基于功能磁共振成像的肝豆状核变性患者纹状体亚区损害及临床分析

目的基于功能磁共振成像分析肝豆状核变性（Wilson disease, WD）患者纹状体亚区神经功能损害及其与临床相关分析，探讨其神经心理学症状可能的致病机制。方法收集WD患者29例和健康志愿者30例，进行3.0 T磁共振功能磁共振成像及临床量表测试，采用mICA工具箱的group ICA功能将壳核和尾状核分成8个亚区，做全脑功能连接，提取功能连接异常区域的值与临床量表测试结果做相关性分析。结果与对照组相比，WD患者左侧尾状核中部与全脑未发现功能增强或减弱区域，余感兴趣区与全脑功能连接不同程度减弱。左侧尾状核前部（ROI5）-中扣带回功能连接值与简易智能状态量表（MMSE）值呈显著负相关（r=-0.47，P=0.009）；右侧尾状核前部（ROI6）-中扣带回功能连接值与MMSE值呈显著负相关（r=-0.46，P=0.011）；右侧尾状核中部（ROI8）-右侧岛叶功能连接值与MMSE值呈显著负相关（r=-0.38，P=0.041）。结论右侧尾状核前中部与背外侧前额叶功能连接减弱，双侧壳核前部与丘脑功能连接减弱，可能破坏皮质-纹状体-丘脑回路引起认知功能损害；参与记忆及动作相关认知的突显网络、默认模式网络的通路连接受阻则可能是WD患者认知障碍的神经病理机制。     

Effect of stromal cell-derived factor-1/CXCR4 axis in neural stem cell transplantation for Parkinson’s disease

Previous studies have shown that neural stem cell transplantation has the potential to treat Parkinson’s disease,but its specific mechanism of action is still unclear.Stromal cell-derived factor-1 and its receptor,chemokine receptor 4(CXCR4),are important regulators of cell migration.We speculated that the CXCR4/stromal cell-derived factor 1 axis may be involved in the therapeutic effect of neural stem cell transplantation in the treatment of Parkinson’s disease.A Parkinson’s disease rat model was injected with 6-hydroxydopamine via the right ascending nigrostriatal dopaminergic pathway,and then treated with 5μL of neural stem cell suspension(1.5×104/L)in the right substantia nigra.Rats were intraperitoneally injected once daily for 3 days with 1.25 mL/kg of the CXCR4 antagonist AMD3100 to observe changes after neural stem cell transplantation.Parkinson-like behavior in rats was detected using apomorphine-induced rotation.Immunofluorescence staining was used to determine the immunoreactivity of tyrosine hydroxylase,CXCR4,and stromal cell-derived factor-1 in the brain.Using quantitative real-time polymerase chain reaction,the mRNA expression of stromal cell-derived factor-1 and CXCR4 in the right substantia nigra were measured.In addition,western blot assays were performed to analyze the protein expression of stromal cell-derived factor-1 and CXCR4.Our results demonstrated that neural stem cell transplantation noticeably reduced apomorphine-induced rotation,increased the mRNA and protein expression of stromal cell-derived factor-1 and CXCR4 in the right substantia nigra,and enhanced the immunoreactivity of tyrosine hydroxylase,CXCR4,and stromal cell-derived factor-1 in the brain.Injection of AMD3100 inhibited the aforementioned effects.These findings suggest that the stromal cell-derived factor-1/CXCR4 axis may play a significant role in the therapeutic effect of neural stem cell transplantation in a rat model of Parkinson’s disease.This study was approved by the Animal Care and Use Committee of Kunming Medical University,China(approval No.SYXKK2015-0002)on April 1,2014.     

Hippocampal‐striatal functional connectivity supports processing of temporal expectations from associative memory

The hippocampus and dorsal striatum are both associated with temporal processing, but they are thought to play distinct roles. The hippocampus has been reported to contribute to storing temporal structure of events in memory, whereas the striatum contributes to temporal motor preparation and reward anticipation. Here, we asked whether the striatum cooperates with the hippocampus in processing the temporal context of memorized visual associations. In our task, participants were trained to implicitly form temporal expectations for one of two possible time intervals associated to specific cue‐target associations, and subsequently were scanned using ultra‐high‐field 7T functional magnetic resonance imaging. During scanning, learned temporal expectations could be violated when the pairs were presented at either the associated or not‐associated time intervals. When temporal expectations were met during testing trials, activity in left and right hippocampal subfields and right putamen decreased, compared to when temporal expectations were not met. Further, psycho‐physiological interactions showed that functional connectivity between left hippocampal subfields and caudate decreased when temporal expectations were not met. Our results indicate that the hippocampus and striatum cooperate to process implicit temporal expectation from mnemonic associations. Our findings provide further support for a hippocampal‐striatal network in temporal associative processing.     

