Music may have a profound effect
Listening to pleasant music could help restore impaired vision in stroke patients, UK research suggests.
Up to 60% of stroke patients develop impaired visual awareness - a condition known as "visual neglect".
They lose the ability to track objects in their visual field on the side opposite to where their brain has been damaged by the stroke.
The Proceedings of the National Academy of Sciences study suggests music can help ease the problem.
It is caused by damage to areas of the brain critical for the integration of vision, attention and action - not the areas responsible for sight.
In extreme cases, patients with visual neglect may eat only the food on the right side of their plate, or shave only half of their face.
The latest study looked at three patients who had lost awareness of half of their field of vision.
They completed tasks under three conditions: while listening to music they liked, music they did not like, and in silence.
All three patients could identify coloured shapes and red lights in their depleted side of vision much more accurately while they were listening to music of their choice.
One patient could point out light in 65% of cases when listening to his favourite music, but in only 15% of cases when listening to unpleasant music, or silence.
The researchers believe pleasant music generates positive emotions, which may help produce more efficient signalling in the brain, increasing its capacity to process stimuli.
Brain scans confirmed that listening to pleasant music activated areas linked to positive emotional responses, and that activity was coupled with the improvement in patients' performance on the tasks.
Lead researcher Dr David Soto, from Imperial College London, said: "Visual neglect can be a very distressing condition for stroke patients. It has a big effect on their day-to-day lives.
"Our findings suggest that we should think more carefully about the individual emotional factors in patients with visual neglect and in other neurological patients following a stroke.
"Music appears to improve awareness because of its positive emotional effect on the patient, so similar beneficial effects may also be gained by making the patient happy in other ways."
Joanne Murphy, of the Stroke Association said: "This is very interesting research that indicates that a positive emotional state can help a stroke survivor with an obstacle such as visual neglect.
"We would welcome further research into this and other conditions which could help benefit the 150,000 people affected by stroke each year."