Visualizing Representational Dynamics with Multidimensional Scaling Alignment
This work addresses a methodological gap in neuroscience and AI for researchers studying representational geometry dynamics, though it appears incremental as it builds on existing RSA frameworks.
The authors tackled the problem of analyzing and visualizing representational dynamics over time in brain activity and deep neural networks, using RDM movies and Procrustes-aligned Multidimensional Scaling (pMDS) applied to monkey IT cortex data, finding that object categorization may be hierarchical, multi-staged, and oscillatory.
Representational similarity analysis (RSA) has been shown to be an effective framework to characterize brain-activity profiles and deep neural network activations as representational geometry by computing the pairwise distances of the response patterns as a representational dissimilarity matrix (RDM). However, how to properly analyze and visualize the representational geometry as dynamics over the time course from stimulus onset to offset is not well understood. In this work, we formulated the pipeline to understand representational dynamics with RDM movies and Procrustes-aligned Multidimensional Scaling (pMDS), and applied it to neural recording of monkey IT cortex. Our results suggest that the the multidimensional scaling alignment can genuinely capture the dynamics of the category-specific representation spaces with multiple visualization possibilities, and that object categorization may be hierarchical, multi-staged, and oscillatory (or recurrent).