[Position Paper]

Music Therapy and Neuroscience: Opportunities and Challenges

By Julian O’Kelly

Abstract

Human responses to music may be viewed through a neuroscience lens with increasingly sophisticated neuroimaging technology, providing neurological and biomedical measures of psychological states. These developments have been harnessed in collaborative research investigations seeking to develop the therapeutic applications of music. As a consequence of these collaborations, neuroscientific understanding is emerging of how music therapy may support improvements in cognition, movement and emotional regulation, as well as helping us to explore the neurological aspects of therapeutic relationships. This paper provides an overview of this field of investigation, focussing on the significant areas of progress in work with those living with stroke, neurodegenerative conditions, affective disorders, disorders of consciousness, autism, cancer and palliative conditions. Advances, challenges and opportunities associated with using neuroscience methods to develop the evidence base for music therapy will be explored from the perspective of a music therapy clinician and researcher.

Keywords: music therapy, neuroscience, methods, fMRI, EEG, neurophysiological, neurochemical, neurological

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Editorial note: In 2016, Voices hosted a special edition to accompany the launch of a Massive Open Online Course (MOOC) on the topic of "How Music Can Change Your Life". Thirteen authors agreed to develop position papers for the MOOC, with two articles being developed to accompany each of the six topics within it. Each author has highlighted the theorists and researchers who have influenced their thinking, and included references to their own research or music practices where appropriate. These papers have been written with a particular audience in mind—that is, the learners who participate in the MOOC, who may not have had previous readings in any of the fields being canvassed. We hope that you find these articles interesting, whether reading as a MOOC learner, a regular VOICES reader, or someone who is discovering VOICES for the first time.

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Introduction

‘Music…the supreme mystery of the science of man, a mystery that all the various disciplines come up against and which holds the key to their progress.” (Lévi-Strauss, 1970, p.18)

As a clinician, researcher, and manager at various points in my career I have been fascinated by how the profession of music therapy interfaces with neuroscience on many levels, and how this interface can inform our work with diverse clinical populations. Neuroscience involves the study of the nervous system at a molecular, cellular, and systems level. Drawing on cellular and systems models, the related disciplines of neuropsychology, cognitive, and behavioural neuroscience explore how neural systems relate to each other to generate a range of behaviours and cognitive functions. Here, research in brain processes moves to theories on cognitive faculties enabling consciousness, perception, thinking, judgement, and memory, or the mind. In all these areas of brain activity, our experience of music, in particular the way it engages our emotions, memory, cognition, and movement/motor activity are intimately related. A natural consequence of this overlap is the host of research collaborations between neuroscientists, music therapists, and other medical professions outlined in this paper. This evolving field is underpinned by three aspects of neuroscience that are especially helpful to music therapy, enabling clinicians and researchers to:

1. be informed by how and why the brain operates in the way it does, and how acquired, degenerative, or congenital disruption of brain affects human behaviour
2. understand how musical activity and experiences operate at a neural level integrating diverse cortical activity, shaping neuroplasticity, and wide ranging neuro-hormonal activity
3. conduct efficacy and exploratory studies using neuroscience methods to provide indicators of biological states, or biomarkers and understand neural mechanisms associated with the therapeutic process in music therapy

Mindful of space constraints, this paper will explore the implications for the music therapy profession from the literature in this evolving field in the last two areas only, offering readers pointers for further reading throughout. I will also aim to reflect an appreciation that neuroscience methods can only provide one part of the story in relation to how we work and how clients experience music therapy. In doing so I hope to illuminate the research achievements to date, and opportunities afforded by future partnerships, whilst outlining some of the challenges and limits to this field of collaborative enquiry.

Lessons from Neuroscience

Humans are drawn towards music perceived as pleasant – such as the phenomenon of chills, where music activates the same dopamine releasing reward systems involved in eating, sex, and recreational drug use (Salimpoor, Benovoy, Larcher, Dagher, & Zatorre, 2010). Neuroscientists are also fascinated by how humans process, experience, and respond to music, because of the complexity of music as a stimulus, structured as it is multi-dimensionally, requiring the integration of sensory, movement based (motor), attentional, emotional and memory processes, and utilising a vast, bilateral network of brain areas (Särkämö, Tervaniemi, & Huotilainen 2013; Münte, Altenmüller, & Jäncke, 2002). In Figure 1 below, Särkämö et al. (2013) integrate over twenty years of music neuroscience studies to outline the host of brain regions implicated in musical activities. More recently, Norman-Haignere and colleagues (2015) have identified a specific region of the brain responding highly selectively to music, rather than only piggybacking brain regions devoted to non-musical behaviours such as speech, pointing to a potential involvement of this region or neural population in human evolution.

