scholarly journals Modeling subcortical white matter stimulation

2019 ◽  
Author(s):  
Melissa Dali ◽  
Jennifer S. Goldman ◽  
Olivier Pantz ◽  
Alain Destexhe ◽  
Emmanuel Mandonnet
Keyword(s):  
Electrical Stimulation ◽  
Action Potentials ◽  
Subcortical White Matter ◽  
Bipolar Electrode ◽  
Individual Subject ◽  
Tissue Conductivity ◽  
Bipolar Electrodes ◽  
Stimulation Parameters ◽  
Monopolar Stimulation ◽  
Activation Depth

AbstractObjectiveIntracranial electrical stimulation of subcortical axonal tracts is particularly useful during brain surgery, where mapping helps identify and excise dysfunctional tissue while avoiding damage to functional structures. Stimulation parameters are generally set empirically and consequences for the spatial recruitment of axons within subcortical tracts are not well identified.ApproachComputational modeling is employed to study the effects of stimulation parameters on the recruitment of axons: monophasic versus biphasic stimuli induced with monopolar versus bipolar electrodes, oriented orthogonal or parallel to the tract, for isotropic and anisotropic tracts.Main resultsThe area and depth of axonal activation strongly depend on tissue conductivity and electrode parameters. The largest activation area results from biphasic stimulation with bipolar electrodes oriented orthogonal to axonal fasciculi, for anisotropic and especially isotropic tracts. For anisotropic tracts, the maximal activation depth is similar regardless of whether a monopolar or bipolar electrode is employed. For isotropic tracts, bipolar parallel and monopolar stimulation activate axons deeper than orthogonal bipolar stimulation. Attention is warranted during monophasic stimulation: a blockade of action potentials immediately under cathodes and a propagation of action potentials under anodes are found.SignificanceConsidering the spatial patterns of blockade and activation present during monophasic stimulation with both monopolar and bipolar electrodes, biphasic stimulation is recommended to explore subcortical axon responses during intraoperative mapping. Finally, the precise effect of electrical stimulation depends on conductivity profiles of tracts, and as such, should be explicitly considered for each individual subject and tract undergoing intracranial mapping.

Tetrodotoxin-resistant release of ATP from superfused rabbit detrusor muscle during electrical field stimulation in the presence of luciferin–luciferase

1984 ◽  
Vol 62 (1) ◽  
pp. 153-156 ◽  
Author(s):  
Archana Chaudhry ◽  
John W. Downie ◽  
Thomas D. White
Keyword(s):  
Action Potentials ◽  
Electrical Field Stimulation ◽  
Detrusor Muscle ◽  
Electrical Field ◽  
Stimulation Parameters ◽  
Rabbit Bladder ◽  
Firefly Luciferin ◽  
Rabbit Urinary Bladder ◽  
Stimulation Of

The present study was carried out to assess the possible role of ATP in the noncholinergic, nonadrenergic transmission in the rabbit urinary bladder. When rabbit detrusor muscle strips were superfused with medium containing firefly luciferin–luciferase and stimulated transmurally at low stimulation parameters, tetrodotoxin-sensitive contractions were obtained but no release of ATP could be detected. However, at somewhat higher stimulation parameters, release of ATP was observed. This release of ATP was not diminished by tetrodotoxin indicating that ATP was not likely released as a result of propagated action potentials in nerves. Because contractions persisted in the presence of tetrodotoxin, it is possible that the ATP might have been released as a result of direct electrical stimulation of the muscle. These results do not support the idea that ATP is released as a neurotransmitter in the rabbit bladder.

Electronmicroscopic and electrophysiological studies of the teat branch of the XIII thoracic nerve: relationship with lactation in the rat

1988 ◽  
Vol 118 (3) ◽  
pp. 471-483 ◽  
Author(s):  
L. M. Voloschin ◽  
E. Décima ◽  
J. H. Tramezzani
Keyword(s):  
Electrical Stimulation ◽  
Conduction Velocity ◽  
Action Potentials ◽  
Silent Period ◽  
High Amplitude ◽  
Milk Ejection ◽  
Nerve Activity ◽  
Thoracic Nerve ◽  
Myelinated Fibres ◽  
Stimulation Of

