Analysis of fMRI data using the complex systems approach

Physiological and biological systems can be characterized as complex processes whose dynamics are constantly being influenced by nonlinear interactions. The outputs of these systems correspond to different modes of reaction due to dynamic relationships that are established between components of the system, perturbations from the external environment and changes that occur at physiological levels in the body. In this work, recent advances in the field of nonlinear dynamics are applied to fMRI data to examine the spatio-temporal properties of BOLD signal during a working memory task completion. Two groups of human subjects, one affected by schizophrenia and healthy controls, were imaged during the task completion. Recurrence properties were extracted from the time series of the most relevant voxels, using the Recurrence Plots (RP) and the Recurrence Quantitative Analysis (RQA). The purpose of the paper is to perform a description of the functional states, as well as to capture differences (if any) between the groups. Results are still preliminary but the methodology applied has margin of improvements.