Estimating Dimensionality of Neural Representations from Finite Samples

Fuente: arXiv
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Auteurs principaux: Chun, Chanwoo, Canatar, Abdulkadir, Chung, SueYeon, Lee, Daniel
Format: Preprint
Publié: 2025
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author Chun, Chanwoo
Canatar, Abdulkadir
Chung, SueYeon
Lee, Daniel
author_facet Chun, Chanwoo
Canatar, Abdulkadir
Chung, SueYeon
Lee, Daniel
contents The global dimensionality of a neural representation manifold provides rich insight into the computational process underlying both artificial and biological neural networks. However, all existing measures of global dimensionality are sensitive to the number of samples, i.e., the number of rows and columns of the sample matrix. We show that, in particular, the participation ratio of eigenvalues, a popular measure of global dimensionality, is highly biased with small sample sizes, and propose a bias-corrected estimator that is more accurate with finite samples and with noise. On synthetic data examples, we demonstrate that our estimator can recover the true known dimensionality. We apply our estimator to neural brain recordings, including calcium imaging, electrophysiological recordings, and fMRI data, and to the neural activations in a large language model and show our estimator is invariant to the sample size. Finally, our estimators can additionally be used to measure the local dimensionalities of curved neural manifolds by weighting the finite samples appropriately.
format Preprint
id arxiv_https___arxiv_org_abs_2509_26560
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Estimating Dimensionality of Neural Representations from Finite Samples
Chun, Chanwoo
Canatar, Abdulkadir
Chung, SueYeon
Lee, Daniel
Machine Learning
Neurons and Cognition
The global dimensionality of a neural representation manifold provides rich insight into the computational process underlying both artificial and biological neural networks. However, all existing measures of global dimensionality are sensitive to the number of samples, i.e., the number of rows and columns of the sample matrix. We show that, in particular, the participation ratio of eigenvalues, a popular measure of global dimensionality, is highly biased with small sample sizes, and propose a bias-corrected estimator that is more accurate with finite samples and with noise. On synthetic data examples, we demonstrate that our estimator can recover the true known dimensionality. We apply our estimator to neural brain recordings, including calcium imaging, electrophysiological recordings, and fMRI data, and to the neural activations in a large language model and show our estimator is invariant to the sample size. Finally, our estimators can additionally be used to measure the local dimensionalities of curved neural manifolds by weighting the finite samples appropriately.
title Estimating Dimensionality of Neural Representations from Finite Samples
topic Machine Learning
Neurons and Cognition
url https://arxiv.org/abs/2509.26560