Neuroscience holds the potential of identifying some of the core ingredients, i.e. what works in music therapy, from a perspective shared by mainstream scientific and medical approaches. Fachner (2016) outlined three core ways in which neuroscience methods may be used for music therapy research: (a) in situ studies, where measures are used during music therapy sessions to explore underlying neurological processes; (b) empirical comparisons where neuroimaging and neurological measures provide biomarkers of general changes in brain processes pre and post interventions, and (c) approximations, where methods are focussed on the effects of specific musical features, and findings explored to identify brain based action mechanisms in the music therapy process. Hilleke and colleagues (2005) believe this type of research may address a failing of the music therapy literature, namely the abundance of heterogeneous, sometimes contradictory theoretical approaches that are hard to generalise to a wider multidisciplinary/international audiences.

Music Neuroscience and the Growth in Cross-disciplinary Discourse

Music neuroscience has established itself as a discrete field of enquiry, expanding rapidly in the last 10 years, with organisations such as the Mariani Foundation supporting an international Neuroscience of Music conference series (e.g. Altenmüller et al. 2012; Bigand et al., 2015; Dalla Bella & Penhune, 2009,), which has been studied in detail from a music therapy perspective by Christensen (2012). The increasing use of neuroscience methods by music psychologists, performance experts, and ethnomusicologists is also evident in a range of cross-disciplinary conferences in recent years e.g. the Society for Music Perception and Cognition and International Conference on Music & Emotion proceedings (Luck & Brabant 2013; Schutz, & Russo, 2013). Furthermore, the potential for productive dialogue between music therapy, neuroscience and psychology in the field of neuro-disability has provided the rationale for a biennial series of Music Therapy Advances in Neuro-disability at the Royal Hospital for Neuro-disability (O’Kelly et al., 2014).

Searching some of the major music therapy and music psychology publications for title references to neuroscience or neuro-imaging highlights an exponential growth in interest since 2012, as Figure 2 illustrates. Three open access research topics hosted by Frontiers in Neuroscience and Frontiers in Psychology further underscore a growth in convergent research. The topics, set up jointly by music therapists, neuroscientists and psychologists, have between them published 55 papers featuring collaborations between these disciplines (O’Kelly, Fachner, & Terveniemi, 2016; Magee, Tillman, Perrin, & Shnackers, 2016; Särkämö, Altenmüller, Rodriguez-Fornells & Peretz, 2015).

Neuro-imaging and Neurophysiological Recording Methods

The most common methods of neuroimaging relevant to music therapy are functional magnetic resonance imaging (fMRI) and electroencephalogram (EEG). fMRI explores how different parts of the brain respond to external stimuli (i.e. music) in a resting state, and how the shape and connectivity of brain regions change over time. Blood flow responses to neural activity resulting from a change in blood-oxygen levels (blood oxygenation level dependent or BOLD changes) are measured, providing fine grained 3-D images to a high level of accuracy in terms of locating specifically where brain activity is. However the considerable delay involved in recording the BOLD signal, means fMRI can only be considered as an indirect measure of music perception/processing in real time. Although far less precise at illuminating changes in brain structures and connectivity, EEG methods offer greater sensitivity to the timing of brain activity, recording the faint electrical activity of the brain to millisecond accuracy, and with much less physical restriction than fMRI. EEG uses two reference and 19 or more passive electrodes placed on the scalp, using paste or head caps, in standardised locations corresponding to brain areas. Recordings may be analysed to explore measures of power at different frequency bands (for example theta at 3-7Hz, alpha at 8-12 Hz, and beta at 13-30 Hz), connectivity (i.e. EEG coherence), or the brains immediate responses to complex sensory stimuli such as differences in timbre, or musical incongruities, with miss-match negativity (MMN) methods (for an overview: Shanbao, Tong, & Thankor, 2009).

Neuro-imaging methods used less frequently in the literature include positron emission tomography (PET), where metabolic processes are observed via the detection of gamma rays emitted indirectly by a radio-active tracer, and diffusion tensor imaging (DTI), which maps the diffusion process of water molecules in the brain to reveal microscopic details about tissue architecture. A comprehensive review of these and other methods from a music therapy perspective is provided by Hunt & Legge (2015).

For a neuro-chemistry perspective of this field, Chanda and Levitan’s (2013) review outlined how music can modulate established biological traces, or biomarkers of reward, motivation and pleasure (dopamine), stress and arousal (cortisol), immunity (serotonin), even social affiliation (oxytocin). A further review of these ‘psychoneuroimmunological’ effects of music (Fancourt, Ockelford, & Belai 2014) points to musical activities modulating the behaviour of a host of neurochemical/biological agents: neurotransmitters, hormones, cytokines, lymphocytes, vital signs, and immunoglobulins that are implicated in our stress response and immune levels, although the authors highlight a range of methodological flaws in this field of research.

