Activation of the nuclei of Goll and Burdach in the medulla oblongata by visceral afferent systems

Projections of the mesenteric and pelvic nerves in the nuclei of Goll and Burdach were studied by the evoked potentials method in cats anesthetized with chloralose and immobilized with listhenon. Stimulation of visceral nerves is accompanied by the development of biphasic potentials with an initial positive wave. Potentials were recorded in all parts of the nuclei studied. The latent periods of responses to stimulation of the mesenteric nerves varied from 13 to 22 msec, and to stimulation of the pelvic nerves from 8 to 21 msec. Potentials appeared later in the nucleus of Burdach in response to stimulation of the same nerves. The amplitudes of the responses depended on the location of the recording electrode. The features of organization of projections of these visceral nerves suggest the existence of special nuclear formations for projections of visceral nerves in the medulla similar to the para-alar nucleus for the pelvic nerves.     

Use of antidromic evoked potentials in placement of dorsal cord disc electrodes

Intraoperative recordings of somatosensory evoked potentials were made in 16 patients undergoing implantation of a dorsal cord stimulation system. Antidromic recordings, obtained by stimulating through the dorsal cord electrode placed in the epidural space and recording over peripheral nerves in the painful region of the body, and much higher signal-to-noise ratios and could be obtained with greater reliability than standard orthodromic recordings. When the placement of the electrode was adjusted to obtain evoked responses in the painful region, paresthesias referred to that region were obtained in virtually every case. Use of this procedure allows implantation and internalization of the electrodes in a single procedure under general anesthesia, and reduces the necessity of subsequent revisions.     

Interactions of somatosensory evoked potentials: simultaneous stimulation of two nerves

To analyse the mechanism by which sensory inputs are integrated, interactions of somatosensory evoked potentials (SEPs) in response to simultaneous stimulation of two nerves were examined in 12 healthy subjects. Right, left and bilateral median nerves were stimulated in random order so that a precise comparison could be made among the SEPs. The arithmetical sum of the independent right and left median nerve SEPs was almost equal within 40 msec of stimulus onset to that evoked by the simultaneous stimulation of bilateral median nerves. However, a difference emerged after 40 msec. The greatest difference was recorded after 100 msec. Sensory information from right and left median nerves may interact in the late phase of sensory processing. Left median, left ulnar, and both nerves together were stimulated. The sum of the SEPs of left median and ulnar nerves was not equal to that evoked by the simultaneous stimulation of the two nerves even at early latencies. Differences between them were first recorded at 14–18 msec and became greater after 30–40 msec. It is suggested that the neural interactions between impulses in the median and ulnar nerves begin below the thalamic level.     

Evoked potentials of the medulla oblongata of the skate in response to stimulation of lateral line nerves

The characteristics of the bioelectrical reactions of structures of the medulla oblongata connected with lateral line electro- and mechanoreceptor were investigated in acute experiments on skates under urethane anesthesia. The parameters of the evoked potentials (EP) are characteristic of each of the lateral line nerves studied. A comparison of the characteristics of the fast and slow components of the EP obtained by stimulation of nerves of the medulla oblongata makes it possible to state a hypothesis concerning the presynaptic origin of the fast and the postsynaptic origin of the slow components of the EP. A dependence of the magnitude of the EP on the amplitude of the stimulus and on the location of the active electrode was found. The location of the focus of maximum activity was determined for each of the nerves investigated. A correlation was established between some parameters of the bioelectrical reactions of the medulla oblongata and the morphophysiological properties of the fibers which make up the nerves studied. The results obtained make it possible to assume the presence in the medulla oblongata of spatially arranged structures responsible for the development of the bioelectrical effects in response to stimulation of the lateral line nerves of fish.I. P. Pavlov Institute of Physiology, Academy of Sciences of the USSR, Leningrad. Translated from Neirofiziologiya, Vol. 3, No. 3, pp. 284–292, May–June, 1971.     

