The Marriage of Neuroscience and Music Education: A Systematic Review of Literature

Research Methodology

This study aimed to articulate the most salient themes emerging in the literature regarding educational and neuroscientific perspectives on music, learning, and the brain, affording particular attention to the role of information transfer with respect to music. Through the provision of an exhaustive summary and consequent synthesis of the relevant and recent literature, this study aimed to bridge gaps between educational and neuroscientific evidence, articulate strengths and weaknesses in the body of literature, and derive conclusions from numerous and varied sources that meet specific criteria. Ultimately, this study's conclusions will facilitate future directions of research regarding the marriage of neuroscience and music education, providing key and practical mechanisms for integrating the existing research into music teaching practice.

Systematic Review of Literature Method

Types of literature reviews diverge significantly from one another, with narrative, systematic, and meta-analytic reviews being the three most common types. Narrative reviews represent the most traditional type of literature review methodology, appraising and synthesizing the relevant literature and usually providing a foundational ground for primary research. Generally framed as less valid and more biased than systematic or meta-analytic reviews, narrative reviews identify broad and qualitative criteria for the literature used in the analyses. Alternatively, systematic literature reviews are more practice-based, best-evidence syntheses that provide a thorough and unbiased review of the existing literature. Rhoades highlights that "with the onset of the 21st century, systematic reviews have become increasingly more common, replacing narrative reviews and expert opinions or commentaries. ...[S]ystematic reviews can be stand-alone research papers published in peer-review journals and their importance cannot be overemphasized" (p. 359). Systematic literature reviews integrate findings across multiple studies which pertain to a specific research question or topic, remaining critical and objective throughout the research process.

A central weakness of systematic review methodology is publication bias, or the tendency of publications to be resistant to the inclusion of null or negative research findings (Katapodi and Northouse, 2011; Rhoades, 2011). In order to minimize this potential, systematic reviews are necessarily broad in their timeframes for publication as well as the types of publications sourced. This study will overcome this common weakness of systematic review methodology by referencing a wide range of literature, all of which is scholarly in nature with the type of publication varying considerably across multiple disciplines. The nature of the study, examining the dual fields of education and neuroscience, also provided a channel for overcoming publication bias which tends to be field-specific.

Additional weaknesses of systematic literature reviews include the overlooking of biases inherent to the reviewed studies and poorly critiqued studies. Ideally, literature reviews expose rather than further literature bias, and this is accomplished readily by remaining objective throughout the research process, particularly when selecting studies for inclusion. Errors in systematic literature have been identified as linked to the failure to examine multiple perspectives, with the researcher beginning the process from a narrow position through which bias becomes inevitable. This study overcame these two common weaknesses by examining multiple perspectives during the review and identifying biases inherent to the literature.

Unlike meta-analytic reviews which provide statistical analyses of the data garnered from the systematic review (Rosenthal and Dimatteo, 2001), systematic reviews, alone, embody a qualitative component which is critical to this present study. The primary themes in the literature, while critically and objectively reviewed during the analysis, were qualitatively synthesized in order to articulate possible ways to bridge research-practice gaps, identify biases and other weaknesses inherent to the literature, and acknowledge future directions in research that may further validate the marriage of neuroscience and music education. Systematic review allows for the researcher to explore a broad range of literature whilst remaining objective and without eliminating the ability to explore possible underlying meanings in the existing studies.

Research Questions and Inclusion Criteria

The specific objectives of this study were as follows: To identify the dominant themes in neuroscientific and educational literature; to highlight existing weaknesses and gaps in the literature; to provide an applicable foundation for embedding neuroscience-guided practice into music education. By extension, the following research questions are proposed:

• Research Question 1: What are the dominant themes in brain-based education literature?
• Research Question 2: What are the dominant themes in neuroscientific literature regarding music's effect on the brain, broadly, and learning, specifically?
• Research Question 3: In synthesizing the literature's dominant themes, how can neuroscientific conclusions be engrained into music teaching practice?

Only scholarly, peer-reviewed literature was included in the study, and all literature published prior to 1998 was excluded. The timeframe and types of publications included in the review are necessarily broad in order to eliminate publication bias. The keywords and phrases searched from several databases were as follows: "music + brain + education," "music + learning + brain + development," "music + learning + transfer," and "music + education + brain + development." After excluding studies from non-peer-reviewed journals or publications and those published before the year 1998, thirty-five studies were included in the review, with peer-reviewed publications ranging widely from The American Journal of Psychotherapy to Music Therapy Perspectives Journal. The following section provides a systematic review of these studies, affording particular and critical attention to the research questions.

