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Hierarchical Temporal MemoryBio-inspired model of neocortex
Kristian Valentın
FMFI UK, UM SAV
kristian.valentin@fmph.uniba.sk
June 13, 2012
IntroductionNeocortex
Hierarchical Temporal Memory
Overview
1 IntroductionMotivationResearch GoalsTask of Visual Object Recognition
2 NeocortexCommon Cortical AlgorithmNeocortex
3 Hierarchical Temporal MemoryHistoryMemory-Prediction Theory of Brain FunctionHierarchical Temporal MemoryGoals
Kristian Valentın Hierarchical Temporal Memory
IntroductionNeocortex
Hierarchical Temporal Memory
MotivationResearch GoalsTask of Visual Object Recognition
Outline
1 IntroductionMotivationResearch GoalsTask of Visual Object Recognition
2 NeocortexCommon Cortical AlgorithmNeocortex
3 Hierarchical Temporal MemoryHistoryMemory-Prediction Theory of Brain FunctionHierarchical Temporal MemoryGoals
Kristian Valentın Hierarchical Temporal Memory
IntroductionNeocortex
Hierarchical Temporal Memory
MotivationResearch GoalsTask of Visual Object Recognition
Motivation
Interesting field of AI
Many possible applications
Finding out something about us
Kristian Valentın Hierarchical Temporal Memory
IntroductionNeocortex
Hierarchical Temporal Memory
MotivationResearch GoalsTask of Visual Object Recognition
Motivation
Interesting field of AI
Many possible applications
Finding out something about us
Kristian Valentın Hierarchical Temporal Memory
IntroductionNeocortex
Hierarchical Temporal Memory
MotivationResearch GoalsTask of Visual Object Recognition
Motivation
Interesting field of AI
Many possible applications
Finding out something about us
Kristian Valentın Hierarchical Temporal Memory
IntroductionNeocortex
Hierarchical Temporal Memory
MotivationResearch GoalsTask of Visual Object Recognition
Research Goals
Long-term goals
Build an object recognition system which enables to classify visualobjects in complex scenes
Short-term goal
Hierarchical Temporal Memory (HTM)
Current goal
Improve spatial and temporal learning methods (invariancy, speed ofconvergence)
Kristian Valentın Hierarchical Temporal Memory
IntroductionNeocortex
Hierarchical Temporal Memory
MotivationResearch GoalsTask of Visual Object Recognition
Research Goals
Long-term goals
Build an object recognition system which enables to classify visualobjects in complex scenes
Short-term goal
Hierarchical Temporal Memory (HTM)
Current goal
Improve spatial and temporal learning methods (invariancy, speed ofconvergence)
Kristian Valentın Hierarchical Temporal Memory
IntroductionNeocortex
Hierarchical Temporal Memory
MotivationResearch GoalsTask of Visual Object Recognition
Research Goals
Long-term goals
Build an object recognition system which enables to classify visualobjects in complex scenes
Short-term goal
Hierarchical Temporal Memory (HTM)
Current goal
Improve spatial and temporal learning methods (invariancy, speed ofconvergence)
Kristian Valentın Hierarchical Temporal Memory
IntroductionNeocortex
Hierarchical Temporal Memory
MotivationResearch GoalsTask of Visual Object Recognition
Task of Visual Object Recognition
Classification of an object in a visual scene
Invariant classification
scalepositionrotation
Kristian Valentın Hierarchical Temporal Memory
IntroductionNeocortex
Hierarchical Temporal Memory
MotivationResearch GoalsTask of Visual Object Recognition
Task of Visual Object RecognitionExample
Figure: (George, 2007)
Kristian Valentın Hierarchical Temporal Memory
IntroductionNeocortex
Hierarchical Temporal Memory
MotivationResearch GoalsTask of Visual Object Recognition
Similarity Measure: Euclidean distance
Figure: (George, 2007)
Kristian Valentın Hierarchical Temporal Memory
IntroductionNeocortex
Hierarchical Temporal Memory
MotivationResearch GoalsTask of Visual Object Recognition
Spatio-temporal Representation
Kristian Valentın Hierarchical Temporal Memory
IntroductionNeocortex
Hierarchical Temporal Memory
Common Cortical AlgorithmNeocortex
Outline
1 IntroductionMotivationResearch GoalsTask of Visual Object Recognition
2 NeocortexCommon Cortical AlgorithmNeocortex
3 Hierarchical Temporal MemoryHistoryMemory-Prediction Theory of Brain FunctionHierarchical Temporal MemoryGoals
Kristian Valentın Hierarchical Temporal Memory
IntroductionNeocortex
Hierarchical Temporal Memory
Common Cortical AlgorithmNeocortex
Common Cortical AlgorithmSupporting evidence
“Seeing in the Sound Zone,“ by Michael Merzenich, Nature, Vol.404, April 20, 2000, pp. 820-821.
