Jaro Journal of the Association For Research in Otolaryngology, Mar 1, 2004
Gap detection using broadband noise was characterized in a group of young gerbils from the breedi... more Gap detection using broadband noise was characterized in a group of young gerbils from the breeding colony of the University of Regensburg (RB gerbils), old RB gerbils, and old gerbils from the breeding colony of the University of South Carolina (SC gerbils). Data from old RB and old SC gerbils were not significantly different and were subsequently combined for a comparison with data from the group of young RB gerbils. Level dependence of gap-detection thresholds in young and old domesticated gerbils resembled the typical mammalian pattern of level dependence. Gap-detection thresholds of old gerbils were significantly elevated at 30 dB SL and 50 dB SPL as compared with young gerbils. Compared with young gerbils tested at 30 dB SL and 50 dB SPL, the distribution of gap-detection thresholds in old gerbils was broader with a spread to higher gap-detection thresholds. Some old animals retained excellent temporal resolution, while some showed impaired gap detection. The gap-detection data collected in young and old gerbils resemble previously published data from humans of different age and confirm that gerbils are a useful model to study age-dependent changes in temporal processing.
The distribution of frequencies along the basilar papilla of the barn owl (Tyto alba) was studied... more The distribution of frequencies along the basilar papilla of the barn owl (Tyto alba) was studied by labelling small groups of primary auditory neurones of defined frequency response and tracing them to their peripheral innervation sites. The exact location of marked neurones was determined in cochlear wholemounts with the aid of a special surface preparation technique. The average basilar papilla
The basilar papilla length increases systematically with body mass for 41 species from more than ... more The basilar papilla length increases systematically with body mass for 41 species from more than 10 avian orders and this relation does not differ between phylogenetic groups. Audiograms of 25 nonstrigiform and 12 owl species, normalized relative to best frequency and best threshold, were used to compare audiogram shapes. The analysis revealed that the high frequency flank of the audiogram was remarkably similar across non-strigiform species. The high-frequency limit was on average 1.1 octaves above the best frequency, the low-frequency flank was less steep and showed much more species dependent variability. Audiogram shape in owls was much more variable. Morphological gradients along the basilar papilla revealed a small species dependent variability for the basal region of the basilar papilla and an increasing degree of variability towards the apex. In non-strigiform species, frequency selectivity for 2 and 4 kHz varied systematically with the space on the basilar papilla devoted to processing the corresponding frequency range. Space on the papilla did not vary systematically with frequency selectivity at 1 kHz. This difference between test frequencies might be related to the transition from electrical hair-cell tuning, that dominates below 1e2 kHz, to micromechanical tuning at higher frequencies.
... Symposium on Hearing Paterswolde, Netherlands, April 5-9, 1988 Edited by H. Duifhuis Biophysi... more ... Symposium on Hearing Paterswolde, Netherlands, April 5-9, 1988 Edited by H. Duifhuis Biophysics Department University of Groningen The Netherlands JW Horst and HP Wit Institute of Audiology University Hospital Groningen The Netherlands 1988 ...
Gap-detection thresholds were determined for single units in the cochlear ganglion and in auditor... more Gap-detection thresholds were determined for single units in the cochlear ganglion and in auditory nerve fibres of the starling from responses to two broadband noise bursts separated by a temporal gap of between 0.4 and 204.8 ms. All 35 units showed a threshold within the range of gap sizes tested. The median minimum-detectable gap was 12.8 ms with the minimum being 1.6 ms. A multiple regression analysis revealed that the size of the minimum-detectable gap was not significantly correlated with the neuron's CF, with its sharpness of tuning as given by its bandwidth 10 dB above threshold, or with its QIOdB value. Only the level of stimulation above the neuron's threshold showed a significant negative correlation with the size of the minimumdetectable gap. These results are discussed with respect to theoretical considerations of limits posed on temporal resolution by the characteristics of peripheral filters. These findings are also discussed in the context of the coding of gaps at different levels of the starling's auditory system and in relation to psychoacoustic results in the starling on gap detection and time resolution described by temporal modulation transfer functions.