Review of Literature

Recent neuroscientific literature focuses on the nature of cognition as affected by music, affording particular attention to brain plasticity and the multiple areas of the brain impacted by performing or listening to music. Brain-based education literature has highlighted the range of ways in which creative experiences with music and other arts enhances the transfer of knowledge from one domain to the another (Dietrich, 2004). Significant criticism has targeted brain-based education literature (Corrie, 2000), however, fostering the emergent need to examine neuroscientific and education-based research in parallel with one another.

The Cognitive Niche, Working Memory, and Brain-Based Education

Brain-based education has emerged as a common basis for educational practice, reform, and interventions (Sternberg, 2008). Substantial criticism surrounds the unquestioned application of brain-based educational practice, however, with common arguments highlighting the failure of science to concretely validate the application of neurological research in the educational realm. Both fervent supporters and adamant skeptics of brain-based education highlight empirical evidence for their perspectives, rendering reform efforts largely at a stand-still in multiple nations. Sternberg (2008) asserts that "the question is not whether educators can take brain-based or other biological research and derive educational implications from it. The right question is whether they can take such research and derive unequivocal educational implications. If not, then we have metaphor, but we do not really have science" (p. 420). The author continues by highlighting several instances in which neuroscience does not validate educational interventions, particularly targeting the notion of brain size and development with respect to learning, concluding that brain-based education should be viewed as a perspective on education rather than an actual, scientifically valid mechanism for reform.

Conversely, Patterson and Perlstein (2011) argue that brain-based education, particularly that which encourages the use of creative exercises for stimulating brain growth, is firmly grounded in science. The human brain, the authors posit, thrives on creative challenges which foster the repair and rejuvenation of brain structures. Artistic activities that engage the mind, evoke emotions, encourage problem-solving, and stimulate multiple senses encourage the adaptive mode of the brain, or the so-called cognitive niche, which allows human beings to adjust quickly to their environments. Key elements for creative application of brain-based education are play, improvisation, and invention, with the young and developing brain particularly reliant upon these three variables.

The human brain is unique in that it does not reach a point at which brain development ends. Unlike the brains of other animals, those of humans remain in a state of neotany, or extended learning throughout most of their lives. The cognitive niche has rendered creative exploration necessary, fostered in part by the constantly shifting nature of modern civilization. Patterson and Perlstein (2011) contend that human beings must necessarily be a state of constant learning and adaptation, with experiences with the arts enhancing and cultivating that state.

Several studies suggest that creative experiences drive brain size expansion, with the computational prowess of the brain boosted by the broadening of network connections fostered by brain cell growth. Primate brains must exercise the creative capacity of the brain in order to strengthen these connections, however, with human beings' cognitive growth dependent entirely upon creative stimulation. Patterson and Perlstein (2011) assert that the human brain's executive functions, including working memory, expanded in parallel with the growth of culture fifty millennia ago, at which time the arts, religion, symbolism, and personal adornments became commonplace. Working memory enables human beings to maintain multiple ideals and concepts within the conscious mind for a period long enough to manipulate and synthesize them. In parallel with the expansion of working memory and exponential cultural growth, the prefrontal cortex grew considerably approximately 50,000 years ago, distinguishing humans from other primates.

A region of the human brain known as Area 10 embodies several unique traits, not the least exceptional of which are clusters of nerve cells very densely organized and extremely connected to other brain areas. White matter connects the brain to the rest of the nervous system, facilitating high degrees of interconnectivity between the brain and the rest of the body, also allowing for enhanced cognitive flexibility and ease in learning. The creative process is multi-phased, including initiation, saturation, manipulation, incubation, inspiration, implementation, and evaluation, with all phases facilitated by Area 10 and the pervasive nature of white matter in the brain (Zeki, 1998).

Brain-based education advocates highlight creativity, the arts, and music specifically as integral to brain growth and development (Strickland, 2001). The creative process involves multiple brain areas and a range of cognitive skills, with emotion playing a key role. Combined efforts of the right and left hemisphere parallel both the rational and emotional processes of the brain's functioning when the individual is engaged in a creative activity, with domain specific skills honed in accordance with the type of activity being pursued.

The ability of the brain to adapt and change in response to certain stimuli is integral to brain-based education, with researchers asserting that environmental factors influence the brain as much as hereditary forces (Wilmes et al. 2008: 670). Specifically, Wilmes et al. (2008) contends that thirty to sixty percent of the neural wiring is formed in response to hereditary, while forty to seventy percent is resultant from environmental forces. Reducing stress and using sensory-based instruction in order to facilitate optimal learning is central to brain-based learning, with music influencing the brain by either enhancing or diminishing the actions of attentional neurotransmitters.

