AUDITORY AND VESTIBULAR SYSTEMSA GABAergic component in the commissure of the inferior colliculus in ratHernández, Olgaa b; Rees, Adrianc; Malmierca, Manuel S.a bAuthor Information aAuditory Neurophysiology Unit, Laboratory for the Neurobiology of Hearing, Institute for Neuroscience of Castilla y León bFaculty of Medicine, University of Salamanca, Salamanca, Spain cSchool of Neurology, Neurobiology and Psychiatry, The Medical School, Newcastle upon Tyne, UK Correspondence and requests for reprints to Professor Manuel S. Malmierca, MD, PhD, Faculty of Medicine, University of Salamanca, campus Miguel de Unamuno, Salamanca 37007, Spain Tel: +34923294563; fax: +34923294549; e-mail: [email protected] Sponsorship: This study was supported by grants from the DGES (BFI-2003-09147-02-01) and JCYL-UE (SA040/04) to M.S.M., and The Wellcome Trust (066348) to A.R., and M.S.M. and O.H. held a fellowship from the Spanish MCYT (FP-2000-5811). Received 14 June 2006; accepted 11 July 2006 NeuroReport: October 23, 2006 - Volume 17 - Issue 15 - p 1611-1614 doi: 10.1097/01.wnr.0000236857.70715.be Buy Metrics Abstract The commissure of the inferior colliculus is significant as the final point of interconnection between homologous structures on the two sides of the auditory pathway at the subcortical level. The presence of excitatory fibres is well established in this tract, but the existence of an inhibitory component is controversial. Using rats, we injected biotinylated dextran amine into the inferior colliculus on one side to retrogradely label cells projecting through the commissure from the contralateral inferior colliculus. Immunocytochemistry for γ-amino-n-butyric acid in neighbouring semithin sections revealed that 20% of biotinylated dextran amine cell profiles were also labelled for γ-amino-n-butyric acid. We conclude that monosynaptic inhibitory connections contribute to the inhibition observed in the contralateral inferior colliculus in functional studies of the commissural projection. © 2006 Lippincott Williams & Wilkins, Inc.