Functional Mapping of Inner Speech Areas: A Preliminary Study with Portuguese Speakers

• Published in: Speech and Computer Vol. 11096; pp. 166 - 176
• Main Authors: Ferreira, Carlos, Direito, Bruno, Sayal, Alexandre, Simões, Marco, Cadório, Inês, Martins, Paula, Lousada, Marisa, Figueiredo, Daniela, Castelo-Branco, Miguel, Teixeira, António
• Format: Book Chapter
• Language: English
• Published: Switzerland Springer International Publishing AG 2018; Springer International Publishing
• Series: Lecture Notes in Computer Science
• Subjects: First keyword; fMRI; Inner speech portuguese; Overt speech; Portuguese
• ISBN: 3319995782; 9783319995786
• ISSN: 0302-9743; 1611-3349
• DOI: 10.1007/978-3-319-99579-3_18

Inner speech can be defined as the act of talking silently with ourselves. Several studies aimed to understand how this process is related to speech organization and language. Despite the advances, some results are still contradictory. Importantly, language dependency is scarcely studied. For this first study of inner speech for Portuguese native speakers using fMRI, we selected a confrontation naming task, consisting of 40 black and white line drawings. Five healthy participants were instructed to name in inner and in overt speech the visually presented image. fMRI data analysis considering the proposed inner speech paradigm identified several brain areas such as the left inferior frontal gyrus, including Broca’s area, supplementary motor area, precentral gyrus and left middle temporal gyrus including Wernicke’s area. Our results also show more pronounced bilateral activations during the overt speech task when compared to inner speech, suggesting that inner and overt speech activate similar areas but stronger activation can be found in the later. However, this difference stems in particular from significant activation differences in the right pre-central gyrus and middle temporal gyrus.