Dark Discharge Research Articles

The visual properties of rat and cat suprachiasmatic neurones

1. Responses of single neurones in the suprachiasmatic nuclei (SCN) were recorded in the anaesthetized rat and cat. Visual SCN units in both species were predominantly present in the caudal half of the nucleus. The large majority could be classified as either tonically suppressed or tonically activated according to whether an increase in diffuse adaptation luminance respectively decreased or increased their mean discharge rate. 2. For both the cell types the maintained discharge at different luminance levels was a monotonically decreasing or increasing function over a large range of light intensities. In both species the threshold for luminance-dependent maintained discharge was high (>−1 log cd·m−2). The observation of either cell type was independent of the phase of the circadian cycle but it was not established whether the same held true for the intensity-response relations. 3. A small proportion of suppressed cells in the rat SCN reflected the state of retinal adaptation in their firing rate. After light adaptation these cells attained their steady state dark discharge only very slowly. 4. The receptive fields of cat SCN cells tended to be large (> 20°) without a clear antagonistic centre-surround organization. It is proposed that the receptive fields of SCN are the result of the convergence of retinal input from tonic W-cells. 5. It is concluded that their characterization as detectors of diffuse temporal luminance gradients makes visual SCN neurones particularly suitable for their function in the photic entrainment of circadian rhythms. This functional specialization is probably common to both the direct retinofugal projection and the indirect visual projection via the ventral lateral geniculate nucleus to the SCN.

Retinal ganglion cell activity in the ground squirrel under halothane anesthesia

Retinal ganglion cell activity in the predominantly cone retina of the ground squirrel was studied under conditions of light halothane anesthesia with intensive controls and/or monitors of the animal's physiological state. Maintained dark discharge was comparable to what has been found in other mammalian retina. Only one kind of color opponent retinal ganglion cell—designated the BG-G unit—was found when the preparation was physiologically normotensive. The BG-G units converted into two other forms of color opponents when the preparation's blood pressure became hypotensive. The change was reversible.

Receptive field properties of single units in the opossum striate cortex

On the basis of their trigger-features, 98 units out of 127 recorded in striate cortex of immobilized opossums, under forced breathing of a nitrous oxide/oxygen mixture, were classified into 5 receptive field groups. Group 1 units (20/127) responding to small stationary spots were shown to be made up of regions of opposite response type and mutual antagonism, separate by linear boundaries. The optimal discharge was elicited by a stimulus configuration consisting of rectilinear regions of opposite contrast positioned and oriented in the visual field so as not to elicit antagonism while maximizing the overlap with regions responsive to that contrast. To edges in motion these units were shown to be made up of light and dark discharge centers, the locations of which could not be predicted from the map to stationary spots. In addition to position and orientation, direction was another important stimulus parameter. Group 2 units (34/127) had uniform requirements of stimulus orientation, direction of motion or both, througout the receptive field. Width was rarely a significant variable. Three subgroups were detected: orientation selective, directional selective and orientation-direction sensitive. Group 3 units (18/127) required stopped stimuli. In most instances (14/18) this property was attributed to a suppressive surround with relatively non-specific stimulus requirements. Oriented and non-oriented responsive receptive fields were observed. Group 3 units with no surround (4/18) responded best to properly positioned and oriented wedges, usually of 90 degrees. Group 4 units (24/127) had uniform fields with little stimulus specificity and were often responsive to diffuse light. Although not sensitive to stimulus orientation and direction, motion was frequently a requisite for optimal responses. Group 5 receptive fields (2/127) had concentrically arranged regions of distinct response type which displayed mutual antagonism. No sensitivity to orientation or direction was detected. Twenty-nine units remained unclassified. Other group distinctions were the relatively higher spontaneous activity of group 4 units and the large field sizes encountered among groups 1 and 4 when compared to group 2. Based on their properties and receptive field type distribution, we propose that striate receptive fields in the opossum have a similar organization to those of other mammals.

