A voice without a mouth no more: The neurobiology of language and consciousness.

Language, especially inner speech, is hypothesized to generate and sustain higher-order self-awareness. A 'HOLISTIC' model proposes a core set of inner speech production regions that initiate the experience of feeling and hearing words, which acquire affective qualities through activation of associated sensory, motor, and emotional representations in a largely unconscious dynamic periphery distributed throughout the brain. Responding to these words sustains network activity involving default mode activation and prefrontal and thalamic/brainstem selection of contextually relevant responses. The model offers a more parsimonious account of the neural correlates of consciousness and has implications for mental health and wellbeing.

Study at a glance

Abstract

Most research on the neurobiology of language ignores consciousness and vice versa. Here, language, with an emphasis on inner speech, is hypothesised to generate and sustain self-awareness, i.e., higher-order consciousness. Converging evidence supporting this hypothesis is reviewed. To account for these findings, a 'HOLISTIC' model of neurobiology of language, inner speech, and consciousness is proposed. It involves a 'core' set of inner speech production regions that initiate the experience of feeling and hearing words. These take on affective qualities, deriving from activation of associated sensory, motor, and emotional representations, involving a largely unconscious dynamic 'periphery', distributed throughout the whole brain. Responding to those words forms the basis for sustained network activity, involving 'default mode' activation and prefrontal and thalamic/brainstem selection of contextually relevant responses. Evidence for the model is reviewed, supporting neuroimaging meta-analyses conducted, and comparisons with other theories of consciousness made. The HOLISTIC model constitutes a more parsimonious and complete account of the 'neural correlates of consciousness' that has implications for a mechanistic account of mental health and wellbeing.