title: Cortical activation in hemianopia after stroke.
abstract: Changes in neuronal activity of the visual cortex have been described in patients with hemianopia. The anatomical areas that are involved in neuroplastic changes have not been studied in a larger group of stroke patients with a homogenous structural pathology of the visual cortex. Brain activation was measured in 13 patients with a single ischemic lesion of the striate cortex and partially recovered hemianopia and in 13 age-matched control subjects using blood oxygen level dependent (BOLD) functional magnetic resonance imaging (fMRI). Differences in activation between rest and visual hemifield stimulation were assessed with statistical parametric mapping using group and multi-group studies. In normal subjects, the most significant activation was found in the contralateral primary visual cortex (area 17) and bilaterally in the extrastriate cortex (areas 18 and 19). In patients, these areas were also activated when the intact hemifield was stimulated. During stimulation of the hemianopic side, bilateral activation was seen within the extrastriate cortex, stronger in the ipsilateral (contralesional) hemisphere. Stimulation of the hemianopic visual field is associated with ipsilateral activation of the extrastriate visual cortex. This pattern of activation suggests extensive neuronal plasticity within the visual cortex after postgeniculate ischemic lesions and may have implications for therapeutic interventions.
authors: Neurologische Klinik und Poliklinik, Universitätsklinikum Essen, Germany. gereon.nelles@uni-due.de
authors: Gereon
authors: G
authors: Nelles
authors: Armin
authors: A
authors: de Greiff
authors: Anja
authors: A
authors: Pscherer
authors: Michael
authors: M
authors: Forsting
authors: Horst
authors: H
authors: Gerhard
authors: Joachim
authors: J
authors: Esser
authors: H Christoph
authors: HC
authors: Diener
mesh_terms: D000328:Adult; D000368:Aged; D001931:Brain Mapping; D002560:Cerebrovascular Circulation / Q000502:physiology; D005074:Evoked Potentials, Visual / Q000502:physiology; D005260:Female; D007839:Functional Laterality / Q000502:physiology; D006423:Hemianopsia / Q000175:diagnosis* / Q000503:physiopathology*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009473:Neuronal Plasticity / Q000502:physiology; D010296:Parietal Lobe / Q000033:anatomy & histology / Q000503:physiopathology; D010364:Pattern Recognition, Visual / Q000502:physiology; D010775:Photic Stimulation; D020127:Recovery of Function / Q000502:physiology; D020521:Stroke / Q000150:complications* / Q000503:physiopathology; D014793:Visual Cortex / Q000033:anatomy & histology / Q000503:physiopathology*; D014794:Visual Fields / Q000502:physiology; D014795:Visual Pathways / Q000033:anatomy & histology / Q000503:physiopathology*; D014796:Visual Perception / Q000502:physiology