Inner speech and external speech: phonemes, syllables and words. fMRI study

Procedia Computer Science. 2022. Vol. 213. P. 136–143.

Shevchenko A., Suyuncheva A., Vartanov A., Bronov O.

This article describes the fMRI study of the processes of internal and external speech. The purpose of this work is to compare the processes of internal and external speech in conjunction with those activated structures. The experiment included 3 series for each type of stimulus (words, syllables, phonemes): simple listening to stimulus material, listening followed by internal pronunciation, and listening followed by pronunciation aloud. The study involved 33 respondents (10 men and 23 women ranging from 20 to 30 years old, mean age = 24 years). The results of study is connected with the identification of zones specifically associated with inner speech. Areas such as BA37, BA38, and cerebellar areas were found to be associated with the type of pronunciation, external or internal. A significant activation of the vACC zone (BA24) was found during external speech, in contrast to inner speech, which is most likely associated with a complex function of social reinforcement of this zone.

Keywords: localization, inner speech, subvocalization, speech MRI