If you've ever been fascinated by your own brain, you're not alone. Neuroscience, the study of the brain, dates all the way back to 1,700 B.C. in ancient Egypt – though the ancient Egyptians believed the brain was just stuffing to keep your skull from caving in (yes, really!).
Not surprisingly, scientists have come a long way from the "head stuffing" days, and left other out-there beliefs – like that your head shape determines your intelligence – behind.
We now know that different regions of the brain are responsible for different tasks, and that brain cells fall into two major categories. Neurons, which are the the "thinking" cells, and glia, which are the supporting cells that help the neurons do their job. Scientists have identified lots of subtypes of neurons and glia, including as many as 10,000 different types of neurons.
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And they've just found one more.
Introducing the rosehip neuron, a new and complex type of neuron whose discovery was published this week. Not only is the rosehip neuron new and rare, but it might be involved in some of our most complex brain processes.
So, What's a Rosehip Neuron?
Researchers first discovered the rosehip neuron looking under a microscope at slices of human brain tissue. They saw small, bushy-looking cells with plenty of "branches" – called dendrites – that could connect to several other nerve cells.
While the cells looked unique, they weren't sure they were a new type of cell until they did genetic analysis. By looking at which genes were active or inactive within the cell – kind of like a genetic "fingerprint" – they determined it was different than any of the similar-looking neurons discovered in mice.
They dubbed it a rosebud neuron because the small bulges on its dendrites, where it connects to other nerves, look like rosebuds on a branch.
How Does the Rosehip Neuron Work?
The new neuron belongs to a class of nerves called inhibitory neurons. This class of neurons works by turning other nerves off, slowing down or halting communication.
Think of inhibitory neurons as the traffic cops of the brain. If there's no traffic cop around, the traffic will run freely, like normal. Once the traffic cop steps into traffic, though, the cars stop – and won't start again until he lets them.
That's how inhibitory neurons affect their neighboring cells. The neighboring cells won't fire until the inhibitory neuron turns off. If the inhibitory neuron is active – and the traffic copy is "on duty" – the neighboring nerves turn off. By "directing traffic" in your brain, inhibitory nerves help manage how you experience pain, control the way your muscles move, and more.
Why Is This Discovery Important?
One reason rosehip nerves matter is their complexity. So far, scientists have only discovered them in human brains – and they aren't present in mice or rats. That might mean that rosebud neurons are one of the cells that makes our brain more evolved than the brains of some other mammals.
Rosebud neurons are also rare. They're mostly found in a region of your brain called the cortex, which is packed with inhibitory neurons. And their position in the cortex means they might have a powerful influence on which neurons in your brain are active and which ones aren't – it means they could have a "master switch" to control your brain function.
While it will take years (or decades!) to fully uncover how the rosebud neuron works, who knows – it just might help explain how humans evolved and why our brains work the way they do.