Análise topológica de dados em redes funcionais do cérebro humano sob efeito da Ayahuasca

Abstract

An area of great interest for scientists today is the study of real complex systems. An example of a complex system is the human brain. The present study uses the usual methods in the study of complex systems to investigate, in an exploratory way, the connectivity of the brain before and after the ingestion of Ayahuasca tea. The tools used for this work focus on the investigation of connectivity between different regions of the brain, based on data from functional magnetic resonance imaging (fMRI). These data were represented by simplicial complexes, in order to make it possible to use the techniques used to evaluate brain connectivity. The three measures used to assess brain connectivity were: (i) the Euler entropy; (ii) the curvature; and (iii) the persistent entropy. Using appropriate statistical tests, it was possible to observe changes in the phase transition point of the complex system in question. For the curvature, no significant changes were observed, however a relevant change in the participation profile of nodes during the phase transition of the system was observed. For the persistent entropy, a decrease of its value was observed for the simplices of dimension two. In this way, the present study broadens our understanding of the impact of Ayahuasca on the brain and opens the door to future studies about brain connectivity under the action of psychedelics.