Neuroplasticity Mechanism in Post-Stroke Language Recovery

Abstract

Introduction: Recovery from post-stroke aphasia is highly variable. A central clinical dilemma is that existing neuroplasticity models offer conflicting predictions: the vicariation model recommends recruiting contralesional right-hemisphere regions, while the interhemispheric competition model advocates inhibiting them. This disconnect directly impacts neuromodulation decisions. Objective: This review synthesizes current evidence on neuroplasticity mechanisms in aphasia recovery and proposes a clinically applicable framework to reconcile competing models. Results: The bimodal balance–recovery model integrates both frameworks by demonstrating that the optimal strategy depends on structural reserve. Patients with preserved ipsilesional white matter integrity (e.g., arcuate fasciculus) benefit from facilitatory ipsilesional stimulation. Those with extensive left-hemisphere damage may require contralesional compensation. Recent meta-analyses indicate that repetitive transcranial magnetic stimulation (rTMS) combined with language therapy produces moderate improvements in naming and repetition (standardized mean difference (SMD) ≈ 0.7). Transcranial direct current stimulation (tDCS) shows small-to-moderate additive effects. Diffusion tensor imaging (DTI)-based assessment of white matter integrity is emerging as a key biomarker for treatment personalization. Conclusions: No universal recovery mechanism exists. Recovery involves molecular plasticity, structural remodeling, functional network reorganization, and experience-dependent adaptation. The bimodal balance–recovery model currently offers the most clinically useful framework. We recommend integrating neuroimaging biomarkers to guide personalized neuromodulation, combining either ipsilesional facilitation or contralesional compensation with intensive speech-language therapy. This framework is most directly applicable to chronic non-fluent and anomic aphasias; however, further validation is needed for patients with severe global aphasia.