This is the brain under anesthesia


In earlier studies on brain implants Rodents And EEG readings HumanityBrown said that propofol disrupts communication in the cortex. But in order to further advance scientific development, he and Miller hope to record different areas at the same time as animals slide in and out of consciousness. They hope to use implanted electrodes to listen to the process of individual neurons changing their pitch, in order to understand how and where the complex communication of the brain breaks under anesthesia. For their new research, they implanted 64-channel microelectrodes into four macaques. They are stuck in four parts of the brain: three areas of the cortex and thalamus. The three cortical areas are the frontal lobe, temporal lobe and parietal lobe, which are related to thinking, auditory processing, and sensory information, respectively. The thalamus is approximately the size and shape of a quail egg, located deep in the brain, and transmits information throughout the cortex.

The scientist hit the record on the electrode before flowing into the first batch of propofol, and then watched the monkey slip into a coma. Brown said: “Drugs are everywhere, and they will arrive within a few seconds.” The brain waves crawled slowly. (The neurons in a healthy, awake brain will spike approximately 10 times per second. Under the influence of propofol, the frequency drops to once per second or less.) Brown is not surprised. He has seen these types of slow oscillations in other animals, including humans. But deep electrodes can now answer more precise questions: What is happening between neurons?

Normally, neurons tremble by beating each other. “It’s kind of like an FM radio,” Miller said. “They are on the same channel, and they can talk to each other.” Millions of neurons communicate in this way at many different frequencies. But now, the usual rich frequency becomes a kind of low rhythm—a kind of strange harmony. The higher frequencies disappear, and the neurons stay on the low-frequency channel to communicate. It seemed that the sound in the restaurant was full of children talking loudly, quiet one-on-one, and everything in between, suddenly fell into a buzzing buzz.

Brown believes that the frequency of decreased neural activity during anesthesia is actually more coordinated than any other mental state. Whether you are in a state of alertness, reading, sleeping or meditating, brain waves are chaotic and difficult to interpret. But on the EEG, there is no signal as clear and rhythmic as anesthesia. And, crucially, he believes that it is this unity that undermines consciousness. The endless seemings of the alert brain in the lunch room seem to be noisy chaos, but it is actually a coherent language of memories, feelings, and sensations. The hum of anesthesia is obvious, but this is an information desert.

Miller said: “Propofol appeared like a sledgehammer, but the brain was trapped in this low-frequency mode, and now there is no such possibility.”

Miller and Brown suspected that the thalamus was particularly important for restoring the abundance of sober chaos. An existing theory believes that in order to generate consciousness, this small nodule will synchronize various rhythms in the cortex. Theoretically, if the thalamus stops working, cortical waves cannot keep up with their rhythm to convey cohesive thoughts. “And communication is all In consciousness,” Miller said.

Once they observed that anesthesia flattened communication in the thalamus, the researchers wanted to see if stimulation of the brain area would bring back signs of conscious activity. previous employment Studies have shown that deep brain stimulation can restore partial control of the limbs and the ability to eat in people with traumatic brain injury. However, this idea is new. Miller said: “This is a gamble, it’s a long process.”


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