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Analysis of rTMS in Improvement of Tinnitus using EEG and fMRI

Shariftabar Azizi, Fatemeh | 2024

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 56970 (05)
  4. University: Sharif University of Technology
  5. Department: Electrical Engineering
  6. Advisor(s): Jahed, Mehran; Asadpour, Abdureza; Hani Tabatabaei, Mozhgan; Mehrkian, Saiedeh
  7. Abstract:
  8. Tinnitus means hearing a sound without an external source. Despite the research done in relation to it, it is still an unknown phenomenon and no method has been introduced to treat it. Repetitive transcranial magnetic stimulation is one of the methods that its effectiveness in decreasing tinnitus sound is still under investigation. This technology is a non-invasive method to stimulate the brain, which modulates the activity of neurons by applying successive electromagnetic pulses on the scalp. Most of the studies conducted in this field have used clinical evaluations to investigate the effect of stimulation. Relying on this method alone to evaluate the effect of stimulation cannot take a step in understanding the brain regions involved in tinnitus and brain activity in it. In this regard, it is necessary to use brain imaging methods as methods to evaluate the effect of stimulation in addition to clinical evaluation.The aim of this exploratory study was to evaluate the effect of this stimulation on brain oscillations in chronic tinnitus and healthy control groups, using fMRI and EEG. Participants of two groups received repetitive transcranial magnetic stimulation with a frequency of 1 Hz at the junction of temporal and parietal cortex of the left hemisphere with neural navigation. Five stimulation sessions in 5 consecutive days and 1100 pulses per session were considered for the tinnitus group and two stimulation sessions in one day, 300 pulses for each session, were considered for the healthy control group. The power spectrum density of EEG and EEG-informed fMRI were calculated to investigate the effect of stimulation.Then, these parameters measured in two states pre and post of stimulation, as well as between two groups of tinnitus and healthy control, were examined and compared. Stimulation of the left temporoparietal junction with a frequency of 1 Hz led to a decrease in the amplitude of the density of the EEG power spectrum in theta, beta and gamma frequencies in tinnitus group participants and an increase in the healthy control participants. Also, the overall level of brain activity calculated using EEG-informed fMRI for one of the tinnitus participants increased after rTMS and the other decreased. In this study, for the first time, the simultaneous combination of EEG and fMRI was used to investigate the effect of applying low frequency rTMS on healthy control and tinnitus groups. Although in the current study, the changes in the cognitive level (clinical evaluations) were not sufficiently detectable, but the differences observed between tinnitus patients and healthy control participant indicate that methods such as EEG and fMRI has potential for detecting tinnitus-related changes in neuroplasticity, i.e., changes in resting state activity after rTMS
  9. Keywords:
  10. Tinnitus ; Functional Magnetic Resonance Imaging (FMRI) ; Electroencephalography ; Transcranial Magnetic Stimulation (TMS) ; Repetitive Transcranial Magnetic Stimulation ; Brain Signal

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