刺激隐神经中C类纤维诱发的小脑浦肯野细胞简单锋电位反应

用玻璃微电极记录了猫小脑浦肯野细胞的简单锋电位(PC-SS)。在标准化互协方差函数图中,PC-SS自发放电无明显波峰;弱刺激隐神经只引起A类纤维传入时,PC-SS出现A类诱发放电反应(A-CED),它包括潜伏期为16.7±0.9ms的早反应和270.8±12.8ms的晚反应。用极化电流选择性阻滞A类纤维传导后,强刺激只引起C类纤维单独传入时,出现潜伏期为142.4±4.3ms的C类诱发反应(C-CED)。强刺激同时引起A类和C类纤维传入时,只出现A-CED而不出现C-CED。按标准化功率谱密度函数分析,PC-SS自发放电可分为两种类型。一类为高峰型,最大能量峰值平均为15.7±4.7×10~(-3),峰频为4.07±1.67Hz;刺激A类纤维使峰值增大,而刺激C类纤维却使峰值减小。另一类为低峰型,峰值为8.4±1.4×10~(-3),峰频为3.67±2.90Hz。刺激A类和C类纤维均使峰值增大,前者增大更多,但峰频均无显著性变化。上述结果表明,C类纤维传入可以到达小脑浦肯野细胞,引起特异的PC-SS放电反应。     

大鼠前庭内侧核在前庭—交感反应中的作用

实验在氯醛糖和尿酯混合麻醉的大鼠上进行。在内脏大神经上记录刺激同侧前庭神经进入脑干处的交感反应。电刺激前庭神经可在同侧内脏大神经引出—明确的叠加反应,其平均潜伏期为45.8±6.98ms,时程为55.21±5.35ms。增加刺激强度,反应幅度也增加,但潜伏期不变。用前庭内侧核(NVM)的片层场电位作为指标并选择其相位倒转处作刺激点,可在同侧内脏大神经记录到潜伏期为32ms 的叠加反应,而同一动物刺激前庭神经入脑处时内脏大神经反应的潜伏期为43ms。在 NVM 头端损毁后,此前庭-交感反应明显减小,再损毁尾端 NVM 后,此反应消失。损毁 Deiters 核对前庭-交感反应无影响。这些结果表明 NVM在内脏大神经记录到的前庭-交感反应中是一重要的中继站。     

足月新生儿听觉脑干电反应的特性

本文工作根据北京市儿童医院临床的需要,在临床实验条件下对足月新生儿的ABR进行了测量,以期分析足月新生儿ABR的电反应特征。 新生儿听觉脑干反应(ABR)的波形是Ⅰ、Ⅲ、Ⅴ波为主的连续波复合体;新生儿在声强80dB(HL)刺激频率20次/秒的短声刺激条件下,I、Ⅲ、Ⅴ波潜伏期大体为2.50,5.00和7.00ms;新生儿ABR潜伏期—刺激强度函数的斜率是30—60μsec/dB(声刺激强度从80到50dB(HL),声刺激频率20次/秒);新生儿ABR Ⅴ波对Ⅰ波的比率大于1.0(短声强度80dB(HL),刺激频率20次/秒);在80dB(HL)短声条件下,改变声刺激频率(从20次/秒增止100次/秒),Ⅴ波潜伏期约延长0.6—1.0ms;新生儿ABR阈值在30—60dB(HL)的范围。综上所述新生儿ABR电反应特性,可以为其听力和脑干功能的临床诊断提供可靠的指标和依据。     

重复短声调频在豚鼠诱发的皮层慢反应及反应阈

重复短声调频在豚鼠诱发的皮层慢反应的基本特征与其他声刺激诱发者相似,它为一正负正三相波,第一正峰的潜伏期约50ms。以调频深度表示的反应阈△f_r较易测定,可以作为动物频率辨别能力的定量表达。对从250至4000pps的复频,豚鼠△fr的均值只在2.0至2.6pps间波动,因此对需要比较不同状况时△fr的变化,一般只取复频1000pps的△f_r便可代表,不必取整个△f_r曲线。听觉系统对重复短声的频率变化比纯音的容易检别,本文对可能的机理进行了讨论。     