Somatosensory evoked potentials (SEPs) elicited by magnetic nerve stimulation

Magnetic stimulation of peripheral nerves at distal and proximal sites of the upper and lower extremities and at the midlumbar level were used to elicit cortical somatosensory evoked potentials. Evidence is provided that peripheral nerve trunks, rather than distal receptor afferents, are the anatomical structures stimulated by the electromagnetic fields. Magnetic stimulation of peripheral nerves is considered to be useful for an evaluation of the integrity of proximal nerves, nerve roots and central conduction along sensory pathways. In contrast to electrical nerve stimulation, magnetic stimulation is painless and can be applied to proximal nerves and plexus. By means of proximal nerve stimulation central sensory conduction can be tested even in patients with peripheral nerve lesions or polyneuropathy.     

Subject-based P1 latency inter-root comparison,a method to evaluate P1 latency in scalp recorded somatosensory evoked potentials obtained with sensory nerve stimulation in the lower extremities

The purpose of the present study was to establish a method that allows the general use of subject-based criteria to evaluate P1 latency in scalp recorded somatosensory evoked potentials obtained with stimulation of the sural (S1), superficial peroneal (L5) and saphenous (L4) nerves bilaterally. The nerves were stimulated at the same distance from the registration electrode.Two groups of normal nerve roots were studied: (1) nerve roots on both sides in 20 asymptomatic volunteers, and (2) neuroradiologically normal nerve roots on the asymptomatic side in 22 patients with unilateral sciatica.The results presented show that the P1 latencies after stimulation of the 6 different nerves in the same person can be regarded as equal. On this basis 2 criteria to evaluate P1 latency by within-subject P1 latency inter-root comparison were defined. They were the difference between P1 latency of 1 registration and (1) that of any one of the other 5 registrations and (2) the mean P1 latency of the other registrations.The variability of these subject-based criteria and the width of their reference limits were compared to those of the population-based criteria of height- and height-age-corrected P1 latency. This comparison showed that the use of within-subject P1 latency inter-root comparison should enhance the ability to demonstrate small bilateral P1 latency prolongations at the same segmental level.     

Focal potentials of Clarke's column neurons

In experiments on cats, we investigated focal potentials of Clarke's column neurons and discharges of individual neurons recorded extracellularly. An ultrasonic scalpel was used to remove the part of the spinal cord between Th₁₃ and L₃, and an electrode was inserted into the face of the caudal segment of the spinal cord along the axis of Clarke's column. Orthodromic excitation of Clarke's column neurons was evoked by stimulating cut nerves of the ipsilateral extremity; antidromic excitation was evoked by stimulating the dorsolateral funiculus, which was preliminarily separated from the removed portion of the spinal cord. It was found that the orthodromic potential, antidromic potential, and discharges are distinctly registered when the method of electrode insertion is used, whereas they were not recorded when the microelectrodes were sunk into the dorsal surface in these experiments. It is demonstrated that orthodromic and antidromic focal potentials of Clarke's column neurons are similar to motoneuron focal potentials with respect to time characteristics. Inversion of the charge sign was recorded with the approach of the microelectrode's tip to the soma of Clarke's column neurons. It is hypothesized that the success of recording focal potentials and extracellular discharges of Clarke's column neurons resulted from the fact that the orientation of dendrites of these cells matches the direction of microelectrode movement. The slender portion of the microelectrode penetrates the interdendritic space, where tension of the extracellular field is the greatest; it then moves through this space to reach the soma.I. P. Pavlov Institute of Physiology, Academy of Sciences of the USSR, Leningrad; A. A. Bogomol'ets Institute of Physiology, Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Neirofiziologiya, Vol. 2, No. 5, pp. 528–535, September–October, 1970.     

