From dysfunctional to extraordinary verbal repetition abilities: clinical implications and neural features

Abstract

Verbal repetition and audio-visual imitation stand as crucial functions for the acquisition and maturation of language in childhood, language learning in adulthood, and a major resource for language recovery after brain damage. Although modern neuroimaging techniques have allowed the identification of the brain areas involved in repetition tasks in healthy subjects, many clinical and neural aspects of this linguistic function are still overlooked in persons with aphasia and in emerging models of language expertise. Therefore, the present dissertation aims to explore cognitive correlates and neural features of verbal repetition from different perspectives including models of dysfunctional repetition (i.e., people with aphasia) and language expertise (i.e., healthy backward speakers). Generally, this thesis explores the potential of the dorsal and ventral components of the neural network supporting verbal repetition to assume, under certain circumstances (e.g., brain damage or extraordinary abilities), non-canonical functions. Further, this dissertation addresses clinical issues of some aphasic symptoms characterized by uncontrolled repetition (i.e., echolalia), as well as reviews sex as a source of variability in verbal repetition outcomes after brain damage. This dissertation includes five studies that are part of this dissertation. First, it reviews the mechanisms involved in dysfunctional repetition, especially in two repetitive verbal behaviors named conduite d’approche and mitigated echolalia (Study 1) and addresses clinical issues of the last one (Study 2 and 3). In this regard, Study 1 proposes that in the context of aphasia these symptoms (i.e., conduite d’approche and mitigated echolalia) may represent active attempts of verbal communication, rather than inconsequential repetitive verbal behaviors resulting from maladaptive neural changes.