Brain-based education has been criticized for its lack of empirical ground primarily due to the emerging nature of the field (A Challenge, 1999; Davis, 2000). Many studies in the realm of neuroscience are exploratory in nature, and brain-based education warrants severe caution be taken in translating brain-based research into the classroom (Brandt, 1999; Bruer, 1999). A dominant theme on which a wide spectrum of brain-based studies agree, however, is that brain development during childhood represents a key window of opportunity to which musical influence is integral.

Brain Development and Musical Influence during Childhood

Neuroscience has expanded considerably in conjunction with technological innovations such as positron emission tomography (PET) and electroencephalograms (EEGs), with the impact of music on the brain becoming of particular interest to researchers due to apparently multiple and diverse brain effects related to music (Strickland, 2001). During certain critical periods of childhood, the brain undergoes extreme synaptic growth in the visual, auditory, and prefrontal cortexes. By six months of age, all three cortexes have undergone rapid synaptic growth and those not used following this time will be slowly lost from infancy through adolescence (Strickland, 2001). Consequently, brain development during childhood is particularly critical, as brain capacity can be reduced through synaptic loss.

Synaptic growth is integral to learning, as it prepares the individual for learning from environmental experiences (Cohen, 2002). Additionally, synaptic growth results from environmental experiences, suggesting a bidirectional relationship between brain development and the individual's environment during childhood. Strickland (2001) posits that the brain's synaptic growth is fostered by both direct and indirect environmental influences, with the former being specific learning tasks which effectively generate new synapses and the latter being a change in the individual's emotional state. When a stimulus can be provided that both directly and indirectly influences the brain, synaptic growth is optimized.

Though the most sensitive period of brain growth occurs during very early childhood, with the greatest brain receptivity and sensitivity to stimuli in the external environment occurring during infancy, critical periods of brain development continue throughout childhood until adolescence. Taly-Ongan (2000) posits that brain plasticity, by which the brain is more changeable and adept at healing, is particularly inherent to the child's brain. Brain injuries that occur during early and middle childhood, specifically, are far less detrimental than those occurring after adolescence. While an adult suffering from a stroke in the left hemisphere of the brain would likely incur irrevocable loss of speech and language functioning, children with far more severe brain damage in the same area can develop nearly normal language abilities (Taly-Ongan, 2000). The speech and language centers of the brain become substantially solidified during puberty, reflecting reduced, though not nonexistent, brain plasticity.

Hemispheric dominance has been asserted to be responsible for the bulk of learning style differentiation, with the two cortical spheres having specialised functions affecting predisposal toward certain, cognitive capabilities. In the adult brain, the left hemisphere processes lingual information, addresses logical and mathematical functions, and recognises patterns while processing sequential material (Taly-Ongan, 2000).

The alternative, right hemisphere of the brain analyses spatial cues and operates more holistically, overall, being particularly sensitive to musical cues. Taly-Ongan (2000) asserts that the young brain is unique because both hemispheres cooperate to aid the child in making sense of his/her world. Cooperation between the left and right hemispheres results in a different type of cognitive processing that is more efficient than the type of cognition which occurs in a single hemisphere. When a stimulus is presented to the developing brain that would significantly impact a single hemisphere, such as music's impact on the right, cortical sphere, the processing ability of the other hemisphere may be simultaneously enhanced. Talay-Ongan (2000) highlights that music is one of the most critical stimuli that causes the left and right hemispheres to work in tandem, thereby enhancing cognitive processing abilities during childhood.

Music provides a mechanism for both directly and indirectly affecting the individual, with multiple musical experiences impacting the brain by stimulating both hemispheres. When engaged in playing a musical instrument, cortical activity has shown an increase among certain individuals. Specifically, cortical activity is the most significant among musicians who learned to play instruments before age nine, with string players having the highest cortical representation rates. Active music learning through which the individual is highly and directly engaged in the activity has the most significant impact on the brain, with the impact most notable during childhood and through adolescence (Strickland, 2001).

Madrazo and Motz (2005) assert that learning should be framed as a biological process which supports survival. Learning is first and foremost the brain's response to the environment, with synapses and dendrite branching occurring as the brain processes new information. Intelligence, by extension, is a brain-body-environment structure, complexly shaped by both environment and heredity. One hundred billion nerve cells create approximately 1,000 trillion synaptic connection points that are constantly organised and reorganised; this changes the physical structure of the brain, with children's brains more responsive to the growth which occurs in response to the learning experience. Children seek out patterns as a means of processing information, with learners constructing patterns out of previously learning information in order to integrate new material.

