inner speech model for verbal auditory hallucinations

   Also known as misattribution model for verbal auditory hallucinations. The two names are used interchangeably to denote a hypothetical model attributing the mediation of some types of "verbal auditory hallucination (VAH) to a disorder of " inner speech. The inner speech model suggests that individuals experiencing VAH are unaware of their own verbal thoughts and that they may subsequently misattribute these to an external source. Traditionally, the inner speech model comes in two variants. These are referred to as the " input model (which attributes the mediation of VAH to disinhibited neuronal activity within "Wernicke's speech reception area) and the "output model (which seeks to explain the mediation of VAH by reference to disinhibited neuronal activity within Broca's speech production area). A third variant of the inner speech model, which seeks to explain the misattribution of inner speech to a default in the corollary discharge from the frontal speech production areas towards the speech perception areas, is known as the "defective corollary discharge model for hallucinations. Conceptually, the inner speech model for VAH constitutes an elaboration of the "bicameral mind theory of the American psychologist Julian Jaynes (19201997). Jaynes's theory relates the 'voices' heard by individuals in ancient cultures to the purported presence of two virtual rooms or chambers within their minds, one of which is envisaged as being involved in the mediation of verbal thoughts and the other as being involved in their reception. According to Jaynes, having a bicameral mind used to lead to the individual's perception of endogenously mediated verbal thoughts, although he was not capable of determining their endogenous origin. The inner speech model has served as the principal conceptual framework for many of the neuropsychological and imaging studies of VAH carried out from the 1980s onwards. Although these studies have succeeded in corroborating the role of the speech centres in the mediation of VAH, a number of conceptual and empirical issues have yet to be addressed. In the version outlined above, the inner speech model would seem to be suitable as an explanatory model for the mediation of thought insertion, thought intrusion, and even "psychomotor verbal hallucinations, which are conceptualized as being inaudible in nature. As inner speech is conceptualized as a cognitive rather than a perceptual phenomenon, and most versions of the inner speech model leave the role of the primary auditory cortex out of the equation, it is as yet unclear how inner speech - whether it originates from Broca's area or not - might be converted into a perceptual phenomenon such as a VAH. (A hypothetical model designed to explain this conversion is known as the "perceptualization of the concept.) If it were possible to settle this issue to universal satisfaction, the inner speech model might also serve as an explanatory model for the mediation of " Gedankenlautwerden.But it would still be something of a challenge to imagine how inner speech might contribute to the mediation of other types of VAH, which are generally perceived as spoken in the voice of a third person, or how they might contribute to the mediation of various voices speaking simultaneously or a voice speaking in a foreign language not mastered by the affected individual. Given the fact that inner speech was originally conceptualized by Vygotsky as a psychological interface between culturally sanctioned symbolic systems (such as natural languages) and one's own private thought, it is not easy to envisage its role in the mediation of VAH consisting of 'foreign' voices. Thus it would seem that inner speech models for verbal auditory hallucinations tend to be based only loosely on Vygotsky's original notion of inner speech. Instead, they would seem to go back to a slightly broader notion, introduced in 1958 by the American psychiatrist and psychoanalyst Arnold H. Modell (b.1924) and referred to as " hallucinated inner speech. Modell envisages the notion of hallucinated inner speech as a type of inner speech involving not only the ego's verbal thoughts but also the verbal utterances of internalized objects. In Modell's own words, "The voices are identified as formerly loved persons, principally the parents, who in some unexplained way are fused to the self. These voice objects function as parents in terms of giving advice and being a source of prohibitions, and also in gratifying wishes stemming from all stages of infantile development." For a comparison of the respective notions formulated by Vygotsky and Modell, see the entries Inner speech and Hallucinated inner speech.

   References

   Ford, J.M., Mathalon, D.H., Heinks, T., Kalba, S., Faustman, W.O., Roth, W.T. (2001). Neu-rophysiological evidence of corollary discharge dysfunction in schizophrenia. American Journal of Psychiatry, 158,2069-2071. McGuire, P.K., Silbersweig, D.A., Wright, I., Murray, R.M., David, A.S., Frackowiak, R.S.J., Frith, C.D. (1995). Abnormal monitoring of inner speech: A physiological basis for auditory hallucinations. Lancet, 346, 596-600.

   Mechelli, A., Allen, P., Amaro, E., Fu, C.H., Williams, S.C., Brammer, M.J., Johns, L.C., McGuire, P.K. (2007). Misattribution of speech and impaired connectivity in patients with auditory verbal hallucinations. Human Brain Mapping, 28, 1213-1222. Modell, A.H. (1958). The theoretical implications of hallucinatory experiences in schizophrenia. Journal ofthe American Psychoanalytical Society, 6, 442-480.