Surprisingly Complex Waves Reveal the Brain’s Inner Workings

gist

Conor Feehly reports for Quanta Magazine that intracranial recordings show traveling brain waves with sources, sinks, and spiral forms tied to memory tasks. Researchers including Joshua Jacobs argue these patterns may reorganize cortex on behavioral timescales. György Buzsáki counters that extracellular waves mainly reflect synaptic activity underneath.

ideas

• Traveling waves look more structured than planar noise. Jacobs, Anup Das, and collaborators measured concentric source and sink waves plus rotating spirals in people with intracranial electrodes, and linked different patterns to verbal versus spatial memory tasks.
• Direction may track encoding versus recall. Earlier work with Uma Mohan described front-to-back and back-to-front cortical waves that track information moving between visual areas and prefrontal memory regions.
• Spirals may suit harder memory work. Jacobs reports rotating waves more often during spatial navigation recall than during simpler verbal recall, and Bard Ermentrout suggests older planar readings may have been outer arms of unseen spirals.
• Mice show mirrored rotating waves with spiral wiring. Zhiwen Ye and Nicholas Steinmetz found synchronized circular waves across hemispheres and axonal loops in somatosensory cortex that may support them.
• Not everyone treats the field as causal. Buzsáki says the extracellular pattern follows synaptic current and action potentials, so it informs circuitry without needing an independent computational role in the field itself.

quotes