Hey, I'm Marcus.

I study machine learning and the brain.

Current research

The computational principles of the brain have been partially illuminated by studying how it keeps track of physical space. When a mammal performs a spatial task, large portions of the brain are devoted to tracking spatial variables like locations and orientations, and they do so in ways that are surprisingly simple and clever. When performing a non-spatial task, those same neurons again devote themselves to tracking relevant details, but in ways that are less understood. This raises a natural question: what is the "base algorithm" here? Is this neural circuitry essentially a space processor, handling many different scenarios by treating them as spatial tasks? Or, at its core, is it some other type of processor that is naturally capable of handling physical space? By exploring the set of possible neural algorithms that fit the past few decades' experimental results, we may gain insight into how today's AI can be improved. And by evaluating how these possible neural algorithms can be used by today's AI, we may gain insight into how the brain makes sense of the world.

This is my main project at Numenta. (Fun fact: We live-stream most of our research meetings.)


Hippocampal Spatial Mapping As Fast Graph Learning
Marcus Lewis
Poster at 30th Annual Computational Neuroscience Meeting (2021)
Efficient and flexible representation of higher-dimensional cognitive variables with grid cells
Mirko Klukas, Marcus Lewis, Ila Fiete
PLOS Computational Biology (2020)
A Framework for Intelligence and Cortical Function Based on Grid Cells in the Neocortex
Jeff Hawkins, Marcus Lewis, Mirko Klukas, Scott Purdy, Subutai Ahmad
Front. Neural Circuits (2019)
Locations in the Neocortex: A Theory of Sensorimotor Object Recognition Using Cortical Grid Cells
Marcus Lewis, Scott Purdy, Subutai Ahmad, Jeff Hawkins
Front. Neural Circuits (2019)

Other projects, big and small

Using Grid Cells for Coordinate Transforms
Marcus Lewis
Poster, Grid Cell Meeting 2018, UCL, London, England
Grid cells: Visualizing the CAN model
A weekend in April 2017
See HTM run: Stacks of time series
Written while living in hostels. February 2016
A visual running environment for HTM
Collaboration with Felix Andrews. November 2015


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