Spatial specificity of post-stimulus BOLD undershoot signal
Wang P, Jin T, Kim S, Zhao F
Spatial specificity of the post-stimulus BOLD undershoot signal has been tested by high-resolution fMRI in response to visual stimulus of isoflurane-anesthetized cats at 9.4T using GE techniques. BOLD and CBV-weighted data were acquired without and with injection of MION, respectively. The positive BOLD signal was spread across the cortical layers, while both post-stimulus BOLD undershoot and CBV-weighted fMRI signals peaked at the middle cortical layer. Additional BOLD study was performed to investigate TE dependence of post-stimulus BOLD signal. The post-stimulus BOLD undershoot is TE-dependent and is ikely caused by the elevated oxygen consumption.