The neuronal organization of the limbic (cingulo-)-visceral reflex arc

The paper summarizes new electrophysiological data concerning the structural-functional organization of the limbic cortex and role of the rostral limbic region of visceral functions. Here are presented the results of a series of electrophysiological investigation of the focus of localization in the supracallosal (area 24) and infracallosal (area 25) part of the anterior cingulate gyrus of evoked potentials of maximal amplitude and minimal latent period to stimulation of pelvic, splanchnic and sciatic nerves. It was shown that evoked potentials of maximal amplitude and minimal latent periods to stimulation of viscero-somatic nerves are recorded in the supragenual area 24 in comparison with the infragenual area 25 of the anterior limbic cortex. In a series of microelectrophysiological studies of reactions of neurons of area 24 and 25 it was established that the reactivity of neurons of area 24 is higher than that of area 25. All these data indicate to the leading role of area 24 in reception and treatment of viscero-somatic afferent signals. In series of experiments it was shown that the focus of exciting neurons, forming the descending singular-autonomic discharge is localized in the infragenual area 25 of anterior limbic cortex. In a study of the comparative characteristics of sympathetic responses in lumbar white communicating rami and parasympathetic responses in pelvic nerve it was shown that evoked potentials in pelvic nerve and white rami had the lowest threshold and shorter latency in case of stimulation of area 25. Study of characteristics of influence of dorsal (area 24) and ventral (area 25) regions of rostral limbic cortex on bioelectrical activity of two postganglionic sympathetic nerves-inferior cardiac and vertebral branches of stellate ganglion, innervating coronary vessels and vessels of anterior extremities correspondingly, showed that stimulation of ventral area 25 evoked increase of electrical activity of the two sympathetic nerves and reliable increase of systemic arterial pressure, while stimulation of dorsal area 24 evoked decrease of tonic activity of the two sympathetic nerves and reliable decrease of systemic arterial pressure. In the paper are presented also the results of microelectrophysiological investigation of peculiarities of reactions of inspiratory and expiratory neurons of bulbar respiratory center to high frequency stimulation of area 24 and 25--in case of stimulation of dorsal area 24 the prevailing effect is suppression of spike activity of neurons, of stimulation of ventral, infragenual area 25 the prevailing influence is excitatory. In another series of microelectrophysiological experiments it was shown downward blocking inhibitory influence of dorsal supragenual area 24 of anterior limbic cortex on activity of vagal viscerosensory neurons of bulbar solitary tract nucleus. It is concluded that the strictly connected one another areas 24 and 25 of limbic cortex are functionally differentiated: the infra-limbic cortex is mainly a viscero-motor cortex, while the prelimbic area 24 plays a leading role in reception and treatment of viscero-somatic afferent information.     

Waveform Similarity Analysis: A Simple Template Comparing Approach for Detecting and Quantifying Noisy Evoked Compound Action Potentials

Experimental electrophysiological assessment of evoked responses from regenerating nerves is challenging due to the typical complex response of events dispersed over various latencies and poor signal-to-noise ratio. Our objective was to automate the detection of compound action potential events and derive their latencies and magnitudes using a simple cross-correlation template comparison approach. For this, we developed an algorithm called Waveform Similarity Analysis. To test the algorithm, challenging signals were generated in vivo by stimulating sural and sciatic nerves, whilst recording evoked potentials at the sciatic nerve and tibialis anterior muscle, respectively, in animals recovering from sciatic nerve transection. Our template for the algorithm was generated based on responses evoked from the intact side. We also simulated noisy signals and examined the output of the Waveform Similarity Analysis algorithm with imperfect templates. Signals were detected and quantified using Waveform Similarity Analysis, which was compared to event detection, latency and magnitude measurements of the same signals performed by a trained observer, a process we called Trained Eye Analysis. The Waveform Similarity Analysis algorithm could successfully detect and quantify simple or complex responses from nerve and muscle compound action potentials of intact or regenerated nerves. Incorrectly specifying the template outperformed Trained Eye Analysis for predicting signal amplitude, but produced consistent latency errors for the simulated signals examined. Compared to the trained eye, Waveform Similarity Analysis is automatic, objective, does not rely on the observer to identify and/or measure peaks, and can detect small clustered events even when signal-to-noise ratio is poor. Waveform Similarity Analysis provides a simple, reliable and convenient approach to quantify latencies and magnitudes of complex waveforms and therefore serves as a useful tool for studying evoked compound action potentials in neural regeneration studies.     