Learning does not occur in a single area of the brain, and memory is assembled in multiple locations. Madrazo and Motz (2005) content that engaging students actively through multiple activities, ideally combining music, emotion, sensory learning, and several types of communication with traditional learning. Lecture-and-drill methods have little ground in neurological research, as the brain will go into cognitive overload if too much information is being presented narrowly, in a single format (Jensen, 2005). Opportunities to diversely explore new information support learning by preventing cognitive overload.

During childhood, the continued plasticity of the brain renders music particularly integral to forming neural connections (Johansson, 2002). In particular, the learning of complex, bimanual finger sequences and translation of symbols into motor sequences changes the brain structure. Johansson asserts that the anterior part of the corpus callosum part of the brain is larger in musicians who began training before age seven: "To what extent most children can acquire musical abilities during critical periods of brain development and maturation, and to what extent they require innate predisposition, is a topic of debate. It is likely that interaction between predisposition, environment, and training is important for music as it is in many other areas" (p. 49). More importantly, evidence suggests that musical experience may promote brain plasticity later in life.

Both performing and listening to music fosters changes in brain anatomy and neural activity, with neuroimaging demonstrating that music affects multiple areas of the brain simultaneously (Johansson, 2002). Specifically, PET and MRI scans have shown that both the left and right hemispheres of the brain as well as the cerebellum are active when the individual is engaged with a musical activity. Cortical asymmetries evolved in the human brain in order to optimise processing of auditory information, with infants born with a neural capacity for music processing before they develop a similar capacity for language. Tillman (2009) argues that the connection between music learning and language development is a formidable one, with both cognitive and neural correlates similar to music and language; while the two systems have unique structures in the brain, the manner in which the brain processes sound is common to music and spoken language, with a mutually beneficial relationship in learning both simultaneously.

Both language and music integrate temporal-specific sequences of sound and rhythmic structures to be cognitively unfolded and processed by the brain. Additionally, both language and music are systems with limited elements and firm rules which guide understanding. Fedorenko et al. (2009) used neural imaging to explore the relationship between linguistic and musical, structural integrations, using sixty participants listening to sung sentences; the authors concluded that there is no competition for resources when the brain processes language and music structures. The study provides evidence that a core connection exists in the brain between music and language, grounding brain-based educators' assertions that music can facilitate language-learning in children. The cognitive linkages between music and other domains are not limited to linguistics, however, as treatments of brain-disorders have addressed music's ability to enhance control over non-verbal, spatial tasks. Much of the treatment-based research has posited that the healing of neural and behavioural issues is facilitated by the manner in which music engages multiple brain areas.

Transfer, Learning, Emotions, and Music: Critical Connections

Theorists have suggested that music learning yields positive impacts across subject areas, with the transfer of music skills to language and mathematics learning apparent among elementary and middle school students (Burton, Horowitz, and Abeles 2000: 228; Strickland, 2001). Strickland (2001) posits that rhythmic ability is directly bound to reading ability, in particular, and empirical demonstrates that even when reading instruction was temporarily replaced with music instruction, reading scores improved among eight year-old students. Burton, Horowitz, and Abeles (2000) are skeptical, however, that neuroscience offers any ground for transfer, citing that no scientific evidence exists demonstrating neurological functions of learning transfer from music, or any other arts discipline, to alternative subject areas in a causal function: "[T]ransfer, if and where it exists, may be part of a larger constellation of impacts of arts learning on other subjects," with the connection between the arts and learning in other disciplines not necessary causal but nevertheless evident. Specifically, the authors acknowledge a range of studies similar to that outlined by Strickland (2001) which posit that, despite a dearth of neurological evidence to ground the research conclusions, a clear, empirical link exists between creative experiences and gains in reading and mathematics. The improvements, Burton, Horowitz, and Abeles (2000) assert, are attributable to music's ability to boost cognitive capacity, allowing students to think more critically and representationally following a musical experience.

Emotional or mood-based responses to music in both therapeutic and educational settings have reflected the ability to enhance cognitive connections. Specifically, empirical evidence suggests that the emotion expressed by the music is the same emotion experienced by the listener. Schubert (2007) examined the relationship between musical emotion and felt emotion, concluding that his "study has demonstrated that the relationship between expressed and felt emotion does follows a general rule that-in the experimental laboratory setting at least-the magnitude of emotion perceived to be expressed in music is greater than or equal to the magnitude of the emotion felt by the listener" (p. 345).

