Long-term potentiation in the motor cortex

Long-term potentiation (LTP) is a model for learning and memory processes. Tetanic stimulation of the sensory cortex produces LTP in motor cortical neurons, whereas tetanization of the ventrolateral nucleus of the thalamus, which also projects to the motor cortex, does not. However, after simultaneous high-frequency stimulation of both the sensory cortex and the ventrolateral nucleus of the thalamus, LTP of thalamic input to motor cortical neurons is induced. This associative LTP occurs only in neurons in the superficial layers of the motor cortex that receive monosynaptic input from both the sensory cortex and the ventrolateral nucleus of the thalamus. Associative LTP in the motor cortex may constitute a basis for the retention of motor skills.     

Map plasticity in somatosensory cortex

Sensory maps in neocortex are adaptively altered to reflect recent experience and learning. In somatosensory cortex, distinct patterns of sensory use or disuse elicit multiple, functionally distinct forms of map plasticity. Diverse approaches-genetics, synaptic and in vivo physiology, optical imaging, and ultrastructural analysis-suggest a distributed model in which plasticity occurs at multiple sites in the cortical circuit with multiple cellular/synaptic mechanisms and multiple likely learning rules for plasticity. This view contrasts with the classical model in which the map plasticity reflects a single Hebbian process acting at a small set of cortical synapses.     

Convergent projection of three separate thalamic nuclei on to a single cortical area

Three distinct sensory-motor nuclei in the thalamus project to parietal cortex in the Virginia opossum; the ventral posterior nucleus receives inputs from somatic sensory structures and projects to layers IV and III, the ventral anterolateral nucleus receives inputs from motor structures and projects to layers IV and III and inner I, and the central intralaminar nucleus receives inputs from sensory, motor, and other structures and projects to layers VI through outer I. The physiologically defined amalgamation of somatic sensory and motor cortex is correlated, therefore, with the extent of cortex that receives convergent somatic sensory and motor input from the thalamus.     

Experimentally induced visual projections into auditory thalamus and cortex

Retinal cells have been induced to project into the medial geniculate nucleus, the principal auditory thalamic nucleus, in newborn ferrets by reduction of targets of retinal axons in one hemisphere and creation of alternative terminal space for these fibers in the auditory thalamus. Many cells in the medial geniculate nucleus are then visually driven, have large receptive fields, and receive input from retinal ganglion cells with small somata and slow conduction velocities. Visual cells with long conduction latencies and large contralateral receptive fields can also be recorded in primary auditory cortex. Some visual cells in auditory cortex are direction selective or have oriented receptive fields that resemble those of complex cells in primary visual cortex. Thus, functional visual projections can be routed into nonvisual structures in higher mammals, suggesting that the modality of a sensory thalamic nucleus or cortical area may be specified by its inputs during development.     

Mutations in a human ROBO gene disrupt hindbrain axon pathway crossing and morphogenesis

The mechanisms controlling axon guidance are of fundamental importance in understanding brain development. Growing corticospinal and somatosensory axons cross the midline in the medulla to reach their targets and thus form the basis of contralateral motor control and sensory input. The motor and sensory projections appeared uncrossed in patients with horizontal gaze palsy with progressive scoliosis (HGPPS). In patients affected with HGPPS, we identified mutations in the ROBO3 gene, which shares homology with roundabout genes important in axon guidance in developing Drosophila, zebrafish, and mouse. Like its murine homolog Rig1/Robo3, but unlike other Robo proteins, ROBO3 is required for hindbrain axon midline crossing.     

Expression of c-fos protein in brain: metabolic mapping at the cellular level

The proto-oncogene c-fos is expressed in neurons in response to direct stimulation by growth factors and neurotransmitters. In order to determine whether the c-fos protein (Fos) and Fos-related proteins can be induced in response to polysynaptic activation, rat hindlimb motor/sensory cortex was stimulated electrically and Fos expression examined immunohistochemically. Three hours after the onset of stimulation, focal nuclear Fos staining was seen in motor and sensory thalamus, pontine nuclei, globus pallidus, and cerebellum. Moreover, 24-hour water deprivation resulted in Fos expression in paraventricular and supraoptic nuclei. Fos immunohistochemistry therefore provides a cellular method to label polysynaptically activated neurons and thereby map functional pathways.     