”Induction of visual orientation modules in auditory cortex,“ byJitendra Sharma, Alessandra Angelucci and Mriganka Sur, Nature,Vol. 404, April 20, 2000, pp. 841-847
Kristian Valentın Hierarchical Temporal Memory
IntroductionNeocortex
Hierarchical Temporal Memory
Common Cortical AlgorithmNeocortex
Sensory Substitution
A sensorimotor account of vision and visual consciousness, KevinO’Regan and Alva Noe, 2001.Photograph courtesy: P. Bach-y-Rita
Kristian Valentın Hierarchical Temporal Memory
IntroductionNeocortex
Hierarchical Temporal Memory
Common Cortical AlgorithmNeocortex
Assumptions
Neocortex uses the same algorithm to learn different modalities
It learns efficiently
Kristian Valentın Hierarchical Temporal Memory
IntroductionNeocortex
Hierarchical Temporal Memory
Common Cortical AlgorithmNeocortex
No Free Lunch Theorem
No learning algorithm has an inherent superiority over otherlearning algorithms for all problems. (Wolpert, 1995)
An algorithm’s superiority comes from the assumptions that it makesabout the problem
Kristian Valentın Hierarchical Temporal Memory
IntroductionNeocortex
Hierarchical Temporal Memory
Common Cortical AlgorithmNeocortex
No Free Lunch Theorem
No learning algorithm has an inherent superiority over otherlearning algorithms for all problems. (Wolpert, 1995)
An algorithm’s superiority comes from the assumptions that it makesabout the problem
Kristian Valentın Hierarchical Temporal Memory
IntroductionNeocortex
Hierarchical Temporal Memory
Common Cortical AlgorithmNeocortex
Assumptions
Neocortex uses the same algorithm to learn different modalities
It learns efficiently
=>Data from different modalities must have the same underlyingstatistical structure
Kristian Valentın Hierarchical Temporal Memory
IntroductionNeocortex
Hierarchical Temporal Memory
Common Cortical AlgorithmNeocortex
Assumptions
Neocortex uses the same algorithm to learn different modalities
It learns efficiently
=>Data from different modalities must have the same underlyingstatistical structure
Kristian Valentın Hierarchical Temporal Memory
IntroductionNeocortex
Hierarchical Temporal Memory
Common Cortical AlgorithmNeocortex
Kristian Valentın Hierarchical Temporal Memory
IntroductionNeocortex
Hierarchical Temporal Memory
Common Cortical AlgorithmNeocortex
High-level properties of the neocortex
Hierarchical organization (spatial and temporal)
Using time as a supervisor
Ability to make predictions
Sparse Distributed Representations
Feed-forward and feedback connections
Sensory-motor
Kristian Valentın Hierarchical Temporal Memory
IntroductionNeocortex
Hierarchical Temporal Memory
Common Cortical AlgorithmNeocortex
Why unsupervised pre-training makes sense
If image-label pairs were generatedthis way, it would make sense to trygo straight from images to labels
If image-label pairs were generatedthis way, it makes sense to first learnrecover the stuff that caused theimage by inverting the highbandwidth highway.
