Brain Mapping Tech Blows Brains Up 20x Like a Balloon
First came light-activated neurons. Then came transparent brains and creepy mini-brain blobs. Now scientist have found a way to literally blow brain tissue up like a balloon up to 20 times their normal size, allowing us to peek into mouse brains in unprecedented detail.
The method, iterative expansion microscopy (iExM), comes from neuroscientist wizard Dr. Ed Boyden's lab at MIT. For those not in the know, Boyden had previously helped develop optogenetics--using light to activate neurons--that's led to some fascinating studies such as memory inception in mice. (I shamelessly admit that I'm a total fangirl!)
I explain in a lot more detail how iExM works here, but in a nutshell, scientists use a machine somewhat similar to a deli meat slicer to very thinly section brains into skinny pieces. They then embedded the sections in a super absorbant gel-like substance normally found in baby diapers, and "tagged" the proteins they want to image with a custom molecule "flair".
After tagging, the brain-gel hybrid is treated with a meat tenderizer chemical that destroys the connective tissue holding the piece together. The scientists then add water, and watched the brain-gel expand about 4.5 times and the molecular flairs drift apart. This whole process is then repeated (hence the "iterative" part) to blow the brain up roughly 20 times.
Under the microscope, scientists could see teeny-tiny structures much more clearly than before. This includes actually seeing some of the proteins that form our synapses, the connection between neurons where learning, thought and memory happens. The long-term goal is to use the technique to map big portions of the brain in exquisite detail, with the hope that we will eventually understand how the brain works and maybe even emulate it.
For now, however, treat your eyes to some seriously cool-looking footage of what blown-up brain tissue looks like under the microscope after reconstruction.
In the above video, each blobby-looking branch is skinny dendrite--the input cable from which neuron cell bodies receive information. The blobs are dendritic spines, mushroom-shaped protrusions where synapses sit on.