stimuli.
As the message says, the new insights into the activity patterns of the neurons provide clues as to which cellular parameters are associated with consciousness and loss of consciousness. Together with further advances, they could improve diagnostics, for example in coma patients or patients with locked-in syndrome.
The current study demonstrates for the first time that it is possible to observe visually identifiable neural networks over a period of several weeks in order to further investigate the effects of anesthesia. "We believe that anesthesia research will bring deep insights to human consciousness," said Dr. Hasan. (ad)