Gardiner (2000) describes a process of mental stretching through which music education can facilitate learning transfer. The author cites that music's implications for learning manifest in values specific to music, the effects of music on other topics, and the influence of music instruction on other mental skills. According to Gardiner (2000), "the general idea of mental stretching has to do with changes in the representation and organization of a particular aspect of thinking that improves the way we think about distinctive kinds of information or specific kinds of mental tasks" (p. 2). The author asserts that music learning enhances not only the transfer of a specific type of knowledge to another academic domain; it creates opportunities for transferring attentiveness and other general skills. Gardiner (2000) warns, however, that most transfer literature implies that information moves from one area of the brain to another, but that skills are organised in the brain in a wide range of ways that can affect simple notions of transfer: "If, for example, two areas of skill change by changing their relationships to other areas of the brain, is this still transfer?" (p. 4) In conceptualising transfer differently, the term connotes a dynamic type of knowledge transfer through which information and skills may not necessarily move from one location to another but, in fact, change shape entirely during and following a musical experience.

The ability of musical experiences to enhance the transfer of specific skills that optimise learning appears less often in the literature than the notion that specific knowledge transfer can occur when students are exposed to music. Howard (2002) asserts that the goal of enhancing transfer capacity in the academic setting should not be to encourage cross-disciplinary transfer in the academic domain but skill-specific transfer from the academic to other environments. Gardiner (2000) argues that the prevalence of studies highlighting high-performing students' concurrent musical ability suggests that study skills and positive classroom behaviours are facilitated by music learning. Class participation, teacher-student cooperation, self-motivation, self-esteem, responsibility, and initiative have empirically reflected at significantly greater rates among high-achieving students. Moreover, these positive classroom effects are long-term rather than short in duration, with substantial contributions of music to learning.

Catterall (2001) asserts that the neurological basis for transfer is primarily relatively to the arts, alone, with evidence of transfer between math and reading, for example, weak at best. The author asserts that when an individual hears a single musical note for the first time, the auditory experience engages multiple regions of the brain related to emotion, memory, rational responses, and autonomous reactions. When the same note is heard again, the neural impulses travel in different patterns, albeit in the same multidimensional regions, than it did initially. The first experience with the musical note allows the brain to set-up a filing structure for the experience that provides a foundation for future experience transfer. Transfer then emerges over time rather than as a result of a single, musical experience.

Music and Education: Classroom Implications

Given the neurological basis for music's promotion of transfer and other manifestations of enhanced cognitive capabilities, research focusing on ways in which to integrate music meaningfully into the classroom has emerged recently as a topic of focus within educational discourse. Teacher perceptions regarding music education have been examined as a potential barrier to music integration. Kim and Choy (2008) assert that the self-efficacy of educators with respect to music, specifically the teacher's self-perceptions regarding his/her competence and outcome expectancy, either fosters or impedes music integration. Given the increasing elimination of music courses within national curricula, it is particularly necessary for primary school educators to feel confident enough in order to promote music learning.

Frederickson (2002) asserts that educators are charged to promote multiple ways of knowing about music in the classroom in order to garner the optimum, cognitive benefits from music learning. By extension, overcoming obstacles related to self-efficacy is central to supporting children's academic potential, with the primary school years being the most critical due to the plasticity of the young brain.

Gardiner (2000) cites that the ability of music education to impact other aspects of the curriculum is inextricably bound to the nature of the mental skills and knowledge representations presented during the musical experience. The likelihood of knowledge transfer is enhanced when the educators overlap music learning with that in other subject areas. The author asserts that learning in mathematics and language is particularly supported by transfers sourced from musical experience. Specific implications for classroom promotion of knowledge and skill transfer are bound to the focus on specific skill development. According to Gardiner (2000), optimal impacts from music learning occur when educators emphasis skill development over mere exposure: "Brain research of the last twenty years has developed an enormous amount of evidence suggesting that activity in the brain at work is very different from the brain at idle.... The value of doing to learning, not just observing, may perhaps have partly to do with the special qualities of brain involvement" (p. 20). Music listening has weaker and more short-lived neurological impacts than focusing on skill development, such as singing or playing an instrument. Appreciation for music is, in short, not enough to foster longlasting effects, with skill being paramount.

