The Journal of Neuroscience, September 1, 2002, 22(17):7671-7679
Developmental Changes Underlying the Formation of the Specialized
Time Coding Circuits in Barn Owls (Tyto alba)
M. Fabiana
Kubke,
Dino P.
Massoglia, and
Catherine E.
Carr
Department of Biology, University of Maryland, College Park,
Maryland 20742
Barn owls are capable of great accuracy in detecting the interaural
time differences (ITDs) that underlie azimuthal sound localization.
They compute ITDs in a circuit in nucleus laminaris (NL) that is
reorganized with respect to birds like the chicken. The events that
lead to the reorganization of the barn owl NL take place during
embryonic development, shortly after the cochlear and laminaris nuclei
have differentiated morphologically. At first the developing owl's
auditory brainstem exhibits morphology reminiscent of that of the
developing chicken. Later, the two systems diverge, and the owl's
brainstem auditory nuclei undergo a secondary morphogenetic phase
during which NL dendrites retract, the laminar organization is lost,
and synapses are redistributed. These events lead to the restructuring
of the ITD coding circuit and the consequent reorganization of the
hindbrain map of ITDs and azimuthal space.
Key words:
avian development; morphogenesis; auditory; laminaris; evolution; interaural time difference
Copyright © 2002 Society for Neuroscience 0270-6474/02/22177671-09$05.00/0