Abstract
Word learning constitutes a human faculty which is dependent upon two anatomically distinct processing streams projecting from posterior superior temporal (pST) and inferior parietal (IP) brain regions toward the prefrontal cortex (dorsal stream) and the temporal pole (ventral stream). The ventral stream is involved in mapping sensory and phonological information onto lexical-semantic representations, whereas the dorsal stream contributes to sound-to-motor mapping, articulation, complex sequencing in the verbal domain, and to how verbal information is encoded, stored, and rehearsed from memory. In the present source-based EEG study, we evaluated functional connectivity between the IP lobe and Broca’s area while musicians and non-musicians learned pseudowords presented in the form of concatenated auditory streams. Behavioral results demonstrated that musicians outperformed non-musicians, as reflected by a higher sensitivity index (d’). This behavioral superiority was paralleled by increased left-hemispheric theta coherence in the dorsal stream, whereas non-musicians showed stronger functional connectivity in the right hemisphere. Since no between-group differences were observed in a passive listening control condition nor during rest, results point to a task-specific intertwining between musical expertise, functional connectivity, and word learning.
Highlights
In the last two decades, professional musicians have repeatedly been shown to serve as a reliable and powerful model for studying functional and structural plasticity in brain regions supporting auditory perception[1,2,3,4,5], motor control[6,7,8], and recently higher cognitive functions[9,10]
The multifaceted influence of music training, and investigated the neural signatures underlying word learning mechanisms in musically trained and untrained subjects[40,41] and children undergoing music training[42] while the participants learned the meaning of new words through word-picture associations of increased mnemonic complexity. Results from these studies showed a behavioral advantage of musicians and musically trained children in word learning, only when participants had to access semantic memory in order to judge whether new pictures were related to previously learned words
According to previous studies showing a positive relationship between functional connectivity in the left dorsal stream and word learning in musicians and non-musicians[41,67] as well as on anatomical data indicating an optimization of the left dorsal stream as a function of music training[13,14], we evaluated functional connectivity between the inferior parietal (IP) lobe and ventral part of the prefrontal cortex, and predicted that the behavioral advantage of musicians in word learning would be reflected by an increased left-hemispheric asymmetry
Summary
In the last two decades, professional musicians have repeatedly been shown to serve as a reliable and powerful model for studying functional and structural plasticity in brain regions supporting auditory perception[1,2,3,4,5], motor control[6,7,8], and recently higher cognitive functions[9,10]. By using a multimodal imaging approach, Lopez-Barroso and colleagues[67] reconstructed the posterior, the anterior, and the long segment of the AF68,69, and revealed a positive correlation between functional and structural connectivity among Wernicke’s area and Broca’s territory (i.e., long segment of the AF) and the ability of the participants to remember pseudowords presented in the form of auditory streams These results suggest that the learning of pseudowords leads to an increased recruitment the left dorsal stream, and that sensory-to-motor coupling mechanisms may contribute to generate the motor codes of new phonological sequences for facilitating verbal memory functions[49,70]. Previous fMRI studies investigating the neural underpinnings underlying word learning mechanisms by using picture-word associations[64,71] or visually presented sentences[72], generally revealed increased brain activity in distributed neocortical areas situated along the two processing streams and accommodating lexical-semantic processes[47,51], including the IP lobe, Broca’s area, and the middle-posterior part of the middle temporal gyrus (MTG)
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