Laminar Analysis Research Articles

Laminar analysis of hippocampal potentials evoked by peripheral stimulation

From areas SA1 and SA2 of the dorsal hippocampus of unanesthetized rabbits immobilized with d-tubocurarine a laminar analysis was made of evoked potentials (EP) in response to stimulation of the sciatic nerves. Inversion of the initial surface-positive phase of the EP was observed at the level of the pyramidal layer. The subsequent surface-negative phase reached a maximum value in the layer of basal dendrites of the pyramidal cells. The initial portion was inverted somewhat above the pyramidal layer and reached its maximum value approximately at the boundary of the pyramidal and radial layers. The change in sign of the remaining portion of this component occurred 0.3–0.4 mm deeper than the pyramidal layer. It is suggested that both components of the EP picked up from the hippocampal surface are due to an excitatory postsynaptic potential (EPSP) at the apical (positive phase), and basal (negative phase) dendrites. The positivity in the region of the pyramidal somata appears to be an extracellular reflection of a composite postsynaptic potential (IPSP) generated in this region.

Laminar film condensation from nonisothermal vertical flat plates

Laminar boundary layer analysis of film condensation on vertical flat plates with a general temperature distribution at the surface is presented. Using a variable temperature boundary condition at the surfaces of the plate, the difficulties encountered in the conventional similarity analysis applied to a general temperature variation case, are overcome. Solutions are presented for parametric values of this variable, θ 0, and the heat transfer results are developed. These results are compared with the isothermal case under two types of boundary conditions namely(i) the power-law surface temperature variation and (ii) the exponential surface temperature variation. Further, comparison with forced and free convection results indicates that the heat transfer results are influenced to a maximum extent by the nonisothermal boundary conditions.

Heat and mass transfer in dispersed, two-phase, single-component flow

The process of heat transfer to a two-phase mixture of well-dispersed subliming particles and vapor, flowing over a heated surface, is analyzed. It is shown by a laminar boundary layer analysis that, when the surface-area per unit volume of the particle (or solid) phase is large enough, the phase change dominates the heat-transfer process and hastens the development of the thermal boundary layer. Under these conditions, the thermal boundary-layer thickness not only becomes uniform a short distance downstream from the starting point, but also is substantially less than it would be were the particle phase absent. For such systems, the equations describing the heat-transfer process can be considerably simplified and, if the physical properties of both phases are uniform, a remarkably simple solution results. For systems in which the physical properties are not uniform, a solution involving integration across the boundary layer is developed. The solutions are applicable to developing, as well as fully developed, laminar boundary layers over a flat plate; the solutions also approximate conditions in flow through a tube, provided that the tube radius is large compared to the thermal boundary-layer thickness. The predictions of this theoretical analysis agree satisfactorily with experimental results. With slight modification, the same approach may possibly be applicable for turbulent flow in the boundary layer.

Firing patterns induced by sound in single units of the cerebellar cortex.

1. Unit activities evoked by auditory stimulation in the cerebellar cortex have been studied in the encephale isole cat. Poststimulus-time histograms (PSTH) of 1/sec, click-evoked unit discharges have different response patterns with respect to the onset and time course of unit firing. 2. Units have been classified as type I and type II responses based on their preferred firing time relative to the first surface-negative component (N1) of the click evoked folial response. 3. Laminar analysis of the click evoked slow activity centered on an 8–12 msec negative wave in the molecular layer that corresponded with the N1 surface component. An earlier, sharp, negative-positive sequence was found at depths approaching and deep within the granule cell layer. 4. Units considered to be Purkinje cells based on antidromic stimulation or the appearance of typical climbing fiber responses (CFR's) were found exclusively within the type II unit category. Non-identified click units, including various types of cortical interneurons, were found to be either type I or type II units. 5. Evidence that cerebellar click responses are mediated predominately by mossy fiber afferents derives in part from the inhibitory effect of local folial conditioning stimulation upon N1 waves. In addition, the irregular, recurrent CFR's found in click responsive Purkinje cells were temporally unrelated to the acoustic stimulus. Thus click responses in these units appeared to be initiated by mossy fiber activity.