Spontaneous and light-induced compound action potentials in the isolated eye of Aplysia: Initiation and synchronization

(1) The isolated eye of Aplysia shows a bursting pattern of spontaneous compound action potentials (CAPs) in the dark. The ‘light response’, also composed of CAPs, may be separated into a phasic initial response and a tonic late response similar in form to the dark discharges when the illumination is of low intensity. (2) Blockage of chemical synapses with La 3+ or hi Mg 2+-lo Ca 2+ stops the dark discharge and tonic light response but not the phasic light response. Synchrony of the CAPs is not affected. (3) Ca 2+-free solutions produce continuous rapid firing of CAPs, seldom coordinated into bursts. (4) Replacement of chloride by propionate abolishes all CAPs for several hours, but leaves the ERG intact and the optic nerve electrically excitable. (5) Low sodium levels (about 50% normal) suppress dark discharge and tonic light activity but allow a normal phasic light response. (6) It is concluded that receptors transmit light-induced excitation to a higher order neuron population via electrical junctions, and that synchrony of the CAPs is also due to electrical junctions, interconnecting the higher order population. One or more pacemaker cells are postulated to drive the higher order neurons by chemical synapses, producing the dark discharge and the low intensity tonic light response. The pacemaker mechanism may be sodium dependent.

Unified positive column theory of gas discharges

The effects of electron impact ionization, three-body recombination, and a thermal energy balance are considered on the positive column of a gas discharge confined between plane parallel walls. The diffusion flux equations (with temperature-dependent ionization and recombination) for conservation of ions and electrons, Poisson's equation for the self-consistent electric field, and the Elenbaas-Heller energy equation for the temperature distribution, are used. Thermal and electrical conductivities are given by mixture rules that are linear interpolations of collision cross sections in fraction ionized. This formulation allows the description of the entire range of gas discharges from dark discharges through arcs. The emphasis here is devoted to the range from the normal glow through the transition to an arc. The end result is the calculation of semi-internal characteristics, ionization collision rate versus current (per unit depth), and electric field versus, current (per unit depth). It is found that the ionization rate has a maximum and the electric field a minimum in the arc domain.

The neuronal dark discharge during eye movements in awake ‘encéphale isolécats

(1) Transient increases in the neuronal dark discharge of the central visual pathways (geniculo-cortical tract and corticofugal radiation), as well as of single lateral geniculate units, have been observed time-locked with eye movements during wakefulness in ‘encéphale isolé’ cats. These changes were accompanied by the appearance of a distinctive wave pattern in the visual cortex, while no change has been seen in the activity level of the optic chiasm fibers. (2) These increases in central visual impulse traffic have been found to be always bilateral. No direct relationship between the amplitude of a transient increase in central visual activity and that of an eye movement could be observed. Only active and bilateral eye movements with fast rising phase in the electro-oculogram were found to be related to the central visual events. (3) In our awake ‘encéphale isolé’ cat preparation, the central visual phenomena could be present without a corresponding or detectable eye movement in the electro-oculogram. When a more sensitive index of the motor activity, such as the electromyogram of the extrinsic ocular muscle involved in the movement or the neuronal activity of an oculomotor nucleus replaced the electro-oculogram, the central visual phenomena were always found to be accompanied by the oculomotor activation. (4) The observed phasic increases in central visual firing rate have always followed the oculomotor activation. Evidence has been achieved that the central visual phenomena synchronous with eye movements are not depending upon peripheral inputs from the eye. (5) These transient changes in central visual activity might represent that central discharge concurrent with the efferent discharge resulting in an active eye movement postulated in an attempt to explain distinctive perceptual phenomena during active eye movements.

Palm fronds and animal jaw in the vagina mimicking advanced cancer of the cervix

Herbal intravaginal medications are not uncommon in northern Nigeria, often used as aphrodisiacs or less commonly, to treat infective gynaecological conditions. Most of these medications are self-inserted. We report an unusual case of a 20-year-old patient with sickle cell disease with primary infertility who was referred from a general hospital with both clinical and radiologic evidence of advanced cancer of the cervix, for expert management. Speculum examination revealed copious dark frothy malodorous vaginal discharge with a huge necrotic irregular cervical mass extending to the upper two third of the vagina. Digital pelvic examination performed to clinically stage the tumor revealed the mass was made up of organized palm fronds and animal jaw, which were probably inserted for the patient 2 months ago as a therapy for primary infertility. The herbs were evacuated to reveal ulcer craters on the cervix, which bled on contact. Patient responded to antibiotic therapy and is being followed up in our clinic for the primary infertility.

Comparison of effects of eye movements and stimulus movements on striate cortex neurons of the monkey.

