Signals & Systems Course Project - Spring 2023

Analysis of Phase Locking Value during Olfactory Stimulation as a Biomarker for Alzheimer's Disease in EEG Signals

This repository contains my course project for the Signals & Systems course instructed by Dr. Hamid K. Aghajan at Sharif University of Technology.

Project Overview

The goal of this project was to identify early biomarkers for Alzheimer's disease and related brain disorders through analysis of EEG signals during olfactory stimulation.

Key aspects explored:

• Understanding the link between olfactory dysfunction and neurodegenerative diseases like Alzheimer's

• Using electroencephalography (EEG) to capture brain signal patterns

• Preprocessing and analyzing EEG signals

• Calculating phase locking value (PLV) to quantify phase synchronization between EEG channels

• Comparing PLV responses to olfactory stimulation between Alzheimer's patients and healthy controls

  

Repository Contents

The repository contains the following key files:

• SignalsSystems_Project1402.pdf: Original project report
• README.md: This file
• code/: Folder containing MATLAB code files for EEG preprocessing, PLV analysis, and result visualization
• data/: Sample input EEG data provided for analysis
• results/: Key output plots and visualizations generated from analysis

Running the Analysis

The codes are available in the code/ folder. MATLAB and EEG-Lab should be installed to run the codes and view the stimulations.

References

• Neurodegenerative Diseases. (2022). National Institute of Environmental Health Sciences. https://www.niehs.nih.gov/research/supported/health/neurodegenerative/index.cfm

• Marin, C., Vilas, D., Langdon, C., Alobid, I., López-Chacón, M., Haehner, A., Hummel, T., & Mullol, J. (2018). Olfactory Dysfunction in Neurodegenerative Diseases. Current Allergy and Asthma Reports, 18. https://doi.org/10.1007/s11882-018-0796-4

• Neural Oscillations – Interpreting EEG Frequency Bands. (n.d.). iMotions. https://imotions.com/blog/learning/best-practice/neural-oscillations/

• Munia, T. T. K., & Aviyente, S. (2019). Time-Frequency Based Phase-Amplitude Coupling Measure For Neuronal Oscillations. Scientific Reports, 9(1). https://doi.org/10.1038/s41598-019-48870-2

• Mild Cognitive Impairment (MCI). (2023). Mayo Clinic. https://www.mayoclinic.org/diseases-conditions/mild-cognitive-impairment/symptoms-causes/syc-20354578#:~:text=Overview,mental%20function%20has%20%22slipped.%22

• Tremblay, C., & Frasnelli, J. (2018). Olfactory and Trigeminal Systems Interact in the Periphery. Chemical Senses, 43(8), 611–616. https://doi.org/10.1093/chemse/bjy049

• Sedghizadeh, M. J., Aghajan, H., & Vahabi, Z. (2023). Brain electrophysiological recording during olfactory stimulation in mild cognitive impairment and Alzheimer disease patients: An EEG dataset. Data in Brief, 48, 109289. https://doi.org/10.1016/j.dib.2023.109289

• Sedghizadeh MJ, Hojjati H, Ezzatdoost K, Aghajan H, Vahabi Z, Tarighatnia H (2020) Olfactory response as a marker for Alzheimer’s disease: Evidence from perceptual and frontal lobe oscillation coherence deficit. PLOS ONE 15(12): e0243535. https://doi.org/10.1371/journal.pone.0243535

• Maharajh, K., Teale, P., Rojas, D.C., & Reite, M.L. (2010). Fluctuation of gamma-band phase synchronization within the auditory cortex in schizophrenia. Clinical Neurophysiology, 121(4), 542-548. https://doi.org/10.1016/j.clinph.2009.12.010

• Costa, T., Rognoni, E., & Galati, D. (2006). EEG phase synchronization during emotional response to positive and negative film stimuli. Neuroscience Letters, 406(3), 159-164. https://doi.org/10.1016/j.neulet.2006.06.039

• Womelsdorf, T., & Fries, P. (2007). The role of neuronal synchronization in selective attention. Current Opinion in Neurobiology, 17(2), 154-160. https://doi.org/10.1016/j.conb.2007.02.002

• López, M. E., Pusil, S., Pereda, E., Maestú, F., & Barceló, F. (2019). Dynamic low frequency EEG phase synchronization patterns during proactive control of task switching. NeuroImage, 186, 70-82. https://doi.org/10.1016/j.neuroimage.2018.10.068

• Palva, J. M., & Palva, S. (2018). Functional integration across oscillation frequencies by cross-frequency phase synchronization. European Journal of Neuroscience, 48(7), 2399-2406. https://doi.org/10.1111/ejn.13767

• Biel, A. L., Minarik, T., & Sauseng, P. (2021). EEG cross-frequency phase synchronization as an index of memory matching in visual search. NeuroImage, 235, 117971. https://doi.org/10.1016/j.neuroimage.2021.117971 Let me know if any clarification or additional information is needed!