Context-dependent stimulus presentation to freely moving animals in 3D.

The presentation of controllable, dynamic sensory stimuli provides a powerful experimental paradigm, which has been extensively applied to explore sensory processing in walking and tethered flying insects. Recent advances in computer hardware and software technology provide the opportunity to track the 3D flight path of free-flying insects and process these data in real-time, opening up the possibility to present dynamic stimuli to free-flying animals. To accommodate for the increased complexity relating to 3D space, we partitioned experimental design, real-time data acquisition and stimulus control into multiple self-contained modules. 3D experimental scenarios were created in a stand-alone application by forging multiple 3D space-stimulus relationships. The use of dynamic cues is illustrated by an experiment, in which dynamic acoustic cues were presented to a free-flying parasitoid fly in a large 3D environment. The combination of loosely coupled modules provides robust and flexible solutions, allowing new paradigms to be readily implemented based on existing technologies. We demonstrate this with a test system that displayed a complex visual stimulus, controlled in real-time by the 2D position and orientation of a test object. The presented methods are applicable in a variety of novel experimental paradigms, including learning paradigms, for various sensory modalities in walking, swimming and flying animals.