RESEARCH PAPER
Structural Integrity in the Genu of Corpus Callosum Predicts
Conflict-induced Functional Connectivity Between Medial Frontal
Cortex and Right Posterior Parietal Cortex
Peng Liu,
a,b
Yang Yu,
a
Shudan Gao,
a
Jinbo Sun,
a
Xuejuan Yang,
a
Peng Liu
a
and Wei Qin
a
*
a
Engineering Research Center of Molecular and Neuro Imaging of the Ministry of Education, School of Life Science and Technology,
Xidian University, Xi’an, Shaanxi 710071, China
b
School of Computer and Communication, Lanzhou University of Technology, Lanzhou, Gansu 710050, China
Abstract—
Studies using the flanker task have reported that response conflict is detected by the medial frontal cor-
tex (MFC). As a conflict alert system, the MFC shows enhanced functional communication with task-related
regions. Previous studies have revealed individual differences in functional connectivity during cognitive task
performance. However, the mechanisms underlying these individual differences remain unclear. In the current
study, electroencephalography (EEG) was recorded while 30 subjects performed a flanker task that was modified
to exclude feature integration and contingency learning. The diffusion tensor imaging (DTI) data were collected
the day before the EEG session. FCz-P3/4 theta phase synchronization was used to measure functional connec-
tivity between the MFC and posterior parietal cortex (PPC). Hierarchical regression analyses were used to assess
the relationship between MFC-PPC conflict-induced theta phase synchronization and white matter integrity in sig-
nificant regions derived from tract-based spatial statistics (TBSS) analysis. As expected, MFC-PPC theta phase
synchronization was significantly enhanced during conflict, suggesting a conflict-induced functional connectiv-
ity. However, these findings were only found in the right hemisphere, which may be related to the asymmetrical
role of the bilateral PPC in response conflict processing. Furthermore, hierarchical regression analyses revealed
that 44% of individual variability in FCz-P4 conflict-induced theta phase synchronization could be explained by
variations in axial diffusivity (AD) in the genu of the corpus callosum (gCC). These results demonstrated that
structural integrity in the gCC predicts conflict-induced functional connectivity between the MFC and right
PPC.
Ó 2017 IBRO. Published by Elsevier Ltd. All rights reserved.
Key words: functional connectivity, structural connectivity, individual difference, phase synchronization.
INTRODUCTION
Conflict processing is the ability of humans to
appropriately adjust behavior according to the
environment and goal demands. Convergent evidence
suggests that conflict processing is accomplished by
collaboration between anatomically distributed cortical
regions, including the medial frontal cortex (MFC),
lateral prefrontal cortex (LPFC), posterior parietal cortex
(PPC), and other cortical regions (Ridderinkhof et al.,
2004; Liston et al., 2006). Collaboration between the
MFC and other regions indicates that there may be a neu-
ral oscillatory mechanism underlying functional communi-
cation among them.
Phase synchronization is proposed to be a
mechanism of neural communication that enables the
long-scale functional connectivity (Varela et al., 2001;
Fell and Axmacher, 2011). Recently, researchers have
examined the role of mid-frontal theta activity (4.5–8 Hz)
in conflict processing (Cavanagh and Frank, 2014). Sev-
eral studies have suggested that theta phase synchro-
nization signals the need for control to regions
responsible for control, such as the LPFC (Cavanagh
et al., 2009; Cohen and van Gaal, 2013). These findings
support the conflict monitoring theory which suggest that
https://doi.org/10.1016/j.neuroscience.2017.10.017
0306-4522/Ó 2017 IBRO. Published by Elsevier Ltd. All rights reserved.
*
Correspondence to: W. Qin, Engineering Research Center of
Molecular and Neuro Imaging of the Ministry of Education, School
of Life Science and Technology, Xidian University, Xi’an, Shaanxi
710071, China. Fax: +86-29-81891060.
E-mail addresses: liupeng_lut@foxmail.com, wqin@xidian.edu.cn
(W. Qin).
Abbreviations: AD, axial diffusivity; CSD, current-source-density; DTI,
diffusion tensor imaging; EEG, electroencephalography; EOG,
electrooculogram; gCC, genu of the corpus callosum; ITI, inter-trial
interval; LPFC, lateral prefrontal cortex; MFC, medial frontal cortex;
PPC, posterior parietal cortex; RTs, reaction time; TBSS, tract-based
spatial statistics.
NEUROSCIENCE
RESEARCH ARTICLE
P. Liu et al. / Neuroscience 366 (2017) 162–171
162