Abstract
Sensing interaural time difference (ITD) is essential for azimuthal sound source localization. In birds, bilateral sound signals first converge in nucleus laminaris (NL). NL neurons act as a coincidence detector of bilateral excitatory synaptic inputs, and encode ITD. Thus, the accuracy of coincidence detection (CD) in NL neurons is critical for ITD calculation. NL neurons also receive GABAergic inputs, and these inhibitory innervations have been thought to improve the accuracy of CD in NL. GABAergic inputs for NL arise mainly from the superior olivary nucleus (SON) and partly from interneurons. SON neurons increase their activity with the increase of stimulus intensity, but poorly hold timing information. Thus, SON neurons are thought to have a role in gain control of NL neurons. On the other hand, interneurons have been proposed to possess a different role from SON neurons, however details are not known. In this study, we examined the difference between SON neurons and interneurons, in their roles for CD in NL. [J Physiol Sci. 2007;57 Suppl:S146]
