Banca de DEFESA: ESLAINE SANTOS E SANTOS
Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.DISCENTE : ESLAINE SANTOS E SANTOS
DATA : 09/06/2021
HORA: 10:00
LOCAL: ConferênciaWeb https://conferenciaweb.rnp.br/webconf/ppgfisdefesas
TÍTULO:
CHARACTERIZATION OF DELAY TIMES IN THE SYNCHRONIZATION OF THE BRAIN FUNCTIONAL NETWORKS
PALAVRAS-CHAVES:
Functional brain networks. Dynamics Functional Networks. Delay Time. TVG. REA.
PÁGINAS: 108
GRANDE ÁREA: Ciências Exatas e da Terra
ÁREA: Física
RESUMO:
One of the ways to study the brain is through complex networks, because like many systems in nature, it is also considered a complex system. Functional brain networks (RBN) characterize the brain considering its functionality when obtaining the relationship between its different elements through measures of brain activity. Most of the works on RBN found in the literature have a static approach, without considering brain dynamics. Another problem when studying the brain is the construction of functional networks that use synchronization methods that do not consider a possible delay in synchronizations, because due to the own physiology of the brain, there may be a delay in synchronizations and if we only consider the synchronizations that are in phase, we would be losing information. Rosário et al. (2015), proposed a synchronization method called Motif Synchronization (MS), where it is possible to obtain the time series synchronization for different delays. In this way, the method estimates the delay that occurred for the maximum synchronization between two electrodes, what we call the delay time (DT). The objective of this work is to explore the different characteristics of this index in healthy subjects in baseline conditions, in order to use it as a new index in the characterization of brain functional networks. To this end, we compared the DT in functional brain networks of different individuals, simulating different experimental conditions and exploring three hypotheses: the existence of a characteristic delay time for the studied sample or for different brain regions; the dependence of the DT with the distance between electrodes. In addition to these analyzes, we used the DT to assess the influence of the conduction volume on the Functional Brain Networks. The results show that there is a growing monotonous relationship between distance and delay time. No characteristic delay time was seen for each brain region. There is evidence that the volume conduction influences the synchronization of the nearest electrodes. Some individuals have a greater influence on the volume conduction in more distant regions of the brain. The investigation of the pattern of the distribution of delay times showed that the synchronization between more distant electrodes has little influence on the effect of the conduction volume when compared to the synchronizations of the nearest electrodes and that these distant synchronizations exhibit characteristic DT of 9 ms and 24 ms. The analysis made of the DT distribution, for electrodes distant from the same brain regions, showed that the edges showed shorter delay times compared to the DT distribution for electrodes distant from different areas. We found that the pattern of DT distribution of intra and inter-hemispheric electrode pairs is the same. The different results showed that the delay times between 0 and 1 ms are predominantly due to the volume conduction and that there are characteristic times that will depend on the regions that are analyzed. The results show the importance of the synchronization methods that consider the delay in the synchronizations, as well as obtaining a filtering of the minimum delay times in order to remove connections influenced by the volume conduction.
MEMBROS DA BANCA:
Externo(a) à Instituição - GABRIELA CASTELLANO
Externo(a) à Instituição - JEAN FABER FERREIRA DE ABREU
Presidente - 1350143 - JOSE GARCIA VIVAS MIRANDA
Externo(a) à Instituição - MIGUEL ÁNGEL MUÑOZ GARCÍA
Interno(a) - 6282496 - ROBERTO FERNANDES SILVA ANDRADE