Jack July

A neural circuit that localizes sound:

Employing imperfect tools and tasked with a dynamic sensory landscape, neural circuits often rely on elegant architecture to extract information from the environment.

As a sound source moves around the head, the timing difference of sound arrival at each ear changes. Birds have an array of neurons in their brainstem that detect coincident activity from both ears, such that a sound in front of the bird arrives at the array with the same delay from each ear, while an off-center sound has an asymmetrical delay between the ears that shifts the between-ear coincidence to a different part of the array. The bird reads the timing difference in the array as an azimuthal location. Above, the coincidence-detectors, which segregate information from each ear into top or bottom branches.