Methods
                                                                 
 
There are no specific neuroethological methods. To study the neuronal basis of behaviour, several methods from different areas are employed, i.e. behavioural analysis, anatomical-morphological examinations, electrophysiology and electronics. In the following, the different methods will be shortly introduced.
  
                                                                 

 

 Faculty of Biology 
 Welcome
 Research
        - Animals
        - Methods
        - Projects

 Staff
 Publications
 Teaching
 Contact 
 Links

The main method used in the AG Neuroethology is the electromyogramm (EMG). Microelectrodes (~ 50 µm thick) are implanted into the muscles of the examined animal, and the muscle potentials of the moving animal are recorded.

 
                                                               
 
Electromyogramm of wing muscle M129 of a tethered desert locust  
         

To correlate the muscle activity with the movements, the animals are filmed simultaneously (normal VHS or High-Speed-videosystem).
         
It is not easy to generate controlled, consistent movements. Therefore, we are using several different techniques.
         

Treadmill

As the simplest procedure, we test the animals' normal walking behaviour. For the examination of the normal leg movement, the animals are put on a treadmill. The moving treadmill stimulates the locust to walk. The speed can be adjusted to keep the animal within a certain space.
               
       
               
In contrast to the analysis of walking animals and their leg movement, it is much more difficult to observe and analyse flying locusts. Therefore special instruments and techniques are needed, two of them are employed in the AG Neuroethology:
               

Tethered flight

The animals are tethered in a wind tunnel so that an air stream results in an unfolding of the wings ans stimulates the locusts to fly. The wind tunnel can be adjusted to wind velocities ranging from 0.5 m/s to 4.0 m/s. Various velocities are used to test different reactions to varying environments.
               
         
   
Tethered flight of a desert locust      
The wind tunnel of the AG Neuroethology  
       

The tethered flight allows the most easy recordings of EMGs. The electrodes are inserted directly into the muscles, then the animals are placed into the wind tunnel and appropriate recordings can be carried out.
       

Free flight

It is obvious, that the tethered flight reduces possible reactions of the animal due to the limitation of movements. Therefore, experimental artefacts were often employed to represent natural behaviour responses. Consequently, the AG Neuroethology tries to analyse free flying locusts. For this purpose we designed a room which permits the locusts to fly around without any impediment. Several light sources are used to influence the animal's flight direction and give the opportunity to study flight manoeuvres and to investigate the influence of several parameters. The animals are set into motion manually (thrown into the room, they start flying immediately) or by using the locust-catapult, developed by Wolfram Kutsch in cooperation with the university's workshop.
             
The flight room in the university's cellar, in front the locust catapult.
                 

Locust catapult

The animals are placed in a catapult and launched. The moment they leave the catapult, the animals start to fly actively. Start direction and - speed can be easily controlled and modified. By using the catapult, the initial start phase of every flight can be controlled and repeated.
                       
Angle, velocity and direction of the start can be held constantly using the catapult. The picture shows a prototype.  
     
Telemetrics  

Obviously, the recording of EMGs during free flight is impossible when using cables and electrodes connected directly to the measurement units. To record EMGs during free flight, we use radiotelemetrics. A small transmitter is glued on the animals tergum, the transmitter can modulate the electric signals and broadcast them to the surroundings. Similar to normal radio transmission, the signals can be picked up by a receiver. Miniaturisation allows to place several systems on one animal (roach: 4 transmitters, locusts 2 transmitters) and to transmit the electric activity via more than one channel.

The transmitters are constructed by hand using a stereomicroscope. A more advanced system could be established using computerchips, but so far, the financial investment is still too large to create appropriate microchips.
   
 
One of the transmitters developed and used in Konstanz. Scale 5 mm   Gromphadorhina portentosa with 4-channel-transmitter.  
     
 
A locust started manually initially flies through the dark room towards a white wall. There it will detect another light source next to the wall and consequently turn right. In the front, the high speed videosystem is seen, on the left the central computer unit.