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Original Research ARTICLE

Front. Hum. Neurosci., 28 March 2008 | http://dx.doi.org/10.3389/neuro.09.006.2007

Auditory hallucinations in schizophrenia: the role of cognitive, brain structural and genetic disturbances in the left temporal lobe

1
Department of Biological and Medical Psychology, University of Bergen, Bergen, Norway
2
Division of Psychiatry, Helse-Bergen HF, Bergen, Norway
3
Department of Clinical Engineering, Haukeland University Hospital, Bergen, Norway
4
Department of Clinical Medicine/Bergen Mental Health Research Center, University of Bergen, Bergen, Norway
5
Center for Medical Genetics and Molecular Medicine, Haukeland University Hospital, Bergen, Norway
In this article we review research in our laboratory on auditory hallucinations using behavioral and MRI measure. The review consists of both previously published and new data that for the first time is presented together in a cohesive way. Auditory hallucinations are among the most common symptoms in schizophrenia, affecting more than 70% of the patients. We here advance the hypothesis that auditory hallucinations are internally generated speech perceptions that are lateralized to the left temporal lobe, in the peri-Sylvian region. From this we predict that hallucinating patients should have problems identifying a simultaneously presented external speech sound, as measured through performance on the dichotic listening (DL) paradigm with consonant – vowel syllables, since this technique lateralizes the stimulus input. Across a series of behavioral experiments, we have shown that patients with schizophrenia who experience frequent auditory hallucinations fail to demonstrate an expected right ear advantage on the dichotic listening test. Absence of a right ear advantage is indicative of a functional deficit in the left peri-Sylvian region. The results also revealed that patients with ongoing auditory hallucinations were more impaired than patients with previous hallucinations, and that a higher score on the hallucination item in a standard symptom rating scale (BPRS) correlated negatively with number of correct reports for the right ear stimulus. Moreover, we have found that schizophrenia patients fail to shift attention to the left ear stimulus, when explicitly instructed to focus on the right or left ear stimulus only, thus showing a deficit in inhibition of attention and response-inhibition. The behavioral DL data are substantiated in two MR morphometry studies that revealed significant reductions in grey matter density in the left peri-Sylvian region in hallucinating patients, and patients with reduced left temporal lobe grey matter density. Hallucinating patients also failed to show a right ear advantage in the dichotic listening test. Ongoing fMRI studies are focused on the underlying synaptic and molecular mechanisms by investigating the effects of the glutamate antagonist drug memantine on auditory perception and speech lateralization, and examination of temporal cortex-specific gene expression in the left peri-Sylvian region.
Keywords:
auditory hallucinations, schizophrenia, hemisphere asymmetry, dichotic listening, memantine, fMRI, VBM
Citation:
Hugdahl K, Løberg E-M, Specht K, Steen VM, van Wageningen H and Jørgensen HA (2008). Auditory hallucinations in schizophrenia: the role of cognitive, brain structural and genetic disturbances in the left temporal lobe. Front. Hum. Neurosci. 1:6. doi: 10.3389/neuro.09.006.2007
Received:
16 September 2007;
 Paper pending published:
29 November 2007;
Accepted:
03 January 2008;
 Published online:
28 March 2008.

Edited by:

Robert T. Knight, University of California Berkeley, USA

Reviewed by:

Patrik Vuilleumier, University Medical Center and University Hospital Geneva, Switzerland
Anna C. Nobre, University of Oxford, UK
Copyright:
© 2008 Hugdahl, Løberg, Specht, Steen, Wageningen and Jørgensen. This is an open-access article subject to an exclusive license agreement between the authors and the Frontiers Research Foundation, which permits unrestricted use, distribution, and reproduction in any medium, provided the original authors and source are credited.
*Correspondence:
Kenneth Hugdahl, Department of Biological and Medical Psychology/Bergen Mental Health Research Center, University of Bergen, Jonas Lies vei 91, N 5009 Bergen, Norway. e-mail: hugdahl@psybp.uib.no