Ablation of striatal somatostatin interneurons affects MSN morphology and electrophysiological properties,and increases cocaine‐induced hyperlocomotion in mice

The striatum is mainly composed by medium spiny neurons (95 %) (MSNs). Although outnumbered, in other brain regions such as the hippocampus and the cortex, somatostatin interneurons (SSTi) are known to control and fine‐tune the activity of principal cells. This information is still fragmented for the striatum. Here, we questioned the striatal functional consequences of the selective ablation of SSTi in the striatum at the behavioural and cellular levels. We identified increased excitability coupled with decreased distal spine density in MSNs from SSTi‐ablated mice. Although the ethological behavioural analysis did not reveal differences between the groups, SSTi‐ablated mice were significantly more sensitive to the locomotor effects of cocaine without changes in motivation. This was accompanied by increased expression of the dopamine transporter (DAT) in the ventral striatum. Altogether, we show that SSTi are important players in the maintenance of MSN excitability and spine density impacting on mechanisms towards hyperdopaminergic states.     

The spatial cerebral damage caused by larger infarct and β-amyloid toxicity is driven by the anatomical/functional connectivity

Large cerebral infarctions are major predictors of death and severe disability from stroke. Conversely, data concerning these types of infarctions and the affected adjacent brain circuits are scarce. It remains to be determined if the co-morbid concurrence of large infarct and β-amyloid (Aβ) toxicity can precipitate the early development of dementia. Here, we described a dose-dependent effect of a unilateral striatal injection of vasoconstrictive endothelin-1 (ET-1) along with Aβ toxicity on CNS pathogenesis; driven by the anatomical and functional networks within a brain circuit. After 21 days of treatment, a high dose (60 pmol) of ET-1 (E60) alone caused the greatest increase in neuroinflammation, mainly in the ipsilateral striatum and distant regions with synaptic links to the striatal lesion such as white matter (subcortical white matter, corpus callosum, internal capsule, anterior commissure), gray matter (globus pallidus, thalamus), and cortices (cingulate, motor, somatosensory, entorhinal). The combined E60 + Aβ treatment also extended perturbation in the contralateral hemisphere of these rats, such as increased deposition of amyloid precursor protein fragments associated with the appearance of degenerating cells and the leakage of laminin from the basement membrane across a compromised blood–brain barrier. However, the cerebral damage induced by the 6 pmol ET-1 (E6), Aβ and E6 + Aβ rats was not detrimental enough to injure the complete network. The appreciation of the causal interactions among distinct anatomical units in the brain after ischemia and Aβ toxicity will help in the design of effective and alternative therapeutics that may disassociate the synergistic or additive association between the infarcts and Aβ toxicity.     

The effect of chronic neuroglycopenia on resting state networks in GLUT1 syndrome across the lifespan

Glucose transporter type I deficiency syndrome (GLUT1DS) is an encephalopathic disorder due to a chronic insufficient transport of glucose into the brain. PET studies in GLUT1DS documented a widespread cortico‐thalamic hypometabolism and a signal increase in the basal ganglia, regardless of age and clinical phenotype. Herein, we captured the pattern of functional connectivity of distinct striatal, cortical, and cerebellar regions in GLUT1DS (10 children, eight adults) and in healthy controls (HC, 19 children, 17 adults) during rest. Additionally, we explored for regional connectivity differences in GLUT1 children versus adults and according to the clinical presentation. Compared to HC, GLUT1DS exhibited increase connectivity within the basal ganglia circuitries and between the striatal regions with the frontal cortex and cerebellum. The excessive connectivity was predominant in patients with movement disorders and in children compared to adults, suggesting a correlation with the clinical phenotype and age at fMRI study. Our findings highlight the primary role of the striatum in the GLUT1DS pathophysiology and confirm the dependency of symptoms to the patients' chronological age. Despite the reduced chronic glucose uptake, GLUT1DS exhibit increased connectivity changes in regions highly sensible to glycopenia. Our results may portrait the effect of neuroprotective brain strategy to overcome the chronic poor energy supply during vulnerable ages.