Functional Neuroanatomy of Human Vocalization: An H215O PET Study

Abstract

Vocalization in lower animals is associated with a well-described visceromotor call system centered on the mesencephalic periacqueductal grey matter (PAG), which is itself regulated by paramedian cortical structures. To determine the role this phylogenetically older system plays in human phonation, we contrasted voiced and unvoiced speech using positron emission tomography and then evaluated functional connectivity of regions that significantly differentiated these conditions. Vocalization was associated with increased and highly correlated activity within the midline structures--PAG and paramedian cortices--described in lower mammalian species. Concurrent activation and connectivity of neocortical and subcortical motor regions--medial and lateral premotor structures and elements of basal ganglia thalamocortical circuitry--suggest a mechanism by which this system may have come under an increasing degree of voluntary control in humans. Additionally, areas in the temporal lobe and cerebellum were selectively activated during voiced but not unvoiced speech. These regions are functionally coupled to both visceromotor and neocortical motor areas during production of voiced speech, suggesting they may play a central role in self-monitoring and feedback regulation of human phonation.

Respiratory, postural and spatio-kinetic motor stabilization, internal models, top-down timed motor coordination and expanded cerebello-cerebral circuitry: a review

“…Like them, this is consistent with them being linked to the cerebello-cerebral cortex circuits (Callan et al, 2007;Callan et al, 2006;Dresel et al, 2005;Loucks et al, 2007;Murphy et al, 1997;Schulz et al, 2005;Spencer and Slocomb, 2007). Further, like dexterity and bipedality, the kinematics of speech production continues to be refined into adolescence and after (Smith and Zelaznik, 2004).…”

Neural circuits underlying crying and cry responding in mammals

“…However, in adults, a PET study found that during voiced speech (which shares some laryngeal control mechanisms with crying), blood flow increased in the PAG, as well as the cerebellar vermis and parts of the thalamus [103]. This study also found activation in cortical regions (see below).…”

“…However, given the likelihood that similar laryngeal action is involved in both crying and production of voiced sounds in adults, a PET study describing cortical activation during production of voiced speech is of interest. Shulz, et al [103] found significant elevation of regional blood flow in the inferior operculum of the prefrontal gyrus, the medial prefrontal cortex and the anterior cingulate cortex in voiced but not during whispered speech.…”

Task-specific change of unconscious neural priming in the cerebral language network

“…Another recent study has further shown a functional coupling between auditory and motor areas during vocalization (31). The premotor and inferior parietal cortices, also involved in speech production, exhibit increased connectivity during speech perception (32).…”