Striatal and hippocampal contributions to flexible navigation in rats and humans

Abstract

The hippocampus has been firmly established as playing a crucial role in flexible navigation. Recent evidence suggests that dorsal striatum may also play an important role in such goal-directed behaviour in both rodents and humans. Across recent studies, activity in the caudate nucleus has been linked to forward planning and adaptation to changes in the environment. In particular, several human neuroimaging studies have found the caudate nucleus tracks information traditionally associated with that by the hippocampus. In this brief review, we examine this evidence and argue the dorsal striatum encodes the transition structure of the environment during flexible, goal-directed behaviour. We highlight that future research should explore the following: (1) Investigate neural responses during spatial navigation via a biophysically plausible framework explained by reinforcement learning models and (2) Observe the interaction between cortical areas and both the dorsal striatum and hippocampus during flexible navigation.

Keywords: Spatial navigation; dorsal striatum; flexible behaviour; goals; hippocampus; reinforcement learning; wayfinding.

Figure 1.

Dorsal striatum activity is correlated with the change in distance to goal at detours. (a) Replotted data from Javadi et al. (2019a) in which fMRI and virtual reality desert island riven with lava was used to examine the brain regions responsive to the change in distance to the goal at detours. Top row shows a zoomed in schematic from the larger virtual environment used and the transition that occurs when the path is unexpectedly blocked. Bottom row: the same change but from the first person perspective. Brain image shows bilateral activity in medial caudate nucleus (dorsal striatum) cluster-corrected for activity correlated positively with the parametrically modulated change in distance-to-goal. (b) Replotted data from Howard et al. (2014). In this study, a film simulation of Soho in London was used to test navigation, including accommodating detours. The amount of change in distance-to-goal caused by forced detours was correlated with the dorsal striatal activity. Red regions show regions activations thresholded at p < 0.005 uncorrected, shown in the mean structural image.