Effects of Practice and Experience on the Arcuate Fasciculus: Comparing Singers, Instrumentalists, and Non-Musicians

Abstract

Structure and function of the human brain are affected by training in both linguistic and musical domains. Individuals with intensive vocal musical training provide a useful model for investigating neural adaptations of learning in the vocal–motor domain and can be compared with learning in a more general musical domain. Here we confirm general differences in macrostructure (tract volume) and microstructure (fractional anisotropy, FA) of the arcuate fasciculus (AF), a prominent white-matter tract connecting temporal and frontal brain regions, between singers, instrumentalists, and non-musicians. Both groups of musicians differed from non-musicians in having larger tract volume and higher FA values of the right and left AF. The AF was then subdivided in a dorsal (superior) branch connecting the superior temporal gyrus and the inferior frontal gyrus (STG ↔ IFG), and ventral (inferior) branch connecting the middle temporal gyrus and the inferior frontal gyrus (MTG ↔ IFG). Relative to instrumental musicians, singers had a larger tract volume but lower FA values in the left dorsal AF (STG ↔ IFG), and a similar trend in the left ventral AF (MTG ↔ IFG). This between-group comparison controls for the general effects of musical training, although FA was still higher in singers compared to non-musicians. Both musician groups had higher tract volumes in the right dorsal and ventral tracts compared to non-musicians, but did not show a significant difference between each other. Furthermore, in the singers’ group, FA in the left dorsal branch of the AF was inversely correlated with the number of years of participants’ vocal training. Our findings suggest that long-term vocal–motor training might lead to an increase in volume and microstructural complexity of specific white-matter tracts connecting regions that are fundamental to sound perception, production, and its feedforward and feedback control which can be differentiated from a more general musician effect.

Song and speech: Examining the link between singing talent and speech imitation ability

“…Only very recently have singing and the playing of a musical instrument been laid side by side as separate elements. This view to separate the two has, in recent years, been supported by brain imaging studies which have found that the two skill sets involved lead to increased activity in different areas of the brain (Kleber et al, 2010;Halwani et al, 2011). For example, singers showed greater complexity in certain white matter tracts resulting from their extensive vocal-motor training.…”

“…For example, singers showed greater complexity in certain white matter tracts resulting from their extensive vocal-motor training. This leads not only to an improvement in sound perception and production but also in feedforward and feedback control (Halwani et al, 2011). Increased activity in the primary somatosensory cortex has also been observed in the brains of classically trained singers (Kleber et al, 2010).…”

“…It is very likely, therefore, that the excellent speech imitation ability of a good singer stems from their vocal flexibility which might be the result of their physical training and articuloanatomical endowment. Halwani et al (2011), for example, set singers aside from average people and musicians, because good singers are either aware of the sound production processes or are in the possession of special skills or talents.…”

Differential Adaptation of Descending Motor Tracts in Musicians

“…Several studies have revealed differences in white matter composition when comparing individuals trained in sensorimotor skills with novices (Johansen-Berg et al 2010): for example, a recent study from our group showed that singers exhibited lower FA values than instrumental musicians in the arcuate fasciculus (Halwani et al 2011). Stronger evidence for the effects of training on white matter is available from 2 longitudinal studies reporting FA increases after individuals learned to juggle (Scholz et al 2009) or underwent memory training (Engvig et al 2012).…”

The dynamic imprint of word learning on the dorsal language pathway

“…Auditory and motor areas communicate directly through the arcuate fasciculus (AF), a prominent white-matter tract proposed as participating in audiomotor processing in language and music (Saur et al 2008(Saur et al , 2010Halwani et al 2011). Saur et al (Saur et al 2008(Saur et al , 2010 reported that repetition of pseudowords compared to real words, activated the left anterior and posterior parts of the superior temporal region, along with frontal regions such as the left pars opercularis of the inferior frontal gyrus and the premotor areas (BA 44/6).…”