The autonomic nervous system (ANS), which is part of the peripheral nervous system influencing the function of internal organs, may be recorded to reflect arousal levels related to music. These responses may be considered as relating to an integrated model known as the Central Autonomic Network (Benarroch, 1993) where neuronal structures involved in cognitive, emotional, and autonomic regulation are reflected in heart function measures. However, as with neuro-chemical markers, literature relating ANS responses to emotional stimuli has been critiqued for its incongruities and lack of rigour (Kreibig, 2010). Nonetheless, there is consensus that heart rate (HR) and its variability (HRV) represent activation and suppression of the sympathetic and parasympathetic nervous system (SNS & PNS), or arousal, and the body’s homeostatic break on arousal. HRV may be analysed in time domain measures variability of long or short-term nature (SDNN or RMSSD), or in the frequency domain e.g. low frequency (LF) or high frequency (HF). Time domain HRV is known to decrease during stress or mental exertion and depression; conversely when elevated it has been associated with positive valence found in relaxation (Cacioppo et al., 2000). In the frequency domain, the LF component is considered to correlate with both parasympathetic and sympathetic nervous system (PNS and SNS) activity and the HF with PNS activity (Berntson et al., 1997). Another measure of the ANS is found in the electrodermal activity of the skin, i.e. skin conductance or galvanic skin response responding to increases or decreases in sweat correlating with changes in SNS activity.

To provide context to where neuroscience research and methods have been applied to address the needs of clinical populations (translational research), it is useful to highlight the primary areas of convergence between neuroscience and music therapy

Music Therapy and Neuroscience: Areas of Convergence

Music and Neuroplasticity

A core area of convergence in neuroscience, music therapy and music medicine literature, is in the examination of neuroplastic change, or neuroplasticity. This well-established model stems from early animal studies (e.g. Hebb, 1949; Lashly, 1929) that led to an explanation of the adaptation of neurons in the brain during learning processes. When neuroplasicity occurs, the brain reorganizes itself by creating new neural pathways. Here synapses, the structures allowing neurons to pass electrical signals to one another, are repeatedly and persistently stimulated due to repeated exposure to sensory (e.g. temporal, visual, physical, or ‘somatosensory’) stimuli in a process known as ‘Hebbian learning’. Musical activity may provide an ideal stimulus in this context, with the potential to literally change the shape and connectivity of brain structures, and so may be harnessed to provide clinical improvements in a wide range of clients with neurological disorders. This is evident most notably in motor rehabilitation, but also in work with speech, cognition, mood disorders, and disorders of consciousness.

Since the development of neuro-imaging technology in the 1980s, neuroscientists have been able to provide evidence of musically induced neuroplasticity. The repeated activity of practice and performance of music, activating as it does so many neuronal systems, offers neuroscientist the perfect area in which to study neuroplasticity, by focussing on anatomical and connectivity differences between musicians and non-musicians. For example, in one of several such studies reviewed by Münte, Altenmüller, & Jäncke (2002), Pantev et al. (1998) found functional reorganization extending across the sensory cortices in pianists and violinists, as a product of repeated use of brain areas activated by musical learning.

Putkinen and colleagues (2015) have shown musical training activity from preschool through to adolescence improves executive functions and control over auditory processing, even after accounting for pretraining group differences between trained and untrained subjects. The same group of researchers discovered highly specialized cortical reactivity for musicians who are trained differently to specialise in different genres. The automatic brain responses to deviants (i.e. oddball sounds, pitches, or rhythms embedded in musical recordings) in MMR recordings were selectively enhanced for tuning in classical musicians, timing in classical and jazz musicians, transposition in jazz musicians, and melody contour in jazz and rock musicians (Tervaniemi, Janhunen, Kruck, Putkinen, & Huotilainen, 2015). This specialisation highlights the diversity of neuro-plastic change affected by different musical activities.

A model to explain how musical activity and associated neuroplasticity might benefit the neural encoding of speech has been proposed by Patel (2011). In essence, his ‘Opera Hypothesis’ details how musical experiences drive adaptive plasticity in speech-processing networks when meeting five conditions (a) overlap: in the brain networks processing music and speech acoustic features; (b) precision: when music drives more activity in the precision of processing within these shared networks than speech; (c) emotion: where musical activities elicit strong positive emotion within the networks; (d) repetition: where the musical activities are frequently repeated; and (e) attention: the musical activities are related to focused attention. Trost et al. (2014) provided further support for this model, observing that the more pleasant we find music, the greater extent to which areas of the brain involved in attention and emotion processing become entrained to the rhythm of the music.

A natural development of the above research has been the establishment of a branch of music therapy known as Neurologic Music Therapy (NMT). NMT comprises 20 techniques developed or incorporated from elsewhere to support motor, speech and cognitive rehabilitation in acquired brain injury and neurodegenerative populations (Thaut & Hoemberg, 2014). Examples of efficacy studies of NMT techniques using neuroscience methods are provided in the following section.

