Fig 1.
a) Cb is divided into three main parts—vermis (medial Cb; will be denoted in the text with a “v”), paravermal (medio-lateral Cb) and hemispheres (lateral Cb; both of which will be denoted collectively in the text with an “h”)–which are then further divided into ten numbered lobules, arranged dorsoventrally I-X. Task-related activations were expected in five regions of interest: oculomotor vermis (vVI-VII) & hVIIb for the PA task, with possible cognition-related activation in lobules CrusI & CrusII (hVII), and in hV & hVIII for the FT task. These lobules are color-coded and overlaid on an average Cb from the SUIT toolbox [20] and listed, in matching colors, on the right. b) top–Two high-density surface coils with 16 elements each were used for signal reception (adapted from [21]), bottom–the coils were placed beneath Cb using the inion of the skull as a landmark and accurate placement was confirmed with a scout scan. c) The stimulus sequence was identical for both eye- and finger-movement tasks: In the pro-/anti-saccade (PA) task subjects made eye movements to locations which were either identical to (pro-saccade) or opposite from (anti-saccade) the location of a white target that appeared after a red or a blue central cue; color and movement direction pairings were counterbalanced across subjects. In the finger tapping (FT) task subjects moved their thumb at 2 Hz whenever the dots were moving. In each task the active period lasted for 20s and alternated with 20s of fixation for one full run of eight minutes.
Fig 2.
Functional Accuracy of Pro-Anti Activations in Cb, Oculomotor Vermis and Paravermis VI.
Activity in OMV (medial posterior Cb, layers vVIc and vVII, central panel) and paravermis VI and CrusII/VIIa during the PA task is displayed on sagittal slices (vertical lines dissecting rightmost coronal view). Ventral OMV is active in all subjects besides S05 during this task while activity is also present in dorsal OMV for all subjects besides S03 and S04; slices are through Cb vermis and paravermis only. Slice locations (sagittal non-normalized MNI space, x-plane) are displayed at the top of each panel. Refer to Fig 1a for a guide to anatomical lobule definitions.
Fig 3.
Functional Accuracy of Pro-Anti Activations in Cb, Bilateral VI.
Bilateral hVI is activated during PA; crosshairs denote an active cluster in left paravermis VI and distinct clusters can be seen aligned along lobule VI in the axial (rightmost) panels. Slice locations (in non-normalized MNI space) are displayed at the top of each panel and T-values at the crosshairs are displayed at the bottom of the axial panels. Refer to Fig 1a for a guide to anatomical lobule definitions.
Fig 4.
Functional Accuracy of Thumb Tapping Activations in Cb, Ipsilateral IV-VI.
Ipsilateral hIV-VI is activated during the FT task; crosshairs denote an active cluster in or adjacent to right hV (S04 –hVI-VII). Activations for both tasks are shown in all images, with PA activity denoted by red-yellow and FT activity by blue-green color bars. Note the large structural and functional (with regard to both location and strength) variability between subjects; maximum FT-clusters can be located anywhere between the IV-V border (S03, S05 and S06) to the V-VI border (S01, S02, S04). Slice locations (in non-normalized MNI space) are displayed at the top of each panel and T-values at the crosshairs are displayed at the bottom of the axial (rightmost) panels. Refer to Fig 1a for a guide to anatomical lobule definitions.
Fig 5.
Functional Delineation of Task-Related Activity, Pro-Anti Activations in CrusI and CrusII.
PA-related activity is also seen in hCrusI and/or hCrusII (crosshairs); presumably due to the cognitive component required to plan and execute a volitional anti-saccades. Clusters occur in either dorsal CrusI (S01, S03 and S06) or medioventral CrusII (S02, S04 and S05). Slice locations (in non-normalized MNI space) are displayed at the top of each panel and T-values at the crosshairs are displayed at the bottom of the axial (rightmost) panels. Refer to Fig 1a for a guide to anatomical lobule definitions.
Fig 6.
Functional Delineation of Task-Related Activity, Separation of Eye and Finger Movements in Ventrolateral Cb.
Example of the specificity of localized activity resulting from the two motor systems (in addition to the obvious distinctions visible in Figs 2–5): differentiation of FT-related hVIII activity from PA-related hVIIb activity is displayed for each subject (zoomed-in area denoted by a dotted box); activations from separate tasks do not overlap. Separable activations are located more anteriorly in some subjects (S02, S05 and S06, axial slices) and the proximity and arrangement of the clusters also varies between subjects. Slice locations (in non-normalized MNI space) are displayed at the top of each panel and maximum T-values from within the zoomed areas are displayed at the bottom of the axial (rightmost) panels, color-coded by task—PA in red-orange and FT in blue-green. Refer to Fig 1a for a guide to anatomical lobule definitions.
Fig 7.
Concomitant Correlation of Task-Related Cb Cortex Activity and Anticorrelation of DCN Activity.
The detail of the T2W scan allows visualization of DCN revealing increases (+) and decreases (-) in task-related functional activity in Cb cortex and within the dentate (respectively) of a single subject. Correlation of task-related activity (+) in the Cb cortex is concomitant with anticorrelation of activity (-) in the dentate and that cognitive depression (PA, green at -57) is located more caudal in the dentate than (the stronger) motor depression (FT, purple at -48). Slice locations (in non-normalized MNI space) are displayed at the top of each panel and maximum T-values from clusters within the circles are displayed at the bottom of the panels; coloring matching the respective color bar. Refer to Fig 1a for a guide to anatomical lobule definitions. FN—fastigial nucleus, IN—interpositus nucleus, D—dentate nucleus.
Table 1.
Oculomotor Vermis Coordinates and Maximum T Values.
Fig 8.
Inter-Subject Variability of Normalized Cb Activations.
a) left—Normalized PA-activity, crosshairs at left paravermis VI; right—normalized FT-activity, crosshairs at ipsilateral (right) V; data are from all subjects, each subject is color-coded. b) PA activity is localized to oculomotor vermis (VIc and VII), bilateral hVI, and (right) hCrusI/II for all subjects. c) FT-activity in ipsilateral hV/VI for all subjects and ventral activity only for S01, S02 and S05. Activations from both tasks are clustered within the expected lobules yet inter-subject activations rarely overlap. Activations are T-maps from SUIT normalized functional images with Cb mask overlaid on SUIT template Cb [20]. Each subject is represented by a single color cluster-thresholded at p < .05 (AT).