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Information Geometry and Neural Netowrks
Shun-ichi Amari RIKEN Brain Science Institute Orthogonal decomposition of rates and (higher-order) correlations Synchronous firing and higher correlations Algebraic singularities caused by multiple stimuli Dynamics of learning in multiplayer perceptrons
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Dual Affine Connections
Information Geometry Systems Theory Information Theory Statistics Neural Networks Combinatorics Physics Information Sciences Math. AI Riemannian Manifold Dual Affine Connections Manifold of Probability Distributions
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Information Geometry ? Riemannian metric Dual affine connections
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Manifold of Probability Distributions
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Two Structures Riemannian metric and affine connection
Fisher information
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Riemannian Structure
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Affine Connection covariant derivative straight line
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Independent Distributions
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Neural Firing ----firing rate ----covariance higher-order correlations
orthogonal decomposition
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of Higher-Order Correlations
Information Geometry of Higher-Order Correlations ----orthogonal decomposition Riemannian metric dual affine connections Pythagoras theorem Dual geodesics
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Correlations of Neural Firing
firing rates correlations orthogonal coordinates
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0011000101101 0100100110100 0101101001010 firing rates: correlation—covariance?
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Independent Distributions
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Pythagoras Theorem p q r D[p:r] = D[p:q]+D[q:r] p,q: same marginals
correlations D[p:r] = D[p:q]+D[q:r] q r p,q: same marginals r,q: same correlations independent estimation correlation testing invariant under firing rates
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No pairwise correlations,
Triplewise correlation …… …… ……
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Pythagoras Decomposition of KL Divergence
only pairwise independent
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Higher-Order Correlations
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Synfiring and Higher-Order Correlations
Amari, Nakahara, Wu, Sakai
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Population and Synfire
Neurons
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Population and Synfire
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Synfiring
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r Bifurcation : independent---single delta peak pairwise correlated
higher-order correlation! r
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RIKEN Brain Science Institute
Field Theory of Population Coding Shun-ichi Amari RIKEN Brain Science Institute Collaborators: Si Wu Hiro Nakahara
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Population Coding and Neural Field
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Population Encoding x f (z-x) r(z) z
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Noise b
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Probability Model
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Fisher information Cramer-Rao
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Fourier Analysis
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Fisher Information
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Dynamics of Neural Fields
Shaping Detecting Decoding
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How the Brain Solves Singularity in Population Coding
S. Amari and H. Nakahara RIKEN Brain Science Institute
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Neural Activity
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Parameter Space
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synfiring resolves singularity
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synfiring mechanism common multiplicative noise
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S.Amari and H.Nagaoka, Methods of Information Geometry AMS &Oxford Univ Press, 2000
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Mathematical Neurons
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Multilayer Perceptrons
y
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Multilayer Perceptron
neuromanifold space of functions
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Neuromanifold Metrical structure Topological structure
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Riemannian manifold
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Geometry of singular model
W
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Gaussian mixture
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Topological Singularities
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singularities
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Singularity of MLP---example
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Backpropagation ---gradient learning
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Information Geometry of MLP
Natural Gradient Learning : S. Amari ; H.Y. Park
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y
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2 hidden-units
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Dynamics of Learning
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The teacher is on singularity
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The teacher is on singularity
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