Speaker: Damián Dellavale   (Instituto Balseiro – Centro Atómico Bariloche, Argentinia)

Abstract:
Cross frequency coupling (CFC) phenomenon observed in neural recordings has been proposed to be functionally involved in neuronal communication, memory formation and learning. Besides, experimental findings have shown that phase-amplitude (PAC) and phase-phase (PPC) couplings are important variants of CFC linked to physiological and pathological brain states.
In particular, the interpretation of the CFC patterns observed in local field potentials (LFP) recorded during epileptic seizures in humans remains challenging due to the fact that the ictal activity is, in general, characterized by pseudo-periodic sharp waveforms. The latter, raises the question of whether ictal CFC patterns are indicative of true interactions reflecting a mechanistic process between two independent neural oscillators, or whether it might be a more trivial consequence of spectral correlations due to the non-sinusoidal waveform constituting the recorded time series.
In the first part of this talk I will discuss our results about the role of the spectral harmonicity of the ictal activity observed in epilepsy patients undergoing intracerebral electroencephalography (stereo EEG), in connection with both the seizure onset zone classification given preoperatively by the epileptologists and the PAC patterns associated to the mechanisms of seizure propagation.
In the second part, I will briefly present our results showing that the PAC phenomenon naturally emerges in mean-field models of biologically plausible networks, as a signature of specific bifurcation structures. The proposed analysis, based on bifurcation theory, allows the identification of the mechanisms underlying oscillatory dynamics that are essentially different in the context of PAC.

References:
– Dellavale D, Urdapilleta E, Cámpora N, Velarde O, Kochen S, Mato G (2020), Spectral harmonicity distinguishes two types of ictal phase-amplitude cross frequency couplings in patients candidate to epilepsy surgery, Clinical Neurophysiology, DOI: https://doi.org/10.1016/j.clinph.2020.04.160. 

– Osvaldo Matías Velarde, Eugenio Urdapilleta, Germán Mato, and Damián Dellavale (2019), Bifurcation structure determines different phase-amplitude coupling patterns in the activity of biologically plausible neural networks, NeuroImage, Vol. 202, No. 11603.DOI: https://doi.org/10.1016/j.neuroimage.2019.11603