Related Experiment Video
Updated: Mar 30, 2026

Dynamic Visual Tests to Identify and Quantify Visual Damage and Repair Following Demyelination in Optic Neuritis Patients
Published on: April 14, 2014
Visual cortical excitability in dementia with Lewy bodies
John-Paul Taylor1, Michael Firbank2, John T O'Brien2
1John-Paul Taylor, MBBS, PhD, MRCPsych, Michael Firbank, PhD, Institute of Neuroscience, Newcastle University, Newcastle upon Tyne; John T. O'Brien, MD, FRCPsych, Department of Psychiatry, University of Cambridge, Cambridge Biomedical Campus, Cambridge, UK john-paul.taylor@ncl.ac.uk.
Abstract:
Alterations in the visual system may underlie visual hallucinations in dementia with Lewy bodies (DLB). However, cortical excitability as measured by transcranial magnetic stimulation (TMS) and functional magnetic resonance imaging (fMRI) activation of lower visual areas (V1-3) to visual stimuli appear normal in DLB. We explored the relationship between TMS-determined phosphene threshold and fMRI-related visual activation and found a positive relationship between the two in controls but a negative one in DLB. This double dissociation suggests a loss of inhibition in the visual system in DLB, which may predispose individuals to visual dysfunction and visual hallucinations.
Related Concept Videos
Visual Agnosia
Dementia
The progression of dementia is generally gradual....
Alzheimer's Disease: Overview
The clinical diagnosis of AD hinges on the presence of memory and other cognitive impairments. Biomarkers, such as changes in Aβ...

