X.H.T.W. is a W.M. Keck Foundation Distinguished Young Scholar in Medical Research, and is also supported by NIH/NHLBI grants R01-HL089598 and R01HL091947, and Muscular Dystrophy Association grant #69238. This work is also supported in part by the Fondation Leducq Alliance for CaMKII Signalling in Heart. N.L. is the recipient of the 2009-2010 Michel Mirowski International Fellowship in Cardiac Pacing and Electrophysiology from Heart Rhythm Society and 2009-2012 American Heart Association Postdoc Fellowship.

Part 1. Surgical preparation
<ol>
	<li>In case programmed electrical stimulation experiments are performed as survival surgeries in mice sterile conditions will be necessary. However, the most common type of experiment is terminal in nature, for which regular clear surgical techniques suffice.</li>
 <li>The mouse is anesthetized using 2% isoflurane in 0.5 L/min 100% O2. </li>
 <li>Hair clippers are used to shave the fur from the neckline to mid chest level.</li>
 <li>The anesthetized mouse is placed in a supine position, with its limbs taped onto ECG electrodes incorporated in a heating board (Indus Instruments, Houston, TX). And the surgical area is disinfected with 10% Povidone Iodine. A recommended system includes a rectal temperature probe connected to a heating pad controlled by a thermoanalyzer system, such that the body temperature is maintained at 37.0 &deg;C &plusmn; 1.0 &deg;C.</li>
</ol>
Part 2. Cannulation and insertion of EP catheter into right atrium and ventricle
<ol>
	<li>After confirming by a toe-pinch that the mouse is fully anesthetized, an 1/2 inch incision is made to the right of the midline with the caudal terminus at the level of the clavicle. </li>
 <li>Subcutaneous tissue, salivary glands, and lymphatic tissues are separated by means of blunt dissection to visualize the right jugular vein. </li>
 <li>The proximal end of the vein is tied with a 6-0 suture. Pulling gently on this suture will keep the internal jugular vein straight while inserting the catheter. Another suture is placed under the vein at the distal end of the visualized segment. This suture will be tied around the catheter once the catheter is placed optimally within the heart, to ensure hemostasis and maintain the catheter in the desired position (Figure 1). </li>
 <li>The computer-based data acquisition is now started to record surface ECG and 4 leads of intracardiac electrograms simultaneously (i.e., IOX-2 acquisition software, Emka Technologies, VA, USA). For intracardiac electrogram recording, electrodes on the catheter are connected to an external stimulator in "recording" mode (i.e., model STG3008, MultiChannel Systems, Reutlingen, Germany). </li>
 <li>Using micro-scissors, a small incision is made in the longitudinal direction of the vein, and the 1.1F octapolar catheter (EPR-800, Millar Instruments, Houston, TX) is advanced through the vein into the right atrium. Gently pulling on the proximal suture will help keep the internal jugular vein straight and will allow easier passage of the catheter into the right atrium and ventricle. Proper catheter position is verified by visualization of the waveforms of the 4 intracardiac electrograms at the level of the apex of the right ventricle, the base of the right ventricle, the atrioventricular node, and the right atrium, respectively (Figure 2). </li>
 <li>The distal suture is now tied off to secure the catheter position and prevent possible bleeding.</li>
</ol>
Part 3. Programmed Electrical Stimulation
<ol>
	<li>In the case of selective atrial pacing, the electrode pair located inside the atrium is switched from "recoding" mode to "stimulation" mode, while the other electrode pairs remain in "recording" mode. </li>
 <li>To determine whether a mouse has an increased vulnerability to atrial arrhythmias, programmed electrical stimulation of the right atrium is performed. First, the atrial pacing threshold is determined by applying 2-ms current pulses (at least 50) at different basic cycle lengths (BCL) to test for consistency of stimulus capture. The BCL of the initial pulse train is slightly lower than the intrinsic BCL, and is decreased by 10 ms (for example, 100 ms, 90 ms, 80 ms, and 70 ms). The typical current amplitude required for stimulus capture is 100-200 &mu;A.</li>
 <li>The sinus node recovery time (SNRT) is measured after applying a 15-s atrial pacing train at a BCL of 100 ms. SNRT is defined as the interval between the last stimulus in the pacing train and the onset of first spontaneous sinus beat. </li>
