Effects of priming duration on retention over the first 1 1/2 years of life

Exposing individuals to an isolated component (a prime) of a prior event alleviates its forgetting. Two experiments with 120 human infants between 3 and 18 months of age determined the minimum duration of a prime that can reactivate a forgotten memory and how long the reactivated memory persists. Infants learned an operant task, forgot it, were exposed to the prime, and later were tested for renewed retention. In Experiment 1, the minimum duration of an effective prime decreased logarithmically with age, but was always longer than the duration of a mere glance. In Experiment 2, the reactivated memory was forgotten twice as fast after a minimum-duration prime as after a full-length one, irrespective of priming delay and infant age. These data reveal that the minimum effective prime duration psychophysically equates the accessibility of forgotten memories. We conclude that priming is perceptually based with effects that are organized on a ratio (log) scale.     

新生儿窒息史对儿童神经心理发育五项功能的影响

目的：分析有新生儿窒息史儿童五项神经心理发育测查结果，了解新生儿窒息对小儿神经心理发育的影响。方法：对有新生儿窒息史儿童98例分别于6月、12月、24月进行“小儿五项神经心理发育测查”，同时选择50例无新生儿窒息史、无其它重大疾病史儿童于相同月龄进行相同测量作对照，计算测得月龄与实际月龄的相差百分比平均值作标准化对比分析。结果：轻度窒息组57例与对照组无显著性差异，重度窒息组与对照组有显著性差异。结论：新生儿重度窒息对小儿五项神经心理发育有显著性影响。     

Embryonic development of four different subsets of cholinergic neurons in rat cervical spinal cord

The developmental stage at which a neuron becomes committed to a neurotransmitter phenotype is an important time in its ontogenetic history. The present study examines when choline acetyltransferase (ChAT) is first detected within each of four different subsets of cholinergic neurons previously identified in the cervical enlargement of the spinal cord: namely, motor neurons, partition cells, central canal cluster cells, and dorsal horn neurons. By examining the temporal sequence of embryonic development of these cholinergic neurons, we can infer the relationships between ChAT expression and other important developmental events. ChAT was first detected reliably on embryonic day 13 (E13) by both biochemical and immunocytochemical methods, and it was localized predominantly within motor neurons. A second group of primitive-appearing ChAT-positive cells was detected adjacent to the ventricular zone on E14. These neurons seemed to disperse laterally into the intermediate zone by E15, and, on the basis of their location, were tentatively identified as partition cells. A third group of primitive ChAT-immunoreactive cells was detected on E16, both within and around the ventral half of the ventricular zone. By E17, some members of this "U"-shaped group appeared to have dispersed dorsally and laterally, probably giving rise to dorsal horn neurons as well as dorsal central canal cluster cells. Other members of this group remained near the ventral ventricular zone, most likely differentiating into ventral central canal cluster cells. Combined findings from the present study and a previous investigation of neurogenesis (Phelps et al.: J. Comp. Neurol. 273:459-472, '88), suggest that premitotic precursor cells have not yet acquired the cholinergic phenotype because ChAT is not detectable until after the onset of neuronal generation for each of the respective subsets of cholinergic neurons. However, ChAT is expressed in primitive bipolar neurons located within or adjacent to the germinal epithelium. Transitional stages of embryonic development suggest that these primitive ChAT-positive cells migrate to different locations within the intermediate zone to differentiate into the various subsets of mature cholinergic neurons. Therefore, it seems likely that spinal cholinergic neurons are committed to the cholinergic phenotype at pre- or early migratory stages of their development. Our results also hint that the subsets of cholinergic cells may follow different migration routes. For example, presumptive partition cells may use radial glial processes for guidance, whereas dorsal horn neurons may migrate along nerve fibers of the commissural pathway. Cell-cell interactions along such diverse migratory pathways could play a role in determining the different morphological, and presumably functional, phenotypes expressed by spinal cholinergic neurons.     

