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It’s been well over a century since neuron discovery was at the forefront of science. It was a Spanish neuroanatomist by the name of Santiago Ramón y Cajal who showed how neurons allow us to walk, talk, think and generally exist–which awarded him a Nobel Prize. But since then, progress in distinguishing between neurons has been slow. Even as microscopes have improved, neuroscientists have only been able to define our brain cells by two labor-intensive characteristics: their looks, and how they fire.
Because of this, neuroscientists around the world have been rushing to find and adopt some new and more nuanced ways to characterize neurons. Some of these methods are things like sequencing technologies which can reveal how cells in the exact same DNA turn genes on and off in unique ways. The thing is those unique methods are starting to reveal that the brain is more like a diverse forest with branching energies and various nodes.
Because of this, neurologists have discovered a new neuron that by this point is believed to be only in the human brain! They’re calling it the “rose hip” neuron, because of the long nerve fibers that are so densely bundled up. The structure reminds you of a rose without petals.
So what do these rose hip cells do? Well according to Ed Lein, an Allen Institute for Brain Science investigator, said, they act as a brake system of sorts. In short, there are two types of neurons: there are the cells that send information called the excitatory cells, and the inhibitory cells which slow down or stop excitatory cells from firing. The rose hip cells belong in the inhibitory camp and according to their physiology, they seem like a potent current-curber.
The discovery of the rose hip cell was actually discovered by two different teams in tandem. Lein’s group harvested frozen tissue from two human brains that were donated to Allen Institute. They were isolated in a well to be analyzed as well. While they used techniques to analyze them, they were able to find 16 different cell types: 11 inhibitory neurons, one excitatory neuron, as well as for non-neural cells.
While that was happening, a team in Hungary was analyzing live brain tissue samples from people who undergone brain surgery. By using traditional techniques the team was able to identify a group of well-connected neurons which miraculously matched with one of Lein’s group cell types. But when they went to check the cells in a mouse brain, they couldn’t find anything similar.
All in all the discovery is a miracle mainly due to the fact it is so difficult to get live human brain tissue. For this reason, a lot of the characterizing work with human neurons is done on test mice. It’s why neuroscientists aren’t entirely certain if the rose hip cell is found only in humans. That being said, there is hope as neuroscientists have been taking an approach by using frozen tissue, of which there is plenty of sitting in biobanks all across the globe.