Figure 1: Self-initiated and uncued auditory target recognition.

(a) Schematic of the operant conditioning chamber with two nose ports (one for self-initiation and one for target response), one speaker and one food dispenser. (b) Schematic of the go/no-go auditory behavioural task. Target (red) and non-target (grey) tones were 100 ms in duration, distributed one octave apart between 0.5 and 32 kHz, and delivered in a random order at 70 dB SPL. For the uncued trials, the animals did not self-initiate; instead, the trials were programmed to start at pseudo-random inter-trial intervals between 6 and 10 s. (c) Performance on the wideband stimulus set. Left, individual performance of one animal over three consecutive sessions of self-initiated trials (filled circles, solid line) or uncued trials (open circles, dashed line). In red, target tone (4 kHz); other tones were unrewarded non-targets. Top right, summary of hit rates for all animals. Hit rate was higher during self-initiation than uncued trials. Each square represents one animal. Bottom right, summary of d′ values for all animals. Stimulus recognition was higher during self-initiation than uncued trials. Error bars indicate mean and s.e.m. in both dimensions. (d) Performance on the narrowband stimulus set. Left, example individual performance when the target and non-target stimuli were at smaller perceptual distances from each other. Red, target tone (4 kHz). Filled circles and solid line, self-initiated trials. Empty circles and dashed line, uncued trials. Top right: summary plots showing hit rates for all rats during ‘Self’ and ‘Uncued’ trials. Bottom right: summary plots showing d′ values for all rats. (e) Performance on the detection task. Top left: example hit rates to the target frequency at different sound levels. Filled circles and solid line: self-initiated trials. Empty circles and dashed line: uncued trials. Shaded area represents responses to tones played below the background noise level (30–40 dB). Top right: the false alarm rate remained relatively low at all sound levels. Bottom: d′ values calculated for each tone level. Right: summary data showing d′ values for four rats. (f) behavioural performance when the stimuli were delivered via headphones. Left: example individual performance when the stimuli were presented via headphones. Right: summary plots showing performance for all rats with headphones during self-initiated and uncued trials. Error bars are s.e.m.