Last month, researchers in Germany and Canada did something I would never volunteer to do. They created the first ever digital 3D map of the human brain. They called it BigBrain, but if I had worked on the project, I would have called it something a little less friendly, probably something like BigPain, but with more profanity. BigBrain was not just an amazing study in anatomy, it was a challenge to patience and a testament to persistence.
So how did they do it? It’s known as histology, and as a behavioral neuroscientist, it’s the bane of my existence. Histology involves a series of tedious steps that allow us to visualize structural elements of animal tissue in relation to their function. In short, it lets us turn tissue into a pretty picture.
People say a picture is worth a thousand words, but in this case, it was worth a thousand hours. Yep, it took about 1,000 uninterrupted hours for scientists to make BigBrain. That’s 125 eight-hour work days in a row. Now imagine that with no lunch breaks or weekends. Of course they must have taken breaks, but you get the idea.
So what did a day in the life of these scientists involve? If I could guess based on experience, there was probably a lot of hunching over, excessive squinting, endless repetition, copious amounts of coffee, alternating periods of complete silence, blasting music, mindless banter, intelligent conversation and talk radio until it hurt.
But here’s what they really did.
First, they procured the tissue, the brain of a 65-year-old woman, deceased, of course. Then they used a giant microtome to cut the brain, embedded in wax, into 7,400 slices. A microtome is like a meat slicer, but instead of olive loaf or provolone, it’s a brain. Each slice was 20 µm thick. To put this into perspective, the thickness of a sheet of paper is about 97 microns. They then mounted the slides onto a grid, stained them for cell bodies and took pictures of them. They touched up the tissue, both manually and digitally. Finally, using the images and magnetic resonance imaging (MRI), they reconstructed the brain– in 3D, cafefully matching structures and folds along the way.
But no brain is the same. Development, not just geometry, helps determine cortical borders. Work is currently underway to address this concern. But for now, BigBrain is available to the public in hopes that maybe they can help.What makes this strictly anatomical map so special? The resolution! Neuroscientists have a frame of reference, that before now, no other map of the human brain has been able to provide. We can see the structures in a lot more detail.
The creators of BigBrain plan to use this high resolution to their advantage and combine their anatomical map of cells and regions of the brain to other maps that show gene-expression, neural projections and brain activity. This combo would include chartering the distributions of certain receptors for neurotransmitters, fiber bundles and genetic information.
Every neuroscientist should send a thank you note to the maker’s of BigBrain. Their dedicated labor has made our work a heck of alot easier. – by: JoAnna Klein
