title: Functional magnetic resonance imaging of sensorimotor transformations in saccades and antisaccades.
abstract: Saccades to peripheral targets require a direct visuomotor transformation. In contrast, antisaccades, saccades in opposite direction of a peripheral target, require more complex transformation processes due to the inversion of the spatial vector. Here, the differential neural mechanisms underlying sensorimotor control in saccades and antisaccades were investigated using functional magnetic resonance imaging (fMRI) at 3T field strength in 22 human volunteers. We combined a task factor (prosaccades: look towards target; antisaccades: look away from target) with a parametric factor of transformation demand (single vs. multiple peripheral targets) in a two-factorial block design. Behaviorally, a greater number of peripheral targets resulted in decreased spatial accuracy and increased reaction times in antisaccades. No effects were seen on the percentage of antisaccade direction errors or on any prosaccade measures. Neurally, a greater number of targets led to increased BOLD signal in the posterior parietal cortex (PPC) bilaterally. This effect was partially qualified by an interaction that extended into somatosensory cortex, indicating greater increases during antisaccades than prosaccades. The results implicate the PPC as a sensorimotor interface that is especially important in nonstandard mapping for antisaccades and point to a supportive role of somatosensory areas in antisaccade sensorimotor control, possibly by means of proprioceptive processes.
authors.affiliation: Department of Psychology, University of Bonn, Kaiser-Karl-Ring 9, 53111 Bonn, Germany; Department of Systems Neuroscience, University Medical Centre Hamburg-Eppendorf, Martinistraße 52, 20246 Hamburg, Germany. Electronic address: n.herweg@uke.de.
authors.forename: Nora A
authors.initials: NA
authors.lastname: Herweg
authors.affiliation: Department of Epileptology, University Hospital Bonn, Sigmund-Freud-Straße 25, 53127 Bonn, Germany; Centre for Economics and Neuroscience, University of Bonn, Nachtigallenweg 86, 53127 Bonn, Germany. Electronic address: bweber@lifeandbrain.com.
authors.forename: Bernd
authors.initials: B
authors.lastname: Weber
authors.affiliation: Department of Psychology, University of Bonn, Kaiser-Karl-Ring 9, 53111 Bonn, Germany. Electronic address: kasparbauer@uni-bonn.de.
authors.forename: Anna
authors.initials: A
authors.lastname: Kasparbauer
authors.affiliation: Department of Psychology, University of Bonn, Kaiser-Karl-Ring 9, 53111 Bonn, Germany. Electronic address: imeyhoefer@uni-bonn.de.
authors.forename: Inga
authors.initials: I
authors.lastname: Meyhöfer
authors.affiliation: Department of Psychology, University of Bonn, Kaiser-Karl-Ring 9, 53111 Bonn, Germany. Electronic address: maria.steffens@uni-bonn.de.
authors.forename: Maria
authors.initials: M
authors.lastname: Steffens
authors.affiliation: University Mental Health Research Institute, Soranou Efesiou 2, Athens 11527, Greece. Electronic address: smyrnis@med.uoa.gr.
authors.forename: Nikos
authors.initials: N
authors.lastname: Smyrnis
authors.affiliation: Department of Psychology, University of Bonn, Kaiser-Karl-Ring 9, 53111 Bonn, Germany. Electronic address: ulrich.ettinger@uni-bonn.de.
authors.forename: Ulrich
authors.initials: U
authors.lastname: Ettinger
mesh_terms: D000328:Adult; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D012438:Saccades / Q000502:physiology*; D066191:Sensorimotor Cortex / Q000502:physiology*; D055815:Young Adult
keywords: Dorsal stream; Eye movements; Parietal cortex; Sensorimotor transformation; fMRI