Adaptation changes directional sensitivity in a visual motion-sensitive neuron of the fly.

The blowfly visual system is a well-suited model to investigate the functional consequences of adaptation. Similar to cortical motion-sensitive neurons, fly tangential cells are directional selective and adapt during prolonged stimulation. Here we demonstrate in a tangential cell large changes in directionality after adaptation with motion in one direction. Surprisingly, depending on stimulation parameters, sensitivity for motion in the adapted direction relative to the unadapted direction can be either enhanced or attenuated. A simple model reproduces our results. It only incorporates previously identified changes in contrast sensitivity with motion adaptation. Thus, novel forms of motion adaptation seem unnecessary.