Mechanical responses of the rat uterus, cervix, and bladder to stimulation of hypogastric and pelvic nerves in vivo

Mechanical activities of the uterus, cervix, and bladder were recorded in vivo in anesthetized rats during electrical stimulation of either the hypogastric or pelvic nerve. Ovariectomized controls and hormone-treated groups were used as well as pregnant and postpartum rats. Stimulation of either hypogastric or pelvic nerve produced voltage- and frequency-dependent contractions of the three organs with no evidence of apparent inhibition. All evoked responses were completely abolished by tetrodotoxin, suggesting that these nerves are common pathways of innervation to the three organs. Atropine abolished uterine and cervical responses to both hypogastric and pelvic nerve stimulation, whereas bladder responses were only partly reduced. Hexamethonium almost totally blocked the evoked responses of the uterus and cervix. Phentolamine partly blocked uterine and cervical responses, and propranolol or physostigmine enhanced uterine and cervical responses to both hypogastric and pelvic nerve stimulation. These results suggest that motor innervation to the rat uterus and cervix is predominantly postganglionic cholinergic, with some alpha- and beta-adrenergic components, and that the bladder is innervated by mainly cholinergic and also noncholinergic nerves. Estrogen and estrogen-plus-progesterone pretreatment significantly increased the responses of uterus and cervix but not bladder. Uterine and cervical responses to either hypogastric or pelvic nerve stimulation were markedly reduced late in pregnancy and reappeared within 7 days after delivery.     

Cerebral responses elicited by stimulation of the vesico-urethral junction (VUJ) in diabetics

To investigate the involvement of the visceral afferent nerves in diabetes mellitus, we enrolled 46 male patients in a study, examining the cerebral potentials evoked by stimulation of the vesico-urethral junction (VUJ CEP) and the pudendal (penile CEP) and posterior tibial nerves (tibial CEP). The age range was 23–67 (mean 45.8) years. The epithelial surface of the vesico-urethral junction was stimulated bipolarly with an electrode attached to a specially produced Foley catheter. Cerebral responses were recorded bipolarly at vertex.VUJ CEPs were absent (27 patients) or protracted and/ or of low amplitude (4 patients) (total 31 patients; 67.8%). Penile CEP and/or tibial CEP could be obtained in all cases; however, protracted P1 peak latencies were detected in 15 (32.8%). The abnormalities of VUJ CEP did not correlate with the presence of peripheral neuropathy, while the abnormalities of penile CEP and/or tibial CEP invariably coincided with the presence of peripheral neuropathy. Although neither age nor the duration of diabetes correlated with abnormal CEPs as determined by any of the tests, insulin dependence correlated with abnormal penile CEP and to a lesser extent with VUJ CEP.We conclude that VUJ CEP is informative in evaluating the physiological condition of visceral afferents, and can be used in diagnosis of the early involvement of visceral afferents in diabetes mellitus.     

Noncholinergic Transmitter(s) Maintains Secretion of Catecholamines from Rat Adrenal Medulla for Several Hours of Continuous Stimulation of Splanchnic Neurons

