Abnormal spontaneous regional brain activity in primary insomnia: a resting-state functional magnetic resonance imaging study

Abstract

ObjectiveInvestigating functional specialization is crucial for a complete understanding of the neural mechanisms of primary insomnia (PI). Resting-state functional magnetic resonance imaging (fMRI) is a useful tool to explore the functional specialization of PI. However, only a few studies have focused on the functional specialization of PI using resting-state fMRI and results of these studies were far from consistent. Thus, the current study aimed to investigate functional specialization of PI using resting-state fMRI with amplitude of low frequency fluctuations (ALFFs) algorithm.MethodsIn this study, 55 PI patients and 44 healthy controls were included. ALFF values were compared between the two groups using two-sample t-test. The relationship of abnormal ALFF values with clinical characteristics and duration of insomnia was investigated using Pearson’s correlation analysis.ResultsPI patients showed lower ALFF values in the left orbitofrontal cortex/inferior frontal gyrus, right middle frontal gyrus, left inferior parietal lobule, and bilateral cerebellum posterior lobes, while higher ALFF values in the right middle/inferior temporal that extended to the right occipital lobe. In addition, we found that the duration of PI negatively correlated with ALFF values in the left orbitofrontal cortex/inferior frontal gyrus, and the Pittsburgh Sleep Quality Index score negatively correlated with ALFF values in the left inferior parietal lobule.ConclusionThe present study added information to limited studies on functional specialization and provided evidence for hyperarousal hypothesis in PI.

Disrupted Topology of Frontostriatal Circuits Is Linked to the Severity of Insomnia

“…In a recent study, Chen et al discovered that female insomniacs had increased activation of the anterior insula with salience networks, and they further revealed the relationship between blood-oxygen-level dependent (BOLD) in insula and the EEG gamma frequency power (Chen et al, 2014). Li et al also reported a stronger connectivity between the bilateral superior parietal lobe and the right insular lobe in insomnia (Li et al, 2014). More recently, Wang et al found an increased regional homogeneity (ReHo) value in the left insula in insomnia patients (Wang et al, 2016).…”

“…Using task-based fMRI, Martin et al reported that poor quality sleepers showed smaller activations in the right IFG, right MFG, and bilateral insula compared with good quality sleepers during an immediate and impulsive monetary decision task (Martin et al, 2015). By using the superior parietal lobe (SPL) as a seed, Li et al illustrated that insomnia patients exhibited increased connectivity between the SPL and the right IFGtri, right insula lobe, right ventral anterior cingulate cortex (ACC), left ventral posterior cingulate cortex, and right splenium of the corpus callosum, which represent brain regions critical for spatial and verbal working memory (Li et al, 2014). Moreover, Altena et al discovered that insomnia patients showed a hypoactivation in the IFG during performance in a category and letter fluency task, which recovered after sleep therapy.…”

Reduced prefrontal activation during verbal fluency task in chronic insomnia disorder: a multichannel near-infrared spectroscopy study

“…However, recent research results of fMRI and structural neuroimaging studies are not consistent with our results. They do not have a relationship with the PFC25 or exhibit different areas associated with insomnia symptoms 24,26,62…”

“…Second, the different methodologies may affect the discrepancies in results. In this study, we utilized VFT, whereas previous studies observed correlations under the no-task state 24–26,62. Finally, the diversity of clinical manifestations of insomnia patients and duration of insomnia symptoms may contribute to the discrepancy 24,35,36…”

Resting state functional connectivity in primary insomnia, generalized anxiety disorder and controls

“…Findings primarily showed greater brain entropy and reduced rsFC in PI within important brain structures (e.g., hippocampus) and networks (e.g., DMN), and these rsFC differences correlated with scores on the Pittsburgh Sleep Quality Index (PSQI, Buysse et al, 1989b). Other such rsFC measures used to compare PI and controls include amplitude of low frequency fluctuations (ALFF) and regional homogeneity (ReHo), and investigators using these approaches have suggested that differences may reflect hyperarousal in PI (Dai et al, 2016; Dai et al, 2014; Li et al, 2016a). Importantly, these measures have also been shown to correlate with PSQI scores.…”