scholarly journals When the ostrich-algorithm fails: Blanking method affects spike train statistics

2017 ◽  
Author(s):  
Soheil Mottaghi ◽  
Kevin Joseph ◽  
Olaf Christ ◽  
Thomas J. Feuerstein ◽  
Ulrich G. Hofmann
Keyword(s):  
Electrical Stimulation ◽  
Spike Train ◽  
Action Potentials ◽  
Spike Rate ◽  
Neuronal Tissue ◽  
Electrophysiological Recordings ◽  
Frequency Of Stimulation ◽  
Theoretical Standpoint

1.AbstractElectrophysiological recordings of neuronal tissue face particular challenges when attempted during electrical stimulation, both in vivo and in vitro. Electrical stimulation may produce undesired electronic artifacts and thus render the recorded signal only partially useful. A commonly used remedy for these artifacts is to temporarily ground the input during the stimulation pulses. In the following study, we quantify the effects of this method on the spike train count, which is called "blanking". Starting a from theoretical standpoint, we deduce a loss of countable action potentials, depending on: width of the blanking window, Frequency of stimulation and neuronal activity. Calculations are corroborated by actual high SNR single cell recordings. We have to state, for therapeutically relevant frequencies of 130 Hz and realistic blanking windows of 2 ms, up to 27% of actual existing spikes are lost. We strongly advice careful and controlled use of blanking circuits when spike rate quantification is attempted.

Peripheral neural input to neurons of the stellate ganglion in dog

1982 ◽  
Vol 242 (3) ◽  
pp. R237-R243
Author(s):  
Z. J. Bosnjak ◽  
J. L. Seagard ◽  
J. P. Kampine
Keyword(s):  
Electrical Stimulation ◽  
Action Potentials ◽  
Stellate Ganglion ◽  
Afferent Input ◽  
In Vivo Studies ◽  
Organ Bath ◽  
Efferent Nerve ◽  
Stimulation Of

In vitro and in vivo studies were conducted on the stellate ganglion (SG) of the dog by recording action potentials from its nerves and its neurons. For in vitro preparations, the SG and its nerve trunks were dissected from the animal and secured in an organ bath. Peripheral input to the SG was produced by electrical stimulation of the ventral ansa subclavia (VA), dorsal ansa subclavia (DA), and stellate cardiac nerve (SC) in 15 ganglion preparations studied in vitro. Electrical stimulation of the VA elicited action potentials recorded at the DA. This conducting pathway did not involve direct anatomic continuity, since the evoked potentials were blocked by injection of hexamethonium chloride into the SG. Most neurons in the SG received synaptic input from fibers of both central and peripheral origin. In 12 in vivo preparations, all nerves to the SG except the VA were cut. When peripheral sympathetic afferent input to the SG was increased, some of the postganglionic fibers of the dissected DA exhibited an increase in efferent nerve discharge. This response was also blocked by hexamethonium chloride. These results indicate that some of the functions of the SG might be independent of the central nervous system.

scholarly journals A predictive in vitro risk assessment platform for pro-arrhythmic toxicity using human 3D cardiac microtissues

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Celinda M. Kofron ◽  
Tae Yun Kim ◽  
Fabiola Munarin ◽  
Arvin H. Soepriatna ◽  
Rajeev J. Kant ◽  
...  
Keyword(s):  
Risk Assessment ◽  
Action Potentials ◽  
Induced Pluripotent Stem Cell ◽  
Human Action ◽  
Environmental Toxicants ◽  
Pharmaceutical Drugs ◽  
Industrial Chemicals ◽  
Endocrine Disrupting Chemical

