Charan Ranganath

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.

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.

So we tweak them in different ways, but the basic idea that we use in fMRI is that blood is flowing to the brain. And when you have blood that doesn't have oxygen on it, it's a little bit more magnetizable than blood that does, because you have hemoglobin that carries the oxygen, the iron, basically, in the blood that makes it red.

So we tweak them in different ways, but the basic idea that we use in fMRI is that blood is flowing to the brain. And when you have blood that doesn't have oxygen on it, it's a little bit more magnetizable than blood that does, because you have hemoglobin that carries the oxygen, the iron, basically, in the blood that makes it red.

So we tweak them in different ways, but the basic idea that we use in fMRI is that blood is flowing to the brain. And when you have blood that doesn't have oxygen on it, it's a little bit more magnetizable than blood that does, because you have hemoglobin that carries the oxygen, the iron, basically, in the blood that makes it red.

And so that hemoglobin, when it's deoxygenated, actually has different magnetic field properties than when it has oxygen. And it turns out when you have an increase in local activity in some part of the brain, the blood flows there. And as a result, you get a lower concentration of hemoglobin that is not oxygenated. And then that gives you more signal.

And so that hemoglobin, when it's deoxygenated, actually has different magnetic field properties than when it has oxygen. And it turns out when you have an increase in local activity in some part of the brain, the blood flows there. And as a result, you get a lower concentration of hemoglobin that is not oxygenated. And then that gives you more signal.

And so that hemoglobin, when it's deoxygenated, actually has different magnetic field properties than when it has oxygen. And it turns out when you have an increase in local activity in some part of the brain, the blood flows there. And as a result, you get a lower concentration of hemoglobin that is not oxygenated. And then that gives you more signal.

So I gave you, I think I sent you a gif, as you like to say.

So I gave you, I think I sent you a gif, as you like to say.

So I gave you, I think I sent you a gif, as you like to say.

We could have called it a stern rebuke, perhaps.

We could have called it a stern rebuke, perhaps.

We could have called it a stern rebuke, perhaps.

This would be basically a whole movie of fMRI data. And so when you look at it, it's not very impressive. It looks like these very pixelated maps of the brain, but it's mostly kind of like white. But these tiny changes in the intensity of those signals that you probably wouldn't be able to visually perceive, like about 1%, can be statistically very, very large effects for us.

This would be basically a whole movie of fMRI data. And so when you look at it, it's not very impressive. It looks like these very pixelated maps of the brain, but it's mostly kind of like white. But these tiny changes in the intensity of those signals that you probably wouldn't be able to visually perceive, like about 1%, can be statistically very, very large effects for us.

This would be basically a whole movie of fMRI data. And so when you look at it, it's not very impressive. It looks like these very pixelated maps of the brain, but it's mostly kind of like white. But these tiny changes in the intensity of those signals that you probably wouldn't be able to visually perceive, like about 1%, can be statistically very, very large effects for us.

And that allows us to see, hey, there's an increase in activity in some part of the brain when I'm doing some tasks like trying to remember something. And I can use those changes to even predict, is a person going to remember this later or not? And the coolest thing that people have done is to decode what people are remembering from the patterns of activity.

And that allows us to see, hey, there's an increase in activity in some part of the brain when I'm doing some tasks like trying to remember something. And I can use those changes to even predict, is a person going to remember this later or not? And the coolest thing that people have done is to decode what people are remembering from the patterns of activity.

And that allows us to see, hey, there's an increase in activity in some part of the brain when I'm doing some tasks like trying to remember something. And I can use those changes to even predict, is a person going to remember this later or not? And the coolest thing that people have done is to decode what people are remembering from the patterns of activity.