title: STN-DBS Reduces Saccadic Hypometria but Not Visuospatial Bias in Parkinson's Disease Patients.
abstract: In contrast to its well-established role in alleviating skeleto-motor symptoms in Parkinson's disease, little is known about the impact of deep brain stimulation (DBS) of the subthalamic nucleus (STN) on oculomotor control and attention. Eye-tracking data of 17 patients with left-hemibody symptom onset was compared with 17 age-matched control subjects. Free-viewing of natural images was assessed without stimulation as baseline and during bilateral DBS. To examine the involvement of ventral STN territories in oculomotion and spatial attention, we employed unilateral stimulation via the left and right ventralmost contacts respectively. When DBS was off, patients showed shorter saccades and a rightward viewing bias compared with controls. Bilateral stimulation in therapeutic settings improved saccadic hypometria but not the visuospatial bias. At a group level, unilateral ventral stimulation yielded no consistent effects. However, the evaluation of electrode position within normalized MNI coordinate space revealed that the extent of early exploration bias correlated with the precise stimulation site within the left subthalamic area. These results suggest that oculomotor impairments "but not higher-level exploration patterns" are effectively ameliorable by DBS in therapeutic settings. Our findings highlight the relevance of the STN topography in selecting contacts for chronic stimulation especially upon appearance of visuospatial attention deficits.
authors.affiliation: Institute of Cognitive Science, University of OsnabrückOsnabrück, Germany; Medical Research Council Brain Network Dynamics Unit, University of OxfordOxford, UK; Nuffield Department of Clinical Neurosciences, John Radcliffe Hospital, University of OxfordOxford, UK.
authors.forename: Petra
authors.initials: P
authors.lastname: Fischer
authors.affiliation: Institute of Cognitive Science, University of Osnabrück Osnabrück, Germany.
authors.forename: José P
authors.initials: JP
authors.lastname: Ossandón
authors.affiliation: Institute of Cognitive Science, University of Osnabrück Osnabrück, Germany.
authors.forename: Johannes
authors.initials: J
authors.lastname: Keyser
authors.affiliation: Department of Neurophysiology and Pathophysiology, University Medical Center Hamburg-Eppendorf Hamburg, Germany.
authors.forename: Alessandro
authors.initials: A
authors.lastname: Gulberti
authors.affiliation: Institute of Cognitive Science, University of OsnabrückOsnabrück, Germany; Department of Neurophysiology and Pathophysiology, University Medical Center Hamburg-EppendorfHamburg, Germany.
authors.forename: Niklas
authors.initials: N
authors.lastname: Wilming
authors.affiliation: Department of Neurosurgery, University Medical Center Hamburg-Eppendorf Hamburg, Germany.
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Hamel
authors.affiliation: Department of Neurosurgery, University Medical Center Hamburg-Eppendorf Hamburg, Germany.
authors.forename: Johannes
authors.initials: J
authors.lastname: Köppen
authors.affiliation: Department of Neurology, University Medical Center Hamburg-Eppendorf Hamburg, Germany.
authors.forename: Carsten
authors.initials: C
authors.lastname: Buhmann
authors.affiliation: Department of Neurosurgery, University Medical Center Hamburg-Eppendorf Hamburg, Germany.
authors.forename: Manfred
authors.initials: M
authors.lastname: Westphal
authors.affiliation: Department of Neurology, University Medical Center Hamburg-Eppendorf Hamburg, Germany.
authors.forename: Christian
authors.initials: C
authors.lastname: Gerloff
authors.affiliation: Department of Neurophysiology and Pathophysiology, University Medical Center Hamburg-Eppendorf Hamburg, Germany.
authors.forename: Christian K E
authors.initials: CK
authors.lastname: Moll
authors.affiliation: Department of Neurophysiology and Pathophysiology, University Medical Center Hamburg-Eppendorf Hamburg, Germany.
authors.forename: Andreas K
authors.initials: AK
authors.lastname: Engel
authors.affiliation: Institute of Cognitive Science, University of OsnabrückOsnabrück, Germany; Department of Neurophysiology and Pathophysiology, University Medical Center Hamburg-EppendorfHamburg, Germany.
authors.forename: Peter
authors.initials: P
authors.lastname: König
keywords: basal ganglia; deep brain stimulation; neglect; oculomotor control; subthalamic nucleus; unilateral stimulation; viewing bias; visual attention