Credit: G. Hinton
Kristian Valentın Hierarchical Temporal Memory
IntroductionNeocortex
Hierarchical Temporal Memory
Common Cortical AlgorithmNeocortex
Causes of the World
Kristian Valentın Hierarchical Temporal Memory
IntroductionNeocortex
Hierarchical Temporal Memory
HistoryMemory-Prediction Theory of Brain FunctionHierarchical Temporal MemoryGoals
Outline
1 IntroductionMotivationResearch GoalsTask of Visual Object Recognition
2 NeocortexCommon Cortical AlgorithmNeocortex
3 Hierarchical Temporal MemoryHistoryMemory-Prediction Theory of Brain FunctionHierarchical Temporal MemoryGoals
Kristian Valentın Hierarchical Temporal Memory
IntroductionNeocortex
Hierarchical Temporal Memory
HistoryMemory-Prediction Theory of Brain FunctionHierarchical Temporal MemoryGoals
History
1 Memory-Prediction Framework
proposed that the neocortex uses hierarchical sequence memory forstoring and inferring causes in the worldproposed several learning algorithms including a detailed mappingonto the large scale cortical-thalamic architecture, as well as ontothe microcircuits of cortical columns
2 Hierarchical Temporal Memory (HTM)
proper mathematical foundation for M-P frameworkmapping the mathematics of HTM directly to cortical-thalamicanatomy and the microcircuits of cortical columns
Kristian Valentın Hierarchical Temporal Memory
IntroductionNeocortex
Hierarchical Temporal Memory
HistoryMemory-Prediction Theory of Brain FunctionHierarchical Temporal MemoryGoals
History
1 Memory-Prediction Framework
proposed that the neocortex uses hierarchical sequence memory forstoring and inferring causes in the worldproposed several learning algorithms including a detailed mappingonto the large scale cortical-thalamic architecture, as well as ontothe microcircuits of cortical columns
2 Hierarchical Temporal Memory (HTM)
proper mathematical foundation for M-P frameworkmapping the mathematics of HTM directly to cortical-thalamicanatomy and the microcircuits of cortical columns
Kristian Valentın Hierarchical Temporal Memory
IntroductionNeocortex
Hierarchical Temporal Memory
HistoryMemory-Prediction Theory of Brain FunctionHierarchical Temporal MemoryGoals
Memory-Prediction Theory of Brain Function
Founded in On Intelligence (Hawkins Blakeslee, 2004)
Basic idea
The brain is a mechanism predicting the future and hierarchical regions ofthe brain predict their future input sequences.
Motivated by the observed fact that the mammalian neocortex isremarkably uniform in appearance and structure
Principally, the same hierarchical structures are used for a widerange of behaviors (+plasticity)
Assumptions
patterns from different senses are equivalent inside the brainthe same biological structures are used to process the sensory inputsa single principle (a feedback/recall loop) underlies processing of thepatterns
Kristian Valentın Hierarchical Temporal Memory
IntroductionNeocortex
Hierarchical Temporal Memory
HistoryMemory-Prediction Theory of Brain FunctionHierarchical Temporal MemoryGoals
Memory-Prediction Theory of Brain Function
Founded in On Intelligence (Hawkins Blakeslee, 2004)
Basic idea
The brain is a mechanism predicting the future and hierarchical regions ofthe brain predict their future input sequences.
Motivated by the observed fact that the mammalian neocortex isremarkably uniform in appearance and structure
Principally, the same hierarchical structures are used for a widerange of behaviors (+plasticity)
Assumptions
patterns from different senses are equivalent inside the brainthe same biological structures are used to process the sensory inputsa single principle (a feedback/recall loop) underlies processing of thepatterns
Kristian Valentın Hierarchical Temporal Memory
IntroductionNeocortex
Hierarchical Temporal Memory
HistoryMemory-Prediction Theory of Brain FunctionHierarchical Temporal MemoryGoals
Memory-Prediction Theory of Brain Function
Founded in On Intelligence (Hawkins Blakeslee, 2004)
Basic idea
The brain is a mechanism predicting the future and hierarchical regions ofthe brain predict their future input sequences.
