Stimulus Frequency Dependence of the Relationship between BOLD Signal and Somatosensory Evoked Potential in Rat Cortex
Kida I, Tamura M, Yamamoto T
Since the BOLD signals correlate with hemodynamic changes such as deoxygenated hemoglobin and CBF, the stimulus frequency dependence should match both for BOLD signal, deoxygenated hemoglobin and/or CBF. However, an fMRI study using the gradient-echo BOLD signal reports a conflicting result with CBF measurement and optical imaging for the stimulus-frequency dependence in rat forepaw stimulation model. We investigated whether the BOLD signal correlates with hemodynamic changes and neuronal events for the various stimulus frequencies. Result that the spin-echo BOLD signal peaked at 3-5Hz stimulus frequency paralleled with the changes in hemodynamics and the integrated somatosensory evoked potential amplitude.