Clonally related cortical cells show several migration patterns

The mammalian cerebral cortex is organized into columns of cells with common functional properties. During embryogenesis, cortical neurons are formed deep, near the lateral ventricles, and migrate radially to their final position. This observation led to the suggestion that the cortex consists of radial, ontogenetic units of clonally related neurons. In the experiments reported here, this hypothesis was tested by studying cell lineage in the rat cortex with a retroviral vector carrying the Escherichia coli beta-galactosidase gene, which can be easily visualized. Labeled, clonally related cortical neurons did not occur in simple columnar arrays. Instead, clonally related neurons entered several different radial columns, apparently by migrating along different radial glial fibers.     

Recording and interpretation of cerebral magnetic fields

Contemporary brain research progresses along two main lines: the microlevel approach explores single neurons and subcellular elements, while macrolevel studies focus on more complex cerebral functions, including behavior. This review presents results obtained mainly in our laboratory by means of an intermediate method, magnetoencephalography (MEG), which reflects cortical activity of neuronal populations at the level fo cytoarchitectonic areas. Because it is completely noninvasive, MEG can be used to study brain functions that are characteristically human.     

The neostriatal mosaic: striatal patch-matrix organization is related to cortical lamination

The basal ganglia, of which the striatum is the major component, process inputs from virtually all cerebral cortical areas to affect motor, emotional, and cognitive behaviors. Insights into how these seemingly disparate functions may be integrated have emerged from studies that have demonstrated that the mammalian striatum is composed of two compartments arranged as a mosaic, the patches and the matrix, which differ in their neurochemical and neuroanatomical properties. In this study, projections from prefrontal, cingulate, and motor cortical areas to the striatal compartments were examined with the Phaseolus vulgaris-leucoagglutinin (PHA-L) anterograde axonal tracer in rats. Each cortical area projects to both the patches and the matrix of the striatum; however, deep layer V and layer VI corticostriatal neurons project principally to the patches, whereas superficial layer V and layer III and II corticostriatal neurons project principally to the matrix. The relative contribution of patch and matrix corticostriatal projections varies among the cortical areas examined such that allocortical areas provide a greater number of inputs to the patches than to the matrix, whereas the reverse obtains for neocortical areas. These results demonstrate that the compartmental organization of corticostriatal inputs is related to their laminar origin and secondarily to the cytoarchitectonic area of origin.     

Fate-restricted neural progenitors in the mammalian cerebral cortex

During development of the mammalian cerebral cortex, radial glial cells (RGCs) generate layer-specific subtypes of excitatory neurons in a defined temporal sequence, in which lower-layer neurons are formed before upper-layer neurons. It has been proposed that neuronal subtype fate is determined by birthdate through progressive restriction of the neurogenic potential of a common RGC progenitor. Here, we demonstrate that the murine cerebral cortex contains RGC sublineages with distinct fate potentials. Using in vivo genetic fate mapping and in vitro clonal analysis, we identified an RGC lineage that is intrinsically specified to generate only upper-layer neurons, independently of niche and birthdate. Because upper cortical layers were expanded during primate evolution, amplification of this RGC pool may have facilitated human brain evolution.     

Concurrent overproduction of synapses in diverse regions of the primate cerebral cortex

Synapses develop concurrently and at identical rates in different layers of the visual, somatosensory, motor, and prefrontal areas of the primate cerebral cortex. This isochronic course of synaptogenesis in anatomically and functionally diverse regions indicates that the entire cerebral cortex develops as a whole and that the establishment of cell-to-cell communication in this structure may be orchestrated by a single genetic or humoral signal. This is in contrast to the traditional view of hierarchical development of the cortical regions and provides new insight into the maturation of cortical functions.     

G protein-coupled receptor-dependent development of human frontal cortex

The mammalian cerebral cortex is characterized by complex patterns of anatomical and functional areas that differ markedly between species, but the molecular basis for this functional subdivision is largely unknown. Here, we show that mutations in GPR56, which encodes an orphan G protein-coupled receptor (GPCR) with a large extracellular domain, cause a human brain cortical malformation called bilateral frontoparietal polymicrogyria (BFPP). BFPP is characterized by disorganized cortical lamination that is most severe in frontal cortex. Our data suggest that GPCR signaling plays an essential role in regional development of human cerebral cortex.     

