鸣禽中脑听觉核团边缘区神经投射的研究

对鸣禽白腰文鸟(Lonchura striata)中脑听觉核团--背外侧核(nucleus mesencephalicus lateralis, pars dorsalis, MLd) 和丘间核(nucleus intercollicularis, ICo)的脑啡肽免疫化学特性和神经联系进行了研究.结果发现:脑啡肽能标记纤维或细胞主要分布于中脑听觉核团的背外侧核边缘区、丘间核,而背外侧核中央区几乎无分布.双向神经示踪剂生物素结合的葡聚糖胺注射入MLd边缘区后,从端脑到延髓的许多核团或脑区均获得了传出传入神经标记.MLd边缘区接受5个核团或脑区的投射,即:端脑古纹状体粗核(robust archistriatum, RA)壳区、下丘脑视前核(nucleus p reopticus anterior, POA)、脑桥臂旁核(nucleus parabrachialis ventrolateralis, PBv l)、延髓下橄榄上核(nucleus infraolivaris superior,IOS)和延髓喙腹外侧核(nucleus r ostral ventrolateral medulla, RVL); 而MLd边缘区发出纤维,支配间脑卵圆核(nucleus ovoidalis, Ov)壳区和外侧下丘脑(nucleus lateralis hypothalami,LHy).结果提示鸣禽中脑背外侧核边缘区在听觉发声、内分泌活动及其他生理活动的联系中可能具有重要作用.     

丘脑底核电刺激对癫痫大鼠模型基底节神经元放电的影响

目的应用不同频率的电刺激海人酸模型癫痫大鼠STN核,观察STN核以及SNr(黑质网状部)神经元细胞在刺激后放电频率的变化,研究电刺激STN对STN内神经元和SNr神经元放电的影响,探讨STN-DBS治疗癫痫的作用机制。方法10只癫痫大鼠为实验组,另10只正常大鼠作为对照组。参照大鼠立体定向图谱,将记录的玻璃微电极和刺激电极分别插入STN、SNr核团内,刺激频率分为三组,分别为30 Hz、130 Hz、260 Hz。通过单神经元放电细胞外记录方法分别于高频刺激前后记录脑内核团神经元放电情况,分析神经元在STN-HFS刺激前和刺激时放电改变情况。结果正常大鼠的STN及SNr神经元放电与癫痫模型大鼠相比,两者放电频率不存在显著性差异,对放电模式的分析发现两者也无明显差异(P>0.05)。癫痫大鼠的STN及SNr神经元在30 Hz的刺激过程中放电频率多数没有明显变化。随着放电频率的增加两种神经元在电刺激后多数神经元放电明显受到抑制。在130 Hz和260 Hz组,受抑制的神经元较30 Hz组明显增加,具有显著性差异(P<0.05)。结论本研究证实高频电刺激STN明显抑制了STN和SNr神经元的兴奋性,其效果与频率是相...     

神经性厌食症大鼠伏隔核神经元电活动及峰峰间期序列的分析

目的观察神经性厌食症大鼠模型伏隔核神经元的电活动并分析其峰峰间期。方法通过微阵列电极记录大鼠在神经性厌食症病理及正常生理状态下伏隔核神经元的自发放电活动。结果电生理记录显示模型组大鼠NAc神经元平均放电频率为6.89±2.67Hz,对照组大鼠NAc神经元平均放电频率为3.22±1.23Hz。(P=0.001)。模型组大鼠伏隔核神经元放电的峰峰间期散点图在200ms以下有密集分布。模型组伏隔核神经元放电峰峰间期直方图呈逐渐衰减的正偏态分布,对照组伏隔核神经元放电峰峰间期直方图呈对称分布。结论神经性厌食症模型大鼠伏隔核神经元较生理状态下放电频率明显增加,峰峰间期序列发生明显变化。     

