Do you see these words in colour?

Synaesthesia may be linked to a hyper-excitable brain, new research from the University of Oxford suggests.

Researchers used brain stimulation techniques on people who “see” colours when reading numbers or words. They investigated activity in the visual-processing part of their brain, then compared the results to people without synaesthesia.

They found that people with synaesthesia had a higher level of “excitability” in their primary visual cortex. It took less stimulation for neurons in this part of the brain to fire.

Changing the excitability could increase or lessen the effects of the synaesthesia, researchers found.

The study is published in the journal Current Biology.

Read more at University of Oxford