High-field (3 Tesla) functional magnetic resonance imaging (MRI) was used t
o investigate the cortical circuitry subserving pursuit tracking in humans
and compare it to that for saccadic eye movements. Pursuit performance, rel
ative to visual fixation, elicited activation in three areas known to contr
ibute to eye movements in humans and in nonhuman primates: the frontal eye
field, supplementary eye field, and intraparietal sulcus. It also activated
three medial regions not previously identified in human neuroimaging studi
es of pursuit: the precuneus and the anterior and posterior cingulate corti
ces. All six areas were also activated during saccades. The spatial extent
of activation was similar for saccades and pursuit in all but two regions:
spatial extent was greater for saccades in the superior branch of the front
al eye field and greater for pursuit in posterior cingulate cortex. This se
t of activations for smooth pursuit parallels the network of oculomotor are
as characterized in nonhuman primates and complements recent studies showin
g that common cortical networks subserve oculomotor functions and spatial a
ttention in humans. (C) 1999 Wiley-Liss, Inc.