Mechanisms of auditory verbal hallucination in schizophrenia

Abstract

Recent work on the mechanisms underlying auditory verbal hallucination (AVH) has been heavily informed by self-monitoring accounts that postulate defects in an internal monitoring mechanism as the basis of AVH. A more neglected alternative is an account focusing on defects in auditory processing, namely a spontaneous activation account of auditory activity underlying AVH. Science is often aided by putting theories in competition. Accordingly, a discussion that systematically contrasts the two models of AVH can generate sharper questions that will lead to new avenues of investigation. In this paper, we provide such a theoretical discussion of the two models, drawing strong contrasts between them. We identify a set of challenges for the self-monitoring account and argue that the spontaneous activation account has much in favor of it and should be the default account. Our theoretical overview leads to new questions and issues regarding the explanation of AVH as a subjective phenomenon and its neural basis. Accordingly, we suggest a set of experimental strategies to dissect the underlying mechanisms of AVH in light of the two competing models. We shall contrast two proposed mechanisms of auditory verbal hallucinations (AVH): (a) the family of self-monitoring accounts and (b) a less discussed spontaneous activity account. On the former, a monitoring mechanism tracks whether internal episodes such as inner speech are self- or externally generated while on the latter, spontaneous auditory activity is the primary basis of AVH. In one sense, self-monitoring accounts emphasize "top-down" control mechanisms; spontaneous activity accounts emphasize "bottom-up" sensory mechanisms. The aim of this paper is not to provide a comprehensive literature review on AVH as there have been recent reviews (1, 2). Rather, we believe that it remains an open question what mechanisms underlie AVH in schizophrenia, and that by drawing clear contrasts between alternative models, we can identify experimental directions to explain what causes AVH. Self-monitoring accounts have provided much impetus to current theorizing about AVH, but one salient aspect of our discussion is to raise questions as to whether such accounts, as currently formulated, can adequately explain AVH. We believe that there are in fact significant limitations to the account that have largely gone unnoticed. Still, both models we consider might hold, and this requires further empirical investigation. Conceptual and logical analysis, however, will play an important role in aiding empirical work. © 2013 Cho and Wu.