刺激大鼠下丘脑背内侧核对丘脑束旁核痛相关神经元放电的影响

本文在 79只清醒麻痹大鼠身上,用玻璃微电极记录丘脑束旁核痛兴奋(PfPE)和痛抑制(PfPI)单位的放电及其对刺激下丘脑背内侧核(DMH)的反应,并观察切割脊髓背外侧束的效应。主要结果如下:(1)刺激DMH使PfPE 单位的自发放电及痛放电有明显的抑制作用,而使PfPI 单位的自发放电增多,并解除伤害性刺激引起的抑制效应;(2)刺激DMH引起PfPE 单位的抑制效应,在切割脊髓背外侧束后仍然出现。上述结果提示:DMH 对丘脑束旁核在处理痛觉信息上具有调制作用,这种调制作用可能不通过脑干下行性抑制系统完成,而主要是通过脊髓上联系抑制丘脑束旁核神经元对痛传入的反应。     

躯体和内脏传入冲动在大鼠束旁核内的会聚

在麻痹的大鼠上,分别刺激迷走神经、内脏大神经、坐骨神经、腓肠神经、睾丸和副睾,在对侧丘脑束旁核记录到了45个细胞的单位放电。根据诱发反应的潜伏期、时程和放电频谱分布的不同,可将他们分为五种类型,并且认为这些类型和刺激引起的感觉性质有关。在观察到的45单位中,29个的反应具有痛放电的特性,而且对躯体及内脏的传入冲动呈聚合性反应。其中2个单位只对内脏传入冲动产生反应。这项研究的结果表明,束旁核不仅是接受内脏传入的丘脑结构,而且也是一个整合内脏与躯体传入信息的中枢。     

家鸽臂丛和坐骨神经传入冲动在纹状体的投射

在53只家鸽的纹状体上系统地探查了刺激臂丛和坐骨神经所引起的平均诱发电位。结果发现,臂丛传入的投射区位于新纹状体、上纹状体和外纹状体之内,坐骨神经传入投射区则分别与臂丛传入的新纹状体投射区和上纹状体部分投射区重合;臂丛和坐骨神经投射区均接受身体两侧的传入。作者认为,家鸽纹状体内的前、后肢躯体感觉传入投射区是分散的,并非形成一个集中的中枢;前肢的投射区较大,可能与机能分化有关,身体不同部位的传入冲动在同一投射区内的会聚,对于肢体活动的整合具有重要意义。     

束旁核、中央中核对皮层体感觉区伤害性反应单位的影响

实验在清醒麻痹的猫上进行。先用记录诱发电位的方法,证明大脑皮层第 I 体感觉区(SI区)同一部位可接受来自外周神经、丘脑束旁核(Pf)和中央中核(CM)的上传信号;然后在这一皮层部位寻找在强电流刺激腓总神经时出现伤害性反应的神经元。在所观察的24个单位中,有20个单位如果先给予 Pf 刺激,可看到上述伤害性反应明显增强,增强的百分率平均在90.0%以上;在这同一组皮层单位,如果预先刺激 CM,有21个单位的伤害性反应明显减弱,反应抑制都在-55.6%以上。Pf 刺激本身对所观察单位的自发放电影响不明显,但 CM 刺激可明显抑制它们的自发放电。     

刺激家兔尾核对丘脑束旁核痛兴奋和痛抑制单位放电的影响

在51只清醒麻痹家兔身上,记录了丘脑束旁核痛兴奋(PfPE)和痛抑制(PfPI)单位的放电。观察刺激尾核头背部(DHCN)对 PfPE 和 PfPI 单位自发放电和痛放电的影响。(1)刺激 DHCN时,在28个 PfPE 单位中,19个的自发放电发生抑制反应,7个无变化,2个增强;在6个PfPI 单位中,5个的自发放电增加,1个无变化。(2)刺激 DHCN 时,在38个 PfPE 单位中。2个的痛放电兴奋增强,6个无变化,30个被抑制。其中12个呈抑制反应的单位,8个立即发生在刺激 DHCN 之后,并延续700—1600ms,在10个 PfPI 单位中,7个的痛放电发生兴奋反应,3个无变化。这些结果提示,DHCN 对丘脑 PfPE 和 PfPI 单位在处理痛觉信息上具有调制作用。根据抑制的潜伏期短和延续时间长的特点,推测这种调制作用可能既通过直接通路又有间接环路参与。     