隐神经及光刺激对猫视前区-下丘脑前部单位放电的影响

猫先用氨基甲酸乙酯-氯醛糖麻醉,然后用三碘季铵酚剂制动并人工呼吸,从脑的腹侧面接近视前区-下丘脑前区(PO-AH)。用玻璃微电极记录PO-AH的单位活动及其对不同强度的隐神经和闪光刺激的反应。用数据处理机作刺激前后的密度序列直方图。共观察了200个PO-AH单位,大多数单位的自发放电频率为1-15次/秒。观察了隐神经刺激对140个单位的效应。其中对隐神经刺激反应的有69个(49.3％),包括兴奋的23个,抑制的36个,反兴奋,致的10个。在69个被躯体神经激活的单位中,有4个仅可被C纤维阈以上的刺激所应不一有6个仅可被C纤维阈以上的刺激所抑制,前者相当于“痛敏”单位。观察了光刺激对181个单位的效应,其中有反应的有93个(51.4％),包括兴奋反应的21个,抑制反应的62个,反应不一致的10个.对双侧光刺激均有反应的10个。对光刺激的反应多数是短潜伏期的,只有一个是长潜伏期的。有34个单位既对光刺激、又对躯体神经刺激反应,属于会聚单位。在重复刺激作用下,PO-AH单位常表现出反应减弱倾向,对于伤害性以及视觉信息向下丘脑输入的特点以及下丘脑神经元与网状结构神经元活动的相似性作了简要讨论。     

蛙离体视网膜中杆系统对锥系统的抑制作用

在蛙离体视网膜标本上研究了由条件刺激(F_c)引起的快速暗适应(RDA)过程中b 波的变化。当F_c超过一定强度时,以501nm 闪光为测试刺激(F_(t(501)))时b波阈值单调下降,先为锥相后为杆相,两者过渡处呈现杆-锥转折;但以654nm闪光为测试刺激时(F_(t(654))),阈值先略有下降,继而上升,之后再下降。F_(t(654))应阈值在RDA 过程中的这种升高是反映575锤系统的活动受到502杆系统抑制的结果,433杆系统对此没有明显的贡献,主要依据是:(1)F_(t(654))反应阈值的上升在时间上与暗适应曲线的杆相的出现一致;(2)在RDA 过程的锥相,反应的光谱敏感性与锥色素吸收光谱一致,而在F_(t(654))反应阈值上升到最大值时,反应的光谱敏感性与502杆色素的吸收光谱非常接近;(3)对502杆系统作用等效的F_(c(439))、F_(c(501))和F_(c(616))作用后,F_(t(654))的敏感度变化在整个RDA 过程中基本相同。     

刺激中缝背核压抑大鼠小脑浦肯野细胞对苔状和爬行纤维传入的反应

本文在麻醉并制动的大鼠上观察了中缝背核(DR)条件刺激对由苔状和爬行纤维传入引起的小脑浦肯野细胞(PC)诱发反应的影响。主要结果有:(1)刺激大脑皮层感觉运动区可以引起苔状和爬行纤维向对侧小脑皮层第Ⅵ和Ⅶ小叶的传入,因而在该小叶上记录到 PC 的诱发简单锋电位(SS)和复杂锋电位(CS)反应,潜伏期分别是8—25和12—30ms。(2)以不影响PC 自发 SS 和 CS 活动的阈下强度刺激 DR,可显著地压抑 PC 对于刺激感觉运动皮层引起的苔状和爬行纤维兴奋所产生的诱发 SS 和 CS 反应,这种压抑作用可持续数百毫秒。(3)DR条件刺激对 PC 的诱发 SS 和 CS 反应的压抑作用可以被静脉注射5-HT 受体阻断剂羟甲丙基甲基麦角酰胺所减弱或阻断。上述结果表明 DR 的5-HT 能纤维传入可以降低苔状和爬行纤维对 PC 的突触作用效力,抑或降低 PC 对突触传入的反应敏感性,提示中缝-小脑5-HT,能纤维传入系统参与了小脑某些重要的神经活动过程。     