AbstractCardiotoxicity of pharmaceutical drugs, industrial chemicals, and environmental toxicants can be severe, even life threatening, which necessitates a thorough evaluation of the human response to chemical compounds. Predicting risks for arrhythmia and sudden cardiac death accurately is critical for defining safety profiles. Currently available approaches have limitations including a focus on single select ion channels, the use of non-human species in vitro and in vivo, and limited direct physiological translation. We have advanced the robustness and reproducibility of in vitro platforms for assessing pro-arrhythmic cardiotoxicity using human induced pluripotent stem cell-derived cardiomyocytes and human cardiac fibroblasts in 3-dimensional microtissues. Using automated algorithms and statistical analyses of eight comprehensive evaluation metrics of cardiac action potentials, we demonstrate that tissue-engineered human cardiac microtissues respond appropriately to physiological stimuli and effectively differentiate between high-risk and low-risk compounds exhibiting blockade of the hERG channel (E4031 and ranolazine, respectively). Further, we show that the environmental endocrine disrupting chemical bisphenol-A (BPA) causes acute and sensitive disruption of human action potentials in the nanomolar range. Thus, this novel human 3D in vitro pro-arrhythmic risk assessment platform addresses critical needs in cardiotoxicity testing for both environmental and pharmaceutical compounds and can be leveraged to establish safe human exposure levels.

scholarly journals Depolarization and electrical stimulation enhance in vitro and in vivo sensory axon growth after spinal cord injury

2018 ◽  
Vol 300 ◽  
pp. 247-258 ◽  
Author(s):  
Ioana Goganau ◽  
Beatrice Sandner ◽  
Norbert Weidner ◽  
Karim Fouad ◽  
Armin Blesch
Keyword(s):  
Spinal Cord ◽  
Spinal Cord Injury ◽  
Electrical Stimulation ◽  
Axon Growth ◽  
Sensory Axon ◽  
Cord Injury

Ex Vivo Brain Preparation to Analyze Vocal Pathways of Xenopus Frogs

2021 ◽  
Vol 2021 (9) ◽  
pp. pdb.prot106872
Author(s):  
Ayako Yamaguchi
Keyword(s):  
Neural Activity ◽  
Ex Vivo ◽  
Neural Circuitry ◽  
Neural Basis ◽  
Vocal Production ◽  
Basic Principles ◽  
Electrophysiological Recordings ◽  
The Brain

Understanding the neural basis of behavior is a challenging task for technical reasons. Most methods of recording neural activity require animals to be immobilized, but neural activity associated with most behavior cannot be recorded from an anesthetized, immobilized animal. Using amphibians, however, there has been some success in developing in vitro brain preparations that can be used for electrophysiological and anatomical studies. Here, we describe an ex vivo frog brain preparation from which fictive vocalizations (the neural activity that would have produced vocalizations had the brain been attached to the muscle) can be elicited repeatedly. When serotonin is applied to the isolated brains of male and female African clawed frogs, Xenopus laevis, laryngeal nerve activity that is a facsimile of those that underlie sex-specific vocalizations in vivo can be readily recorded. Recently, this preparation was successfully used in other species within the genus including Xenopus tropicalis and Xenopus victorianus. This preparation allows a variety of techniques to be applied including extracellular and intracellular electrophysiological recordings and calcium imaging during vocal production, surgical and pharmacological manipulation of neurons to evaluate their impact on motor output, and tract tracing of the neural circuitry. Thus, the preparation is a powerful tool with which to understand the basic principles that govern the production of coherent and robust motor programs in vertebrates.

Peripheral neural input to neurons of the middle cervical ganglion in the cat

1984 ◽  
Vol 246 (3) ◽  
pp. R354-R358
Author(s):  
Z. J. Bosnjak ◽  
J. P. Kampine
Keyword(s):  
Electrical Stimulation ◽  
Synaptic Input ◽  
Action Potentials ◽  
Efferent Nerve ◽  
Neural Input ◽  
Central Origin ◽  
Cervical Ganglion ◽  
Intracellular Action ◽  
Peripheral Origin

