An Important Step toward Understanding the Role of Body-based Cues on Human Spatial Memory for Large-Scale Environments

Derek J Huffman,Arne D Ekstrom

doi:10.1162/jocn_a_01653

Derek J Huffman, Arne D Ekstrom

Open Access

https://doi.org/10.1162/jocn_a_01653

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Abstract

Moving our body through space is fundamental to human navigation; however, technical and physical limitations have hindered our ability to study the role of these body-based cues experimentally. We recently designed an experiment using novel immersive virtual-reality technology, which allowed us to tightly control the availability of body-based cues to determine how these cues influence human spatial memory [Huffman, D. J., & Ekstrom, A. D. A modality-independent network underlies the retrieval of large-scale spatial environments in the human brain. Neuron, 104, 611-622, 2019]. Our analysis of behavior and fMRI data revealed a similar pattern of results across a range of body-based cues conditions, thus suggesting that participants likely relied primarily on vision to form and retrieve abstract, holistic representations of the large-scale environments in our experiment. We ended our paper by discussing a number of caveats and future directions for research on the role of body-based cues in human spatial memory. Here, we reiterate and expand on this discussion, and we use a commentary in this issue by A. Steel, C. E. Robertson, and J. S. Taube (Current promises and limitations of combined virtual reality and functional magnetic resonance imaging research in humans: A commentary on Huffman and Ekstrom (2019). Journal of Cognitive Neuroscience, 2020) as a helpful discussion point regarding some of the questions that we think will be the most interesting in the coming years. We highlight the exciting possibility of taking a more naturalistic approach to study the behavior, cognition, and neuroscience of navigation. Moreover, we share the hope that researchers who study navigation in humans and nonhuman animals will synergize to provide more rapid advancements in our understanding of cognition and the brain.

Highlights

Robertson, and Taube (2020) discuss one important issue when considering modeling real-world navigation in the laboratory: how we account for body movements in navigation experiments that use virtual reality (VR)
They critiqued one of our recent papers (Huffman & Ekstrom, 2019a) in which we showed that the spatial representations of well-learned environments were similar across a range of body-based cue conditions
Steel et al (2020) challenged the validity of our approach by arguing that (1) the use of immersive VR is unnatural, (2) our results are limited because we did not find a difference in behavioral performance during fMRI scanning, (3) our behavioral tasks did not adequately assess spatial representations, and (4) our theoretical aims

Summary

INTRODUCTION

One of the major issues in cognitive neuroscience involves relating neural signals to the types of behaviors we encounter during real-world situations, such as navigating to our local supermarket to find our favorite foods. Steel, Robertson, and Taube (2020) discuss one important issue when considering modeling real-world navigation in the laboratory: how we account for body movements in navigation experiments that use virtual reality (VR). They reported evidence of border cells and of remapping of place cells between similar environments These cellular findings in rodents clearly cannot speak directly to our study in humans involving fMRI, these findings suggest that if similar mechanisms are at play in their apparatus in rats and in our apparatus in humans, we might expect that our enriched condition on the treadmill would reveal similar spatial representations to real-world navigation in the human brain. Place cells, head-direction cells, grid cells, and border cells (among others) could potentially contribute to the structure of spatial knowledge, that is, an underlying metric that allows animals to navigate (e.g., Moser & Moser, 2008) This leads to an important question: How do we reconcile the seemingly disparate views of heuristic-based behavior and the seemingly metric-like representations in the brain (Figure 2)? What is the relationship between laboratory-based experiments in the rodent (e.g., random foraging within a 1 m × 1 m open arena) and ecologically valid, largescale navigation under naturalistic behavioral demands (cf. Wehner, 2020, Chapter 7; Jacobs & Menzel, 2014)?

Conclusion

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