Right-lateralized neural activity during inner speech repeated by cues

Abstract

Neural activity during inner speech of meaningless syllable sequences was measured with MEG and fMRI from eight right-handed subjects who executed a delayed-response task. An fMRI-constrained MEG multi-dipole analysis showed that active neural sources were detected at latencies of about 200-300 ms after cues near the posterior superior temporal sulcus and were more numerous in the right hemisphere than in the left hemisphere. Since the subjects were cued to repeat inner speech of meaningless sequences stored in verbal working memory, the activity in the right (language-nondominant) hemisphere suggested that the task required processing of more prosodic features such as pitch and rhythm than phonemic features.