Readout of a spatial memory by interruption of ramping activity in the retrohippocampal cortex

Neurons in the retrohippocampal cortices play crucial roles in spatial memory. Many retrohippocampal neurons have firing fields associated with specific locations, but whether this is the sole strategy for representing spatial memories is unclear. Here, we demonstrate that during a spatial memory task retrohippocampal neurons also encode location through ramping activity within discrete regions of a track, with rewarded locations represented by offsets or switches in the slope of the ramping activity. These representations do not require cues that mark reward locations indicating that they result from recall of the track structure. Similar representations emerged in recurrent neural networks trained to navigate to a rewarded location. We hypothesize that retrohippocampal ramping activity and its interruption mediates readout of learned models for goal-directed navigation.