Stimulation Of Optic Nerve Research Articles

Inhibitory mechanisms in lateral geniculate nucleus of rat

1. An examination was made of the mechanisms responsible for the inhibition of synaptic transmission through the lateral geniculate nucleus (LGN) of the rat following a single shock to the optic nerve.2. In the rat anaesthetized with paraldehyde we found no evidence that optic nerve stimulation produced any presynaptic inhibition in LGN. In agreement with other workers it was found that repetitive stimulation of visual cortex produced effects attributable to presynaptic inhibition. However, this was of small magnitude in the conditions of our experiments.3. Stimulation of the optic nerve elicited an action potential in a P cell (principal cell) which was followed by a wave of hyperpolarization lasting about 150 msec (inhibitory post-synaptic potential, IPSP, wave).4. The IPSP wave was chloride-dependent and was associated with inhibition of the P cell discharge. Occasional rippling on the IPSP wave suggests that it was produced by the repetitive discharge of I cells (interneurones).5. These observations support the model proposed previously wherein P cells are inhibited by I cells which in turn are excited by axon collaterals of P cells. There is evidence for diffuse interconnexions between P cells and I cells.6. The observation that the extracellularly recorded wave of hyperpolarization (P-wave) is usually negative suggests that most of the inhibitory synapses are not on the soma of the P cell.

Effect of electrical stimulation of the optic nerve on retinal potentials.

Effect of electrical stimulation of the optic nerve on retinal potentials.

Single unit study of post-tetanic potentiation and second subnormality in the lateral geniculate body of cats

Lateral geniculate neurons of anesthetized cats were studied with microelectrodes to determine whether the mechanisms underlying the prolonged depression in synaptic transfer, referred to as second subnormality (SS), which follows optic nerve tetanization occur in presynaptic or postsynaptic elements. Extracellularly recorded excitatory postsynaptic potentials (EPSP) were found to be reduced in amplitude during SS; subsequent tetanization resulted in potentiation of the depressed EPSP followed by a return to depressed levels (SS). During SS, cells which no longer responded to optic nerve stimulation continued to discharge spontaneously at the same rate as they had prior to tetanization, suggesting that tetanization of a portion of the presynaptic inputs to these cells does not alter their responsiveness to other inputs. These findings indicate that SS results from an alteration of presynaptic elements.

SINGLE UNIT STUDIES AND THE MECHANISM OF FLICKER FUSION.

The evidence is reviewed which indicates that the flicker fusion frequency is determined centrally rather than in the eye. The sequence in the cortex of facilitation, inhibition and supranormality after a flash delivered to the eye is described as it is evidenced both in summed and in single unit responses. Inhibition after a flash is more prolonged than after optic nerve stimulation; the difference probably accounts for the discrepancy between the refractory period of single cortical units when tested by paired flashes and by paired stimuli to the optic nerve, and thus accounts for the discrepancy between flicker fusion frequency and the refractory period of neurones. Facilitation of the response of single cortical units to a light flash, by simultaneous stimulation of the optic nerve is described and it is suggested that this mechanism may account for the increase in critical fusion frequency (CFF) when light and electrical pulses are delivered to the eye simultaneously; the time course of facilitation suggests mediation via subcortical centers and the evidence is reviewed which suggests that they may increase the CFF in intact animals and humans.

Evidence supporting cholinergic transmission at the lateral geniculate body of the cat

