Article Figures & Data
Figures
- Figure 1.
The arrangement of relevant areas in the macaque frontal lobe. 3-D reconstruction of the magnetic resonance image of a macaque monkey brain (A) and a schematic drawing of the frontal region (B); the three eye movement-related areas are in shades of red: the FEF, SEF, and PMVe (Bruce et al., 1985; Bruce and Goldberg, 1985; Fujii et al., 1998). In shaded area posterior to the arcuate sulcus outlines, the areas where lesions impair monkey performance on conditional motor selection tasks (CM), i.e., anterior area 6 in the posterior bank of the arcuate sulcus (Halsband and Passingham, 1982; Petrides, 1987) and the area lesions of which impair the conditional selection of visual stimuli (CVS), i.e., area 8A (Petrides, 1987). A, BII, Section through the arcuate sulcus to show the locus of the microstimulation elicited eye movements, i.e., the FEF (Bruce et al., 1985; Bruce and Goldberg, 1985). This region lies immediately posterior to granular area 8A (Stanton et al., 1989; Tehovnik et al., 2000; Gerbella et al., 2007). C, Area 8A can be divided, based on the characteristic corticocortical connectivity pattern, into a ventral (i.e., area 8Av) and a dorsal part (i.e., area 8Ad). The ventral part of area 8Av is connected to higher-order visual occipital and temporal areas (Petrides and Pandya, 1988, 1999, 2006). D, Corticocortical connectivity pattern of area 8Av showing cortical terminations and association fiber pathways (adapted from Petrides and Pandya, 2006). AS: arcuate sulcus; CM: conditional motor selection; CS: central sulcus; CVS: conditional visual selection; ExtmC: extreme capsule; FEF: frontal eye field; FOF: fronto-occipital fasciculus; ILF: inferior longitudinal fasciculus; IPS: intra-parietal sulcus; PMVe: ventral premotor eye area; PS: principal sulcus; SEF: supplementary eye field; SPdimple: superior precentral dimple; SLF II: superior longitudinal fasciculus II; STS: superior temporal sulcus.
- Figure 2.
Timeline illustrating the various trials of the fMRI experiment. On the top are the four conditional trials. Subjects had learned (before scanning) which one of the black circles had to be selected based on the color of the central circle and moved their eyes to look at the appropriate black circle. In the control condition, the central color was always beige and one of the circles was black and the others gray and the subjects moved their eyes to the one black circle. The location of the black circle (as opposed to the gray ones) was determined according to a random order with all four locations appearing in black with the same frequency over one complete run. On each particular trial, control or conditional, subjects were presented with a colored circle in the center and four marked locations surrounding it and had to move their eyes to one particular location. Thus, in the control condition, the exact same looking and eye movement response was required, as in the conditional task, but the response was determined by the shading of the dot, and, therefore, the subject did not have to make a selection between alternative looking responses based on conditional rules.
- Figure 4.
The BOLD level hemodynamic response curves reconstructed in all subjects for the four relevant peaks in each hemisphere (only peak voxel for each subject/contrast; using all trials over the 3 runs). The mean curves are plotted with standard error as shaded area for the right (A) and left (B) hemispheres. The peaks are: CVS/8Av (I); PMVe/iPCS (II); FEF/sPCS (III); SEF (IV). Zero second is event onset (presentation of the stimulus that initiates the eye-movement to a particular location). The conditional visual selection peak (CVS) in area 8Av shows changes in BOLD response only in the conditional selection condition in which the target is selected on the basis of an internal cognitive decision according to a known rule. It is important to note that this area -as opposed to all eye-movement areas- is not involved in moving the eyes per se (compare stimulus-driven eye movement (green) vs eye movement based on conditional rule (blue) in AI and BI). Also note that the effects are found across all subjects. CVS/8Av: Conditional Visual Selection in area 8Av in the posterior middle frontal gyrus; iPCS: inferior Precentral Sulcus eye area; PMVe: Premotor Eye-area; FEF: Frontal Eye Field area; SEF: Supplementary Eye Field area; sPCS: superior Precentral Sulcus eye area.
- Figure 3.