Discussion

The neurological and brain-based education literature aligns with each other in certain ways while diverging considerably with respect to thematic content. Additionally, several studies examined herein bridged both the neurological and educational domains by highlighting a scientific basis for classroom recommendations. The dominant themes in the neurological literature were related to the emotional responses of the brain to music, the relationship between brain development, plasticity, and music, and the role of creative experiences in promoting synaptic growth. The brain-based education literature varied considerably, with a range of criticisms targeting the empirical ground for brain-based education. Knowledge and skill transfer was a core theme with respect to brain-based education discourse, with very few studies highlighting a neurological basis for transfer. However, several studies that bridged both the brain-based education and neurological domains asserted the prominence of the creative experience, which engages multiple brain areas, in supporting transfer. A dearth of studies examined the practical, classroom considerations for music education with a neurological basis, however, warranting that future research focus on ways in which music education can specifically support transfer to multiple domains and, more saliently, to the extra-academic environment.

The following discussion outlines the literature's dominant themes, affords particular attention to ways in which to bridge the research-practice gap, and recommends future directions for both empirical research and classroom practice. Key strengths and weaknesses in the existing literature are identified in order to remain objective, with the qualitative component of the systematic literature review grounded in the identification of biases as well as central themes. In returning to the outlined research questions, the literature highlighted how brain-based education discourse relates to the neuroscientific literature and, more saliently, how neuroscientific conclusions can optimally manifest in the classroom.

Synthesising the Literature's Dominant Themes

The most weighted themes in the literature, both neuroscientific and academic in nature, suggest that emotions play a central role in enhancing the musical experience as it pertains broadly to learning. Patterson and Perlstein (2011), Schubert (2007), and Strickland (2001) cited that the nature of emotional change caused by a musical experience stimulates multiple areas of the brain simultaneously, with Strickland (2001) arguing specifically that the most meaningful music learning occurs when an emotional shift affects the individual; this shift, in turn, fosters synaptic growth at a higher rate than would have occurred in the absence of emotional change. Patterson and Perlstein (2011) extend this notion by arguing that emotional changes occurring during the learning of new material support the cognitive integration of new material. Schubert's (2007) study cited that the emotional content of music impacts the emotional state of the listener or performer directly, rendering emotional music potentially integral to cross-disciplinary classroom environments.

Brain growth is inextricably bound to its unique plasticity prior to adolescence, with emotions representing a key force linked to both problem-solving and sensory experience. The brain-based education literature emphasises the importance of improvisation, experimentation, and creative experiences in general in promoting learning, with the neurological literature grounding this by asserting that memory is enhanced when the prefrontal cortex is cultivated through creative experiences (Patterson and Perlstein, 2011). A key theme in the neurological literature, not present in the studies focused on education alone, is the relationship between changes in the environment and synaptic growth.

Cohen (2002) and Strickland (2001) posit that changes in the emotional state in conjunction with environmental shifts promote synaptic growth. During childhood, the impact of this combination of forces on the brain appears to be even more formidable due to the plasticity of the brain at this time. Overall, the neurological basis for music-supported learning appears to be inextricably bound to the ways in which the brain receives and processes music. Patterson and Perlstein (2011) and Talay-Ongan (2000) cite that the ways in which both hemispheres are engaged during the musical experience is unique, with the latter author suggesting that music is one of the only external stimuli that can have the bi-hemispherical effect on the brain. Madrazo and Motz (2005) highlights that the ways in which the right and left brain interact to process complex stimuli enhances cognition. Overall, the literature offers support for music's ability to engage multiple brain areas simultaneously, with the multi-location stimulation then optimising cognition.

The educational literature examined the nature of brain plasticity during childhood, asserting that the plastic nature of the young brain renders it particularly conducive to music learning. Fedorenko et al. (2009), Gardiner (2000), and Johansson (2002) assert that the developing brain can change shape when the child is engaged frequently with musical experiences, with the latter two authors suggesting that skill development is critical to brain plasticity. While Fedorenko et al. (2009) asserts that neural imaging highlights similar brain activity among musical performers and those listening or passively receiving music, both Gardiner (2000) and Johansson (2002) contend that it is musical skill that is paramount to promoting the most enduring cognitive effects of music learning.

The primary conflicts existing in the literature were two-fold; with respect to brain-based education literature, the studies either offered theoretical and empirical support for brain-based education, much of which connected musical experience to math or language, or fervently condemned the tendency of brain-based educators to boast scientific foundations where none, in fact, exist. Both Bruer (1999) and Sternberg (2008) argue that while brain-based education may have valid components, the tendency to blindly accept conclusions regarding multiple intelligences and the importance of optimising brain shape during primary school is a disserving one. Sternberg's (2008) assertion that brain-based education should be viewed as a metaphor and not a science, however, is markedly bold considering the clear empirical ground for many of brain-based education's conclusions. Those supporting brain-based education highlight the prominence of the creative experience in stimulating multiple brain areas as well as the role of emotion in boosting cognitive capacity, and the neurological literature lends credence to the importance of creative, and musical specifically, experiences in supporting synaptic growth and memory storage.

