They just used the MRI to map a high-resolution image obtained via light sheet microscopy. I doubt you can do that with living animals. Without slicing the brain that is.
The number in the title is misleading but what you write here is also misleading.
> The diffusion tensor images (DTI) @ 15 μm spatial resolution are 1,000 times the resolution of most preclinical rodent DTI/MRI. Superresolution track density images are 27,000 times that of typical preclinical DTI/MRI.
The resolution of the raw MRI images is significantly higher, without that increased resolution it would be impossible to align the light sheet images. The light sheet images are not use to "improve" MRI resolution.
Yeah, they kind of blow past light sheet microscopy, but I'm optimistic that this can still be quite useful. There are brain banks with already donated brains that we could use to learn about diseases, and I imagine many organ donors would be happy to have their brains sliced up for science.
Light sheet microscopy is actually pretty neat. You can use it on a whole brain without slicing it but not on a living animal. The tissue needs to go through a special fixing procedure first
A key problem with high-res MRI in a living organism is the scan time. Even fast acquisition techniques like EPI require around 50 milliseconds per slice. But if you want good resolution and contrast you're doing a spin echo which takes quite a bit longer. At some point you run into motion blur caused by the mere involuntary contraction of blood vessels, and that's before you consider the difficulty with patient compliance to the directive: "hold still".
Indeed. To say nothing of gating acquisitions to breathing, head motion, eye cicadas, glymphatic flow, etc.
The highest resolution MR images I have (yet) obtained were ~20 µm^3 voxels on ex vivo (human) tissue samples fixed in agar with Gd3+ as a dopant, scanned at 12 T on a preclinical scanner. The coupled vibration of the gradient set causing blurring in the image domain at the extremities of the FOV was the limiting factor. I recall I did a partial Fourier acquisition – as ultimately we were limited by both T2* and vibration – and ended up trying to do POCS on a 4096^3 dataset and just needing tons and tons of ram to do it over something useful, like a weekend. Happy memories.
If you want to scan the entire organism, sure. But higher resolution MRI can also mean "scan a smaller part, with good detail, in the same amount of time". I could imagine this being useful for e.g. getting a high resolution image of a tumour after conventional imaging was used to locate it.
One more leap like this and we'll be able to resolve individual dendrites and obtain a complete connectome. Combined with microscopic slices (with suitable immunohistological staining), we'd be getting close to obtaining the data necessary for brain uploading - at least in mice.
Yes, I'm aware of what the connectome is. Someone in my lab is working on a piece of it. My question was regarding the term upload, most people don't mean a replica when they use that term
One thing that the MRI studies don't address are the types of synaptic connections. Neurons aren't all just excitatory of inhibitory. There's a massive amount of modulation happen with numerous types of neurotransmitters and other signaling molecules.
There is also a significant amount of non-synaptic interaction through neuropeptides, extracellular vesicles, diffusible molecules and active pumping of the CFS, glial networks, electric field effects, plus all of the unknowns.
We've had the complete C. elegans connectome for 30+ years, and know very little about how it actually generates behaviour... because synapses are only a small part of the picture.
I'm not sure why you got downvoted, you're absolutely correct. There are so many pieces to how biological neurons work, we barely understand it. Even electrophysiological studies are missing out on a ton of info
