Activity Of Nerve Cells Research Articles

Histological differences between ventromedial hypothalamic neurones of well fed and underfed rats.

ELECTROPHYSIOLOGICAL recording in the ventromedial hypothalamus has shown that feeding or administering glucose to hungry animals causes an increase in the activity of the cells concerned, whereas lateral hypothalamic activity tends to be lowered1–3. These reactions are consistent with the apparent role of the ventromedial hypothalamus in limiting the intake of food and the lateral hypothalamus in stimulating it4. Histological observations of other parts of the nervous system have shown that increased functional activity of nerve cells can be followed by increases in the size of the nucleoli, and decreased activity by decreases in the size of these organelles5–8. Results reported here show that nucleoli in ventromedial hypothalamic neurones are larger in well fed than in hungry rats.

BRAIN AND CONSCIOUS EXPERIENCE

Experience. Edited by Sir John Eccles. Price, $16.80. Pp 591. Springer-Verlag New York Inc., 175 5th Ave, New York 10010, 1966. This book represents proceedings of a study week at Pontifical Academy of Science in Rome, from Sept 28 to Oct 4, 1964. Sir John Eccles, Nobel Prize winner in Physiology and Medicine in 1963, undertook responsibility of organizing symposium, which included representatives of various neurological sciences, and of editing volume of proceedings. Following Laurentian Conference in 1953, published as Brain Mechanisms and Consciousness, this is perhaps first book to treat same general subject. A group of international experts were assembled to serve as contributors and discussants of various papers. Absent from study week was a professional philosopher. In his preface, Sir John explained that he was instructed by chancellor that the academy by its constitution has for aim to promote study and progress of physical, mathematical and neural sciences and their history. Thus discussion of philosophical questions is excluded. Despite this limitation, philosophical questions abound in papers and discussions, particularly in contributions of Lord Adrian, D. M. MacKay, R. W. Sperry, and H. L. Teuber. Though many of papers present original recent contribu¬ tions from authors' own laboratories, much is in nature of reviews and sum¬ maries. The active researcher will not find much that is new in this volume. Selected topics in neuroanatomy are presented by Colonnier (neocortex) and An¬ dersen (hippocampal formation); and neurophysiology by Eccles (synaptic mecha¬ nisms) and Mountcastle (mechanoreceptive responses). The fifth chapter is Granit's re¬ view of sensory mechanisms as elucidated by work of his laboratory, and that of Hubel and Wiesel. Creutzfeldt and his coworkers summarize some characteristics of nerve cell activity in relation to information transmission in nervous system. Effects of electrical stimulation on threshold of conscious experience in man are reported by Libet. Much of work of Teuber and his students on perception after brain injury is summarized by Teuber. A paper on localiza¬ tion of speech and perception is given by Penfield. The contributions of Jasper and Brenner reflect their continued interest in neural processes underlying various states of consciousness. The starting effects of commissural section are again reviewed by Sperry. Eccles espouses molar view of memo¬ ry mechanisms propounded by Lashley in 20's, and adds to this molecular memory of Hyden. Neural mechanisms in sleep are masterfully reviewed by Moruzzi. A most stimulating discussion of precentrai motor mechanisms in relation to willed movement is given by Phillips (eg, . . electrical stimulation does not . . . evoke natural functioning of cortical neuronal apparatus. . . .). MacKay's contribution re¬ lates information theory to concept of control of action. An essay on brainmind problem (Gomes) and a review of ethological concepts (Thorpe) should close symposium. However, there is appended a paper on dopamine and central neuro¬ transmission (Heymans), and another on psychosomatic problems (Schaefer). Although many of participants repeat¬ edly acknowledge state of ignorance as far as behavior mechanisms is concerned, discussions following each presentation and at end of symposium are gener¬ ally stimulating and literate. The use of rnicroelectrodes in attempts to elucidate neural mechanisms underlying behavior is becoming more and more fashionable, and this is embodied in character of sym¬ posium. I found this research least relevant

Effect of localized cerebellar lesions on the succinoxidase activity of Deiters' giant cells in rabbits subjected to unilateral vestibular neurotomy.