Hippocampal output and sensory mechanisms

This study was performed with the aim of clarifying the mechanisms of the influence that the hippocampal output during theta rhythm exerts on sensory processes. The hippocampal output was simulated by low-frequency stimulation (single trains of 5 rectangular pulses: 5/sec, 0.5 msec, 3–9 V) of the dorsal part of the hippocampal formation. The changes induced by such output in the responsiveness of primary auditory areas to clicks were studied in curarized cats. Primary auditory responses ipsilateral and contralateral with respect to the hippocampus stimulated were modified when the interval between the last stimulus of the train and clicks ranged from 20 to 45 msec and from 30 to 55 msec respectively. The changes in the contralateral auditory response depended on the fact that stimulation of one hippocampus also involved the commissural activation of the other. Signs of hippocampal facilitation were not observed in medial geniculate responses to clicks. Coagulation of the fornix or of non-specific thalamic nuclei strongly depressed or suppressed the hippocampal influence on auditory responses. Laminar analysis of the small surface positive-negative responses elicited in primary auditory areas by train stimulation of the hippocampus alone showed that the hippocampal output activated the superficial layers of the neocortex.

Electrophysiological maturation of the pyramidal tract in the post-natal rabbit

1. 1. The medullary pyramidal tract of rabbits ranging in age from newborn to adult was stimulated electrically, and the evoked cortical and pyramidal unit responses investigated. 2. 2. The cortical evoked response in the adult consisted of an early positive wave of two components (waves 1 and 2), followed by a negative wave (wave 3). These waves were followed by larger variable waves. 3. 3. Laminar analysis data and the discharge distribution of antidromically activated units indicated that the early positive wave is an intra-cortical event reflecting antidromic invasion of pyramidal cell bodies. Wave 3 was considered to originate in the apical dendrites, and to be partially antidromic in origin, and partially the result of post-synaptic potentials. 4. 4. The cortical evoked response in the newborn rabbit was similar in configuration to that of the adult, but the latency was greatly prolonged, not reaching adult values until animals were 30 days old. The amplitude variability of wave 3 observed in the adult with repetitive stimulation was not present in newborns. 5. 5. Pyramidal units could be activated antidromically in the newborn animals, but no spontaneous firing was seen, and no unit responses to peripheral stimulation could be elicited. Spontaneous cortical units were seen after 3 days of age, but units responding synaptically to stimulation of the pyramid were not seen until 10 days. 6. 6. The ability of responses to follow rapid stimulation was considerably less in the immature animal than in the adult. Pyramidal units in the newborn failed to follow stimulation rates in excess of 50/sec. Immature spikes showed decrease of amplitude with rapid stimulation, and frequent fracturing of the spike. 7. 7. The data suggest that pyramidal tract cells in the newborn animal are excitable, functionally isolated from sensory input, and display different membrane characteristics and greater disparity in the threshold of the individual portions of the membrane than the adult.

Fluid dynamic considerations in the design of slinger seals : E. Reshotko and R. L. Rosenthal, Lubrication Eng., 24 (7) (1968) 303–314; 9 figs., 13 refs.

Centrifugal slinger seal dynamic and thermal design and performance properties determined by laminar flow analysis

Paper 34: A Study of Laminar Convection for Flow down Vertical Annuli

Laminar convection in vertical systems is affected by buoyancy so that it becomes a combination of natural and forced convection. In downflow the buoyancy forces oppose the main flow. The problem has previously been studied for flows in vertical circular tubes and is here extended to flows in vertical annuli with uniformly heated inner surfaces. This configuration retains the simplicity desirable for both analysis and experiment, but also represents quite closely certain practical systems such as flow in nuclear reactors in which cylindrical components are placed axially in vertical coolant channels. Buoyancy forces opposing the main flow cause the fluid to be slowed down near the heat transfer surface until it is eventually reversed. In simple theory this flow reversal is associated with a decrease in heat transfer performance. An experimental study has been performed in a vertical annulus of ¾ in inner and 2¼ in outer diameter using water. Flow visualization by dye injection indicates that while small reversed flows may occur in a stable form, higher buoyancy forces give rise to radial components of the flow. These radial components cause the reversed flow regime to become unsteady and the Nusselt numbers to be higher than those predicted by laminar convection analysis.

Some comments on the laminar compressible boundary-layer analysis with arbitrary pressure gradient.

Some comments on the laminar compressible boundary-layer analysis with arbitrary pressure gradient.

