You might never have thought about it before, but 99% of the time you’re walking around, you don’t hear the sound of your own footsteps.
The other 1% of the time, something is different – your shoes are wet, you’re wearing heels on a hard floor, etc. – and guess what magical organ you have in your body that makes this happen?
1. Ever wonder why you don't usually hear your own footsteps? Why you're not surprised by the sound of your keyboard while typing? Or how you can (sometimes) ignore the sound of your keys jangling in your pocket?
Probably not. But @janani_ss and I did! pic.twitter.com/rVgLGS0jOi
— David Schneider (@schneiderneuro) September 12, 2018
That’s right – your brain is your own personal noise canceling headphones. It also works to cancel the sound of your own breathing and chewing, ensuring that you don’t go insane all at once. Scientists aren’t sure exactly how the brain knows to ignore these sounds, or how it’s able to guess when they’re coming.
Recently, Duke and NYU researchers hooked mice up to treadmills in order to try to better understand, and got back some interesting data.
I put mice on a treadmill #gainz pic.twitter.com/jCvVXmQgxS
— BLM (@WerdnAOfficial1) August 1, 2019
The mice ran on treadmills while hooked up to an augmented reality system that allowed the team to control the sounds the mice heard. They played specific tones that matched the tempo of their steps in an attempt to “push the mouse’s brain beyond what it was evolved to do.”
4. That last step is called a prediction! And we wanted to figure out how the brain does it.
So we created an augmented reality (AR) system where we could control the sounds mice heard while running. And we studied their brain before, during and after AR experience. pic.twitter.com/gW3oiJxAxH
— David Schneider (@schneiderneuro) September 12, 2018
After a few days in the system, the mice’s brains stopped responding to the artificial tones, but only while they were running. They were even able to watch the noise filter build up in the neurons to reach that point.
Basically, the mice’s brains learned the artificial footstep tone, then turned on the noise-canceling neurons that were tuned to that sound while it listened for noises that weren’t related to running.
In fact, their brains got even better at hearing non-running sounds after a while.
“For mice, who are prey animals, this ability to ignore the sounds they make probably allows them to better detect other sounds – like a cat who might be stalking them while they’re running over dried leaves,” one of the authors wrote on Twitter.
They’re also thinking that the data could help explain some facets of memory, and how our brains use them to predict the future.
Which is all pretty darn cool, when you think about it.
So… what do you think about all this? Let us know in the comments!
