The PET brain-scan breakthrough

25:53what. Okay. The receiving end of the chemical signal to turn on. Yes. It's It's receiving the glutamate and somehow that receiver has something to do with ketamine. Okay? So what these guys did was they used positron emission tomography. This is an imaging method where you basically like you have the patient inject some radioactive chemical. It's not that harmful, but it's what it does is that chemical becomes a tracer. It releases positrons as it makes its way through. Positrons are the antimatter version of the electron. And if you have a positron detector, then you can detect these positrons and you can see where the chemical is going. So it's it's a way

26:34it's a way to basically look at what's happening inside the body or track what's happening inside the body from outside the body. Yes, exactly. And so what what these guys at the City University of Yokohama they developed a PET tracer, a positive a positron tracer that had been developed earlier. This tracer allows them to visualize that AMPA R directly because it somehow either connects to the AMPA R or like interacts with it in some way. So, we can actually map where the AMPA R receptors are in the brain. Got it. Okay? That's step one. We figured out a way to trace and map out where the AMPA R receptors are.

27:14Now, you give your patients ketamine. Cuz we first identifying the location >> Yes. That's what we want to do. >> the thing we care about is happening. But, we didn't actually know where the like we needed to know where the locations were first. >> Yeah, we knew that it was this thing, yes. But, we don't know we have no way of figuring out where it is. And like what are the dynamics when somebody gets ketamine? How does that change? Now, we do. Now, we've got this tracer that goes in, it's going to shoot out positrons, and we've got a big positron detector. So, wherever the positrons are coming from, we know that's where the AMPA R receptors are. Mhm. Okay? Then, we give them ketamine. Yes. And we look at how these antidepressant effects evolve that AMPA R activity, that receptor activity. And that's what they've done, okay? >> They they used 34 patients that were

27:55diagnosed with this um treatment-resistant depression and 49 healthy patients that were in control. They gave half ketamine, half like just, you know, placebo cuz you got to have the that control. >> Mhm. And then what it shows is the the people who have this treatment-resistant depression, first of all, they had widespread abnormalities in their AMPA R density just without even the treatment and everything. Those who have depression have a very different AMPA R density in their brain compared to healthy patients. Can I do a quick pause here on that point because well, just to double click on it, there is a structural a physical structural difference

28:36>> Mhm. uh at the neuron level >> Yeah. for people who have this treatment-resistant depression than the control than than others. Yeah. So, for