An additional conflict in the literature relates to the ways in which musical experiences should be engrained into the academic realm. While some authors contended that any musical experience is a positive one that will promote transfer of knowledge (Talay-Ongon, 2000), others more convincingly suggest that knowledge transfer occurs slowly over time due to small, incremental, neural shifts that take place when the student is exposed to music. Gardiner (2000) also argues for a reframing of transfer through which the notion that knowledge or skill is somehow relocated following or during a musical experience is discounted for the more likely notion that the knowledge or skill stored in the brain is changed during the transfer process. The same author highlights that cognitive skills, such as attentiveness or engagement, are more likely to transfer than other types of knowledge, with an emphasis on skill rather than appreciation paramount to music education. Catterall (2001) asserts that the arts, uniquely, influence skill transfer more so than other subject areas, with cross-discipline transfer of skills learned in reading to math, for example, being only narrowly evident.

A gap in the literature exists with respect to practical ways in which musical experiences should be implemented into the classroom. In order to foster brain plasticity, the neurological literature clearly mandates music education during the primary school years, with even early child education supportive of music learning. Gardiner (2000) asserts that it is unfortunate that so many music education programs focus on mere appreciation, which does little to foster long-lasting transfer effects. Learning how to play a musical instrument during the primary school years, specifically prior to adolescence, is central to garnering the optimum benefits from music learning.

A key assertion made by Gardiner (2000) is that practical, skill development and direct interaction with music is key to fostering the most optimum outcomes. While some brain-based and neurological studies suggest that mere exposure to music facilitates changes, particularly with respect to emotional shifts, Gardiner's (2000) study highlights that that transfer is far more long-lasting and far-reaching if direct, musical experiences can be facilitated (Schubert, 2007). The implications of the literature for bridging the research-practice gap are many and varied, with music teaching a necessary component of any classroom, particularly during the elementary grades during which students can benefit from brain plasticity.

Long-term influences of music education during childhood are apparently supported by music's unique ability to link the right and left brain. Taly-Ongan (2000) implies that few other stimuli will encourage a right-left brain union, thereby rendering music an accessible and highly impactful teaching tool. The following section outlines the ways in which to bridge the research-practice gap in the academic setting.

Music Teaching Practice with a Neuroscientific Ground

In forging connections between the reviewed studies that can be practically implemented into music teaching practice, the role of emotion and musical skill appear to be integral to fostering both transfer and enhanced cognitive capacity. While no studies reviewed herein examined how the emotional shifts occurring during musical experience can be used practically in order to boost the learning experience in the classroom, the number of studies suggesting that the role of emotion is critical to both the musical experience as well as cognitive processing warrant attention be paid by educators to the prominence of the students' emotional experience. The goal emerging from the literature is to use music to catalyse an emotional change through which the information or skill being learned is emotionally perceived differently following the initial perception, processing, and storage of information. Music has a similar impact on the brain, with an initial musical experience stimulating multiple brain areas that will, in turn, engage other areas of the brain during a second musical experience. Educators can then use non-distracting background music to support emotional changes during the learning experience. Music educators, specifically, can sensitise students to the emotional impact of music on their brains by listening to various songs in conjunction with being exposed to a picture of a certain stimulus; a different song, embodying a different emotion, can then be played while students view the same picture, concluding with discussion regarding how the musical experience affected feelings toward the picture.

Perhaps one of the most salient points emerging from the literature is the notions of both plasticity and transfer as being optimally supported through the acquisition of a musical skill. A pervading weakness in the literature was, despite the scholarly nature of all reviewed studies, the failure to distinguish between the types of musical experiences with respect to the impacts had on the brain. Particularly the brain-based education literature struggled to convincingly articulate which musical experiences were the most optimal in supporting the cognitive benefits of transfer. Namely, only Catterall (2001) and Gardiner (2000) asserted the importance of musical skill in promoting cognitive advantage, with the bulk of the other studies either ignoring the need to distinguish between the neural processes engaged during various musical experiences or, less often, asserting that playing an instrument had effects similar to listening to music (Fedorenko et al., 2009).

In order to meaningfully integrate the literature's conclusions into classroom practice, it is clear that emotional changes fostered by music in conjunction with the cultivation of musical skill are critical to enhancing cognitive capacity. The primary school years are particularly pivotal due to enhanced brain plasticity, with enduring, neurological effects evident for children who are musically active prior to adolescence. Future research should, by extension, seek to fill in the gaps existing in the literature and examine the ways in which music education can be integrated into other academic dimensions, encouraging overlap between subject areas.

