Figure 4. Behavioral detection of midbrain photostimulation is similar across pulse rates and opsin types.

(a) Detection abilities were tested with an avoidance paradigm where mice crossed from one side of a shuttlebox to another to avoid receiving an electric shock (top). Crossing during the 5 s cue period was scored as a hit while crossing during an equivalent 5 s period during the intertrial interval (ITI) was scored as a false positive (FP, bottom). (b,c) Hit and FP probabilities are plotted as function of sound level (b) and laser amplitude (c) across all pulse rates for a single, representative mouse. (d–g) The slope of the linear fit applied to each psychometric function obtained with acoustic (d) and laser (f) stimulation provides an objective readout for salience of pulse rate detection. Behavioral d’ is calculated from the acoustic (e) and laser (g) stimulation level that supports a 50% hit probability for each pulse rate.