GABA拮抗剂荷包牡丹碱对猫外膝体神经元方位调谐特性的影响

在十二只成年猫上用多管玻璃微电极记录了外膝体神经元对不同空间频率和不同方位的移动正弦光栅刺激的反应,共详细测定并对比研究了３８个方位敏感性细胞在微电泳荷包牡丹碱前后的方位调谐特性。在最优空间频率附近的较低空间频率下,微电泳荷包牡丹碱后,外膝体细胞的方位敏感性强度（Ｂｉａｓ）降低,而在截止频率附近的较高空间频率下,微电泳前后外膝细胞的方位敏感性强度（Ｂｉａｓ）从总体上看没有显著变化。结果表明,以空间频率为截止频率附近的移动正弦光栅作为刺激,外膝体细胞的方位敏感性可能主要是由视网膜神经节细胞的兴奋输入所形成,而非外膝体内抑制机制所致。     

大鼠中脑导水管周围灰质和束旁核联系途径的电生理分析

在48只清醒大鼠的中脑导水管周围灰质(PAG)记录到228个有自发放电的单位,检查了它们对束旁核(Pf)刺激和外周伤害性刺激和触刺激的反应,其中有76个单位对 pf 刺激有反应,反应型式有如下三类。8个单位在 Pf 刺激时出现逆行反应,潜伏期为3.18±0.57(SD)ms,传导速度相当于1.41m/s;这些单位的自发放电频率为1.1±0.45Hz,且不受夹尾或触尾刺激的影响。44个单位在 pf 刺激时出现顺行抑制;它们的自发放电频率为12.1±3.7(SD)Hz,且大多数单位(61.3%)在夹尾刺激时出现明显的增频反应,此反应亦可被 pf 刺激所抑制。24个单位在 pf 刺激时出现顺行兴奋;它们的自发放电频率为5.8±14(SD)Hz,对夹尾刺激表现增频或减频反应的单位数大致相等。对这些不同性质的 PAG 单位在中枢痛传递和痛感受的调制中所起的作用进行了讨论。     

鲤属鱼L-型外水平细胞所接收的锥细胞信号

在保持正常血液循环的眼杯标本上,用细胞内微电极技术记录了 L-型外水平细胞(LHC)的反应,并且用颜色光适应方法分析了它所接收的锥细胞输入。结果表明,在白光明适应条件下,LHC 依然接收红敏和绿敏锥细胞的输入,但两者的相对贡献与暗视时有所不同。用蓝适应光可以基本上分离红敏锥细胞的信号;而在红色背景光下,绿敏锥细胞主导了反应的上升相和撤光后回跳相(off-rebound),但在反应平台处却是红敏锥细胞的信号作出主要贡献,表明不同的锥细胞信号显然有不同的潜伏期和时程。     

Simultaneous Recording of Input and Output of Lateral Geniculate Neurones

TO understand the way in which the cat dorsal lateral geniculate nucleus (LGN) processes visual information it would be useful to know the number and type of retinal inputs to individual LGN neurones. Using electrical stimulation of the optic nerve Bishop et al.¹concluded that an impulse in a single optic nerve fibre is sufficient to excite a single LGN neurone. From the appearance of excitatory postsynaptic potentials (EPSPs) recorded essentially intracellularly, Creutzfeldt suggested that LGN neurones are driven by perhaps one² or a few³ retinal ganglion cells. Hubel and Wiesel⁴ proposed models of convergence of several retinal inputs on single LGN neurones based on analyses of receptive fields. Guillery⁵ produced anatomical evidence that some types of LGN neurones receive inputs from several different retinal fibres. Now we report direct observations which were made by recording simultaneously from single LGN neurones and from individual retinal ganglion cells which provided excitatory input to them. We shall not consider inhibitory influences, which are currently under study.     

