defective corollary discharge model for verbal auditory hallucinations

   This is a term used to denote a variant of the "inner speech model for "verbal auditory hallucinations (VAH) that seeks to explain the misat-tribution of inner speech - which is deemed to underlie the mediation of (some types of) VAH or 'voices' - by reference to a default in corollary discharge. In this context the term corollary discharge refers to an early-warning signal (also known as feedforward signal or efference copy) purportedly sent by the speech production areas to the speech perception areas via the fronto-cingulo-temporal (FCT) circuit. The function attributed to this corollary discharge consists in 'preparing' the speech perception areas and/or the auditory cortex for an endogenous signal to come, thus allowing these structures to distinguish between self-mediated and externally mediated signals. As postulated by the British psychologist and neuroscientist Christopher Frith (b. 1942) and others, a failure in this type of corollary discharge can lead to the misattribution of inner speech to an external source. Conceptually, the defective corollary discharge model for hallucinations is a derivative of the CODAM model developed by the British mathematician John Gerald Taylor (b. 1931), which in turn constitutes an elaboration of the work of the American philosopher Sydney Shoemaker (b. 1931) on self-reference and self-awareness. CODAM is an acronym for COrollary Discharge of Attention Movement. The CODAM model postulates that the general deployment of attention, as well as the creation of consciousness, depend primarily on the ability of the brain (or mind) to predict its own future state, and that this ability is created by an efference copy or corollary discharge of the attention control signal.

   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., Frith, C.D. (1995). Abnormal monitoring of inner speech: A physiological basis for auditory hallucinations. Lancet, 346, 596-600.

   Shoemaker, S. (1968). Self-reference and self-awareness. Journal ofPhilosophy, 65, 555-567.

   Taylor, J.G., Rogers, M. (2002). A control model of the movement of attention. Neural Networks, 15, 309-326.