Evidence for a synaptically mediated decrease in conductance in a crustacean myocardium

1976 ◽  
Vol 65 (1) ◽  
pp. 117-129
Author(s):  
J. C. Delaleu
Keyword(s):  
Electrical Stimulation ◽  
Heart Muscle ◽  
Membrane Resistance ◽  
Inward Current ◽  
Partial Restoration ◽  
Inhibitory Processes ◽  
Myocardial Membrane ◽  
Composite Nature ◽  
Inhibitory Regulation ◽  
Stimulation Of

1. In the neurogenic heart of the isopod Porcellio dilatatus, electrical stimulation of the cardio-regulatory nerves at rates greater than 20–25 pulses/s elicited inhibitory junctional potentials (IJPs) in the myocardium. Its cessation was followed by a long lasting hyperpolarization of myocardial membrane (post-stimulus hyperpolarization = PSH). 2. During the PSH the membrane resistance of the heart muscle increased. The PSH was enhanced by myocardium hyperpolarization, decreased by depolarization and reversed around −50 mV. 3. Picrotoxin inhibited the summated IJPs elicited by the stimulation and thus caused the membrane to maximally hyperpolarize during inhibitory train, thus suggesting a composite nature of the inhibitory processes. 4. The PSH was reversibly reduced in K+-free saline or in ouabain containing saline but partial restoration was obtained by injection of inward current to the myocardium. 5. The PSH was abolished in lithium saline and reduced in Na+-deficient (choline) solution. Cl-deficient solution that markedly affected the summated IJPs shortly after its introduction did not affect the PSH. 6. It is proposed that the PSH results from a decrease in conductance, presumably to both Na+ and K+. The implication of such a mechanism as a component of the inhibitory regulation of this crustacean heart is discussed.

Electrical stimulation of retinal neurons in epiretinal and subretinal configuration using a multicapacitor array

2012 ◽  
Vol 107 (10) ◽  
pp. 2742-2755 ◽  
Author(s):  
Max Eickenscheidt ◽  
Martin Jenkner ◽  
Roland Thewes ◽  
Peter Fromherz ◽  
Günther Zeck
Keyword(s):  
Electrical Stimulation ◽  
Ganglion Cells ◽  
Ex Vivo ◽  
Biophysical Model ◽  
Retinal Neurons ◽  
Direct Stimulation ◽  
Tungsten Electrode ◽  
Partial Restoration ◽  
Low Amplitude ◽  
Stimulation Of

Electrical stimulation of retinal neurons offers the possibility of partial restoration of visual function. Challenges in neuroprosthetic applications are the long-term stability of the metal-based devices and the physiological activation of retinal circuitry. In this study, we demonstrate electrical stimulation of different classes of retinal neurons with a multicapacitor array. The array—insulated by an inert oxide—allows for safe stimulation with monophasic anodal or cathodal current pulses of low amplitude. Ex vivo rabbit retinas were interfaced in either epiretinal or subretinal configuration to the multicapacitor array. The evoked activity was recorded from ganglion cells that respond to light increments by an extracellular tungsten electrode. First, a monophasic epiretinal cathodal or a subretinal anodal current pulse evokes a complex burst of action potentials in ganglion cells. The first action potential occurs within 1 ms and is attributed to direct stimulation. Within the next milliseconds additional spikes are evoked through bipolar cell or photoreceptor depolarization, as confirmed by pharmacological blockers. Second, monophasic epiretinal anodal or subretinal cathodal currents elicit spikes in ganglion cells by hyperpolarization of photoreceptor terminals. These stimuli mimic the photoreceptor response to light increments. Third, the stimulation symmetry between current polarities (anodal/cathodal) and retina-array configuration (epi/sub) is confirmed in an experiment in which stimuli presented at different positions reveal the center-surround organization of the ganglion cell. A simple biophysical model that relies on voltage changes of cell terminals in the transretinal electric field above the stimulation capacitor explains our results. This study provides a comprehensive guide for efficient stimulation of different retinal neuronal classes with low-amplitude capacitive currents.

scholarly journals Electrical Stimulation of Artificial Heart Muscle

ASAIO Journal ◽  
2017 ◽  
Vol 63 (3) ◽  
pp. 333-341 ◽  
Author(s):  
Mohamed A. Mohamed ◽  
Jose F. Islas ◽  
Robert J. Schwartz ◽  
Ravi K. Birla
Keyword(s):  
Electrical Stimulation ◽  
Heart Muscle ◽  
Artificial Heart ◽  
Stimulation Of

scholarly journals Differential optogenetic excitation of the auditory midbrain in freely moving behaving mice