In vitro studies were conducted on the middle cervical ganglion (MCG) of the cat by recording intracellular action potentials from its neurons. The purpose of this study was to examine the possibility of a peripheral synaptic input to the MCG. Preganglionic electrical stimulation, via the ventral ansa (VA) and dorsal ansa (DA) subclavia, and post-ganglionic electrical stimulation, via the ventrolateral cardiac nerve (VCN), evoked graded synaptic responses that led to the discharge of one or more action potentials in the 14 ganglia studied. The conduction velocity of these pathways ranged from 0.4 to 0.9 m/s. Ten percent of the cells impaled were inexcitable, even with direct intracellular depolarizing current, whereas 80% of the neurons studied received a synaptic input from fibers of both central and peripheral origin. In addition, subthreshold synaptic inputs from peripheral and central origin sum to discharge the cell, suggesting an integration of neural inputs in the MCG. These responses were blocked by d-tubocurarine chloride. This evidence indicates that sympathetic efferent nerve activity can be modified by peripheral excitatory inputs and that these inputs may function as pathways for a peripheral reflex at the level of the MCG.

NO inhibits supraoptic oxytocin and vasopressin neurons via activation of GABAergic synaptic inputs

2001 ◽  
Vol 280 (6) ◽  
pp. R1815-R1822 ◽  
Author(s):  
Javier E. Stern ◽  
Mike Ludwig
Keyword(s):  
Neuronal Excitability ◽  
Cell Types ◽  
Synaptic Activity ◽  
No Donor ◽  
Whole Cell Patch Clamp ◽  
Electrophysiological Recordings ◽  
Neuronal Types ◽  
Vasopressin Neurons

To study modulatory actions of nitric oxide (NO) on GABAergic synaptic activity in hypothalamic magnocellular neurons in the supraoptic nucleus (SON), in vitro and in vivo electrophysiological recordings were obtained from identified oxytocin and vasopressin neurons. Whole cell patch-clamp recordings were obtained in vitro from immunochemically identified oxytocin and vasopressin neurons. GABAergic synaptic activity was assessed in vitro by measuring GABAA miniature inhibitory postsynaptic currents (mIPSCs). The NO donor and precursor sodium nitroprusside (SNP) and l-arginine, respectively, increased the frequency and amplitude of GABAA mIPSCs in both cell types ( P ≤ 0.001). Retrodialysis of SNP (50 mM) onto the SON in vivo inhibited the activity of both neuronal types ( P ≤ 0.002), an effect that was reduced by retrodialysis of the GABAA-receptor antagonist bicuculline (2 mM, P≤ 0.001). Neurons activated by intravenous infusion of 2 M NaCl were still strongly inhibited by SNP. These results suggest that NO inhibition of neuronal excitability in oxytocin and vasopressin neurons involves pre- and postsynaptic potentiation of GABAergic synaptic activity in the SON.

Synaptic and intrinsic responses of medical entorhinal cortical cells in normal and magnesium-free medium in vitro

1988 ◽  
Vol 59 (5) ◽  
pp. 1476-1496 ◽  
Author(s):  
R. S. Jones ◽  
U. Heinemann
Keyword(s):  
Entorhinal Cortex ◽  
Action Potentials ◽  
Membrane Conductance ◽  
Nmda Receptor Antagonist ◽  
Field Potentials ◽  
Cortical Cells ◽  
Medial Entorhinal Cortex ◽  
Membrane Hyperpolarization

