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Evidence of inverse cascades in the cerebral dynamics: Spontaneous symmetry breaking during arterial inflow
  • Christian ,
  • David López Pérez
Institute of Neuroscience, Trinity College, Dublin, Ireland
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David López Pérez
Neurocognitive Development Lab and Developmental Psychology Unit, Faculty of Psychology, University of Warsaw, Warsaw, Institute of Neuroscience, Trinity College, Dublin, Ireland
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Cerebral fluid dynamics require a reverse energy mechanism to transport water and metabolites from tissue into veins \cite{Hladky2014,Nedergaard2013,Kerskens2018}. Recent findings in active flow of bacteria have shown that such a mechanism involving backward energy cascades, so-called inverse cascades \cite{Kraichnan1973} may exist only during spontaneously broken mirror-symmetries \cite{Moffatt1969,Biferale2012,Slomka2017}. Here, we wanted to investigate whether and, if so when symmetries break during a heart cycle. We used multiple spin echos (MSE)s \cite{Deville1979,Eska1981,Bowtell1990} in magnetic resonance imaging (MRI) which can detect broken spherical symmetries. We found MSEs in brain tissue which appeared during arterial pulsation in a highly synchronized fashion in most parts of the brain. The timing suggests that the reverse energy flow is initiated during the energy injection of the heartbeat and ends with the isovolumetric vessel contraction. This interleaved process may explain how the illusive pulse wave traveling through the brain emerges as well as underlying principles of cerebral autoregulation and neurovascular coupling \cite{Kerskens2018}