The action of antidromic impulses on the cerebellar Purkinje cells.

1. Antidromic impulses have been set up in the axons of Purkinje cells of the cerebellar vermis by stimulation in the juxta-fastigial (J.F.) region. Most experiments were performed on the normal cat cerebellum, but in nine the cerebellum was chronically deafferented by bilateral pedunculotomy 9-23 days previously.2. Intra- and extracellular recording from Purkinje cells both showed a characteristic inflexion on the rising phase of the spike potential (the characteristic IS-SD inflexion) that presumably signals a delay in invasion between the axon and the large soma-dendritic expansion.3. Laminar field analysis of the antidromic spike potentials showed that the antidromic impulses invaded at least 200 mu of the main dendrites as well as the soma, there being then a steep decrement to the surface. At superficial levels there was even an inverse antidromic spike potential. There appeared to be a synchronous invasion of the soma-dendritic complex, perhaps due to trigger zones of low threshold on the dendrites.4. Antidromic soma-dendritic invasion was modified in the expected manner by a volley in the parallel fibres; there was inhibition of transmission into the soma and up the main dendrites (maximum effect at 200-300 mu depth) due to the inhibitory action of the basket and superficial stellate cells that are excited by the parallel fibres; there was facilitation of transmission in the dendrites at levels superficial to 200 mu due to the direct excitatory action of parallel fibres. Both the inhibitory and excitatory actions had a duration in excess of 100 msec.5. In the chronically deafferented cerebellum a second J.F. stimulation evoked a full size antidromic spike potential at an interval of 3 msec. There was a gradual decline in size down to intervals of about 2 msec, and at briefer intervals, to 1 msec, there was a small residual spike potential that possibly is due to transmission into the Purkinje cell axon collaterals at intervals too brief for soma-dendritic invasion. With repetitive stimulation there was a well maintained soma-dendritic invasion at a frequency as high as 300/sec.6. In the chronically deafferented cerebellum an antidromic volley in the Purkinje cell axons caused a brief inhibitory silence of rhythmically discharging Purkinje cells. It is suggested that this is a direct inhibitory action of the Purkinje axon collaterals, that parallels their direct inhibitory action that has been demonstrated by Ito and collaborators (1964) on the intracerebellar nuclei and Deiters nucleus.7. In the chronically deafferented cerebellum an antidromic volley in the Purkinje axons produced not only the large negative spike potential indicative of antidromic soma-dendritic invasion, but also a later small and slow positive wave that appeared to be closely linked with the negative spike. It is shown how this would arise by current flow into the dendrites that had been depolarized but not excited by the initial antidromic invasion.

Evaporation from falling saline water films in laminar transitional flow

AbstractAn analytical and experimental study was made of the evaporation from pure and saline water films flowing down a heated vertical surface at Reynolds numbers between 160 and 600. Visual observation showed free surface evaporation. Film continuity was poor for pure water, but good for saline water, because of the influence of temperature and salinity on surface tension gradients. Evaporation rates were predicted by (1) a constant‐property boundary‐layer type of laminar analysis; (2) the constant‐property Dukler “eddy” treatment; and (3) a variable property laminar analysis that took into account the boiling point elevation due to salinity. The experimental evaporation rates could be correlated by dimensionless moduli arising out of the laminar analyses, but best quantitative agreement was found with the Dukler eddy treatment.

Results of laminar flow analysis and turbulent flow experiments for eccentric annular ducts

Results of laminar flow analysis and turbulent flow experiments for eccentric annular ducts

Laminar, transitional, and turbulent heat transfer after a sharp convex corner

A flow model lias been previously developed for treating the boundary-layer characteristics downstream of a surface discontinuity. The flow field in the neighborhood of the discontinuity or a sharp corner is divided into three regions: the flow upstream of the discontinuity which is obtained by standard techniques, that immediately downstream which is obtained by expanding both the supersonic and subsonic flow fields upstream of the discontinuity inviscidly around the corner, and that downstream of the discontinuity. The flow in the last region is represented by a viscous nonsimilar sublayer that starts at the discontinuity and by a viscous shear layer that has the profiles immediately downstream of the discontinuity as initial conditions. Based upon this flow model, analysis has been developed using the inner and outer expansion techniques. It is the purpose of this report to improve on the treatment of the laminar analysis and to extend the technique of application of this model to include turbulent and transitional flow downstream of the corner. Finally, the results are compared with some of the experimental data available in the literature. It is indicated that good agreement was obtained.