扭转痉挛患者基底节的电生理研究

目的 观察扭转痉挛患者基底节神经元的电活动特点。方法 在对6例扭转痉挛患者行微电极导向脑内核团毁损术治疗的同时,利用微电极记录技术分别对4例患者的内苍白球、2例患者的丘脑底核神经元电活动进行了记录和分析。结果 内苍白球神经元主要表现为高度不规律的持续低频群发放电,间有暂歇,其平均自发放电频率为(26.4±13.9)Hz,电活性较低。丘脑底核神经元主要表现为不规律的发放,其平均自发放电频率为(49.1±9.2)Hz,电活性较高。结论 扭转痉挛患者基底节存在功能异常。     

帕金森病大鼠苍白球神经元簇发放电及峰峰间期序列的研究

目的 观察帕金森病大鼠模型苍白球神经元的电活动.方法 30只大鼠注射6-羟基多巴胺(6-hydroxydopamine, 6-OHDA)建立PD模型,并通过跑步机测试、注射阿朴吗啡诱发旋转和免疫组化检测黑质对模型进行评价;10只大鼠注射含0.2%抗坏血酸的人工脑脊液建立对照组.在立体定向仪引导下记录大鼠在PD病理及正常生理状态下GP神经元的自发放电活动.结果 模型组大鼠中有13只行为学及病理学检测结果符合PD模型标准.电生理记录显示对照组大鼠GP神经元放电频率为(6.04±2.12)Hz,模型组大鼠GP神经元放电频率为(21.10±3.21)Hz(P=0.001).模型组GP神经元簇发放电模式的比例术后4周为59%,术后8周为61%,而对照组GP神经元簇发放电模式的比例在术后4周和8周均为11%.模型组大鼠神经元放电的峰峰间期散点图在100ms以下有一分布密集条带.结论 PD模型大鼠GP神经元较生理状态下放电频率明显增加,簇状放电模式比例增大,ISI序列发生明显变化.     

何首乌对海人藻酸致大鼠脑 AChE神经元及纤维损伤的保护作用

目的　观察海人藻酸 (KA)对大鼠基底前脑含乙酰胆碱能神经元 (包括其投射纤维投射部位 )毁损后的数目和形态改变 ,以探讨何首乌 (PMT)对胆碱能神经元及其纤维的保护作用及机制。方法　采用兴奋性神经毒素海人藻酸 (KA)损伤基底前脑 (BF)Meynert核团 ,内侧隔核 (MS)及斜角带核 (DB) ,建立毁损模型 ,用何首乌喂饲毁损实验组 ,使用组织化学方法显示乙酰胆碱能神经元及纤维的改变及可能的用药后保护和活化作用。结果　何首乌喂饲组 (A组 )比非何首乌喂饲组 (B组 )在基底前脑中的Meynert核数量多 ,且细胞完整无破坏 ,其投射到海马及大脑皮质的AChE纤维数目多 ,纤维形态无破坏 ,差异有显著性 (P <0 .0 1)。结论　何首乌对大鼠AChE神经元及其投射纤维有保护作用。     

帕金森病猴丘脑底核神经元的电生理特性

目的探讨帕金森病(PD)猴模型丘脑底核(STN)神经元的电生理特性,为研究帕金森病的病理生理过程提供动物实验依据。方法应用颈内动脉注射MPTP建立PD猴模型。在立体定向仪引导下应用细胞外记录的方法记录"造模"前后猴病理及正常生理状态下STN神经元的放电活动,并对其放电模式进行分析。结果电生理记录显示STN神经元放电频率在生理状态下为2.03±1.12Hz;在病理状态下为9.58±0.85 Hz(P<0.01)。在生理状态下有20个(20/35,57.14%)神经元呈现簇发放电,有15个(15/35,42.86%)神经元呈现连续放电;在PD病理状态下有10个(10/12,85.71%)神经元呈现簇发放电,有2个(2/12,14.29%)神经元呈现连续放电(P<0.05)。生理状态下STN神经元的ISI序列散在分布于30～980ms之间;在PD病理状态下当STN神经元呈连续放电时,ISI分布于50～360ms之间,在150ms以下有一个分布密集条带,当STN神经元呈簇发放电时,ISI分布于30～470ms之间,在40ms以下有一个分布密集条带。结论PD猴模型STN神经元较生理状态下放电频率明显增加,其放电模式也有明显变化,簇状放电模式比例增大,ISI序列发生明显变化。     