Music and Emotion

An established view amongst neuroscientists is that the emotional power of music stems from the way it activates dynamic aspects of neural systems usually implicated in the production of emotions such as joy and sadness. The emotional effects stem from how these systems are both independent of, and highly involved with cognitive processes (Blood Zatorre, Bermudez, & Evans 1999; Panksepp & Bernatzky, 2002). A developing understanding of emotional responses to music at a neural level are afforded through fMRI methods, which have identified activity in the primary limbic and paralimbic structures, in brain regions known to be involved across the ‘initiation, generation, maintenance, termination, and modulation of emotions’ (Koelsch, 2009, p. 374). Koelsch believes this understanding of how music affects these areas should eventually translate into music therapy treatments addressing dysfunction in these areas, as found in depression, anxiety, and post-traumatic stress disorder (PTSD).

Sena Moore’s (2013) systematic review of the neural effects of music on emotional regulation highlights the emerging connections in studies of music processing, attachment, stress management, and emotion regulation, illustrating the great potential for neuroscientific examination of music therapy interventions in this field. Maladaptive emotion regulation development is implicated in a range of childhood pathologies (Röll, Koglin, & Petermann, 2012; Zeman, Cassano, Perry-Parrish, & Stegall, 2006) and is recognised as a risk factor for future mental health problems (Röll et al., 2012; Hunter, Minnis, & Wilson, 2011). Neuroscience has developed our understanding of emotion regulation as characterized by increased activity in the brain regions and structures of the anterior cingulate cortex, orbitofrontal cortex, and lateral prefrontal cortex implicated in cognitive control, accompanied by decreased activity in in the area known as the amygdala (e.g. Gyurak et al., 2011; McRae et al., 2010; Rempel-Clower, 2007). As noted, there is wealth of music neuroscience studies illuminating corresponding neural activation by musically evoked emotions (e.g Blood & Zatorre, 2001; Koelsch, 2010; Salimpoor, 2011). However research is generally limited to fMRI investigations of listening to pre-recorded music; translational, practice-based studies using established, interactive music therapy methods, are needed to explore this field more comprehensively (Sena Moore, 2013; Sena Moore & Hanson-Abromeit, 2015). One technique meriting such evaluation is Musical Contour Regulation Facilitation (MCRF) (Sena Moore & Hanson-Abromeit, 2015) designed to support emotion regulation development practice in pre-schoolers. The MCRF structures the shape and timing of a session to replicate the dynamics of the caregiver–child interaction through high arousal and low arousal music experiences. A study into the efficacy of MCRF is currently in development (Sena Moore, personal communication, March 3, 2016).

A range of studies in mental health has used distinctive electroencephalogram (EEG) responses to correspond to depression, avoidance behaviours and anxiety. These focus on (a) frontal alpha asymmetry (FAA), where higher left sided activity in alpha is associated with active inhibition relating to depressive behaviours (Cooper, Croft, Dominey, Burgess, & Gruzelier, 2003; Thibodeau, Orgensen, & Kim, 2003), and frontal midline theta (FMT), correlated in a range of studies with anxiety (e.g. Suetsugi et al., 2000). However, whilst this model has begun to be used in music therapy studies (see following section, Fachner, Gold, & Erkkilä, 2013; O’Kelly et al., 2013), the validity of both FAA and FMT has been called into question (Gold, Fachner, & Erkkilä 2013), suggesting caution against any over-reliance on these measures as reliable biomarkers of mental states.

Music and Cognition

Music perception alone involves a host of cognitive processes including encoding, storage, and decoding of information and events relating to musical experiences; musical performance extends these processes to reading, motor planning, decision making and so on. The neuroscience and music therapy literature in this area lags behind the literature relating to motor, speech and emotion domains in terms of volume, however from a theoretical perspective, informed by studies with healthy subjects, there are some promising developments. For example Koelsch (2009) highlights how simply listening to music involves what describes as Action-Perception-Mediation where perception systems overlap those dedicated to action, through activity in the mirror neuron system (Rizzolatti & Craighero, 2004). Koelsch suggests this may be important for music therapy because the process underlies learning, understanding and the prediction of actions of others. Other important findings for music therapy include studies indicating early musical training can have a positive effect on auditory and cognitive functioning in adolescence (Putkinen et al., 2015) and late-life (Gooding, Abner, Jicha, Kryscio, & Schmitt 2013; Hanna–Pladdy & Gajewski, 2012).