Changes in signal transmission by neurons of the cat lateral geniculate nucleus by acute deafferentation and early degeneration.

1. The responses of single principal cells of the cat lateral geniculate nucleus (LGN) were recorded extracellulary from the optic radiation (OR) axons or intracellularly from the LGN. Electrical stimuli at different frequencies were applied to the optic tract (OT) to test the transneuronal and the synaptic signal transmission in the LGN. 2. The effect of acute deafferentation (by photocoagulation of the retinal receptive field) or of synaptic degeneration induced 2-4 days prior to the recording time on the LGN neuron signal transfer was studied. Immediately after deafferentation, the synaptic signal transfer by LGN neurons exhibits signs of hyperexcitability leading to multiple neuronal discharges. This acute deafferentation hyperexicitability is probably caused mainly by the disapperance of lateral inhibition mediated by LGN interneurons. The deafferentation hyperexcitability disappeared during electrical stimulation of the OT at frequencies greater than 10/sec. 3. With progressing degeneration of the synaptic terminals during the 2nd to 4th day after interruption of the optic nerve axoplasmic flow, the synaptic signal transfer by LGN neurons gradually deteriorates and ceases at the end of the fourth day. The signs of this deterioration (larger temporal scatter, increased exhaustability and reduced upper frequency limit of the transneuronal signal transmission and gradual reduction of the EPSP amplitude in D-neurons) were quantitatively investigated. 4. The neurophysiological data obtained at different levels of synaptic terminal degeneration are well correlated with morphological changes found within the degenerating synaptic terminals.     

Electrophysiological maturation of neurons of the lateral geniculate nucleus after lesion of ponto-geniculo-occipital pathways in kittens

Bilateral mesencephalic lesions, which suppress the PGO activity in the lateral geniculate nucleus (LGN), were performed at two weeks of age in the kitten, and the effects on the electrophysiological development of this nucleus were analyzed at 6 weeks of age. The latencies of LGN cells after electrical stimulation of the optic chiasma were larger, and the number of the differentiated X cells was smaller than those of age paired controls. However, the response of the ganglion fibers was not modified. These results, compared to those obtained on 30 days old kittens, and on animals with a unilateral lesion, suggest that the suppression of PGO inputs to the LGN induced a delay in the electrophysiological maturation of this nucleus.     

Responses to features of the calling song by ascending auditory interneurones in the cricket Gryllus campestris

ABSTRACT. In female Gryllus campestris L., three functional types of ascending auditory intemeurones have been studied by recording from them extracellularly in the split cervical connectives using suction electrodes. Type 1 neurones are characterized by an optimal sensitivity to the carrier frequency of the species calling song (4–5 kHz). They copy the syllable and pause structure of the call at all intensities. The patterned spike discharge is observable at least 8 dB above absolute threshold. With suprathreshold stimulation, the neurones exhibit maximal responses (number of spikes/chirp) around the carrier frequency. The intensity response curves are approximately linear in the range of 40–90 dB SPL. The envelope of each syllable is reflected by a corresponding change in the firing rate, and syllable periods of 24ms and longer are resolved. This type can be considered as a neural correlate for phonotactic behaviour of the female where the syllable period has been found to be the most important temporal parameter. Type 2 neurones are most sensitive in the range of 4–6 and 11–13 kHz. They copy the syllable and pause structure of the species calling song at low and moderate intensities. However, the spikes invade the intersyllable pauses, when stimulated with the calling song at higher intensities (above 85 dB). This is particularly apparent at the onset of a chirp series. The slope of the intensity—response curve mimics that of type 1 units. The neurones cannot follow syllable periods shorter than 32 ms. Type 3 neurones differ from types 1 and 2 by a rather broad-band sensitivity in the range of 3–16 kHz, and in copying the chirp as a whole. Even at low stimulus intensities, the intersyllable pauses are filled with spikes, and information about the syllable—pause structure is lost. Stimulation with suprathreshold intensities gives rise to a rather uniform, broad-band response without distinctive peaks. The intensity—response curve is characterized by a higher absolute threshold, and by the reduction in the response magnitude starting above 70–80 dB. These units are not suitable for copying the calling song temporal structure in detail, but would indicate the chirping rhythm. Their strong response in the range of the species courtship song carrier frequency make them suitable to copy the courtship song.     