帕金森病大鼠苍白球神经元放电模式的分析

目的 探讨帕金森病(Parkinson's disease,PD)大鼠苍白球(globus pallidus,GP)神经元的放电模式,为研究帕金森病的病理生理过程提供实验依据.方法 大鼠30只,应用6-羟基多巴胺(6-hydroxydopamine,6-OHDA)建立PD大鼠模型(模型组),多种方法对模型进行评价.在立体定向仪引导下记录PD模型组及正常生理状态下大鼠(对照组,10只)GP神经元放电活动,并对其放电模式进行分析.结果 模型组大鼠中有13只行为学及病理学检测结果符合PD模型标准.电生理记录显示对照组大鼠GP神经元放电频率为6±2Hz,模型组大鼠GP神经元放电频率为21±3Hz,模型组大鼠的放电频率显著高于对照组(P＜0.05).对照组共记录到四种形式的放电模式,模型组记录到三种.对照组GP神经元簇发放电模式的比例为11%,而模型组GP神经元簇发放电模式的比例术后四周为59%,术后八周为61%,两者比较具有统计学意义(P＜0.05).结论 PD模型大鼠GP神经元较生理状态下放电频率明显增加,其放电模式也有明显变化,簇状放电模式比例增大.这可能在帕金森病的病理生理变化中具有重要作用.     

神经性厌食症大鼠伏隔核神经元局部场电位分析

目的观察神经性厌食症大鼠模型伏隔核神经元的电活动并分析其局部场电位。方法实验动物分为运动诱发的厌食症(activity-based anorexia,ABA)大鼠模型组及对照组(各12只)。ABA模型的建立基础是模型大鼠不受限制的滚轮运动以及限制饮食(1h/d),通过这种限制饮食及过度活动,造成明显的体重下降,从而模拟AN的行为学特征。通过微阵列电极记录大鼠在神经性厌食症病理及正常生理状态下伏隔核神经元的局部场电位。结果电生理记录显示模型组大鼠NAc神经元平均放电频率为(6.89±2.67)Hz,对照组为(3.22±1.23)Hz。模型组大鼠伏隔核神经元放电的峰峰间期散点图在200ms以下有密集分布。模型组伏隔核神经元放电峰峰间期直方图呈逐渐衰减的正偏态分布,对照组伏隔核神经元放电峰峰间期直方图呈对称分布;回归映射分析结果显示病理状态下数据明显较生理状态下集中。功率谱密度分析显示模型组在10~20Hz范围内出现了能量高值成分。结论神经性厌食症模型大鼠伏隔核神经元较生理状态下放电频率明显增加,峰峰间期序列发生明显变化,局部场电位模式发生变化。     

神经肽Y对海马神经元兴奋性突触活动的影响

目的观察神经肽Y(NPY)对体外培养海马神经元兴奋性突触活动的影响。方法 Wistar大鼠海马神经元体外原代培养,无镁细胞外液处理3h,建立稳定的海马神经元癫痫样放电模型,应用全细胞膜片钳记录技术,观察不同浓度NPY对海马神经元自发兴奋性突触后电流(sEPSCs)的影响。结果 (1)体外培养12d的海马神经元轮廓清晰,折光性良好,彼此间广泛突触联系形成,适于神经元电生理试验。(2)癫痫组神经元sEPSCs发放频率(28.826±1.254HZ)高于对照组(1.296±0.241HZ),差异有统计学意义(P<0.05)。0.1μmol NPY组sEPSCs的频率为0.895±0.146HZ;1μmol NPY组频率为0.461±0.394HZ,与癫痫组(28.826±1.254HZ)相比,均有明显降低,差异有统计学意义(P<0.05)。0.1μmol NPY组的频率降低的程度小于1μmol NPY组神经元,差异有统计学意义(P<0.05)。sEPSCs幅度各组相比无明显差异(P>0.05)。结论 NPY能够抑制癫痫神经元sEPSCs的频率,而不影响幅度,这为NPY基因治疗癫痫提供了电生理学证据。     

SK channels modulate the excitability and firing precision of projection neurons in the robust nucleus of the arcopallium in adult male zebra finches

