Neuroplasticity and Functional Recovery after Intensive Language Therapy in Chronic Post Stroke Aphasia: Which Factors Are Relevant?

Neuroscience-based interventions for aphasia are among the most promising approaches toward successful language rehabilitation. Associated therapeutic techniques are highly effective in reducing cognitive-behavioral difficulties resulting from brain damage and can induce neuroplasticity (Taub et al., 2002; Berthier and Pulvermüller, 2011). However, it is still not clear how language recovery and reorganization of language is reflected by functional changes manifest in human brain activity. In aphasia research, previous studies addressed the role of the left (LH) and right (RH) hemisphere across the entire recovery phase. It has been suggested that brain reorganization in aphasia is a dynamic process, in which the involvement of perilesional LH regions and RH areas (e.g., Broca-homolog or RH superior temporal cortex, Musso et al., 1999) is dependent on the specific phase of language recovery (Saur et al., 2006). These data highlight the importance to control for time post stroke when investigating treatment-related changes to avoid the influence of spontaneous remission. To date, only few studies have addressed therapy-induced neuroplasticity in patients with post stroke aphasia (PSA), and findings are rather inconsistent. The reasons for the heterogeneity of previous results may be attributed to patient-specific variables such as lesion size and site, symptom severity, etc. (Crosson et al., 2005). While patient-specific variables seem to influence functional recovery, the specific impact of non-patient factors (e.g., neuroimaging method, language task, therapy method,—intensity,—amount, and—duration) has rarely been addressed. However, to maximize therapy outcome, it is important to systematically investigate all possible factors and to identify neurophysiological predictors of recovery. Focusing on intensive, clinically effective, and short-term interventions and on suitable language tasks seems promising to achieve this goal.