# Factorised Hierarchical Successor Representation (fHSR)

In large environments at naturalistic scale, rat and bat hippocampal CA1 place cells often carry multiple irregularly spaced firing fields, whereas the classical single-scale successor representation holds only in small enclosures. The factorised hierarchical successor representation (fHSR) folds one-step actions together with subgoal-directed subroutines into a predictive map, then decomposes the maps of several tasks into a non-negative overcomplete basis that gives each model cell its tuning. On a 48 m rat track and a 200 m bat track the model reproduced the gamma-Poisson overdispersion of field counts, and it predicted a spatial periodicity of population activity whose wavelength is independent of track length, a prediction tested in rat data.

In large environments at naturalistic scale, rat and bat hippocampal CA1 place cells often carry multiple irregularly spaced firing fields, whereas the classical single-scale successor representation holds only in small enclosures. The factorised hierarchical successor representation (fHSR) folds one-step actions together with subgoal-directed subroutines into a predictive map, then decomposes the maps of several tasks into a non-negative overcomplete basis that gives each model cell its tuning. On a 48 m rat track and a 200 m bat track the model reproduced the gamma-Poisson overdispersion of field counts, and it predicted a spatial periodicity of population activity whose wavelength is independent of track length, a prediction tested in rat data.