The hippocampal-entorhinal circuit is part of a network of areas involved in the encoding and retrieval of representations of distinct spatial environments and episodes. We explored the complexity of neural activity patterns (‘dimensionality’), to understand how multiple maps are maintained in sub-populations of neurons. High dimensionality suggests unique neural 'maps' for different environments, while low dimensionality indicates overlapping representations across episodes. Prior research has shown distinct spatial representations in hippocampal subfields CA1/ CA3, with increased dimensionality correlating with the number of environments. However, in neighboring brain structures, head direction and grid cell populations maintain consistent low-dimensional activity across environments/states. Our study focuses on the subiculum (SUB), a key intermediary between the high-dimensional hippocampus and the low-dimensional medial entorhinal cortex (MEC). We use simultaneous high-density electrophysiological recordings (Neuropixels 2.0 probes) in rats across the MEC, hippocampal CA1/CA3, and SUB as a rat explores several different environments, both familiar and novel. By applying novel ensemble detection algorithms, we identify sub-populations and examine how SUB neurons, known for complex remapping, align with hippocampal and entorhinal dynamics. Our preliminary findings show that the dimensionality of combined neural activity patterns increases proportionally with the degree of place-cell remapping. This happens to a higher degree in CA1/CA3 than SUB. Notably, the activity patterns of sub-populations of neurons tend to evolve towards a lower-dimensional state space from CA1 through SUB to MEC. This suggests a spectrum of network-level representations: highly unique patterns in CA1, intermediate states in SUB, and more generalizable patterns in MEC.