Music was the best medicine for four stroke victims whose cognitive impairments lessened while listening to songs they loved.

The music stimulated neurological pleasure centers adjacent to damaged brain regions, apparently producing a therapeutic crossover effect.

"There seems to be a strong coupling in the brain between emotional and attentional areas," said study co-author David Soto, an Imperial College London neuroscientist. "When emotional areas light up and are activated, the attentional system seems to be more effective as well."

The study, published Monday in the Proceedings of the National Academy of Sciences, resonates with earlier research on the general benefits of music for cognitive deterioration and its specific benefits for stroke victims.

In a prominent paper published last year in Brain, Finnish researchers measured the cognitive recoveries of 60 stroke victims who listened to music, audio books or nothing at all while undergoing standard therapy. Patients in the music group fared best, but mechanisms underlying the improvements remained uncertain.

It seemed possible that the music, which was chosen without regard for patients' musical preferences, produced a beneficial state of heightened mental arousal: patients' ears, and thus their brains, perked up. But it was also possible — as suggested by Soto's findings — that patients happened to like the music, and that benefits were connected to pleasure derived from favorite songs.

"Our ability to select information and perceive information and be aware of what's going on in the world depends on how we feel," said Soto.

Participants in Soto's study had suffered lesions to their brains'

parietal cortex, a region central to visual and spatial processing.

This left them with a condition called visual neglect, in which people lose half their spatial awareness. Victims will sometimes eat food from only one side of their plate, shave one side of their faces, or — as tested in the study — fail to perceive visual prompts on one side of a computer screen.

When Soto's patients listened to music they didn't like, their brains were highly aroused, but they performed poorly on tests of their weakened perceptual side. When listening to their favorite songs, they performed far better, even though their mental arousal was relatively low.

Among the artists favored by the patients were the Flying Burrito

Brothers Band, Frank Sinatra and Kenny Rogers. Songs from the latter artist provided the greatest benefits.

"We were thinking of calling this the Kenny Rogers Effect," said Soto.

The results, said Soto, suggest that something other than sheer activation produced the therapeutic effects. A brain scan of one patient found increased activity in the brain's pleasure centers, which happened to be located beside his damaged parietal cortex.

Soto said that increased releases of dopamine, an emotion-regulating neurotransmitter, may be responsible. "It may lead to an increase of neural resources in these critical damaged brain regions," he said.

The dopamine-boosting drug Levodopa has been used experimentally to treat strokes, but results have been mixed and its side effects are severe. Music is ostensibly a less-toxic source.

University of Helsinki cognitive scientist Teppo Särkämö, a co-author of the Brain study, lauded Soto's methodology, but noted that the small number of patients involved means that "no firm conclusions can yet be drawn about the robustness of the music effect."

Because patients were tested while listening to the music rather than afterwards, he said, "there is no evidence about the possible long-term effects of music-induced positive emotions" on recovery.

Soto next hopes to study the effects of music on more patients, and other stroke-related problems.

Citation: "Pleasant music overcomes the loss of awareness in patients with visual neglect." By David Soto, Mar?a J. Funes, Azucena

Guzman-Garc?a, Tracy Warbrick, Pia Rotshtein, and Glyn W. Humphrey.

Proceedings of the National Academy of Sciences, Vol. 106, No. 12,

March 23, 2009.

*Image: Flickr/Ace Armstrong

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