Going under anesthesia? Scientists reveal what happens inside your unconscious brain

How is your brain like a crowd at a soccer match? Substitute basketball for soccer, if you prefer. Keep reading. 

The cerebral cortex has been thought of as the part of the human brain in which conscious thought is processed. It would be expected that the cortex would be less active when a patient is under general anesthesia. A new study reports, however, that under general anesthesia, just some of the cortical cells record less activity. Other cells increase activity and synchronize.

These findings may lead to improvements in anesthetic drugs and better surgical outcomes.

The work of Professor Botond Roska and his group of researchers at the University of Basel, Switzerland, reveals how different cell types in the cerebral cortex change in activity during general anesthesia. This new information increases understanding about induction of unconsciousness via anesthetic drugs.

It has been known for the last 100 years that some cells in the cortex are active, alternating between periods of high and low activity, during general anesthesia. Attaching EEG electrodes to the scalp has been one of the few means available to detect cortical activity, but it doesn’t allow identification of the cells which are active.

The cortex is composed of different cell types; each type serves different functions. Different general anesthetics act on different receptors, located on different types of neurons throughout the brain. All general anesthetics, however, ultimately have the same effect – loss of consciousness.

“We were interested in finding if there is a common neuronal mechanism across different anesthetics,” says Dr. Martin Munz, co-leader of the study, in a statement.

To address the question, researchers used genetic tools, and mice with variable characteristics bred just for the study, to label individual cortical cell types. They found that in contrast to what had previously been suspected, only one specific cell type within the cortex, labeled “layer 5 cortical pyramidal neurons,” showed an increase in activity when the animals were exposed to different anesthetics.

“Each anesthetic induces a rhythm of activity in layer 5 cortical pyramidal neurons. Interestingly, these rhythms differed between anesthetics. Some were slower, and some were faster,” explains Dr. Arjun Bharioke, another co-leader of the study. “However, what was common across all anesthetics was that they all induced an alignment of activity. When they were active, all layer 5 cortical pyramidal neurons were active at the same time. We called this ‘neuronal synchrony.’

“It seems that instead of each neuron sending different pieces of information during anesthesia, all layer 5 cortical pyramidal neurons send the same information,” he continues. “One could think of this as when people in a crowd transition from talking to each other, for example, before a soccer or basketball game, to when they are cheering for their team, during the game. Before the game starts, there are many independent conversations. In contrast, during the game, all the spectators are cheering on their team. Thus, there is only one piece of information being transmitted across the crowd.”

Adds Dr. Alexandra Brignall, third co-leader of the study and a veterinarian: “Anesthetics are very powerful, as anyone who has been in a surgery can attest to. But they are also not always easy to use. During a surgery, one has to continuously monitor the depth of the anesthetic to ensure that the patient is not too deep or too shallow. The more we know how anesthetics work and what they do in the brain, the better. Maybe this will help researchers develop new drugs to specifically target the cells in the brain associated with unconsciousness.” 

Findings are published in the open access journal Neuron.

The contents of this website do not constitute advice and are provided for informational purposes only. See our full disclaimer

About the Author

Dr. Faith Coleman

Faith A. Coleman MD
Dr. Coleman is a graduate of the University of New Mexico School of Medicine and holds a BA in journalism from UNM. She completed her family practice residency at Wm. Beaumont Hospital, Troy and Royal Oak, MI, consistently ranked among the United States Top 100 Hospitals by US News and World Report. Dr. Coleman writes on health, medicine, family, and parenting for online information services and educational materials for health care providers.

Comments

  1. The doctor he put me to sleep,
    But tried not to sleep me too deep,
    The drug that he used,
    It made me to snooze,
    And caused me to keep a deep sleep.

    When after the sleep I awoke,
    The voice that I heard spoke a joke,
    Not funny by half,
    ‘Twas more of a gaffe,
    A signal to stoke the woke folk.

    The room that my gurney was in,
    Had TVs tuned to CNN,
    The voice that of Joe,
    It whispered so low,
    “What women? They’re not feminine.”

    1. Ah, one of those people who feel the need to make politically motivated comments of any story with a comment section. It is kind of funny that you spend as much time as you do, in that activity, and it’s having absolutely no impact on anything. Also, it shows that you’re not all that different from those with opposite political beliefs, who do the same thing. Your ideology might be different but when it comes to personality and behavior, you’re no different from those you rant against.

      1. Was that a reference to alt-leftists and the fact that they deny there is such a thing as a woman or a man?

        I caught that during the latest SCOTUS confirmation hearings. The most recently confirmed Supreme Court justice doesn’t know what a woman is or even how to define the word.

  2. What about sleep? It’s different than anesthesia, but it is also a loss of consciousness.

  3. it is funny how in some places Faith’s BA is in Journalism and in others it is in Arts. Combine that with the lack of any info in the article. Kind of draws the whole actually being a Dr into question.

  4. Electrical magnetic signals control your mind which is just light trapped in a electrical magnetic field also known as a halo it’s why everything in your body works at light speed because your idea just sunlight silly right your literally the bolts of lightning that Zeus the sun is tossing from the sky a bolt of lightning is how a electrical magnetic signals looks like trapped in a field duh.

  5. Electrical magnetic signals control your mind which is just light trapped in a electrical magnetic field also known as a halo it’s why everything in your body works at light speed because your indeed just sunlight silly right your literally the bolts of lightning that Zeus the sun is tossing from the sky a bolt of lightning is how a electrical magnetic signal looks like trapped in a field duh anyone got a light bulb because your that light projected out from it now that’s a idea

  6. Electrical magnetic signals control your mind which is just light trapped in a electrical magnetic field also known as a halo it’s why everything in your body works at light speed because your indeed just sunlight silly right your literally the bolts of lightning that Zeus the sun is tossing from the sky a bolt of lightning is how a electrical magnetic signal looks like trapped in a field duh anyone got a light bulb because your that light projected out from it now that’s a idea there called atoms you know Einstein all matter is frozen light also called image the none existence of matter is light on the move it cant existence to you traveling at light speed only in its frozen state can it a condensation of light slower then light speed your image

  7. I don’t think there is any meaning to the fact that layer 5 pyramidal neurons are firing at the same time. It is only because all inhibitory neurons to the pyramidal neurons have been silenced by the anesthesia.

Leave a Reply

Your email address will not be published.