scholarly journals Synergetic and Redundant Information Flow Detected by Unnormalized Granger Causality: Application to Resting State fMRI

2016 ◽  
Vol 63 (12) ◽  
pp. 2518-2524 ◽  
Author(s):  
S. Vidhusha ◽  
A. Kavitha

Autism spectrum disorders are connected with disturbances of neural connectivity. Functional connectivity is typically examined during a cognitive task, but also exists in the absence of a task. While a number of studies have performed functional connectivity analysis to differentiate controls and autism individuals, this work focuses on analyzing the brain activation patterns not only between controls and autistic subjects, but also analyses the brain behaviour present within autism spectrum. This can bring out more intuitive ways to understand that autism individuals differ individually. This has been performed between autism group relative to the control group using inter-hemispherical analysis. Indications of under connectivity were exhibited by the Granger Causality (GC) and Conditional Granger Causality (CGC) in autistic group. Results show that as connectivity decreases, the GC and CGC values also get decreased. Further, to demark the differences present within the spectrum of autistic individuals, GC and CGC values have been calculated.


2016 ◽  
Vol 28 (2) ◽  
pp. 199-209 ◽  
Author(s):  
Andrew S. Kayser ◽  
Zdeňa Op de Macks ◽  
Ronald E. Dahl ◽  
Michael J. Frank

The onset of adolescence is associated with an increase in the behavioral tendency to explore and seek novel experiences. However, this exploration has rarely been quantified, and its neural correlates during this period remain unclear. Previously, activity within specific regions of the rostrolateral PFC (rlPFC) in adults has been shown to correlate with the tendency for exploration. Here we investigate a recently developed task to assess individual differences in strategic exploration, defined as the degree to which the relative uncertainty of rewards directs responding toward less well-evaluated choices, in 62 girls aged 11–13 years from whom resting state fMRI data were obtained in a separate session. Behaviorally, this task divided our participants into groups of explorers (n = 41) and nonexplorers (n = 21). When seed ROIs within the rlPFC were used to interrogate resting state fMRI data, we identified a lateralized connection between the rlPFC and posterior putamen/insula whose strength differentiated explorers from nonexplorers. On the basis of Granger causality analyses, the preponderant direction of influence may proceed from posterior to anterior. Together, these data provide initial evidence concerning the neural basis of exploratory tendencies at the onset of adolescence.


NeuroImage ◽  
2011 ◽  
Vol 54 (4) ◽  
pp. 2683-2694 ◽  
Author(s):  
Wei Liao ◽  
Jurong Ding ◽  
Daniele Marinazzo ◽  
Qiang Xu ◽  
Zhengge Wang ◽  
...  

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