Hintergrund und Fragestellung: Vor etwa 15 Jahren wurde erstmals im Innenohr von Vögeln der Ersat... more Hintergrund und Fragestellung: Vor etwa 15 Jahren wurde erstmals im Innenohr von Vögeln der Ersatz von Haarsinneszellen beobachtet. Seit-dem wird auch im menschlichen Innenohr nach Mecha-nismen gefahndet, die zur Wiederherstellung verlorener Funktionalität führen könnten. Bei Vögeln wurde gezeigt, dass sich neue Haarsinneszellen entweder durch direkte Transdifferenzierung von Stützzellen bilden oder Stütz-zellen in geschädigten Bereichen des Innenohrs wieder in den Zellzyklus eintreten, und die entstehenden Tochter-zellen dann das Potenzial haben zu neuen Haarsinneszelle oder Stützzellen heranzureifen (z.B. Cotanche, 1999). Solche Vorgänge konnten trotz vielfältiger Anstren-gungen bislang bei Säugern nicht nachgewiesen werden. Deshalb stellt sich die Frage ob und gegebenfalls in wel-chen Stadien der Entwicklung potenzielle Stamm-und/oder Vorläuferzellen im Innenohr von Säugern vor-handen sind. Obwohl auch im Gehirn nur ein sehr be-grenztes Regenerationspotential existiert, konnten i...
Aktuelle Forschungsergebnisse haben gezeigt, daß Vögel im Gegensatz zum Menschen und anderen Säug... more Aktuelle Forschungsergebnisse haben gezeigt, daß Vögel im Gegensatz zum Menschen und anderen Säugern die Fähigkeit besitzen, geschädigte Haarzellen in ihrem Hörogan zu ersetzen. Trotz der bei Vögeln nachgewiesenen cochleären Regenerationsfähigkeit wurde bereits vor einigen Jahren eine bestimmte Kanarienvogelrasse (Belgische Wasserschläger) beschrieben, welche eine erblich bedingte Schwellenerhöhung für Frequenzen oberhalb 2 kHz aufwies. Da die Tonaudiogramme bei diesen Tieren in Verhaltensversuchen bestimmt wurden, war die Ursache für die Schwellenerhöhung nicht klar. Wir haben deshalb physiologische und morphologische Untersuchungen des Hörorgans der Belgischen-Wasserschläger-Kanarienvögel (Serinus canarius) begonnen, um zu klären, ob eine cochleäre Störung vorliegt und ob diesen Tieren die Fähigkeit zur Regeneration von Haarzellen fehlt. Unsere Untersuchungen haben gezeigt, daß bei dieser Kanarienvogelrasse die meisten Haarzellen gravierende pathologische Veränderungen aufweisen. ...
Jaro Journal of the Association For Research in Otolaryngology, Mar 1, 2004
Gap detection using broadband noise was characterized in a group of young gerbils from the breedi... more Gap detection using broadband noise was characterized in a group of young gerbils from the breeding colony of the University of Regensburg (RB gerbils), old RB gerbils, and old gerbils from the breeding colony of the University of South Carolina (SC gerbils). Data from old RB and old SC gerbils were not significantly different and were subsequently combined for a comparison with data from the group of young RB gerbils. Level dependence of gap-detection thresholds in young and old domesticated gerbils resembled the typical mammalian pattern of level dependence. Gap-detection thresholds of old gerbils were significantly elevated at 30 dB SL and 50 dB SPL as compared with young gerbils. Compared with young gerbils tested at 30 dB SL and 50 dB SPL, the distribution of gap-detection thresholds in old gerbils was broader with a spread to higher gap-detection thresholds. Some old animals retained excellent temporal resolution, while some showed impaired gap detection. The gap-detection data collected in young and old gerbils resemble previously published data from humans of different age and confirm that gerbils are a useful model to study age-dependent changes in temporal processing.
The distribution of frequencies along the basilar papilla of the barn owl (Tyto alba) was studied... more The distribution of frequencies along the basilar papilla of the barn owl (Tyto alba) was studied by labelling small groups of primary auditory neurones of defined frequency response and tracing them to their peripheral innervation sites. The exact location of marked neurones was determined in cochlear wholemounts with the aid of a special surface preparation technique. The average basilar papilla
The basilar papilla length increases systematically with body mass for 41 species from more than ... more The basilar papilla length increases systematically with body mass for 41 species from more than 10 avian orders and this relation does not differ between phylogenetic groups. Audiograms of 25 nonstrigiform and 12 owl species, normalized relative to best frequency and best threshold, were used to compare audiogram shapes. The analysis revealed that the high frequency flank of the audiogram was remarkably similar across non-strigiform species. The high-frequency limit was on average 1.1 octaves above the best frequency, the low-frequency flank was less steep and showed much more species dependent variability. Audiogram shape in owls was much more variable. Morphological gradients along the basilar papilla revealed a small species dependent variability for the basal region of the basilar papilla and an increasing degree of variability towards the apex. In non-strigiform species, frequency selectivity for 2 and 4 kHz varied systematically with the space on the basilar papilla devoted to processing the corresponding frequency range. Space on the papilla did not vary systematically with frequency selectivity at 1 kHz. This difference between test frequencies might be related to the transition from electrical hair-cell tuning, that dominates below 1e2 kHz, to micromechanical tuning at higher frequencies.
