In the Drosophila flight simulator, a single fly, glued to a small
hook of silver wire and attached to a torque meter, is flying stationarily
in the center of a cylindrical panorama (arena). In the flight simulator
mode (closed loop), the rotational speed of the arena is made proportional
to the fly's recorded yaw torque around its vertical body axis. This enables
the fly to stabilize the rotational movements of the panorama (i.e. to
fly straight) and to adjust certain flight directions with respect to particular
visual landmarks. Yaw torque and flight direction of the fly are recorded
continuously and stored in the computer memory (sampling frequency 20 Hz).
Originally, the flight simulator has been employed for detailed examination
of Drosophila's visual orientation behaviour (reviewed in Heisenberg
M., Wolf R., 1993: "The sensory-motor link in motion-dependent flight
control of flies." Rev Oculomot Res. 5: 265-83).
Combined with reinforcement, the setup changes into an operant conditioning
paradigm in which the fly learns to control the appearance of a reinforcer
(e.g. beam of infrared light) by its choice of flight direction with respect
to the angular positions of visual patterns at the arena wall.
Reinhard Wolf in the Behavioral
Physiology Group has also designed a classical conditioning procedure
that uses the same conditioned response and a similar conditioned stimulus
as the operant one. In the classical training procedure the flight simulator
mode is interrupted (open loop) and the panorama is kept stationary with
one pattern type in front of the fly. After 3s the panorama is rotated
by 90o in 220ms, bringing the other pattern type into the frontal position.
One of the two orientations is combined with the reinforcer. In both procedures
learning is tested in the same way: The apparatus is switched to the flight
simulator mode and the fly's pattern preference is recorded whithout reinforcement. |
