One of the most devastating consequences of a left-hemisphere stroke (CVA) is aphasia, the loss of language abilities. People who experience aphasia encounter sudden, debilitating, compromised ability to produce and/or comprehend spoken and written language. The impairment is characterized by great variability and is associated with the site and the size of the brain lesion and with a number of personal and external variables (e.g., concomitant diseases, access to care). The degree of recovery from aphasia is associated, similarly, with the extent of the lesion and of the impairment. Despite the promise of recent evidence for neural plasticity in the adult brain – with studies demonstrating neuronal reorganization and growth even in adulthood – recovery from language impairment following a CVA is typically slow and almost always incomplete.
The study of speakers of two or more languages who have aphasia offers a unique opportunity to better understand brain-language relations and enhance language rehabilitation practices. Multilingual individuals with aphasia often exhibit complex patterns of impaired and spared abilities across their languages. Factors, such as level of language proficiency, age and manner of language acquisition, and frequency of use of each language, as well as the degree to which the languages share grammatical and lexical components may determine patterns of differential impairment in multilingual aphasia.
The objective of the funded research project is to help resolve currently competing theories about the underlying representation of multiple languages in the brain. This will be achieved by conducting two related studies, one designed to identify what neurological and linguistic variables predict whether a focal brain lesion in multilingual individuals will result in similar deficits in all the languages versus distinct deficits in different languages. The second study will determine what variables contribute to positive effects in one language following treatment in another. The results of these studies will contribute to the development of theories for how linguistic and proficiency similarities among multiple languages determine their organization in the brain and affect processes of reorganization during recovery from brain injury. Furthermore, results from this research project will help predict treatment outcome and guide clinical choices for rehabilitation of people who experience devastating language deficits that impair their communication, productivity, and sense of identity.