兔舌下神经的纤维成分──HRP法研究

用ＨＲＰ法研究了兔舌下神经的纤维成分和起源。将ＨＲＰ注入舌下神经干,舌下神经核内几乎所有神经元均被标记,均为大多极细胞;三叉神经节和Ｃ２－４脊神经节出现大量标记细胞,以直径１５～３０μｍ的小细胞为主;同侧颈上节有大量标记细胞出现。结果表明：舌下神经是含有一般躯体传出、一般躯体传入和一般内脏传出３种成分的混合神经。并对传统舌下神经的概念作了补充和修正。此外,发现多例兔舌下神经干中,仅一例有小神经节存在,由此认为它是一种不恒定结构。对舌下神经干、舌肌及舌粘膜３组标记的感觉神经元比较,推测出舌肌梭本体感觉可能经由三叉神经的舌神经支传导。     

Two gustatory systems: facial and vagal gustatory nuclei have different brainstem connections

The gustatory sense in catfish consists of two dissociable components, a facial nerve system used for food selection and a vagal nerve system involved in swallowing. Neural tracing experiments demonstrate that the primary sensory nucleus for the facial gustatory system is connected to the reticular formation and trigeminal nuclei. In contrast, the primary sensory nucleus for the vagal gustatory system is connected to the motoneurons that mediate swallowing. These results provide anatomical evidence for parallel gustatory systems within the vertebrate central nervous system.     

兔眼上斜肌的神经支配——HRP法研究

将辣根过氧化物酶（ＨＲＰ）注射于兔侧眼上斜肌,结果显示：双侧滑车神经核和双侧三叉神经节均出现标记细胞,注射侧滑车神经核占５．６８％,对侧占９４．３２％;注射侧三叉神经节占９８．３１％,对侧占１．６９％;前髓帆有明显标记的交叉纤维。表明眼上斜肌的运动和感觉均受双侧支配,其感觉神经以同侧为主,运动神经以对侧为主。     

Massive cortical reorganization after sensory deafferentation in adult macaques.

After limited sensory deafferentations in adult primates, somatosensory cortical maps reorganize over a distance of 1 to 2 millimeters mediolaterally, that is, in the dimension along which different body parts are represented. This amount of reorganization was considered to be an upper limit imposed by the size of the projection zones of individual thalamocortical axons, which typically also extend a mediolateral distance of 1 to 2 millimeters. However, after extensive long-term deafferentations in adult primates, changes in cortical maps were found to be an order of magnitude greater than those previously described. These results show the need for a reevaluation of both the upper limit of cortical reorganization in adult primates and the mechanisms responsible for it.     

A map of visual space induced in primary auditory cortex

Maps of sensory surfaces are a fundamental feature of sensory cortical areas of the brain. The relative roles of afferents and targets in forming neocortical maps in higher mammals can be examined in ferrets in which retinal inputs are directed into the auditory pathway. In these animals, the primary auditory cortex contains a systematic representation of the retina (and of visual space) rather than a representation of the cochlea (and of sound frequency). A representation of a two-dimensional sensory epithelium, the retina, in cortex that normally represents a one-dimensional epithelium, the cochlea, suggests that the same cortical area can support different types of maps. Topography in the visual map arises both from thalamocortical projections that are characteristic of the auditory pathway and from patterns of retinal activity that provide the input to the map.     

Synaptic changes in layer 2/3 underlying map plasticity of developing barrel cortex

The functional and anatomical rearrangements of cortical sensory maps accompanying changes in experience are not well understood. We examined in vivo and in vitro how the sensory map and underlying synaptic connectivity of the developing rat barrel cortex are altered when the sensory input to the cortex is partially deprived. In the nondeprived cortex, both the sensory responses and synaptic connectivity between columns were strengthened through an increase in the synaptic connection probability between L2/3 pyramids in adjacent columns. This was accompanied by a selective growth of L2/3pyramid axonal arbors between spared columns. In contrast, deprived and nondeprived cortical columns became weakly connected in their L2/3 pyramid connections.     

麦洼牦牛 Hoxa10基因克隆、原核表达及组织表达谱

从麦洼牦牛肾脏组织提取总RNA,以已公布牛 Hoxa10编码区序列设计引物,RT PCR法克隆麦洼牦牛 Hoxa10基因;构建原核表达载体pET 32a(+) Hoxa10,并在大肠杆菌表达系统中表达,SDS PAGE检测融合蛋白;采用RT PCR检测该基因在麦洼牦牛各组织中的表达分布。结果表明：从麦洼牦牛肾脏中克隆 Hoxa10基因的CDs区,大小为285 bp,编码94个氨基酸残基,与牛、猪和绵羊的 Hoxa10同源性高;经IPTG诱导,pET 32a(+) Hoxa10在BL21中可表达1个大小约为28 ku的特异蛋白;在牦牛各组织中,肾脏和肺脏中表达较高,但在心脏表达量极低或不表达。     

黄河中下游东方蜜蜂种质资源工蜂色型多样性研究

应用形态学标记对蜜蜂进行分类的方法一直被人们广泛应用,色型标记是蜜蜂形态学标记中重要指标.对采自黄河中下游14地区296群东方蜜蜂的4 440只工蜂唇部、小盾片及背板8个色型进行分析,发现东方蜜蜂色型丰富,与西方蜜蜂色型有很大不同,分别绘制出东方蜜蜂第2～4背板、唇基和小盾片Sc区0～9级,上唇0～5级,小盾片K区和B区分别为0～7级和0～6级色型图谱.14采样地区应用唇部、背板以及小盾片色型分别可以聚为2大类,与总聚类结果相似. 8个色型特征在主成分分析中共提出2个特征值大的因子,主因子分类结果显示14采样地区东方蜜蜂分为三大类:黑色东方蜜蜂、棕色东方蜜蜂和黄色东方蜜蜂.上述东方蜜蜂色型图和聚类结果为制定东方蜜蜂色型标准图谱和建立中国东方蜜蜂亚种分类系统提供有利参考依据.     

