2. Behavioral Biology TALKS - Deutsche Zoologische Gesellschaft

consistently arranged with double-rows of somata rather than a linear sequence. This
arrangement of neurons is found for 30-50% of the overall auditory receptors.
Occasionally, dendrites of distal receptors also alternate, or occur massed with no
obvious ordering. A double row of receptors and their scolopales is probably more
common among Tettigoniidae than previously appreciated. With respect to
functional implications, the massed dendrites of distal cells may not allow for a clear
frequency discrimination, but could imply similar tuning characteristics.
����168 Philipp Tellers
Response Variability in Broadband Neurons of the Barn Owl Auditory Pathway
Authors: Philipp Tellers 1 , Kerstin Bülles 1 , Hermann Wagner 1
Affiliation: 1 Institute for Biology II, RWTH-Aachen
Barn owls use differences in the time of arrival between the two ears (ITDs) to
localize sound sources in azimuth. At the early levels of the auditory pathway ITDs are
processed in narrow band frequency channels. This processing leads to phase
ambiguities. Phase ambiguities preclude the determination of the real sound source
position and have therefore to be solved. The acoustic system accomplishes this by
across-frequency integration in the external nucleus of the inferior colliculus (IC).
In 2006 Christianson and Pena (J Neurosci 26: 5948) hypothesized that the auditory
system of the barn owl uses the step from nucleus laminaris (NL), where ITDs are
detected, to the core of central nucleus of the IC (ICCc) for improving the ITD coding.
Noise delay functions of ICCc neurons exhibited a lower variability and a higher peakto-trough
ratio than their NL pendants. We hypothesize that the highly accurate ITD
coding is less important for the auditory system upstream of ICCc, resulting, for
example in higher response variability. To test our hypothesis, we recorded
extracellularly from single units in the external nucleus of the IC (ICx) and the
auditory arcopallium (AAr), a forebrain nucleus. Preliminary data support our
hypothesis: noise delay functions of ICx and AAr neurons are less stable over
repetitions and exhibit lower peak-to-trough ratios compared to ICCc neurons.
����169 Vincent van Meir
Electrophysiological correlates of vocal plasticity in singing canaries
Authors: Vincent van Meir 1 , Manfred Gahr 1
Affiliation: 1 Max Planck Institute for Ornithology, Seewiesen
Telemetric electrophysiological measurements in singing canaries can provide new
insight on how the production of complex vocal sequences is achieved by the brain.
The song behavior of canaries differs substantially from the main model species for
this type of research: the zebra finch. Canaries produce long songs containing trills
and long syllables with stable and variable spectral and temporal features. The
stability of the song production can change in adulthood dependent on light cycle
and hormone levels.
Using lightweight transmitters we recorded electrical activity in awake, freely moving
animals for up to two weeks after the implantation of an electrode. We recorded
mainly from HVC, a telencephalic region with a central role in the production and
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