Element Distribution in Visual System,the Optic Chiasma,Lateral Geniculate Body,and Superior Colliculus

To elucidate compositional changes of the visual system with aging, the authors investigated age-related changes of elements in the optic chiasma, lateral geniculate body, and superior colliculus, relationships among their elements, relationships among their brain regions from a viewpoint of elements, and gender differences in their elements by direct chemical analysis. After ordinary dissection at Nara Medical University was finished, the optic chiasmas, lateral geniculate bodies, and superior colliculi were resected from identical cerebra of the subjects. The subjects consisted of 14 men and 10 women, ranging in age from 75 to 96 years (average age = 85.6 ± 5.9 years). After ashing with nitric acid and perchloric acid, element contents were determined by inductively coupled plasma-atomic emission spectrometry. As the result, the average content of P was significantly higher in the optic chiasma and superior colliculus compared with the lateral geniculate body. Regarding age-related changes of elements, no significant changes with aging were found in seven elements of the optic chiasma, lateral geniculate body, and superior colliculus in the subjects more than 75 years of age. The findings that with regard to the relationships among elements, there were extremely significant direct correlations between Ca and Zn contents and significant inverse correlations between Mg and Na contents were obtained in common in all of the optic chiasma, lateral geniculate body, and superior colliculus. It was examined whether there were significant correlations among the optic chiasma, lateral geniculate body, and superior colliculus in the seven elements and the following results were obtained: There were significant direct correlations between the optic chiasma and lateral geniculate body in both the P and Mg contents; there was a significant direct correlation between the optic chiasma and superior colliculus in the Fe content; and a significant direct correlation was found between the lateral geniculate body and superior colliculus in the Mg content. Regarding the gender differences in elements, it was found that both the Ca and Zn contents of the lateral geniculate body were significantly higher in women than in men.     

Coarse-to-fine changes of receptive fields in lateral geniculate nucleus have a transient and a sustained component that depend on distinct mechanisms

Visual processing in the brain seems to provide fast but coarse information before information about fine details. Such dynamics occur also in single neurons at several levels of the visual system. In the dorsal lateral geniculate nucleus (LGN), neurons have a receptive field (RF) with antagonistic center-surround organization, and temporal changes in center-surround organization are generally assumed to be due to a time-lag of the surround activity relative to center activity. Spatial resolution may be measured as the inverse of center size, and in LGN neurons RF-center width changes during static stimulation with durations in the range of normal fixation periods (250-500 ms) between saccadic eye-movements. The RF-center is initially large, but rapidly shrinks during the first ~100 ms to a rather sustained size. We studied such dynamics in anesthetized cats during presentation (250 ms) of static spots centered on the RF with main focus on the transition from the first transient and highly dynamic component to the second more sustained component. The results suggest that the two components depend on different neuronal mechanisms that operate in parallel and with partial temporal overlap rather than on a continuously changing center-surround balance. Results from mathematical modeling further supported this conclusion. We found that existing models for the spatiotemporal RF of LGN neurons failed to account for our experimental results. The modeling demonstrated that a new model, in which the response is given by a sum of an early transient component and a partially overlapping sustained component, adequately accounts for our experimental data.     