Objective Motor control is encoded by neuronal activity. Small conductance Ca2+-activated K+ channels (SK channels) maintain the regularity and precision of firing by contributing to the afterhyperpolarization (AHP) of the action potential in mammals. However, it is not clear how SK channels regulate the output of the vocal motor system in songbirds. The premotor robust nucleus of the arcopallium (RA) in the zebra finch is responsible for the output of song information. The temporal pattern of spike bursts in RA projection neurons is associated with the timing of the acoustic features of birdsong. Methods The firing properties of RA projection neurons were analyzed using patch clamp whole-cell and cell-attached recording techniques. Results SK channel blockade by apamin decreased the AHP amplitude and increased the evoked firing rate in RA projection neurons. It also caused reductions in the regularity and precision of firing. RA projection neurons displayed regular spontaneous action potentials, while apamin caused irregular spontaneous firing but had no effect on the firing rate. In the absence of synaptic inputs, RA projection neurons still had spontaneous firing, and apamin had an evident effect on the firing rate, but caused no significant change in the firing regularity, compared with apamin application in the presence of synaptic inputs. Conclusion SK channels contribute to the maintenance of firing regularity in RA projection neurons which requires synaptic activity, and consequently ensures the precision of song encoding.     

Neural correlates of female song in tropical duetting birds

Duetting involves production of song by female and male birds in close temporal coordination. We studied the neural network controlling song in 3 tropical duetting species. The volumes of song control regions (SCRs) in the brain, neuronal density in nucleus robustus of the archistriatum (RA) which is one of these SCRs, total number of neurons in RA, and somal size of neurons in RA were measured and compared to values published for zebra finches and canaries in which only males sing. The extent of sexual dimorphism in SCR volumes, RA neuronal density, and total neuronal number in RA varied in a graded fashion across species and was correlated with extent of sexual dimorphism in song repertoire size in any one species. Somal size of RA neurons was identical in males and females of each duetting species, regardless of relative repertoire size. Of all SCRs, the caudal nucleus of the ventral hyperstriatum appeared to have the greatest relative size in the song system of duetting birds compared to non-duetting species.     

Reorganization of a telencephalic motor region during sexual differentiation and vocal learning in zebra finches

Male zebra finches learn to produce a vocal pattern during a sensitive period of development, whereas females do not. The motor output of telencephalic song processing is RA (the robust nucleus of the archistriatum), a region containing a population of projection neurons that descend to the hindbrain (nXIIts, the tracheo-syringeal portion of the hypoglossal nerve nucleus). In turn, nXIIts neurons innervate the vocal organ (syrinx). Previous work shows that the number of RA neurons is monomorphic in fledgling males and females. RA neuron number in males does not change thereafter, but females show a substantial developmental loss of RA neurons. Because the developmental sex difference in RA neuron number implies a change in the number of projection neurons within RA, we have made injections of retrograde tracer into the hindbrain to measure the percentage of RA neurons that project to nXIIts as a function of age in females and vocal development in males. In juveniles of both sexes, we found that close to two-thirds of RA neurons project to nXIIts. However, the percentage of RA neurons projecting to nXIIts declined by 44% during female development, and by 14% during a specific stage of male vocal development (the transition from subsong to plastic song). These data indicate that in addition to regulation of RA neuron number, sexual differentiation and vocal learning correlate with a significant decrease in the amount of descending input to the vocal organ. The loss of projection neurons during vocal learning is surprising in light of the stability of RA neuron number in males, and our findings suggest that the behavioral transition from subsong to plastic song may involve a restricted period of RA neuron loss and replacement and/or axon rearrangement.     

