**5. Clinical and therapeutic applications**

To stretch further our hypothesis about music-induced neuroplastic adaptation, music, as a cognitive-demanding activity stimulating neuroplasticity, may be able to slow down, arrest or even reverse the detrimental effects of ageing on learning and memory capacity of the elderly [33]. Recent studies have provided evidence that music-induced plasticity may help also to overcome neurological impairments, such as neurodevelopmental disorders and acquired brain injuries [56]. For instance, attentive music listening recruits multiple forms of working memory, attention, semantic processing, target detection and motor function, relying mainly on bilateral brain areas—superior temporal gyrus, intraparietal sulcus, precentral sulcus, inferior sulcus and gyrus, and frontal operculum—which all serve general functions rather than music-specific cortical regions [87, 88]. Complex musical tasks, moreover, engage the co-activation of many processes involving widely distributed and partly interchangeable substrates of the brain [89]. This may explain, to some extent, the sparing of some musical functions in cases of progressive destruction of some areas in degenerative diseases of the brain. This has been shown most typically in the case of Alzheimer's disease (AD), which is characterised by a general and progressive decline in cognitive function, with the first symptom as an impaired episodic memory. Music, in this case, has been reported as one of the domains in which general skill and memory are preserved in spite of otherwise severe impairment [90]. This preserved musical processing, moreover, is not limited to procedural memory but often includes also stories of music, which can be used as an effective mnemonic device [91].

external stimuli or demands, the brain is constantly sharing information. It thus consolidates recent learning and maintains the association of activity of brain areas that are likely to be

Initial research suggests that musical training might enhance this pattern of increased restingstate connectivity by triggering heightened connections at a functional level between those brain regions that are structurally and functionally altered as the result of training. This is manifested even during a task-free condition, pointing to the "silent" imprint of musical training on the human brain [35]. Research on the differences between musicians and non-musicians in their functional connectivity during rest, however, is still in its infancy [10, 82]. By selecting predefined seed regions for computing connectivity analysis, increased connectivity between contralateral homologue regions has been found in musicians between prefrontal, temporal, inferior-parietal and premotor areas [35]. It is to be questioned, however, whether the study of predefined regions or seed regions does not neglect residual whole-brain dynamics. However, for the seed regions for which plastic changes in musicians have been found already—as evidenced by increased grey matter volume—connectivity analyses have revealed brain areas whose resting-state time series activity was more closely synchronised with one of them. Four networks were found to supply integrative interpretations for the cognitive functions during musical practice: (i) autobiographical memory-related regions belonging to the default mode network, recruited by the encoding, storage and recall of melodies with an emotional and biographical quality; (ii) areas that belong to the salience network with access to semantic memory that is related to the storage of music in terms of verbal labels and auditory structure; (iii) regions that are implied in language processing and the resting-state auditory network and (iv) structures that belong to the executive control network, and which could subserve the motor modulation required for an emotionally expressive interpretation of music. The question whether this practice-related plasticity is triggered by local grey matter volume, however, is not yet satisfactorily resolved, in the sense that other variables may be implicated in the expertise-related resting-state functional reorganisation of musician's plastic brain [10].

To stretch further our hypothesis about music-induced neuroplastic adaptation, music, as a cognitive-demanding activity stimulating neuroplasticity, may be able to slow down, arrest or even reverse the detrimental effects of ageing on learning and memory capacity of the elderly [33]. Recent studies have provided evidence that music-induced plasticity may help also to overcome neurological impairments, such as neurodevelopmental disorders and acquired brain injuries [56]. For instance, attentive music listening recruits multiple forms of working memory, attention, semantic processing, target detection and motor function, relying mainly on bilateral brain areas—superior temporal gyrus, intraparietal sulcus, precentral sulcus, inferior sulcus and gyrus, and frontal operculum—which all serve general functions rather than music-specific cortical regions [87, 88]. Complex musical tasks, moreover, engage the co-activation of many processes involving widely distributed and partly interchangeable substrates of the brain [89]. This may explain, to some extent, the sparing of some musical functions in cases of progressive

used together in future [86].

94 Neuroplasticity - Insights of Neural Reorganization

**5. Clinical and therapeutic applications**

Hence, music may shape the development of normal and healthy human beings over the lifespan, but its potential as a non-pharmacological interventional aid for caregivers to help the cognitive and emotional capacity of patients with neurological and psychiatric brain disorders is receiving growing interest [15]. The use of resting-state fMRI techniques, e.g., with a main focus on the default mode network, seems to be well-suited to examine possible functional disconnectivity effects in disorders such as Alzheimer's disease, depression, dementia and schizophrenia. Also, other neurogenerative diseases like multiple sclerosis and amyotrophic lateral sclerosis seem to show changed connectivity in the default network as well as in other resting-state networks [78]. This may suggest that neurodegenerative diseases would attack interconnected cortical networks rather than single regions in the brain [92] and can thus be targets of a music intervention aimed at stabilising abnormal patterns of functional connectivity between compromised brain areas.

Music has been used already as a treatment for some psychiatric and neurological pathologies, such as schizophrenic disorders, Alzheimer's disease, Parkinson's disease, cerebral ischemia, pain, autism, anxiety and depression [15]. Music, furthermore, has been reported to improve also the well-being and cognitive functions in healthy adults, such as autobiographical memory, semantic memory, language ability and cognitive functions, and to alleviate neuropsychiatric symptoms, such as agitation, apathy, depression and anxiety (see [39] for an overview). Effects of music on AD are exemplary of the mechanisms that might mediate the impact of music on human well-being. Latent benefits of musical mnemonics as an aid to standard mnemonic methods, which may seem to be insufficient for AD patients, have been reported (for a review, see [15]). The mechanisms behind these memory-enhancing effects, however, are still not fully understood, but there is strong evidence for a benefit of music as a mnemonic device in a variety of clinical settings [91]. A possible explanation is that the areas of the brain associated with music cognition are preferentially spared in the case of AD. It has been suggested that procedural memory and priming effects for musical stimuli remain intact, whereas shortterm and long-term episodic memory for melodic excerpts is impaired [93].

This dissociation between memory and general performance in AD patients holds in particular for listening to their favourite songs, which seems to recruit previously encoded memories. These memories seem to support and sustain brain introspection via connectivity within the default mode network and also to effectively reprocess autobiographic and episodic memories [84]. An additional explanation for this dissociation is that in patients with general cortical and hippocampal atrophy, which impairs standard episodic learning, musically-associated stimuli allow for a more diversified encoding. Music processing, in that case, encompasses a neural network that is recruiting from multiple areas of the brain, including cortical as well as subcortical areas. Musical stimuli and stimuli accompanied by music seem to create a more robust association at the stage of encoding and support a more composite encoding and retrieval process by inducing oscillatory synchrony in those neural networks that are associated with learning and memory [91, 94].

**Author details**

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Mark Reybrouck1,2\*, Peter Vuust3

and Elvira Brattico<sup>3</sup>

Music and Brain Plasticity: How Sounds Trigger Neurogenerative Adaptations

http://dx.doi.org/10.5772/intechopen.74318

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3 Department of Clinical Medicine, Center for Music in the Brain, Aarhus University and

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1 Musicology Research Group, KU Leuven – University of Leuven, Belgium

2 IPEM Institute for Systematic Musicology, Ghent University, Belgium

\*Address all correspondence to: mark.reybrouck@kuleuven.be

The Royal Academy of Music, Aarhus/Aalborg, Denmark
