title: High-field FMRI reveals brain activation patterns underlying saccade execution in the human superior colliculus.
abstract: BACKGROUND
  The superior colliculus (SC) has been shown to play a crucial role in the initiation and coordination of eye- and head-movements. The knowledge about the function of this structure is mainly based on single-unit recordings in animals with relatively few neuroimaging studies investigating eye-movement related brain activity in humans.
  
  
  RESULTS
  The present study employed high-field (7 Tesla) functional magnetic resonance imaging (fMRI) to investigate SC responses during endogenously cued saccades in humans. In response to centrally presented instructional cues, subjects either performed saccades away from (centrifugal) or towards (centripetal) the center of straight gaze or maintained fixation at the center position. Compared to central fixation, the execution of saccades elicited hemodynamic activity within a network of cortical and subcortical areas that included the SC, lateral geniculate nucleus (LGN), occipital cortex, striatum, and the pulvinar.
  
  
  CONCLUSIONS
  Activity in the SC was enhanced contralateral to the direction of the saccade (i.e., greater activity in the right as compared to left SC during leftward saccades and vice versa) during both centrifugal and centripetal saccades, thereby demonstrating that the contralateral predominance for saccade execution that has been shown to exist in animals is also present in the human SC. In addition, centrifugal saccades elicited greater activity in the SC than did centripetal saccades, while also being accompanied by an enhanced deactivation within the prefrontal default-mode network. This pattern of brain activity might reflect the reduced processing effort required to move the eyes toward as compared to away from the center of straight gaze, a position that might serve as a spatial baseline in which the retinotopic and craniotopic reference frames are aligned.
authors.affiliation: Department of Neurology, Otto-von-Guericke-University, Magdeburg, Germany. ruth.krebs@duke.edu
authors.forename: Ruth M
authors.initials: RM
authors.lastname: Krebs
authors.forename: Marty G
authors.initials: MG
authors.lastname: Woldorff
authors.forename: Claus
authors.initials: C
authors.lastname: Tempelmann
authors.forename: Nils
authors.initials: N
authors.lastname: Bodammer
authors.forename: Toemme
authors.initials: T
authors.lastname: Noesselt
authors.forename: Carsten N
authors.initials: CN
authors.lastname: Boehler
authors.forename: Henning
authors.initials: H
authors.lastname: Scheich
authors.forename: Jens-Max
authors.initials: JM
authors.lastname: Hopf
authors.forename: Emrah
authors.initials: E
authors.lastname: Duzel
authors.forename: Hans-Jochen
authors.initials: HJ
authors.lastname: Heinze
authors.forename: Mircea A
authors.initials: MA
authors.lastname: Schoenfeld
mesh_terms: D000328:Adult; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D012438:Saccades; D013477:Superior Colliculi / Q000502:physiology*