Projects Prof Nowowtny

Sensory Adaptations in the Animal Kingdom

Sensory organs enable us to discriminate environmental signals. It fascinates me how sensory organs can be highly specialized and detect only a small range of the environmental signals but still ensure the survival of the animal. The study of these adaptations enables us to gain knowledge about the perception in general and the regulation of behaviour in particular. My working group investigates functions and adaptations of insect and mammalian ears. Especially, my work with insects provides the potential for the study of natural diversity of mating behaviour and sensory adaptation.

 

Evolution often leads to similar solutions - convergent evolution in hearing

To occupy different niches in an ecosystem, insects developed many different strategies to generate and percept acoustic signals. Recently, we discovered a tropical bushcricket that exhibits a sex-specific adaptation in their communication and ears (Scherberich et al., Current Biology 2016, see figure left). Unique in the animal kingdom, male bushcrickets of the species Ancylecha fenestrata have significant more sensory cells than females of the same species. Surprisingly, these additional cells in the male ears are used to over represent the area where the female call frequency is perceived. This phenomena of an auditory fovea was described so far only as an adaptation of pray (bats) and predator detection (mull) in mammals. 

 

 

 

 

 

Processing of sensory information in the ear

Ears not simply detect environmental signals and translate these into a neuronal correlate. By the processing in the ear, signals important for the animal are amplified or filtered. I started my studies in hearing by the investigation of these amplification processes in the mammalian ear and discovered a mechanism of direct fluid coupling between outer and inner hair cells (Nowotny and Gummer, PNAS 2006). In my group we continue this type of studies in insects and revealed a biomechanical filter mechanisms, which are important for the channel gating (Hummel et al. J. Neurosci, 2016, see figure below). One other surprising finding was that bushcrickets use travelling waves for frequency discrimination (Palghat Udayashankar et al. 2012 and 2015, see movies). These waves are comparable (wave propagation velocity and wave length) to travelling waves found in mammals. 

 


Funding:

The project is funded by the Deutsche Forschungsgemeinschaft (NO 841/1-1 and NO 841/2-1). Additional funding was provided by the Jürgen Manchot foundation and Goethe University by the project "Nachwuchswissenschaftler/innen im Fokus" 

 

Movies for download:

 

Mecopoda elongata 6kHz

Mecopoda elongata 18kHz

Mecopoda elongata 60kHz

Schistocera 4kHz

Schistocera 4kHz

 

Inner Ear Damages and the Generation of Tinnitus

The emergence of tinnitus after acoustic overstimulation and damage to the inner ear is an enormous psychological burden for patients. Exact causes of the resulting phantom noise are largely unknown. We suspect one reason for the initiation of the development of tinnitus in the signal transduction process and routing in the inner ear. Our experiments include the examination of the shift from acute to chronic tinnitus after acoustic overstimulation by using the startle reflex response in gerbils, rats and mice. We explore for example the question how noise-induced hearing loss and plasticity related changes in the brain shape tinnitus characteristics and found that the perceived frequency of tinnitus depends on the bandwidth of the applied noise trauma and the repetition of noise trauma.

 

Funding:
The project is funded by the Deutsche Forschungsgemeinschaft (NO 841/4-1) and the Adolf-Messer Stiftungspreis 2009.