Hierarchical Temporal Memory (HTM)

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Hierarchical Temporal Memory (HTM) Computational Cognitive Neuroscience COSC 521, Spring 2019 Corey Johnson Resources for information on HTM Numenta.org HTM school NuPIC Jeff Hawkins 2004 book: On Intelligence: How a New Understanding of the Brain will Lead to the Creation of Truly Intelligent Machines (Note: some slide graphics are from Numenta.org, HTM school) 2 Hierarchical ● Higher levels → abstraction & permanence Temporal ● Change over time: patterns Memory ● Sparse Distributed Representation (SDR) 3 HTMs ● Biologically plausible model for intelligence ● Based on pyramidal neurons ● Neocortex micro-columns as building blocks "The neocortex comprises about 75% of the volume of the human brain and it is the seat of most of what we think of as intelligence." -Jeff Hawkins 4 HTMs continued ● Can learn / recall / infer high-order sequences ● Local learning rules, no global supervisor (HW) ● Relies on sparse distributed representation (SDR) ○ Fault tolerance ○ High capacity ● Learns by modeling the growth of new synapses 5 ANN Pyramidal HTM 6 HTM Layers (Lect. 2 slides) 7 Sparse Distributed Representation Fundamental to HTM systems SDR: 'Language of intelligence' Sparse as opposed to dense binary code, many bits are needed SDR bit similarity → similar semantic meaning Semantic error is key to generalization Cell only needs a few connections to neighbor to match pattern 8 Applications Good for: ● Data streams that change over time: text, GPS, dates, numbers ● Data with inherent structure ● System where many models are required rather than one large one ● Prediction ● Anomaly detection ● Classification 9 HTM theory is still evolving 10 11 HTM School videos 12 13 14 Video Link: https://youtu.be/v-VvFRar5TY 15 Video Link: https://youtu.be/X50GY0mdHlw 16 Video Link: https://youtu.be/Nqoruj4eCb8 17 Stocks Geospatial Rogue Behavior 18 Conclusion HTM aims to be a biologically-constrained theory of intelligence You may hear more about HTMs in the future Needs killer app moment like DCNN (ImageNet) or DRL (Go/Chess) Resources: ● Numenta.org ● HTM School ● NuPIC code ● HTM Studio 19 Questions / Comments / Thoughts? Thanks! (For more information on HTMs, please see Numenta.org) 20.

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