Figure 2. Photostimulation in freely moving mice performing a detection task.
(a) Schematic of the photostimulation setup (see Methods). (b) Schematic of the behavioral apparatus and reward contingencies. The mouse initiates a trial by sticking its snout into the central port. Photostimuli are applied during a stimulation period (300 ms) accompanied by a series of bright blue light flashes delivered to the behavioral arena (30Hz, 300ms) to mask possible scattered light from the portable light source. The mouse then decides to enter either the left or the right port for a water reward. If a photostimulus was present, the choice of the left port was rewarded with a drop of water (hit, green star) whereas the choice of the right port lead to a short timeout (4 sec, miss, red star). If the stimulus was absent only the choice of the right port was rewarded with reward (correct reject, green circle) whereas the left port lead to a timeout (4 sec, false alarm, red circle). (c) Data from one session (200 trials) with a single stimulus (1 ms) with decreasing light intensities. Each horizontal line delineates 20 trials at fixed light intensity. Blue dots indicate the presence or absence of a photostimulus. Stimulated and non-stimulated trials were presented pseudo-randomly with a probability of 0.5.