Music and Relationship

Music is arguably the most social of all art-forms; the many and diverse examples of social musical activity are too numerous to list. Furthermore, with the exception of purely music listening (receptive) methods, or music medicine approaches where recorded music might be prescribed, music therapy is a live, dynamic process involving two or more participants jointly improvising, singing, or creating compositions together. Whilst traditional neuroscience may have viewed the nervous system in a vacuum devoid of social influence, the comparatively recent development of social neuroscience explores the neuro-biological structures and mechanisms implicated in social processes and behaviour (for an overview see Cacioppo & Berntson, 2009). Fachner (2014) encourages music therapy researchers to explore this approach, so that we may understand how “time processes of musical communication and physiological change creates frameworks for researching such processes” (p.793). Although research with clinical populations is lacking, studies to date have shown the utility of providing biomedical data from electrocardiogram (ECG) recording of musicians improvising together (Neugebauer & Aldridge, 1998). Elsewhere studies incorporating EEG recordings of ensemble (Babiloni et al., 2011) and duet performance (Sänger, Müller, & Lindenberger 2012), have highlighted the coherent and synchronous behaviour of heart rate, frontal and central brain regions as musicians perform together. Furthermore, an fMRI study by Abrams et al. (2013) found when individuals listen to extended pieces of classical music together, synchronous brain responses occur in a host of brain regions and structures; the bilateral auditory midbrain and thalamus, primary auditory and auditory association cortex, right-lateralized structures in frontal and parietal cortex, and motor planning brain regions.

The methodological challenges to measuring synchronous brain responses in groups of musicians or music therapy participants in situ are significant. Whilst fMRI methods preclude both detailed temporal recordings and any activity involving significant movement or human interaction, EEG methods can be used, although unwanted movement artefacts also pose significant challenges to extracting accurate data from activities involving instrumental play or singing.

Studies using biomarkers relating to stress, immunity, or social affiliation offer a pragmatic solution to monitoring neurobiological measures involved in group dynamics in pre-post studies. For example Keeler et al. (2015) monitored changes in plasma oxytocin and adrenocorticotropic hormone (ACTH) as measures of social affiliation, engagement, and arousal in group singing (improvised and pre-composed), with concurrent self-scoring on flow state to measure participants absorption in the tasks. Findings indicated group singing reduced stress and arousal on ACTH measures, with concurrent increases in social flow.

Music Therapy Research Using Neuroscience Methods

To summarise the range of papers featuring collaborations between music therapists, neuroscientists, and other professionals, it is useful to separate the studies by the fields of practice in which this research has been conducted. This summary will focus primarily on studies incorporating clinical input from music therapists; however where important transferable lessons are offered, music medicine studies involving other health professionals investigating music interventions with neuroscience methods will be included. An important caveat to note here is that music medicine studies do not typically involve aspects of relationship development or human musical dialogue core to mainstream music therapy practice (Magee & Stewart, 2015). Nonetheless, the understanding of music induced plasticity and the perception and cognition of music at a neural level afforded by such studies are invaluable to therapists seeking to explore and evidence their work from these perspectives. This section will focus on areas of most research activity within larger areas of clinical practice, but is by no means exhaustive of all published music therapy/neuroscience research collaborations or clinical populations investigated.

Motor Rehabilitation

As detailed previously, NMT techniques are now well evidenced for treating those with motor disabilities from stroke (Thaut, McIntosh, & Rice, 1997) and Parkinson’s disease (Thaut et al., 1996), leading to support for one particular technique to improve gate, Rhythmic Auditory Stimulation (RAS) in the most recent Cochrane Review of Music Therapy with Acquired Brain Injury (Bradt, Magee, Dileo, Wheeler, & McGilloway, 2010). Behavioral, physiological, and movement analysis indicate entrainment cues from music can modulate the timing of movement, improving spatial and force parameters (Thaut, McIntosh, & Hoemberg, 2014), as illustrated by Bukowska et al.’s (2015) study of NMT techniques to support mobility and stability with Parkinson’s disease. Unfortunately, the very nature of motor rehabilitation presents a major challenge for neuro-imaging methods, which mostly require stillness to avoid movement artifacts. Nonetheless, study of smaller movements such as wrist flexion is possible. For example, Schaefer and colleagues (2014) were able to use MRI methods to reveal cueing movement with actual or imagined music engages the motor network regions needed for wrist movement more than self-paced cuing without music. Given the compelling evidence of NMT techniques improving motor function in clinical populations, the field merits further research, exploring pre-post changes in neural structures related to such improvements.

Affective Disorders

As detailed previously, the evolving understanding of neuroscientific mechanisms involved in the emotional effects of music provide compelling evidence from healthy populations to inform music therapy practice. However, neuro-imaging studies with clinical populations are scarce, with the exception of Fachner et al. (2013) who used EEG to measure changes in brain activity of 79 subjects with depression receiving psychodynamic improvisational music therapy. Focussing on FAA and FMT before and after 3 months of therapy, they discovered lasting changes including significant increases at left fronto-temporal brain regions for alpha and theta frequencies and pre-post increased FMT correlating with depression and anxiety, as measured on Hamilton Anxiety and Depression scales. The authors concluded that the verbal reflection and improvisation focussed on emotions supported neural reorganization in these areas, underpinning the clinical improvements observed. A study with older adults with depression using neurofeedback methods to alter the dynamics of their preferred music also produced significant changes in EEG measures (a decrease of relative alpha activity in their left frontal lobe) correlating with decreased depression (average improvement of 17.2% in Beck Depression Inventory scores). Interestingly, the alpha bandwidth changes in this study accord with the expected changes accompanying improved mood, whilst the frontal alpha changes in the Fachner et al. study contradict the expected relationship with mood. This may suggest distinct mechanisms are involved in music therapy incorporating verbal reflection compared to more receptive techniques, however, as noted, caution is required regarding the validity of FAA and FMT (Gold et al., 2013).

