Numenta Research Meeting - Feb 12, 2020

Not sure what Jeff will talk about yet, but he seems excited about something.


Is this actually supposed to happen 50 minutes ago or is there something wrong?
YouTube says so.

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Fixed, thanks.


Cortical Travelling Waves: Mechanisms and Computational Principles; Terry Sejnowski, Salk Institute

The whole talk is here:

A very nice open-source paper on these Metastable brain waves


Traveling patterns of neuronal activity—brain waves—have been observed across a breadth of neuronal recordings, states of awareness, and species, but their emergence in the human brain lacks a firm understanding. Here we analyze the complex nonlinear dynamics that emerge from modeling large-scale spontaneous neural activity on a whole-brain network derived from human tractography. We find a rich array of three-dimensional wave patterns, including traveling waves, spiral waves, sources, and sinks. These patterns are metastable, such that multiple spatiotemporal wave patterns are visited in sequence. Transitions between states correspond to reconfigurations of underlying phase flows, characterized by nonlinear instabilities. These metastable dynamics accord with empirical data from multiple imaging modalities, including electrical waves in cortical tissue, sequential spatiotemporal patterns in resting-state MEG data, and large-scale waves in human electrocorticography. By moving the study of functional networks from a spatially static to an inherently dynamic (wave-like) frame, our work unifies apparently diverse phenomena across functional neuroimaging modalities and makes specific predictions for further experimentation.
Do check out the movies in the supplemental material section:

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Commenting on discussion around 15:20, it seems to me that the base frequency increasing as the critter moves faster is necessary if these are resulting in grid cells. The bumps of activity triggered by the interference pattern need to correspond to consistent physical locations regardless of how fast the critter were running. If the base frequency didn’t increase as the critter’s speed increased, then the grid cell bumps would spread out further apart as if the room were expanding in size.

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