Figure 5.

Differences in neuronal responses to closed-loop and open-loop visual stimulation. Five minutes of closed-loop virtual behavior was followed by two replay runs, during which the recorded visual stimulus was played back in open-loop. In closed-loop, a period with drag (forward stimulus motion in the absence of swimming, simulating a backward water current) was followed by a period without drag (no stimulus motion in the absence of swimming). (A) Hindbrain anatomy, with neurons b and c marked in red. Scale bar: 100 μm. (B) Motor-related neuronal activity, with increased fluorescence signal during more vigorous swimming. Note that the behavior, as well as the neuronal activity, is different during closed-loop and open-loop replay, underlining the importance of closed-loop virtual behavior above simple open-loop stimulus presentation. Behavior, as also shown before (Ahrens et al., 2012), is qualitatively different in closed- and open-loop, with open-loop behavior often more vigorous (double arrows) than closed-loop behavior (single arrow). (C) Non-motor-related neuron activity that may be visually driven. Patterns of activity during closed- and open-loop are similar, but not identical, and bear no correlation to motor output (e.g., see replay 1). This suggests that this cell is driven by visual input, albeit in a non-trivial way.