刺激分离的脊髓背半部外周段对束旁核神经元伤害性反应的影响

用玻璃微电极记录了家兔束旁核细胞对强电刺激腓总神经的反应。在束旁核区域内可找到两类单位:一类是对腓总神经刺激产生长时间高频放电的痛敏单位,一类是对同样刺激发生自发放电长时间抑制的痛抑制单位。如预先以弱电流刺激已在 T_(12)或 L_1水平切断的背侧1/2脊髓的外周段,可使上述痛敏神经元的放电明显抑制,抑制率平均达87%;同样的脊髓刺激则可使痛抑制单位由于外周传入而出现的抑制性反应明显减弱。在静脉注射纳洛酮后,6个痛敏单位中有4个在刺激脊髓后不再出现原来的痛敏放电的抑制,2个单位仍能出现脊髓刺激的抑制效应。实验说明,到达束旁核水平的痛传入信号在通过脊髓时受到下行性抑制通路的影响,并且这种影响在多数情况下可能是通过内源性鸦片系统的参与而实现的。     

刺激中缝背核区对猫小脑皮层浦肯野细胞电活动的影响

本文研究了刺激外周神经及中缝背核区对猫小脑皮层浦肯野细胞(Purkinje Cell,PC)电活动的影响。在清醒的去大脑猫上记录刺激桡深神经(NRP)及腓深神经(NPP)时PC的电变化,并观察刺激中缝背核区对PC自发放电以及肢体神经传入冲动诱发活动的影响。结果表明,刺激NPP和NRP均可引起小脑皮层第Ⅴ和第ⅦA小叶的PC产生兴奋或抑制反应。刺激中缝背核区对PC自发放电以及诱发活动主要起抑制性影响。     

电刺激猫中脑导水管周围灰质和中缝大核对脊髓背角神经元伤害性感受反应的抑制

1.在氯醛糖麻醉的猫上,观察了电刺激中脑导水管周围灰质(PAG)和中缝大核(NRM)对脊髓腰段背角神经元传入活动的影响。2.按照对刺激的反应型式,在背角记录到非伤害性低阈值传入、广动力范围、伤害性热敏以及高阈值传入诱发的自发放电抑制等四类神经元。3.刺激 PAG和 NRM对记录到的多数背角神经元皮肤传入反应有明显抑制效应,而对自发放电抑制性神经元产生去抑制。4.比较刺激两脑区的抑制效应:NRM 作用较PAG 强;PAG 活动对背角伤害性反应抑制的选择性较 NRM强;阿片肽拮抗剂-纳洛酮拮抗NRM刺激的抑制。5.这些结果提示PAG和NRM对脊髓的下行抑制,可能有一部分是通过不同神经机制实现的。     

