大鼠扣带回——丘脑腹侧基底核投射的HRP研究

用ＨＲＰ逆行示踪法证实了大鼠扣带回前部－－丘脑腹侧基底核投射通路。当ＨＲＰ注入丘脑腹侧基底核时,在同侧扣带回前部观察到标记的细胞,标记细胞密度背侧区比腹侧区高。上述结果表明扣带回前部神经元直接投射到同侧丘脑腹侧基底核,且背侧区的投射密度较大。     

蛤蚧圆核-前背侧室嵴通路研究

运用ＨＲＰ逆行标记技术,对蛤蚧（Ｇｅｋｋｏ ｇｅｃｋｏ）离顶盖通路中丘脑圆核（Ｒｔ）到端脑前背侧室嵴（ＡＤＶＲ）投射的具体模式和局部相关性进行研究。结果显示：蛤蚧丘脑Ｒｔ前、中部的腹外侧区传出纤维,沿外侧前脑束（ｌｆｂ）前行至前联合（ｃａ）,少数纤维交叉至对侧,多数仍同侧前行,末梢到达ＡＤＶＦ嘴外侧区核心部,投射模式为双侧投射。     

蛤蚧前背侧室嵴嘴外侧区的投射研究

本文运用HRP顺、逆行追踪技术,对蛤蚧（Gekko gecko)前背侧室嵴（ADVR）嘴外侧区纤维联系进行了研究。结果表明,ADVR嘴外侧区核心部的传入纤维来自双侧丘脑园核（Rt)前、中部的腹外侧区;ADVR嘴外侧区与尾部在室周带中有广泛分布的环路存在;ADVR嘴外侧区核心部－皮层加厚区环路是联系两条视觉通路的桥梁。     

工作记忆编码腹侧海马和内侧前额叶皮层局部场电位信号的相位同步分析

研究比较大鼠在静息状态下和工作记忆编码阶段腹侧海马和内侧前额叶皮层局部场电位相位同步的变化,分析相位在工作记忆任务相关信息处理中的作用机制。研究数据为6只SD大鼠静息状态和执行Y迷宫空间工作记忆任务时采集的腹侧海马和内侧前额叶皮层的局部场电位信号,计算两个脑区局部场电位信号之间的加权相位滞后指数值。研究结果表明,与静息状态相比,在工作记忆编码阶段,腹侧海马和内侧前额叶皮层之间的相位同步性在theta频段选择性地并且显著性地增加。腹侧海马和内侧前额叶皮层theta频段的相位同步是工作记忆编码阶段任务信息处理的一个作用机制。     

额叶皮层损伤对大鼠基底前脑胆硷能神经元的影响

为探讨前额叶皮层局限性损伤对大鼠学习、记忆功能及基底前脑胆硷能神经元的影响。用外科手术造成大鼠 1侧前额叶皮层局限性损伤后不同时间 ,用Y型迷宫检测学习、记忆功能 ,用组织化学技术检测基底前脑含乙酰胆硷酯酶 (AchE)活性神经元。结果为前额叶皮层损伤后 1周 ,动物学习、记忆功能有所障碍 ,损伤同侧的基底前脑胆硷能神经元有所减少 ,但均无统计学意义。损伤后 2、3、4周 ,动物学习、记忆障碍明显 ,损伤同侧基底前脑胆硷能神经元明显减少 (P <0 .0 5) ,且两者变化相平行。结论为单侧前额叶皮质局限性损伤不仅可引起动物学习、记忆功能障碍 ,且可引起同侧基底前脑胆硷能神经元丢失 ,两者发展且相平行 ,提示基底前脑胆硷能神经元逆行性变性在动物额叶皮层损伤引起的学习、记忆障碍中起作用。     

电刺激大鼠mPFC对听皮层神经元听反应的影响

实验在40只成年SD大鼠上进行,使用常规电生理学方法,观察了电刺激大鼠内侧额叶前皮质(medial prefrontal cortex, mPFC)对听皮层神经元听反应的影响.在122个神经元上观察了电刺激mPFC对听反应的影响.对其中93个神经元作了详细分析发现,有73个神经元的听反应受到易化（39个,41.9%）或抑制（34个,36.6%）.刺激mPFC对听反应的影响存在最佳刺激间隔,大多数神经元（51个,69%）在10~15 ms之间.结果提示,大鼠mPFC可对听皮层神经元的听反应调制,这种调制可能是通过多级神经元环路实现的.     