Motivated by the observed fact that the mammalian neocortex isremarkably uniform in appearance and structure
Principally, the same hierarchical structures are used for a widerange of behaviors (+plasticity)
Assumptions
patterns from different senses are equivalent inside the brainthe same biological structures are used to process the sensory inputsa single principle (a feedback/recall loop) underlies processing of thepatterns
Kristian Valentın Hierarchical Temporal Memory
IntroductionNeocortex
Hierarchical Temporal Memory
HistoryMemory-Prediction Theory of Brain FunctionHierarchical Temporal MemoryGoals
Hierarchical Temporal Memory
Large-scale hierarchical model of the neocortex by Hawkins andGeorge, Numenta Inc. (2004, 2008)
Common cortical algorithm for all nodes
Learn common spatial patternsLearn common sequences of those patterns
Goal: Create a hierarchical, spatio-temporal model of data
Time is the teacher
Inference (recognition)
Bayesian belief propagationProbability of sequences passed upPredicted spatial patterns passed down
Kristian Valentın Hierarchical Temporal Memory
IntroductionNeocortex
Hierarchical Temporal Memory
HistoryMemory-Prediction Theory of Brain FunctionHierarchical Temporal MemoryGoals
Hierarchical Temporal Memory
Large-scale hierarchical model of the neocortex by Hawkins andGeorge, Numenta Inc. (2004, 2008)
Common cortical algorithm for all nodes
Learn common spatial patternsLearn common sequences of those patterns
Goal: Create a hierarchical, spatio-temporal model of data
Time is the teacher
Inference (recognition)
Bayesian belief propagationProbability of sequences passed upPredicted spatial patterns passed down
Kristian Valentın Hierarchical Temporal Memory
IntroductionNeocortex
Hierarchical Temporal Memory
HistoryMemory-Prediction Theory of Brain FunctionHierarchical Temporal MemoryGoals
Hierarchical Temporal Memory
Large-scale hierarchical model of the neocortex by Hawkins andGeorge, Numenta Inc. (2004, 2008)
Common cortical algorithm for all nodes
Learn common spatial patternsLearn common sequences of those patterns
Goal: Create a hierarchical, spatio-temporal model of data
Time is the teacher
Inference (recognition)
Bayesian belief propagationProbability of sequences passed upPredicted spatial patterns passed down
Kristian Valentın Hierarchical Temporal Memory
IntroductionNeocortex
Hierarchical Temporal Memory
HistoryMemory-Prediction Theory of Brain FunctionHierarchical Temporal MemoryGoals
Hierarchical Temporal Memory
Large-scale hierarchical model of the neocortex by Hawkins andGeorge, Numenta Inc. (2004, 2008)
Common cortical algorithm for all nodes
Learn common spatial patternsLearn common sequences of those patterns
Goal: Create a hierarchical, spatio-temporal model of data
Time is the teacher
Inference (recognition)
Bayesian belief propagationProbability of sequences passed upPredicted spatial patterns passed down
Kristian Valentın Hierarchical Temporal Memory
IntroductionNeocortex
Hierarchical Temporal Memory
HistoryMemory-Prediction Theory of Brain FunctionHierarchical Temporal MemoryGoals
Structure
Figure: (Maltoni, 2011)Kristian Valentın Hierarchical Temporal Memory
IntroductionNeocortex
Hierarchical Temporal Memory
HistoryMemory-Prediction Theory of Brain FunctionHierarchical Temporal MemoryGoals
Structure
Figure: (Maltoni, 2011)
Kristian Valentın Hierarchical Temporal Memory
IntroductionNeocortex
Hierarchical Temporal Memory
HistoryMemory-Prediction Theory of Brain FunctionHierarchical Temporal MemoryGoals
Structure of a Node
Kristian Valentın Hierarchical Temporal Memory
IntroductionNeocortex
Hierarchical Temporal Memory
HistoryMemory-Prediction Theory of Brain FunctionHierarchical Temporal MemoryGoals
Learning Algorithms
Spatial pooling
Learning common spatial patterns
Temporal pooling
Learning common sequences of those patterns
Kristian Valentın Hierarchical Temporal Memory
IntroductionNeocortex
Hierarchical Temporal Memory
HistoryMemory-Prediction Theory of Brain FunctionHierarchical Temporal MemoryGoals
Learning sequence
Kristian Valentın Hierarchical Temporal Memory
IntroductionNeocortex
Hierarchical Temporal Memory
HistoryMemory-Prediction Theory of Brain FunctionHierarchical Temporal MemoryGoals
Summary of Learning in the HTM Node
Kristian Valentın Hierarchical Temporal Memory