The literature provides clear and valid ground for integration of musical experiences into the classroom. It is human to engage in creative experiences of all types, and brain development is supported through artistic expression and interaction with the arts in general. Undergirding the literature is the assumption that all individuals embody the capacity to engage with music; there is no implication that certain students are unable to benefit from music's integration in the classroom, though the literature suggested narrow ground for genetic predisposal toward musical intelligence. Overall, it is human to create and appreciate music, with an innate predisposal for musical intelligence neurologically embedded.

The research highlights the complexity of the ways in which the brain processes music, with Taly-Ongan (2000) asserting that music represents a unique stimulus binding the right and left brain during cognitive processing; the role of emotions in catalysing or emerging from this link was not apparent in the literature, and future research should focus on musical stimuli's impact on both emotions and right-left brain connections simultaneously. Additionally, the research on knowledge and skill transfer did not highlight the importance of emotions or the role of right-left brain connections at all, though transfer may well be facilitated by the other two variables given the existing evidence.

In short, practical integration of the literature's conclusions in the classroom depends on the acknowledgment and practical manifestation of the following themes: emotions, right-left neurological connections, long-term transfer of knowledge and repeated musical experiences, and the pre-adolescent period. The child's brain is clearly particularly conducive to musical experiences in the classroom, with singing, playing an instrument, dancing, and other direct engagement more meaningful in terms of brain development than listening to a piece of music.

The impact of music on the brain facilitates learning and memory, with changes in the environment, such as the playing of a song, encouraging a shift in the emotional state of the listener in a way that creates synaptic growth (Cohen, 2002). If a student is learning new material or engaging in self-directed learning for example, playing a song in the classroom or integrating learning with song may well facilitate knowledge acquisition. Future research should focus on the ways in which music's practical manifestations in the classroom facilitate cognitive processing and long-term memory storage. At present, the brain-based education literature appears to be largely theoretical rather than empirical, which is precisely the reason why authors target the philosophy as a metaphor and not a science.

The research provides a firm foundation for empirical exploration of music education's role in both the dedicated and general education classroom. Overall, the importance of music in creating optimal opportunities for learning is largely irrefutable, with no studies suggesting that music has no impact whatsoever on learning or the brain. The studies suggesting that brain-based education lacks scientific ground are, however, at least partially correct in their acknowledgement of only narrow empirical evidence for the marriage of neuroscience and brain-based education. However, the neurological research emphasizing music's clear ability to facilitate learning warrants future research be conducted regarding music, emotional responses, and learning in the classroom.

Additionally, while the focus is intently on the pre-adolescent period due to the significant plasticity, music may well support learning later in life, as well. Patterson and Perlstein's (2011) contention that the human brain remains plastic throughout adulthood implies that while the benefits of music may be weakened somewhat post-adolescence when the brain becomes less plastic, synaptic growth can be fueled by music throughout an individual's lifetime. The marriage of neuroscience and music education then has significant implications for both primary and higher level learning.

The most significant gaps in the literature emerged from a lack of connections between dominant themes. In short, while significant ground existed for the prominence of emotions, the importance of creative experiences, music's impact on cognitive processing, and knowledge transfer with respect to learning, no single study significantly examined any two or more of these variables. Successful implementation of musical experiences within either the dedicated or general education classroom in a way that facilitates learning and cross-subject transfer depends on the more thorough examination of these variables in order to reduce negative perceptions of brain-based education.

It may be necessary to extricate music's neuroscientific ground from brain-based education altogether in order to support the already valid conclusions regarding music's impact on learning. The brain-based education literature fails to justly support the complexity of the brain's cognitive processes that occur while listening or otherwise engaging with music, but the lack of empirical ground should not condemn the future of music's role in the classroom. In essence, this literature review can provide a firm foundation for further exploration of music's integration in the classroom, particularly as emotional responses in students encourage knowledge acquisition, but more scientific research is needed in order to counter the thus-far valid claims made by brain-based education's critics.

The key strengths of the literature are rooted in the marked lack of conflicting assertions and conclusions. Strong parallels exist between the education and neurological literature, particularly with respect to creative experiences and synaptic growth during the pre-adolescent years, and very few conflicting conclusions exist within the literature overall. The skepticism brain-based education's critics is rooted primarily in the absence of empirical ground and failure of education's literature to acknowledge the neurological complexity of the learning process; this review lends partial credence to this critique in that more empirical evidence is urgently warranted within the brain-based education field in order to facilitate the union between neuroscience and music education, a union that is not only possible but necessary given music's ability to uniquely support brain development.

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