Paranoid has 1 rod photoreceptor that it uses to navigate its environment.
It uses two interneurons and two motor neurons to do so, but the two sides of the circuit are connected a bit differently.
The light output on the rod drives both wheels forward, while the dark output drives just the left wheel backward. This results in a NeuroBuggy that follows the edge of a light halo.
Video from NeuroTinker. Open this build on YouTube