ABSTRACT
Subjective tinnitus refers to the subjective sound perception of patients in the absence of an external sound stimulus.Tinnitus patients are often accompanied by emotional disorders, such as depression and anxiety, which seriously affect the quality of life of patients.Therefore, understanding the mechanism underlying the occurrence of tinnitus emotional disorders can help relieve the pain of tinnitus.Tinnitus was considered a simple ear disease in the early stages, but with the progress of neuroimaging technology and the development of animal models, increasing attention has been given to the changes in the neural structure and function of tinnitus patients.As a powerful technique for in vivo investigation of neural activity in the brain, multimodal magnetic resonance has been widely used in the study of subjective tinnitus.By observing the changes of brain structure in subjective tinnitus patients, the neural mechanism of the occurrence and development of tinnitus has been explored.This article reviewed recent multimodal magnetic resonance imaging studies on the neuroimaging mechanisms of tinnitus with mood disorders, compared the differences in neural activity between subjective tinnitus patients and healthy people, and found that the limbic system, default mode network and other neural network abnormalities were closely related to the mood disorders of tinnitus.The application and development of multimodal magnetic resonance techniques in subjective tinnitus were also discussed to elucidate the neural mechanism of subjective tinnitus accompanied by mood disorders with the help of multimodal magnetic resonance techniques.
ABSTRACT
Objective:To investigate the local consistency of inferior colliculus and ventrolateral orbital cortex by resting-state functional magnetic resonance imaging (fMRI) in rats with noise induced deafness and its relationship with anxiety- and depression-like behavior.Methods:Twenty-four clean grade male four-weeks old SD rats were randomly divided into noise group and control group with 12 rats in each group.Rats in the noise group were exposed to 122 dB broadband strong noise for 2 hours to induce severe bilateral hearing loss, while rats in the control group were placed in a quiet environment. Hearing thresholds were assessed by auditory brainstem response (ABR) test. The open field test (OFT) was conducted to examine anxiety-depression related behavior, and the local consistency in the rat brain was evaluated by fMRI.SPM12 software was used to process fMRI data, and Pearson correlation analysis was conducted by SPSS 22.0 software to calculate the correlation between fMRI data and behavior.Results:The results of ABR showed that the full band hearing threshold of rats in the noise group was higher than that of rats in the control group ((85.417±6.463) dB, (20.083±8.853) dB, t=46.168, P<0.001). And compared with control group, the rats in the noise group showed obvious anxiety-depression-like behavior in the open field test, that was, low activity level.The results of OFT showed that the total distance ((39.912±5.696) m, (47.993±10.820)m, t=-2.289, P=0.032), average moving speed ((13.306±1.900)cm/s, (15.998±3.607)cm/s, t=-2.290, P=0.032) and standing times ((13.333±5.960), (23.500±7.323), t=-3.730, P=0.001) of the rats in the noise group were all lower than those in the control group. Compared with the control group, the local consistency of hypothalamus in the noise group was significantly enhanced, while the local consistency of ventrolateral orbital cortex was significantly reduced, and the abnormal neural activity was lateralized. The correlation analysis showed that the neural activity of the inferior colliculus was negatively correlated with the total distance of rats in the noise group moving in the open field( r=-0.691, P=0.013), while the neural activity of the ventrolateral orbital cortex was not significantly correlated with the anxiety-depression-like behavior in the open field. Conclusions:The neural activity of inferior colliculus is closely related to anxious-depression behavior in rats with noise-induced deafness, while the ventrolateral orbital cortex may be related with other behaviors.
ABSTRACT
Small GTPases are key molecular switches that bind and hydrolyze GTP in diverse membrane- and cytoskeleton-related cellular processes. Recently, mounting evidences have highlighted the role of various small GTPases, including the members in Arf/Arl, Rab, and Ran subfamilies, in cilia formation and function. Once overlooked as an evolutionary vestige, the primary cilium has attracted more and more attention in last decade because of its role in sensing various extracellular signals and the association between cilia dysfunction and a wide spectrum of human diseases, now called ciliopathies. Here we review recent advances about the function of small GTPases in the context of cilia, and the correlation between the functional impairment of small GTPases and ciliopathies. Understanding of these cellular processes is of fundamental importance for broadening our view of cilia development and function in normal and pathological states and for providing valuable insights into the role of various small GTPases in disease processes, and their potential as therapeutic targets.