Selective labeling of sensory hair cells and neurons in auditory, vestibular, and lateral line systems by a monoclonal antibody

This study reports that zn-1, a monoclonal antibody, labels hair cells but not supporting cells in the inner ear and the lateral line of the axolotl salamander, Ambystoma mexicanum. Zn-1 immunocytochemically labels the cytoplasm and stereocilia of mature hair cells in the sacculus, in the utriculus, and in the mechanoreceptive neuromast organs of the lateral line. Lower levels of labeling mark newly formed hair cells in the periphery of the sacculus and in regenerating neuromasts. Zn-1 also selectively labels neuronal processes and perikarya in the lateral line nerves and ganglia and the VIIIth cranial nerve and ganglion. Processes and perikarya are labeled by zn-1 in the dorsolateral medulla oblongata, at sites of termination of the afferent octaval and lateral line neurons. Western blot analysis revealed that zn-1 labels one or more proteins with molecular weights of 80 and 160 kDa. The identity of these protein bands remains to be determined. The presence of a specific epitope expressed in both hair cells and neurons, but not in supporting cells, in the vestibular and auditory epithelia of the ear and in the mechanoreceptive neuromasts of the lateral line suggests shared cytogenetic heritages. These findings are consistent with a close evolutionary relationship between otic and lateral line senses, such as that inherent to the theoretical evolutionary scheme outlined in van Bergeijk's "acousticolateralis hypothesis." The protein recognized by zn-1 is as yet unidentified, but its conservative evolution suggests that it may serve an important function in the statoacoustic and lateral line systems.     

Horizontal Interactions in Cat Striate Cortex: II. A Current Source-Density Analysis

The current source-density (CSD) analysis was used to investigate the organization of tangential synaptic connections in primary visual cortex of normally reared (NR) kittens and of NR, binocularly deprived (BD) and dark-reared (DR) adult cats. Laminar profiles of field potentials, elicited by intracortical microstimulation were measured at various distances from the stimulating electrodes. To exclude contamination by axon collaterals of antidromically stimulated thalamo-cortical fibres, these were destroyed by injecting the cytotoxin N-methyl-D-aspartate (NMDA) into the lateral geniculate nucleus 13 - 27 days before recording. The CSD profiles revealed distinct layer-specific patterns of lateral spread of activity. Invariably, the most prominent, long-lasting and far reaching responses were recorded in supragranular layers. Responses in layer IV were brief and confined to the vicinity of the stimulation site. Responses in infragranular layers spread as far as those in supragranular layers, but were of smaller amplitude. Latency considerations, the results of double shock stimulation, and the effects of translaminar cuts, suggest that these responses were monosynaptic and mediated by intracortical pathways with a conduction velocity of 0.3-5 m/s. The spatial spread of these responses changed substantially with age but was not influenced by visual deprivation. In NR adults, supra- and infragranular responses were recordable up to 2.5 mm from the stimulation site and layer IV responses up to 1 mm from the stimulation site. In kittens, the former responses spread up to 5 mm and the latter up to 2 mm from the site of stimulation. The amplitude of the responses decreased with distance from the stimulation site. This decrease was not always monotonic suggesting inhomogeneities in the tangential projections. The laminar distribution of current sinks and sources indicates that the pathways mediating tangential interactions form excitatory synapses on apical dendrites of pyramidal cells. It is concluded that the spatial spread of tangential excitatory interactions decreases with age, but that neither the laminar pattern nor the age-dependent reduction in the strength of tangential interactions are influenced by visual deprivation.     

不同细胞外基质在大鼠胚胎心脏中表达规律的比较

目的比较不同细胞外基质(ECM)及其共同基质受体在大鼠胚胎心脏中的表达规律,探讨ECM在胚胎期心脏发生、发育过程中的作用。方法将胎龄天数(ED)为11～19d的胚鼠用酶免疫组织化学染色检测ECM中的FN、LMN、Vn、CoⅣ及其受体β1在胚胎心脏中的表达。结果①ECM及其受体在胚胎各期心脏的空间性分布各不相同,FN及LMN有明显的空间分布互补关系,β1的空间分布主要与FN相似,但在空间隔及心外膜中又与LMN相似;②FN、LMN及β1在不同心脏部位的表达高峰及持续时间各不相同,β1的表达高峰要早于FN及LMN。结论ECM(主要是FN与LMN)及其受体β1在胚胎心脏的发生发育中起着一定的介导作用,其作用的时期、部位及作用机制各不相同。     

