Análise eletrofisiológica do reconhecimento facial após o acidente vascular encefálico: um estudo com o protocolo de estimulação visual periódica rápida

Abstract

This thesis investigated the neurophysiological markers of facial processing in healthy elderly individuals and post-Cerebrovascular Accident (CVA) patients. The central objective was to

validate the applicability and sensitivity of the Fast Periodic Visual Stimulation (FPVS- Oddball) protocol coupled with EEG as an assessment tool. The methodology, structured

across three studies, utilized the FPVS-Oddball paradigm to compare young adults, healthy elderly individuals, and post-CVA patients (with right-hemisphere (RH) or left-hemisphere (LH) lesions) in tasks involving recognition (face vs. object), facial identity discrimination, and discrimination of facial emotional expressions (joy/anger vs. neutral). The protocol is based on measuring neural synchronization at a base frequency (e.g., 6 Hz) to evaluate general visual processing, and at an Oddball frequency (e.g., 1.2 Hz) to assess specific high-order discrimination. Neurophysiological findings indicated that while healthy aging modulates this capacity, CVA induces a pronounced deficit. The results revealed a functional dissociation: whereas low-level visual processing (base frequency) was preserved in the clinical group, a drastic reduction or absence of the specific neural response (Oddball) for discriminating identities and emotions was observed. This impairment was significantly more pronounced in patients with RH lesions, corroborating the dominance of this hemisphere for complex facial functions. It is concluded that the FPVS-Oddball constitutes an objective, rapid, and sensitive tool with high potential for diagnosing and monitoring deficits in social cognition within clinical populations.