The neurons in the dorsal nucleus of the lateral geniculate body in encéphale isolé preparations of cats have been activated by orthodromic stimulation of the contralateral optic nerve and by antidromic stimulation of the optic radiation. The evoked geniculate response was recorded by extracellular microelectrodes. Afferent volleys limited to the large fibres the optic tract evoked a diphasic positive-negative presynaptic wave followed after a brief delay of 0·3 msec by a negative postsynaptic wave. Repetitive firing, consisting of several negative waves of small amplitude following the postsynaptic component, was frequently observed in the control preparation. The effects of drugs administered by intracarotid injection were evaluated by noting the amplitude, latency, duration, and refractory period of the geniculate response. Post-tetanic potentiation was studied in control and drug-treated preparations. The postsynaptic component was readily depressed by DHE, depressed to a lesser extent by atropine, and unaffected by d-tubocurarine; it was enhanced by low concentrations of acetylcholine and by physostigmine. Higher concentrations of acetylcholine had a depressant effect. Tetanic stimulation of the optic nerve relieved the depression imposed by DHE and by atropine. It depressed the postsynaptic wave after the wave had been enhanced by low doses of acetylcholine. The presynaptic spike, the antidromic response, and the refractory period remained unaltered after drug administration. 5-Hydroxytryptamine produced a depression of the postsynaptic component which was not relieved by tetanic stimulation. The data evidenced a close resemblance between the pharmacological responses of Renshaw cells and of geniculate neurons and indicate that at least one of the mechanisms subserving transmission in the lateral geniculate nucleus is cholinergic in nature.

Transmission of information in the afferent visual system

The activity of single units of the optic tract, lateral geniculate body, optic radiations and striate cortex was recorded in cats (encephale isole preparations) by means of microelectrodes. The optic nerves or radiations were stimulated with electrical shocks (0.3–1400 per sec). In other experiments binocular light stimuli were used. 1. When 50–200 msec trains of stimuli were applied, the maximal impulse rate transmitted by optic nerve or radiation fibers was found to be between 350 and 1100 per sec. Above these values fiber discharges followed successive stimuli in 1∶2 or 1∶3 ratios. The transmission through a geniculate or cortical synapse reduced this maximal impulse rate to 30–50 percent of that of the fibers. 2. Presynaptic stimulation frequencies above 100–400 per sec were observed to block impulse transmission through the synaptic stations about 10–120 msec after onset of electrical stimulation. Within a small range of stimulation frequency, just below that eliciting blocking, 1∶2, 1∶3 or 1∶4 transmission occured through cortical or geniculate synapses. 3. The maximal impulse frequency transmitted through a neuronal chain decreased as the number of neurons in the chain increased. 4. The information capacity of one afferent channel can be estimated to be 20–120 bit/sec. The information given by a neuronal impulse is not comparable to that of a binary digital unit pulse. Neuronal information can be understood as result of the operation of a system having a pulse frequency modulation code with considerable statistical fluctuation. These considerations do not take in account the added margin of information which is made possible by the spatial and temporal relationships of activity between different channels. 5. The information capacity af the afferent visual system is limited by the frequency properties of synaptic transmission and not by those of afferent fibers. 6. In single cortical units that could be activated by electrical stimulation of either optic nerve, the statistical conditions for “both” — or “either-or” — responses could be demonstrated using bilateral optic nerve stimuli separated by different intervals. 7. With binocular light stimuli summation of excitatory and inhibitory processes were found at the level of cortical neurons. 8. Some neurons in the visual cortex had the capacity of “measuring” the time difference between two light stimuli, one applied to the ipsilateral eye and the other to the contralateral one. 9. The results are compared with the findings of Kuepfmuellee and Jenik regarding transmission and processing of information by an electronic model neuron.

An electrophysiological study of the superior colliculus and visual cortex

In cats anesthetized with Nembutal, simultaneous recording of evoked potentials from superior colliculus and visual cortex to single light flashes gave mean onset latencies of 36.5 msec in the former and 27 msec in the latter. Onset latency to electric stimulation of optic nerve was 8 msec in colliculus and over 1 msec in cortex. Since similar latency differences were obtained from colliculus and cortex.to both retinal (photic) and postretinal (electric) stimulation, latency differences were attributed to slower conduction in the retinocollicular pathway. The thresholds were higher in superior colliculus than visual cortex to light flashes of short duration or low intensity, or electric pulses applied to the optic nerves. Simultaneously recorded collicular and cortical evoked potentials differed from each other in shape, duration, and several other respects. With microelectrodes, three functionally differentiated layers of the superior colliculus were distinguished: a dorsal layer in which evoked potentials and single units responding to optic stimuli were obtained; an intermediate layer in which evoked potentials of unchanged amplitude, but no driven units, were recorded; and a ventral layer in which evoked potentials were greatly reduced, and where only “spontaneously” discharging units were found. The optically driven units were classified as those firing with short latency, with long latency, to light-on only, to light-on and light-off, and those inhibited by photic or optic nerve stimuli.

