Language-related glossokinetic potentials on scalp

Glossokinetic potential (GKP) is the potential response generated from tongue movements. The tongue is one of main articulators determining the sound of spoken language, and tongue-oriented GKP can severely interfere electroencephalography (EEG) signals involved in language-related tasks. To clarify the relation between GKP and language, and provide information such that what kinds of phonemes evoke GKP response and where the response can be observed, we investigate GKP responses from various phonemes. In detail, we record EEG signals when the tongue touches each place of articulation (the reference points used for the categorization of consonants in phonetics), then analyze their spatial and scale patterns. The results showed pronouncing dental, palato-alveolar, and palatal consonants evokes potential decrease in the frontal region, and potential increase in the occipital region. On the other hand, pronouncing retroflex consonant evokes potential increase in the frontal region, and decrease in the occipital region. We believe that the surveyed GKP patterns will be useful for developing artifact removal techniques eliminating language-related artifacts. The GKP removal could be beneficial for neuroscience in language processing, implementing brain-computer interface in real-world condition, and developing a novel silent speech recognition technique.