The Spatial Similarity Task: A cross-species approach to spatial memory

Memory serves as the cornerstone of cognitive function and specifically enables the critical ability to disambiguate and encode similar experiences as distinct memories. Mnemonic discrimination of near spaces and places is a process crucially underpinned by a computational feature of the hippocampus, pattern separation. Whereas this refined aspect of spatial memory has been addressed in abundance in the rodent literature, fewer spatial tasks are designed to specifically query memory for spatial similarities in human subjects. To address this, we introduce an open-source virtual maze suite developed on the Unity platform, freely available for researchers to use, modify, and extend. The suite is designed to bridge the behavioral translation gap by assessing mnemonic discrimination in humans through a spatial delayed match-to-sample task, carefully modeled after rodent spatial memory tasks. Rather than relying on fully immersive systems, the suite leverages desktop-based virtual navigation to combine parametric control of experimental conditions with the ability to collect each participant's exploratory data. The pilot experiments are presented to validate the final suite design, alongside providing representative results from a subset of participants. Mnemonic discrimination was measured by parametric manipulation of spatial distances, resulting in a spatial distance memory function in which participants made more errors in remembering the correct location amongst similar or adjacent locations relative to distant locations. Given the prevalence of spatial memory deficits in age-related cognitive decline and neurological and psychiatric conditions, and the widespread use of spatial tasks in rodent models of these disorders, the Spatial Similarity Task (SST) suite offers a translationally grounded tool with direct potential for customization towards clinical application.