Studying auditory verbal hallucinations using the RDoC framework

Abstract

In this paper, I explain why I adopted a Research Domain Criteria (RDoC) approach to study the neurobiology of auditory verbal hallucinations (AVH), or voices. I explain that the RDoC construct of "agency" fits well with AVH phenomenology. To the extent that voices sound nonself, voice hearers lack a sense of agency over the voices. Using a vocalization paradigm like those used with nonhuman primates to study mechanisms subserving the sense of agency, we find that the auditory N1 ERP is suppressed during vocalization, that EEG synchrony preceding speech onset is related to N1 suppression, and that both are reduced in patients with schizophrenia. Reduced cortical suppression is also seen across multiple psychotic disorders and in clinically high-risk youth, but it is not related to AVH. The motor activity preceding talking and connectivity between frontal and temporal lobes during talking have both proved sensitive to AVH, suggesting neural activity and connectivity associated with intentions to act may be a better way to study agency and predictions based on agency.

Keywords: Agency; Auditory verbal hallucinations; EEG; ERP; N1; RDoC.

Figure 1

The intention to say “ah” during the Talk condition is represented as a thought bubble in the speech production areas of the frontal lobe. A command is sent to pre-motor and motor cortical areas, shown with a dotted bi-directional line. In motor cortical areas, two commands are issued: One is the primary command to initiate the motor act of speaking, and one is an efference copy of that command which is sent to auditory cortex. In auditory cortex, a corollary discharge of the expected “ah” sound is generated. This is represented as a red burst, overlaid with “ah” in the cartoon. An auditory re-afference is produced by the vocalized speech and represented as an “ah” entering the ear. The neural representation of the sensation in auditory cortex is shown as a green burst. When auditory re-afference (what you hear) matches the corollary discharge (what you intended to say), auditory cortical responsiveness is suppressed.

Figure 2

During the Listen condition, the speech sounds the subject vocalized during the Talk condition are played to the subject who passively listens to them.