Page 15 - JCBP-2-1

Journal of Clinical and
Basic Psychosomatics MRI and functional constipation

reflecting as effective connectivity, Granger causality Measurement of functional connectivity within and
analysis (GCA) has been conducted in past studies. The between resting-state networks (RSNs) plays a crucial role
results demonstrated that, in comparison to HC, patients in revealing the organizational structure of the brain. This
with FC exhibited heightened effective connectivity method reflects the communication and collaboration
originating from OFC to aINS, HIPP, and dACC, as well among different brain regions, thereby identifying distinct
as from dACC to aINS and HIPP. On the contrary, weaker functional systems . Studies have demonstrated that,
[43]
effective connectivity was observed from PreCen to aINS, when compared with HC, patients with FC exhibited
HIPP, dACC, and OFC; from SMA to aINS, HIPP, dACC, stronger FNC between RSNs. Specifically, there is
and PreCen; and from OFC to SMA [27,31] . The enhanced increased FNC in network connections of the salience
effective connectivities may induce abnormal visceral network (SN)-basal ganglia network (BGN) and DMN-left
responses and sensory integration, while the weakened control executive network (LCEN). Conversely, there is a
effective connectivities indicate a decline in motor control significant reduction in FNC in network connections of the
and a reduced readiness for the defecation response. In SN-right control executive network (RCEN) [34,43] . Within
addition, a study reveals that, when compared to FCNAD, the BGN-SN connection, functional connectivity showed
FCAD exhibits stronger effective connectivity from SMA, stronger functional connectivity in left caudate (CAU)-
PreCen, and HIPP to ACC, OFC, as well as from PreCen, left INS, right THA-left INS, right CAU-left INS, and left
HIPP, and INS to SMA, from HIPP to PreCen, and from THA-ACC. Within the SN-RCEN connection, functional
ACC and PreCen to Hy. Conversely, FCAD shows weaker connectivity exhibits weaker functional connectivity in left
effective connectivity from INS to ACC, PreCen, HIPP, INS-right dorsolateral prefrontal cortex (DLPFC) and right
and Hy and from OFC, SMA, HIPP, and INS to Hy . The INS-right DLPFC. Within the DMN-LCEN connection,
[31]
heightened effective connectivities between brain regions functional connectivity displays stronger functional
responsible for emotional arousal and somatosensory connectivity in VMPFC-left angular gyrus (ANG), PCUN-
sensation explain why FCAD presents with more left ANG, and VMPFC-left DLPFC . Additionally, the
[34]
psychiatric disorders, including anxiety and depression, FNC of SN-DMN, SN-LCEN, and SN-RCEN in FC_F is
along with abnormalities in motor control and behavioral significantly lower than that in FC_M. These results reflect
response. With regard to the impact of gender, the study abnormal self-referential and emotional processing in
reveals that FC_F have stronger effective connectivity patients with FC . Gender differences in FNC related to
[34]
from INS, THA, and SMA to amygdala (AMY) and HIPP, visceral perception and emotion regulation further confirm
and weaker effective connectivity from VMPFC to INS that FC_F is more susceptible to psychiatric factors such as
and HIPP compared to FC_M , suggesting that FC_F anxiety and depression.
[31]
are likely to exhibit abnormal cross-talk between regions In conjunction with graph theory, RS-fMRI can
involved with interoception and emotional processing.
be employed to investigate the abnormal topological
As a voxel-wise data-driven technique, functional organization of intrinsic brain functional networks in
connectivity density (FCD) mapping surpasses the patients with FC . Studies have revealed a decrease in local
[44]
constraints of seed-based approaches that identify hubs in information transmission within the functional network ,
[45]
the human brain . Studies have demonstrated decreased with changes in nodal degree/efficiency mainly observed
[41]
local FCD in the left IFG, bilateral middle frontal gyrus in the THA-cortical network . Significant differences
[45]
(MFG), ACC, and right PreCen in patients with FC . were identified between FCAD and FCNAD [46,47] .
[34]
Furthermore, FC_F exhibited significantly higher local Specifically, compared with HC, studies examining global
FCD values than FC_M in the left THA and left HIPP. topological properties have demonstrated that patients
Additionally, local FCD values in the PreCen/PostCen with FC exhibit a decrease in the normalized clustering
were negatively associated with the State-TAI (STAI), and coefficient and small-worldness [45,46,48] . Studies examining
local FCD value in the MFG was negatively associated with regional topological properties have reported that patients
SDS . These results reflect abnormal visceral sensation with FC exhibited a decreased nodal degree/efficiency in
[34]
and emotional processing functions, which are consistent the THA and rostral ACC (rACC). Additionally, decreased
with RSFC and GCA results, proving evidence that FC_F nodal efficiency was found in DMPFC/dACC and AMY
are more susceptible to emotional stress. while exhibiting an increased nodal degree/efficiency in
the inferior and superior parietal lobules. Moreover, an
2.3. Abnormal functional network increased nodal degree was found in aINS, SMA, and
connectivity (FNC) PreCen [45,48] . Furthermore, in comparison to FCNAD,
The brain, being one of the most complex systems, relies patients with FCAD displayed an increased nodal degree in
on the integrated functioning of neural networks . the PreCen . Modular topological studies have revealed
[42]
[46]
Volume 2 Issue 1 (2024) 7 https://doi.org/10.36922/jcbp.1463