Stimulation of the visual cortex to reduce hallucinations in the blind

 Stimulation of the visual cortex to reduce hallucinations in the blind

Researchers from Newcastle University and King’s College London tested ‘transcranial direct current stimulation (tDCS) on patients as part of an 18-month study. The technique involves passing a weak electrical current between electrodes placed on a person’s scalp and has been shown to change activity levels in some brain regions. Previous research suggests that loss of information from the eyes causes increased spontaneous activity in the visual cortex hallucinations, which contributes to the appearance of visual hallucinations in Charles Bonnet syndrome (CBS). The study aimed to use tDCS to reduce this activity and return visual cortex hallucinations to normal levels.

The study’s results have shown that stimulation can reduce the frequency of visual hallucinations in people with BCS, especially in individuals with increased levels of spontaneous activity.

Up to half of the people with macular disease experience CNS hallucinations. They can be simple flashes of light, colors, or formless shapes, while many people also see geometric grids and lattices.

Others have reported seeing more complex visual experiences like disembodied heads, small figures in elaborate costumes, and snakes. About a third of people with the syndrome say that the hallucinations can be distressing and disrupt their daily lives.

In the study, 16 people diagnosed with SCC received four consecutive days of active and placebo treatment, with non-invasive stimulation of the visual parts of the brain.

The results show that tDCS may be viable for patients with SCC without significant side effects. However, further work will be required before wider clinical use can be considered.

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