京剧嗓音的声学分析及音域特征

目的　从声学角度客观地检测京剧的嗓音特征 ,为京剧演唱者嗓音的训练和保护提供参考。方法　对 73名 1 6～ 5 7岁不同行当的专业京剧演员或学员 ,利用Dr Speech计算机频谱分析系统对元音 /a/、/i/歌唱舒适音和唱段进行声学参数的检测和分析。结果　各行当元音 /a/、/i/歌唱舒适音的基频 (fundamentalfrequency,F0 )分别是 :丑角 (2 72 6± 42 0 )Hz( x±s ,下同 )、(30 4 2± 2 2 1 )Hz;小生 (499 3± 34 0 )Hz,(485 4± 1 8 7)Hz;老生 (335 6± 6 0 0 )Hz,(31 7 9± 45 1 )Hz ;花脸 (31 9 0±6 1 3)Hz,(34 0 1± 6 8 8)Hz;老旦 (42 7 6± 47 2 )Hz,(437 7± 45 8)Hz ;花旦 (5 35 8± 48 8)Hz,(5 6 1 6± 2 9 2 )Hz ;青衣 (5 48 0± 6 9 5 )Hz,(5 43 5± 79 3)Hz;其它声学参数 :频率微扰 (pitchperiodperturbation,或Jitter)、振幅微扰 (amplitudeperturbation ,或Shimmer)和声门噪声能量 (也称标准化噪声能量级 ,normalizednoiseenergy ,NNE)均在软件提供的正常值范围内 ;京剧演员歌唱音域的跨度为 1 7～ 2 8个八度 ,最低音和多数最高音均比西洋唱法的高音声部相应的值高。结论　京剧嗓音有着独特的声学特征 ;结果对其嗓音的训练和保护有一定的临床参考     

The development of the stria vascularisin the human foetus

The development of the stria vascularis in the human cochlea was studied in step sections of 81 human foetal temporal bones. The stria vascularis primordium can be identified as a ridge of epithelial cells on the lateral wall of the cochlear duct. The first signs of differentiation appear at the 11th week, but it is not until the 17th–18th week that the typical trilaminar structure is observed. The appearance of similar cells with notched nuclei in both marginal and mesenchymal layers at this stage suggests the possibility that some of the intermediate cells may be of epithelial origin. By the 21st week, the overall appearance resembles that of the adult structure. This occurs 1week after the opening of the tunnel of Corti, and possibly marks the onset of cochlear function.     

医学院校多媒体教育校园网的模式与管理

本文对校园网的教学应用范围、两种组成模式作了简要的介绍,指出校园网的快速建设和发展,对教学、科研、建立新的教学模式、改革教学内容、方法、推进素质教育等方面起到了积极重要的作用,离不开管理层观念的转变及长期支持。并对网络软件资源开发、建设、管理进行了建设性的讨论。     

NMDA受体与NOS在大鼠脊髓中间外侧柱的定位和生后发育

目的 探讨N-甲基-天冬氨酸受体（NMDAR1和NMDAR2A/B亚基）、一氧化氮合酶（NOS）及还原型辅酶Ⅱ硫辛酰胺脱氢酶（NADPH-d）活性在大鼠脊髓中间外侧柱（IML）的定位与生后发育特征。方法 在甲醛固定的脊髓切片上,进行ABC法免疫染色和NADPH-d组织化学反应与半定量分析。结果 MMDAR1,NMDAR2A/B,NOS I和NADPH-d反应产物丰富地分布于IML,主要定位于神经元胞体、树突和轴突样纤维终末。在生后早期发育中它们具有明显的动态变化,生后7d(P7）有微弱或中等的表达,随后逐渐上调,P21或P28达到高峰,然后保持于此水平于成体动物。结论 NMDA受体-NO通路可能是脊髓交感节前神经元一条重要的细胞内信号途径,并参与神经元生后发育成熟的调控过程。