Effect of TMS on oculomotor behavior but not perceptual stability during smooth pursuit eye movements.
During smooth pursuit eye movements, we do not mistake the shift of the retinal image induced by the visual background for motion of the world around us but instead perceive a stable world. The goal of this study was to search for the neuronal substrates providing perceptual stability. To this end, pursuit eye movements across a background stimulus and perceptual stability were measured in the absence and presence, respectively, of transcranial magnetic stimulation (TMS) applied to 6 different brain regions, that is, primary visual cortex (V1), area MT+/V5, left and right temporoparietal junctions (TPJs), medial parieto-occipital cortex (POC), and the lateral cerebellum (LC). Stimulation of MT+/V5 and the cerebellum induced significant decreases in pursuit gain independent of background presentation, whereas stimulation of TPJ impaired the suppression of the optokinetic reflex induced by background stimulation. In contrast to changes in pursuit, only nonsignificant modifications in perceptual stability were observed. We conclude that MT+/V5, TPJ, and the LC contribute to pursuit eye movements and that TPJ supports the suppression of optokinesis. The lack of significant influences of TMS on perception suggests that motion perception invariance is not based on a localized but rather a highly distributed network featuring parallel processing.
Haarmeier
Thomas
T
Department of Cognitive Neurology and Department of General Neurology, Hertie-Institute for Clinical Brain Research, University of Tübingen, 72076 Tübingen, Germany. thomas.haarmeier@uni-tuebingen.de
Kammer
Thomas
T
D000328:Adult; D001921:Brain / Q000033:anatomy & histology / Q000502:physiology*; D001931:Brain Mapping / Q000379:methods; D005260:Female; D006801:Humans; D008297:Male; D017120:Nystagmus, Optokinetic / Q000502:physiology*; D010775:Photic Stimulation / Q000379:methods; D011698:Pursuit, Smooth / Q000502:physiology*; D050781:Transcranial Magnetic Stimulation / Q000379:methods*; D014793:Visual Cortex / Q000033:anatomy & histology / Q000502:physiology; D014795:Visual Pathways / Q000033:anatomy & histology / Q000502:physiology*; D055815:Young Adult