The inhibitory action of the caudate nucleus in cortical primary receiving areas in the cat

1. I. The caudate nucleus repetitive stimulation (40–100 c/sec, 3 msec) effects on the thalamocortical evoked potentials, in primary receiving areas, were investigated in cerveau isolé or RF lesioned (electrolytic) animals (cats). 1. (a) The visual evoked potential (in gyrus marginalis) elicited by optic radiations, lateral geniculate, optic tract or optic nerve stimulation, was depressed during caudate head stimulation. 2. (b) The auditive evoked potential (in gyrus ectosylvius, areas I, II and in area III, Tunturi) elicited by medial geniculate body stimulation, was depressed during caudate stimulation. 3. (c) The somesthetic evoked potential (along the cruciate sulcus), elicited by VPL stimulation, was depressed during caudate stimulation. 4. (d) The thalamic mid-line nuclei stimulation facilitates all the optic, acoustic and somesthetic evoked potentials, in the same animals in which caudate stimulation depresses them. 5. II. The ascendant caudate influences have been investigated also in animals under light barbiturate anesthesia, comparatively with RF lesioned animals. 6. (a) In this condition the caudate stimulation may sometimes give a double effect, facilitation during the first 1–3 sec, followed by inhibition (during the same stimulation). 7. (b) The stimulation pulse shape changing from rectangular to triangular, with intensities immediately over-threshold, suppresses the facilitatory phase, the inhibitory one persisting. 8. (c) In animals in which a particularly marked facilitation phase to caudate stimulation occurs, electrolytic lesion or trans-section of rostral mesencephalic RF suppresses it. In these conditions, an increase of caudate stimulation intensities gives only an inhibitory effect. 9. III. The inhibition of evoked potentials in the optic, acoustic and somesthetic areas obtained by caudate stimulation is compared with the facilitation of these same potentials, through unspecific thalamic nuclei stimulation and also with the facilitation obtained in Bremer-Stoupel's experiments by reticular stimulation, in order to demonstrate the diffuse ascendent inhibitory action of the caudate nucleus. The caudate activating-like effects obtained sometimes in light barbiturate anesthesia, appear to be mediated through the mesencephalic RF, since its lesion suppresses only this activating phase.

Effect of Optic Nerve Stimulation on the Intraretinal ERG of the Cat

The cat intraretinal ERG was recorded with microelectrodes. Repetitive stimulation of the optic nerve reduced the amplitude of the ERG, especially that of the c-wave. This effect on the intraretinal ERG was tentatively attributed to centrifugal fibers in the optic nerve, although the possibility that it was a secondary effect resulting from an alteration of the retinal circulation could not be excluded completely.

Single units in monkey, Cercocebus torquatus atys, cortex with narrow spectral responsiveness

The responses were recorded of single units in the visual cortex of anesthetized monkeys. The stimuli were brief flashes presented diffusely on the retina through five broad pass color filters in succession. The initial intensity of the flashes was high and nearly equal for the different colors, and the eye was maintained in a steady state of light-adaptation by diffuse white illumination. Of the single units which responded to light flashes, more than half did so to only one of the monochromatic flashes, or to a few adjacent on the spectrum. The response consisted of one or two spikes at all flash intensities. Units with similar response characteristics have not been reported in the geniculate, suggesting that these units are cells whose narrow spectral responsiveness is due to features of cortical organization. When the background illumination was switched off and the eye maintained in the dark for up to 10 min, the responses of most single units tested was unchanged, suggesting that they were connected solely with cone receptors. The responses of the same units to optic nerve stimulation suggested that they lay on a monosynaptic pathway with no evidence of convergence in the central nervous system.

Visually evoked slow negativity in rabbit cortex.

