Regional brain activation during proximal stomach distention in humans: A positron emission tomography study

BACKGROUND & AIMS: Hypersensitivity to proximal gastric distention due to abnormal central nervous system processing of visceral stimuli has been suggested as a possible underlying pathophysiologic mechanism in functional dyspepsia. However, the cortical regions activated by distention of the proximal stomach have not been identified. The aim of this study was to investigate regional brain activation during painful and nonpainful proximal gastric distention in humans. METHODS: Positron emission tomography of the brain was performed in 11 healthy volunteers during 4 conditions: (1) no distention and isobaric distention to the individual thresholds for (2) first, (3) marked, and (4) unpleasant sensation. Data were analyzed using statistical parametric mapping. RESULTS: During maximal distention relative to baseline, significant (P corrected <.05) regional brain activation occurred in the left and right gyrus postcentralis (Brodmann area [BA] 43), the left gyrus temporalis superior (BA 38), the right gyrus frontalis inferior (BA 47, orbitofrontal cortex), the right midanterior cingulate gyrus (BA 24), the right anterior insula, and the left cerebellar hemisphere. These areas showed a progressive increase in activation with increasing intensity of the distending stimulus. CONCLUSIONS: We found evidence for a neuronal network processing distention stimuli of the proximal stomach that is overall consistent with the "visceral stimulation network" described in the literature. In addition, we found activation of the orbitofrontal cortex, confirming its role as a convergence zone for processing of food-related stimuli and regulation of hunger, appetite, satiety, and food intake. We found no evidence for a functional neuroanatomic divergence in the processing of noxious and innocuous gastric stimuli.     

磁共振弥散张量成像与静息态功能磁共振成像联合应用对艾滋病患者轻度认知功能下降的初步研究

目的 应用磁共振弥散张量成像(DTI)与静息态功能磁共振成像(rs-fMRI)及两种图像融合技术探讨AIDS患者轻度认知功能下降白质损害与皮层功能区损害的分布及相互关系.方法 对26例经蒙特利尔认知评估量表(MoCA量表)评估的AIDS轻度认知功能下降患者(AIDS 组)和30名健康志愿者(健康对照组),行全脑DTI和rs-fMRI检查,获得全脑各向异性分数值(FA值)降低脑区分布图和以后扣带回为种子点静息态默认模式网络脑功能连接图,并采用图像融合技术将两组图像进行融合.结果 AIDS组脑白质FA值降低脑区为左楔前叶(t=4.0499,P＜0.005)和右侧的楔前叶(t=5.1553,P＜0.005)、额上回(t=5.1517、5.1484,均P＜0.005)、额中回(t=4.1444,P＜0.005)、中央前回(t=3.7395,P＜0.005)、枕叶(t=7.2236,P＜0.005)、顶下小叶(t=4.1450,P＜0.005);静息态与后扣带回功能连接相关脑区为左侧的扣带回(t=32.78,P＜0.005)、楔前叶(t=4.51,P＜0.005)、额上回(t=14.33、4.53,均P＜0.005)、颞中回(t=10.01、5.72,P＜0.005)、颞下回(t=5.99,P＜0.005)、海马旁回(t=7.63,P＜0.005)和右侧的后扣带回(t=34.81,P＜0.005)、楔前叶(t=32.09,P＜0.005)、额上回(t=14.12,P＜0.005)、额中回(t=17.71,P＜0.005)、颞上回(t=14.59,P＜0.005)和颞中回(t=11.83,P＜0.005);与后扣带回功能连接减弱相关脑区为左侧的楔前叶(t=5.39,P＜0.01)、前扣带回(t=3.66,P＜0.01)、小脑扁桃体(t=7.51,P＜0.01)和右侧的顶上小叶(t=4.44,P＜0.01)、海马旁回(t=3.69,P＜0.01)和小脑扁桃体(t=6.15,P＜0.01).图像融合分析显示,AIDS组左侧楔前叶脑白质FA值降低脑区其皮层功能活动显著减弱;左楔前叶、右侧的楔前叶、额上回、额中回FA值减低脑区其皮层功能活动受影响不大.结论 多个脑区脑白质神经纤维失连接和相关联皮层功能活动下降及代偿共同参与了AIDS轻度认知功能下降的发病过程.     

Brain activation in response to visual sexual stimuli in male patients with right middle cerebral artery infarction: The first case-control functional magnetic resonance imaging study

Sexual dysfunction is a common problem after cerebral infarction; however, little is known about sexual arousal in poststroke patients. Thus, this study aimed to investigate brain activation in response to visual sexual stimuli in patients with right middle cerebral artery (MCA) territory infarction using functional magnetic resonance imaging (fMRI). Using fMRI in 20 participants (11 right MCA infarction patients and 9 age-matched healthy controls), we assessed brain activation elicited by visual sexual stimuli (erotic images) and visual nonsexual stimuli (landscape images). In right MCA infarction patients, the left dorsolateral prefrontal cortex and the left frontal subgyral area were more strongly activated by visual sexual stimuli than by nonvisual sexual stimuli. Brain areas that were more activated by visual sexual stimuli in right MCA infarction patients than in controls included the right parahippocampal gyrus and the bilateral frontal subgyral area. These fMRI results suggest that brain activation patterns in response to visual sexual stimuli might be influenced by right MCA infarction. Further research is needed to explore the association between sexual dysfunction and brain activation in poststroke patients.     

Brain mechanism of itch in atopic dermatitis and its possible alteration through non-invasive treatments

Atopic dermatitis (AD) is a common chronic skin disease that is characterized by intense pruritus and has high impairment of quality of life. AD is often described as “the itch that rashes, rather than the rash that itches”. Several studies suggest that mechanisms of central modulation play an important role in the development and maintenance of chronic itch. Therefore, treating the neurosensory aspects of itch is an important part in the management of chronic itch. However, little attention has been paid to the role of the central nervous system in the processing of itch in AD. Targeting itch-related anatomical structures in the brain with non-invasive treatments such as psychological interventions and transcranial Direct Current Stimulation (tDCS) could have an antipruritic effect in AD. Therefore, in this review article, we discuss the current progress in brain imaging research of itch, as well as the efficacy of non-invasive interventions for itch relief in this patient group.