2. Behavioral Biology TALKS - Deutsche Zoologische Gesellschaft

Sunday, September 23, 2012
Chair: James Poulet
�93 Christian Schopf A 701 / 12:00
Hearing in aging grey mouse lemurs (Microcebus murinus)
Authors: Christian Schopf 1 , Andrej Kral 1 , Julia Tünsmeyer 1 , Sabine B. R. Kästner 1 , Elke
Zimmermann 1
Affiliation: 1 Institute of Zoology, University of Veterinary Medicine Hannover,
Foundation, Hannover
Mouse lemurs are small nocturnal primates, communicating in the high-frequency
and ultrasonic range. They are discussed as an emerging new primate model for aging
and genomic research. The aim of this study was to gain first empirical information
on auditory thresholds and hearing sensitivity in mouse lemurs during aging. We
applied brainstem evoked response audiometry (BERA) a cost-efficient method
traditionally used for screening hearing sensitivity in human babies and animal
models in hearing research such as cats. To asses the effect of age, we determined
frequency dependent auditory thresholds in the range between 500 Hz and 100 kHz
of two age groups of mouse lemurs (young animals: 1 to 5 years of age; old animals: 6
years or older). Audiograms were established individually based on auditory
thresholds detected visually. Findings indicate that mouse lemurs show broadband
frequency sensitivity from 500 Hz to 80 kHz. Although they exhibit better hearing in
the ultrasonic range than most primates, their best frequency of hearing is about 8
kHz. High frequency hearing loss in the ultrasonic range was found in aged animals.
Long-term measurements will characterize the progress of that hearing loss more
exactly. For assessing hearing capabilities and deficiencies in small primates, such as
mouse lemurs, BERA is a promising, cost- and time-efficient technique.
�94 Alexander Fischer A 701 / 12:15
GABA - relevant for hearing cues?
Authors: Alexander Fischer 1 , Matthew Xu-Friedman 2 , Eckhard Friauf 1 , Désirée
Griesemer 1
Affiliations: 1 TU Kaiserslautern, Biology department, Animal physiology group;
2 University at Buffalo, Department of biological sciences
The brain utilizes subtle sound intensity and time differences between the two ears
to localize sound sources. We focus on the murine lateral superior olive (LSO), a
nucleus in the auditory brainstem, whose function is to integrate excitatory and
inhibitory signals for detection of interaural level differences. In rats and gerbils
inhibitory input to the LSO is mediated by GABA, together with glycine. To analyze
the specific role of GABA during development, whole-cell voltage-clamp recordings
were obtained from LSO principal neurons in acute brainstem slices around postnatal
days (P) 4 and 11. While electrical stimulation of inhibitory fibers in P4 mice revealed
~10% of inhibitory synaptic transmission to be mediated by GABA, we did not detect
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