Cortical spreading depression (CSD) evokes substantial changes in blood oxygen level-dependent (BOLD) functional magnetic resonance imaging (fMRI) and spin-lock (SL) signals in the rat brain cortex. (A) Typical activation patterns during propagation of CSD as characterized by BOLD fMRI. The SL activation maps have a power (B1,SL) of (B) 500 Hz and (C) 6,000 Hz. Signal increases (warm colors) and decreases (cold colors) indicate t values. The maps are superimposed on the high-resolution anatomic reference image. (D) Relative BOLD fMRI (blue), SL-w500Hz (green), and SL-w6000Hz (red) time courses averaged across five subjects (mean±s.d.). The inset image shows a typical region of interest (yellow). (E) Relative SL500Hz (dark yellow) and SL6000Hz (dark red) responses compared with BOLD fMRI response (blue). (F) Peak signal change averaged across five subjects (±s.d., *P<0.05, **P<0.001, paired t-test).