刺激兔丘脑不同核团和胼胝体引起的膈神经放电效应

实验在33例清醒、肌肉麻痹和切断双侧迷走神经的家兔上进行,观察了刺激丘脑不同核团(VIL,VL,VPM 和 MI)和胼胝体纤维以激活皮层时膈神经的放电效应。当在吸气相(膈神经放电时)给予上述核团及胼胝体纤维电脉冲刺激,可使膈神经放电短暂抑制,随后的呼气相缩短、吸气相提前出现。如果在呼气相刺激上述核团,也能使该呼气时相缩短,随后的吸气时相提前出现。当在皮层接受 VL 投射的局部区域给予回苏灵后,再刺激 VL,皮层诱发电位增大,除使原先的膈神经放电效应更为明显外,还可在呼气相刺激时引起膈神经即刻的短暂放电。以上实验结果提示,当用回苏灵使皮层活动加强后,刺激丘脑 VL 引起的膈神经放电效应明显增强。损毁红核或切断皮层下行传导束但保留皮层脊髓束后,刺激丘脑引起的膈神经放电效应均不受影响,表明传入冲动激活皮层后引起的膈神经放电效应可能主要经皮层脊髓束下传,而皮层红核脊髓束不起重要作用。     

鸣禽栗 新纹状体L复合区与发声控制系统的神经联系

利用辣根过氧化物酶顺、逆行追踪的方法对鸣禽栗端脑新纹状体Ｌ复合区的神经联系进行了研究。结果表明,新纹状体Ｌ复合区中的Ｌ２区主要接受来自丘脑卵圆核的传入,并与Ｌ１和Ｌ３区有纤维联系;而Ｌ１和Ｌ３区传出纤维投射至高级发声中枢腹侧的架区、古纹状体粗核喙背侧的杯区以及上纹状体腹部尾外侧等处;Ｌ复合区亦接受来自新纹状体前部巨细胞核内侧部的传入投射。     

刺激PAG对C纤维传入诱发皮层电反应的影响

电刺激中脑导水管周围灰质(Periaqueductal Gray,PAG)对 C 类纤维传入引起的体感皮层诱发电位(C-CEP)和脊髓背表面电位(C-SSP)均有明显的抑制作用,对前者的作用更大。在脊髓背表面滴加赛庚啶后,刺激 PAG 对 C-SSP 的抑制变得不明显,表明 PAG下行抑制通路被阻断;但刺激 PAG 对 C-CEP 抑制仍明显,仅稍减小。提示 PAG 除了通过下行通路以外,可能还通过上行通路抑制 C-CEP。在脊髓背表面滴加赛庚啶后,静脉注射纳洛酮和赛庚啶可明显减弱电刺激 PAG 对 C-CEP 的抑制作用,提示内源性阿片样物质和5-羟色胺可能是上行抑制通路中主要的神经递质。     

刺激大鼠尾核对丘脑束旁核躯体-内脏会聚神经元放电的影响

实验记录大鼠丘脑束旁核躯体-内脏会聚(PfSV)神经元伤害性放电。观察刺激尾核(Cd)对 PfSV 神经元放电的影响。(1)Cd 对刺激内脏大神经诱发 PfSV 神经元伤害性放电有抑制作用(n=19)。(2)Cd 对刺激腓浅神经和内脏大神经诱发同一 PfSV 神经元伤害性放电均有抑制作用(n=11)。结果提示,躯体和内脏痛觉信息可会聚到丘脑束旁核同一神经元,Cd 可能不仅能抑制躯体痛也能抑制内脏痛。     

The sensory trigeminal system in birds: input, organization and effects of peripheral damage. A review.

The primary sensory trigeminal system in birds comprises the mesencephalic trigeminal nucleus and the trigeminal ganglion with projections to the principal sensory nucleus (PrV) and the descending tract with its subnuclei. Other cranial nerves can contribute to PrV and the descending system that together form the somatosensory system of the head. There is also a proprioceptive component. The somatosensory system comprises a component serving tactile sense and a nociceptive component. The former processes information from many mechanoreceptors in beak and tongue; both PrV and subnuclei of the descending system are involved. The nociceptive component consists of small ganglion cells projecting presumably to layers I and II of the caudal subnucleus of the descending trigeminal system and cervical dorsal horn; this is the only trigeminal region showing immunoreactivity for substance P. The effects of amputation of the tips of the beak of chickens (debeaking) are estimated by fiber counts in electron microscopic preparations of the trigeminal branches innervating that area, and by cell counts in Nissl stained sections of the trigeminal ganglion. Our data indicate that debeaking causes a loss of exteroceptive units, but not of nociceptive units. Comparison of sections stained for the presence of substance P (immunohistochemistry) did not reveal a long-term effect on the nociceptive system suggestive of the occurrence of chronic pain.     

