Altered Spontaneous Brain Activity Patterns and Functional Connectivity in Adults With Intermittent Exotropia: A Resting-State fMRI Study

Abstract

The purpose of this study is to investigate brain functional changes in patients with intermittent exotropia (IXT) by analyzing the amplitude of low-frequency fluctuation (ALFF) of brain activity and functional connectivity (FC) using resting-state functional magnetic resonance imaging (rs-fMRI). There were 26 IXT patients and 22 age-, sex-, education-, and handedness-matched healthy controls (HCs) enrolled who underwent rs-fMRI. The ALFF, fractional ALFF (fALFF) values in the slow 4 and slow 5 bands, and FC values were calculated and compared. The correlations between ALFF/fALFF values in discrepant brain regions and clinical features were evaluated. Compared with HCs, ALFF/fALFF values were significantly increased in the right angular gyrus (ANG), supramarginal gyrus (SMG), inferior parietal lobule (IPL), precentral gyrus (PreCG), and the bilateral inferior frontal gyri (IFG), and decreased in the right precuneus gyrus (PCUN), left middle occipital gyrus (MOG), and postcentral gyrus (PoCG) in IXT patients. The Newcastle Control Test score was negatively correlated with ALFF values in the right IFG (r = −0.738, p < 0.001). The duration of IXT was negatively correlated with ALFF values in the right ANG (r = −0.457, p = 0.049). Widespread increases in FC were observed between brain regions, mainly including the right cuneus (CUN), left superior parietal lobule (SPL), right rolandic operculum (ROL), left middle temporal gyrus (MTG), left IFG, left median cingulate gyrus (DCG), left PoCG, right PreCG, and left paracentral gyrus (PCL) in patients with IXT. No decreased FC was observed. Patients with IXT exhibited aberrant intrinsic brain activities and FC in vision- and eye movement-related brain regions, which extend current understanding of the neuropathological mechanisms underlying visual and oculomotor impairments in IXT patients.

Altered Long- and Short-Range Functional Connectivity Density in Patients With Thyroid-Associated Ophthalmopathy: A Resting-State fMRI Study

“…The PoCG and SPG participate in the formation of dorsal visual pathway, which is responsible for processing spatial information ( 17 ). In recent years, several rs-fMRI studies focusing on other orbital diseases (e.g., glaucoma, exotropia, and blindness) have demonstrated decreased functional connectivity in the PoCG ( 17 , 36 , 37 ). As for the IPL, Nardella et al ( 38 ) suggested that this region was involved in encoding visual temporal resolution by changing the critical flicker frequency threshold.…”

Amplitude of low frequency fluctuations during resting state fMRI in autistic children

“…Additional analyses of the relationship between ALFF and structural/functional connectivity would be beneficial. Some researchers have interpreted correlations between the ALFF values of separate brain regions as indicating functional connectivity (He et al, 2021; Huang et al, 2019; Zhou et al, 2019). These studies to date have included only non‐autistic participants.…”

Abnormal cortical morphology in children and adolescents with intermittent exotropia

“…The abnormal function and structure of these visual association cortices were previously reported to be associated with strabismus. Increased regional homogeneity values in ITC ( Huang et al, 2016 ), increased amplitude of low-frequency fluctuation in the prefrontal cortex and superior temporal gyrus ( Yin et al, 2021 ), increased functional connectivity within MT area ( He et al, 2021b ) were found in the exotropic patients. The ITC may correspond to the visual area V4, a component of the ventral stream that plays a role in object perception ( Schoenfeld et al, 2002 ; Freud et al, 2016 ).…”