The ipsilateral optic tracts in the rat. - I) Area of retinal origin

An attempt was made to sever the optic chiasma in the mid-sagittal plane in 12 rats. This was successful in 8 animals. The area of retina giving rise to the uncrossed fibres was determined from the position of undegenerated retinal ganglion cells in each eye following section of the chiasma. The ganglion cells giving rise to the uncrossed optic fibres occupy about 40 degrees of the temporal retina, corresponding to the the binocular overlap in the visual field.     

Correlation between conduction velocities in optic nerve and optic radiation fibers in the cat

Responses of relay neurons of the dorsal lateral geniculate body to stimulation of area 17 of the visual cortex and the optic chiasma were studied in curarized cats. A high degree of correlation was found between the latent periods of antidromic responses of these neurons to stimulation of the visual cortex and orthodromic responses of the same neurons to stimulation of the optic chiasma (r=0.895; P=0.01). In 9% of cases antidromic unit responses were recorded to stimulation of the optic chiasma, evidence that the optic nerve contains centrifugal fibers. The functional role of the temporal dispersion of the afferent flow in the visual system is discussed.A. A. Bogomolets Institute of Physiology, Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Neirofiziologiya, Vol. 10, No. 6, pp. 606–612, November–December, 1978.     

Dynamical changes and temporal precision of synchronized spiking activity in monkey motor cortex during movement preparation.

Movement preparation is considered to be based on central processes which are responsible for improving motor performance. For instance, it has been shown that motor cortical neurones change their activity selectively in relation to prior information about movement parameters. However, it is not clear how groups of neurones dynamically organize their activity to cope with computational demands. The aim of the study was to compare the firing rate of multiple simultaneously recorded neurones with the interaction between them by describing not only the frequency of occurrence of epochs of significant synchronization, but also its modulation in time and its changes in temporal precision during an instructed delay. Multiple single-neurone activity was thus recorded in monkey motor cortex during the performance of two different delayed multi-directional pointing tasks. In order to detect conspicuous spike coincidences in simultaneously recorded spike trains by tolerating temporal jitter ranging from 0 to 20 ms and to calculate their statistical significance, a modified method of the 'Unitary Events' analysis was used. Two main results were obtained. First, simultaneously recorded neurones synchronize their spiking activity in a highly dynamic way. Synchronization becomes significant only during short periods (about 100 to 200 ms). Several such periods occurred during a behavioural trial more or less regularly. Second, in many pairs of neurones, the temporal precision of synchronous activity was highest at the end of the preparatory period. As a matter of fact, at the beginning of this period, after the presentation of the preparatory signal, neurones significantly synchronize their spiking activity, but with low temporal precision. As time advances, significant synchronization becomes more precise. Data indicate that not only the discharge rate is involved in preparatory processes, but also temporal aspects of neuronal activity as expressed in the precise synchronization of individual action potentials.     

Temporal organization of interneuronal relations in the cerebral cortex of the cat in relation to the level of alimentary motivation

By means of records of multicellular activity, interneuronal relations and their modifications in two cortical zones (Visual and motor) were studied in cats at different levels of alimentary motivation. For quantitative evaluation of interneuronal relations the statistic method of cross-correlation analysis of impulse trains was used in determining the probability of the appearance of the discharge of one neurone after the impulse of the other one. For groups of neurones in both investigated cortical areas, three-neurones microsystems were singled out and their activity was analyzed by temporal parameters of interaction between neurones at the interval of 120 ms, both within one microarea (intraanalyzer connections) and between microareas of two cortical zones. The correlation of temporal parameters of interneuronal connections (temporal delays in the activity of neuronal pairs) changed depending on spatial localization of neurones and functional condition of the animals. The existence is suggested of "informational" (1-30 ms) and "motivational" (90-120 ms) values of interneuronal relations for interanalyser connections.