SummaryVisual cortex responses to optic nerve and retinal stimulation were studied by D.C. recording upon slow time line. A prominent slow negative wave (250 to 400 msec. duration), slow negativity, occurred in the wake of primary visual response. Evidence indicates that when activated by nerve stimulation it has a threshold somewhat lower than that of primary response. Under moderately deep Nembutal anesthesia, slow negativity (evoked by optic nerve or light flash stimuli) disappears and is replaced by a longer lasting positive after-effect. The slow negativity described under these conditions is believed to have an origin in the cortex identical with corresponding slow negative waves evoked by direct surface and midline thalamic stimulation. In Fig. 3 it is placed schematically with relation to other components of visual cortical response previously described elsewhere.

ELECTRIC RESPONSE OF VISUAL CENTER TO OPTIC NERVE STIMULATION IN FISH

1) The visual center responses to optic nerve stimulation were recorded by the active electrode leading from the surface of tectum opticum in fishes, chiefly Carassius auratus (L.), typifying the diurnal fish, and Anguilla japonica T. et S. as the nocturnal fish.2) The maximal response in Carassius consisted of the surface negative potential having two components following a surface positive deflection. The later component of the surface negative potential (P 2) has higher threshold than the early component's (P 1). On the positive deflection was superposed two negative spikes representing the action potentials of the pre-synaptic optic nerve fibers. Judging from the results with procaine treatment and with microelectrode recording, the surface negative potential was assignable to the postsynaptic potential.3) The response in eel was made up of only the P 2 as the post-synaptic component.4) The topographic variation in the pattern of the response to the optic nerve stimulation took place by a similar manner as those in the response to illumination of the eye with respect to the appearance of the two components of the post-synaptic potential. Dominant appearance of the P 2 was at the inner side of dorsal aspect of the tectum, and that of the P 1 was at the caudo-lateral region.5) Considering the above two findings and the results on the response to photic stimulation reported previously (1960), it is inferred that the P 1 and the P 2 may correspond to the two post-synaptic components caused by the illumination of the eye, the PSP 1 and the PSP 2 respectively.6) The two components of the post-synaptic potential may represent the activities of different groups of neurons within the center having different physiological nature.7) The post-synaptic potentials failed to follow the repetitive stimuli with the intervals below the absolute refractory period, but the cessation of the stimulation evoked a response. The response induced by the cessation of repetitive stimuli (off-response) increased its size as the intervals of stimuli were decreased, whereas the response following the first stimulus (on-response) tended to be inhibited.8) The P 1 had lower threshold in response to the first stimulus of repe titive stimulation, whereas the P 2 at the cessation of the repetition.9) The mechanism of the generation of the delayed post-synaptic potential caused by the illumination of the eye (PSP 2) as reported previously (1960) was discussed in the light of the present results.

Repetitive stimulation of optic nerve and lateral geniculate synapses

The effects of repetitive stimulation of the optic nerve on the electrical response recorded in the dorsal nucleus of the lateral geniculate nucleus of the cat have been studied. Observations have been restricted to effects on the fast-conducting group of optic fibers. In the main, tetanic frequency has been 500 to 700 per second, and duration of tetanus either 15 sec or 10 min. Tetanic stimulation results in post-tetanic potentiation and depression of both presynaptic and postsynaptic responses. The conditions determining which effect is obtained are described. The presynaptic response during and following the tetanus has been studied, and the excitability of the optic tract and tract nerve endings has been tested by antidromic stimulation. Decrease in excitability of the optic nerve after tetanization is explained on the hypothesis that a hyperpolarization in all parts of the optic fiber follows the tetanus. An increase in amplitude of the presynaptic response also follows the tetanus but can be due only in small degree to an increase in spike height. It is more probably due to slowed conduction and perhaps to a longer duration of action potential in the optic tract nerve endings. The relationship between presynaptic and postsynaptic potential changes after a tetanus is discussed; there is no evidence in these experiments that the size of the presynaptic action potential is the sole or even the main determining factor of the postsynaptic potential changes.

Activation of single lateral geniculate cells by stimulation of either optic nerve.

