In a study just published in the premier journal Nature, co-authors Runyan, Piasini, Panzeri & Harvey asked how the brain decides where a sound is coming from.
Dr. Stefano Panzeri, a computational biologist from the Istituto Italiano di Tecnologia, has collaborated with Chris Harvey, a faculty member in our department, who uses optical signals to watch neurons process information in real time as a mouse thinks. Panzeri then uses sophisticated statistical methods to understand how the correlated activity of dozens of neurons is related to the thinking.
Input from the two ears is combined in the brain, and subtle differences in the sound—which ear hears a louder sound, and which ear hears it first—are used to make that decision. In this study, mice ran in a virtual-reality maze and chose a direction based on where a sound came from. The authors found that activity in the auditory area of the brain was not that well correlated as mice decided where the sound came from, but activity in a higher-order processing area was well correlated, helping the higher-order area to retain the information longer. This research has implications for how humans listen to a single speaker in a noisy room.