 <li>The atrial effective refractory period (AERP) is determined by applying series of atrial pacing trains at a fixed BCLs (i.e., 100 ms) with a coupled shorter S2 premature stimulus. The S1-S2 interval is progressively reduced by 2-ms in each pacing train from 70ms to 20ms. The AERP is defined as the longest S1-S2 coupling interval for atria that failed to generate a propagated beat with S2 (S1 being the regular train pulse, and S2 the premature stimulus). Between each stimulation protocol, there was a recovery period of at least 30 seconds.</li>
 <li>The effective refractory period of the atrioventricular (AV) node (AVNERP) is determined by applying series of atrial pacing trains at BCL of 100 ms with a coupled S2 premature stimulus. The S1-S2 interval is progressively reduced by 2 ms each pacing train from 70 ms to 20 ms. The AVNERP is defined as the longest S1-S2 coupling interval at which the premature stimulation delivered to the atrium is followed by a His potential but not by a QRS complex. Between each stimulation protocol, there was a recovery period of at least 30 seconds. </li>
 <li>Inducibility of atrial arrhythmias, including atrial fibrillation (AF), may be tested using the burst pacing protocol described by Verheule et al.2 A series of 2 second bursts is applied to determine inducibility of atrial arrhythmias. The first 2 second burst has a cycle length (CL) of 40 ms, and each successive 2 second burst has a CL of 2-ms shorter than the previous burst, until the final CL of 20 ms. In the absence of an arrhythmogenic substrate, the heart will resume sinus rhythm immediately following the pacing protocol. In the case of atrial flutter, there will be a regular pattern of fast A waves seen on the atrial electrogram, whereas the frequency of the ventricular response is typically slower, as seen on the ventricular electrogram. In case of atrial fibrillation, the surface ECG will show irregular RR intervals in the absence of P waves. Additionally, the atrial electrogram will reveal rapid and irregular A waves, whereas the ventricular electrogram will reveal irregular and slower ventricular waves (Figure 3). Arrhythmia induction protocols are typically performed in triplicate, and an arrhythmia is considered present if it can be evoked in at least 2 out of 3 trials.3,4.</li>
</ol>
Part 4. Removal of Catheter
<ol>
	<li>After all pacing protocols are finished, data acquisition is stopped. The suture at the distal end of the catheter is gently cut off, in order to release the catheter. </li>
 <li>In case of terminal EP studies, the knot is gently loosened to release the catheter.</li>
 <li>At the conclusion of the study, the mouse will be humanely euthanized while under isoflurane using cervical dislocation.</li>
</ol>
Representative Results
Surface ECG and intracardiac electrograms are recorded simultaneously throughout the in vivo electrophysiology study, and are reviewed in detail following the completion of all protocols. The baseline electrophysiological parameters include PR interval, PQ interval, QRS duration, QT intervals, and QRS morphology. These parameters can be measured manually, or automatically using the data acquisition software IOX-2 or ECG-AUTO (Emka Technologies, VA, USA). 
The SNRT, AERP, and AVNERP provide information regarding the sinus node "pacemaker" function, atrial, and AV nodal conduction properties, respectively. Examples of pacing-induced episodes of atrial fibrillation can be found in the paper by Chelu et al.4
<img src="/files/ftp_upload/1730/1730fig1.jpg" alt="Figure 1" /> Figure 1. Illustration of intracardiac catheterization for electrophysiology studies in mice. A. Right internal jugular vein is isolated and cannulated. The distal end of vein is tied off once proper catheter position is achieved. B. The mouse is placed in a supine position for this procedure. C. Cartoon depicting the intracardiac position of catheter. Pair of electrodes are positioned at the level of the apex of the right ventricle, the base of the right ventricle, the atrioventricular node, and the right atrium, respectively. D. Close-up of the 1.1F octapolar catheter. Figure modified from Mathur et al. with permission of Circ Arrhtyhm Electrophys 5.
<img src="/files/ftp_upload/1730/1730fig2.jpg" alt="Figure 2" /> Figure 2. Representative Surface ECG and Intracardiac Electrograms in a Mouse. (A) Surface ECG in lead II configuration showing regular sinus rhythm with a frequency of 540 beats per minute. (B-E) Bipolar intracardiac electrogram recordings at the level of the right atrium (B), atrioventricular node (C), and base of the right ventricle (D), and the apex of the right ventricle (E), respectively. Note that the intracardiac A-wave in panel B corresponds to the P-wave on the surface ECG. The V-wave on the ventricular electrogram corresponds to the QRS wave on the surface ECG.
<img src="/files/ftp_upload/1730/1730fig3.jpg" alt="Figure 3" /> Figure 3. Representative surface ECG and intracardiac electrograms in a mouse that developed atrial fibrillation after atrial burst pacing.

