title: Neural correlates of visual motion processing without awareness in patients with striate cortex and pulvinar lesions.
abstract: Patients with striate cortex lesions experience visual perception loss in the contralateral visual field. In few patients, however, stimuli within the blind field can lead to unconscious (blindsight) or even conscious perception when the stimuli are moving (Riddoch syndrome). Using functional magnetic resonance imaging (fMRI), we investigated the neural responses elicited by motion stimulation in the sighted and blind visual fields of eight patients with lesions of the striate cortex. Importantly, repeated testing ensured that none of the patients exhibited blindsight or a Riddoch syndrome. Three patients had additional lesions in the ipsilesional pulvinar. For blind visual field stimulation, great care was given that the moving stimulus was precisely presented within the borders of the scotoma. In six of eight patients, the stimulation within the scotoma elicited hemodynamic activity in area human middle temporal (hMT) while no activity was observed within the ipsilateral lesioned area of the striate cortex. One of the two patients in whom no ipsilesional activity was observed had an extensive lesion including massive subcortical damage. The other patient had an additional focal lesion within the lateral inferior pulvinar. Fiber-tracking based on anatomical and functional markers (hMT and Pulvinar) on individual diffusion tensor imaging (DTI) data from each patient revealed the structural integrity of subcortical pathways in all but the patient with the extensive subcortical lesion. These results provide clear evidence for the robustness of direct subcortical pathways from the pulvinar to area hMT in patients with striate cortex lesions and demonstrate that ipsilesional activity in area hMT is completely independent of conscious perception.
authors.affiliation: Department of Neurology, Otto-von-Guericke University, Magdeburg, Germany.
authors.forename: Maria
authors.initials: M
authors.lastname: Barleben
authors.forename: Christian M
authors.initials: CM
authors.lastname: Stoppel
authors.forename: Jörn
authors.initials: J
authors.lastname: Kaufmann
authors.forename: Christian
authors.initials: C
authors.lastname: Merkel
authors.forename: Thoralf
authors.initials: T
authors.lastname: Wecke
authors.forename: Michael
authors.initials: M
authors.lastname: Goertler
authors.forename: Hans-Jochen
authors.initials: HJ
authors.lastname: Heinze
authors.forename: Jens-Max
authors.initials: JM
authors.lastname: Hopf
authors.forename: Mircea A
authors.initials: MA
authors.lastname: Schoenfeld
mesh_terms: D000328:Adult; D000368:Aged; D001364:Awareness; D001931:Brain Mapping; D002560:Cerebrovascular Circulation / Q000502:physiology; D056324:Diffusion Tensor Imaging; D005260:Female; D007839:Functional Laterality; D006801:Humans; D020762:Infarction, Posterior Cerebral Artery / Q000150:complications / Q000473:pathology / Q000503:physiopathology; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009039:Motion Perception / Q000502:physiology*; D010468:Perceptual Disorders / Q000209:etiology / Q000473:pathology / Q000503:physiopathology*; D010775:Photic Stimulation / Q000379:methods; D020649:Pulvinar / Q000473:pathology / Q000503:physiopathology*; D014786:Vision Disorders / Q000209:etiology / Q000473:pathology / Q000503:physiopathology*; D014793:Visual Cortex / Q000473:pathology / Q000503:physiopathology*; D014794:Visual Fields; D014795:Visual Pathways / Q000473:pathology / Q000503:physiopathology; D055815:Young Adult
keywords: V1 lesion; awareness; motion processing; subcortical pathways