Fig. 4: Challenged drinking improved or maintained cue representation in non-compulsive rats, but weakened cue representation strength in compulsive rats.

a Cue representation was examined by comparing pre-CS+ to CS+ time epochs (CS+ onset representation) and CS+ to CS− time epochs (CS+/− discrimination representation). b PC trajectories for pre-CS+ the time window did not vary for many PCs, consistent with a lack of stimulation or consistent time-locked behavior across trials. Conversely, CS+ onset produced a moving trajectory. (−1 (green dot) to +1.9 s relative to CS+ onset. Yellow dashed sections: CS+ onset epoch (see c).) c PC separation between pre-CS+ and CS+ time epochs. d Mean PC separation across the CS+ onset epoch (c, yellow epoch) showed that representation strength increased with challenged drinking (quinine) for non-compulsive rats, but decreased for compulsive rats. e Trajectories on both CS+ and CS− trials moved quickly from the pre-CS location near the start of the CS, but CS- trials quickly returned towards their original position. (−2 (green dot) to +4 s relative to CS+ onset. Yellow sections: CS+/− epoch (see f).) f PC separation between CS+ and CS− trials. Oscillations seemed to correspond to the on/off cycle of the blinking/solid light modality used for the CS+/− that was counter-balanced across animals. g Mean PC separation during the CS +/− epoch (f yellow time window) showed that CS+/− representation strength was unchanged in non-compulsive rats during challenge, but decreased in compulsive rats. b, e: mean trajectory, all neurons, only the 3 PCs with large separation effect size shown for clarity. c and f: mean +/− std across PCA subsample trials, only neurons from a given experimental group, all seven stable PCs. d and g: Mean +/− std across mean PC separation values from each 0.1 s time bin (N = 20) in CS+ onset or CS+/− epoch, ***: p < 10⁻³. Source data are provided as a Source Data file.