Parallel cognitive maps for multiple knowledge structures in the hippocampal formation

Abstract

The hippocampal-entorhinal system uses cognitive maps to represent spatial knowledge and other types of relational information. However, objects can often be characterized by different types of relations simultaneously. How does the hippocampal formation handle the embedding of stimuli in multiple relational structures that differ vastly in their mode and timescale of acquisition? Does the hippocampal formation integrate different stimulus dimensions into one conjunctive map or is each dimension represented in a parallel map? Here, we reanalyzed human functional magnetic resonance imaging data from Garvert et al. (2017) that had previously revealed a map in the hippocampal formation coding for a newly learnt transition structure. Using functional magnetic resonance imaging adaptation analysis, we found that the degree of representational similarity in the bilateral hippocampus also decreased as a function of the semantic distance between presented objects. Importantly, while both map-like structures localized to the hippocampal formation, the semantic map was located in more posterior regions of the hippocampal formation than the transition structure and thus anatomically distinct. This finding supports the idea that the hippocampal-entorhinal system forms parallel cognitive maps that reflect the embedding of objects in diverse relational structures.

Scale-Dependent Coding of the Hippocampus in Relational Memory

“…To quantify the observation, we evaluated the fitness of a piecewise linear function to participants' behavioral performance, against various functions such as logistic, quadratic, logarithmic, and linear functions, using the coefficient of determination (� 2 ) as the metric. Consistent with the observation, the piecewise linear function showed the highest fitness to the behavioral performance Neur al cor r elates of memor y for mation and utilization Upon identifying two distinct memory states in the RM task, we further replicated previous research (Sullivan Giovanello et al, 2004;Olson et al, 2006;Hannula et al, 2006;Giovanello et al, 2009;Schwarb et al, 2016;Zheng et al, 2024) demonstrating hippocampal activation in relational integration using representational similarity analysis (RSA; Kriegeskorte et al, 2006) and functional connectivity (FC) approaches.…”

“…Upon identifying two distinct memory states in the RM task, we further replicated previous research (Sullivan Giovanello et al, 2004; Olson et al, 2006; Hannula et al, 2006; Giovanello et al, 2009; Schwarb et al, 2016; Zheng et al, 2024) demonstrating hippocampal activation in relational integration using representational similarity analysis (RSA; Kriegeskorte et al, 2006) and functional connectivity (FC) approaches. In the RSA analysis, we calculated the multivoxel patterns of HPC activity during the RM task for each trial and constructed a correlation coefficient matrix across trials for each voxel (see Methods).…”

“…Upon identifying two distinct memory states in the RM task, we further replicated previous research (Sullivan Giovanello et al, 2004;Olson et al, 2006;Hannula et al, 2006;Giovanello et al, 2009;Schwarb et al, 2016;Zheng et al, 2024) demonstrating hippocampal activation in relational integration using representational similarity analysis (RSA; Kriegeskorte et al, 2006) and functional connectivity (FC) approaches.…”