Stroke

The global burden of stroke is high and is likely to increase into the future decades with demographic trends in populations (Feigin, Lawes, Bennett, & Anderson, 2003), with complex and diverse disability outcomes including medical complications, cognitive impairment, pain, communication disorders (aphasia), gait ,and other mobility impairments (Kumar, Selim, & Caplan, 2010). Whilst studies incorporating music therapy and neuroscience methods are lacking, Särkämö et al. (2008; 2014) have conducted a series of investigations comparing the effects of daily preferred music listening (MG) to audio book listening (ABG) or standard care controls (CG) for individuals with acute middle cerebral artery stroke at 3 and 6 month follow up periods. Initial investigations from the randomized controlled study employed a battery of behavioural and psychological tests indicating music listening to be superior in improving cognitive recovery and mood (Särkämö et al., 2008). Further structural MRI investigations comparing the MG, (n = 16), ABG (n = 18) and CG (n = 15) suggested evidence for a process of cognitization (Forsblom, Laitinen, Särkämö, & Tervaniemi, 2009) whereby anatomical changes in brain regions associated with verbal memory, language skills and attention (e.g. the left and right superior frontal gyrus) correlated with actual improvements in these areas at 3 and 6 month follow up periods for the MG listening compared to ABG and CG cohorts.

As noted, aphasia, or the partial or total loss of the ability to communicate verbally, is a significant consequence of stroke, affecting an estimated 38% of stroke survivors according to a review of 881 acute stroke patients (Pedersen, Stig Jørgensen, Nakayama, Raaschou, & Olsen,1995). Speech and music therapists have adopted the long established technique of Melodic Intonation Therapy (Albert, Sparks, & Helm, 1973) to address stroke related aphasia. Whilst the OPERA hypothesis (Patel, 2011) goes some way to indicating why the technique might work from a neuroscience perspective, Schlaug and colleagues using both fMRi (2008) and DTI methods (2009) have more closely examined the technique. The authors found the distinctive melodic intonation and left hand tapping of the technique to correlate with priming of sensorimotor and premotor cortices for articulation, with concurrent neuroplasticity in a brain structure important for connecting brain regions dedicated to auditory processing and motor activity required for speech (the arcuate fasciculus). Furthermore, another melodic or rhythmic-based treatment for aphasia (‘SiPARI’) developed by music therapist Jungblat and colleagues (2014), has recently been examined with fMRI. Whilst caution is required given the case series nature of the study (n = 3), data indicated new activity in areas adjoining injured brain regions in the left superior temporal gyrus, which the authors concluded may account for improvements noted in the temporal sequencing of speech.

Dementia

In tandem with an ageing population, and successes in treating cancer and heart related conditions, dementia, compared other age related conditions, is likely to increase in prevalence; for example, between 2006–07 and 2010–11 the numbers affected by dementia in the UK rose by 25% (DH, 2012). Apathy, anxiety, cognitive problems (in memory, executive functioning and planning), aggressive behaviour, restlessness, and depression are just some of the symptoms affecting the individual with dementia’s quality of life, relationships, and cost of care (DH, 2012).

The area of musically supported cognitive rehabilitation is of particular interest to the growing field of dementia research. Using a battery of neuropsychogical tests, Särkämö and colleagues (2014b) found music-based interventions may be beneficial in maintaining cognitive as well as emotional, and social functioning. Furthermore Jacobsen et al. (2015) used fMRI methods to delineate an area of the brain dedicated to musical memory that survives the damage to the brain caused by Alzheimer’s disease. The authors found the two brain regions: the caudal anterior cingulate and ventral pre-supplementary motor area, were uniquely activated in the neural encoding of long-known music, compared to recently known and unknown recordings. This research for the first time underpins with objective scientific evidence a strong case for musical interventions that could enhance the well-being of those with dementia by engaging the healthy part of the brain, where strong connections between music and meaningful autobiographical moments, identity, and self-expression may lie.

Whilst music therapy neuroscience collaborations are lacking in this field, Hsu and Monkton (2014) have conducted a pilot study incorporating HRV analysis of music therapy/client pairings, where physiological data revealed modulation in emotional arousal during improvisatory music therapy. The authors believe this may enable identification of sensory cues during sessions, guiding the therapist to reduce symptoms such as anxiety. A further pilot study in sound stimulation with this population shows promising results. Music therapist Clements Cortes and colleagues (2016) were informed by neuroscience evidence suggesting older adults with Alzheimer’s might benefit from boosting the level of 40Hz sound in their environment to promote connectivity between the thalamus and the hippocampus brain regions. Using a specially designed acoustic chair with 18 participants, the researchers found stimulating the somatosensory system in this way produced significant improvements in mood and cognition on behavioural scales, which was supported by qualitative observations (Clements-Cortes, Ahonen, Evans, Freedman, & Bartel, 2016). Despite music therapist involvement, this study in rhythmic sensory stimulation is not examining standard music therapy practice; however the findings for future research are noteworthy, notwithstanding the pilot scale of the research.