Morphological characterization of HVC projection neurons in the zebra finch (Taeniopygia guttata)

Singing behavior in the adult male zebra finch is dependent upon the activity of a cortical region known as HVC (proper name). The vast majority of HVC projection neurons send primary axons to either the downstream premotor nucleus RA (robust nucleus of the arcopallium, or primary motor cortex) or Area X (basal ganglia), which play important roles in song production or song learning, respectively. In addition to these long‐range outputs, HVC neurons also send local axon collaterals throughout that nucleus. Despite their implications for a range of circuit models, these local processes have never been completely reconstructed. Here, we use in vivo single‐neuron Neurobiotin fills to examine 40 projection neurons across 31 birds with somatic positions distributed across HVC. We show that HVC_(RA) and HVC_(X) neurons have categorically distinct dendritic fields. Additionally, these cell classes send axon collaterals that are either restricted to a small portion of HVC (“local neurons”) or broadly distributed throughout the entire nucleus (“broadcast neurons”). Overall, these processes within HVC offer a structural basis for significant local processing underlying behaviorally relevant population activity.     

In vivo dynamic ME-MRI reveals differential functional responses of RA- and area X-projecting neurons in the HVC of canaries exposed to conspecific song

HVC (nidopallial area, formerly known as hyperstriatum ventrale pars caudalis), a key centre for song control in oscines, responds in a selective manner to conspecific songs as indicated by electrophysiology. However, immediate-early gene induction cannot be detected in this nucleus following song stimulation. HVC contains neurons projecting either towards the nucleus robustus archistriatalis (RA; motor pathway) or area X (anterior forebrain pathway). Both RA- and area X-projecting cells show auditory responses. The present study analysed these responses separately in the two types of HVC projection neurons of canaries by a new in vivo approach using manganese as a calcium analogue which can be transported anterogradely and used as a paramagnetic contrast agent for magnetic resonance imaging (MRI). Manganese was stereotaxically injected into HVC and taken up by HVC neurons. The anterograde axonal transport of manganese from HVC to RA and area X was then followed by MRI during approximately 8 h and changes in signal intensity in these targets were fitted to sigmoid functions. Data comparing birds exposed or not to conspecific songs revealed that song stimulation specifically affected the activity of the two types of HVC projection neurons (increase in the sigmoid slope in RA and in its maximum signal intensity in area X). Dynamic manganese-enhanced MRI thus allows assessment of the functional state of specific neuronal populations in the song system of living canaries in a manner reminiscent of functional MRI (but with higher resolution) or of 2-deoxyglucose autoradiography (but in living subjects).     

Cells born in adult canary forebrain are local interneurons

Thymidine autoradiography and retrograde transport of horseradish peroxidase (HRP) were combined to determine the connectivity of neurons born in adult canary forebrain. Adult male and female canaries were pretreated with [3H]thymidine to label cells undergoing DNA synthesis prior to mitosis. Thirty or 60 days later, neurons in a forebrain nucleus, hyperstriatium ventralis, pars caudalis (HVc), were labeled by retrograde transport of HRP injected into the only two nuclei known to receive a projection from HVc: robustus archistriatalis (RA) and area X of lobus parolfactorius. The birds were then killed and brain sections were treated to visualize cells containing HRP; these sections were processed for autoradiography to detect [3H]thymidine-labeled cells in the same tissue. More than 9% of all neurons in HVc were thymidine labeled; but of the almost 20,000 HRP-labeled projection neurons examined, fewer than 20 (0.1%) were labeled by the thymidine treatment. Furthermore, the median cell body size for area X-projecting cells was significantly larger than that of thymidine-labeled cells, and the median size of thymidine-labeled cells was significantly larger than that of RA-projecting cells. The simplest interpretation of these results is that the new neurons incorporated into nucleus HVc in adult canary brain are local interneurons, intermediate in size between neurons projecting to RA and area X.     

Sex and season influence the proportion of thin spike cells in the canary HVc

In songbirds, anatomical attributes of song nuclei exhibit sexual and seasonal differences. To extend these data to physiological correlates, neurons ( n= 374) were recorded in the HVc of male and female canaries during and outside the breeding period. Surprisingly, a particular type of action potential waveforms was observed more frequently in breeding than in non-breeding birds and in males than in females. These neurons showed both a shorter action potential duration (< 0.4 ms) and a higher firing rate (2.5 1.4 spikes/s) than the other neurons. Such characteristics are usually associated with interneurons in the songbird HVc as well as in the mammalian neocortex. Thus, these results provide the first electrophysiological evidence for an alteration of the neuronal network of HVc across sexes and seasons.     

