title: Application of functional data analysis in classification and clustering of functional near-infrared spectroscopy signal in response to noxious stimuli.
abstract: We introduce the application of functional data analysis (fDA) on functional near-infrared spectroscopy (fNIRS) signals for the development of an accurate and clinically practical assessment method of pain perception. We used the cold pressor test to induce different levels of pain in healthy subjects while the fNIRS signal was recorded from the frontal regions of the brain. We applied fDA on the collected fNIRS data to convert discrete samples into continuous curves. This method enabled us to represent the curves as a linear combination of basis functions. We utilized bases coefficients as features that represent the shape of the signals (as opposed to extracting defined features from signal) and used them to train a support vector machine to classify the signals based on the level of induced pain. We achieved 94% of accuracy to classify low-pain and high-pain signals. Moreover applying hierarchical clustering on the coefficients, we found three clusters in the data which represented low-pain (one cluster) and high-pain groups (two clusters) with an accuracy of 91.2%. The center of these clusters can represent the prototype fNIRS response of that pain level.
authors.affiliation: Drexel University, School of Biomedical Engineering, Science and Health Systems, 3141 Chestnut Street, Bossone Research, Suite 718, Philadelphia, Pennsylvania 19104, United States.
authors.forename: Ahmad
authors.initials: A
authors.lastname: Pourshoghi
authors.affiliation: Drexel University, Dornsife School of Public Health, Department of Epidemiology and Biostatistics, 3215 Market Street, Nesbitt Hall, Philadelphia, Pennsylvania 19104, United States.
authors.forename: Issa
authors.initials: I
authors.lastname: Zakeri
authors.affiliation: Drexel University, School of Biomedical Engineering, Science and Health Systems, 3141 Chestnut Street, Bossone Research, Suite 718, Philadelphia, Pennsylvania 19104, United States.
authors.forename: Kambiz
authors.initials: K
authors.lastname: Pourrezaei
mesh_terms: D016000:Cluster Analysis; D005260:Female; D005625:Frontal Lobe / Q000502:physiology*; D006801:Humans; D000069550:Machine Learning; D008297:Male; D058748:Pain Perception / Q000502:physiology*; D012815:Signal Processing, Computer-Assisted; D019265:Spectroscopy, Near-Infrared / Q000379:methods*