The lateral geniculate nucleus is organized in such a way that, initially at least, information from the one eye is almost exclusively segregated from that from the other eye. Single-unit recording, however, confirms the histological evidence that bilateral integration does take place. A small number of cells (< 8.5 percent) receive afferents directly from both optic nerves and are discharged by stimulating either nerve (direct interaction). More common is delayed interaction, where the cells are discharged independently by either optic nerve but only after a relatively long latency. Indirect interaction effects also occur.

Post-tetanic potentiation in the visual system of cats.

Post-tetanic potentiation (PTP) has been demonstrated in the soma response of the geniculate and in the positive potentials of the cortex by stimulation of the cat's optic nerve and recording from the lateral geniculate and visual cortex. Within limits, an increase in duration and intensity of tetanus produces an increased amount of PTP which lasts for a longer time. Occasionally the tract response is potentiated. Various explanations are offered to account for this change and the results are discussed in relation to the probable site of action of PTP. In any case the type of PTP examined in these experiments using anesthetized animals appears to be a property of the subnormal phase with a concomitant increase in the subliminal fringe.

Multiple responses and excitability of cat's visual cortex.

ArticlesMULTIPLE RESPONSE AND EXCITABILITY OF CAT'S VISUAL CORTEXLeonard I. Malis, and Lawrence KrugerLeonard I. Malis, and Lawrence KrugerPublished Online:01 Mar 1956https://doi.org/10.1152/jn.1956.19.2.172MoreSectionsPDF (3 MB)Download PDF ToolsExport citationAdd to favoritesGet permissionsTrack citations ShareShare onFacebookTwitterLinkedInWeChat Previous Back to Top Next Download PDF FiguresReferencesRelatedInformation Cited ByDirect stimulation of optic nerve by electrodes implanted in optic disc of rabbit eyes17 September 2004 | Graefe's Archive for Clinical and Experimental Ophthalmology, Vol. 243, No. 1The effects of selective glutamate receptor antagonists on synchronized firing bursts in layer III of rat visual cortexBrain Research, Vol. 599, No. 2Laminar analysis of the origin of the various components of evoked potentials in slices of rat sensorimotor cortexElectroencephalography and Clinical Neurophysiology/Evoked Potentials Section, Vol. 80, No. 4Statistical argument for a presynaptic origin of the second positive component of somesthetic primary cortex evoked potential elicited by central afferent stimulationElectroencephalography and Clinical Neurophysiology/Evoked Potentials Section, Vol. 65, No. 6Selective augmentation of visual pathways by morphine in α-chloralose-anesthetized catsExperimental Neurology, Vol. 77, No. 3The neural circuitry of the neocortex examined in the in vitro brain slice preparationBrain Research, Vol. 243, No. 1Effects of stimulation of the dorsocaudal claustrum on activities of striate cortex neurons in the catBrain Research, Vol. 240, No. 2Membrane characteristics of visual cortical neurons in in vitro slicesBrain Research, Vol. 226, No. 1-2Operant conditioning of vertical eye movements without visual feedback in the midpontine pretrigeminal catBrain Research, Vol. 169, No. 3Visual evoked potential in man: Early oscillatory potentialsElectroencephalography and Clinical Neurophysiology, Vol. 45, No. 6The effects of eye movement and dark-adaptation on transmission through the visual pathways of unrestrained catsBrain Research, Vol. 77, No. 2Evoked potentials of the central visual system during and after hypoxia in catsElectroencephalography and Clinical Neurophysiology, Vol. 36An analysis of sensory interactionNeuropsychologia, Vol. 12, No. 1Early prenatal development of cortical surface responses to visual stimuli in sheepExperimental Neurology, Vol. 37, No. 1Spatial organization of cat visual system. II: Topology and interaction in geniculo-cortical projectionElectroencephalography and Clinical Neurophysiology, Vol. 32, No. 4Response of the optic tectum to stimulation of the optic nerve in the teleost Eugerres plumieriBrain Research, Vol. 31, No. 1Type of response to steady illumination and level of neuronal dark discharge in the central visual pathwaysBrain Research, Vol. 16, No. 1The relationship of optic nerve fiber groups activated by electrical stimulation to the consequent central postsynaptic eventsExperimental Neurology, Vol. 24, No. 3Monosynaptic activation of pyramidal cells in area 18 by optic radiation fibersExperimental Neurology, Vol. 21, No. 4The inhibitory path from the lateral geniculate body to the optic cortex in the catExperimental Neurology, Vol. 21, No. 4The effect of retinal illumination and retinal blockade on synaptic transmission in the lateral geniculate nucleus of the catVision Research, Vol. 7, No. 5-6Distinct spike discharges in the evoked cortical response of the light adapted catVision Research, Vol. 7, No. 5-6Neural limitations of visual excitability VIII: Binocular convergence in cat geniculate and cortexVision Research, Vol. 6, No. 7-8Cortical and subcortical evoked responses to central stimuli during wakefulness and sleepElectroencephalography and Clinical Neurophysiology, Vol. 18, No. 2The tonic control of cortical responsiveness by inhibitory and facilitatory diffuse influencesElectroencephalography and Clinical Neurophysiology, Vol. 18, No. 1Responsiveness in the visual system during various phases of sleep and wakingExperimental Neurology, Vol. 11, No. 1Visual cortical responses evoked by stimulating lateral geniculate body and optic radiations in awake and sleeping catsExperimental Neurology, Vol. 9, No. 1Evoked potentials of rabbit visual cortex: relationship between a slow negative potential and excitability cycleElectroencephalography and Clinical Neurophysiology, Vol. 15, No. 3Electric potentials of retina and cortex of cats evoked by monocular and binocular photic stimulationVision Research, Vol. 1, No. 1-2Facilitation réticulaire des mécanismes visuels corticauxElectroencephalography and Clinical Neurophysiology, Vol. 12, No. 4Evoked responses of the cat's visual cortex to optic tract stimulation at temperatures between 39° and 15°CElectroencephalography and Clinical Neurophysiology, Vol. 12, No. 3 More from this issue > Volume 19Issue 2March 1956Pages 172-186 https://doi.org/10.1152/jn.1956.19.2.172PubMed13295839History Published online 1 March 1956 Published in print 1 March 1956 Metrics

