Male crickets attract females by producing species-specific chirps at a fixed frequency of about 4.5 kHz. Female crickets are specially tuned to this tone and are able to locate males purely based on auditory cues. The mechanisms behind directional hearing in crickets have been partly elucidated but major components remain ill understood.
The main principle behind directional hearing in crickets is a direct comparison of pressure fluctuations at the left and right 'ear'. Ears consist of a tympanum located on the front legs. Internally the space behind the tympani is connected by means of auditory tracheae. Pressure fluctuations therefore reach the tympanum directly as well as indirectly, from the other side of the body. Phase shifts between these two sources strongly modulate the tympanum-oscillations and hence support directional hearing.
We currently have several questions:
- What are the contributions from ipsi lateral and contra lateral sound pressure modulations on the tympanum?
- Which role does the medial septum play, which separates the auditory tracheae on both sides of the body?
- To hat extent do internal pressure modulations limit tympanum movements for ipsi lateral sounds?
- How are differences in tympanum oscillations translated into afferent neural activity?
- How is afferent information from left and right tympanum integrated to generate a directional signal?
To answer these questions we combine a modeling approach with new experimental measurements. Hereto we will build an experimental setup in which we can measure tympanum movements for sounds applied in different combinations on the left and right hand side of the body. In addition we will record single unit activity from the auditory nerve under comparable conditions.
Please contact Dr.I. M.J.M. Lankheet if you are interested.
|