Electrophysiological studies of hippocampal neurons I. Configuration and laminar analysis of the “resting” potential gradient, of the main-transient response to perforant path, fimbrial and mossy fiber volleys and of “spontaneous” activity

Electrophysiological studies of hippocampal neurons I. Configuration and laminar analysis of the “resting” potential gradient, of the main-transient response to perforant path, fimbrial and mossy fiber volleys and of “spontaneous” activity

Morphological and physiological properties of neurons and glial cells in tissue culture.

Morphological and physiological properties of neurons and glial cells in tissue culture.

Cerebellar rhythmic activity induced by arousal stimulation

1. 1. Morphology, conditions of occurrence and possible mechanisms involved in the production of the rhythmic 20–40/sec activity in the cerebellum (CRA) were analyzed in 43 cats. 2. 2. CRA was induced by ( a) sensory stimulation, ( b) electrical stimulation of the ascending activating system including bulbar, mesencephalic, thalamic and hypothalamic structures, and ( c) electrical stimulation of the frontal cortex. It could not be induced by stimulation of the cerebellar cortex, nucleus lateralis of the cerebellum and brachium pontis. The most effective stimulation was high-frequency stimulation of the bulbar and mesencephalic reticular formation. 3. 3. Topical application of strychnine into the reticular formation as well as systemic strychninization induced tetanus waves which resembled the CRA induced by arousal stimulation. A laminar analysis showed that the same component of the cell layers of the cerebellar cortex was responsible for both CRA and strychnine tetanus waves. 4. 4. There was a marked parallelism between the CRA and the arousal pattern in the cerebrum (low voltage fast wave pattern in the neocortex and regular large slow wave pattern in the hippocampus). The CRA was not observed in the presence of slow and spindle waves or thalamically induced spindle-form after-discharge in the cerebrum. 5. 5. No CRA was found in the cerebellum when the cerebrum showed convulsive discharge induced by electrical stimulation or convulsant drugs. With systemic strychninization, there was a clear distinction between the initial stage (when the CRA and the cerebral arousal pattern were present) and the later stage (when convulsive discharge developed in both cerebrum and cerebellum). 6. 6. There was a striking similarity between the CRA and the train of cerebellar responses evoked by reticular stimulation at optimal frequency (about 30/sec). 7. 7. Rhythmic activity was also observed in the frontal cortex, after arousal stimulation and systemic strychninization. This activity was synchronous with the cerebellar one but of inversed polarity. High frequency stimulation of this same cortical area could induce the CRA as well as cerebral arousal patterns. 8. 8. On the basis of these data it is concluded that the nature of the CRA induced by electrical stimulation and that of strychnine tetanus waves are essentially similar. These two types of CRA are responses to reticular activity which has been enhanced by electrical stimulation or, alternatively, by strychnine. Reticulo-cerebellar connections may be part of the circuit necessary in producing and maintaining these activities.

Feasibility of Turbulent Vortex Containment in the Gaseous Fission Rocket

A semi-empirical analysis was made of the feasibility of containing a gaseous nuclear fuel in a turbulent vortex flow. The analysis is an extension of the laminar diffusion analysis of Kerrebrock and Meghreblian, and includes the experimental information reported by Keyes, concerning the turbulence levels and vortex strengths attainable in jet-driven vortex tubes. It was assumed that the turbulent eddy diffusivity increases the diffusion due to concentration gradients, but has no effect on the diffusion due to pressure gradients. It followed from this assumption that the concentration profile of fissionable gas is broadened, but the position of the maximum concentration is the same as that predicted by the laminar analysis. From the experimental data and this assumption, it was deduced that satisfactory containment of plutonium, or one of its compounds, in hydrogen is possible for certain ranges of the vortex tangential and radial Reynolds numbers. The restrictions imposed on the system by the requirements for nuclear criticality and fission fragment absorption was examined. It was concluded that a vortex reactor providing a significant increase in gas enthalpy over that of the solid fuel nuclear rocket is feasible, however the total system mass is very large, and the thrust to weightmore » ratio is small. Several schemes for increasing the vortex strength, and reducing the turbulence level, are reviewed in the light of these results. Of these, the vortex matrix appears most promising. (auth)« less

An Improved Integral Procedure for Compressible Laminar Boundary-Layer Analysis

A fundamental improvement of any one-parameter integral procedure for compressible laminar boundary-layer analysis is described. It is shown, by means of comparisons with exact solutions covering cases of favorable, zero, and adverse pressure gradients, and of constant and variable surface temperatures with and without heat transfer, that in all cases very significant improvements in the calculated results are attained, and also that this improvement is accomplished simply by evaluating integrals.

