Ferramenta para avaliação do padrão de conectividade cortical funcional baseada na sincronização de fase

Abstract

The study of cortical processes is important to comprehend the neurological deficits and thus, allow the development of strategies to help on the treatment of such deficits. The mechanisms of integration and coordination of the activities of cortical regions may be studied with the analysis of phase synchronization between signals obtained from multiple cortical areas. Phase synchronization is a method for measuring the functional connectivity, which is, the temporal correlation for cortical areas, however is not capable of identifying the causal relations among the areas, defined as effective connectivity. In the national scenario, it still doesn t exist a profound knowledge on the techniques used to evaluate the functional cortical synchronization patterns, especially the ones based on surface electroencephalography. This work propose the development of a platform to evaluate the functional connectivity pattern, based on phase synchronization, for electroencephalographic signals. The tool was developed in MATLAB® and quantifies the phase synchronization index of electroencephalographic signals by means of the Hilbert Transform. The system was tested and its performance validated by means of synthetic sine waves and real EEG data. The results of the tests using synthetic data showed that the algorithm performs correctly, generating the expected values for signals highly synchronized and non-synchronized. A case study was performed, in which electroencephalographic data were collected from a volunteer during read-aloud tasks. The results showed significant synchronization between cortical regions responsible for reading and the production of speech. This tool has the potential to be used in applications in which it is desired to map the functional connectivity between cortical areas, such as, brain machine interfaces, neurofeedback and rehabilitation of neurological dysfunctions.