中枢神经系统感染患儿脑脊液中利奈唑胺浓度测定方法的初步研究

目的：建立测定利奈唑胺在中枢神经系统感染患儿脑脊液中浓度的高效液相色谱法（HPLC）。方法：采用Syncronis C18柱（5 μm,4.6 mm×250 mm）;流动相为乙腈:水（含0.2%磷酸）=27∶73;流速1.0 mL/min;检测波长254 nm;柱温30 ℃。结果：利奈唑胺在脑脊液浓度为0.2~40 μg/mL范围内浓度和峰面积线性关系良好,标准曲线为As=0.553 9C-0.019 3（r=0.999 9,n=5）。最低定量限、低浓度、中浓度、高浓度的日内和日间变异RSD均<9%,准确度范围为99%~112%,提取回收率在85%~107%。稳定性考察RSD<8%。结论：该方法准确性高、灵敏度好且操作简便,适用于监测利奈唑胺在中枢神经系统感染患儿脑脊液中的浓度,进而为利奈唑胺的个体化用药提供依据。     

Spatiotemporal flow of information in the early visual pathway

The spatial components of a visual scene are processed neurally in a sequence of coarse features followed by fine features. This coarse‐to‐fine temporal stream was initially considered to be a cortical function, but has recently been demonstrated in the dorsal lateral geniculate nucleus. The goal of this study was to test the hypothesis that coarse‐to‐fine processing is present at earlier stages of visual processing in the retinal ganglion cells that supply lateral geniculate nucleus (LGN) neurons. To compare coarse‐to‐fine processing in the cat's visual system, we measured the visual responses of connected neuronal pairs from the retina and LGN, and separate populations of cells from each region. We found that coarse‐to‐fine processing was clearly present at the ganglion cell layer of the retina. Interestingly, peak and high‐spatial‐frequency cutoff responses were higher in the LGN than in the retina, indicating that there was a progressive cascade of coarse‐to‐fine information from the retina to the LGN to the visual cortex. The analysis of early visual pathway receptive field characteristics showed that the physiological response interplay between the center and surround regions was consistent with coarse‐to‐fine features and may provide a primary role in the underlying mechanism. Taken together, the results from this study provided a framework for understanding the emergence and refinement of coarse‐to‐fine processing in the visual system.     

Visualization of the amygdalo–hippocampal border and its structural variability by 7T and 3T magnetic resonance imaging

The amygdala and the hippocampus are two adjacent structures in the medial temporal lobe that have been broadly investigated in functional and structural neuroimaging due to their central importance in sensory perception, emotion, and memory. Exact demarcation of the amygdalo‐hippocampal border (AHB) is, however, difficult in conventional structural imaging. Recent evidence suggests that, due to this difficulty, functional activation sites with high probability of being located in the hippocampus may erroneously be assigned to the amygdala, and vice versa. In the present study, we investigated the potential of ultra‐high‐field magnetic resonance imaging (MRI) in single sessions for detecting the AHB in humans. We show for the first time the detailed structure of the AHB as it can be visualized in T1‐weighted 7T in vivo images at 0.5‐mm³ isotropic resolution. Compared to data acquired at 3T, 7T images revealed considerably more structural detail in the AHB region. Thus, we observed a striking inter‐hemispheric and interindividual variability of the exact anatomical configuration of the AHB that points to the necessity of individual imaging of the AHB as a prerequisite for accurate anatomical assignment in this region. The findings of the present study demonstrate the usefulness of ultra‐high‐field structural MRI to resolve anatomical ambiguities of the human AHB. Highly accurate morphometric and functional investigations in this region at 7T may allow addressing such hitherto unexplored issues as whether the structural configuration of the AHB is related to functional differences in amygdalo‐hippocampal interaction. Hum Brain Mapp 35:4316–4329, 2014. © 2014 Wiley Periodicals, Inc .     

Frequency‐dependent neural activity in Parkinson's disease

The brainstem and basal ganglia are important in the pathophysiology of Parkinson's disease (PD). Reliable and sensitive detection of neural activity changes in these regions should be helpful in scientific and clinical research on PD. In this study, we used resting state functional MRI and amplitude of low frequency fluctuation (ALFF) methods to examine spontaneous neural activity in 109 patients with PD. We examined activity in two frequency bands, slow‐4 (between 0.027 and 0.073 Hz) and slow‐5 (0.010–0.027 Hz). Patients had decreased ALFF in the striatum and increased ALFF in the midbrain, and changes were more significant in slow‐4. Additionally, changes in slow‐4 in both basal ganglia and midbrain correlated with the severity of the parkinsonism. The ALFF in the caudate nucleus positively correlated with the dose of levodopa, while the ALFF in the putamen negatively correlated with the disease duration in both slow‐4 and slow‐5 bands. In addition, the ALFF in the rostral supplementary motor area negatively correlated with bradykinesia subscale scores. Our findings show that with a large cohort of patients and distinguishing frequency bands, neural modulations in the brainstem and striatum in PD can be detected and may have clinical relevance. The physiological interpretation of these changes needs to be determined. Hum Brain Mapp 35:5815–5833, 2014. © 2014 Wiley Periodicals, Inc.