Altered spontaneous brain activity patterns in patients with hyperthyroidism exophthalmos using amplitude of low-frequency fluctuation:a resting-state fMRI study

AIM:To assess changed spontaneous brain activity in hyperthyroid exophthalmos(HE)patients by the amplitude of the low-frequency fluctuation(ALFF)method,and to analyze the correlation between brain activity and ALFF values in these patients.METHODS:Totally 18 HE and 18 hyperthyroid nonexophthalmos(HNE)patients were enrolled.The participants were tested by resting-state functional magnetic resonance imaging,and receiver operating characteristic(ROC)curves were generated to classify the ALFF values of the study population.Pearson’s correlation analysis was utilized to evaluate the relationship between the ALFF values obtained from different brain areas and clinical manifestations.RESULTS:Contrary to HNE patients,we observed lower ALFF values in the left calcarine fissure and surrounding cortex(LCFSC)in HE patients.In the ROC curve analysis of the LCFSC,the area under the curve reflected a high degree of accuracy.In addition,there was positive correlation between mean ALFF values of the LCFSC and the bestcorrected visual acuity of the affected eyes.CONCLUSION:The study displays abnormal brain activity in LCFSC in patients with HE,which might suggest pathological mechanism of visual impairment of HE patients.

Brain mechanisms of mental processing:from evoked and spontaneous brain activities to enactive brain activity

Within the context of the computer metaphor,evoked brain activity acts as a primary carrier for the brain mechanisms of mental processing.However,many studies have found that evoked brain activity is not the major part of brain activity.Instead,spontaneous brain activity exhibits greater intensity and coevolves with evoked brain activity through continuous interaction.Spontaneous and evoked brain activities are similar but not identical.They are not separate parts,but always dynamically interact with each other.Therefore,the enactive cognition theory further states that the brain is characterized by unified and active patterns of activity.The brain adjusts its activity pattern by minimizing the error between expectation and stimulation,adapting to the ever-changing environment.Therefore,the dynamic regulation of brain activity in response to task situations is the core brain mechanism of mental processing.Beyond the evoked brain activity and spontaneous brain activity,the enactive brain activity provides a novel framework to completely describe brain activities during mental processing.It is necessary for upcoming researchers to introduce innovative indicators and paradigms for investigating enactive brain activity during mental processing.

Altered brain network centrality in patients with retinal vein occlusion: a resting-state fMRI study

AIM:To explore the intrinsic brain activity variations in retinal vein occlusion(RVO)subjects by using the voxel-wise degree centrality(DC)technique.METHODS:Twenty-one subjects with RVO and twentyone healthy controls(HCs)were enlisted and underwent the resting-state functional magnetic resonance imaging(rs-f MRI)examination.The spontaneous cerebrum activity variations were inspected using the DC technology.The receiver operating characteristic(ROC)curve was implemented to distinguish the DC values of RVOs from HCs.The relationships between DC signal of definite regions of interest and the clinical characteristics in RVO group were evaluated by Pearson’s correlation analysis.RESULTS:RVOs showed notably higher DC signals in right superior parietal lobule,middle frontal gyrus and left precuneus,but decreased DC signals in left middle temporal gyrus and bilateral anterior cingulated(BAC)when comparing with HCs.The mean DC value of RVOs in the BAC were negatively correlated with the anxiety and depression scale.CONCLUSION:RVO is associated aberrant intrinsic brain activity patterns in several brain areas including painrelated as well as visual-related regions,which might assist to reveal the latent neural mechanisms.