AN IMAGE MOVES with respect to the retina both when our eves move a nd when the object moves, but in one case we perceive a stationary object, in the other case a moving object. How can we tell the difference? One approach to this question was proposed by Helmholtz (10) over a century ago. He suggested that when efferent impulses go to the eye muscles, other impulses go simultaneously to areas within the brain. The impulses to the brain would indicate that an eye movement is occurring and that movement of the image with respect to the retina is due to movement of the eye and not to movement of the object. W. James (12) vigorously disputed this hypothesis, but similar hypotheses have been suggested to explain how an insect differentiates between its own movement and movement generated by external forces (1 1), why salamanders make continuous circling movements after eye rotation (Is), and how stability of perceived space is maintained in man (19). The impulses from a motor area to a sensory system have been referred to as a “corollary discharge” (18, 19). If such a corollary discharge exists, one would expect to see a difference at some point in the visual system in the neural response depending on whether the retina moves past a stationary image or whether the image moves across a stationary retina. The purpose of the present experiments was to see whether in striate cortex neurons there is any difference between the response to rapid eye movements across a stationary stimulus and the response to rapid stimulus movements across a stationary eye. A brief report of these experiments has been published previously (22).

Type of response to steady illumination and level of neuronal dark discharge in the central visual pathways

(1) In anesthetized (Nembutal) and unanesthetized pretrigeminal cats the possibility of predicting the direction of the change in frequency of the maintained discharge in response to steady, diffuse illumination was investigated in geniculocortical (G.C.) and corticofugal (C.F.) fibers. (2) In a selected population, it was found that the direction of the change in frequency during illumination was conditioned by the level of the discharge during the immediately preceding dark adaptation period. (3) When the whole population of G.C. and C.F. fibers was considered, the direction of the change in frequency of the maintained discharge was found to be conditioned entirely by the level of the discharge during the preceding dark adaptation period only when the mean frequency of the discharge in the dark immediatel preceding the illumination was higher than the mean frequency of the discharge calculated over all the dark periods of that particular fiber. In the opposite case, the relationship was present only in 50% of the trials. (4) The occurrence of a statistical correlation between the levels of the maintained neuronal activities in dark and light adaptation and the possibility of expressing the prediction in numerical form are discussed.

Aging of Vitreous Arsenic-Selenium Photoconductors

Vitreous arsenic-selenium photoconductors have been observed to age with resultant decreases in spectral sensitivity, dark discharge rate, and residual potential. The first two changes are attributed to surface oxidation of arsenic and the residual potential decrease to a bulk phenomenon. Vitreous selenium photoconductors also exhibit a decrease in dark discharge rate while aging. Removal of the surface layer of an aged As-Se film restores the dark discharge rate and spectral sensitivity to virgin values. Various techniques have demonstrated a change in surface morphology while aging. The effects of atmosphere and temperature on the rate and extent of aging support the surface oxidation model.

Single unit activity in the visual pathway of the butterfly Heliconius erato

Extracellular potentials were recorded from the optic lobes, protocerebrum, and ventral nerve cord of the neotropical butterfly Heliconius erato adanis. Except for pure ‘on’ and ‘off’ fibres, all neurons demonstrated a dark discharge. Neurons demonstrating a special sensitivity to unidirectional movement, jittery movement, dimming, unilateral stimulation, illumination level, etc., were studied. It is questionable whether neurons responding to such stimuli are homologous in all insects. A hypothesis concerning the neural processing of colour information is presented.

Integration of visual stimuli by the crayfish central nervous system.

ABSTRACT For the crayfish, properties of visually reacting intemeurone types in the optic nerve are described on the basis of single-unit analysis. Sustaining fibres show : (a) ‘surround’ inhibition over the whole retina, including the excitatory field; (b) ‘on’ and ‘off’ effects at field boundaries; (c) a dark discharge in deteriorated preparations; (d) an increase in adapted firing rate and response to flashes in an ‘excited state’ of the preparation; (e) increased overall impulse frequency to fast-moving shadows at frequencies of 2–10/sec. which elicit short bursts. Dimming fibres, having mainly reversed properties, show: (a) bursts followed by adaptation to a lower ferquency level of spikes on light dimming; (b) total inhibition by illumination for times proportional to light intensity; (c) responsiveness to quickly moving shadows. ‘Jittery’ movement fibres lack directional sensitivity. Forthem: (a) total illumination and contrast have, within a wide range, no effect on discharges to moving targets; (b) large, dark cards moved at constant speed are seen only near their visual field boundary; (c) the less predictable the movement of a small dark object is, the longer its excitatory effect lasts; (d) responsiveness of field parts exposed is decreased for long durations; (e) no firing is caused by active or passive eye motions. Space-constant fibres show changed location and size of their excitatory fields with eye position. Their potential visual fields below the horizontal plane are un-responsive, due to inhibition caused mainly by statocyst input. Two eye muscle motor fibres, also under statocyst control, are influenced by fight on the limited sensory fields of two pairs of identifiable sustaining fibres. The two motor fibres, which innervate antagonistic muscles, are reversely excited and inhibited by these fields.

