Verbal repetition and imitation are crucial skills in various forms of language learning that aim at building up functional communication in daily life. Although verbal repetition entails the imitation of incoming auditory stimuli, it also benefits from visual signals, such as mouth and lip movements. This range of audiovisual input underlying verbal repetition and imitation is likely to depend on the conjoint activity of intermingled mirror neuron systems and white matter tracts. A series of recent articles presented original data and insightful reviews of the literature on the role of white matter pathways during intact and impaired verbal repetition and imitation learning - a considerable body of results has been compiled in a Research Topic of Frontiers (Berthier and Lambon Ralph. Front Hum Neurosci. 2014 Oct 2; 8: 727. doi: 10.3389/fnhum.2014.00727). This fruitful proliferation of data provides a suitable framework to further explore the effect of audiovisual verbal repetition and imitation training on neural plasticity in persons with speech and language disorders.

Converging neuroscience evidence suggests that neural plasticity may be more pronounced if training is grounded in experience. However, little research to date has explored the influence of verbal repetition and imitation on functional connectivity as well as on grey matter structure (mirror neuron system, frontal, temporal and parietal cortices, and basal ganglia) and white matter tracts (dorsal and ventral streams) to support language function in both healthy individuals and persons with communication disorders. Moreover, it is not fully understood to what extent emergent biological interventions (non-invasive brain stimulation, drugs) contribute to the efficacy of seminal approaches in speech and language rehabilitation after acquired brain injury. Therefore, studies examining the effect of behavioral training alone and augmented with biological interventions on brain plasticity as measured with functional magnetic resonance imaging fMRI, resting state fMRI, magnetoencephalography, diffusion tensor imaging, and voxel-based morphometry, are strongly needed.

Articles in the current Research Topic will tackle many different and critical new questions, including: (1) Does training of verbal repetition and imitation skills lead to better outcomes in therapy in persons with speech and language disorders when compared to other interventions? (2) Does such an effect translate to both speech production and functional communication, as demonstrated in standardized language tests? (3) How are verbal stimuli (words, pseudowords, grammatical utterances, formulaic language), expressive features (prosody, melodic contour, rhythmicity) and visual information (pictures, videos) associated with therapy outcomes? (4) Which functional changes in brain activation and connectivity may result from these therapies? (5) Which are the structural changes in grey matter structure and white matter pathways promoted by these interventions? (6) Is there individual variability in the functional- structural plasticity induced by verbal repetition-imitation training and supplementary interventions (biological treatments)? (7) Does arrested development (hypoplasia) of right hemisphere white matter pathways or damage to these bundles in the left hemisphere predict response to repetition and imitation training?

We welcome all submission formats, with emphasis on the following Frontiers Article types: Original Research, Clinical Trials, Case Reports, Mini-Reviews, Opinion, Perspectives, and Technical Reports. Manuscripts, although of an interdisciplinary nature, must have a primary focus on the impact of training and rehabilitation on neural structure and function.

Important Note: All contributions to this Research Topic must be within the scope of the section and journal to which they are submitted, as defined in their mission statements. Frontiers reserves the right to guide an out-of-scope manuscript to a more suitable section or journal at any stage of peer review.