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Information Geometry and Neural Netowrks

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Presentation on theme: "Information Geometry and Neural Netowrks"— Presentation transcript:

1 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

2 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

3 Information Geometry ? Riemannian metric Dual affine connections

4 Manifold of Probability Distributions

5 Two Structures Riemannian metric and affine connection
Fisher information

6 Riemannian Structure

7 Affine Connection covariant derivative straight line

8 Independent Distributions

9 Neural Firing ----firing rate ----covariance higher-order correlations
orthogonal decomposition

10 of Higher-Order Correlations
Information Geometry of Higher-Order Correlations ----orthogonal decomposition Riemannian metric dual affine connections Pythagoras theorem Dual geodesics

11 Correlations of Neural Firing
firing rates correlations orthogonal coordinates

12    0011000101101 0100100110100 0101101001010 firing rates: correlation—covariance?

13 Independent Distributions

14 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

15 No pairwise correlations,
Triplewise correlation …… …… ……

16 Pythagoras Decomposition of KL Divergence
only pairwise independent

17 Higher-Order Correlations

18 Synfiring and Higher-Order Correlations
Amari, Nakahara, Wu, Sakai

19 Population and Synfire
Neurons

20 Population and Synfire

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24 Synfiring

25 r Bifurcation : independent---single delta peak pairwise correlated
higher-order correlation! r

26 RIKEN Brain Science Institute
Field Theory of Population Coding Shun-ichi Amari RIKEN Brain Science Institute Collaborators: Si Wu  Hiro Nakahara

27 Population Coding and Neural Field

28 Population Encoding x f (z-x) r(z) z

29 Noise b

30 Probability Model

31 Fisher information Cramer-Rao

32 Fourier Analysis

33 Fisher Information

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35 Dynamics of Neural Fields
Shaping Detecting Decoding

36 How the Brain Solves Singularity in Population Coding
S. Amari and H. Nakahara RIKEN Brain Science Institute

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38 Neural Activity

39 Parameter Space

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44 synfiring resolves singularity

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46 synfiring mechanism common multiplicative noise

47 S.Amari and H.Nagaoka, Methods of Information Geometry AMS &Oxford Univ Press, 2000

48 Mathematical Neurons

49 Multilayer Perceptrons

50 Multilayer Perceptron
neuromanifold space of functions

51 Neuromanifold Metrical structure Topological structure

52 Riemannian manifold

53 Geometry of singular model

54 Gaussian mixture

55 Topological Singularities

56 singularities

57 Singularity of MLP---example

58 Backpropagation ---gradient learning

59 Information Geometry of MLP
Natural Gradient Learning : S. Amari ; H.Y. Park

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62 2 hidden-units

63 Dynamics of Learning

64 The teacher is on singularity

65 The teacher is on singularity

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