The effect of unilateral vestibular neurotomy combined with a lesion of the cerebellar nodulus on the succinoxidase activity of Deiters' giant nerve cells was studied in 17 rabbits. The succinoxida...

Histochemical observation of bovine spinal ganglia.

Morphologically, large oval cells, small oval cells and intermediate cells were distinguished among the nerve cells of the bovine spinal ganglion. — The nerve cells generally showed the prominent enzymatic reactions to SDH, NAD-, NADP-dependent MDH, GDH and NAD-dependent IDH.— Large cells reacted somewhat slightly to alpha-GDH, G-6-PDH and NADP-dependent IDH, while intermediate and small cells reacted strongly. LDH reaction of large and small cells was moderate and that of intermediate cells varying. — In general, to the dehydrogenases tested, intermediate cells were most stainable and small cells reacted in the varying degrees. Considerable reactions for dehydrogenases were present in the capsular cells especially in the case of NADP-dependent IDH and G-6-PDH. The nerve fibers were less stainable to the dehydrogenases. MAO activity was observed in the capsular cells, nerve fibers and a large number of the nerve cells. — AChE reaction of the nerve cells was various and that of the capsular cells negligible, while ChE activity was limited to the capsular cells. ACP activity in nerve and capsular cells was positive, and ALP activity was confined to the capsular cells and the capillary vessels. Intense ATPase activity was localized in the capsular cells, peripheral zone of the neuroplasm and the neurilemma.

Quantitative observations upon acetylcholine hydrolase activity of nerve cells after axotomy.

Journal of NeurochemistryVolume 13, Issue 12 p. 1549-1550 Quantitative observations upon acetylcholine hydrolase activity of nerve cells after axotomy W. E. Watson, W. E. Watson Department of Physiology University of Edinburgh Medical School EdinburghSearch for more papers by this author W. E. Watson, W. E. Watson Department of Physiology University of Edinburgh Medical School EdinburghSearch for more papers by this author First published: December 1966 https://doi.org/10.1111/j.1471-4159.1966.tb04322.xCitations: 30AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article.Citing Literature Volume13, Issue12December 1966Pages 1549-1550 RelatedInformation

Impulse sequences of thalamic neurons — An attempted theoretical interpretation

1. In the literature interval distributions of thalamic nerve cell activity have been reported, that sometimes showed a preponderance of brief intervals followed by one or more peaks at a longer interval. These results have been compared with those of a model. 2. The model assumes that impulses via two separate channels impinge upon a nerve cell, and that each impulse gives rise to a response. The intervals between impulses in one channel are distributed according to an exponential or exponential-like function, those in the other channel according to a monomodal (or multimodal) function. 3. Interval distributions and expectation density (autocorrelation) functions of the model, based mainly on Monte Carlo simulations, were compared with those experimentally obtained. 4. Some implications of the double input concept are discussed, and methods are indicated for a more thorough investigation of the adequacy of the model.

The pigment in the substantia nigra in parkinsonism: Microspectrophotometric comparison with other sources of human pigment

Using a microspectrophotometer of Pollisted type, visible light curves were determined for the pigment in unstained nerve cells from the substantia nigra in cases of paralysis agitans and from the substantia nigra in controls. The curves from the cases of paralysis agitans were found to be almost identical to those from the controls, a maximum absorption being found at 430 nm. This was also the result with specimens of human retina, skin pigment and melanosis coli. The maximum absorption in the ciliary body, on the other hand, was found at 475 nm. In a specimen from malignant melanoma, curves were found with both these maxima. Lipofuscin gives the same curve as ‘melanin’ (maximum absorption 430 nm), and it is suggested that these pigments perhaps play an active role in the metabolism of nerve cells. Determination at 455 nm of the absorbance of the concentration of pigment in the cells of the substantia nigra, compared with corresponding cells from controls of the same age, showed no difference between the two groups. The size of the nucleolus is likewise the same in both groups. In other words there is no sign of increased nerve cell activity in the substantia nigra in paralysis agitans, but the evaluation in uncertain, as the degree of cytoplasmic basophilia cannot be determined.

