Tinnitus Intensity Dependent Gamma Oscillations of the Contralateral Auditory Cortex

Non-pulsatile tinnitus is considered a subjective auditory phantom phenomenon present in 10 to 15% of the population. Tinnitus as a phantom phenomenon is related to hyperactivity and reorganization of the auditory cortex. Magnetoencephalography studies demonstrate a correlation between gamma band activity in the contralateral auditory cortex and the presence of tinnitus. The present study aims to investigate the relation between objective gamma-band activity in the contralateral auditory cortex and subjective tinnitus loudness scores. In unilateral tinnitus patients (N = 15; 10 right, 5 left) source analysis of resting state electroencephalographic gamma band oscillations shows a strong positive correlation with Visual Analogue Scale loudness scores in the contralateral auditory cortex (max r = 0.73, p<0.05). Auditory phantom percepts thus show similar sound level dependent activation of the contralateral auditory cortex as observed in normal audition. In view of recent consciousness models and tinnitus network models these results suggest tinnitus loudness is coded by gamma band activity in the contralateral auditory cortex but might not, by itself, be responsible for tinnitus perception

Theta, alpha and beta burst transcranial magnetic stimulation: brain modulation in tinnitus

<p>Introduction: Some forms of tinnitus are considered to be auditory phantom phenomena related to reorganization and hyperactivity of the auditory central nervous system. Repetitive transcranial magnetic stimulation (rTMS) is a non-invasive tool capable of modulating human brain activity, using single pulse or burst stimuli. Burst rTMS has only been performed in the theta range, and has not been used clinically. The authors analyze whether burst TMS at theta (5 Hz), alpha (10 Hz) and beta (20 Hz) frequencies can temporarily suppress narrow band noise/white noise tinnitus, which has been demonstrated to be intractable to tonic stimulation.</p> <p>Methods: rTMS is performed both in tonic and burst mode in 46 patients contralateral to the tinnitus side, at 5, 10 and 20 Hz. Fourteen placebo negative rTMS responders are further analyzed.</p> <p>Results: In 5 patients, maximal tinnitus suppression is obtained with theta, in 2 with alpha and in 7 with beta burst stimulation. Burst rTMS suppresses narrow band/white tinnitus much better than tonic rTMS<i> t</i>(13)=6.4, <i>p</i>&#60;.000. Women experience greater suppression of their tinnitus with burst stimulation than men, <i>t</i>(12)=2.9, <i>p</i>&#60;.05. Furthermore left sided tinnitus is perceived as more distressing on the TQ than right sided tinnitus, <i>t</i>(12)=3.2, p&#60;.01. The lower the tinnitus pitch the more effectively rTMS suppresses tinnitus(<i>r</i>=-0.65, <i>p</i>&#60;0.05).</p> <p>Discussion: Burst rTMS can be used clinically, not only theta burst, but also alpha and beta burst. Burst rTMS is capable of suppressing narrow band/white noise tinnitus very much better than tonic rTMS. This could be due the simple fact that burst neuromodulation is more powerful than tonic neuromodulation or to a differential effect of burst and tonic stimulation on the lemniscal and extralemniscal auditory system. In some patients only alpha or beta burst rTMS is capable of suppressing tinnitus, and theta burst not. Therefore in future rTMS studies it could be worthwhile not to limit burst stimulation to theta burst rTMS.</p

Correlation between Independent Components of scalp EEG and intra-cranial EEG (iEEG) time series

International audience19 scalp electrode (EEG) and 8 intra-cranial electrode (iEEG) are recorded simultaneously with a common reference. EEG data is subjected to independent component analysis (ICA) and localisation of components in grey matter is estimated by the sLORETA inverse solution. Correlation between the time series of two independent components and intra-cranial recordings is very high (computed over 23552 samples, max r = 0.8 and 0.67, respectively). One component is localized underneath the site of the implanted electrode. These findings were replicated using the second row of 8 iEEGs and an independent 19-electrode EEG recording, validating the source localisation provided by combining ICA and sLORETA