Experience-dependent changes in functional activation
In string and keyboard players, exceptional skill has been associated with reduced premotor activation and a shift toward more focused (or task relevant) activation in regions related to motor execution—namely, in the primary sensorimotor cortex (Lotze et al. 2003; Haslinger et al. 2004), although decreased involvement of some brain areas has also been reported as a result of more efficient functioning (Jancke et al. 2000). Adaptations on the level of functional or morphologic characterization appear not only as increased cortical representation of hand and fingers (Elbert et al. 1995) but involve also the auditory cortex (Schneider et al. 2002). Corresponding to Hebbian learning (Hebb 1949), cross-modal plasticity has been reported as a consequence of simultaneous integration of auditory and somatosensory signals (Pantev et al. 2003). Other experience-dependent effects in the musicians’ brain involve an increased motor cortical excitability (Rosenkranz et al. 2007), a larger cerebellum (Hutchinson et al. 2003) and anterior corpus callosum (Schlaug et al. 1995) and even a more structured fiber tract organization in white matter (Bengtsson et al. 2005).
Several studies have shown that motor-skill training over extended time periods results in reorganization of neural networks and changes in brain morphology. Yet, little is known about training-induced adaptive changes in the vocal system, which is largely subserved by intrinsic reflex mechanisms. We investigated highly accomplished opera singers, conservatory level vocal students, and laymen during overt singing of an Italian aria in a neuroimaging experiment. We provide the first evidence that the training of vocal skills is accompanied by increased functional activation of bilateral primary somatosensory cortex representing articulators and larynx. Opera singers showed additional activation in right primary sensorimotor cortex. Further training-related activation comprised the inferior parietal lobe and bilateral dorsolateral prefrontal cortex. At the subcortical level, expert singers showed increased activation in the basal ganglia, the thalamus, and the cerebellum. A regression analysis of functional activation with accumulated singing practice confirmed that vocal skills training correlates with increased activity of a cortical network for enhanced kinesthetic motor control and sensorimotor guidance together with increased involvement of implicit motor memory areas at the subcortical and cerebellar level. Our findings may have ramifications for both voice rehabilitation and deliberate practice of other implicit motor skills that require interoception. Country:Italy