Figure 2.

Setup of the 50-kHz USV radial maze playback paradigm. (A) Elevated eight arm radial maze equipped with two ultrasonic microphones and two ultrasonic loudspeakers positioned opposite to each other (only one ultrasonic microphone and the active loudspeaker are shown). The rat's behavioral responses during playback of acoustic stimuli were recorded with a video camera positioned above the radial maze. (B) Schematic illustration of the radial maze, depicting area definitions to assess approach behavior, with arms close to the loudspeaker denoted as proximal, central arms as neutral, and opposite arms as distal. (C) Acoustic stimuli were presented by an ultrasonic loudspeaker (sampling rate: 192 kHz; 16 bit), with accurate playback of acoustic stimuli being confirmed by means of ultrasonic microphones. (D) Testing was performed under dim red light.