Research projectEfferent modulation of auditory computation in echolocating bats and gerbils
The mammalian inner ear receives strong efferent neuronal projections from brainstem neurons that modulate auditory processing of this sense organ depending on central auditory processing stages. The functional characteristics of the efferent modulations are largely unknown. In the present work I want to investigate efferent function by measuring otoacoustic emissions in an auditory specialist, the echolocating bat Carollia perspicillata in comparison to a generalist, the mongolian gerbil (Meriones unguiculatus). Otoacoustic emissions are actively generated by sensory hair cells in the inner ear and allow a noninvasive assessment of their function. The efferent system can be activated by contralateral sound stimulation. Therefore echolocation callsignal components of the bat or communication signals from the gerbil will be used as efferent stimuli. A methodologically important step in the intended experiments is to reversibly block the efferent system by use of the volatile anaesthetic isoflurane. In addition, neuronal characteristics will be obtained from the cochlear nucleus, the first processing stage of the auditory system which is also known to receive efferent inputs. With these experiments I intend to extract behavioural relevant efferent signal computation mechanisms.
Döbler, S. ; Föller, E. ; Kössl, M. (2006):