Glass-Coated Tungsten Microelectrodes

Unusually rugged microelectrodes for recording the activity of single nerve cells or fibers can be constructed from tapered tungsten wire on which a glass capillary is collapsed and surface bonded. Tip diameter in the range between 1 and 5 microns provides relatively low impedance detection of extracellular potentials.

BINAURAL INTERACTION IN THE ACCESSORY SUPERIOR-OLIVARY NUCLEUS OF THE CAT.

Acoustic clicks were presented through earphones to the two ears of anesthetized cats, and the electrical response activity of single nerve cells in the accessory nucleus of the superior olive was studied. Stimulus parameters investigated included interaural time difference, interaural intensity difference, and average intensity. Attention was concentrated on cells that were excited by stimulation of the contralateral ear and inhibited by stimulation of the ipsilateral ear. The experimental results are incorporated into van Bergeijk's model for binaural interaction, for which it is postulated that localization judgments are obtained on the basis of a comparison of the amounts of response activity in the two accessory nuclei. The model yields predictions that are in agreement with results from human psychophysics. The model predicts that the virtual image should be lateralized toward the side receiving prior or more intense stimulation. A time-intensity trading relationship that is in agreement with results from “centering” experiments is derived. The model predicts minimum detectable changes in interaural time difference of 5–10 μsec and minimum detectable changes in interaural intensity difference of 0.1–0.5 dB.

SUCCINIC DEHYDROGENASE AND RNA IN THE SUPRAOPTIC NUCLEUS AND HYPOTHALAMIC ANTERIOR AREA IN DEHYDRATED RATS.

SummaryA quantitative method that combines an analysis for succinic dehydrogenase activity (SDH) and ribonucleic acid (RNA) content in nerve cells was applied to the supraoptic nucleus (SON) and the anterior area (AA) of the hypothalamus of normal and dehydrated rats. Dehydration resulted in a significant increase in RNA in the SON but not in SDH. In the AA both SDH and RNA increased significantly.We thank Carolyn Dansie for her technical assistance.

Statistical properties of neuron activity in the ascending visual system

1. The activity of single nerve cells in the visual system of cats (curarized or encephale isole preparations) was investigated. Records were sampled from units in the optic tract, the lateral geniculate body, and the striate cortex. The non-sequential interval distribution and the mean discharge rate of spontaneous activity and of that during stimulation of the retina with continuous light was analysed over long periods. An interval analyser was used. 2. The mean discharge rate of spontaneous activity is highest in the optic tract and decreases significantly towards the visual cortex. The mean values are: 35.5 per sec in the optic tract (13 units), 14.0 per sec in the lateral geniculate (24 units) and 5.7 per sec in the visual cortex (145 units). 3. The variety of possible interval distributions was reduced to 3 characteristic types. As belonging to type I those distributions were classified which showed exponential form. Only the frequency of short intervals was reduced, so that the distribution had a peak at 8–10 msec. The joint interval histogram showed that the successive single discharges were independent from each other. From this it could be assumed that spike generation in these cells occurs according to a Poisson-type process. The initial dead time can be explained by the excitability cycle of the units or by recurrent or collateral synaptic interactions. — Bi- or trimodal interval distributions were labelled as type II. The different peaks were attributed to different activity determining factors. A third group (type III) is found by those distributions which show transitional characteristics between the other two. Only one peak of short intervals is distinguishable and flanked by a wide and unsystematic distribution of longer intervals. 4. In the optic tract mainly type I, in the lateral geniculate mainly type II and in the visual cortex almost always type III distributions were found. 5. The interval distribution from each unit in darkness remained essentially the same under continuous illumination, even though the average discharge rate of optic nerve fibers was considerably changed by stimulation. In cortical cells only little changes of discharge rate were induced by continuous illumination of the retina.