卡龙游仆虫(Euplotes charon)无性分裂期间皮层结构分化的研究

利用蛋白银、孚尔根和银浸等染色方法对分类上有争议的 E.charon的形态结构和无性分裂过程中皮层的发育分化进行了研究 .E. charon表面有额腹、横、尾部棘毛 10、 5、 4根,背触毛 12列,大核倒“ C”形,小核球形 .E. charon在无性分裂过程中,皮层的纤毛器官多由相应原基发育而成（前仔虫的口围带、口侧膜由老口改组后承继下来） .     

运动疲劳大鼠丘脑腹外侧核神经元自发放电特征的分析

通过观察力竭运动对大鼠丘脑腹外侧核(VL)神经元自发放电活动的影响,探讨丘脑腹外侧核在运动疲劳中枢调控过程中的作用.选取雄性Wistar大鼠,随机分为对照组和疲劳组.采用跑台递增负荷运动方案,建立运动疲劳模型.采用玻璃微电极的体电生理学技术,观察丘脑腹外侧核神经元自发放电活动,并对其放电模式、放电频率、锋电位间隔直方图进行线下分析.得到了FG大鼠丘脑腹外侧核单簇发混合放电和规则单发放电神经元比例明显低于CG(P0.01),爆发式放电神经元比例明显高于CG(P0.01).FG大鼠丘脑腹外侧核神经元总放电频率显著低于CG(P0.05),规则单发放电频率有所升高,单簇发混合放电频率有所降低,但与CG相比均未见显著差异(P0.05).可以看出大鼠丘脑腹外侧核神经元参与了运动性疲劳的中枢调控.丘脑腹外侧核在运动疲劳引起间接通路与直接通路的调节功能失衡过程中起关键作用.     

鸽丘间复合体背内侧核传出投射－CTB－HRP法

用ＣＴＢ—ＨＲＰ顺行示踪法，对鸽中脑丘间复合体背内侧核（ＤＭ）的传出投射进行了研究．结果发现，顺行终末标记出现在下列脑干部位：脑桥臂旁核腹外侧（ＰＢｖｌ）、延髓喙端腹外侧（ＲＶＬ）、舌下神经核气管鸣管亚核（ｎⅫｔｓ）疑核（ｎＡｍ）、后疑核（ｎＲＡｍ）．这些标记以同侧为主．对侧ＤＭ亦发现顺行终末标记．这些结果提示，ＤＭ兼有发声控制与呼吸调节的双重功能．     

黄雀(Carduelis spinus)上橄榄核的传入性联系—HRP顺逆行追踪法研究

分别将HRP微电泳入黄雀的上橄榄核(SO)、角状核、层状核和巨细胞核,观察其顺、逆行标记物的分布.结果表明,SO接受同侧层状标和双侧角状核的传入,双侧SO之间有交互投射,SO的纤维投射至外侧丘系核腹侧部、外侧丘系腹核和中脑背外侧核.因此,它属于听觉传入通路中的第二级中继站.此外,SO向巨细胞核投射并形成巨细胞核→层状核→SO→巨细胞核的闭合环路.此环路可能参与听觉信息的反馈及声源定向等的初步整合机能.     

Guarding the gateway to cortex with attention in visual thalamus

The massive visual input from the eye to the brain requires selective processing of some visual information at the expense of other information, a process referred to as visual attention. Increases in the responses of visual neurons with attention have been extensively studied along the visual processing streams in monkey cerebral cortex, from primary visual areas to parietal and frontal cortex. Here we show, by recording neurons in attending macaque monkeys (Macaca mulatta), that attention modulates visual signals before they even reach cortex by increasing responses of both magnocellular and parvocellular neurons in the first relay between retina and cortex, the lateral geniculate nucleus (LGN). At the same time, attention decreases neuronal responses in the adjacent thalamic reticular nucleus (TRN). Crick argued for such modulation of the LGN by observing that it is inhibited by the TRN, and suggested that "if the thalamus is the gateway to the cortex, the reticular complex might be described as the guardian of the gateway", a reciprocal relationship we now show to be more than just hypothesis. The reciprocal modulation in LGN and TRN appears only during the initial visual response, but the modulation of LGN reappears later in the response, suggesting separate early and late sources of attentional modulation in LGN.     