Neurophysiology of the states of sleep.

Neurophysiology of the states of sleep.

The integration of visual stimuli in the rock lobster

Single unit impulses were led off from rock lobster “optic” nerve and compared with those of the crayfish. It was found that the lobster possesses, besides type classes which resemble those of the crayfish, an extra class of movement fibers which react specifically, with little habituation, to approaching objects. In addition, the retina is represented by more fibers in each class than in the crayfish, the numbers still being small (about 24 for the whole retina, as against 14). These fibers have, as in the crayfish, overlapping visual fields and are symmetrical with regard to one or more of the four main eye axes. Rock lobster sustaining fibers differ from crayfish ones in (a) dark discharges, and (b) dependence of surround inhibition on distance. The other class of movement fibers resembles the jittery movement type of the crayfish. The conclusion is drawn that the number of fibers in any class and total number of classes present are correlated with the use the animal makes of visual clues.

Discharge patterns of single geniculate neurons during the rapid eye movements of sleep.

Discharge patterns of single geniculate neurons during the rapid eye movements of sleep.

Slow dark discharge rhythms of cat retinal ganglion cells.

Slow dark discharge rhythms of cat retinal ganglion cells.

Diffuse cortical activation waves during so-called desynchronized EEG patterns.

ArticlesDIFFUSE CORTICAL ACTIVATION WAVES DURING SO-CALLED DESYNCHRONIZED EEG PATTERNSJ. Calvet, M. C. Calvet, and J. M. LangloisJ. Calvet, M. C. Calvet, and J. M. LangloisPublished Online:01 Sep 1965https://doi.org/10.1152/jn.1965.28.5.893MoreSectionsPDF (2 MB)Download PDF ToolsExport citationAdd to favoritesGet permissionsTrack citations ShareShare onFacebookTwitterLinkedInWeChat Previous Back to Top Next Download PDF FiguresReferencesRelatedInformation Cited ByNeuronal excitability control in health and disease: A neurophysiological comparison of REM sleep and epilepsyProgress in Neurobiology, Vol. 25, No. 2Transmission processes in the ventrobasal complex of rat during the sleep-waking cycleBrain Research Bulletin, Vol. 5, No. 5Synaptic potentials in cat's lateral geniculate neurons during natural sleep with special reference to paradoxical sleepNeuroscience Letters, Vol. 16, No. 2The reactivity of the somesthetic S1 cortex during sleep and waking in the ratBrain Research Bulletin, Vol. 4, No. 6Effets de la section des nerfs optiques chez le babouin sur l'activite a type de pointes genouillees et corticales au cours des divers etats de vigilanceElectroencephalography and Clinical Neurophysiology, Vol. 44, No. 6Visual cortical neurons influenced by the oculomotor input: Characterization of their receptive field propertiesBrain Research, Vol. 113, No. 2Electrocorticography of waves associated with eye movements in man during wakefulnessElectroencephalography and Clinical Neurophysiology, Vol. 40, No. 5Absence of ponto-geniculo-occipital (PGO) spikes in ratsPhysiology & Behavior, Vol. 12, No. 2The effect of mesencephalic reticular stimulation on intracellular potentials of cat lateral geniculate neuronsBrain Research, Vol. 61The role of the raphe nuclei in the regulation of ponto-geniculo-occipital wave activityBrain Research, Vol. 58, No. 2Lambda waves evoked by retinal stimulation in the absence of eye movementsElectroencephalography and Clinical Neurophysiology, Vol. 35, No. 1Visual cortical units associated with phasic activity in REM sleep and wakefulnessBrain Research, Vol. 55, No. 2Electrical activity in neocortical projection and association areas during slow wave sleepBrain Research, Vol. 52Multiunit activity with eye movements during fast-wave sleep in catsExperimental Neurology, Vol. 37, No. 2An analysis of the effect of reserpine upon ponto-geniculo-occipital wave activity in the cat*Neuropharmacology, Vol. 11, No. 4Lateral