Naturalistic language assessment and brain-network biomarkers in post-stroke aphasia for precision neurorehabilitation

Advances in naturalistic language assessment, portable neuroimaging, electrophysiology, and brain-network modeling are creating new opportunities to evaluate post-stroke aphasia under conditions closer to real-world communication. Conventional aphasia batteries and isolated linguistic tasks remain essential for diagnosis, severity classification, and treatment planning, but they provide limited information about how language-network activity supports communication in dynamic, naturalistic contexts. This integrative review, informed by a structured literature search and descriptive thematic mapping, synthesizes evidence on connected speech, discourse production, narrative comprehension, interactive communication, and contextual reading after stroke. We examine how multilevel features from these behaviors can be organized into graded, interacting dimensions of lexical-semantic access, phonological encoding, grammatical organization, discourse processing, executive-predictive control, and speech-motor output. We further review multimodal evidence from fNIRS, fMRI, EEG/ERP, lesion-symptom mapping, structural connectivity, and functional connectivity, highlighting residual left-hemisphere language networks, conditional right-hemisphere support, bilateral reorganization, domain-general control systems, and longitudinal recovery. Portable EEG and fNIRS are considered complementary approaches for repeated assessment during less constrained language tasks, with distinct temporal, spatial, and practical trade-offs. Building on this evidence, we propose an operational ecological biomarker framework that links task choice, multilevel feature extraction, multivariate behavioral profiles, neural measures, prespecified clinical questions, and longitudinal outcomes. This framework may support recovery prediction, rehabilitation stratification, neuromodulation target selection, individualized therapy planning, and monitoring of functional communication.