The location of the activation peaks demonstrated in the functional experiment: the conditional visual selection in area 8Av (CVS/8Av), the FEF in the superior PCS (FEF/sPCS-superior PCS eye area), the SEF on the medial frontal region and the PMVe (PMVe/iPCS-inferior PCS eye area). The peaks associated with eye movement (i.e., eye movement condition MINUS fixation) are shown in hot colors. The peak associated with the conditional eye movement looking responses MINUS control location-induced eye movement is in spectral color. A, Right hemisphere. B, Left hemisphere. I, SEF and FEF in a coronal section. II, CVS in area 8A and the PMVe in a sagittal section. III, Peaks superimposed on a 3-D reconstruction of the brain in a lateral oblique angle with the enlarged area showing the region in the posteroventral part of the middle frontal gyrus at the junction of the inferior frontal sulcus (IFS) and inferior PCS (IPCS), i.e., where area 8Av is located (Petrides and Pandya, 1999; Petrides, 2019).
- Figure 5.
Series of coronal (A) an sagittal (B) sections illustrating in the in the top rows voxels whose activity is significant in the ‘conditional eye-movement MINUS control eye-movement’-contrast in hot colors and in the bottom rows (identical sections) voxels whose activity is significant in the ‘eye-movement condition MINUS fixation’-contrast in spectral colors. The detailed illustration shows that the significant clusters are clearly spatially distinct: activity associated with the “eye movement condition MINUS fixation” contrast is found only on the posterior bank of the inferior PCS and the precentral gyrus, whereas activity associated with the “conditional eye movement MINUS control eye movement” contrast is found only in the ventro-caudal middle frontal gyrus, rostral to the inferior PCS. The vertical green lines in B provide a reference to emphasize the separation of these peaks along the y-axis.
- Figure 6.
Location of the relevant functional areas in the human brain as demonstrated in the current functional neuroimaging study. The regions are comparable to those illustrated in the monkey brain in Figure 1. A, 3-D reconstruction of the average MNI human brain adapted from Petrides (2019). B, Outline of cytoarchitectonic areas of the human brain based on a comparative cytoarchitectonic study of macaque monkey and human frontal cortex (Petrides and Pandya, 1999). The three eye movement-related peaks identified in the present fMRI experiment are shown in red: the FEF/sPCS, SEF, and PMVe/iPCS, and the conditional visual selection (CVS) peak is shown in blue. CS: central sulcus; CVS: Conditional Visual Selection in area 8Av in the posterior middle frontal gyrus; PMVe: Premotor Eye-area; FEF: Frontal Eye Field area; LF: lateral fissure; IFS: inferior frontal sulcus; IPCS: inferior precentral sulcus; SEF: Supplementary Eye Field area; SFS: superior frontal sulcus; SPCS: superior precentral sulcus.
Tables
- Table 1
Significant function activation peaks in area 8Av and the FEFs in the fMRI experiment
Right hemisphere Structure Coordinates t value fMRI contrast x y z CVS/8Av 43 18 37 7.6* Conditional minus control eye movement PMVe/iPCS 56 4 38 7.9* Control eye movement minus fixation FEF/sPCS 26 –12 42 4.2* Control eye movement minus fixation SEF 05 –12 63 4.2* Control eye movement minus fixation Left hemisphere Structure Coordinates t value fMRI contrast x y z CVS/8Av –32 18 26 6.1* Conditional minus control eye movement PMVe/iPCS –50 0 37 5.7* Control eye movement minus fixation FEF/sPCS –31 –13 47 2.1 Control eye movement minus fixation SEF –01 –11 62 4.1* Control eye movement minus fixation CVS/8Av: conditional visual selection in area 8Av in the posterior middle frontal gyrus; iPCS: inferior PCS eye area; PMVe: premotor eye-area; FEF: frontal eye field area; SEF: supplementary eye field area; sPCS: superior PCS eye area; *p cor < 0.05.
Conditional minus control eye movement Coordinates t value x y z 37 40 14 5.4 0 30 13 6.7 38 26 10 4.8 2 12 –15 7.6 27 4 –25 4.1 –26 –14 –18 4.5 2 –32 35 5.5 60 –42 6 5.5 –34 –52 –9 5.2 –36 –54 63 5.1 –34 –64 56 4.8 –14 –72 30 6.9 5 –74 23 5.9 –10 –74 2 5.7 10 –76 –4 5.9 –28 –82 14 5.5 Control eye movement minus fixation Coordinates t value x y z –53 0 –1 4.4 49 –6 –12 5.3 63 –42 8 6.8 42 –42 –15 5.7 20 –62 32 8.8 –32 –64 56 13.8 33 –64 52 12.6 27 –64 –11 12.0 –25 –68 –18 11.4 30 –88 14 11.3 –28 –88 20 11.3
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