Antidromic stimulation of optic nerve and photosensitivity of cat retina.

Antidromic stimulation of optic nerve and photosensitivity of cat retina.

NATURE OF POTENTIALS ASSOCIATED WITH SYNAPTIC TRANSMISSION IN LATERAL GENICULATE OF CAT

ArticlesNATURE OF POTENTIALS ASSOCIATED WITH SYNAPTIC TRANSMISSION IN LATERAL GENICULATE OF CATP. O. Bishop, and J. G. McLeodP. O. Bishop, and J. G. McLeodPublished Online:01 Jul 1954https://doi.org/10.1152/jn.1954.17.4.387MoreSectionsPDF (4 MB)Download PDF ToolsExport citationAdd to favoritesGet permissionsTrack citations ShareShare onFacebookTwitterLinkedInWeChat Previous Back to Top Next Download PDF FiguresReferencesRelatedInformation Cited ByPeter Orlebar Bishop. 14 June 1917—3 June 201228 March 2018 | Biographical Memoirs of Fellows of the Royal Society, Vol. 64Reduced conduction velocity of retinal Y-cell axons following early partial removal of their synaptic targetsBrain Research, Vol. 514, No. 1Time- and frequency-dependent effects of potassium channel blockers on large and medium diameter optic tract axonsBrain Research, Vol. 498, No. 2Synaptic delay in the lateral geniculate nucleus of the catBrain Research, Vol. 343, No. 2Oscillations of the spontaneous slow-wave sleep rhythm in lateral geniculate nucleus relay neurons of behaving catsNeuroscience, Vol. 14, No. 4Chapter 11 Receptive fields of cat ganglion cells: Classification and constructionProgress in Retinal Research, Vol. 2Enhancement of cortical evoked potentials by high atmospheric pressures of heliumBrain Research Bulletin, Vol. 7, No. 4Neurophysiological tracing of a projection from temporal retina to contralateral visual cortex of the catVision Research, Vol. 21, No. 11Transmission processes in the ventrobasal complex of rat during the sleep-waking cycleBrain Research Bulletin, Vol. 5, No. 5Parallel visual pathways: A reviewVision Research, Vol. 20, No. 7Is reticular facilitation of lateral geniculate transmission due to inhibition of maintained firing of I-cells?Experimental Neurology, Vol. 65, No. 3Increased transneuronal excitation of the cat lateral geniculate nucleus after acute deafferentationBrain Research, Vol. 158, No. 1Inhibitory and excitatory binocular convergence to visual cortical neurons of the catBrain Research, Vol. 159, No. 1The effects of isovolemic hemodilution and reinfusion of packed erythrocytes on somatosensory and visual evoked potentialsJournal of Surgical Research, Vol. 25, No. 6Are field potentials an appropriate method for demonstrating connections in the brain?Experimental Neurology, Vol. 60, No. 3Laryngeal Spasm: A Neurophysiologic Redefinition29 June 2016 | Annals of Otology, Rhinology & Laryngology, Vol. 86, No. 2Evidence of W-cell input to the cat's visual cortex via the C laminae of the lateral geniculate nucleusBrain Research, Vol. 92, No. 3Simultaneous recording of pre- and postsynaptic potentials during the degeneration of the optic tract fiber input to the lateral geniculate nucleus of catsBrain Research, Vol. 81, No. 3The effects of eye movement and dark-adaptation on transmission through the visual pathways of unrestrained