Ascending Auditory Pathways in the Brain Stem of the Bat, Pteronotus parnellii

Abstract

Although mammalian echolocation has been extensively studied in recent years, little is known concerning the connections of neural centers which might be involved in the special auditory functions of echolocation. We have mapped the ascending auditory pathways from cochlear nucleus in the bat, Pteronotus parnellii parnellii (Gray), using techniques for tracing axonally transported molecules (³H leucine or horseradish peroxidase) in the anterograde or retrograde directions. Our principal observations concern (1) direct pathways from cochlear nucleus to the central nucleus of the inferior colliculus and (2) an indirect pathway which relays within the lateral lemniscus enroute from cochlear nucleus to the central nucleus of the inferior colliculus.