Editorial
Abstract
Neuroplasticity is the ability of neurons to modify connections. Music has been proven to cause structural and functional changes in different areas of the brain. These changes also lead to the development of skills that may or may not be related to music. The mechanism behind these changes is not completely known however few hypotheses have tried to explain it such as the activation of the dopaminergic mesolimbic system. The association of brain plasticity with music has allowed researchers and clinicians to develop various music-based interventions. These interventions have been found useful in patients of stroke, dementia, Parkinson’s, epilepsy etc.
Music, don’t we all love it? The best escape there is, transcending into realms of an overwhelming number of emotions. These emotional overflows brought by music make it the perfect, inseparable companion. The extraordinary extent to which humanity listens to music, makes one wonder, does this change us somehow?
Before we begin to understand the changes that occur due to music, we need to learn what change means when it comes to the brain. Plasticity, right. A term which was first described in 1890 by William James as “the possession of a structure weak enough to yield to an influence, but strong enough not to yield all at once.” In 1904, Ramón y Cajal elaborated on this idea in the neuroscientific context. He proposed that in order to fully understand the complex phenomenon of music induced plasticity, one must acknowledge the formation of new pathways through ramification, and progressive growth of the dendritic arborization and the nervous terminals, in addition to the reinforcement of pre-established organic pathways.1 In the simplest terms, brain plasticity is the ability of the brain to form new synaptic connections and strengthen the old ones.
One of the reasons why brain plasticity is so fascinating is that until a while back, it was believed that plasticity is only a feature of a child’s brain, not the adult. However, we have enough evidence now to suggest the contrary. Almost every part of the brain is plastic, however it has particularly been seen in the adult hippocampus, along with certain regions in the temporal and parietal lobe.[2][5][6]
To figure out how music changes our brain, scientists compared the brains of non-musicians with musicians through a battery of tests (MRI, fMRI, TMS, MEG, EEG), to find both structural and functional changes. One of the first structural findings was a larger middle section of the corpus callosum. Increased gray matter in the inferior frontal cortex which contains Broca’s area, the center of speech, is also seen. Expert musicians have differences in planum temporale, also known as the secondary auditory cortex, located in the superior temporal gyrus. Prominent leftward asymmetry of planum temporale is linked to the ability to perceive absolute pitch. Other areas that show structural differences include the Heschl’s gyrus, also known as the primary auditory cortex, cerebellum, superior parietal lobule, motor and sensorimotor cortices. These areas have a thicker cortex and greater volume.[5][6] In simpler words, it’s like the parts of your brain that are concerned with sound are all buffed up after hitting the gym.
Functional changes include stronger responses in higher auditory regions allowing musicians to process auditory responses with lesser neuronal resources. There is increased representation for the little finger of the left hand in (right-handed) string players, and increased representation areas in the auditory cortex for tones, pitch and timbre. There is also evidence for better multi-sensory encoding and integration in musicians. Both the structural and functional changes are more pronounced in people who began training early in life, usually before the age of 7, and who practiced with greater intensity.[3][4]
These structural and functional changes are seen in trained musicians. However, short term changes have also been observed in people who just listen to music. The benefits of these changes are not only confined to motor and sensory musical activities. In fact, it ‘spills over’ to other domains as well. This phenomenon is known as transfer which has been divided into two categories by researchers, near transfer and far transfer. Near transfer is when the manifestations of these plastic changes lead to a skill gain that is similar to the motor skill required to play the music. For instance, learning a musical instrument enhances fine motor skills which in turn helps to enhance a skill like typing. On the other hand, far transfer is when the non-musical skill does not have much resemblance with the musical skill. For instance, musical training being associated with mathematical skills, intelligence quotient, spatial thinking etc. However, near transfer is a more frequently observed phenomenon than far transfer. [6][7]
Getting to know the multitude of neuroplastic changes, one is intrigued by the mechanisms behind it. What exactly is going on? Well, the specific cellular and molecular mechanisms behind music-induced brain plasticity are unknown as of now. We do have certain hypotheses trying to explain these. These revolve around neuronal hypertrophy, increased volume of neuropil, and changes in the vascular or glial compartments. Activation of the dopaminergic mesolimbic system, leading to increased dopamine levels is putatively the mechanism behind cognitive-emotional gains.[8] The reason behind music specifically activating only certain areas in the brain is not yet known, the best speculations being phylogenetic, i.e., music might have an evolutionary advantage.10 Hopefully, further research will shed light on this.