<ol>
	<li>Nattel, S., Shiroshita-Takeshita, A., Brundel, B. J., Rivard, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mechanisms+of+atrial+fibrillation:+lessons+from+animal+models.">Mechanisms of atrial fibrillation: lessons from animal models.</a> Prog Cardiovasc Dis. 48, 9-9 (2005).</li><li>Verheule, S., Sato, T., Everett, T. t., Engle, S. K., Otten, D., Rubart-von der Lohe, M., Nakajima, H. O., Nakajima, H., Field, L. J., Olgin, J. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Increased+vulnerability+to+atrial+fibrillation+in+transgenic+mice+with+selective+atrial+fibrosis+caused+by+overexpression+of+TGF-beta1.">Increased vulnerability to atrial fibrillation in transgenic mice with selective atrial fibrosis caused by overexpression of TGF-beta1.</a> Circ Res. 94, 1458-1458 (2004).</li><li>Sood, S., Chelu, M. G., Oort, R. J. v. a. n., Skapura, D., Santonastasi, M., Dobrev, D., Wehrens, X. H., H, X. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Intracellular+calcium+leak+due+to+FKBP12.6+deficiency+in+mice+facilitates+the+inducibility+of+atrial+fibrillation.">Intracellular calcium leak due to FKBP12.6 deficiency in mice facilitates the inducibility of atrial fibrillation.</a> Heart Rhythm. 5, 1047-1047 (2008).</li><li>Chelu, M. G., Sarma, S., Sood, S., Wang, S., van Oort, R. J., Skapura, D. G., Li, N., Santonastasi, M., Muller, F. U., Schmitz, W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Calmodulin+kinase+II-mediated+sarcoplasmic+reticulum+Ca2++leak+promotes+atrial+fibrillation+in+mice.">Calmodulin kinase II-mediated sarcoplasmic reticulum Ca2+ leak promotes atrial fibrillation in mice.</a> J Clin Invest. 119, 1940-1940 (2009).</li><li>Mathur, N., Subeena, S., Wang, S., van Oort, R. J., Sarma, S., Li, N., Skapura, D., Bayle, J. H., Valderrabano, M., Wehrens, X. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Sudden+Infant+Death+Syndrome+in+Mice+With+an+Inherited+Mutation+in+RyR.">Sudden Infant Death Syndrome in Mice With an Inherited Mutation in RyR.</a> Circ Arrhythmia Electrophysiol. , (2009).</li></ol>

During cardiac catheterization, extensive bleeding during catheterization could increase the heart rate due to hypovolemia. In this case, an intraperitoneal injection of sterile saline (0.3 1.0 mL) could normalize filling pressure and reduce hemodynamic stress in the mouse.
Exposure to isoflurane longer than 2 hours, or higher concentrations of isoflurane (&gt;2 %) could suppress cardiac and respiratory functions in the mouse. Therefore, it is recommended that all studies be completed in le...