IntroductionNeocortex
Hierarchical Temporal Memory
HistoryMemory-Prediction Theory of Brain FunctionHierarchical Temporal MemoryGoals
Example of Resulting Representations
Figure: (Maltoni, 2011)
Kristian Valentın Hierarchical Temporal Memory
IntroductionNeocortex
Hierarchical Temporal Memory
HistoryMemory-Prediction Theory of Brain FunctionHierarchical Temporal MemoryGoals
Goals
strategy of generating training sequences
feedback information flow – covert attention (peripheral visual andmental focus)
complex natural imagesmulti-object recognition
experimenting with the training process
unsupervised pre-training followed be supervised refinement
studying sparse coding for increasing the scalability of HTM
incorporating color
Kristian Valentın Hierarchical Temporal Memory
IntroductionNeocortex
Hierarchical Temporal Memory
HistoryMemory-Prediction Theory of Brain FunctionHierarchical Temporal MemoryGoals
Goals
strategy of generating training sequences
feedback information flow – covert attention (peripheral visual andmental focus)
complex natural imagesmulti-object recognition
experimenting with the training process
unsupervised pre-training followed be supervised refinement
studying sparse coding for increasing the scalability of HTM
incorporating color
Kristian Valentın Hierarchical Temporal Memory
IntroductionNeocortex
Hierarchical Temporal Memory
HistoryMemory-Prediction Theory of Brain FunctionHierarchical Temporal MemoryGoals
Goals
strategy of generating training sequences
feedback information flow – covert attention (peripheral visual andmental focus)
complex natural imagesmulti-object recognition
experimenting with the training process
unsupervised pre-training followed be supervised refinement
studying sparse coding for increasing the scalability of HTM
incorporating color
Kristian Valentın Hierarchical Temporal Memory
IntroductionNeocortex
Hierarchical Temporal Memory
HistoryMemory-Prediction Theory of Brain FunctionHierarchical Temporal MemoryGoals
Goals
strategy of generating training sequences
feedback information flow – covert attention (peripheral visual andmental focus)
complex natural imagesmulti-object recognition
experimenting with the training process
unsupervised pre-training followed be supervised refinement
studying sparse coding for increasing the scalability of HTM
incorporating color
Kristian Valentın Hierarchical Temporal Memory
IntroductionNeocortex
Hierarchical Temporal Memory
HistoryMemory-Prediction Theory of Brain FunctionHierarchical Temporal MemoryGoals
Goals
strategy of generating training sequences
feedback information flow – covert attention (peripheral visual andmental focus)
complex natural imagesmulti-object recognition
experimenting with the training process
unsupervised pre-training followed be supervised refinement
studying sparse coding for increasing the scalability of HTM
incorporating color
Kristian Valentın Hierarchical Temporal Memory
IntroductionNeocortex
Hierarchical Temporal Memory
HistoryMemory-Prediction Theory of Brain FunctionHierarchical Temporal MemoryGoals
Article
Stolc, Bajla, Valentın, Skoviera: Pair-Wise Temporal PoolingMethod for Rapid Training of the HTM Networks, Vol. 31, 2012,901–919
64 pixels
Rectangles Triangles Circles
8 pixels
Kristian Valentın Hierarchical Temporal Memory
IntroductionNeocortex
Hierarchical Temporal Memory
HistoryMemory-Prediction Theory of Brain FunctionHierarchical Temporal MemoryGoals
Codebook Generation
Proposed coordinates Accepted coordinates Codebook
Kristian Valentın Hierarchical Temporal Memory
IntroductionNeocortex
Hierarchical Temporal Memory
HistoryMemory-Prediction Theory of Brain FunctionHierarchical Temporal MemoryGoals
Pair-wise Explorer
Smooth explorer Pair-wise explorer
...
Kristian Valentın Hierarchical Temporal Memory
IntroductionNeocortex
Hierarchical Temporal Memory
HistoryMemory-Prediction Theory of Brain FunctionHierarchical Temporal MemoryGoals
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Kristian Valentın Hierarchical Temporal Memory
IntroductionNeocortex
Hierarchical Temporal Memory
HistoryMemory-Prediction Theory of Brain FunctionHierarchical Temporal MemoryGoals
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Kristian Valentın Hierarchical Temporal Memory
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