ABSTRACT Electrical stimulation of the XIII thoracic nerve (the 'mammary nerve') causes milk ejection and the release of prolactin and other hormones. We have analysed the route of the suckling stimulus at the level of different subgroups of fibres of the teat branch of the XIII thoracic nerve (TBTN), which innervates the nipple and surrounding skin, and assessed the micromorphology of the TBTN in relation to lactation. There were 844 ± 63 and 868 ± 141 (s.e.m.) nerve fibres in the TBTN (85% non-myelinated) in virgin and lactating rats respectively. Non-myelinated fibres were enlarged in lactating rats; the modal value being 0·3–0·4 μm2 for virgin and 0·4–0·5 μm2 for lactating rats (P > 0·001; Kolmogorov–Smirnov test). The modal value for myelinated fibres was 3–6 μm2 in both groups. The compound action potential of the TBTN in response to electrical stimulation showed two early volleys produced by the Aα- and Aδ-subgroups of myelinated fibres (conduction velocity rate of 60 and 14 m/s respectively), and a late third volley originated in non-myelinated fibres ('C') group; conduction velocity rate 1·4 m/s). Before milk ejection the suckling pups caused 'double bursts' of fibre activity in the Aδ fibres of the TBTN. Each 'double burst' consisted of low amplitude action potentials and comprised two multiple discharges (33–37 ms each) separated by a silent period of around 35 ms. The 'double bursts' occurred at a frequency of 3–4/s, were triggered by the stimulation of the nipple and were related to fast cheek movements visible only by watching the pups closely. In contrast, the Aα fibres of the TBTN showed brief bursts of high amplitude potentials before milk ejection. These were triggered by the stimulation of cutaneous receptors during gross slow sucking motions of the pup (jaw movements). Immediately before the triggering of milk ejection the mother was always asleep and a low nerve activity was recorded in the TBTN at this time. When reflex milk ejection occurred, the mother woke and a brisk increase in nerve activity was detected; this decreased when milk ejection was accomplished. In conscious rats the double-burst type of discharges in Aδ fibres was not observed, possibly because this activity cannot be detected by the recording methods currently employed in conscious animals. During milk ejection, action potentials of high amplitude were conveyed in the Aα fibres of the TBTN. During the treading time of the stretch reaction (SR), a brisk increase in activity occurred in larger fibres; during the stretching periods of the SR a burst-type discharge was again observed in slow-conducting afferents; when the pups changed nipple an abrupt increase in activity occurred in larger fibres. In summary, the non-myelinated fibres of the TBTN are increased in diameter during lactation, and the pattern of suckling-evoked nerve activity in myelinated fibres showed that (a) the double burst of Aδ fibres, produced by individual sucks before milk ejection, could be one of the conditions required for the triggering of the reflex, and (b) the nerve activity displayed during milk-ejection action may result, at least in part, from 'non-specific' stimulation of cutaneous receptors. J. Endocr. (1988) 118, 471–483

Abstract P498: Polycystin-1 Regulates Excitation-contraction Coupling In Atrial Cardiomyocytes

2021 ◽  
Vol 129 (Suppl_1) ◽  
Author(s):  
Troy Hendrickson ◽  
William Perez ◽  
Vincent Provasek ◽  
Francisco J Altamirano
Keyword(s):  
Electrical Stimulation ◽  
Action Potentials ◽  
Primary Cilia ◽  
Calcium Influx ◽  
Calcium Transient ◽  
Calcium Handling ◽  
Excitation Contraction Coupling ◽  
Contraction Coupling ◽  
Atrial Cardiomyocytes ◽  
Atrial Excitation

Patients with Autosomal Dominant Polycystic Kidney disease (ADPKD) have multiple cardiovascular manifestations, including increased susceptibility to arrhythmias. Mutations in polycystin-1 (PC1) encoding gene accounts for 85% cases of ADPKD, whereas mutations in polycystin-2 (PC2) only accounts for 15%. In kidney cells, PC1 interacts with PC2 to form a protein complex at the primary cilia to regulate calcium influx via PC2. However, cardiomyocytes are non-ciliated cells and the role of both PC1 and PC2 in atrial cardiomyocytes remains unknown. We have previously demonstrated that PC1 regulates action potentials and calcium handling to fine-tune ventricular cardiomyocyte contraction. Here, we hypothesize that PC1 regulates action potentials and calcium handling in atrial cardiomyocytes independent of PC2 actions. To test this hypothesis, we differentiated human induced pluripotent stem cells (iPSC) into atrial cardiomyocytes (iPSC-aCM) using previously published protocols. To determine the contribution of PC1/PC2 in atrial excitation-contraction coupling, protein expression was knocked down utilizing specific siRNA constructs, for each protein, or a universal control siRNA transfected using lipofectamine RNAiMAX. We measured action potentials using the potentiometric dye FluoVolt and intracellular calcium with Fura-2 AM or Fluo-4. Changes in fluorescence were monitored using a multiwavelength IonOptix system. iPSC-aCM were paced at 2 Hz to synchronize the beating pattern using field electrical stimulation. Our data shows that PC1 ablation significantly decreased action potential duration at 50% and 80% of repolarization, by 24% and 23%, respectively. Moreover, we observed that PC1 knockdown significantly reduced calcium transient amplitude elicited by field electrical stimulation without changes in calcium transient decay. Interestingly, PC2 knockdown did not modify calcium transients in atrial cardiomyocytes (iPSC-aCM). Our data suggest that PC1 regulates atrial excitation-contraction coupling independent of PC2 actions. This study warrants further investigation into atrial dysfunction in ADPKD patients with PC1 mutations.

Monopolar and bipolar stimulation of the brain

1962 ◽  
Vol 203 (2) ◽  
pp. 371-373 ◽  
Author(s):  
Paul Stark ◽  
Giovanni Fazio ◽  
Eugene S. Boyd
Keyword(s):  
Current Density ◽  
Bipolar Electrode ◽  
Wire Electrode ◽  
Bipolar Stimulation ◽  
Monopolar Stimulation ◽  
Stimulation Experiments ◽  
Self Stimulation ◽  
The Brain ◽  
Rate Of Response ◽  
Stimulation Of

Intracranial self-stimulation experiments in the dog using a two-wire electrode, with each wire used as a monopolar electrode and the combination as a bipolar electrode, show that monopolar stimulation may produce either a higher or a lower rate of response than that produced by bipolar stimulation. A theoretical consideration of the changes in current density around the electrode when it is changed from a monopolar to a bipolar electrode shows that such differences are to be expected. The exact location of the structure being stimulated with reference to the two electrode tips will determine whether the structure is subjected to a higher current density on monopolar or on bipolar stimulation.

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.

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