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Bayesian Brain
Presented by Nguyen Duc Thang
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Contents
Introduction Bottom-up approach Top-down approach Vision recognition, brain computer interface
(BCI), and artificial general intelligence (AGI)
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Introduction
Old dream of all philosophers and more recently of AI: understand how the brain
works make intelligent machines
T. Poggio “Visual recognition in primates and machines”, NIPS’07 tutorial
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Bayes rule
K. Kording “Decision Theory: What "Should" the Nervous System Do?”, Science 26 Oct. 2007
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Bayes rule
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Free energy and brain
Any adaptive change in the brain will minimize the free-energy, this is correspondent to Bayesian inference process: make prediction about the world and update based on what it senses
Friston K., Stephan KE. “Free energy and the brain”, Synthese, 2007
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Two approaches of Bayesian brain Bottom-up approach
How the brain works? Top-down approach
Machine intelligence When two approaches meet together?
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Bottom-up approach
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Bayesian population code
- Single neural: the spike counts satisfy the Poisson distribution
- A group of neural: decode the stimulus by Gaussian distribution
Ma W.J.,Beck J., Latham P., Pouget A. “Bayesian inference with probabilistic population codes”, Nature Neuroscience, 2006
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Bayesian inference
Beck J., Ma W.J., Kiani R., Hanks T., Churchland A.K., Roitman L. , Shadlen M.N., Latham P., Pouget A. “Probabilistic population codes for Bayesian decision making ”, Neuron, 2008
Sum of two population codes is equivalent to taking the product of their encoded distributions
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Blue brain project
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Top-down approach
Machine intelligence Is based on the Bayes theorem, build a
probabilistic framework for one specific problem, and apply Bayesian inference to find solutions
Bayesian inference: belief propagation, variational method, and non-parametric method
Some journals: IJCV, PAMI, CVIU, JMLR
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Interesting results
Automatically discover structure form, ontology, causal relationships
Kemp C., Tenenbaum J. B. “The discovery of structural form”, PNAS 2008
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Related researches
Vision recognition Brain computer interface (BCI) Artificial general intelligence (AGI)
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David Hunter Hubel (born February 27, 1926) was co-recipient with Torsten Wiesel of the 1981 Nobel Prize in Physiology or Medicine, for their discoveries concerning information processing in the visual system
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Vision recognition
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Classify animal and non-animal
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Results
Serre T., Oliva A., Poggio T. “A feedforward architecture accounts for rapid categorization”, PNAS 2007
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What is next: beyond the feedforward models
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Hierarchy Bayesian inference
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Brain-Computer interface (BCI) A brain–computer interface (BCI), sometimes called a direct neural interface or a
brain–machine interface, is a direct communication pathway between a brain and an external devices
Invasive BCI: direct brain implants restore sight for blindness, hand-control for persons with paralysis
Non-invasive BCI: EEG, MEG, MRI Interesting results: research developed in the Advanced Telecommunications (ATR)
Computational Neuroscience LAB in Kyoto, Japan allowed the scientists to reconstruct images directly from the brain and display them on a computer.
Miyawaki Y., “Decoding the mind’s eye-visual image reconstruction from human brain activity using a combination of multiscale local image decoders”, Neuron Dec.2008
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Artificial General Intelligence (Strong AI) Weak AI only claims that machines can act
intelligently. Strong AI claims that a machine that acts intelligently also has mind and understands in the same sense people do
More information on the AGI conference 2009 Prediction: singularity in 2045 Two different opinions
I, robot (2004) Eagle eye (2008) Cyborg girl (2008) Doraemon
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My opinion