Emergence of Lie Symmetries in Functional Architectures Learned by CNNs

In this paper we study the spontaneous development of symmetries in the early layers of a Convolutional Neural Network (CNN) during learning on natural images. Our architecture is built in such a way to mimic some properties of the early stages of biological visual systems. In particular, it contain...

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Autores principales: Federico Bertoni, Noemi Montobbio, Alessandro Sarti, Giovanna Citti
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Publicado: Frontiers Media S.A. 2021
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spelling oai:doaj.org-article:b4104313267940bdbb1857785f4373142021-11-22T06:40:15ZEmergence of Lie Symmetries in Functional Architectures Learned by CNNs1662-518810.3389/fncom.2021.694505https://doaj.org/article/b4104313267940bdbb1857785f4373142021-11-01T00:00:00Zhttps://www.frontiersin.org/articles/10.3389/fncom.2021.694505/fullhttps://doaj.org/toc/1662-5188In this paper we study the spontaneous development of symmetries in the early layers of a Convolutional Neural Network (CNN) during learning on natural images. Our architecture is built in such a way to mimic some properties of the early stages of biological visual systems. In particular, it contains a pre-filtering step ℓ0 defined in analogy with the Lateral Geniculate Nucleus (LGN). Moreover, the first convolutional layer is equipped with lateral connections defined as a propagation driven by a learned connectivity kernel, in analogy with the horizontal connectivity of the primary visual cortex (V1). We first show that the ℓ0 filter evolves during the training to reach a radially symmetric pattern well approximated by a Laplacian of Gaussian (LoG), which is a well-known model of the receptive profiles of LGN cells. In line with previous works on CNNs, the learned convolutional filters in the first layer can be approximated by Gabor functions, in agreement with well-established models for the receptive profiles of V1 simple cells. Here, we focus on the geometric properties of the learned lateral connectivity kernel of this layer, showing the emergence of orientation selectivity w.r.t. the tuning of the learned filters. We also examine the short-range connectivity and association fields induced by this connectivity kernel, and show qualitative and quantitative comparisons with known group-based models of V1 horizontal connections. These geometric properties arise spontaneously during the training of the CNN architecture, analogously to the emergence of symmetries in visual systems thanks to brain plasticity driven by external stimuli.Federico BertoniFederico BertoniFederico BertoniNoemi MontobbioAlessandro SartiGiovanna CittiGiovanna CittiFrontiers Media S.A.articlelie symmetriesCNN-convolutional neural networkprimary visual cortex (V1)lateral connectionlateral geniculatesub-Riemannian geometriesNeurosciences. Biological psychiatry. NeuropsychiatryRC321-571ENFrontiers in Computational Neuroscience, Vol 15 (2021)
institution DOAJ
collection DOAJ
language EN
topic lie symmetries
CNN-convolutional neural network
primary visual cortex (V1)
lateral connection
lateral geniculate
sub-Riemannian geometries
Neurosciences. Biological psychiatry. Neuropsychiatry
RC321-571
spellingShingle lie symmetries
CNN-convolutional neural network
primary visual cortex (V1)
lateral connection
lateral geniculate
sub-Riemannian geometries
Neurosciences. Biological psychiatry. Neuropsychiatry
RC321-571
Federico Bertoni
Federico Bertoni
Federico Bertoni
Noemi Montobbio
Alessandro Sarti
Giovanna Citti
Giovanna Citti
Emergence of Lie Symmetries in Functional Architectures Learned by CNNs
description In this paper we study the spontaneous development of symmetries in the early layers of a Convolutional Neural Network (CNN) during learning on natural images. Our architecture is built in such a way to mimic some properties of the early stages of biological visual systems. In particular, it contains a pre-filtering step ℓ0 defined in analogy with the Lateral Geniculate Nucleus (LGN). Moreover, the first convolutional layer is equipped with lateral connections defined as a propagation driven by a learned connectivity kernel, in analogy with the horizontal connectivity of the primary visual cortex (V1). We first show that the ℓ0 filter evolves during the training to reach a radially symmetric pattern well approximated by a Laplacian of Gaussian (LoG), which is a well-known model of the receptive profiles of LGN cells. In line with previous works on CNNs, the learned convolutional filters in the first layer can be approximated by Gabor functions, in agreement with well-established models for the receptive profiles of V1 simple cells. Here, we focus on the geometric properties of the learned lateral connectivity kernel of this layer, showing the emergence of orientation selectivity w.r.t. the tuning of the learned filters. We also examine the short-range connectivity and association fields induced by this connectivity kernel, and show qualitative and quantitative comparisons with known group-based models of V1 horizontal connections. These geometric properties arise spontaneously during the training of the CNN architecture, analogously to the emergence of symmetries in visual systems thanks to brain plasticity driven by external stimuli.
format article
author Federico Bertoni
Federico Bertoni
Federico Bertoni
Noemi Montobbio
Alessandro Sarti
Giovanna Citti
Giovanna Citti
author_facet Federico Bertoni
Federico Bertoni
Federico Bertoni
Noemi Montobbio
Alessandro Sarti
Giovanna Citti
Giovanna Citti
author_sort Federico Bertoni
title Emergence of Lie Symmetries in Functional Architectures Learned by CNNs
title_short Emergence of Lie Symmetries in Functional Architectures Learned by CNNs
title_full Emergence of Lie Symmetries in Functional Architectures Learned by CNNs
title_fullStr Emergence of Lie Symmetries in Functional Architectures Learned by CNNs
title_full_unstemmed Emergence of Lie Symmetries in Functional Architectures Learned by CNNs
title_sort emergence of lie symmetries in functional architectures learned by cnns
publisher Frontiers Media S.A.
publishDate 2021
url https://doaj.org/article/b4104313267940bdbb1857785f437314
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