Cancer and Palliative Care

Whilst advances in pharmacology and other approaches have been successful in addressing the physical pain associated with cancer and palliative conditions, psychosocial and affective symptoms remain a challenge to clinicians and researchers (Swash, Hulbert-Williams, & Bramwell, 2014; Soothill et al., 2001). Music therapy is well regarded as a holistic treatment appropriate for addressing the psychosocial and spiritual needs of those with cancer and palliative conditions and their carers (Running, Shreffler-Grant, & Andrews, 2008), however support in the literature for music therapy and palliative care is primarily non-biomedical and qualitative (e.g. O’Kelly & Koffman 2007).

In cancer care, two studies are noteworthy for their inclusion of neurophysiological measures. Lee and colleagues (Bhattacharya & Lee 2012; Lee, Bhattacharya, Sohn, & Verres, 2012) compared the EEG recordings of 20 patients using a monochord (MC) to 20 receiving progressive muscle relaxation (PMR) whilst receiving chemotherapy over 6 months. The data revealed significant improvement in all participants’ physical and psychological states and state anxiety concurrent with increases in posterior theta and a decrease of midfrontal beta-2 band (20—29.5 Hz) EEG activity during the end phase of relaxation treatment. The MC group was particularly notable for decreased alpha activity compared to PMR, and modulation of complexity of theta band at posterior regions (Lee & Bhattacharyab, 2012). The authors recommend that these novel EEG finding merit further investigation with larger samples to establish differential biomarkers of receptive music therapy compared to instruction based relaxation methods.

To explore the effects of improvisational music therapy with cancer patients from a neurochemical perspective, Burns and colleagues (2001) included salivary immunoglobulin (relating to immunity level), and cortisol (relating to stress) concurrently with psychological assessment and focus group data in a pilot study, finding support across measures for increased wellbeing, and decreased stress and tension in the 29 participants.

Disorders of Consciousness

Disorders of consciousness (DOC) comprise a continuum of acquired conditions with two primary diagnostic categories: vegetative state (VS), where there are no discernible indications of consciousness despite evidence of wakefulness (American Congress of Rehabilitation Medicine, 1995), and minimally conscious state (MCS), a condition which may follow VS where consciousness is limited (Giacino et al., 2002). The rationale for using music therapy to support assessment and rehabilitation is clear when one considers music as a non-verbal medium capable of supporting arousal, without dependence on verbal processing (Magee & O’Kelly 2015; O’Kelly & Magee 2013a). There has recently been a range of research collaborations between neuroscientists and music therapists using EEG and HRV measures (O’Kelly et al., 2013), PET (Steinhoff et al., 2015; Vogl, Heine, Steinhoff, Weiss, & Tucek, 2015), and music medicine studies using fMRI (Heine et al., 2015; Okumura, 2014; Verger et al., 2014) and HRV (Riganello, Arcuri, Quintieri, & Dolce, 2015; Riganello, Candelieri, Conforti, & Dolce, 2010), together with a Frontiers special research topic (Magee, Tillman, Perrin, & Scnackers, 2016) including a range of review papers featuring input from music therapists. In summary these papers are underscoring behavioural studies of assessment (e.g., Magee, Siegert, Daveson, Lenton-Smith, & Taylor, 2013; O’Kelly & Magee, 2013b), and rehabilitation (Formisano, 2001), by exploring the effectiveness of music therapy based on its ability of music to act both on the external and internal neural networks supporting consciousness (Perrin, Tillmann, & Luauté 2015; Vanhaudenhuyse, 2011), supporting arousal, therefore optimising conditions for assessment of awareness (O’Kelly et al. 2013), and activity in the auditory cortex and brain regions dedicated to autobiographical memory (Heine et al., 2015), indicating cerebral plasticity may be enhanced in autobiographical (emotional and familiar) contexts provided by preferred music for MCS patients (Verger et al., 2014). This final potential is currently being explored using neurophysiological and behavioural measures (Rappich, James, Ramaswamy, Lord, & O’Kelly, unpublished).

