Abstract
Decisions are driven by the coordinated activity of diverse neural populations. Inhibitory neurons play a critical role in decision-making models, but technical challenges have left untested their role in vivo, both in novice and expert decision-makers. To understand the contribution of excitatory and inhibitory neurons to decision-making, we simultaneously measured their activity in mice judging the repetition rate of multisensory pulses. Individual inhibitory neurons were slightly more selective and more strongly correlated than excitatory neurons. Further, inhibitory ensemble activity could be decoded to predict trial-by-trial choice with similar accuracy as excitatory ensembles. Finally, population activity in both cell types changed in parallel as mice transitioned from novice to expert decision-makers: population activity gradually became more choice-selective and prompt. The observations advocate for models in which excitatory and inhibitory connectivity (1) preserves choice selectivity in both populations and (2) is fine-tuned with experience to support expert decision-making.