geniculate and occipital cortex spikes with eye movements in awake and sleeping cats: Temporal and functional correlationsExperimental Neurology, Vol. 35, No. 2The neuronal dark discharge during eye movements in awake ‘encéphale isolécatsBrain Research, Vol. 34, No. 2Eye movement potentials in the oculomotor and visual systems of the cat: A comparison of reserpine induced waves with those present during wakefulness and rapid eye movement sleepBrain Research, Vol. 27, No. 2Facilitation of the direct cortical response of the visual cortex in association with rapid eye movement during paradoxical sleep in the catBrain Research, Vol. 26, No. 2Cortical unit activity in sleep and wakingElectroencephalography and Clinical Neurophysiology, Vol. 30, No. 2Posture and the role of vestibular and proprioceptive influences on neocortical, limbic, subcortical and cerebellar EEG activityBrain Research, Vol. 17, No. 2Etude sur les activités electrophysiologiques phasiques chez le ratPhysiology & Behavior, Vol. 4, No. 4De´charge unitaire de la formation re´ticule´e pontique et activite´phasique ponto-ge´niculo-occipitale chez le chat sous re´serpineBrain Research, Vol. 12, No. 1Localization and characteristics of the cortical waves associated with eye movement in the catExperimental Neurology, Vol. 22, No. 4Étude quantitative et organisation en fonction de la vigilance de l'activitéunitaire des diverses régions du cortex cérébralBrain Research, Vol. 10, No. 2Waves associated with eye movement in the awake and sleeping catElectroencephalography and Clinical Neurophysiology, Vol. 24, No. 6Étude sur modèle des méthodes de détection EEGElectroencephalography and Clinical Neurophysiology, Vol. 24, No. 2Localization of the lateral geniculate nucleus monophasic waves associated with paradoxical sleep in the catElectroencephalography and Clinical Neurophysiology, Vol. 23, No. 2Effect of bilateral optic nerve section on visual system monophasic wave activity in the catElectroencephalography and Clinical Neurophysiology, Vol. 23, No. 2Individualisation d'un sommeil à ondes lentes et activité phasiqueBrain Research, Vol. 5, No. 2Electrographic studies on the nature of sleep and wakefulnessPhysiology & Behavior, Vol. 1, No. 3-4 More from this issue > Volume 28Issue 5September 1965Pages 893-907 https://doi.org/10.1152/jn.1965.28.5.893PubMed5867884History Published online 1 September 1965 Published in print 1 September 1965 Metrics

STATISTICAL ANALYSIS OF THE DARK DISCHARGE OF LATERAL GENICULATE NEURONES.

The Journal of PhysiologyVolume 170, Issue 3 p. 598-612 ArticleFree Access Statistical analysis of the dark discharge of lateral geniculate neurones P. O. Bishop, P. O. BishopSearch for more papers by this authorW. R. Levick, W. R. LevickSearch for more papers by this authorW. O. Williams, W. O. WilliamsSearch for more papers by this author P. O. Bishop, P. O. BishopSearch for more papers by this authorW. R. Levick, W. R. LevickSearch for more papers by this authorW. O. Williams, W. O. WilliamsSearch for more papers by this author First published: 01 April 1964 https://doi.org/10.1113/jphysiol.1964.sp007352Citations: 90AboutPDF 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 Citing Literature Volume170, Issue3April 1, 1964Pages 598-612 RelatedInformation

Physical and Chemical Effects at the Anthracene—Electrolyte Interface due to Photoelectrolysis

Processes at the dark hole discharge surface of photoconducting anthracene in contact with aqueous inert electrolyte have been examined. O2 was shown to be consumed and anthraquinone formed due to electrolysis. Directional etching of the (001) discharge surface was shown to occur and related to (010) slip planes which were probably developed during growth from the melt. Significance of defects to current carrier trapping was indicated and possible mechanism of carrier discharge was discussed.

Behaviour of Dark Discharge in Discharge Tube with Ignitor

Behaviour of Dark Discharge in Discharge Tube with Ignitor