Figure 1.

Example of one simultaneous measurement of blood oxygen level-dependent (BOLD) signals and electrophysiological responses in the rat dentate gyrus during electrical stimulation of the right perforant pathway. (A) The perforant pathway was electrically stimulated with three consecutive stimulation blocks, each containing seven identical stimulation trains. The duration of one stimulus train was 8 seconds, followed by 52 seconds rest. The stimulus frequency was always doubled in the subsequent train and, if not otherwise mentioned, three different frequencies (here 0.625, 1.25, and 2.5 Hz) were applied during one experiment. (B) Time course of BOLD signal intensities in the right dentate gyrus during the entire experiment. The time course represents the variations in BOLD signal intensities of all significantly activated voxels in this region. The gray bars indicate the stimulation periods (i.e., 8 seconds trains). (C) Time course of field potentials during the entire stimulation period (8 seconds, equivalent to the gray bars in B). The arrows indicate the first two elicited population spikes. (D) For each recorded population spike, the amplitude and latency was determined. The location of the stimulus artifact is indicated with dashed arrow. (E) For comparison all elicited population spike within one train are overlaid, the first population spike is highlighted in red. The color reproduction of this figure is available on the Journal of Cerebral Blood Flow and Metabolism journal online.