Taking ‘brain waves’ seriously: Neuroacoustics

June 14, 2017

Our research collective has been doing a lot of work touching on brain dynamics, resonance, and symmetry: see here and here (video). Increasingly, a new implicit working ontology I’m calling ‘Neuroacoustics’ is taking shape. This is a quick outline of that new ontology.

What is Neuroacoustics?

A common frame in neuroscience is to talk about ‘brain waves’; alpha waves, gamma waves, and so on. Neuroacoustics essentially doubles down on this wave metaphor, but instead of focusing on specific wave frequencies, it focuses on their relative frequencies and the properties of the substrates in which these waves travel. In short, I propose that neural activity can be understood as waves in an adaptive medium, and adaptive behavior as arising from the interplay between the information encoded in the waves and the information encoded in the resonant and topological properties of the medium. Wave dynamics would arise from (e.g.):

(1) Inherent acoustics of the substrate. I.e., different brain regions propagate waves & resonate differently based on local connectivity, myelination, & gene expression.

(2) Topological permutations of multiple resonant substrates. Trumpets produce beautiful order by connecting many resonant chambers together in a way which leads to signal selection, purification, and amplification. The brain’s internal topology is likely organized around similar principles, just in a more complex, layered way that imparts semantic context.

(3) Adaptive interactions between wave & substrate. My intuition is that we could model short-term and long-term potentiation in terms of wave resonance wearing ‘grooves’ (wave guides) into the substrate. Contrawise, perhaps some substrates are primed for the opposite effect: patterns which are too resonant trigger the brain’s defense against monopolization of neural resources (“boredom”).

(4) Interaction between waves – i.e., constructive & destructive interference, especially when periodicities overlap or near-overlap.

(5) Neurotransmitters influencing acoustics. We can model neurotransmitters as ‘resonance-shifters’ which operate on a per-region basis to change their internal (Darwinian) pattern selection landscapes. Emotions, then, can be thought of as coordinated bundles of these resonance-shifters, with each bundle calibrated for different environmental challenges.

(6) Interactions with other periodic systems & patterns. Our brains are very good at getting ‘in synch with’ all manner of other systems (entrainment), especially other brains.

Truust Neuroimaging uses (1) and (2) to build 3d reconstructions of activity from EEG data; Selen Atasoy uses (1), (2), (5), and (6) to model the effects of LSD and music on brain harmonics; my colleague Andres recently gave a talk proposing how to use (1), (2), (4), (5), and (6) to build an objective measure for valence in humans. And we aren’t done yet- there’s a lot of cool stuff this framework makes easier, just waiting to be built.

Speculation: the Periodic Table of Brain Regions

We can approach the description above as a working metaphor and call it done, but there may also be room for something more formal. Specifically, Neuroacoustics seems to imply we could build a principled parametrization of neural substrate based on conditional resonance. In practice this would entail measuring various brain regions’ stochastic resonant properties, then classifying the effects of various neurotransmitters (serotonin, dopamine, opioids, etc) on these resonant properties, and organizing the result by periodic structure. I call this the “Periodic Table of Brain Regions”.

If this parametrization pans out, it could help comprehensively parametrize all mind-altering effects of all psychoactive substances, from Benadryl to chocolate to nicotine, and also clear a path for the next step: targeted, precision interventions.

See also: Atasoy’s work on Connectome Harmonics and Emilsson’s extension to valence; Adaptive Resonance Theory; Steve Lehar‘s work; Smolensky’s Computational Harmony; a broad range of work on neural entrainment.

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