title: Functional neuroimaging of the oculomotor brainstem network in humans.
abstract: The cortical systems involved in eye movement control in humans have been investigated extensively using fMRI. In contrast, there is virtually no data concerning the functional status of the human oculomotor brainstem nuclei. This lack of evidence has usually been explained by technical constraints of EPI based imaging and anatomical characteristics of the brainstem. Against this assumption, we successfully localised nuclei of the oculomotor system using high-resolution fMRI based on standard EPI sequences in a group of healthy subjects executing reflexive horizontal saccades. A random-effects group analysis revealed task-related BOLD increases in the superior colliculus, the oculomotor nucleus, the abducens nucleus and in the paramedian pontine reticular formation. This group analysis was complemented by individual positive findings in up to 94% of single subject analyses. A visual control paradigm led to increased signal levels in the superior colliculus consistent with its visual properties but no corresponding signal changes in other brainstem nuclei. These results are consistent with findings in animal studies and demonstrate the feasibility to detect BOLD signal increases associated with oculomotor tasks even in the human brainstem using conventional EPI imaging techniques.
authors.affiliation: Division of Neuropsychology, Hertie-Institute for Clinical Brain Research, Eberhard Karls University, Hoppe-Seyler-Str 3, 72076 Tuebingen, Germany.
authors.forename: Walter
authors.initials: W
authors.lastname: Linzenbold
authors.forename: Tobias
authors.initials: T
authors.lastname: Lindig
authors.forename: Marc
authors.initials: M
authors.lastname: Himmelbach
mesh_terms: D000328:Adult; D001931:Brain Mapping; D001933:Brain Stem / Q000502:physiology*; D005133:Eye Movements / Q000502:physiology*; D005260:Female; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008279:Magnetic Resonance Imaging; D008297:Male; D009434:Neural Pathways / Q000502:physiology*; D010775:Photic Stimulation; D055815:Young Adult