On the Enzyme Activities of Motor Nerve Cells in Axonal Reaction

The recent development of enzymocytochemistry encourages further investigation of nerve cells in non-physiological states, applying reliable staining methods of several kinds of enzymes.This experiment aimed to observe the changes of enzymatic activities of chromatolytic motor nerve cells in anterior horn of rabbit spinal cord, in which the retrograde reaction was induced operatively.Observations upon the nerve cells in simply induced chromatolytic state, with reasonable staining controls of normal cells in symmetrical anterior horn, may allow to discuss some possible metabolic conditions of nerve cells in this state.

SPINAL RESPIRATORY NEURONS AND THEIR REACTION TO STIMULATION OF INTERCOSTAL NERVES.

1. Extracellular recordings of the activity of nerve cells in thoracic segments of the spinal cord discharging in rhythmic bursts of action potentials constantly locked to some phase of respiration were carried out in unanesthetized decerebrated cats. 2. One-hundred-and-six respiratory cells were investigated, 55 active during inspiration and 51 during expiration. Both types were encountered at a depth of around 1.0 mm and again at a depth of from 2.0 to 3.5 mm from the dorsal surface of the spinal cord, coinciding roughly with the dorsal and ventral horn. 3. On the basis of their response to electrical stimuli delivered to the ipsilateral, homosegmental intercostal nerve, spinal cord respiratory nerve cells fell into two groups: a) A minority (10 units) could be driven antidromically; b) the majority (96 units) could not. Both groups showed delayed synaptic activation. Units of the first group were considered to be motoneurons; that of the second, respiratory interneurons. 4. Respiratory interneurons could be divided into three classes on the basis of their response to single shocks and repetitive stimulation of the intercostal nerve: a) Units responding to single shock but losing their rhythmic activity during repetitive stimulation at a rate in excess of 5/sec. b) Units responding to single stimuli to the nerve but maintaining rhythmic respiratory activity during repetitive stimulation at rates up to 500/sec. c) Units that did not respond consistently to single shocks to the nerve but only to repetitive stimulation. 5. The response of respiratory interneurons during reflexly induced swallowing consisted of a brief activation, very short (0.15 sec) for inspiratory, longer (1.0 sec) for expiratory internuncial cells. Their rate of discharge during swallowing was found to be higher than that of respiratory motoneurons but lower than that of brain-stem respiratory neurons (cfr. 9).

Aspects of the organization of central nervous pathways in Aplysia depilans.

ABSTRACT There has been little recent work on the relationship between the behaviour of gastropod molluscs and the activity of their nervous systems. Older workers (e.g. ten Cate, 1928), studied the effects of electrical stimulation of different nerves on the movements of parts of the animal. More recently observations on the spontaneous activity and electrical properties of individual cells in isolated ganglion preparations have been extensively carried out (Arvanitaki, 1942; Tauc, 1955, 1957a, b, 1958, 1960a; Hagiwara & Saito, 1959), but little attention has been paid to the importance of these phenomena in the life of the animal. Furthermore, deductions concerning the behaviour of gastropods based on observations of the activity in isolated ganglia are necessarily tentative (Hughes & Kerkut, 1956). The most recent study of neuronal pathways is that of Turner & Nevius (1951) on Ariolimax columbianus. They used external electrodes in stimulation and recording experiments and made tentative proposals concerning the layout of some of the typical neuronal connexions. As they point out, little is known of the connexions between neurones, and anatomical methods are unable to provide sufficient information about the nature of neuronal connexions over long distances. Nisbet (1961) has recently recorded impulses in the pallial nerves of Archachatina in response to tactile stimulation and has studied conduction in the nerves and across ganglia. Techniques similar to those of Turner & Nevius have been used in the present work but in addition intracellular micro-electrodes have been employed for recording the activity of individual cells in whole animal preparations. This technique is extremely valuable as the pattern of activity of single units, now well known from such cells in isolated preparations (Tauc, 1960a), gives additional information about the paths of single neurones over quite large distances.

Some properties of single epileptic neurons.

