FIGURE 1.

Training apparatus and task design. (A) Mice were positioned in the training apparatus with their heads fixed and their body in a body holder. Visual stimuli were presented on a screen located in front of the right eye, auditory stimulation was delivered through a speaker next to the screen. An infra-red beam in front of the mouth enabled the detection of licks. A reward spout, which was out of reach during most of the trial, was moved toward the mouse’s mouth at times reward was dispensed. (B) A trial started with an inter-trial interval (ITI) during which a gray isoluminant screen was shown. Following the ITI, visual, auditory or audiovisual stimuli were presented. (C) During task acquisition mice were trained to respond to visual and auditory stimuli (no audiovisual stimuli) which typically took 15–20 days after which task performance was on average above the performance criterion of d′ = 1.5 (dashed gray line). Mice responded with more fidelity to auditory compared to visual stimuli as indicated by a significantly higher d-prime (gray lines above plot indicate significant differences, Matched Pairs Signed Rank Test, p < 0.05).