Lack of regional specificity for connections formed between thalamus and cortex in coculture

The mammalian cerebral cortex consists of many structurally and functionally specialized areas, with characteristic input from particular nuclei of the thalamus. Some localized external influence, such as the arrival of fibres from the appropriate thalamic nucleus before or around the time of birth, could trigger the emergence of committed cortical fields from an undifferentiated 'protocortex. The guidance of axons from each thalamic nucleus to its appropriate target area in the cortex could, then, be crucial in the regulation of cortical differentiation. Recently, Yamamoto et al. and Bolz et al. have demonstrated that cocultured explants of rat lateral geniculate nucleus and visual cortex can form layer-specific interconnections. We have now tested the possibility that each cortical area exerts a selective trophic influence on axons from its appropriate thalamic nucleus, and vice versa, by coculturing explants of different regions of the thalamus and cortex taken at various stages of development. Although thalamo-cortical and cortico-thalamic connections formed in vitro can be remarkably normal in many respects, they lack regional specificity.     

Feedback inhibition controls spike transfer in hybrid thalamic circuits

Sensory information reaches the cerebral cortex through the thalamus, which differentially relays this input depending on the state of arousal. Such 'gating' involves inhibition of the thalamocortical relay neurons by the reticular nucleus of the thalamus, but the underlying mechanisms are poorly understood. We reconstructed the thalamocortical circuit as an artificial and biological hybrid network in vitro. With visual input simulated as retinal cell activity, we show here that when the gain in the thalamic inhibitory feedback loop is greater than a critical value, the circuit tends towards oscillations -- and thus imposes a temporal decorrelation of retinal cell input and thalamic relay output. This results in the functional disconnection of the cortex from the sensory drive, a feature typical of sleep states. Conversely, low gain in the feedback inhibition and the action of noradrenaline, a known modulator of arousal, converge to increase input output correlation in relay neurons. Combining gain control of feedback inhibition and modulation of membrane excitability thus enables thalamic circuits to finely tune the gating of spike transmission from sensory organs to the cortex.     

Formation of target-specific neuronal projections in organotypic slice cultures from rat visual cortex.

A characteristic feature of the mammalian cortex is that projection neurons located in distinct cortical layers send their axons to different targets. In visual cortex, cells in layers 2 and 3 project to other cortical areas, whereas cells in layers 5 and 6 project to subcortical targets such as the lateral geniculate nucleus. The proper development of these projections is crucial for correct functioning of the visual system. Here we show that specific connections are established in an organotypic culture system in which rat visual cortex slices are co-cultured with another slice of the visual cortex or with a thalamic slice. The laminar origin and cellular morphology in vitro of cortical projections to other cortical regions or to subcortical targets are remarkably similar to those seen in vivo. In addition, axons of projecting cells are not restricted to particular pathways, but appear instead to grow directly towards their appropriate target. These observations raise the possibility that chemotropic attraction from the target areas may play an important part in the development of the cortical projection pattern.     

鸣禽间脑听觉卵圆核壳区脑啡肽的免疫组织化学？…

应用尼氏染色及脑啡肽免疫组织化学方法研究了鸣禽白腰文鸟（Ｌｏｎｃｈｕｒａ ｓｔｒｉａｔａ）间脑听觉中－卵圆核（ｎ．Ｏｖｏｉｄａｌｉｓ Ｏｖ）中心核及其壳区（ｓｈｅｌｌ）的形态学特征,再应用神经示踪剂ＢＤＡ（ｂｉｏｔｉｏｎｙｌａｔｅｄ ｄｅｘｔｒａｎ ａｍｉｎｅ）对壳区的神经投射了研究,结果发现（１）脑啡肽免疫组织方法尼氏染色更能区分中心核及壳区,仅Ｏｖ壳区存在脑啡肽纤维或细胞,而忠订户站不存在;     

