VERA MAURA FERNANDES DE LIMA
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Artigo IPEN-doc 27713 The spreading depression propagation2021 - LIMA, VERA M.F. de; PEREIRA JUNIOR, ALFREDO; OLIVEIRA, GUILHERME L. deAt the transition from quiescence to propagating waves recorded in isolated retinas, a circular electric current closes in the extracellular matrix; this circular current creates a magnetic torus flow that, when entering quiescent tissue in front of the wave, recruits elements and when leaving behind, helps to build the absolute refractory state. The waving magnetic torus is the consequence of the vortex effect and explains the energy boost that drives propagation. Methods: We interpret experimental results from intrinsic and extrinsic fluorescence dyes, voltage, calcium and pH sensitive, optical signals from isolated retinas, and time series recordings using ion exchange resins: Ca, K, pH, Na, Cl recorded extracellularly at retinas, cerebellums and cortices coupled to spreading depression waves. Finally, we checked the ECoG activity, also a time series, at the transition from after discharges to spreading depression in rat hippocampus. Results: The integrated assessment of the diversified measurements led to the realization that the magnetic flow at the wavefront is a major contributor to the wave propagation mechanisms. This flow couples mass and charge flows as a swirling torus from excited to quiescent tissue. Conclusions: An alternative model of the brain is possible, apart from the classical HH and molecular biology model. Physical chemistry of charged gels and its flows explains the results. The conceptual framework uses far from equilibrium thermodynamics.Artigo IPEN-doc 22994 Macroscopic self-organized electrochemical patterns in excitable tissue and irreversible thermodynamics2016 - LIMA, VERA M.F. de; HANKE, WOLFGANGIn this paper we make the assertion that the key to understand the emergent properties of excitable tissue (brain and heart) lies in the application of irreversible thermodynamics. We support this assertion by pointing out where symmetry break, phase transitions both in structure of membranes as well as in the dynamic of interactions between membranes occur in excitable tissue and how they create emergent low dimensional electrochemical patterns. These patterns are expressed as physiological or physiopathological concomitants of the organ or organism behavior. We propose that a set of beliefs about the nature of biological membranes and their interactions are hampering progress in the physiology of excitable tissue. We will argue that while there is no direct evidence to justify the belief that quantum mechanics has anything to do with macroscopic patterns expressed in excitable tissue, there is plenty of evidence in favor of irreversible thermodynamics. Some key predictions have been fulfilled long time ago and they have been ignored by the mainstream literature. Dissipative structures and phase transitions appear to be a better conceptual context to discuss biological self-organization. The central role of time as a global coupling agent is emphasized in the interpretation of the presented results.