Addressing Pitfalls in Phase-Amplitude Coupling Analysis with an Extended Modulation Index Toolbox
- PDF / 7,266,101 Bytes
- 27 Pages / 595.224 x 790.955 pts Page_size
- 120 Downloads / 192 Views
ORIGINAL ARTICLE
Addressing Pitfalls in Phase-Amplitude Coupling Analysis with an Extended Modulation Index Toolbox Gabriela J. Jurkiewicz1
1 ˙ · Mark J. Hunt2 · Jarosław Zygierewicz
© The Author(s) 2020
Abstract Phase-amplitude coupling (PAC) is proposed to play an essential role in coordinating the processing of information on local and global scales. In recent years, the methods able to reveal trustworthy PAC has gained considerable interest. However, the intrinsic features of some signals can lead to the identification of spurious or waveform-dependent coupling. This prompted us to develop an easily accessible tool that could be used to differentiate spurious from authentic PAC. Here, we propose a new tool for more reliable detection of PAC named the Extended Modulation Index (eMI) based on the classical Modulation Index measure of coupling. eMI is suitable both for continuous and epoched data and allows estimation of the statistical significance of each pair of frequencies for phase and for amplitude in the whole comodulogram in the framework of extreme value statistics. We compared eMI with the reference PAC measures—direct PAC estimator (a modification of Mean Vector Length) and standard Modulation Index. All three methods were tested using computer-simulated data and actual local field potential recordings from freely moving rats. All methods exhibited similar properties in terms of sensitivity and specificity of PAC detection. eMI proved to be more selective in the dimension of frequency for phase. One of the novelty’s offered by eMI is a heuristic algorithm for classification of PAC as Reliable or Ambiguous. It relies on analysis of the relation between the spectral properties of the signal and the detected coupling. Moreover, eMI generates visualizations that support further evaluation of the coupling properties. It also introduces the concept of the polar phase-histogram to study phase relations of coupled slow and fast oscillations. We discuss the extent to which eMI addresses the known problems of interpreting PAC. The Matlab® toolbox implementing eMI framework, and the two reference PAC estimators is freely available as EEGLAB plugin at https://github.com/GabrielaJurkiewicz/ePAC. Keywords Phase-amplitude coupling · Cross-frequency coupling · Ketamine induced HFO · Olfactory bulb · EEGLAB toolbox
Introduction Neuronal activity manifests itself, among others, in the form of periodic voltage fluctuations, which can be recorded as rhythms in electroencephalograms (EEG) and electrocorticograms (ECoG). Conventionally, brain rhythms are studied in discrete frequency bands, which often are attributed to distinct physiological functions (Buzs´aki and Draguhn 2004; Wang 2010). Importantly, oscillations of Gabriela J. Jurkiewicz
[email protected] 1
Faculty of Physics, University of Warsaw, L.Pasteura 5 Street, 02-093, Warsaw, Poland
2
Nencki Institute of Experimental Biology, L.Pasteura 3 Street, 02-093, Warsaw, Poland
different frequency bands can interact, which may provide a functio
Data Loading...
