Source
Donoghue, Schaworonkow and Voytek (2021), LIT-1999, pp. 9–19 and 39 of the PsyArXiv preprint; read in NOTE-1529.
What was actually shown
Aperiodic activity, 1/f^χ with χ “often” between 0 and 4, is “a ubiquitous and sometimes dominant feature of neural field data”, linked to postsynaptic potentials (p. 9). Because it has power at every frequency, “any spectral measure … will always return a numerical value for power for a given frequency band, even if there is no oscillatory activity present” (p. 9). In simulation, a change in χ alone yields a difference in alpha power (Fig. 3B), a pattern of changes across five bands (Fig. 3C–D) and a change in relative alpha power (Fig. 3E). Empirically, the reported link between ADHD and the theta/beta ratio “appears to be driven by aperiodic activity” (p. 18, Robertson et al. 2019). The exponent varies with age, diagnosis, sleep and task (p. 17).
What this does not say
- That 1/f activity is meaningless. It is “itself a physiologically informative feature … reflecting processes distinct from neural oscillations” (p. 39).
- That it is or is not a signature of a macro-level constraint. The paper does not address emergence. What follows from it for THEORY-1314 is narrower: since every field recording shows 1/f structure, its presence does not discriminate between accounts.