Morphological features and electrophysiological properties of serotonergic and non-serotonergic projection neurons in the dorsal raphe nucleus. An intracellular recording and labeling study in rat brain slices

The morphology and electrophysiological properties of serotonergic and non-serotonergic projection neurons in the dorsal raphe nucleus (DRN) of the rat were examined in frontal brain slices. Biocytin was injected intracellularly into the intracellularly recorded neurons. Then the morphology of the recorded neurons was observed after histochemical visualization of biocytin. The recorded neurons extending their main axons outside the DRN were considered as projection neurons. Subsequently, serotonergic nature of the neurons was examined by serotonin (5-HT) immunohistochemistry. The general form of the dendritic trees is radiant and poorly branching in both 5-HT- and non-5-HT neurons. However, the dendrites of the 5-HT neurons were spiny, whereas those of the non-5-HT neurons were aspiny. The main axons of both 5-HT- and non-5-HT neurons were observed to send richly branching axon collaterals to the DRN, ventrolateral part of the periaqueductal gray and the midbrain tegmentum. In response to weak, long depolarizing current pulses, the 5-HT neurons displayed a slow and regular firing activity. The non-5-HT neurons fired at higher frequencies even when stronger current was injected. Some other differences in electrophysiological properties were also observed between the 5-HT-immunoreactive spiny projection neurons and the 5-HT-immunonegative aspiny projection neurons.     

LGN-projecting Neurons of the Cat's Pretectum Express Glutamic Acid Decarboxylase mRNA

There have been conflicting reports on the chemical nature of the projection of the pretectal nuclei [nucleus of the optic tract and dorsal terminal nucleus of the accessory optic tract (NOT DTN complex) and posterior pretectal nucleus] to the lateral geniculate nucleus and inferior olive. There is evidence that the pretecto-geniculate pathway is inhibitory. However, most attempts to verify the GABAergic nature of the projection neurons have failed. In order to answer this question, we employed a combination of retrograde transport and in situ hybridization. Rhodamine-labelled latex microspheres were injected into the electrophysiologically identified lateral geniculate nucleus. In addition, fluorescein-labelled latex microspheres were injected into the inferior olive. Retrograde axonal transport labelled large pretectal neurons. We then applied riboprobes specific for glutamic acid decarboxylase mRNA. We were able to demonstrate glutamic acid decarboxylase mRNA expression in up to 70% of lateral geniculate nucleus-projecting NOT-DTN and posterior pretectal nucleus neurons but in none of the pretecto-olivary projection neurons. The results suggest that the pretecto-geniculate projection is GABAergic in nature, which would confirm previous electrophysiological and morphological observations. The pretecto-olivary projection is not GABAergic.     

Metabolic and neural activity in the song system nucleus robustus archistriatalis: effect of age and gender

The sexually dimorphic robust archistriatal nucleus (RA) represents the telencephalic output of the bird song system. Here, we document sex-dependent changes in both the metabolic and neuronal activity of RA during the sensory and sensorimotor phases of song learning. From posthatching day (PHD) 20-63 in males but not females, RA and its input nucleus HVc showed sharp increases in cytochrome oxidase (CO) activity relative to surrounding archistriatum and the underlying shelf, respectively. In urethane-anesthetized birds, during the same period, the spontaneous activity of male RA neurons underwent dramatic changes in firing rate, distribution of interspike intervals, and bursting frequency, compared with other archistriatal cells. At PHD 20-21, RA neurons had extremely slow, irregular firing rates in birds of both sexes. In males, from PHD 30-36, RA neurons increased their firing rates and spiking activity became more regular, and at approximately PHD 38, strong bursts followed by inhibition (which in awake animals is associated with singing) began to be observed. Dual recordings from RA and HVc revealed synchronous bursting, with RA spikes lagging approximately 10 msec behind HVc. We conclude that changes in relative CO activity correlate with changes in spontaneous firing rates within RA and that patterns of RA spontaneous activity exhibit gradual change as birds enter early song and then again for plastic song. The emergence of strong burst patterns in RA occurs later in life than does input from HVc as established by tracer studies or based on observed HVc bursting in young animals.