title: A novel cross-frequency coupling detection method using the generalized Morse wavelets.
abstract: Cross-frequency coupling (CFC) occurs when non-identical frequency components entrain one another. A ubiquitous example from neuroscience is low frequency phase to high frequency amplitude coupling in electrophysiological signals. Seminal work by Canolty revealed CFC in human ECoG data. Established methods band-pass the data into component frequencies then convert the band-passed signals into the analytic representation, from which we infer the instantaneous amplitude and phase of each component. Though powerful, such methods resolve signals with respect to time and frequency without addressing the multiresolution problem.
  
  
  
  We build upon the ground-breaking work of Canolty and others and derive a wavelet-based CFC detection algorithm that efficiently searches a range of frequencies using a sequence of filters with optimal trade-off between time and frequency resolution. We validate our method using simulated data and analyze CFC within and between the primary motor cortex and dorsal striatum of rats under ketamine-xylazine anesthesia.
  
  
  
  Our method detects the correct CFC in simulated data and reveals CFC between frequency bands that were previously shown to participate in corticostriatal effective connectivity.
  
  
  
  Other CFC detection methods address the need to increase bandwidth when analyzing high frequency components but none to date permit rigorous bandwidth selection with no a priori knowledge of underlying CFC. Our method is thus particularly useful for exploratory studies.
  
  
  
  The method developed here permits rigorous and efficient exploration of a hypothesis space and is particularly useful when the frequencies participating in CFC are unknown.
authors.affiliation: Program in Neuroscience, 1101 E. 10th St., Bloomington, IN 47405, United States; Cognitive Science Program, 1900 E. 10th St., Bloomington, IN 47405, United States; Indiana University, Bloomington, United States. Electronic address: alexander_nakhnikian@hms.harvard.edu.
authors.forename: A
authors.initials: A
authors.lastname: Nakhnikian
authors.affiliation: Santa Cruz Institute for Particle Physics, 1156 High St., Santa Cruz, CA 95064, United States; University of California, Santa Cruz, United States.
authors.forename: S
authors.initials: S
authors.lastname: Ito
authors.affiliation: Department of Psychological and Brain Sciences, 1101 E. 10th St., Bloomington, IN 47405, United States; Indiana University, Bloomington, United States.
authors.forename: L L
authors.initials: LL
authors.lastname: Dwiel
authors.affiliation: Department of Psychological and Brain Sciences, 1101 E. 10th St., Bloomington, IN 47405, United States; Indiana University, Bloomington, United States.
authors.forename: L M
authors.initials: LM
authors.lastname: Grasse
authors.affiliation: Program in Neuroscience, 1101 E. 10th St., Bloomington, IN 47405, United States; Department of Psychological and Brain Sciences, 1101 E. 10th St., Bloomington, IN 47405, United States; Indiana University, Bloomington, United States.
authors.forename: G V
authors.initials: GV
authors.lastname: Rebec
authors.affiliation: Department of Psychological and Brain Sciences, 1101 E. 10th St., Bloomington, IN 47405, United States; Indiana University, Bloomington, United States.
authors.forename: L N
authors.initials: LN
authors.lastname: Lauridsen
authors.affiliation: Program in Neuroscience, 1101 E. 10th St., Bloomington, IN 47405, United States; Department of Physics, 727 E. 3rd St., Bloomington, IN 47405, United States; Indiana University, Bloomington, United States.
authors.forename: J M
authors.initials: JM
authors.lastname: Beggs
mesh_terms: D000465:Algorithms; D000758:Anesthesia; D000778:Anesthetics, Dissociative / Q000494:pharmacology; D000818:Animals; D003198:Computer Simulation; D003342:Corpus Striatum / Q000502:physiology; D006993:Hypnotics and Sedatives / Q000494:pharmacology; D007649:Ketamine / Q000494:pharmacology; D008297:Male; D009044:Motor Cortex / Q000502:physiology; D009434:Neural Pathways / Q000502:physiology; D017207:Rats, Sprague-Dawley; D058067:Wavelet Analysis; D014991:Xylazine / Q000494:pharmacology
chemical_list: D000778:Anesthetics, Dissociative; D006993:Hypnotics and Sedatives; D014991:Xylazine; D007649:Ketamine
keywords: Anesthesia; Cross-frequency coupling; Generalized Morse wavelets; In vivo electrophysiology; Signal processing