Lost in Thought: An End-to-End Systematic Review on Imagined Speech Decoding Through Electroencephalographic Readings

Many fields, including psychology, neuroscience, linguistics, computational modeling, and even philosophy, have been investigating the neuroscience of language for many years. Even so, a lack of comprehensive, interdisciplinary guidelines remains for research projects that aim to decode or model language from brain activity. Electroencephalography (EEG) is unique among neuroimaging methods in that it is a non-invasive technique. This review provides a comprehensive examination of the fundamental elements of imagined speech decoding using EEG, offering a tour of the most recent developments and perspectives in linguistic, neurological, and computational approaches over the past decade. It highlights essential findings such as the consistent involvement of sensory–motor brain regions, the strong influence of language abstraction and selection, and the superior classification performance attained with spectral and temporal features. This study was conducted and reported in accordance with the PRISMA 2020 guidelines for systematic reviews.