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Comparative Analysis of the Effect of Gamma-band Entrainment through Auditory Stimulation in AD Patients and Healthy Controls

Lahijanian, Mojtaba | 2021

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 53806 (05)
  4. University: Sharif University of Technology
  5. Department: Electrical Engineering
  6. Advisor(s): Aghajan, Hamid
  7. Abstract:
  8. As the most widespread form of mental disorders, Alzheimer’s disease (AD) remains among the main challenges in neurology and in the field of neuroscience. There are still no effective drugs to cure this disease or slow its progress, and prevention methods are still not even close to having established records. However, the onset of AD has been linked to certain dysfunctions of the oscillatory frequencies of the affected brain mainly in the gamma band. Hence, an approach to consider for reversing the damaging effects of AD could involve reviving such oscillations through stimulating the neuronal networks in the brain that are known to be the source of these oscillations. A recent research has reported positive results for entraining the brain of AD mouse models with non-invasive auditory and visual stimuli, in which a reversal of some of the main neurodegenerative effects of AD has been observed in areas involved in memory formation such as the hippocampus.In this study, we examine characteristics of the brain oscillatory bands induced by 40 Hz auditory stimulation based on electroencephalography (EEG) data recorded from a group of elderly participants. We observed that when the quality of entrainment surpasses a certain level in a subject, some indicators of brain synchronization which are present in memory and cognition processes significantly improve. Specifically, the entrained oscillatory activity possesses temporal phase stability in the frontal and parietal regions. In addition, notable theta-gamma phase-amplitude coupling (PAC) is observed in data recorded from the mentioned areas. The results of the current study propose that inducing synchrony in the brain circuitry may be the mechanism for the noted improvements of sensory evoked mouse model of AD. This is explained through the principle of neuroplasticity, which states that synchronized neural activity can lead to synaptic weight boost. In other words, entraining the brain with especially-designed auditory stimuli can play a role in forcing populations of neurons to synchronize, thereby promoting neural plasticity and improved synaptic function. Our study hence provides an explanation of the mechanism by which inducing brain oscillations could enhance the functionality of the brain’s neuronal circuitry and suggest a path to the treatment of Alzheimer's Disease
  9. Keywords:
  10. Entrainment ; Electroencephalography ; Neuroplasticity ; Hippocampus ; Alzheimer ; Theta-Gamma Coupling (TGC) ; Phase-Amplitude Coupling (PAC)

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