Informative, Impossible, Impromptu, and Emotional: Expirimenting with the Untold Narratives of Science Through the Lens of Rodent Evidence Accumulation

Abstract

Evidence accumulation in rats has long been considered the domain of a region of the brain known as the Posterior Parietal Cortex (PPC). Studies have shown that activity in this region corresponds with evidence accumulation in both rats and monkeys in tasks like the Poisson Clicks task. This is a behavioral task in which rats must discern which of two speakers generate more auditory clicks. However, recent studies involving the inactivation of the PPC have demonstrated that performance in evidence accumulation tasks is not significantly hindered by inactivation. Even stranger, data from auditory, parametric, working memory tests show that a rat’s performance in evidence accumulation tasks may even be improved by PPC inactivation. Based on this new data, a reevaluation of our understanding of neural circuitry in evidence accumulation is needed. One likely solution is that PPC activity may correspond to previous trial effects. This could explain why activity in this region corresponds to evidence accumulation but does not provide useful information for the completion of the current task. Through logistic regression and psycometric curve analysis of an existing PPC data set, we show that previous trial effects appear to be linked to PPC activity.