Our brains do not have the resources to process all incoming sensory information to the same degree. Therefore, we need to select only some aspects of this information for deeper processing. This is where selective attention comes in. Selective attention is a kind of gatekeeper of our consciousness that lets in the information we concentrate on and attenuates or even completely filters out the rest. Usually, this process is highly helpful but sometimes the gatekeeper appears to become too selective when the attention system goes awry due to brain injury. This condition is called the spatial neglect syndrome.
Neglect can result from damage to the parietal cortices, more commonly in the right than in the left brain hemisphere. Neglect patients have great difficulties in attending to visual information on the side opposite to their brain lesion (i.e. typically to the left side of their visual field). A neglect patient may, for example, be unable to read the left side of the newspaper, or leave the left side of their face unshaven. Neglect is a debilitating condition and ways to alleviate its symptoms are sorely needed.
There is evidence that positive emotions induced by music can increase the breadth of visual selective attention in healthy participants. Thus, music could perhaps also help neglect patients attend to the neglected side of their visual field. Davic De Soto et al. tested this idea in three neglect patients. The patients performed various tests that are sensitive to neglect while listening to self-selected music they liked (for example, the country singer Kenny Rogers or jazz-swing singer Frank Sinatra) or music that they did not particularly enjoy (the indie rock group Sonic Youth and the punk band The Ramones) or in silence. Relative to the silence and non-preferred music conditions, the patients performed significantly better on the tests while listening to the preferred music. Thus, the study suggests that music that induces positive emotions may benefit neglect patients. It is noteworthy that the musical style did not seem to matter as long as the patient liked the music. The sample size of the study was very small but the results still provide encouraging initial evidence that music could some day provide an easy, cheap and pleasant way of alleviating neglect symptoms.
More recently, another research group carried out a similar but larger scale study in 19 neglect patients. The patients performed different tests of neglect symptoms while listening to pleasant or unpleasant music or white noise. As you might have guessed, the results showed that listening to pleasant music improved performance in the tests. Thus, the results of this second study converge with the results from De Soto’s team and provide additional evidence for the benefits of music-induced positive emotions in neglect patients. More research is needed on the long-term effects of music listening in neglect rehabilitation, and on the neural mechanisms that underlie these effects.
A recent study took a different approach to investigate the ways in which music could be incorporated in treating neglect symptoms. In this study, stroke patients with and without neglect as well as healthy control participants played descending scales on a keyboard (i.e. from right to left on the keyboard). The keyboard produced either congruent, correct sounds, random sounds or no sounds at all. Overall, the neglect patients tended not to go as far left on the keyboard as the two other groups. However, in the condition where the keyboard provided congruent auditory feedback, these symptoms were greatly reduced. Thus, auditory feedback in the form of musical scales increased the likelihood that neglect patients explored a greater amount of space on their left side. The authors suggest that the task may have activated preserved auditory and spatial representations of the successive sounds of the scales, and thereby resulted in a more extensive spatial exploration.
These studies add to the literature on the various ways music can have beneficial effects on rehabilitation of neurological conditions, and encourage attempts to develop systematic musical interventions for such conditions. It is important to note that music is no magic pill and the mystery that surrounds the health benefits of music may be counterproductive for the adoption of musical activities as a part of treatment protocols. Therefore, more research on the underlying mechanisms is needed to understand these effects more thoroughly, and for us to be better able to apply them in rehabilitation.
written by ketki karanam
Bernardi, N. F., Cioffi, M. C., Ronchi, R., Maravita, A., Bricolo, E., Zigiotto, L., … Vallar, G. (2015). Improving left spatial neglect through music scale playing. J Neuropsychol, n/a–n/a. doi:10.1111/jnp.12078
Chen, M.-C., Tsai, P.-L., Huang, Y.-T., & Lin, K. (2012). Pleasant music improves visual attention in patients with unilateral neglect after stroke. Brain Injury, 27(1), 75–82. doi:10.3109/02699052.2012.722255
Soto, D., Funes, M. J., Guzman-Garcia, A., Warbrick, T., Rotshtein, P., & Humphreys, G. W. (2009). Pleasant music overcomes the loss of awareness in patients with visual neglect. Proceedings of the National Academy of Sciences, 106(14), 6011–6016. doi:10.1073/pnas.0811681106
Wadlinger, H. A., & Isaacowitz, D. M. (2006). Positive mood broadens visual attention to positive stimuli. Motiv Emot, 30(1), 87–99. doi:10.1007/s11031-006-9021-1