Electric potentials occurring around a neurone during its antidromic activation.

ArticlesELECTRIC POTENTIALS OCCURRING AROUND A NEURONE DURING ITS ANTIDROMIC ACTIVATIONPaul FattPaul FattPublished Online:01 Jan 1957https://doi.org/10.1152/jn.1957.20.1.27MoreSectionsPDF (5 MB)Download PDF ToolsExport citationAdd to favoritesGet permissionsTrack citations ShareShare onFacebookTwitterLinkedInWeChat Previous Back to Top Next Download PDF FiguresReferencesRelatedInformation Cited ByPolytrodes: High-Density Silicon Electrode Arrays for Large-Scale Multiunit RecordingTimothy J. Blanche, Martin A. Spacek, Jamille F. Hetke, and Nicholas V. Swindale1 May 2005 | Journal of Neurophysiology, Vol. 93, No. 5Backpropagating action potentials in neurones: measurement, mechanisms and potential functionsProgress in Biophysics and Molecular Biology, Vol. 87, No. 1Functional profile of the giant metacerebral neuron of Helix aspersa : temporal and spatial dynamics of electrical activity in situ13 August 2004 | The Journal of Physiology, Vol. 527, No. 1Intracellular Features Predicted by Extracellular Recordings in the Hippocampus In VivoDarrell A. Henze, Zsolt Borhegyi, Jozsef Csicsvari, Akira Mamiya, Kenneth D. Harris, and György Buzsáki1 July 2000 | Journal of Neurophysiology, Vol. 84, No. 1Modeling Action Potential Initiation and Back-Propagation in Dendrites of Cultured Rat MotoneuronsHans-R. Lüscher, and Matthew E. Larkum1 August 1998 | Journal of Neurophysiology, Vol. 80, No. 2Dipole Theory and Electroencephalography27 August 2016 | Clinical Electroencephalography, Vol. 27, No. 3Dendritic Function: Where does it all begin?Current Biology, Vol. 4, No. 5Synaptically triggered action potentials in dendritesNeuron, Vol. 11, No. 1Spatial distribution of modalities and receptive fields in sensorimotor cortex of awake catsExperimental Neurology, Vol. 107, No. 1Chemical modulation of ephaptic activation of CA3 hippocampal pyramidsNeuroscience, Vol. 17, No. 2Dendrite spikes recorded extracellularly from dorsal horn neuronesBrain Research, Vol. 243, No. 2Antidromic activation of neurones as an analytic tool in the study of the central nervous systemJournal of Neuroscience Methods, Vol. 4, No. 1Effect of membrane polarization and synaptic activity on the timing of antidromic invasionBrain Research, Vol. 181, No. 1Electrophysiologic evidence that deafferentation by dorsal rhizotomy abolishes afferent inputs to segmental levels of the spinal cord in the monkeyExperimental Neurology, Vol. 66, No. 3Intracellular recording of lumbar motoneuron membrane potential during sleep and wakefulnessExperimental Neurology, Vol. 62, No. 3Nerve impulse propagation along nonuniform fibresProgress in Biophysics and Molecular Biology, Vol. 30Spontaneous firing patterns of epileptic neurons in the monkey motor cortexExperimental Neurology, Vol. 40, No. 3Evidence for spike propagation in cortical dendritesExperimental Neurology, Vol. 35, No. 1Field potentials of alpha and gamma motoneurons and Renshaw cells in response to activation of motor axonsExperimental Neurology, Vol. 25, No. 1Inhibitory mechanisms in the rabbit olfactory bulb: dendrodendritic mechanismsBrain Research, Vol. 14, No. 1Extraneuronal potential fields evoked in septal region of cat by stimulation of fornixElectroencephalography and Clinical Neurophysiology, Vol. 24, No. 5Extracellular potential field of antidromically activated CA1 pyramidal neuronsBrain Research, Vol. 3, No. 4Correlation between the morphology and potential field of a spinal motor nucleus in the catElectroencephalography and Clinical Neurophysiology, Vol. 19, No. 2Properties of the pyramidal system in the catExperimental Neurology, Vol. 8, No. 3Electrophysiological studies of hippocampal neurons I. Configuration and laminar analysis of the “resting” potential gradient, of the main-transient response to perforant path, fimbrial and mossy fiber volleys and of “spontaneous” activityElectroencephalography and Clinical Neurophysiology, Vol. 15, No. 3Electrophysiological studies of hippocampal neurons II. secondary postsynaptic events and single cell unit dischargesElectroencephalography and Clinical Neurophysiology, Vol. 15, No. 3Some properties of the afferent pathway in the frog corneal reflexExperimental Neurology, Vol. 7, No. 3Slow waves in the olfactory bulb and their relation to unitary dischargesElectroencephalography and Clinical Neurophysiology, Vol. 14, No. 5Hippocampal electrical activity III. Unitary events and genesis of slow wavesElectroencephalography and Clinical Neurophysiology, Vol. 13, No. 6Septal projections to the dorsomedial thalamic nucleus in the catElectroencephalography and Clinical Neurophysiology, Vol. 13, No. 6Branching dendritic trees and motoneuron membrane resistivityExperimental Neurology, Vol. 1, No. 5Physics of nerve processes5 August 2002 | Reports on Progress in Physics, Vol. 21, No. 1 More from this issue > Volume 20Issue 1January 1957Pages 27-60 https://doi.org/10.1152/jn.1957.20.1.27PubMed13398850History Published online 1 January 1957 Published in print 1 January 1957 Metrics

