morphine and dexmedetomidine both act through different molecular mechanisms in a way that effectively causes sleep when they disrupt mental wave stage alignment. A new research reveals that these anesthetics cause a typical name: local cerebral communication is hampered by increased phase locking at lower frequencies, especially between brain hemispheres.
This suggests that step alignment, rather than just brain storm power, may be a common indicator of sleep. Researchers believe that monitoring period shifts was aid anesthesiologists in better tailoring drug dosage in real time, regardless of the type of drug being used.
Important Information:
- Universal Signature: Related brain wave period shifts that are related to unconsciousness are both produced by ketamine and dexmedetomidine.
- Stage Locking: Achieving greater interhemispheric phase alignment and a nearby phase coherence that is compromised may show a loss of consciousness.
- Clinical Potential: Monitoring brain wave stage may help with real-time anesthesia monitoring and dosage.
Origin: MIT Picower Institute
Ketone and dexmedetomidine work quite differently at the level of substances and cells, but in the operating room they do the same thing: anesthetize the person.
A fresh study by researchers at The Picower Institute for Learning and Memory at MIT shows how these different medications produce the same outcomes. It suggests a possible name of sleep that is easily quantifiable in an anesthesia treatment.
The scientists discovered that the two medications work together by generating brain waves, which are generated by the brain’s social electronic exercise.
Local groups of neurons in the body’s brain may communicate information to make informed cognitive functions like notice, perception, and reasoning when brain waves are in phase, which means that the peaks and valleys of the waves are aligned.
Local communications, and thus functions, fall apart when brain waves go out of phase, leading to unconsciousness.
The study, led by graduate student Alexandra Bardon, could provide a common new measure for anesthesiologists who use a variety of different anesthetics to keep patients on the right side of that line during surgery, Miller said. It also improves scientists ‘ understanding of the dividing line between consciousness and unconsciousness.
You can hardly tell what drug it was if you examine the way the phase shifts in our recordings, Miller, a professor at the Picower Institute and MIT’s Department of Brain and Cognitive Sciences, said.
That is beneficial for medical practice. Additionally, if unconsciousness has a universal signature, it might also reveal the mechanisms that create consciousness.
Anesthesiologists might be able to use brain wave phase alignment as a reliable indicator of unconsciousness as they titrate doses of anesthetic drugs, Miller said, regardless of which particular combination of drugs they are using, if additional anesthetic drugs are also shown to affect phase in the same way.
That understanding could aid efforts to create closed-loop systems that can continuously adjust the dosage of medications based on brain wave data from unconscious patients.
In order to create a system like this, Miller has been working with study co-author Emery N. Brown, an anesthesiologist and Edward Hood Taplin Professor of Computational Neuroscience and Medical Engineering at The Picower Institute.
Brown and colleagues in Japan conducted a , a recent clinical trial, and it demonstrated that using EEG to monitor brain wave power signals made it possible for an anesthesiologist to use significantly less sevoflurane during surgery with young children.
The reduced doses were effective, and they were linked to many improved clinical outcomes, including a lower post-operative delirium risk.
findings of the phase
Although anesthesia has not been a topic of conversation in recent years, Bardon, Brown and Miller’s team made a point of it by anesthetizing two animals.
The measurements showed a significant increase in “phase locking,” especially at low frequencies, after the animals lost consciousness. The relative differences in phase are more stable because of phase locking.
However, what caught the researchers ‘ attention were the differences that became ingrained: regardless of the anesthetic they used, the brain wave phase changed from the dorsolateral to the ventrolateral regions of the prefrontal cortex.
Surprisingly, the brain wave phase across the hemispheres increased rather than decreased. However, Miller points out that there is still a significant shift from the conscious state, where brain hemispheres are typically not aligned well, so Miller’s finding is another indication that significant phase alignment changes, albeit in different ways and at different distances, are a factor in unconsciousness versus wakefulness.
The Bardon and Miller team wrote in Cell Reports that” the increase in interhemispheric alignment of activity by anesthetics appears to reverse the pattern observed in the awake, cognitively engaged brain.”
determined by the degree of separation
The change in phase alignment was largely determined by the fact that distance was a significant factor. Low-frequency waves moved 20 to 30 degrees out of alignment even across a 2.5 millimeter single electrode array.
That would mean a roughly 180-degree shift in phase alignment, which is a complete offset of the waves, across the 20 or so millimeters between arrays in the upper ( dorsolateral ) and lower (ventrolateral ) regions of a hemisphere.
According to Miller, the dependence on location is in line with the notion of waves passing across the cortex. In fact, Miller and Brown’s labs discovered that a powerful low-frequency traveling wave that swept straight across the cortex, overriding higher-frequency straight and rotating waves, in a study conducted in 2022.
The new findings offer a lot of room for future research, Miller said. Does the additional anesthetic propofol also cause this change in phase alignment? What part does the phenomenon of traveling waves play? Could phase alignment explain the difference given that sleep is also characterized by an increase in power in slow wave frequencies but is undoubtedly not the same as anesthesia-induced unconsciousness?
The paper’s other authors are Yumiko Ishizawa, Scott Brincat, Jefferson Roy, Meredith Mahnke, and Bardon, Brown and Miller.
The research was supported by the funding from the United States Department of Energy, National Institutes of Health, Simons Center for the Social Brain, Freedom Together Foundation, and Picower Institute for Learning and Memory.
About this news about research in neuroscience and consciousness
Author: David Orenstein
Source: Picower Institute at MIT
Contact: David Orenstein – Picower Institute at MIT
Image: The image is credited to Neuroscience News
Open access to original research.
Alexandra Bardon and colleagues ‘” Convergent effects of different anesthetics on changes in cortical oscillations ‘ phase alignment.” Cell Reports
Abstract
Convergent effects of various anesthetics on changes in cortical oscillation phase alignment
Despite having a variety of underlying molecular and circuit actions, many anesthetics cause loss of consciousness.
We examine how anesthetic doses of ketamine and dexmedetomidine affect bilateral oscillations in nonhuman primates in order to investigate whether these drugs have convergent effects.
In both hemispheres, phase locking occurs in the ventrolateral and dorsolateral prefrontal cortex, both internally and externally.
However, phase locking has a different nature. With both drugs, nearby prefrontal subregions within a hemisphere show decreased phase alignment.
Local analyses within a region suggest that large moving waves, as well as general cortical distance-based effects, could account for this finding. In contrast, homologous phase alignment across hemispheres increases.
Our findings point to strong cortical phase alignment patterns that are markedly different from those observed when we wake, and that these patterns may be a contributing factor to the loss of responsiveness caused by the use of various anesthetic drugs.
