Bliss Chapman

And what we're trying to do when we place an electrode or parking it next to a neuron is that you're trying to measure these local changes in the potential, again, mediated by the movements of the ions. And what's interesting, as I mentioned earlier, there's a lot of physics involved. And the two dominant physics for this electrical recording domain is diffusion physics and electromagnetism.

Where one dominates, where Maxwell's equation dominates versus Fick's law dominates, depends on where your electrode is. If it's close to the source, mostly electromagnetic based, when you're farther away from it, it's more diffusion based. Essentially, when you're able to park it next to it, you can listen in on those individual chatter and those local changes in the potential.

Where one dominates, where Maxwell's equation dominates versus Fick's law dominates, depends on where your electrode is. If it's close to the source, mostly electromagnetic based, when you're farther away from it, it's more diffusion based. Essentially, when you're able to park it next to it, you can listen in on those individual chatter and those local changes in the potential.

Where one dominates, where Maxwell's equation dominates versus Fick's law dominates, depends on where your electrode is. If it's close to the source, mostly electromagnetic based, when you're farther away from it, it's more diffusion based. Essentially, when you're able to park it next to it, you can listen in on those individual chatter and those local changes in the potential.

And the type of signal that you get are these canonical textbook neural spiking waveform. The moment you're further away, and based on some of the studies that people have done, Christoph Koch's lab and others, once you're away from that source by roughly around 100 micron, which is about the width of a human hair, you no longer hear from that neuron.

And the type of signal that you get are these canonical textbook neural spiking waveform. The moment you're further away, and based on some of the studies that people have done, Christoph Koch's lab and others, once you're away from that source by roughly around 100 micron, which is about the width of a human hair, you no longer hear from that neuron.

And the type of signal that you get are these canonical textbook neural spiking waveform. The moment you're further away, and based on some of the studies that people have done, Christoph Koch's lab and others, once you're away from that source by roughly around 100 micron, which is about the width of a human hair, you no longer hear from that neuron.

You're no longer able to have the system sensitive enough to be able to record that particular local membrane potential change in that neuron. Just to kind of give you a sense of scale also, when you look at 100 micron voxel, so 100 micron by 100 micron by 100 micron box in a brain tissue, there's roughly around 40 neurons and whatever number of connections that they have.

You're no longer able to have the system sensitive enough to be able to record that particular local membrane potential change in that neuron. Just to kind of give you a sense of scale also, when you look at 100 micron voxel, so 100 micron by 100 micron by 100 micron box in a brain tissue, there's roughly around 40 neurons and whatever number of connections that they have.

You're no longer able to have the system sensitive enough to be able to record that particular local membrane potential change in that neuron. Just to kind of give you a sense of scale also, when you look at 100 micron voxel, so 100 micron by 100 micron by 100 micron box in a brain tissue, there's roughly around 40 neurons and whatever number of connections that they have.

So there's a lot in that volume of tissue. So the moment you're outside of that, there's just no hope that you'll be able to detect that change from that one specific neuron that you may care about. Yeah, but as you're moving about the space-

So there's a lot in that volume of tissue. So the moment you're outside of that, there's just no hope that you'll be able to detect that change from that one specific neuron that you may care about. Yeah, but as you're moving about the space-

So there's a lot in that volume of tissue. So the moment you're outside of that, there's just no hope that you'll be able to detect that change from that one specific neuron that you may care about. Yeah, but as you're moving about the space-

Yeah, you want to listen to the chatter. And at the end of the day, you also want to basically let the software do the job of decoding. And just to kind of go to why ECOG and EEG work at all, right? When you have these local changes, you know, obviously it's not just this one neuron that's activating. There's many, many other networks that are activating all the time.

Yeah, you want to listen to the chatter. And at the end of the day, you also want to basically let the software do the job of decoding. And just to kind of go to why ECOG and EEG work at all, right? When you have these local changes, you know, obviously it's not just this one neuron that's activating. There's many, many other networks that are activating all the time.

Yeah, you want to listen to the chatter. And at the end of the day, you also want to basically let the software do the job of decoding. And just to kind of go to why ECOG and EEG work at all, right? When you have these local changes, you know, obviously it's not just this one neuron that's activating. There's many, many other networks that are activating all the time.

And you do see sort of a general change in the potential of this electrode, like this charged medium, right? And that's what you're recording when you're farther away. I mean, you still have some reference electrode that's stable in the brain that's just electroactive organ. And you're seeing some combination aggregate action potential changes. And then you can pick it up, right?

And you do see sort of a general change in the potential of this electrode, like this charged medium, right? And that's what you're recording when you're farther away. I mean, you still have some reference electrode that's stable in the brain that's just electroactive organ. And you're seeing some combination aggregate action potential changes. And then you can pick it up, right?

And you do see sort of a general change in the potential of this electrode, like this charged medium, right? And that's what you're recording when you're farther away. I mean, you still have some reference electrode that's stable in the brain that's just electroactive organ. And you're seeing some combination aggregate action potential changes. And then you can pick it up, right?

It's a much slower changing process. but there are these like canonical kind of oscillations and waves, like gamma waves, beta waves, like when you sleep, that can be detected, because there's sort of a synchronized kind of global effect of the brain that you can detect.