γ—氨基丁酸在联合皮层抑制C类纤维皮层诱发电位效应中的作用

电刺激猫大脑皮层前外侧回联合区(ALA)对隐神经C类纤维传入引起的体感皮层(SI)诱发电位(C-CEP)有明显的抑制作用;侧脑室注射γ-氨基丁酸(GABA)能使C-CEP的幅值显著变小,潜伏期延长,表明GABA对C-CEP也有抑制作用;侧脑室注射GABA受体拮抗剂荷包牡丹硷后,电刺激ALA对C-CEP的抑制作用明显减弱,提示内源性GABA的释放可能参与大脑皮层联合区对C-CEP的调制过程。     

刺激大脑皮层联合区对C类纤维传入诱发皮层电反应的影响

电刺激猫大脑皮层前外侧回联合区(ALA)能使隐神经 C 类纤维传入引起的体感皮层(S(?)区)诱发电位(C-CEP)的幅值明显变小,并有后作用,表明 ALA 对 C-CEP 有抑制作用;切断ALA 与 SI 区之间的皮层内纤维联系后,ALA 对 C-CEP 的抑制作用明显减弱,抑制时程缩短;侧脑室微量注射阿片受体拮抗剂纳洛酮后,电刺激 ALA 对 C-CEP 的抑制作用明显减弱,表明 ALA 对 C-CEP 的抑制作用的作用途径之—可能是通过 ALA 与 SI 区之间的皮层内神经径路;可能与内源性阿片样物质的释放有关。提示大脑皮层联合区可能对体感皮层 C-CEP 有调制作用。     

Long systems of the dorsolateral fascicle: influence of afferentation from the splanchnic region.

The influence of afferentation from the splanchnic region on the activity of long systems in the dorsolateral fascicle (DLF) was studied in chloralose-anaesthetized cats. Ascending axons (the dorsal spinocerebellar tract, DSCT and the spinocervical tract, SCT) did not respond to splanchnic stimuli. Conditioning from the splanchnic region modified their activity; the effect (mainly inhibitory) was strongest in the case of exteroceptive channels. The reaction of long propriospinal neurones depended on whether they belonged to ascending or descending pathways. No responses to splanchic stimuli were observed in the axons of ascending (proprioceptive, exteroceptive) units and conditioning from the splanchnic region only modified their activity. In decending axons, synaptic discharges with a long latent period (over 20 msec) were generated. The interaction of inputs from the visceral and somatosensory regions resulted in reciprocal inhibition of the tested activity. In axons descending from suprasegmental areas, splanchnic afferentation generated synaptic discharges with a time course comparable to spino-bulbo-spinal activity. Interaction with the responses from somatic nerves resulted inhibition of the tested activity. The results confirmed that the splanchnic region participates in modifying and evoking activity in the long DLF systems.     

刺激大脑皮层体感Ⅰ区和大脑脚对大鼠脊髓背角神经元伤害感受性反应的影响

在大鼠用玻璃微电极细胞外记录的方法,观察了刺激皮层体感Ⅰ区(SI区)和大脑脚(CP)对皮肤强电刺激诱发的脊髓背角广动力范围(WDR)神经元长潜伏期反应(C-反应)的影响。结果表明刺激SI区对背角WDR神经元C-反应的影响以抑制为主,刺激CP的作用与刺激SI区的作用相似,但刺激CP更为有效。抑制作用的持续时间在不同神经元差别很大,短者在刺激停止后仅持续400ms,长者可达10min以上。静注纳洛酮对抑制作用无明显影响,静注二甲麦角新碱在部分神经元可使抑制作用明显减弱或完全消失,提示5-HT部分参与皮层下行抑制作用的实现,而内鸦片肽则否。     

