Charan Ranganath

You see these very slow waves where it's like very excitable and then very unexcitable. It goes up and down. And on top of them, you'll see these little sharp wave ripples. And when there's a ripple in the hippocampus, you tend to see a sequence of cells that resemble a sequence of cells that fire when an animal is actually doing something. So it almost is like a little, people call it replay.

I think it's a little bit, I don't like that term, but it's basically a little bit of a compressed play of the sequence of activity in the brain that was taking place earlier. And during those moments, there's a little window of communication between the hippocampus and these areas in the neocortex.

I think it's a little bit, I don't like that term, but it's basically a little bit of a compressed play of the sequence of activity in the brain that was taking place earlier. And during those moments, there's a little window of communication between the hippocampus and these areas in the neocortex.

I think it's a little bit, I don't like that term, but it's basically a little bit of a compressed play of the sequence of activity in the brain that was taking place earlier. And during those moments, there's a little window of communication between the hippocampus and these areas in the neocortex.

And so that, I think, helps you form new memories, but it also helps you, I think, stabilize them, but also really connect different things together in memory and allows you to build bridges between different events that you've had. And so this is one of, at least, our theories of memory. sleep and its real role in helping you see the connections between different events that you've experienced.

And so that, I think, helps you form new memories, but it also helps you, I think, stabilize them, but also really connect different things together in memory and allows you to build bridges between different events that you've had. And so this is one of, at least, our theories of memory. sleep and its real role in helping you see the connections between different events that you've experienced.

And so that, I think, helps you form new memories, but it also helps you, I think, stabilize them, but also really connect different things together in memory and allows you to build bridges between different events that you've had. And so this is one of, at least, our theories of memory. sleep and its real role in helping you see the connections between different events that you've experienced.

The connections between different events, right? So it's like you see me now, you see me next week, you see me a month later. You start to build a little internal model of how I behave and what to expect of me. And we think sleep, one of the things that allows you to do is figure out those connections and connect the dots and find the signal and the noise.

The connections between different events, right? So it's like you see me now, you see me next week, you see me a month later. You start to build a little internal model of how I behave and what to expect of me. And we think sleep, one of the things that allows you to do is figure out those connections and connect the dots and find the signal and the noise.

The connections between different events, right? So it's like you see me now, you see me next week, you see me a month later. You start to build a little internal model of how I behave and what to expect of me. And we think sleep, one of the things that allows you to do is figure out those connections and connect the dots and find the signal and the noise.

And this is actually the reason why I got into this whole field of science. When I was in grad school, fMRI was just really taking off as a technique for studying brain activity. And what's beautiful about it is you can study the whole human brain, and there's lots of limits to it, but you can basically do it in person without sticking anything into their brains. And very non-invasive.

And this is actually the reason why I got into this whole field of science. When I was in grad school, fMRI was just really taking off as a technique for studying brain activity. And what's beautiful about it is you can study the whole human brain, and there's lots of limits to it, but you can basically do it in person without sticking anything into their brains. And very non-invasive.

And this is actually the reason why I got into this whole field of science. When I was in grad school, fMRI was just really taking off as a technique for studying brain activity. And what's beautiful about it is you can study the whole human brain, and there's lots of limits to it, but you can basically do it in person without sticking anything into their brains. And very non-invasive.

I mean, for me, being an MRI scanner is like being in the womb. I just fall asleep. Yeah. If I'm not being asked to do anything, I get very sleepy, you know. But you can have people watch movies while they're being scanned, or you can have them do tests of memory, like giving them words and so forth to memorize.

I mean, for me, being an MRI scanner is like being in the womb. I just fall asleep. Yeah. If I'm not being asked to do anything, I get very sleepy, you know. But you can have people watch movies while they're being scanned, or you can have them do tests of memory, like giving them words and so forth to memorize.

I mean, for me, being an MRI scanner is like being in the womb. I just fall asleep. Yeah. If I'm not being asked to do anything, I get very sleepy, you know. But you can have people watch movies while they're being scanned, or you can have them do tests of memory, like giving them words and so forth to memorize.

But what MRI is itself is just this technique where you put people in a very high magnetic field. Typical ones we would use would be 3 Tesla, to give you an idea. Yeah. So a 3-tesla magnet, you put somebody in, and what happens is you get this very weak but measurable magnetization in the brain. And then you apply a radiofrequency pulse, which is basically a different electromagnetic field.

But what MRI is itself is just this technique where you put people in a very high magnetic field. Typical ones we would use would be 3 Tesla, to give you an idea. Yeah. So a 3-tesla magnet, you put somebody in, and what happens is you get this very weak but measurable magnetization in the brain. And then you apply a radiofrequency pulse, which is basically a different electromagnetic field.

But what MRI is itself is just this technique where you put people in a very high magnetic field. Typical ones we would use would be 3 Tesla, to give you an idea. Yeah. So a 3-tesla magnet, you put somebody in, and what happens is you get this very weak but measurable magnetization in the brain. And then you apply a radiofrequency pulse, which is basically a different electromagnetic field.

And so you're basically using water, the water molecules in the brain as a tracer, so to speak. And part of it in fMRI is the fact that these magnetic fields that you mess with by manipulating these radio frequency pulses and the static field, and you have things called gradients which change the strength of the magnetic field in different parts of the head.