Natural history of the nerve impulse.

ArticlesNatural History of the Nerve ImpulseGeorge H. BishopGeorge H. BishopPublished Online:01 Jul 1956https://doi.org/10.1152/physrev.1956.36.3.376MoreSectionsPDF (4 MB)Download PDF ToolsExport citationAdd to favoritesGet permissionsTrack citations ShareShare onFacebookTwitterLinkedInWeChat Previous Back to Top Next Download PDF FiguresReferencesRelatedInformation Cited ByThinking about the nerve impulse: A critical analysis of the electricity-centered conception of nerve excitabilityProgress in Neurobiology, Vol. 169Electrophysiological properties of so-called inactivation response and their relationship to dendritic activity in hippocampal pyramidal cells of rabbitsBrain Research, Vol. 130, No. 1II: The cellBiosystems, Vol. 4, No. 2Short latency reticulocortical potentials: Effect of muscarinic anticholinergic drugsNeuropharmacology, Vol. 9, No. 5The relationship of optic nerve fiber groups activated by electrical stimulation to the consequent central postsynaptic eventsExperimental Neurology, Vol. 24, No. 3Electrophysiological studies of hippocampal neurons I. Configuration and laminar analysis of the “resting” potential gradient, of the main-transient response to perforant path, fimbrial and mossy fiber volleys and of “spontaneous” activityElectroencephalography and Clinical Neurophysiology, Vol. 15, No. 3The effects of applied polarization on evoked electro-cortical waves in the catElectroencephalography and Clinical Neurophysiology, Vol. 14, No. 6Dipoles of spontaneous activity in the cerebral cortexExperimental Neurology, Vol. 6, No. 4Oscular contractions in spongesComparative Biochemistry and Physiology, Vol. 6, No. 1Some properties of the secondary discharge in cats' sensorimotor cortexElectroencephalography and Clinical Neurophysiology, Vol. 13, No. 1The effects of curare on cortical activityElectroencephalography and Clinical Neurophysiology, Vol. 13, No. 1Facilitation réticulaire des mécanismes visuels corticauxElectroencephalography and Clinical Neurophysiology, Vol. 12, No. 4 More from this issue > Volume 36Issue 3July 1956Pages 376-399 https://doi.org/10.1152/physrev.1956.36.3.376PubMed13359129History Published online 1 July 1956 Published in print 1 July 1956 Metrics