The current understanding of music-induced neuroplasticity has paved the way for music-based interventions. These interventions focus mainly on the rehabilitative potential of music in several neurological diseases. Stroke, dementia, Parkinson’s disease, epilepsy, multiple sclerosis etc. to state a few. Music-based interventions include music therapy, music medicine, rhythmic auditory stimulation, music supported therapy and melodic intonation therapy. Each modality of treatment has a different approach. Many studies have reported enhanced motor and cognitive recovery in patients of stroke who were rehabilitated with a music-based intervention. Improvement in cognitive performance was seen in patients with dementia. It also had a positive impact on neuropsychiatric symptoms and mood disorders associated with dementia. These interventions were helpful for people with Parkinson’s disease as well. It was found that rhythmical use of musical stimuli compensates for the loss of control by the extrapyramidal system, enhancing audio perception and movement synchronization. Music acts as an external cue for movement, thereby acting as a substitute for the deranged internal timing function in people with Parkinson’s disease. Similarly, a significant reduction in seizure frequency was seen in people being rehabilitated with music-based interventions.[8][9][10]
Our understanding of what music does to our brain is developing each day. With newer testing modalities, we can probe deeper into the effects that music has on our brain. This will lead to even better intervention strategies. Music is special to all of us. However, knowing the extent to which music affects and modifies us makes us appreciate it even more. So, what are you waiting for? Go, start learning an instrument. Start singing. Start enjoying music. Change your brain.
REFERENCES
y Cajal, Santiago Ramón. "Textura del Sistema Nervioso del Hombre y de los Vertebrados, 1899–1904: ". Stripped Bare: The Art of Animal Anatomy, Princeton: Princeton University Press, 2018, pp. 216-219. https://doi.org/10.1515/9780691183978-016
Demarin V, Roje Bedeković M, Bosnar Puretić M, Bošnjak Pašić M. Arts, brain and cognition. Psychiatria Danubina. 2016 Dec 12;28(4):343-8.
Altenmüller E, Furuya S. Brain plasticity and the concept of metaplasticity in skilled musicians. Progress in motor control. 2016:197-208.
Johansson BB. Music and brain plasticity. European Review. 2006 Feb 1;14(1):49.
Schlaug G. Musicians and music making as a model for the study of brain plasticity. Progress in brain research. 2015 Jan 1;217:37-55.
Wan CY, Schlaug G. Music making as a tool for promoting brain plasticity across the life span. The Neuroscientist. 2010 Oct;16(5):566-77.
James CE, Altenmüller E, Kliegel M, Krüger TH, Van De Ville D, Worschech F, Abdili L, Scholz DS, Jünemann K, Hering A, Grouiller F. Train the brain with music (TBM): brain plasticity and cognitive benefits induced by musical training in elderly people in Germany and Switzerland, a study protocol for an RCT comparing musical instrumental practice to sensitization to music. BMC geriatrics. 2020 Dec;20(1):1-9.
Sihvonen AJ, Särkämö T, Leo V, Tervaniemi M, Altenmüller E, Soinila S. Music-based interventions in neurological rehabilitation. The Lancet Neurology. 2017 Aug 1;16(8):648-60.
Hallam S, Cross I, Thaut M, editors. Oxford handbook of music psychology. Oxford University Press; 2011 May 26.
Reybrouck M, Vuust P, Brattico E, IntechOpen. Music and brain plasticity: how sounds trigger neurogenerative adaptations. Neuroplasticity Insights of Neural Reorganization. 2018 Jun 6;85.
About the authors
Dr Harsh Srivastava is a MBBS Intern at Uttar Pradesh University of Medical Sciences, India. He has a deep interest in neuroscience and evolutionary biology. Currently he is an associate editor here at Project Encephalon.
Gmail- harsh.sri.upums@gmail.com
Twitter- @_telomerase
Instagram- @molecular.chaos
Bhagyajyoti Priyadarshini is an aspiring physician-scientist with special interest in the fields of neurology and public health. Currently she is pursuing her MBBS from SLN Medical College and Hospital, Koraput, Odisha. She has been doing research from the first tear of her MBBS and has received several national and international recognitions for her work.
Gmail- luckybhagyajyoti@gmail.com
Instagram- @lucky.bhagyajyoti