Autism Spectrum Disorders (ASD)

As with dementia, and other conditions where combined issues of capacity and vulnerability need careful consideration, the use of more invasive neuroscience methods such as fMRI on participants with ASD pose considerable challenges to conducting research. Nonetheless, a wealth of non-neuroscience research points to the effectiveness of music therapy in a range of important areas. The most recent Cochrane review of music therapy of children with ASD selected 10 high quality behavioural studies, whose combined results led the authors to conclude that music therapy can improve “skills in primary outcome areas that constitute the core of the condition including social interaction, verbal communication, initiating behaviour, and social-emotional reciprocity…” and ‘”help to enhance non-verbal communication skills within the therapy context” (Geretsegger, Elefant, Mössler, & Gold, 2014, p.2). Research with participants with high functioning ASD involving receptive musical interventions is more amenable to neuroscience methods, as Gebauer and colleagues (2014) illustrated in their recent study of musical emotion processing using fMRI methods. The authors found participants with ASD showed increased cognitive processing and physiological arousal in response to emotional musical stimuli of a happy nature compared to neurotypical ASD controls. This finding may guide music therapists, by providing neurological evidence of the need to be mindful of the increased cognitive load experienced by clients with ASD, when they are decoding the emotional content of music.

Challenges and Limits to Music Therapy and Neuroscience Collaborations

In my early music therapy career in palliative care, I first became enthused with music neuroscience when attempting to understand the profound effect of one session with a client who became aphasic following removal of a brain tumour. In one session, with a simple piano accompaniment from me, the client found the ability to sing his favourite football teams’ anthem, despite his inability to communicate verbally. This marked the beginning of a process where regular music and speech therapy gradually enabled a full return of functional speech. Whilst this experience drove me on to find scientific explanations for the work (e.g. Patel, 2011; Schlaug et al. 2008), it made me mindful of the limits of neuroscience for providing the full picture in this case. For example, would this effect have happened without the therapeutic relationship I had developed prior to the landmark session, and how could this be captured with neuroscience methods? Was it just repetition and neuroplasticity that supported his recovery, or was the instillation of hope brought from the event equally important? And how could neuroscience capture the ripple effect of working with him later on in the more social environment of the day hospice lounge, where other staff and patients described being inspired by his transformation?

This example highlights the limits of neuroscience methodology in explaining music therapy, let alone evidencing its entire multi-dimensional sphere of action. As Ansdell (2014) pointed out, in researching the effectiveness of music therapy we should acknowledge:

interactive musicking people in real-life situations, where they are doing things that matter with music, and doing things through music. This is all to put music back into its rightful place in social life – back into its material, social and cultural ecology.( p.821)

Whilst researching the social, spiritual, and cultural components of music therapy is mostly beyond the scope of current neuroscience methods, the evolving neuroscience understanding of the emotional effects of music holds more promise. However, isolating what aspect of music causes an emotional effect is fraught with methodological challenges. For example, to what extent are we moved emotionally in a therapy situation by intrinsically musical elements (e.g. rhythm and melody); how we move and physically embody aspects of a musical performance in improvisation, or the personal memories, associations or cultural relevance of a performance or recording? The neuroscience in this field is dominated by fMRI studies that require subjects lay still in a noisy scanner, which can only represent brain activity in laboratory settings at well-spaced intervals, devoid of social and relational elements core to music therapy practice. Frequently, the musical stimuli used are sequences of synthesised tones or short excerpts of music, chosen with prior assumptions by researchers regarding emotional content. Furthermore any method of recording affecting an individual’s comfort levels, or how natural a setting is, may poorly reflect real life music therapy, or the ecological validity of findings.

Finally, mainstream neuroscience methods tend towards standardisation and replicability, inappropriate to studying music therapy approaches predicated on personalising and tailoring the personal and musical qualities of an intervention to each client (Magee & Stewart, 2015). Thus, whilst areas of clinical work directed to specific functional goals such as speech or mobility rehabilitation may be amenable to a standardised protocol, capturing what works with neuroscience in improvisatory, creative, humanist or psychodynamic oriented work is less so. Nonetheless the examples provided in this paper (Fachner et al. 2013; O’Kelly et al. 2013) illustrate the utility of neuroscience methods in empirical comparisons, particularly when used conjointly with behavioural and clinical measures.

Music Therapy and Neuroscience: The Way Forward

This paper appraises the diverse range of evolving research activity exploring music therapy from a neuroscience perspective. Whilst the more nebulous, interpersonal aspects of music therapy may always evade measurement from EEG, fMRI etc., technological advances in neuroscience methods promise future opportunities for meaningful research, particularly for in situ studies exploring the music therapy process. For example, increasingly accessible portable and wireless EEG technology might allow for a more naturalistic data capture of neural activity. Furthermore HRV is an underused yet practical and non-invasive method to underpin behavioural assessment with new insights of neural activity relating to physiological, cognitive and emotional aspects of practice.

The use of neuroscience methods should be used concurrently with clinical markers of progress, and research methods which serve the qualitative, experiential, and relational aspects of music therapy, to avoid any tendency towards reductive explanations of clinical work. On the contrary, music therapy and neuroscience collaborations are capable of exploring some of the less understood parts for which music therapy is greater than the sum of, and in doing so offer up a more holistic understanding of practice, and a broader evidence base for this field.

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