Phonation, emotion, cognition, with reference to the brain mechanisms involved

Phylogenetic steps in the evolution of vocal communication have a bearing on the brain mechanisms involved in the emergence of human language and speech. A schema of the neuronal organization of voicing in a hierarchical manner is presented. At the lowest mesencephalic level the movements of the vocal apparatus are coordinated and integrated into species-specific vocal gestures. At the middle level these signals are controlled by the anterior limbic cortex, which serves this function in primates only, and only in the human species is the highest level around the cortical larynx and facial area actively involved in the vocal signalling process. This functional schema is used to explain the sequential stages in the ontogenetic process of phonemicization in the human infant, and special emphasis is placed on vocal-auditory feedback mechanisms which come into play from the lowest to the highest level of the central nervous system during maturation. Even feedback loops of the lowest level enable the distinction to be made between self-produced vocalizations and those produced by others. These mechanisms are thought to be an early means for the development of self-awareness. If one grants that the human infant possesses self-awareness, one must concede that such stages of the mind were developed before the emergence of the human species.