Figure 1.
Combined structural brain imaging, functional brain imaging, and SSEP recording after focal ischemic stroke. T2 maps (first column), BOLD spin-echo echo-planar images (SE-EPI) during right (second column) and left (third column) forepaw stimulation, and the corresponding SSEP signals from S1FL (fourth column; left hemispheric SSEP signal in blue; right hemispheric SSEP signal in red) from representative animals with no loss (group 1), transient loss (group 2), and permanent loss (group 3) of BOLD activation in the right primary somatosensory cortex. BOLD activation and normal SSEP signals can be observed in both primary somatosensory cortices in all animals during baseline measurements (B), i.e., before transient MCAO. No loss of BOLD activation and normal SSEP signals are found in animals with subcortical infarction (group 1) at all time points during the 7 week observation period. In animals with a transient loss of BOLD activation in the right S1FL area (group 2), the right SSEP signal is delayed and diminished 2 d after MCAO (D2) and delayed 1 week after MCAO (W1). In parallel with reemergence of BOLD activation 2 weeks after MCAO (W2), a normal SSEP signal is observed again. In animals with permanent loss of BOLD activation in the right S1FL area (group 3), no restoration of the SSEP signal is observed over time. Note that the first spike at time point 0 represents the electrical stimulus in the SSEP recording.