Spatial Learning in Drosophila
In addition to being a Howard Hughes Medical Institute investigator and a faculty member in the Columbia University Biochemistry and Neuroscience departments, Dr. Zuker was also a Senior Fellow at the Janelia Farm Research Campus. In collaboration with Michael Reiser at Janelia Farm, two MD/Ph.D. students from the Zuker lab and Columbia’s MSTP program have studied the place learning capabilities of the fruit fly Drosophila melanogaster (19). While many insects use visual landmarks to precisely locate their nest, prey, or foraging area, the extent to which flies use vision to navigate and remember specific locations had been unclear. Using a suite of molecular and genetic tools available in the fruit fly, combined with a novel virtual reality behavioral arena, we explored visually guided navigation to help elucidate how an insect knows where it is, and where it is going.
VIDEO: Place learning in the thermal-visual arena
The floor of the arena is composed of 64 thermoelectric modules (a Peltier array), the panorama is provided by a 24 × 192 light-emitting-diode (LED) display and flies are recorded using a camera under infrared (IR) illumination.
The movie (played at 25x recorded rate) shows all flies during training trials 1-10 in a representative coupled experiment. The movie highlights the position of each fly, with its center (dots) and trajectories (lines) in one of 6 colors; the lengths of the tracks denote a 4 s window. The yellow box indicates the borders of the lone “cooled tile”. See paper for details (19). Top right: Diagram illustrating the displayed visual panorama (gray and green) and the location of the cool spot (blue square). Note that even as the absolute position of the cool spot changes between trials its location relative to the visual panorama remains constant (coupled condition). Bottom right: Median time to reach the cool tile (red dot) is shown. For each trial, data is plotted after >90% of the flies reach the cool spot. Note the dramatic improvement in the time to reach the safe spot as the flies learn its location (i.e. between trials 1 and 3). This improvement is due to flies taking shorter and more direct paths to the target rather than simply increasing walking speed