The Medial Thalamus Plays an Important Role in the Cognitive and Emotional Modulation of Orofacial Pain: A Functional Magnetic Resonance Imaging-Based Study.

Yu Jin,Wenli Lai,He Liu,Xin Yang,Jue Wang,Feifei Zhang,Qiyong Gong,Hu Long,Fei Li,Hong Yang

doi:10.3389/fneur.2020.589125

Abstract

The thalamus plays a critical role in the perception of orofacial pain. We investigated the neural mechanisms of orofacial pain by exploring the intrinsic functional alterations of the thalamus and assessing the changes in functional connectivity (FC) between the thalamic subregions with significant functional alterations and other brain regions in orofacial pain using the seed-based FC approach. There were 49 participants in the orofacial pain group and 49 controls. Orofacial pain was caused by orthodontic separators. The resting-state functional magnetic resonance imaging data of the two groups were analyzed to obtain the fractional amplitude of low-frequency fluctuations (fALFF) of the thalamus; the thalamic subregions with significant fALFF abnormalities were used as seeds for FC analysis. Student's t-tests were used for comparisons. Pearson's correlation analysis was performed using SPM software. Forty-four participants with orofacial pain (mean age, 21.0 ± 0.9 years; 24 women) and 49 age- and sex-matched controls (mean age, 21.0 ± 2.6 years; 27 women) were finally included. Compared with the control group, the orofacial pain group demonstrated the following: (1) increased function in the dorsal area of the thalamus and decreased function in the medial thalamus; (2) decreased FC between the medial thalamus and 12 brain regions (p < 0.05, family-wise error corrected, voxel > 100); and (3) potential positive and negative correlations between the medial thalamus-seeded FC and visual analog scale score changes (p < 0.05, AlphaSim corrected). The findings show that the medial and dorsal thalami play important roles in orofacial pain perception, and that the medial thalamus likely plays an important role in the cognitive and emotional modulation of orofacial pain.

Highlights

Orofacial pain, an ache localized in the oral and facial regions [1], is a symptom of a variety of diseases, such as pulpitis, periodontitis, and temporomandibular joint disorder (TMD) [2]
Significant fractional amplitude of low-frequency fluctuations (fALFF) abnormalities in the orofacial pain group were demonstrated in two thalamic subregions, the medial thalamus and the dorsal area of the thalamus, and these two subregions were chosen as seeds for seed-based functional connectivity (FC) analysis by using REST
The FC of the medial thalamus significantly differed between the groups

Summary

Introduction

An ache localized in the oral and facial regions [1], is a symptom of a variety of diseases, such as pulpitis, periodontitis, and temporomandibular joint disorder (TMD) [2]. Because of the complexity of the affected regions, orofacial pain can have a deleterious effect on the patients’ daily functions (including eating, drinking, and speaking) and can seriously affect various social functions and the quality of life [5, 6]. It is well-known that the trigeminal nerve contains most sensory nerve fibers innervating orofacial tissues and is important for orofacial pain perception. The trigeminal nucleus sends the information in the ventroposterior nucleus of the thalamus, and the thalamus relays it to the cortex [7]

Methods

Results

Conclusion