Figure 1.

The 2-AFC spectra-spatial auditory discrimination task. A, Trial timing schematic. At the start of the trial, the rat hears an adaptor sequence followed by an interleaved target-distractor sequence of high-low pure tones (target, red; distractor, blue; 50 ms tone duration; 10 Hz joint repetition rate; 60 dB SPL amplitude). A 20 dB SPL amplitude drop in the target signals the opening of the 1 s response window. Early responses are neither rewarded nor punished. B, Stimulus configuration by paradigm type. In paradigm (i), no adaptor is present. The first stimulus heard by the rat is the target tone (played from either the left or the right speaker with random assignment on every trial), which is followed by the distractor tone from the opposite speaker with a 100 ms delay, resulting in an interleaved high-low tone sequence. The rat has to localize the target stimulus (the higher frequency of the pair) and to respond with a lick on the target side. In the adaptation paradigms, five tones of either the target frequency (ii) or the distractor frequency (iii) are presented simultaneously from both speakers for the first second of the trial before the onset of the interleaved sequence. The Target adapted paradigm (ii) is shown in (A).