Self awareness and speech processing: an fMRI study.

Language production and perception imply motor system recruitment. Therefore, language should obey the theory of shared motor representation between self and other, by means of mirror-like systems. These mirror-like systems (referring to single-unit recordings in animals) show the property to be recruited both when accomplishing and when perceiving a goal-directed action, whatever the sensory modality may be. This hypothesis supposes that a neural network for self-awareness is involved to distinguish speech production from speech listening. We used fMRI to test this assumption in 12 healthy subjects, who performed two different block-design experiments. The first experiment showed involvement of a lateral mirror-like network in speech listening, including ventral premotor cortex, superior temporal sulcus and the inferior parietal lobule (IPL). The activity of this mirror-like network is associated with the perception of an intelligible speech. The second experiment looked at a self-awareness network. It showed involvement of a medial resting-state network, including the medial parietal and medial prefrontal cortices, during the 'self-generated voice' condition, as opposed to passive speech listening. Our results support the fact that deactivation of this medial network, in association with modulation of the activity of the IPL (part of the mirror-like network previously described), is linked to self-awareness in speech processing. Overall, these results support the idea that self-awareness is present when distinguishing between speech production and speech listening situations, and may depend on these two different parieto-frontal networks.