Fig 5. 1/f-like fluctuations persist when neural activity is suppressed.

(A) Experimental setup. (B) Example traces showing PtO₂ responses to locomotion at sites 170 μm below brain surface before (left) and after (right) application of CNQX/AP5/muscimol in the well over the craniotomy. Top, black tick marks denote locomotion events; middle, PtO₂ (black) and respiratory rate (orange) responses to locomotion; bottom, example of data showing spectrogram of LFP (cyan trace showing the gamma-band power). (C) Comparison of resting gamma-band power of LFP and PtO₂ fluctuations quantified with the SD of the signal. Black circles and bars outside the axes show the population mean and SD. The dashed gray line is the unity line. Clustering of the points in the upper left corner shows a pronounced decrease in the neural activity was not accompanied by a decrease in the amplitude of the oxygen fluctuations. (D) Power spectrum of tissue oxygen signal before (black) and after (red) application of CNQX/AP5/muscimol using resting data (left) and data including both rest and locomotion (right). The dashed line indicates the linear regression fit. Data are shown as mean ± SEM. (E) Power law exponent of tissue oxygen signal before (black) and after (red) application of CNQX/AP5/muscimol using resting data (left) and data including both rest and locomotion (right). *paired t test, t(8) = 4.4711, p = 0.0021 (rest, n = 9 mice); t(8) = 2.5967, p = 0.0318 (rest and locomotion, n = 9 mice). (F) As (E) but for DFA scaling exponents. *paired t test, t(8) = 5.0287, p = 0.0010 (rest, n = 9 mice); t(8) = 2.9959, p = 0.0172 (rest and locomotion, n = 9 mice). Data in (E) and (F) are shown as median ± interquartile range using boxplot, with the sample mean shown as dashed lines. The data used to generate this figure are available at https://doi.org/10.5061/dryad.pg4f4qrmt. aCSF, artificial cerebrospinal fluid; fluid; AP5, (2R)-amino-5-phosphonopentanoic acid; CNQX, 6-cyano-7-nitroquinoxaline-2,3-dione; DFA, detrended fluctuation analysis; FC, frontal cortex; FL/HL, forelimb/hindlimb; LFP, local field potential; SD, standard deviation.