title: Spatio-temporal correlations from fMRI time series based on the NN-ARx model.
abstract: For the purpose of statistical characterization of the spatio-temporal correlation structure of brain functioning from high-dimensional fMRI time series, we introduce an innovation approach. This is based on whitening the data by the Nearest-Neighbors AutoRegressive model with external inputs (NN-ARx). Correlations between the resulting innovations are an extension of the usual correlations, in which mean-correction is carried out by the dynamic NN-ARx model instead of the static, standard linear model for fMRI time series. Measures of dependencies between regions are defined by summarizing correlations among innovations at several time lags over pairs of voxels. Such summarization does not involve averaging the data over each region, which prevents loss of information in case of non-homogeneous regions. Statistical tests based on these measures are elaborated, which allow for assessing the correlation structure in search of connectivity. Results of application of the NN-ARx approach to fMRI data recorded in visual stimuli experiments are shown. Finally, a number of issues related with its potential and limitations are commented.
authors.affiliation: Cuban Neuroscience Center, Havana, Cuba.
authors.forename: J
authors.initials: J
authors.lastname: Bosch-Bayard
authors.forename: J
authors.initials: J
authors.lastname: Riera-Diaz
authors.forename: R
authors.initials: R
authors.lastname: Biscay-Lirio
authors.forename: K F K
authors.initials: KF
authors.lastname: Wong
authors.forename: A
authors.initials: A
authors.lastname: Galka
authors.forename: O
authors.initials: O
authors.lastname: Yamashita
authors.forename: N
authors.initials: N
authors.lastname: Sadato
authors.forename: R
authors.initials: R
authors.lastname: Kawashima
authors.forename: E
authors.initials: E
authors.lastname: Aubert-Vazquez
authors.forename: R
authors.initials: R
authors.lastname: Rodriguez-Rojas
authors.forename: P
authors.initials: P
authors.lastname: Valdes-Sosa
authors.forename: F
authors.initials: F
authors.lastname: Miwakeichi
authors.forename: T
authors.initials: T
authors.lastname: Ozaki
mesh_terms: D001931:Brain Mapping / Q000379:methods; D002540:Cerebral Cortex / Q000033:anatomy & histology* / Q000502:physiology*; D003198:Computer Simulation / Q000592:standards*; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D009434:Neural Pathways / Q000033:anatomy & histology / Q000502:physiology; D012044:Regression Analysis; D013997:Time Factors; D055698:Touch Perception / Q000502:physiology; D014796:Visual Perception / Q000502:physiology