catsBrain Research, Vol. 77, No. 2Evoked potentials of the central visual system during and after hypoxia in catsElectroencephalography and Clinical Neurophysiology, Vol. 36Attempts to reverse the effects of disuse in the lateral geniculate nucleus of the catBrain Research, Vol. 62, No. 1Analysis of field response in optic tectum of the pigeonBrain Research, Vol. 54Cholinergic modulation of single lateral geniculate neurons in the catNeuropharmacology, Vol. 11, No. 2Attentive arousal and excitability of lateral geniculate body in free behaving catsVision Research, Vol. 11, No. 11The effect of some cholinomimetic drugs on presynaptic inhibition in the lateral geniculate nucleusNeuropharmacology, Vol. 10, No. 1Conduction velocity of optic nerve fibers innervating lateral geniculate body and superior colliculus in the ratExperimental Neurology, Vol. 25, No. 3Brachio-rubral and rubro-brachial activity in the catBrain Research, Vol. 15, No. 1The relationship of optic nerve fiber groups activated by electrical stimulation to the consequent central postsynaptic eventsExperimental Neurology, Vol. 24, No. 3Reticular facilitation of visually evoked responses by optic tract stimulation before and after enucleationExperimental Neurology, Vol. 22, No. 4Field potentials in the cat medial superior olivary nucleusExperimental Neurology, Vol. 20, No. 1Synaptic responsiveness in the lateral geniculate nucleus of the alert catVision Research, Vol. 7, No. 5-6Unitary analysis of retino-geniculate response time in ratsVision Research, Vol. 7, No. 3-4Influence du cortex visuel sur l'activitéévoquée dans les voies optiques sous-corticalesElectroencephalography and Clinical Neurophysiology, Vol. 20, No. 5Responsiveness of cat lateral geniculate at pre- and postsynaptic levels during natural sleepPhysiology & Behavior, Vol. 1, No. 1Neurophysiological effects of electrical anesthesiaExperimental Neurology, Vol. 13, No. 2Factors influencing potentials in normal and cretinous ratsElectroencephalography and Clinical Neurophysiology, Vol. 17, No. 3Electrical activity of lateral geniculate nucleus and optic tract of the ratVision Research, Vol. 4, No. 5-6Synaptic transfer in the lateral geniculate nucleus of catsExperimental Neurology, Vol. 9, No. 2Evidence supporting cholinergic transmission at the lateral geniculate body of the catInternational Journal of Neuropharmacology, Vol. 2, No. 3-4Cortical control and callosal mechanisms in the visual system of catElectroencephalography and Clinical Neurophysiology, Vol. 13, No. 4Effects of corticipetal and corticifugal impulses upon single elements of the dorsolateral geniculate nucleusExperimental Neurology, Vol. 2, No. 5Repetitive stimulation of optic nerve and lateral geniculate synapsesExperimental Neurology, Vol. 1, No. 6Lysergic acid diethylamide block of lateral geniculate synapses and relief by repetitive stimulationExperimental Neurology, Vol. 1, No. 6 More from this issue > Volume 17Issue 4July 1954Pages 387-414 https://doi.org/10.1152/jn.1954.17.4.387PubMed13175055History Published online 1 July 1954 Published in print 1 July 1954 Metrics

