It's one of the oldest questions on the planet: what sets us apart from the rest of the animal kingdom? It's true that as we're dragged, kicking and screaming into the future, some of those perceived differences are shrinking. We now know that dolphins have language, elephants have ritual and mourn their dead, and some other primate species have entered the stone age. Still, there's a difference. No other animal on the planet can open up a magic box and write about its own consciousness, for better or worse, and that's probably not just due to how awesome our thumbs are. The nuts-and-bolts science of figuring out what makes our brains tick is also one of the scientific disciplines where there's still a lot to learn, not least because of the difficulty in finding human brains to poke around in. Neurologists most often use mice as surrogates, because the structure of mammalian brains are generally the same. Generally the same doesn't mean they're exactly the same, however.
According to a new paper published in the journal Nature Neuroscience, an international team of neurologists have discovered a new and mysterious brain cell present in the human brain and not present in the brains of mice. The team of scientists are calling it the "rosehip" neuron as the structure of the cell resembles the coastal rosehip bush. According to the paper, the rosehip neuron represents about ten percent of the human neocortex. Because of how difficult it is to actually study human brains, the researchers say there could be a higher density throughout the rest of the brain as well.
So what do these rosehip neurons do, and what makes them special? At this point scientists only have their best guesses, but they found that rosehip neurons act as inhibitory factors in the brain, and are connected to a type of neuron called "pyramidal neurons" that are excitory cells. That is, rosehip neurons shut signals down and restrain activity rather than boost signals or send information of their own. According to Trygve Bakken, a lead author of the paper:
"They have the potential to sort of put the brakes on the excitability [of pyramidal neurons]."
Well that's not that exciting, you're probably thinking. Understandable, but stay with me. While the researchers don't know yet how that effects cognition, we can do some wild speculation.
Humans are like other animals in regards to our base instincts. We all know the fight-or-flight response. We all get cranky when we're hungry, and we'll go to extreme lengths when we're desperate. At the far end end of instinctual responses, we're just like other animals. However, at the not-so-extreme end we differ quite a bit. What other animal can say "I'm hungry, but I really need to finish this so I'll just deal with it and eat in an hour"? We can even override the fight-or-flight reaction to a certain degree. Could it be that these rosehip neurons are the mechanism by which we can sometimes override our instincts?
Once again, at the extreme ends of those instincts, we're just as impulsive as any other animal, but there is a degree to which humans can hit the manual override on our instincts. Perhaps that's a talent shared by other animals—elephants, dolphins, and whales come to mind—but it certainly isn't widespread. Maybe our cognitive strength is simply our ability to turn down the noise.