A disorder of colour perception associated with abnormal colour after-images: a defect of the primary visual cortex. Issue 4 (1st October 2001)

• Record Type: Journal Article
• Authors: Chan, D; Crutch, S J; Warrington, E K
• Is Part Of: Journal of neurology, neurosurgery and psychiatry. Volume 71:Issue 4(2001)
• Page Start: 515
• Page End: 517
• Publication Date: 2001-10-01
• Subjects: colour vision -- visual cortex -- Alzheimer's disease; Neurology -- Periodicals; Nervous system -- Surgery -- Periodicals; Psychiatry -- Periodicals; 616.8
• DOI: 10.1136/jnnp.71.4.515
• Languages: English
• ISSNs: 0022-3050

Abstract

Abstract : A 64 year old woman with posterior cortical atrophy secondary to probable Alzheimer's disease is described. Her presenting symptom was of seeing objects as abnormally coloured after prior exposure to a coloured stimulus. Formal testing disclosed that the patient experienced colour after-images of abnormal latency, duration, and amplitude. The demonstration of prolonged colour after-images in a patient with a cortical disease process provides strong evidence that the generation of colour after-images is mediated at least in part by the visual cortex. A mechanism for the generation of colour after-images is proposed in which abnormal prolongation of the images results from excessive rebound inhibition of previously excited wavelength selective neurons in V1. This may occur as a consequence of the relative sparing of inhibitory interneurons in V1 in the context of the degeneration of excitatory neurons that occurs in Alzheimer's disease.