TUS-evoked time–frequency cross-coupling of low-frequency calcium oscillations and BOM. (a) Frequency-dependent wavelet ridges with time as the main axis (solid white line) in the time–frequency diagram of neuronal calcium oscillations and BOM. (b)–(e) The average spectrum distribution of neuronal calcium oscillation, HbO, HbR, and HbT, (b) neuronal calcium oscillation, (c) HbO, (d) HbR (e) HbT. (f)–(h) The relative changes of FWR(ΔFWR/FWR) between HbO, HbR, HbT and neuronal calcium oscillation at different time bands, (e) Ca²⁺ vs. HbO, (f) Ca²⁺ vs. HbR, (g) Ca²⁺ vs. HbT (mean ± SEM, n = 9 for each group, ^*P < 0.05, ^**P < 0.01, ^***P < 0.001; paired t-test).