Brain has a noise-canceling circuit, team says
A team of scientists has uncovered the neural processes mice use to ignore their own footsteps, a discovery that offers new insights into how we learn to speak and play music.
The “ability to ignore one’s own footsteps requires the brain to store and recall memories and to make some pretty stellar computations,” explains David Schneider, an assistant professor at New York University’s Center for Neural Science and one of the paper’s lead authors. “These are the building blocks for other, more important sound-generating behaviors, like recognizing the sounds you make when learning how to speak or to play a musical instrument.”
The research, conducted at Duke University’s School of Medicine, centered on an intuition -- that we are usually unaware of the sound of our own footsteps -- as a vehicle for understanding larger neural phenomena: how this behavior reveals the ability to monitor, recognize, and remember the sound of one’s own movements in relation to those of their larger environments.
The “capacity to anticipate and discriminate these movement-related sounds from environmental sounds is critical to normal hearing,” Schneider explains. “But how the brain learns to anticipate the sounds resulting from our movements remains largely unknown.”
To explore this, Schneider and his colleagues, Janani Sundararajan and Richard Mooney at Duke’s School of Medicine, designed an “acoustic virtual reality system” for the mice. Here, the scientists controlled the sounds the mice made walking on a treadmill while monitoring the animals’ neural activity, allowing them to identify the neural circuit mechanisms that learn to suppress movement-related sounds.
Overall, they found a flexibility in neural function -- the mice developed an adjustable “sensory filter” that allowed them to ignore the sounds of their own footsteps. In turn, this allowed them to better detect other sounds arising from their surroundings.