1. Extracellular recordings were made from slices of hippocampus plus parahippocampal regions maintained in vitro. Field potentials, recorded in the entorhinal cortex after stimulation in the subiculum, resembled those observed in vivo. 2. Washout of magnesium from the slices resulted in paroxysmal events which resembled those occurring during sustained seizures in vivo. These events were greatest in amplitude and duration in layers IV/V of the medial entorhinal cortex and could occur both spontaneously and in response to subicular stimulation. Spontaneous seizure-like events were not prevented by severing the connections between the hippocampus and entorhinal cortex, but much smaller and shorter events occurring in the dentate gyrus were stopped by this manipulation. Both spontaneous and evoked paroxysmal events were blocked by perfusion with the N-methyl-D-aspartate (NMDA) receptor antagonist, DL-2-amino-5-phosphonovalerate (2-AP5). 3. Neurons in layers IV/V were characterized by intracellular recording. Injection of depolarizing current in most cells evoked a train of nondecrementing action potentials with only weak spike frequency accommodation and little or no posttrain after hyperpolarization. 4. A small number of cells displayed burst response when depolarized by positive current. The burst consisted of a slow depolarization with superimposed action potentials which decreased in amplitude and increased in duration during the discharge. The burst was terminated by a strong after hyperpolarization and thereafter, during prolonged current pulses a train of nondecrementing spikes occurred. The burst response remained if the cell was held at hyperpolarized levels but was inactivated by holding the cell at a depolarized level. 5. Depolarizing synaptic potentials could be evoked by stimulation in the subiculum. A delayed and prolonged depolarization clearly decremented with membrane hyperpolarization and, occasionally, increased with depolarization. 6. Washout of magnesium from the slices resulted in an enhancement of the late depolarization and a reversal of its voltage dependence. Eventually a single shock to the subiculum evoked a large all-or-none paroxysmal depolarization associated with a massive increase in membrane conductance. Similar events occurred spontaneously in all cells tested. The paroxysmal depolarizations, both spontaneous and evoked, were rapidly blocked by 2-AP5. 7. It is concluded that medial entorhinal cortical cells possess several intrinsic and synaptic properties which confer an extreme susceptibility to generation of sustained seizure activity.(ABSTRACT TRUNCATED AT 400 WORDS)

Lysophosphoglycerides in ischemic myocardium effluents and potentiation of their arrhythmogenic effects

1981 ◽  
Vol 241 (5) ◽  
pp. H700-H707 ◽  
Author(s):  
D. W. Snyder ◽  
W. A. Crafford ◽  
J. L. Glashow ◽  
D. Rankin ◽  
B. E. Sobel ◽  
...  
Keyword(s):  
Action Potentials ◽  
Extracellular Fluid ◽  
Ischemic Myocardium ◽  
Resting Membrane Potential ◽  
Phase 0 ◽  
Control Plasma ◽  
Maximum Rate Of Rise ◽  
Arrhythmogenic Effects

Lysophosphoglycerides accumulate in ischemic myocardium. To determine whether lysophosphatidylcholine (LPC) concentrations increase in extracellular fluid and may be arrhythmogenic, the anterior descending coronary artery of the open-chest cat (n = 12) was perfused with a Krebs-albumin solution after 10 min of ischemia and the effluent assayed for LPC. A twofold increase in LPC (0.097 +/- 0.02 to 0.170 +/- 0.03 mM) was observed. Microelectrode intracellular recordings from from normal feline endocardium at pH 7.4 in vitro revealed little change in action potentials when superfused with feline plasma despite augmented LPC to twice normal levels (0.74 mM). However, at pH 6.7, marked changes were elicited by LPC-enriched plasma including diminished resting membrane potential (-96 +/- 1 to -35 +/- 7 mV), amplitude (102 +/- 3 to 36 +/- 8 mV), maximum rate of rise (Vmax) of phase 0 (178 +/- 24 to 26 +/- 11 V/s), and conduction velocity with fractionation of the action potential. Acidified control plasma decreased only Vmax (from 161 to 57 V/s). Thus LPC increases twofold in effluents from cat myocardium in vivo after 10 min of ischemia and, coupled with ischemia-induced acidosis, is sufficient to induce marked electrophysiological derangements in vitro.

41 STUDY ON THE ESTABLISHMENT OF SOMATIC CELL NUCLEAR TRANSFER USING IN VIVO-MATURED OOCYTES IN DOGS

2006 ◽  
Vol 18 (2) ◽  
pp. 129 ◽  
Author(s):  
G. Jang ◽  
M. Kim ◽  
H. J. Oh ◽  
F. Y. Heru ◽  
M. S. Hossein ◽  
...  
Keyword(s):  
Electrical Stimulation ◽  
Somatic Cell Nuclear Transfer ◽  
Nuclear Transfer ◽  
Chemical Activation ◽  
Developmental Competence ◽  
Perivitelline Space ◽  
Parthenogenetic Activation ◽  
Vaginal Cytology

