Intra and inter: Alterations in functional brain resting-state networks in patients with functional constipation

Abstract

Background: Functional constipation (FCon), is a symptom-based functional gastrointestinal disorder without an organic etiology and altering brain structure and function. However, previous studies mainly focused on isolated brain regions involved in brain plasticity. Therefore, little is known about the altered large-scale interaction of brain networks in FCon.

Methods: For this study, we recruited 20 patients with FCon and 20 healthy controls. We used group independent component analysis to identify resting-state networks (RSNs) and documented intra- and inter-network alterations in the RSNs of the patients with FCon.

Results: We found 14 independent RSNs. Differences in the intra-networks included decreased activities in the bilateral caudate of RSN 3 (strongly related to emotional and autonomic processes) and decreased activities in the left precuneus of RSN 10 (default mode network). Notably, the patients with FCon exhibited significantly decreased interactive connectivity between RSNs, mostly involving the connections to the visual perception network (RSN 7-9).

Conclusion: Compared with healthy controls, patients with FCon had extensive brain plastic changes within and across related RSNs. Furthermore, the macroscopic brain alterations in FCon were associated with interoceptive abilities, emotion processing, and sensorimotor control. These insights could therefore lead to the development of new treatment strategies for FCon.

Keywords: brain plasticity; functional constipation; functional network connectivity; independent component analysis; resting-state networks.

FIGURE 1

Spatial maps for each RSN. Each RSN map was obtained using one-sample t-test across all individual independent components (p < 0.05 after FDR correction). The color bar indicates the t-value of the one-sample t-test. RSN, resting-state networks.

FIGURE 2

The results of the intranetwork difference between FCon patients and healthy controls. Altered functional activities were found in RSN 3 (bilateral basal ganglia and thalamus) and RSN 10 (default mode network). No difference was found in other RSNs. The color bar indicates the t-value of the two-sample t-test between FCon patients and healthy controls. A negative t-value means significantly lower functional activity in the FCon patients. FCon, functional constipation; RSN, resting-state networks.

FIGURE 3

FCon-related differences in brain functional network connectivity between RSNs. The blue line between relative RSNs means significantly lower connectivity strength in FCon patients. FCon, functional constipation; RSN, resting-state networks.

FIGURE 4

Results of component combination between each pair of the identified RSNs. The blue lines show the correlation of p-value; the red dotted line shows the user p-value threshold.