How many labels can a biological oscillator carry? A quality-factor screen for proposed information carriers
How many messages can a brain rhythm actually carry at once?
A new physics-based test shows that biological oscillators can carry only as many distinct labels as their quality factor allows—a limit set by how sharply tuned the oscillation is to a single frequency. When applied to proposed high-frequency brain signals, most candidates fail this test spectacularly: a recently proposed 30 GHz field in the cortex has a quality factor of just 0.19, meaning its signal spreads five times wider than the frequency it's supposed to carry, making distinct labels impossible to distinguish.
Neuroscientists have proposed multiple mechanisms for how the brain might encode information in oscillating signals—from electromagnetic fields to quantum effects in microtubules. This test provides a single, mechanism-independent standard to rule out implausible candidates before investing time and resources studying them. It eliminates most high-frequency proposals immediately, while showing that only the brain's low-frequency rhythms have the spectral sharpness needed to reliably carry multiple distinct signals.