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Models of coupled phase oscillators are used to describe a wide variety of phenomena in neuroimaging. These models typically rest on the premise that oscillator dynamics do not evolve beyond their respective limit cycles, and hence that interactions can be described purely in terms of phase differences. Whilst mathematically convenient, the restrictive nature of phase-only models can limit their explanatory power. We therefore propose a generalisation of dynamic causal modelling that incorporates both phase and amplitude. This allows for the separate quantifications of phase and amplitude contributions to the connectivity between neural regions. We show, using model-generated data and simulations of coupled pendula, that phase-amplitude models can describe strongly coupled systems more effectively than their phase-only counterparts. We relate our findings to four metrics commonly used in neuroimaging: the Kuramoto order parameter, cross-correlation, phase-lag index, and spectral entropy. We find that, with the exception of spectral entropy, the phase-amplitude model is able to capture all metrics more effectively than the phase-only model. We then demonstrate, using local field potential recordings in rodents and functional magnetic resonance imaging in macaque monkeys, that amplitudes in oscillator models play an important role in describing neural dynamics in anaesthetised brain states.
This article was published in the following journal.
Cross-frequency coupling (CFC) between neuronal oscillations reflects an integration of spatially and spectrally distributed information in the brain. Here, we propose a novel framework for detecting ...
Coupling of neuronal oscillations may reflect and facilitate the communication between neuronal populations. Two primary neuronal coupling modes have been described: phase-coupling and amplitude-coupl...
Understanding changes in brain rhythms provides useful information to predict the onset of a seizure and to localize its onset zone in epileptic patients. Brain rhythms dynamics in general, and phase-...
We report on the first, to the best of our knowledge, sub-second, - infrared (IR) spectroscopic measurements of thin organic films employing a laser-based phase-amplitude polarimeter in reflection geo...
Cross frequency coupling (CFC) is emerging as a fundamental feature of brain activity, correlated with brain function and dysfunction. Many different types of CFC have been identified through applicat...
The aim of the protocol is to document intra-observer and inter-observer variability with dynamic contour tonometry, and will also test the theory that pulse amplitude, as measured by dyna...
To compare the radiological parameters measured by dynamic 4D CT in the analysis of patellofemoral involvement of subjects (amplitude of patellofemoral tilt angle variations, coefficient o...
In vitro studies suggest that low levels of amplitude-modulated electromagnetic fields may modify cell growth. We have identified specific frequencies that may block cancer cell growth. We...
One concern about repeated intravitreal injections of bevacizumab (Avastin) and ranibizumab (Lucentis) in wet age related macular degeneration, is that in addition to blocking the protein...
Laparoscopic surgery can induce hemodynamic pertubations. Pneumoperitoneum, inevitable in laparoscopic surgery, induces increase in intra-abdominal pressure, which can decrease cardiac out...
Functionalization of exogenous substances to prepare them for conjugation in PHASE II DETOXIFICATION. Phase I enzymes include CYTOCHROME P450 enzymes and some OXIDOREDUCTASES. Excess induction of phase I over phase II detoxification leads to higher levels of FREE RADICALS that can induce CANCER and other cell damage. Induction or antagonism of phase I detoxication is the basis of a number of DRUG INTERACTIONS.
The period from onset of one menstrual bleeding (MENSTRUATION) to the next in an ovulating woman or female primate. The menstrual cycle is regulated by endocrine interactions of the HYPOTHALAMUS; the PITUITARY GLAND; the ovaries; and the genital tract. The menstrual cycle is divided by OVULATION into two phases. Based on the endocrine status of the OVARY, there is a FOLLICULAR PHASE and a LUTEAL PHASE. Based on the response in the ENDOMETRIUM, the menstrual cycle is divided into a proliferative and a secretory phase.
The interval between two successive CELL DIVISIONS during which the CHROMOSOMES are not individually distinguishable. It is composed of the G phases (G1 PHASE; G0 PHASE; G2 PHASE) and S PHASE (when DNA replication occurs).
The period of the CELL CYCLE following DNA synthesis (S PHASE) and preceding M PHASE (cell division phase). The CHROMOSOMES are tetraploid in this point.
The complex series of phenomena, occurring between the end of one CELL DIVISION and the end of the next, by which cellular material is duplicated and then divided between two daughter cells. The cell cycle includes INTERPHASE, which includes G0 PHASE; G1 PHASE; S PHASE; and G2 PHASE, and CELL DIVISION PHASE.