Acuity of spatial origin of sounds

Scientists discover origin of a giant synapse

May 28, 2013

The calyx of Held (orange) is a type of giant synapse, which synapses onto “medial nucleus of the trapezoid body” (MNTB) neurons (green) and relays excitatory information to these neurons. The neurons in turn send inhibitory outputs to a number of targets in the auditory brain stem and thus act as a master source of well-timed inhibition for the lower auditory system. (Credit: University of Colorado School of Medicine)

EPFL scientists have revealed a mechanism responsible for the creation of giant synapses in the brain that allow us to efficiently process auditory information.

Humans and most mammals can determine the spatial origin of sounds with remarkable acuity. To accomplish this small daily miracle, the brain has developed a circuit that’s rapid enough to detect the tiny lag that occurs between the moment the auditory information reaches one of our ears, and the moment it reaches the other.

The mastermind of this circuit is the “Calyx of Held,” the largest known synapse in the brain. EPFL scientists have revealed the role that a certain protein plays in initiating the growth of these giant synapses. The discovery, could also help shed light on a number of neuropsychiatric disorders.

Enormous synapses enable faster auditory-related communication/.../