2021 ◽  
Author(s):  
Meike M. Rogalla ◽  
Adina Seibert ◽  
K Jannis Hildebrandt
Keyword(s):  
Electrical Stimulation ◽  
Surrounding Medium ◽  
Frequency Discrimination ◽  
Auditory Midbrain ◽  
Partial Restoration ◽  
Neuronal Ensembles ◽  
Sensory Pathway ◽  
Freely Moving ◽  
Differential Excitation ◽  
Stimulation Of

AbstractIn patients with severe sensory impairment due to compromised peripheral function, partial restoration can be achieved by implantation of sensory prostheses for the electrical stimulation of the central nervous system. However, these state of the art approaches suffer from the drawback of limited spectral resolution. Electrical field spread depends on the impedance of the surrounding medium, impeding spatially focused electrical stimulation in neural tissue. To overcome these technical limitations, optogenetic excitation could be applied in such prostheses to achieve enhanced resolution through precise and differential stimulation of nearby neuronal ensembles within the central sensory pathway. Previous experiments have provided a first proof for behavioral detectability of optogenetic excitation in the rodent auditory system. However, little is known about the generation of complex and behaviorally relevant sensory patterns involving differential excitation. In this study, we developed an optogenetic implant to excite two spatially separated points along the tonotopy of the murine central inferior colliculus (ICc). Using a newly-devised reward-based operant Go/No-Go paradigm for the evaluation of optogenetic excitation of the auditory midbrain in freely moving, behaving mice, we demonstrate that differential optogenetic excitation of a sub-cortical sensory pathway is possible and efficient. Here we demonstrate how animals which were previously trained in a frequency discrimination paradigm a) rapidly generalize between sound and optogenetic excitation, b) generally detect optogenetic excitation at two different neuronal ensembles, and c) discriminate between them. Our results demonstrate for the first time that optogenetic excitation at different points of the ICc tonotopy elicits a stable response behavior over time periods of several months. With this study, we provide the first proof of principle for sub-cortical differential stimulation of sensory systems using complex artificial cues in freely moving animals.

Recovery cycle of visual cortex of the awake and sleeping cat

1960 ◽  
Vol 199 (2) ◽  
pp. 373-376 ◽  
Author(s):  
Edward V. Evarts ◽  
T. Corwin Fleming ◽  
Peter R. Huttenlocher
Keyword(s):  
Electrical Stimulation ◽  
Visual Cortex ◽  
Cortical Response ◽  
Recovery Cycle ◽  
Implanted Electrodes ◽  
Inhibitory Processes ◽  
Test Response ◽  
Identical Test ◽  
Conditioning Stimuli ◽  
Stimulation Of

Cats with chronically implanted electrodes were employed in studies of the effects of sleep and waking on the recovery cycle of the cortical response to electrical stimulation of lateral geniculate radiations. Identical test and conditioning stimuli were delivered to the geniculate radiations at intervals of 3.2–1000 msec. At intervals between 16 and 200 msec., the subnormality of the test response was more marked during waking than during sleep. Amplitude of responses to single stimuli was greater during sleep than during waking. The results are discussed in relation to the hypothesis that there is an increase in the activity of inhibitory processes in the visual cortex during waking.

Ibotenic acid: its excitatory and possibly sedative actions in cerebral cortex

1981 ◽  
Vol 59 (9) ◽  
pp. 1025-1030 ◽  
Author(s):  
E. Puil
Keyword(s):  
Cerebral Cortex ◽  
Electrical Stimulation ◽  
Cortical Neurons ◽  
Ibotenic Acid ◽  
Membrane Resistance ◽  
Synaptic Activity ◽  
Repetitive Firing ◽  
Cortical Surface ◽  
Repeated Applications ◽  
Stimulation Of

A slowly developing excitation with afterdischarge is produced by microiontophoretic application of the racemate of ibotenic acid to pericruciate cortical neurons of cats which had been "decerebrated" by forebrain isolation during brief anesthesia. The extracellularly observed excitation tended to accumulate with repeated applications. In many instances the ibotenate excitation was blocked with local administrations of H2-receptor antagonists which also "antagonized" glutamate excitation. With intracellular recording, similar iontophoretic applications of ibotenate were observed to produce longlasting depolarizations and repetitive firing which was not maintained despite suprathreshoid depolarization. These actions were not accompanied by consistent changes in membrane resistance. A most striking feature of ibotenate action was to increase spontaneous synaptic activity and the amplitude of EPSP's evoked by electrical stimulation of the cortical surface or n. ventralis lateralis of the thalamus. These new data are strongly suggestive of presynaptic actions of ibotenate in the cerebral cortex although postsynaptic actions of this isoxazole presumably are also important to an understanding of how ibotenate produces its inebriating and hypnotic effects in animals and man.

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