The effect of continuous stimulation of splanchnic nerves at 1, 3, and 10 Hz on the secretion of catecholamines from the isolated rat adrenal gland was examined. Secretion evoked at 10 Hz declined over 60% in 1 h, and by the end of 4 h the secretion was only 10% of the initial value. The secretion evoked at 3 Hz was unchanged in the first hour, but showed a gradual decline in subsequent hours. In contrast, secretion evoked at 1 Hz was well maintained for several hours. Even after 6 h of continuous stimulation, the decline was only about 35%. Atropine plus hexamethonium reduced the secretion evoked at 10 Hz by over 80%, but that evoked at 1 Hz was reduced by about 35%; addition of naloxone reduced it to 75%. When the secretion declined to very low levels after continuous stimulation at 10 Hz for 100 min, a change in frequency to 3 Hz or 1 Hz caused a sharp rebound in the secretory response. Returning the frequency back to 10 Hz led to a sharp drop in the secretion, whereas reducing the frequency to 1 or 3 Hz once again increased the secretion. The rebound in the secretory response after switchover of frequencies was observed in the presence of atropine plus hexamethonium, but was abolished by naloxone. Extensive stimulations, which caused large amounts of catecholamine secretions at each frequency, were not associated with any loss in tissue catecholamine contents. The major conclusion is that secretion of catecholamines is maintained uninterrupted for several hours when splanchnic nerves are stimulated at low frequency.(ABSTRACT TRUNCATED AT 250 WORDS)     

千频交流电刺激在外周神经传导阻断中的作用

感觉、运动或自主神经系统的异常病理活动与疼痛和痉挛等多种神经机能障碍有关。千频交流电（kilohertz frequency alternating current，KHFAC）刺激是一种阻断异常病理活动在外周神经内传导的有效方法，它在缓解相关神经机能障碍方面具有临床应用潜力。KHFAC产生的神经传导阻断受千频信号波形和参数、阻断电极设置和位置以及神经纤维类型和直径等因素影响，具有快速性、可控性、可逆性、局部作用和副作用小的特点。但是，在产生完全传导阻断前，KHFAC首先在靶向神经上激活一簇高频初始放电，这种初始响应可能导致肌肉抽搐或疼痛感。同时，在撤去KHFAC后处于阻断状态的靶向神经需要经历一段时间才能恢复正常传导能力，这是该技术导致的后续效应。目前，关于KHFAC阻断神经传导的生物物理机制假说包括千频信号诱发K⁺通道激活和Na⁺通道失活。本文首先介绍了KHFAC技术的电生理实验研究方法和计算模型仿真方法，然后综述目前关于KHFAC作用下神经传导阻断的研究进展，重点论述初始响应特性及消除方法、传导阻断的后续效应、刺激波形和参数的影响、电极设置与位置的影响以及该技术潜在的临床应用，同时归纳KHFAC阻断神经传导的生物物理机制，最后对该技术未来的相关研究进行展望。     

The mechanism of [3H]noradrenaline release by histamine and its analogs from the rat vas deferens

In this study the mechanism by which histamine and H1 and H2 agonists evoked an overflow of radioactivity from rat vasa deferentia preloaded with [3H]noradrenaline was investigated. The overflow evoked by the various agonists was unaffected by the presence of such receptor antagonists as propranolol, phentolamine, cimetidine, or scopolamine. On the other hand, the overflow evoked by all agonists except dimaprit was inhibited by mepyramine and by two well-known neuronal uptake inhibitors, cocaine and desipramine. The inhibition by mepyramine has been attributed to its effect on the neuronal uptake process. Metabolic profile studies showed that 3,4-dihydroxyphenylglycol (DOPEG) was the major constituent in the evoked overflow caused by histamine, 2-methylhistamine, 4-methylhistamine, and dimaprit and that the overflow evoked by 2-pyridylethylamine and 2-thiazolylethylamine consisted predominantly of unchanged noradrenaline. Based on these findings, it is concluded that all of the agonists tested evoke noradrenaline release intraneuronally by entering the adrenergic nerve terminals. While dimaprit might enter by passively diffusing into the adrenergic nerves, other agonists seem to use the neuronal uptake process. Noradrenaline released intraneuronally is subsequently degraded by neuronal monoamine oxidase to form DOPEG. However, there are qualitative and quantitative differences in the metabolic profile of the overflow evoked by various agonists. It is suggested that these differences could arise from their additional properties, such as their effect on the neuronal uptake process and (or) their ability to act as substrate for neuronal monoamine oxidase.     

