Quantitative resting EEG analysis of chronic tinnitus in the context of thalamocortical dysrhythmia
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1
University Hospital Zürich, Switzerland
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2
Brain Dynamics and Cognition Lab, INSERM, France
By definition tinnitus is an auditory perception of sound in the absence of an external auditory stimulus. Neurophysiological mechanisms underlying tinnitus perception are not fully understood yet.
Oscillatory EEG activity is increasingly recognized as a fundamental hallmark of cortical integrative functions. We aimed to study deviations from the norm of different resting EEG parameters in tinnitus patients.
To study the neurophysiological mechanisms of chronic therapy-resistant tinnitus, we recorded spontaneous EEG (64 channels) from 9 patients and 16 healthy, age-matched controls, while subjects had their eyes closed. Artefacts were removed using independent component analysis (ICA) and spectra were estimated by multitaper FFT. The spectra were divided into the frequency bands delta (2-4 Hz), theta (4-8 Hz), alpha (8-12 Hz), low beta (12-18 Hz), high beta (18-30) and gamma (30-100). On average, the patient group exhibited higher spectral power over the frequency range of 2-25 Hz. Maximal differences appeared in the 4-8 Hz theta band in centrofrontotemporal electrodes. In addition we calculated power spectra in a frontal, central and parietal region of interest (ROI) over the frequency range of 2-100 Hz. Only in the frontal ROI did patients show a trend of power increase in beta and gamma bands. The mean of theta band power, in tinnitus patients as compared with healthy controls, was significantly increased at p<0.05 after false discovery rate (FDR) correction for multiple comparisons. In addition, electrode-wise comparisons of power between the patient and control groups showed highest z-values in frontocentrotemporal electrodes in the theta band and in frontocentral electrodes between 14 and 25 Hz. Cortical generators of increased theta neuronal activities using LORETA were localized in superior and middle temporal gyrus, and in temporopolar, prefrontal lateral, orbitofrontal lateral and insular areas.
These EEG findings add to the microphysiological and magnetoencephalographic evidence for a thalamocortical dysrhythmic process at the source of tinnitus, characterised by a low frequency overproduction in thalamocortical loops. These results could have important implications for the treatment of tinnitus by selective regulatory interventions on the thalamocortical network.
Conference:
Neuroinformatics 2008, Stockholm, Sweden, 7 Sep - 9 Sep, 2008.
Presentation Type:
Poster Presentation
Topic:
Electrophysiology
Citation:
Moazami-Goudarzi
M,
Michels
L,
Weisz
N and
Jeanmonod
D
(2008). Quantitative resting EEG analysis of chronic tinnitus in the context of thalamocortical dysrhythmia.
Front. Neuroinform.
Conference Abstract:
Neuroinformatics 2008.
doi: 10.3389/conf.neuro.11.2008.01.098
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Received:
28 Jul 2008;
Published Online:
28 Jul 2008.
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Correspondence:
Morteza Moazami-Goudarzi, University Hospital Zürich, Zürich, Switzerland, morteza.moazami@gmail.com