Functional laminar and columnar organization of the auditory centers in echolocating Japanese greater horseshoe bats.

During echolocation, bats coordinately employ the vocalization system to emit orientation sounds and the auditory system to hear returning echoes. The brain in these animals should be functionally organized to process such biologically significant sounds. Here we utilized the autoradiographic 2-deoxy-[14C]glucose (DG) method to visualize functional organization of the auditory centers of echolocating Japanese greater horseshoe bats, Rhinolophus ferrumequinum nippon. Autoradiographic color images made from the brains of echolocating bats revealed a functional laminar structure in the inferior colliculus. Furthermore, a functional columnar organization appeared in the auditory cortex during echolocation. These laminar and columnar organization were not observed in the brain of resting bats.