Aphasia Treatment Potential High Note of Musician Brain Study

Damian McNamara

September 14, 2018

Professional beatboxers show greater activity in multiple areas of the brain when they listen to beatboxing clips. Expert guitarists also experience similar selective sensorimotor activity when they hear guitar music, although in different brain regions that correspond more to hand control than mouth movement. 

In contrast, functional MRI (fMRI) shows that nonmusicians did not exhibit similar selective brain activity when listening to the same music, suggesting the findings relate to expertise-specific neurologic changes and not increased attention while listening to the music.

This is the first study to examine differences in the brain activity of professional musicians outside of classical music. The findings may someday help clinicians orchestrate effective therapies for people with aphasia and other neurologic disorders.

Dr Sophie K. Scott

"We are very interested in the way that music expertise affects the brain, as we are keen to identify — with this and further studies —  the extent to which this expertise might overlap with classic language networks," study author Sophie K. Scott, PhD, Wellcome senior research fellow in basic biomedical science and professor of cognitive neuroscience at University College London, United Kingdom, told Medscape Medical News.

Scott and colleagues also are interested in "to what extent we can understand and promote recovery from aphasia by addressing nonverbal aspects of vocal production."

The study was published online August 31 in Cerebral Cortex.

Professional Expertise Instrumental

The researchers scanned the brains of 20 beatboxers, 20 guitarists, and 20 nonmusicians. The beatboxers showed greater activity in the superior temporal gyri, cerebellum (lobule VI), the supplementary motor area, the inferior frontal gyrus bilaterally, and the left precentral gyrus when listening to beatboxing compared with guitar music. Beatboxers showed increased activity in only one area of the brain — the right middle occipital gyrus — when listening to guitar music.

Guitarists, on the other hand, showed greater activity in the left inferior parietal cortex, left inferior frontal cortex, left inferior temporal cortex, and supplementary motor area when listening to other professional guitarists compared with listening to beatboxers.

Similarly, guitarists showed increased activity in only one brain region, this time the bilateral superior temporal gyri, when listening to the beatboxers.

Interestingly, nonmusicians also showed more activity in the bilateral superior temporal gyri while listening to beatboxing compared with guitar music. Otherwise, this group did not differentially activate dorsal stream regions for beatboxing or guitar music.

Beatboxers use their vocal tract to produce polyphonic music, during which they often closely mimic musical instruments. Harry Yeff, a coauthor on the paper and professional beatboxer known as Reeps One, created novel beatboxing tracks for the study.

Coauthor Harry Yeff, also known as beatboxer Reeps One. Courtesy of Reeps One

Only unfamiliar beatboxing and guitar tracks were included to avoid dorsal stream activation associated with rehearsal or familiarity with the music.

The beatboxer participants had an average 8 years of professional experience and 11 years of amateur beatboxing experience. The guitarists had 9 years of professional experience and 12 years of amateur experience. Interestingly, none of the guitarists could beatbox, but five of the beatboxers reported some guitar experience.

All study participants completed hearing and cognitive testing. The three groups were similar in terms of age, nonverbal IQ, and working memory.

Previous research suggests a feature of classical musical expertise is greater activity in dorsal stream regions when listening to music. The current investigators predicted beatboxers and guitarists would use different motor effectors to create their music and in turn display distinct patterns of dorsal stream engagement on fMRI scans.

Participants were instructed to remain motionless in the fMRI scanner. Participants listened to 32 clips of beatboxing and 32 clips of guitar music, interspersed with rest, and then repeated the protocol. Each music clip was 3 to 5 seconds long.

The investigators used a 1.5-T Siemens Avanto scanner with a 32-channel receive-only head coil. The fMRI images were acquired by using a T2-weighted gradient-echo planar imaging sequence.

Following the listening portion, participants also completed a mouth and hand localizer, moving their hands or mouths in a sequence of actions in response to visual prompts during fMRI.

Implications for Stroke?

The researchers found beatboxers recruited mouth areas when listening to beatboxing, and guitarists recruited hand areas when listening to guitar music. This finding further supports specific sensorimotor activity vs broad, unspecific attentional activity in the brain.

Crossover effects also point to more specific brain activity. When listening to music in their genre of expertise, participants showed greater crossover activity in the left and right inferior frontal cortex, left and right cerebellum, left and right inferior temporal cortex, and supplementary motor area.

This interaction between effector region and group was significant (P = .033). In contrast, wider hemispheric effects were not significant (P = .93), nor were interactions between the hemisphere and group or effector region (P > .7)

These findings suggest that musicians are not simply paying more attention to sounds with which they are more familiar, the researchers note.

"It is rather suggestive, we argue, of a more specific mechanism — they might be engaging sensorimotor mechanisms more strongly when their previous experience provides them with the sensorimotor repertoire to do so.

"Our results establish that long-term sensorimotor experience relates to a stronger engagement of dorsal stream regions during perception," the researchers added, "a finding that is particularly important to understanding how individual experiences might shape brain activity," they write.

"We are interested in brain plasticity and how we can better understand this to aid neurologists and other clinicians who work with stroke patients," Scott said.

"One interesting finding here was that though the expertise effects were musical, the results were left lateral sided, which may have important implications for aphasia," Scott said.

Beatboxing as Vocal Exercise?

The researchers also examined activity in 12 different neural networks using a multivariate analysis. Specifically, they performed an independent component analysis to reveal information in the data not seen in a univariate analysis.

For example, when the musicians listened to their own genre, they recruit auditory-motor and sensorimotor networks. At the same time, they inhibited domain-general networks, including default mode and executive control networks.

The same findings were not observed among the nonmusicians.

How sensorimotor and attentional networks interact could be a focus of future studies. The investigators would also like to explore any network-level changes associated with musical expertise over time.

Clinical application studies also are warranted.

"For example, one direction that I am very interested in is how we can try to develop novel tools and techniques for neurologists and speech and language therapists based on the beatboxing skills — and other kinds of vocal expertise," Scott said.

"We know that melodic intonation therapy [singing the words rather than saying them] can be helpful, so what would be the benefits of incorporating some of the vocal exercises and techniques that the beat boxers use?"

Therapeutic Promise

Commenting on the findings for Medscape Medical News, Anna V. Kasdan, a doctoral student at Vanderbilt University in Nashville, Tennessee, said it's well known that "these same sensorimotor regions are activated in individuals with aphasia — language impairments due to a brain injury —  when singing and speaking. It could be that we can tap into these pre-existing, instrument-specific neural mechanisms to more effectively design speech and music-based therapies.

"Aphasia is a prevalent disorder affecting over 1 million Americans, so the evidence suggesting that expertise-specific neural markers are present in musicians could hold therapeutic promise for musicians recovering from certain neurological and language disorders," she added.

Kasdan published a previous study showing that people with aphasia are better able to retrieve words when singing compared with words spoken in isolation. The results suggest a wider role for music in speech therapy for people with aphasia.

A grant from the Wellcome Trust supported the study. Scott and Kasdan have disclosed no relevant financial relationships.

Cereb Cortex. Published online August 31, 2018. Full text

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