from Part III - Disturbances of the self: the case of schizophrenia
Published online by Cambridge University Press: 18 December 2009
Abstract
In this chapter we attempt to explain one class of symptoms associated with schizophrenia. We concentrate on symptoms that are characterized by a confusion between the self and other, such as auditory hallucinations and delusions of control. We propose that such symptoms arise because of a failure in the mechanism by which the predicted consequences of self-produced actions are derived from an internal forward model. Normally the forward model predicts and cancels the sensory consequences of self-produced actions. We argue that an impairment in this prediction and cancellation mechanism can cause self-produced sensations to be classified as externally produced. This problem leads to a number of behavioural consequences, such as a lack of central error correction, many of which have been observed in patients with delusions of control and related symptoms. At the physiological level, delusions of control are associated with overactivity in the parietal cortex. We suggest that this overactivity results from a failure to attenuate responses to sensations of limb movements even though these sensations can be anticipated on the basis of the movements intended. The lack of attenuation may arise from corticocortical disconnections which prevent inhibitory signals arising in the frontal areas which generate motor commands from reaching the appropriate sensory areas.
Introduction
Auditory hallucinations and passivity symptoms in schizophrenia
Rather than attempting to elucidate a biological basis for schizophrenia, our aim in this chapter is to try and explain one class of symptoms.
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