Migration and differentiation of cerebral cortical neurons after transplantation into the brains of ferrets

Cells from the cerebral proliferative zones of newborn ferrets were labeled with tritiated thymidine and a fluorescent dye and were transplanted as a single-cell suspension into the occipital region of newborn ferrets. The transplanted cells became thoroughly integrated into the host environment: many cells migrated through the intermediate zone and into the cortical plate, where they developed as pyramidal neurons. Other transplanted cells came to resemble glial cells. After 1 to 2 months most transplanted neurons had taken up residence in layer 2 + 3, the normal destination of neurons generated on postnatal days 1 and 2. Thus the sequence of morphological differentiation and the eventual laminar position of the isochronically transplanted neurons closely paralleled that of their normal host counterparts.     

Rhesus monkey vestibular cortex: a bimodal primary projection field

Single units in the rhesus monkey (Macaca mulata) cortex responded to both vestibular and proprioceptive somatosensory stimuli. This bimodal response characteristic is unlike the modality specificity noted for other primary sensory fields. The vestibular field is located, contrary to previous opinion, within a distinct cytoarchitectonic area outside of area 2.     

急性中毒性脑病的CT诊断

目的探讨急性中毒性脑病的CT表现,提高对本病的认识.方法收集急性中毒性脑病18例,回顾性分析其脑部CT表现特点.结果CT表现：脑水肿18例,脑实质密度减低,脑室及脑池受压变小,严重者全脑密度呈均一性减低;蛛网膜下隙出血14例,表现为后纵裂池及天幕等处条片状高密度影;脑内出血2例,呈斑片状高密度影.结论CT能够反映中毒性脑病的病变范围、严重程度和预后情况,对临床及时正确诊治,减少后遗症具有重要意义.     

煤矿区压占土地复垦适宜性评价研究——以贵州纳雍县狗场煤矿为例

复垦土地的适宜性评价是制定土地复垦方案的前提和基础。以贵州纳雍县狗场煤矿为例,结合矿区地形、土壤等实际情况,将该矿区拟复垦土地划分为生活区、生产区、储煤场、临时煤矸场、其他附属设施区等评价单元,确定各单元主要破坏类型为压占,破坏程度为重度;并参考耕地、林地适宜性评价指标,最终确定该矿区受压占破坏严重的评价地块复垦方向均为宜耕宜林地。     

迦辽金法在管道不稳定流动分析中的应用

针对输油管道系统的组成特点，将系统划分成基本组成单元，建立了油品在单元中不稳定流动方程，并综合考虑它们的边界条件、连接条件和初始条件，通过引入线性化系数，采用迦辽金方法讨论了求解问题。该方法既具有解析解法的特点，又具有数值解法的特点。当所划分的管道单元较大时，可以得到直观的近似解析解；当所划分的管道单元较小时，可以得到更准确的数值解。与常用解析法相比，该方法可适用于各种管道结构，因其可在不同的管道单元和不同时间层上计算线性化系数，从而可以提高求解的准确性。与其它数值解法相比，由于管道单元和时间步长的选取可大可小，各管道单元的大小也可以不一样，这就提高了求解的灵活性。以此为基础，编制了计算机软件，对某输油管道进行了实际模拟分析，获得了满意结果。     

Patterning and plasticity of the cerebral cortex

The cerebral cortex of the human brain is a sheet of about 10 billion neurons divided into discrete subdivisions or areas that process particular aspects of sensation, movement, and cognition. Recent evidence has begun to transform our understanding of how cortical areas form, make specific connections with other brain regions, develop unique processing networks, and adapt to changes in inputs.     

Somatosensory cortex: structural alterations following early injury to sense organs

In mouse somatosensory cortex there are discrete cytoarchitectonic units, called "barrels." Each barrel is related to one sensory vibrissa on the muzzle. Individual vibrissae were carefully injured at birth; 12 to 43 days later, the corresponding barrels proved to be absent. Evidently the sensory periphery has an important influence on the structure of the somatosensory cortex.     

Coupling between cortical potentials from different areas

At any instant, the electroencephalogram can be classified as to (i) polarity and (ii) direction of change in polarity. This classification provides a way to measure coupling between cortical areas. The technique is simple, yet of wide potential utility for studying functional relationships between cortical areas. The results of applying this technique suggest how the potentials giving rise to the electroencephalogram may play a role in information processing in the central nervous system.     