Previous studies describing the electrical activity at an epileptogenic focus in the experimental animal and man by means of scalp or pial recording with gross electrodes have generally confirmed the concept that abnormal neuronal hyperactivity is the fundamental defect in epilepsy. However, such techniques have been limited by the fact that the potentials recorded are generated by graded response neuronal membranes which, by current concepts, are largely assigned to cortical dendrites. Such studies thus do not yield data upon the activity of those portions of cortical cells generating all-or-none signals. In recent years, microelectrode techniques have been devised which permit the recording of electrical activity of single neurons within the central nervous system. Studies utilizing this technique have therefore been undertaken over the past 8 years to provide information regarding the activity of single nerve cells in epileptogenic foci. Schmidt, Thomas, and Ward 2 carried out microelectrode studies of single

Electrical activity of a giant nerve cell under abnormal conditions.

Electrical activity of a giant nerve cell under abnormal conditions.

'Weightless' micro-electrodes for recording extracellular unit action potentials from the central nervous system.

IN order to record the activity of single nerve cells in the mammalian central nervous system it is necessary to maintain the tip of the recording electrode (a micropipette or metal needle) within some 30µ of the cell body1. The skeleton of the animal is usually rigidly clamped to a heavy metal base and in many experiments this base also carries the micro-electrode upon a rigid support. Unfortunately the exposed central nervous system expands with every beat of the heart and also with exhalation of air from the lungs. Because such movements can make records of unit activity difficult or impossible to obtain, a technique has been developed2,3 for recording from cells in the cerebral cortex in a rigidly enclosed cranial cavity. This system has proved so successful that lengthy records can be obtained from unanaesthetized, mobile animals. There are, however, limitations to this technique. It is not readily adaptable to exploration of a wide area of cortex; moreover, it cannot be applied to an examination of the spinal cord or brain-stem. For this reason we have developed the ‘weightless’ micro-electrode described below.

Integrative Mechanisms in the Nervous System

As long as all-or-none impulses were assumed to be the only changes important for nervous system function, central synapses were supposed to act as on-off switches and even simple integrative actions were ascribed to the complex structural relations between nerve cells. It has now been shown that graded responses occur at synaptic regions and may combine in single nerve cells, facilitating, evoking or preventing generation of impulses. The properties of these graded responses are sufficient to explain some of the processes upon which simple integrative actions are based, and interpretation of complex functions of the central nervous system should now take into account graded activity of nerve cells together with impulse activity and structural organization.

The Effects of X-Rays on the Growth of Spinal Ganglia from 6- and 12-Day Chick Embryos in Tissue Culture

Ionizing radiations have been used in the investigation of a variety of problems relating to development. In the investigation of radiation on embryonic development it soon became evident (1) that the central nervous system is particularly sensitive to roentgen rays. This sensitivity of the embryonic nervous system has been attributed to its mitotic activity, but Hicks (2, 3) suggests that it may be also due in part, at least, to the differentiating activities of young nerve cells. The technique of tissue culture offers a means of direct and continual observation of any experimental manipulation on a group of living cells. Nervous tissue has been maintained in culture by numerous investigators, and the early work has been reviewed by Ashby (4). More recently Levi and Meyer (5-7), Murray and Stout (8), Hogue (9), and Pomerat (10) have studied the activities of nervous tissue in vitro. Radiation effects of explanted nervous tissue, however, have been studied only by Levi and Meyer (6), who observed that there was an inhibition of fibroblastic outgrowth when spinal ganglia were exposed to radium emanation. The following investigation was undertaken to determine the effects of hard Xrays on growth in tissue culture of spinal ganglia of the chick embryo at two developmental levels, namely 6 days' and 12 days' incubation. These two developmental levels were chosen because ganglia from these two groups contain nerve cells which may be considered to be in two stages of differentiation. The younger group contains

Histochemical demonstration of AChE activity in isolated nerve cells.

Summary.A modification of the thiocholine method of Koelle (1951) has been used for the demonstration of the AChE activity in single nerve cells isolated from the surrounding tissue by means of microdissection technique.In neurons in the spinal, sympathetic and parasympathetic ganglions, as well as in the anterior and lateral horns of the spinal cord, large concentrations of AChE could be demonstrated inside the cytoplasm and neurite after a very short incubation time. By using this method the relative amount of such AChE bearing cells was found to be considerably higher than in previous investigations.