Dynamikbereichsadaptation bei chronischem Tinnitus
Klinische Psychiatrie, Psychotherapie und Kinder- und Jugendspychiatrie
Zusammenfassung der Projektergebnisse
The level of acoustic signals varies over the range of approx. 120-140 dB. The dynamic range of auditory system neurons is between 20 and 40 dB. “Dynamic range adaptation” refers to the way the auditory system handles the conflict between sensitivity and accuracy arising from this mismatch by dynamically adjusting the response range of single neurons. In the course of the project, six experiments focussing on different aspects of dynamic range adaptation were completed. The first experiment showed that the Pa component of the auditory middle latency response in Heschl’s sulcus mirrored dynamic range adaptation: Stimulus level was either high or low in fixed blocks and alternated randomly between high and low in roving blocks. The response amplitude difference between roving high and low was larger than the difference between fixed high and low. Later components of the middle latency response showed the opposite pattern, presumably reflecting a counterregulatory effort. In the second experiment, the steady-state auditory evoked magnetic field was recorded. An amplitude-modulated tone was presented continuously. Every ~2.1 s the stimulus ramped up or down in level. This experiment demonstrated a response amplitude overshoot effect following ascending ramps and an amplitude undershoot effect after descending ramps. In the third experiment, the SSR was recorded in tinnitus sufferers and healthy controls matched for age, sex, stimulated ear, and hearing loss. The overshoot effect was weaker and the undershoot effect was stronger in patients than healthy controls. In a GLM analysis, this difference remained significant when GÜF and HQ questionnaire scores were entered as covariates. The fourth experiment showed an interaction of the effects of stimulus microstructure (damped vs. ramped modulation periods, with “damped” referring to sudden attack and gradual decay and “ramped” referring to the opposite) and macrostructure (the alternation of high and low stimulus level) on the steady-state response over- and undershoot effect.The damped overshoot was significantly larger than the ramped overshoot in the increasing condition, whereas damped and ramped undershoot did not differ significantly. The fifth experiment recorded the auditory N1m to investigate the adaptation to tone pulse trains. High (H) and low level (L) pulse trains were presented. H and L trains differed in N1m amplitude, but the first response of H-trains was not larger and the first response to L- trains was not smaller than the respective successor responses. The sixth experiment has also been completed, however the data remain to be analyzed.
Projektbezogene Publikationen (Auswahl)
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Auditory evoked magnetic field signatures of dynamic range adaptation of level coding: relevance to tinnitus and hyperacusis. 9th International TRI Tinnitus Conference. Tinnitus: From Cochlea to Brain and Back. June 7-10, 2015, Ann Arbor, Michigan, USA
A. Hassel, M. Andermann, B. Cramer, H. Riedel, A. Rupp, E. Diesch
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Tinnitus: Psychische und physiologische Faktoren. Deutsche Gesellschaft für Audiologie e. V. 19. Jahrestagung. March 9-12, 2016, Hannover, Germany
Elisabeth Wallhäusser-Franke, Eugen Diesch
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Auditory evoked magnetic field signatures of dynamic range adaptation of sound level coding in tinnitus patients and healthy controls. 1st World Tinnitus Congress, XII International Tinnitus Seminar. May 22-24, 2017, Warsaw, Poland
A. Hassel, B. Cramer, C. Hattendorf, S. Heiland, A. Rupp, E. Diesch
