A Functional and Structural Investigation of the Human Fronto-Basal Volitional Saccade Network (original) (raw)
Figure 7
Step-wise results of DTI analysis.
The subsequent steps in DTI fiber analysis are outlined in 4 panels. In panel A, the normalized fiber tracts originating from the left and right putamen and caudate nucleus are rendered in blue for one participant together with orthogonal slices from the normalized T1 weighted scan. The manually segmented ROIs for the caudate nucleus and putamen are also rendered in red. Panel B shows a 3D representation of the average probability (over participants) for a voxel to be connected to the caudate nucleus (in red) or putamen (in blue) or both (purple). In yellow the zones activated for antisaccades and in green the zone activated for saccades in darkness are rendered. For each participant, it was then investigated which fibers from the 4 fiber bundles originating in the left and right putamen and caudate nucleus were connected to the most important cortical fMRI activation clusters observed in 4. See panel C for example results from individual participants: fibers connecting the caudate nucleus and SEF are shown in the left rendering, fibers connecting the putamen and antisaccade zone in the FEF in the right rendering, and the lower left rendering shows fibers connecting the areas activated for saccades in darkness (‘lateral and medial FEF’) with the putamen. The manually segmented caudate nucleus and putamen are also shown in yellow and green, respectively. Panels C is presented in order to illustrate the fiber processing steps, and are not necessarily representative. Panel D shows for how many participants (out of 12) regions were connected at all. ‘FEF motor’ refers to zones along the precentral sulcus activated for saccades in darkness (that is, ‘lateral FEF’ and ‘medial FEF’ taken together), ‘FEF anti’ refers to zones activated for antisaccades vs prosaccades. Line thickness also indicates the number of subjects with connections. The diagram is overlayed onto a blurred slice from figure 4, only to roughly indicate the location.