鸣禽间脑听觉卵圆核壳区脑啡肽的免疫组织化学及神经联系

应用尼氏染色及脑啡肽免疫组织化学方法研究了鸣禽白腰文鸟(Lonchura striata)间脑听觉中继核--卵圆核(n. Ovoidalis Ov)中心核及其壳区(shell)的形态学特征,再应用神经示踪剂BDA (biotionylated dextran amine)对壳区的神经投射进行了研究.结果发现: (1) 脑啡肽免疫组织化学方法较尼氏染色更能区分中心核及壳区,仅Ov壳区存在脑啡肽纤维或细胞,而中心核几乎不存在;(2) Ov 壳发出纤维投向端脑听区L2b, L1 ,L3,下丘脑腹内侧核(ventromedial nucleus VMN)和下丘脑前内侧核(n. anterior medialis hypothalami AM); (3) Ov壳接受端脑古纹状体粗核(robust archistriatum RA)壳区、中脑背内侧核(mesencephalicus lateralis pars dorsalis MLd)与丘间核(n. intercollicularis ICo)界面区的投射.首次发现鸣禽卵圆核壳区同非鸣禽相似,也与下丘脑有神经投射联系,它为听觉发声引起内分泌活动及有关行为的改变提供了神经结构基础.     

Retrospective and prospective coding for predicted reward in the sensory thalamus

Reward is important for shaping goal-directed behaviour. After stimulus-reward associative learning, an organism can assess the motivational value of the incoming stimuli on the basis of past experience (retrospective processing), and predict forthcoming rewarding events (prospective processing). The traditional role of the sensory thalamus is to relay current sensory information to cortex. Here we find that non-primary thalamic neurons respond to reward-related events in two ways. The early, phasic responses occurred shortly after the onset of the stimuli and depended on the sensory modality. Their magnitudes resisted extinction and correlated with the learning experience. The late responses gradually increased during the cue and delay periods, and peaked just before delivery of the reward. These responses were independent of sensory modality and were modulated by the value and timing of the reward. These observations provide new evidence that single thalamic neurons can code for the acquired significance of sensory stimuli in the early responses (retrospective coding) and predict upcoming reward value in the late responses (prospective coding).     

Induction of functional retinal projections to the somatosensory system

Optic axons can be induced to form permanent, retinotopic connections in the auditory (medial geniculate, MG) and somatosensory (ventrobasal, VB) nuclei of the Syrian hamster thalamus; this occurs when the principal targets of retinofugal axons are ablated in newborn hamsters and alternative terminal space is created by partial deafferentation of MG or VB. The experimentally induced retinal projection to the somatosensory nucleus occurs by the stabilization of an early, normally transient projection. The present study was undertaken to determine whether the anomalous, stabilized retino-VB projection is functional. Newborn hamsters were operated on to produce permanent retino-VB projections and when the animals were mature, neurophysiological recordings were made in the cortical targets of VB, the first and second somatosensory cortices (SI and SII, respectively). Visual stimulation within well-defined receptive fields reliably evoked multi-unit responses in SI and SII of operated, but not normal hamsters. The representations of the visual field in SI and SII showed a partially retinotopic organization. These results demonstrate that optic tract axons can form functional synapses in the thalamic somatosensory nucleus, and suggest that neural structures which normally process information specific to one sensory modality have the potential to mediate function for other modalities.     

Gain control by layer six in cortical circuits of vision

After entering the cerebral cortex, sensory information spreads through six different horizontal neuronal layers that are interconnected by vertical axonal projections. It is believed that through these projections layers can influence each other's response to sensory stimuli, but the specific role that each layer has in cortical processing is still poorly understood. Here we show that layer six in the primary visual cortex of the mouse has a crucial role in controlling the gain of visually evoked activity in neurons of the upper layers without changing their tuning to orientation. This gain modulation results from the coordinated action of layer six intracortical projections to superficial layers and deep projections to the thalamus, with a substantial role of the intracortical circuit. This study establishes layer six as a major mediator of cortical gain modulation and suggests that it could be a node through which convergent inputs from several brain areas can regulate the earliest steps of cortical visual processing.