The present study was performed to collect in vivo matured canine oocytes for somatic cell nuclear transfer (SCNT) and to investigate the developmental competence of canine parthenogenetic and SCNT embryos as the preliminary research for producing cloned dog. The day of ovulation as described by Hase et al. (2000 J. Vet. Med. Sci. 62, 243-248) was determined by serum progesterone levels and at that time vaginal cytology was performed to assess the cornified index. In vivo-matured oocytes were recovered by retrograde flushing of the oviducts at around 48 h (n = 20) or 72 h (n = 25) after the estimated time of ovulation. Overall size of each oocyte, as well as ooplasmic diameter, zona pellucida thickness, and perivitelline space width, was determined after removing the cumulus cells by pipetting (Exp. 1). To determine activation protocols, two treatments, (1) chemical activation (10 �M Ca ionophore for 4 min, followed by incubation for 4 h with 1.9 mM 6-dimethylaminopurine) and (2) electrical stimulation (3.1?3.4 kV/cm in 0.25M mannitol solution), were evaluated to induce parthenogenetic activation of oocytes (Exp. 2). Donor cells were obtained from the primary cell culture of a canine ear skin biopsy, and SCNT was performed according to our laboratory procedures (Jang et al. 2004 Theriogenology 62, 512-521). Three voltages (1.7?2.0 kV/cm, 2.1-2.4 kV/cm, and 3.1-3.4 kV/cm) were tested for fusion. The fused couplets were subjected to chemical or electrical stimulation as in parthenogenetic activation and in vitro developmental competence was monitored (Exp. 3). As a result, more in vivo-matured canine oocytes were obtained at 72 h (92%) than at 48 h (15%) after ovulation; the 72-h occytes had progesterone concentrations of 4-8 ng/mL and a cornified index (vaginal cytology) of 83.34. The average number of oocytes recovered was 12 and sizes of ooplasmic diameter, cytoplasm, zona pellucida, and perivitelline space in in vivo canine-matured oocytes (n = 120) were 178.8 � 9.3 �m, 125.0 � 8.2 �m, 21.7 � 3.7 �m, and 12.7 � 3.5 �m, respectively. Parthenogenetically activated oocytes developed to the 16-cell and morula stages, but failed to develop to the blastocyst stage. Among the three voltages, in the highest voltage (75.2%) the number of fused couplets was increased compared to either of the other voltages (33.3% and 44.0%). Cleavage rates (60.9% vs. 58.0%) of cloned embryos were not significantly affected by method of activation. In terms of in vitro developmental competence, cloned embryos developed to the 16-cell or morula stage in vitro after electrical or chemical activation, respectively. In conclusion, in the present study we demonstrated that measurement of progesterone levels, in combination with evaluation of vaginal cytology, can be used to determine the estimated time of ovulation in bitches. In addition, we determined fusion/activation protocols that resulted in in vitro development of a portion of parthenogenetically activated and cloned embryos to the 16-cell and morula stages. This study was supported by grants from the Biogreen 21-1000520030100000.

scholarly journals Photoacoustic effect invokes auditory response in infrared neuron stimulation

2019 ◽  
Vol 12 (01) ◽  
pp. 1850040
Author(s):  
Muqun Yang ◽  
Tian Guan ◽  
Yonghong He
Keyword(s):  
Fluorescence Microscopy ◽  
Guinea Pig ◽  
Action Potentials ◽  
Photoacoustic Effect ◽  
In Vivo Experiments ◽  
Compound Action Potentials ◽  
Auditory Response ◽  
Compound Action

Infrared neuron stimulation is regarded as an innovative approach for stimulating cochleae in animals while the exact mechanism still remains unknown. In this paper, we studied compound action potentials of guinea pig cochleae with chronic or acute deafness. We recorded optical compound action potentials and analyzed stretched cochlear preparations by fluorescence microscopy. Photoacoustic signals were measured by hydrophone and microphone, respectively. In our experiment, we observed a switch response effect in vitro and in vivo experiments. Therefore, we proposed photoacoustic effect could invoke auditory response in infrared neuron stimulation.

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