title: Cortical functional modifications following optic neuritis.
abstract: BACKGROUND
  We have recently suggested that delayed visual evoked potential (VEP) latencies in the fellow eye (FE) of optic neuritis patients reflect a cortical adaptive process, to compensate for the delayed arrival of visual information via the affected eye (AE).
  
  
  OBJECTIVE
  To define the cortical mechanism that underlies this adaptive process.
  
  
  METHODS
  Cortical activations to moving stimuli and connectivity patterns within the visual network were tested using functional magnetic resonance imaging (MRI) in 11 recovered optic neuritis patients and in 11 matched controls.
  
  
  RESULTS
  Reduced cortical activation in early but not in higher visual areas was seen in both eyes, compared to controls. VEP latencies in the AEs inversely correlated with activation in motion-related visual cortices. Inter-eye differences in VEP latencies inversely correlated with cortical activation following FE stimulation, throughout the visual hierarchy. Functional correlation between visual regions was more pronounced in the FE compared with the AE.
  
  
  CONCLUSIONS
  The different correlation patterns between VEP latencies and cortical activation in the AE and FE support different pathophysiology of VEP prolongation in each eye. Similar cortical activation patterns in both eyes and the fact that stronger links between early and higher visual areas were found following FE stimulation suggest a cortical modulatory process in the FE.
authors.affiliation: fMRI Lab, Neurology Department, Hadassah Hebrew University Medical Center, Jerusalem Israel.
authors.forename: Tal
authors.initials: T
authors.lastname: Benoliel
authors.affiliation: fMRI Lab, Neurology Department, Hadassah Hebrew University Medical Center, Jerusalem Israel.
authors.forename: Noa
authors.initials: N
authors.lastname: Raz
authors.affiliation: fMRI Lab, Neurology Department, Hadassah Hebrew University Medical Center, Jerusalem Israel.
authors.forename: Tamir
authors.initials: T
authors.lastname: Ben-Hur
authors.affiliation: fMRI Lab, Neurology Department, Hadassah Hebrew University Medical Center, Jerusalem Israel.
authors.forename: Netta
authors.initials: N
authors.lastname: Levin
mesh_terms: D000293:Adolescent; D000328:Adult; D005074:Evoked Potentials, Visual / Q000502:physiology*; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D009473:Neuronal Plasticity / Q000502:physiology; D009902:Optic Neuritis / Q000503:physiopathology*; D011930:Reaction Time / Q000502:physiology; D014793:Visual Cortex / Q000503:physiopathology*; D055815:Young Adult
keywords: Optic neuritis; VEP; fellow eye; functional MRI; plasticity; visual cortex