Hey guys, Julia here for DNews Temperature is a measure of energy. How fast the molecules in something like an ice cube are moving. But how does the brain read that information? For scientists, it’s been a bit of mystery. But new research published in the journal Nature sheds a little light. The research looked at fruit fly brains to see how it responded to temperature. They identified three types of neurons that reacted. Two sets were what the researchers called “narrowly tuned”, they could detect either hot OR cold. One set of neurons let us know very quickly whether something was becoming hot or cold. Another set was a little slower, but traded accuracy for speed. These neurons could report temperature better. But in a surprise to the researchers there was a third set of neurons that was fast and “broadly tuned”, it responded quickly and could sense both hot and cold, possibly as a ‘mayday’ kind of signal. So that’s an idea of what might be going on in the brain. But how does the feeling get there? Well in humans, we take in a lot of our information through our somatosensory system. This is made up of things like nerve endings, touch receptors and receptors for temperature called Thermoreceptors which lie just under our skin. It’s thought that the mammalian nervous system has separate thermoreceptors in our skin for either warmth or cold. There are far more cold receptors beneath the skin than warm ones, and are more concentrated in areas like the nose and ears and the signals from cold receptors actually travel to the brain up to ten times faster than signals from warm receptors which is why those spots get so chilly so quickly. But some cold receptors respond when we touch something really hot, like over 113 degrees. Which is why sometimes the hot water in your show feels icy cold. This phenomenon, is called paradoxical cold. And scientists aren’t sure why, exactly. Weird, right? Anyways, these thermoreceptors on our skin send this information to our nerve cells in our spine, and this is where things get interesting.

The membranes surrounding these nerve cells have proteins that open and close in response to different temperatures. This allows charged particles to move from cell to cell, sending information up into our brains. Our body has dozens of these proteins, called Ion channels, allowing us to experience a wide range of temperatures. These channels can sometimes respond to things other than temperature, like food, pain or acidity. One of the channels called TRPV1, reacts to hot temperatures—about 100 degrees Fahrenheit. But it also responds to capsaicin, the thing that makes chili peppers so spicy, which is why our body tastes chili but senses heat. Another of these channels, TRPM8, is sensitive to cold. And guess what this channel also responds to? Yeah you guessed it menthol, which is the thing that makes mint seem cool. Speaking of hot and cold, have you ever wondered what your life would look like in thermal? our very good friends over at buzzfeedblue recently looked at some everyday situations as scene through a thermal camera! It was really weird and really beautiful. Check it out! It's the first link in the description if you are on your mobile phone. Alright guys, do you like it hot or cold? Let us know in the comments below. and while you’re at it hit those like and subscribe buttons and keep coming back here! we’ve got new episodes every day of the week.