RESUMEN
BACKGROUND: With the development of imaging techniques, evidence of abnormal neural activity has been implicated in patients with somatization disorder (SD). It remains unclear whether abnormal spontaneous neural activities are related to specific frequency bands. In this study, resting-state functional magnetic resonance imaging (fMRI) using the frequency-specific amplitude of low frequency fluctuation (ALFF) approach was applied to investigate changes in spontaneous neural activity in different frequency bands in patients with SD. METHODS: Twenty-five first-episode, medication-naive patients with SD and 28 age-, sex-, education-matched healthy controls (HCs) underwent resting-state fMRI. The ALFF method with the classical low-frequency (0.01 - 0.08 Hz), slow-5 (0.01 - 0.027 Hz) and slow-4 (0.027 - 0.08 Hz) bands was employed to analyze the data. RESULTS: With the classical low-frequency and slow-5 bands, patients with SD showed significantly increased ALFF in the left orbitofrontal cortex (OFC) and reduced ALFF in the right cerebellum compared with HCs. With the slow-4 band, patients with SD exhibited significantly reduced ALFF in the right cerebellum compared with HCs. However, no significant correlation was observed between the ALFF value in the left OFC or right cerebellum and clinical/cognitive variables. CONCLUSIONS: Our findings indicate that there are abnormal regional activities of the left OFC and right cerebellum in first-episode, treatment-naive patients with SD, suggesting that these alterations occur early in the course of the disease and are independent of medication status. Our study provides novel evidence that different regional activities of the frontal-cerebellar circuit may be involved in the pathophysiology of SD.
Asunto(s)
Imagen por Resonancia Magnética , Preparaciones Farmacéuticas , Encéfalo , Mapeo Encefálico , Cerebelo/diagnóstico por imagen , Lóbulo Frontal/diagnóstico por imagen , Humanos , Trastornos Somatomorfos/diagnóstico por imagenRESUMEN
Microgravity causes multiple changes in physical and mental levels in humans, which can induce performance deficiency among astronauts. Studying the variations in brain activity that occur during microgravity would help astronauts to deal with these changes. In the current study, resting-state functional magnetic resonance imaging (rs-fMRI) was used to observe the variations in brain activity during a 7-day head down tilt (HDT) bed rest, which is a common and reliable model for simulated microgravity. The amplitudes of low frequency fluctuation (ALFF) of twenty subjects were recorded pre-head down tilt (pre-HDT), during a bed rest period (HDT0), and then each day in the HDT period (HDT1-HDT7). One-way analysis of variance (ANOVA) of the ALFF values over these 8 days was used to test the variation across time period (p < 0.05, corrected). Compared to HDT0, subjects presented lower ALFF values in the posterior cingulate cortex (PCC) and higher ALFF values in the anterior cingulate cortex (ACC) during the HDT period, which may partially account for the lack of cognitive flexibility and alterations in autonomic nervous system seen among astronauts in microgravity. Additionally, the observed improvement in function in CPL during the HDT period may play a compensatory role to the functional decline in the paracentral lobule to sustain normal levels of fine motor control for astronauts in a microgravity environment. Above all, those floating brain activities during 7 days of simulated microgravity may indicate that the brain self-adapts to help astronauts adjust to the multiple negative stressors encountered in a microgravity environment.