... Symposium on Hearing Paterswolde, Netherlands, April 5-9, 1988 Edited by H. Duifhuis Biophysi... more ... Symposium on Hearing Paterswolde, Netherlands, April 5-9, 1988 Edited by H. Duifhuis Biophysics Department University of Groningen The Netherlands JW Horst and HP Wit Institute of Audiology University Hospital Groningen The Netherlands 1988 ...
Gap-detection thresholds were determined for single units in the cochlear ganglion and in auditor... more Gap-detection thresholds were determined for single units in the cochlear ganglion and in auditory nerve fibres of the starling from responses to two broadband noise bursts separated by a temporal gap of between 0.4 and 204.8 ms. All 35 units showed a threshold within the range of gap sizes tested. The median minimum-detectable gap was 12.8 ms with the minimum being 1.6 ms. A multiple regression analysis revealed that the size of the minimum-detectable gap was not significantly correlated with the neuron's CF, with its sharpness of tuning as given by its bandwidth 10 dB above threshold, or with its QIOdB value. Only the level of stimulation above the neuron's threshold showed a significant negative correlation with the size of the minimumdetectable gap. These results are discussed with respect to theoretical considerations of limits posed on temporal resolution by the characteristics of peripheral filters. These findings are also discussed in the context of the coding of gaps at different levels of the starling's auditory system and in relation to psychoacoustic results in the starling on gap detection and time resolution described by temporal modulation transfer functions.
Hintergrund und Fragestellung: Vor etwa 15 Jahren wurde erstmals im Innenohr von Vögeln der Ersat... more Hintergrund und Fragestellung: Vor etwa 15 Jahren wurde erstmals im Innenohr von Vögeln der Ersatz von Haarsinneszellen beobachtet. Seit-dem wird auch im menschlichen Innenohr nach Mecha-nismen gefahndet, die zur Wiederherstellung verlorener Funktionalität führen könnten. Bei Vögeln wurde gezeigt, dass sich neue Haarsinneszellen entweder durch direkte Transdifferenzierung von Stützzellen bilden oder Stütz-zellen in geschädigten Bereichen des Innenohrs wieder in den Zellzyklus eintreten, und die entstehenden Tochter-zellen dann das Potenzial haben zu neuen Haarsinneszelle oder Stützzellen heranzureifen (z.B. Cotanche, 1999). Solche Vorgänge konnten trotz vielfältiger Anstren-gungen bislang bei Säugern nicht nachgewiesen werden. Deshalb stellt sich die Frage ob und gegebenfalls in wel-chen Stadien der Entwicklung potenzielle Stamm-und/oder Vorläuferzellen im Innenohr von Säugern vor-handen sind. Obwohl auch im Gehirn nur ein sehr be-grenztes Regenerationspotential existiert, konnten i...
Aktuelle Forschungsergebnisse haben gezeigt, daß Vögel im Gegensatz zum Menschen und anderen Säug... more Aktuelle Forschungsergebnisse haben gezeigt, daß Vögel im Gegensatz zum Menschen und anderen Säugern die Fähigkeit besitzen, geschädigte Haarzellen in ihrem Hörogan zu ersetzen. Trotz der bei Vögeln nachgewiesenen cochleären Regenerationsfähigkeit wurde bereits vor einigen Jahren eine bestimmte Kanarienvogelrasse (Belgische Wasserschläger) beschrieben, welche eine erblich bedingte Schwellenerhöhung für Frequenzen oberhalb 2 kHz aufwies. Da die Tonaudiogramme bei diesen Tieren in Verhaltensversuchen bestimmt wurden, war die Ursache für die Schwellenerhöhung nicht klar. Wir haben deshalb physiologische und morphologische Untersuchungen des Hörorgans der Belgischen-Wasserschläger-Kanarienvögel (Serinus canarius) begonnen, um zu klären, ob eine cochleäre Störung vorliegt und ob diesen Tieren die Fähigkeit zur Regeneration von Haarzellen fehlt. Unsere Untersuchungen haben gezeigt, daß bei dieser Kanarienvogelrasse die meisten Haarzellen gravierende pathologische Veränderungen aufweisen. ...
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