A Functional and Structural Investigation of the Human Fronto-Basal Volitional Saccade Network
Figure 5
The average peri-stimulus-time-histograms (PSTHs; BOLD time courses) are shown for several ROIs: the clusters activated for saccades in darkness vs rest in left and right precentral sulcus/premotor cortex (‘lateral and medial FEF’) and the left and right putamen and SEF, and the left and right clusters in the FEF more active for anti as compared to prosaccades (‘antisaccade FEF’). The aforementioned group activation patterns from which the ROIs were taken are depicted in figure 4. PSTHs were averaged over voxels in the ROIs and then participants, and aligned at target stimulus onset. Saccade onset typically follows within 300 ms, therefore PSTHs aligned at saccade onset would have been largely identical. Data for the left hemisphere are given in the left panels and data for the right hemisphere in the right panels. In each panel, average PSTHs are presented for pro and antisaccades (gray squares and black circles) to the left and right (solid and dashed lines with open and solid symbols). The unit on the ordinate is global % signal change. The absolute magnitude of this unit is not directly meaningful and should not be compared over regions, as averaging took place over different numbers of voxel per region and within different brain areas. Absolute BOLD measures are known to vary considerably over regions. Differences between conditions within a region can be compared. Except the bilateral putamen, the right ‘lateral FEF’ and left SEF, peak activation in all ROIs was significantly larger for antisaccades as compared to prosaccades (p<0.05). The left SEF exhibited larger responses for antisaccades at trend level, T(12) = 1.59;p = 0.06. Further tests on single timepoints of interest are presented in the text of the results section.
