title: Functional magnetic resonance imaging of the cortical response to photic stimulation in humans following optic neuritis recovery.
abstract: Recovery from optic neuritis has been shown to be associated with an abnormal functional MRI (fMRI) response following exposure of the eye to an epoch based (ON-OFF design) flickering photic stimulus. Visual cortex activation is reduced during photic stimulation, whilst extra-occipital areas are extensively activated with a peak blood oxygen level dependent response during the OFF phase of the stimulus paradigm. We performed a further fMRI experiment to determine whether the abnormal extra-occipital response is a phase-specific phenomenon or whether it results from a delayed haemodynamic response. A cohort of patients that recovered from optic neuritis was studied, this time using a longer photic stimulation epoch (40 s). The extra-occipital response again peaked during the baseline condition, indicating that the phenomenon is phase dependent. Our results also reinforce the important findings of extra-occipital activation following optic neuritis which may represent an adaptive reorganization of the cerebral response.
authors.affiliation: NMR Research Unit, Institute of Neurology, Queen Square, London WC1N 3BG, UK.
authors.forename: A T
authors.initials: AT
authors.lastname: Toosy
authors.forename: D J
authors.initials: DJ
authors.lastname: Werring
authors.forename: E T
authors.initials: ET
authors.lastname: Bullmore
authors.forename: G T
authors.initials: GT
authors.lastname: Plant
authors.forename: G J
authors.initials: GJ
authors.lastname: Barker
authors.forename: D H
authors.initials: DH
authors.lastname: Miller
authors.forename: A J
authors.initials: AJ
authors.lastname: Thompson
mesh_terms: D000328:Adult; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D009902:Optic Neuritis / Q000503:physiopathology*; D010775:Photic Stimulation; D020127:Recovery of Function; D014793:Visual Cortex / Q000502:physiology / Q000503:physiopathology*