Connections between wide-field monocular and binocular movement detectors in the brain of a hawk moth

Summary Recordings were made in the brain of Sphinx ligustri of pairs of directionally selective movement detectors, and the spike trains analysed with a computer for possible synaptic connections between two classes of movement detector. (1) Neurones with large binocular fields which arise in the medial protocerebrum and project to the medulla or lobula of one optic lobe, or to the ventral nerve cord. (2) Movement detectors which project from the lobula complex of one optic lobe to the opposite medial protocerebrum. The majority of the second group had back-to-front preferred directions over the ipsilateral eye, and of these many were weakly sensitive to stimuli to the opposite eye. The ipsilateral receptive field covered most of the eye.Optic lobe output cells with the appropriate preferred direction provide a powerful excitatory input to the binocular movement detectors centrifugal to the medulla. Each centrifugal movement detector probably receives excitatory inputs from no more than two optic lobe output cells with back-to-front preferred direction. The same set of optic lobe output neurones probably feeds several cells projecting to the medulla and lobula of both optic lobes, and, possibly, to the ventral nerve cord.Evidence was obtained that the optic lobe output cells themselves receive few excitatory inputs, and that therefore the receptive fields of their input cells are large.Two moving stimuli were presented in different areas of the receptive field. Movement through the null direction in one area inhibited the response to movement in the preferred direction in another area. This suppression was stronger in optic lobe output cells with front-to-back preferred direction than in units with back-to-front preferred direction. Thus the optic lobe output cells, or wide-field units feeding them, receive inhibitory inputs from wide-field units with the opposite preferred direction.Similar tests in which moving stimuli were presented to both eyes gave results indicating that the binocular centrifugal movement detectors may receive inhibitory inputs from movement detectors with back-to-front preferred direction. The possible functional significance of these inhibitory inputs is discussed.I am very greatful to F. A. Miles for helpful discussion and criticism. Financial support came from the U. K. Science Research Council.     

大鼠中脑、内脏和躯体传入在旁巨细胞外侧核神经元的聚合

用细胞外记录的方法观察大鼠巨细胞旁外侧核（ＰＧＬ）对刺激中脑导水管周围背侧部（ｄＰＡＧ）及腹外侧部（ｖＰＡＧ）、腓深神经（ＤＰＮ）、正中神经（ＭＮ）和内脏大神经（ＧＳＰＬ）的反应。这些神经元不仅对某一处刺激部位起反应,而且倾向于对其它任一刺激部位也起反应。８９％（７３／８２）的神经元接受两处或两处以上来源的汇聚投射。６０％（２１／３５）的神经元由于具有压力敏感性,并且其下行投射到脊髓的轴突具有慢的     

Distribution of inhibitory synapses on the somata of pyramidal neurons in cat motor cortex

The mechanisms by which cortical neurons perform spatial and temporal integration of synaptic inputs are dependent, in large part, on the numbers, types, and distributions of their synapses. To further our understanding of these integrative mechanisms, we examined the distribution of synapses on identified classes of cortical neurons. Pyramidal cells in the cat motor cortex projecting either to the ipsilateral somatosensory cortex or to the spinal cord were labeled by the retrograde transport of horseradish peroxidase. Entire soma of selected corticocortical and corticospinal cells were examined using serial-section electron microscopy. The profiles of these somata and the synapses formed with each of these profiles were reconstructed from each thin section with a computer-aided morphometry system. All somatic synapses were of the symmetrical, presumably inhibitory type. For both cell types, these synapses were not homogeneously distributed over the somatic membrane, but were clustered at several discrete zones. The number and density of synapses on the somata of different corticocortical and corticospinal neurons were not significantly different. However, the density of these synapses was inversely correlated with the size of their postsynaptic somata. We discuss the significance of these findings to the integrative properties of cortical neurons.