Extended Data Fig. 2: The structure of the representational map in the auditory cortex predicts stimulus generalization in a go/no-go task as well as in classical conditioning.

a. Grand averaged representational similarity matrix and corresponding dimension-reduced classical Multidimensional scaling (cMDS) display constructed from the dataset acquired in the current study during baseline (n = 29 mice, 3 imaging days). b. Schematic of a go/no-go sound discrimination paradigm from a previous study¹², in which the same set of sound stimuli was used as in the current study. In well-trained mice, licking behavior was measured in response to reinforced S+ and S- stimuli. In addition, spontaneous behavioral categorization of non-reinforced off-target stimuli was used as an estimate of perceptual similarity of a given off-target in relation to the pair of target stimuli. c. Schematic of the application of the neurometric similarity matrix to estimate perceptual distances. The length of each side in the triangle of off-target, and reinforced stimuli S1 and S2 is determined by the correlation coefficients. The estimated relative representational similarity of the off-target stimulus to S1 or S2 is defined as the internal dividing point in the line connecting S1 and S2, orthogonally mapped from the off-target point. d. Solid black line: Behaviorally evaluated perceptual similarity as the go probability of off-target sounds in go no-go behavioral task (mean ± s.d. across mice, n = 12; the data replotted from Bathellier et al., 2012). Blue dots: Prediction of perceptual similarity from the representational similarity matrix in a with the metric in b. r and p indicates Pearson correlation and its p-value between the behavioral go probability and the prediction from the similarity matrix. SSE indicates Sum of squared errors of the similarity matrix-based prediction from the behavioral go probability. e. Stimulus generalization to conditioned and non-conditioned sound stimuli from another previously published study¹³, in which the same set of 34 sound stimuli as in the current study was used. One of the stimuli was used as a conditioned stimulus (CS) in a classical auditory-cued fear conditioning paradigm and was paired with a foot shock (US). Four days after conditioning, a generalization test was performed by presenting the CS and the three nonCS sounds (I, II, and III), without foot shock. The conditioned mice exhibited freezing behavior to CS, nonCS-I nonCS-II, but not to nonCS-III. f. Dimension-reduced display of the representational map obtained in the current study shown in a. Dot diameters depict a measure of neuronal plasticity (increased likelihood of a given sound stimulus to activate the same neuron assembly as the CS) obtained in the previous study¹³. Note, that the proximity between nonCS stimuli and the CS in the representational map allows us to predict the degree of plasticity in sound responses in the auditory cortex as well as the level of behaviorally measured stimulus generalization.