Synaptic transmission; an analysis of the electrical activity of the lateral geniculate nucleus in the cat after optic nerve stimulation.

The morphology of the optic nerve, the optic tract and the region of the dorsal nucleus of the ; lateral geniculate body (L. G. D.) in the cat is discussed from the point of view of the interpretation of electrical records obtained by means of microelectrodes inserted into them. The L. G. D. offers a very favourable morphological situation for studying the electrical correlates of synaptic transmission. All the fibres in the cat’s optic nerve are myelinated. By stimulating the nerve electrically .at its exit from the eyeball and adjusting the stimulus strength it may be arranged that of the two groups of fibres in the nerve, only those of larger diameter make a significant contribution to the records obtained from the contralateral geniculate. In this paper only large fibre 1 synaptic activity has been investigated. The conduction velocities of the bulk of the fibres in the two groups are 39 and 16 m/s respectively. The large-fibre impulse reaches the L. G. D. at about 0.9 ms after the stimulus artifact. It is concluded that the impulse is propagated to the extreme tip of the axon terminals. The synaptic delay averages 0.4 ms. The post-synaptic activity within the L. G. D. consists of a slow negative potential similar to the synaptic potential of Brooks &amp; Eccles (1947) and a propagated axonal spike. A positive potential similar in time course to the negative synaptic potential is recorded from the proximal portion of the optic radiation. The negative synaptic potential has a rise time of 0.3 to 0.6 ms, a half-time of 2.0 ms and falls to a low value after 5 ms. It is concluded that the presence of a positive synaptic potential indicates that the proximal portions of the axons are acting as sources of current for sinks in the region of the dendrites and cell bodies. It is suggested that the flows of current associated with the synaptic potential lead to the generation of the post-synaptic propagated spike in the region of the proximal portion of the axon. Conduction along dendrites probably does not occur in the L. G. D. The post-synaptic spike can be followed up the optic radiation towards the striate cortex. The duration of the radiation spike is significantly longer than that of the tract spike.

The intracortical excitability cycle following stimulation of the optic pathway of the cat

Like many neurones of the central nervous system, those of the optic cortex of the cat exhibit a brief phase of facilitation, followed by a more prolonged phase of depression, as tested by a shock to the optic radiation following a conditioning shock. Recovery toward normal occurs gradually, and is complete in about 200 msec. The negative phase of the specific response returns only much later than the preceding portions of the response. This cortical depression is not complete, and varies in intensity in different preparations treated similarly. A weak first shock depresses the response to a second to some degree, and as the first shock is made stronger this effect is greater, in some cases to complete occlusion of the second response. The depression is accompanied by a surface-negative swing of the baseline. A more severe depression occurs in the dorsal nucleus of the lateral geniculate body, as previously described by Marshall. Its recovery of responsiveness is slower than is that of the cortex. Thus to optic nerve stimulation the cortical activity is affected by two conditions of depression operating serially. The depressive effect at the geniculate can be recognized in responses from the cortex in terms of the amplitude of the first spike representing responses of radiation axons. Two shocks, the second within the facilitatory period of the first, can break through the depression left by a previous response, when neither can do so alone. Similarly two such shocks may cause a larger single response than can any one stimulus. From these superimposed effects of facilitation and depression exhibited by arbitrary volley responses, certain speculations are offered as to the normal manner of cortical functioning.