Esplorazione delle intersezioni tra Denominazione e Discorso nella PPA: correlati cognitivi e neurali

Picture naming and connected speech are among the most informative language tasks for diagnosing Primary Progressive Aphasia (PPA), as they provide relevant insights into several linguistic domains. While both tasks can reveal similar error types, such as semantic errors, others, like information units, are specific to connected speech. Understanding the overlap and divergence between these tasks is crucial for both clinical assessment and theoretical models of language breakdown in PPA. This study examines the relationship between naming and connected speech, focusing on shared and task-specific features as well as their neural correlates. Forty-eight individuals with PPA (10 semantic, 23 logopenic, 5 nonfluent/agrammatic, 10 mixed) completed picture-naming tasks from the CaGi and SAND batteries, and the picture description task from the SAND. Brain metabolism was assessed using an FDG-PET scan. Correlations between naming accuracy, error types (semantic, phonological, anomia), connected speech features (e.g., information units, noun ration, total number of utterances) and metabolism extracted from 10 Regions of Interest were assessed. Naming accuracy in both tasks positively correlated with the number of information units and lexico-semantic errors produced. Neuroimaging results showed that both naming accuracy and semantic errors were linked to reduced metabolism in the anterior fusiform gyrus and temporal pole. Additional associations emerged between specific error types and posterior temporal regions. These findings highlight both shared and distinct cognitive and neural mechanisms underlying naming and connected speech in PPA. The correlation between naming performance and discourse informativeness supports a common lexico-semantic basis rooted in anterior temporal regions. Integrating both tasks may enhance clinical profiling and advance our understanding of language processing in neurodegenerative conditions. Keywords: Primary Progressive Aphasia, Connected Speech, Naming, Language assessment, FDG-PET.