Physiological Regulation of Chronic Tinnitus
Otolaryngology, Phoniatrics and Audiology
Final Report Abstract
The methodology and the results of this project show that with a rigorous methodology which fulfills the major criteria of a specific learning treatment of chronic tinnitus namely on-line feedback of inhibitory alpha activity from the auditory cortex – never achieved in the previous literature – the three main scientific questions asked in this project (see above) do not allow positive answers. Instead, a more differentiated and more complex picture emerge. First, neurofeedback training exerts a strong positive effect on the tinnitus symptoms and reduce suffering in most patients with very severe tinnitus. However, this effect is not a consequence of the physiological changes and the proposed learned strengthening of neural inhibition at the source of the phantom noise in the auditory cortex induced by localized alpha neurofeedback but an unspecific psychological consequence probably of positive expectancy and the reduction of cognitive dissonance related to the cognitive attribution of concentration and effort (“placebo”) invested in the 15 sessions of training. Only a few patients, independent of the severity of the symptoms and independent of accompanying psychological disorders such as depression and anxiety learn to control and increase auditory alpha activity: Different reasons could be responsible for this lack of covariation between neurophysiology and behavior: 1) training time too short for automatization of alpha increase in the real environment (generalization) of the patients and/or permanent neuronal reorganization of the auditory structures after the many years of tinnitus unresponsive to a non-invasive training procedure. 2) Auditory alpha is not causally determined by the underlying cortical reorganization responsible for the symptoms and thus, learned changes of alpha have no effect on these unrelated processes. If this is true, the previous scientific history and experimentation finding reduction of auditory alpha in tinnitus is not correct or too variable to be replicated. Even if these “destructive” hypotheses and explanations are correct, the methodology for on-line neurofeedback of localized alpha developed for this project now allows systematic replication and variation of the determining variables of neurofeedback training in tinnitus in future larger clinical trials and may be used also for other disease states (i.e. drug resistant epilepsy, sleep disorders, chronic pain, dyslexia, dystonia), all characterized by anatomically localized dysfunctions of cortical networks. On the productive side, our results strengthen a physiological origin of tinnitus and do not support a causal relationship between psychological factors (“stress”) and tinnitus. Rather they strongly point toward the psychological suffering (stress, anxiety and depression) as a consequence of the sound sensation and its physiological causes of unknown origin at present. The future will confirm or invalidate our explanation, but we would be surprised if psychophysiological theoretical explanations such as Jastreboff’s popular Tinnitus model turns out to be correct.
Publications
- (2020). Real-time monitoring and regulating auditory cortex alpha activity in patients with chronic tinnitus. Journal of Neural Engineering
Malekshahi, A., Malekshahi, R., Czornik, M., Dax, J., Wolpert, S., Bauer, H., ... & Birbaumer, N.
(See online at https://doi.org/10.1088/1741-2552/ab57d5)