Catecholamines abolish vagal but not acetylcholine tone in the intact cat trachea

To obtain evidence in the airways that catecholamines inhibit cholinergic neurotransmission, we recorded transverse tension in the posterior wall of an upper tracheal segment in anesthetized cats and compared the inhibitory effect of stimulating cervical sympathetic nerves when segment contraction was evoked by endogenous acetylcholine (vagal tone) with the effect when contraction was evoked by exogenous acetylcholine applied directly to the mucosal surface of the tracheal segment (ACh tone). We found that sympathetic stimulation abolished all contraction evoked by vagal tone but reduced ACh tone by only one-half. In a second group of cats we compared the inhibitory effects of sympathetic stimulation and intravenous isoproterenol during vagal and ACh tone and also during tone evoked by exogenous 5-hydroxytryptamine (5-HT tone). Sympathetic stimulation or isoproterenol injection abolished all vagal and 5-HT tone but again reduced ACh tone by only one-half. Our results suggest that catecholamines released from sympathetic nerves or injected into the circulation completely inhibit vagal tone. This inhibition may be partially responsible for inducing relaxation in airway smooth muscle.     

Acetylcholine--inhibition of transmitter release from adrenergic nerve terminals mediated by muscarinic receptors.

The evidence is reviewed for the presence of muscarinic receptors on the sympathetic nerves to blood vessels. Activation of these receptors by acetylcholine in doses that are too small to affect the smooth muscle cells directly inhibits the release of norepinephrine evoked by electric impulses or potassium ions. This inhibitory action of acetylcholine is prevented by muscarinic blocking agents and is probably due to hyperpolarization of the adrenergic nerve terminals.     

An improved electrode design for en passant recording from small nerves

1. A modification of the oil and hook electrode technique for recording extracellularly from fine nerves is described. 2. It uses a fine hook and a plastic tube that can be manipulated independently, and through which a high-viscosity oil or grease may be forced over the nerve. 3. The suitability of the electrode for high-quality and long-term recording is discussed.     

The latency difference of the tibial and sural nerve sep: Peripheral versus central factors

The latency of the cortical SEP (CSEP) following stimulation of the posterior tibial nerve is nearly always shorter than the latency of the CSEP evoked by stimulation of the sural nerve. Till now this fact was believed to be due mainly to different conduction velocities within the peripheral nerves owing to the muscle afferents of the posterior tibial nerve. The surprising discovery that the lumbar and cervical SEPs exhibit much shorter time lags than the CSEPs led to the experiments described in this paper: during the registration of the peripheral sciatic nerve action potentials only slight differences in the conduction velocities were observed. Thereupon a topographical analysis was performed during which the minimum latency of the sural nerve CSEP was not measured at the usual C′_z electrode position but was found to be shifted to a more occipital and ipsilateral point.From these results it was concluded that, for the main part, the latency difference of the CSEPs results from ‘central factors’, which had already been postulated for the median nerve CSEP by Burke and coworkers.     

Reflex control of posterior shoulder muscles from arm afferents in healthy people

In order to position the hand during functional tasks, control of the shoulder is required. Heteronymous reflexes from the upper limb to shoulder muscles are used to assist in this control. To investigate this further, the radial and ulnar nerves were stimulated at elbow level whilst surface electromyographic activity of posterior deltoid, infraspinatus and latissimus dorsi muscles were recorded. In addition, the cutaneous branch of the radial nerve and the skin of the fifth digit were stimulated in order to investigate any cutaneous contribution to reflex activity. Reflexes were evoked in all three of these shoulder muscles from hand and/or forearm afferents. However, the reflexes differed; whereas both excitatory and inhibitory reflexes were evoked in posterior deltoid and infraspinatus, the reflexes in latissimus dorsi were mainly excitatory. Cutaneomuscular reflexes were seldom evoked here, but when they were present they were generally evoked at longer latencies than the reflexes evoked by mixed nerve stimulation. The results suggest a role for reflexes originating from the forearm and/or hand in the control of the shoulder.