Visual instruction of the neural map of auditory space in the developing optic tectum

Neural maps of visual and auditory space are aligned in the adult optic tectum. In barn owls, this alignment of sensory maps was found to be controlled during ontogeny by visual instruction of the auditory spatial tuning of neurons. Large adaptive changes in auditory spatial tuning were induced by raising owls with displacing prisms mounted in spectacle frames in front of the eyes; neurons became tuned to sound source locations corresponding to their optically displaced, rather than their normal, visual receptive field locations. The results demonstrate that visual experience during development calibrates the tectal auditory space map in a site-specific manner, dictating its topography and alignment with the visual space map.     

大比例尺数字化地形图缩编的方法研究

地形图缩编是一项系统性、规范性很强的工作。在城市宏观管理和规划中,往往还需要更小比例尺的地形图,如1∶2 000或者1∶5 000。在现有1∶500地形图基础上,若采用重测的方法需要耗费大量的资金和时间。文章论述了由1∶500的地形图缩编至1∶2 000地形图的方法,并详细阐述了其中地形图中各要素缩编的关键过程的处理技巧。该方法可显著地提高缩编过程的效率,节省工作量及大量费用。     

腐乳感官和理化品质的核主成分分析

为解决PCA不适合多指标综合分析中非线性主成分分析的问题，采用核主成分分析(KPCA)方法，对我国不同地区16种腐乳的品质进行了综合评价。使用核函数将原空间映射到高维特征空间。在高维空间进行了线性主成分分析。结果表明。通过对核参数的适当选取。可使最大特征值的贡献率达到或接近85％。避免了多个主成分的不同组合而导致的评价结果的不一致。应用KPCA得到的腐乳品质的评价结果具有一定的客观性。     

Effects of Shenpang acupoint-stimulation on estrogen receptor immunoreactive neurons in thalamus of rabbits

To investigate the effects of Shenpang acupoint-stimulation in reproductive endocrinology, the changes in estrogen receptor immunoreactive (ER-IR) neurons after Shenpang acupoint-stimulation were studied by using immunohistochemistry. ER-IR positive reactions were detected in most nuclei of the thalamus. In the acupuncture-treated group, a great number of ER-IR positive neurons with clear dendrites existed in the nucleus, paraventricular nucleus, ventrolateral nucleus, ventromedial nucleus, ventroprincipal nucleus, centromedian nucleus, reticular nucleus, and periventricular nucleus of thalamus, and they were mainly located in the cytoplasm, nucleus and neutrite, and some also existed in the cytoplasmic membrane. In contrast, a few neurons existed in the above-mentioned nuclei in the control group, but they were slightly stained. It is concluded that Shenpang acupoint-stimulation can promote the expression of estrogen receptors in the above nuclei. Translated from Acta Veterinaria et Zootechnica Sinica, 2006, 37(1): 71–75 [译自: 畜牧兽医学报]     

兰科植物遗传图谱与QTL定位研究进展

兰科植物俗称兰花,是最重要的观赏花卉,构建遗传图谱,特别是高密度遗传图谱有助于提高育种水平,本研究主要对兰科植物遗传图谱与重要性状的QTL定位进行了综述。结果表明:1)2007年报道出兰科石斛属第一张遗传图谱以来,累计发表了13张兰科植物遗传连锁图谱。2)从图谱类型来看,5张为品种间图谱,8张为种间图谱;从图谱用途来分,7张可以用于QTL定位,3张可用于精细定位或基因克隆,另3张为基础参考图谱。3)从已构建的兰科植物遗传图谱看,总图距越来越高且平均图距越来越小,为图谱的实际应用奠定了基础,但作图群体较小始终是个问题。4)虽然在蝴蝶兰叶片、花色,石斛兰萼片大小及石斛茎及多糖含量等相关性状上进行了QTL定位,但在花朵大小、花朵数、花香、花型、花斑和植株抗性等方面均未涉及。因此,构建遗传图谱,特别是高密度遗传图谱能够为兰花的生物学研究及分子标记辅助育种提供参考依据。     

Eyes transplanted to tadpole tails send axons rostrally in two spinal-cord tracts

Axons from eyes transplanted to the tail in Xenopus larvae enter the caudal spinal cord and follow two adjacent tracts rostrally to the level of the cerebellum. When eyes are transplanted to the ear area, optic axons enter the hindbrain and follow the same tracts rostrally and caudally. These sensory pathways normally contain the embryonic sensory system of the Rohon-Beard axons and the descending and ascending tracts of nerve V. We propose that the transplanted optic axons have followed a continuous substrate sensory pathway normally shared by a number of different sensory tracts.