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We investigated single-word reading in normal subjects and patients with alexia following a left occipital infarct, using PET. The most posterior brain region to show a lateralized response was at the left occipitotemporal junction, in the inferior temporal gyrus. This region was activated when normal subjects, patients with hemianopic alexia and patients(More)
OBJECTIVE An acquired right-sided homonymous hemianopia can result in slowed left-to-right text reading, called hemianopic alexia (HA). Patients with HA lack essential visual information to help guide ensuing reading fixations. We tested two hypotheses: first, that practice with a visual rehabilitation method that induced small-field optokinetic nystagmus(More)
Unilateral damage to the lateral occipital region in humans can give rise to impaired motion perception in the contralateral visual field [Plant et al. (1993), Brain, 116, 1303-1335]. We report the following characteristics of the residual vision. (i) Spatial acuity and spatial frequency discrimination are not affected. (ii) Contrast thresholds for(More)
Following an episode of optic neuritis, thinning of the retinal nerve fibre layer, which indicates axonal loss, is observed using optical coherence tomography. The longitudinal course of the retinal changes has not been well characterized. We performed a serial optical coherence tomography study in patients presenting with optic neuritis in order to define(More)
OBJECTIVES Recovery to normal or near normal visual acuity is usual after acute demyelinating optic neuritis, despite the frequent persistence of conduction abnormalities as evidenced by the visual evoked potential (VEP). This raises the possibility that cortical adaptation to a persistently abnormal input contributes to the recovery process. The objective(More)
Diffusion tensor magnetic resonance imaging (DT-MRI) provides in vivo information about the pathology of multiple sclerosis lesions. Increases in mean diffusivity (MD) and reductions in fractional anisotropy (FA) have been found and may represent axonal disruption. The optic nerve is an ideal structure for study by DT-MRI but previous clinical studies did(More)
A comparison of sensitivities to chromatic and luminance stimuli has been carried out in patients with a past history of optic neuritis. Patients were selected with differing degrees of stable residual visual deficits, and with marked interocular differences in sensitivity. Threshold contrast sensitivity was measured to sinusoidal luminance gratings and to(More)
We describe the clinical characteristics and early natural history of a form of inflammatory optic neuropathy which is frequently bilateral and often painful, and is characterized by relapses and remissions. MRI scans of the brain are normal and those of the optic nerves often, but not always, show high signal abnormalities which enhance. The symptoms and(More)
The effect of increasing temporal frequency on contrast sensitivity anomalies in unilateral optic neuritis has been investigated. For 4 c/deg gratings no change in the deficit was observed at any temporal frequency whereas there was a tendency for the deficit to decrease with increase in temporal frequency for 0-5 c/deg gratings. The latter effect was not(More)
BACKGROUND Medically unexplained visual loss occurs in 1 to 5% of patients attending ophthalmology clinics and for many it runs a chronic course. A psychogenic aetiology is presumed in such cases, but little is known about the underlying neural mechanisms. Recent studies have established the value of functional magnetic resonance imaging (fMRI) in(More)