Page 16 - JCBP-2-1

Journal of Clinical and
Basic Psychosomatics MRI and functional constipation

that patients with FC exhibited decreased inter-module be linked to changes in WM microstructure . The
[57]
connectivity between the BGN and limbic networks . intricate influence of underlying structural connections
[45]
They also showed an increased nodal degree in the right on functional networks has also been demonstrated .
[58]
PostCen and PreCen within the sensorimotor network Surface-based and voxel-based morphological analyses
(SMN), decreased nodal degree in the left PCUN within were performed to assess cortical thickness, volume, and
DMN, and increased nodal efficiency in the right PostCen, surface, as well as GMV and WMV of brain regions. DTI
PreCen, middle INS, and left superior temporal gyrus (STG) coupled with probabilistic tractography was conducted
within SMN, as well as the right ventral lateral prefrontal to detect WM microstructure and assess structural
cortex within DMN . In conclusion, patients with FC connectivity.
[47]
showed abnormal node degree/efficiency in regions and
intra-module connections involved in somatic and sensory 3.1. Changes in morphometry of brain regions
processing, emotional processing, and motor control, Surface-based and voxel-based morphology analyses,
reflecting an abnormal reaction to visceral discomfort and utilizing conventional structural MRI techniques, suggest
the adjustment of emotional consciousness. that FC exhibits alterations in the morphometry of brain
In fact, during resting-state scanning, subjects also regions involved in emotional regulation, somatic-sensory
[49]
experience uncontrolled fluctuations in neural activity . and motor control, and self-referential processing.
The connectivity patterns of brain networks differ Studies investigating cortical morphology indicate
across different temporal scales . Dynamic functional that patients with FC exhibit reduced cortical thickness
[50]
connectivity (dFC), based on sliding-window analysis, in the left MFG, DMPFC, VMPFC, right dACC, left OFC,
quantifies the temporal variations of RSFC and significantly PCC/PCUN, middle temporal gyrus (MTG), and SMA.
enhances our understanding of the functional dynamics of Additionally, reduced cortical volume is observed in the
the brain . The dFC analyses revealed that, compared with MTG, PreCen, and PCUN/cuneus [59,60] . The decreased
[51]
HC, patients with FC demonstrated a reduced occurrence cortical thickness and volume may be linked with the
rate and decreased mean dwell time in a state characterized impaired functions of cognitive control, executive
by complex and tight connectivity between the DMN and functions, emotional processing, and self-reflection.
[52]
the cognitive control network (CCN) . Both CCN and Additionally, reduced cortical surface was found in the
DMN play crucial roles in coordinating information in PreCen, which might be associated with dysfunctions
the human body, particularly endogenous information . of motor control [59,60] . Gray matter is formed by brain
[53]
The absence of this state suggests that patients with FC neuronal cells, enveloped in a myelin sheath, which forms
[61]
may have impaired internal task processing. Further WM . Voxel-based morphology studies indicate that
investigations have revealed significant differences in patients with FC display reduced GMV in the right MFG,
dynamic functional coupling patterns between patients left INS, ACC, right OFC, left PreCen, and THA [62,63] .
with FC and HC, particularly in connections related to FC_F demonstrated higher GMV than FC_M in regions
the aINS. Specifically, patients with FC showed stronger implicated in homeostatic afferents (e.g., left INS and
RSFC between aINS and regions such as ACC, posterior bilateral THA), emotional arousal (e.g., right AMY, right
cingulate cortex (PCC)/medial OFC, right angular gyrus, HIPP, and right OFC), and sensorimotor cortex (e.g., right
and cerebellum crus II, and weaker RSFC between aINS PreCen, bilateral PostCen, and bilateral supramarginal
and THA, superior frontal gyrus (SFG), lingual gyrus, gyrus [SMG]), along with higher WMV in the bilateral
[62]
and superior occipital gyrus (SOG) than HC . These HIPP, right SMG, and left PostCen . All these regions play
[52]
changes in functional coupling patterns could imply that an important role in emotion and autonomic regulation,
patients with FC might have a diminished perception and pain perception, and cognitive processing. Changes in
responsiveness to gut stimuli [54,55] . structure reflect abnormalities in these corresponding
functions in patients with FC.
These neuroimaging studies have consistently
demonstrated that FC was primarily linked to functional 3.2. Alterations in white matter microstructure
abnormalities in brain regions and networks involved in In DTI analysis, the metrics considered include fractional
emotion regulation, motor control, and somatic sensation. anisotropy (FA), mean diffusivity (MD), axial diffusivity

3. Structural MRI studies of FC (AD), and radial diffusivity (RD). A high FA value indicates
well-organized and coherent bundles of WM fibers. An
Previous studies have indicated that brain functional increased MD value indicates greater water diffusion,
abnormalities may be linked to structural changes . potentially indicative of tissue damage. AD measures water
[56]
Furthermore, morphometric changes could potentially diffusion along the principal orientation of WM fibers,

Volume 2 Issue 1 (2024) 8 https://doi.org/10.36922/jcbp.1463