Synch Before You Speak: Auditory Hallucinations in Schizophrenia

Stanford University, Palo Alto, California, United States
American Journal of Psychiatry (Impact Factor: 12.3). 04/2007; 164(3):458-66. DOI: 10.1176/appi.ajp.164.3.458
Source: PubMed


Synchronization of neural activity preceding self-generated actions may reflect the operation of the forward model, which acts to dampen sensations resulting from those actions. If this is true, pre-action synchrony should be related to subsequent sensory suppression. Deficits in this mechanism may be characteristic of schizophrenia and related to positive symptoms, such as auditory hallucinations. If so, schizophrenia patients should have reduced neural synchrony preceding movements, especially patients with severe hallucinations.
In 24 patients with schizophrenia or schizoaffective disorder and 25 healthy comparison subjects, the authors related prespeech neural synchrony to subsequent auditory cortical responsiveness to the spoken sound, compared prespeech neural synchrony in schizophrenia patients and healthy comparison subjects, and related prespeech neural synchrony to auditory hallucination severity in patients. To assess neural synchrony, phase coherence of single-trial EEG preceding talking was calculated at a single site across repeated trials. To assess auditory cortical suppression, the N1 event-related brain potentials to speech sound onset during talking and listening were compared.
In healthy comparison subjects, prespeech neural synchrony was related to subsequent suppression of responsiveness to the spoken sound, as reflected in reduction of N1 during talking relative to listening. There was greater prespeech synchrony in comparison subjects than in patients, especially those with severe auditory hallucinations.
These data suggest that EEG synchrony preceding speech reflects the action of a forward model system, which dampens auditory responsiveness to self-generated speech and is deficient in patients who hallucinate.

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Available from: Daniel H Mathalon
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    • "They have been related to several brain functions, such as perception, attention, memory, consciousness and synaptic plasticity (Uhlhaas et al 2008). In agreement with previous studies, our findings suggest that SCH patients decrease their γ-coupling activity between response and baseline (Slewa-Younan et al 2004), whereas controls exhibit a γ-coupling increase (Ford et al 2007). Abnormal γ-band activity has also been related to disturbed corollary modulation of sensory processes (Uhlhaas et al 2008). "
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    • "Functional neural networks, such as the language processing network, are mostly investigated using two different approaches: (1) through assessment of activity patterns during experimental tasks (Meyer-Lindenberg et al., 2001; Lawrie et al., 2002; Calhoun et al., 2004; Ford et al., 2007; Garrity et al., 2007) or (2) through restingstate functional imaging (e.g. resting-state fMRI). "
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    • "A primary aim of this research was to test the predictions of the comparator account as it applied to misattributed inner speech. Overall, the results have been interpreted as suggesting that inner speech is normally attenuated, and that there is a failure of attenuation of inner speech in patients with a diagnosis of schizophrenia (Ford et al., 2001a,b,c, 2007; Ford and Mathalon, 2004, 2005, 2012; Heinks-Maldonado et al., 2007). As such, the results appear to provide key evidence in favor of the current comparator account of misattributed inner speech. "
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