Hi, my name is Dr. Sanjay Singh. I am the director of the CHI Health Neurological Institute. I'm also the professor and chair of Neurology at Creighton University School of Medicine.
What is Consciousness?
What is consciousness? That has been a question that has vexed philosophers and scientists for millennia. But now it has found its rightful place in neuroscience, because that is where we can answer this question. Consciousness is an essential attribute of the human brain. This is a model of the brain. As you can see up top is your cortex of the brain, which is what makes us uniquely human. But if you look at the undersurface, there is a depth of the brain and there's a structure called the thalamus. That structure has neuronal circuits, which are literally wiring of brain cells that goes from the depths the thalamus to the cortex.
How Does the Brain Regulate Consciousness?
It is the oscillation in this fundamental circuit that determines your state of consciousness. If that oscillation is at 3 hertz, that mean three cycles per second, you are unconscious, sleeping, or comatose. If that oscillation is at 8 or 9 hertz, then you are conscious and awake. This was actually discovered in animal models. When they discovered it, they could actually switch the frequency from 3 hertz when the animal fell unconscious, to 8 hertz when the animal woke up.
What are the Different States of Consciousness?
So right now we have three states of human consciousness that we are aware of. One is awake, sleep, and dreams. So in Neuroscience those are the three states of human consciousness that we talk about. So what is sleep? Sleep is when this fundamental circuit oscillates at a frequency that is lower. At 3 hertz you are in deep sleep. We have discovered the fundamental circuit of human consciousness, and at least in animals we can switch an animal from awake to sleeping just by flipping a switch with changes the oscillating frequencies.
What Does this Mean for Those in a Coma?
This study of consciousness has led us to try and modulate human consciousness in comatose individuals. Now, there are different types of coma, but what we do is we can put electrodes from the top into the thalamus, and by those electrodes we can change the oscillating frequency off the circuit. In a few cases, what they have been able to do, again this is very recent science, they've been able to wake people up from comas. This has profound implications, because imagine all the patients in a coma in the ICUs, if there was a possibility to wake them up for a little bit, for a few hours, for a few days, few weeks, or even a few years, that would change the way we practice medicine today. So it is an ability that is unique about which we know so much about today where we can change human consciousness by inserting electrodes into the brain.
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