丘陵山区果树灌溉用泵机组的优化选用

针对达州市丘陵山区果树灌溉用泵机组的使用现状,分析了选用IS 型单级单吸离心泵 机组、ZB 型自吸离心泵机组、QS 型充水式潜水电泵等普通离心泵机组的不足,提出了在缺少三 相电源的丘陵山区的水果种植专业合作社使用QG 型手压排气汽油机直联离心泵机组是最好的 方法,通过实际应用证实,使用QG 型手压排气汽油机直联离心泵机组后,水果增产效果良好。     

Direct cortical control of 3D neuroprosthetic devices

Three-dimensional (3D) movement of neuroprosthetic devices can be controlled by the activity of cortical neurons when appropriate algorithms are used to decode intended movement in real time. Previous studies assumed that neurons maintain fixed tuning properties, and the studies used subjects who were unaware of the movements predicted by their recorded units. In this study, subjects had real-time visual feedback of their brain-controlled trajectories. Cell tuning properties changed when used for brain-controlled movements. By using control algorithms that track these changes, subjects made long sequences of 3D movements using far fewer cortical units than expected. Daily practice improved movement accuracy and the directional tuning of these units.     

Toward delineating hydro-functional soil mapping units using the pedostructure concept: A case study

Current soil maps contain qualitative attributes which are challenging to integrate into agronomic models or decision support systems. In this paper, a new approach is proposed that will enable the use of soil maps as a suitable information system of soils hydrostructural properties for agronomic and environmental models. This enhancement is possible through a new methodology for characterizing the soil units on the basis of the multi-scale soil–water functionality of the pedon which is a representative soil mapping unit delineated by pedologists according to the geomorphology. The hydro-functional mapping units should represent soil mapping units that are theoretically homogenous from the perspective of the pedostructure parameters of the pedon. For the purpose of this study, the Haggerty–Cox property, West Lafayette, Indiana, USA was selected. The soil data “soil mapping units and physical characteristics” of the study area were obtained from SSURGO. Due to time and cost constraints, the research was restricted to three SSURGO soil units (SwA, Starks–Fincastle complex with 0–2% slope; MsC2, Miami silt loam, 6–12% slopes; and HoA, Hononegah fine sandy loam with 0–2% slopes) to check their spatial homogeneity according to the pedostructure parameters (PS).The discriminant statistical analysis for the area of study shows that the PS parameters are unique for each soil mapping unit and can be effectively used to characterize these units and validate their delineation. The resulting hydro-functional soil mapping units match SSURGO units but have additional physical attributes. In general, subsurface horizons (B) are more distinguishable than surface horizons (Ap), and using pedostructure parameters from both potential and shrinkage curves gives the highest distinguishing value. Results confirm that the pedostructure parameters are discriminant characteristics of the hydrostructural functioning of soils as delineated by pedologists. Having the hydro-functional soil mapping units will assist in the decision support system data analysis, which in turn, will allow for the prediction of water and chemical transport and interactions.     

Synchronization of unit activity in the cerebral cortex

Simultaneous recording with micropipette electrodes from different units in the cerebral cortex revealed that units seldom fired synchronously. However, there was a temporal relationship in unit firing even when the cortex was "aroused." This relationship was most apparent when strychnine and stimulation were applied to a sensory nerve of an animal asleep or under deep anesthesia.     

Lhx2 selector activity specifies cortical identity and suppresses hippocampal organizer fate

The earliest step in creating the cerebral cortex is the specification of neuroepithelium to a cortical fate. Using mouse genetic mosaics and timed inactivations, we demonstrated that Lhx2 acts as a classic selector gene and essential intrinsic determinant of cortical identity. Lhx2 selector activity is restricted to an early critical period when stem cells comprise the cortical neuroepithelium, where it acts cell-autonomously to specify cortical identity and suppress alternative fates in a spatially dependent manner. Laterally, Lhx2 null cells adopt antihem identity, whereas medially they become cortical hem cells, which can induce and organize ectopic hippocampal fields. In addition to providing functional evidence for Lhx2 selector activity, these findings show that the cortical hem is a hippocampal organizer.