programmed electrical stimulation in mice

Genetically-modified mice have emerged as a preferable animal model to study the molecular mechanisms underlying conduction abnormalities, atrial and ventricular arrhythmias, and sudden cardiac death.1 Intracardiac pacing studies can be performed in mice using a 1.1F octapolar catheter inserted into the jugular vein, and advanced into the right atrium and ventricle. Here, we illustrate the steps involved in performing programmed electrical stimulation in mice. Surface ECG and intracardiac electrograms are recorded simultaneously in the atria, atrioventricular junction, and ventricular myocardium, whereas intracardiac pacing of the atrium is performed using an external stimulator. Thus, programmed electrical stimulation in mice provides unique opportunities to explore molecular mechanisms underlying conduction defects and cardiac arrhythmias.

Watch this Scientific Journal Video about Programmed Electrical Stimulation in Mice at JoVE.com

Programmed Electrical Stimulation in Mice

Programmed electrical stimulation provides the ability to determine conduction properties of the heart, and the possibility to induce and terminate cardiac arrhythmias using various pacing protocols. Using a transvenous catheter, intracardiac electrogram recordings can be obtained in mice following programmed electrical stimulation protocols to identify arrhythmogenic substrates.

Genetically-modified mice have emerged as a preferable animal model to study the molecular mechanisms underlying conduction abnormalities, atrial and ...

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20.3K Views.  Baylor College of Medicine (BCM). Programmed electrical stimulation provides the ability to determine conduction properties of the heart, and the possibility to induce and terminate cardiac arrhythmias using various pacing protocols. Using a transvenous catheter, intracardiac electrogram recordings can be obtained in mice following programmed electrical stimulation protocols to identify arrhythmogenic substrates.

Video: Programmed Electrical Stimulation in Mice

Transthoracic Echocardiography in Mice

In recent years, murine models have become the primary avenue for studying the molecular mechanisms of cardiac dysfunction resulting from changes in gene expression. Transgenic and gene targeting methods can be used to generate mice with altered cardiac size and function,1-3 and as a result, in vivo techniques are needed to evaluate their cardiac phenotype. Transthoracic echocardiography, pulse wave Doppler (PWD), and tissue Doppler imaging (TDI) can be used to provide dimensional measurements of the mouse heart and to quantify the degree of cardiac systolic and diastolic performance. Two-dimensional imaging is used to detect abnormal anatomy or movements of the left ventricle, whereas M-mode echo is used for quantification of cardiac dimensions and contractility.4,5 In addition, PWD is used to quantify localized velocity of turbulent flow,6 whereas TDI is used to measure the velocity of myocardial motion.7 Thus, transthoracic echocardiography offers a comprehensive method for the noninvasive evaluation of cardiac function in mice.

Transthoracic echocardiography offers a noninvasive method for the evaluation of cardiac function in mice. A combination of ultrasound and Doppler imaging modalities can be used to obtain dimensional measurements of the heart and intracardiac blood flow, which together provide an assessment of cardiac systolic and diastolic performance.

In recent years, murine models have become the primary avenue for studying the molecular mechanisms of cardiac dysfunction resulting from changes in gene ...

A Murine Model of Muscle Training by Neuromuscular Electrical Stimulation

Neuromuscular electrical stimulation (NMES) is a common clinical modality that is widely used to restore1, maintain2 or enhance3-5 muscle functional capacity. Transcutaneous surface stimulation of skeletal muscle involves a current flow between a cathode and an anode, thereby inducing excitement of the motor unit and the surrounding muscle fibers. 
NMES is an attractive modality to evaluate skeletal muscle adaptive responses for several reasons. First, it provides a reproducible experimental model in which physiological adaptations, such as myofiber hypertophy and muscle strengthening6, angiogenesis7-9, growth factor secretion9-11, and muscle precursor cell activation12 are well documented. Such physiological responses may be carefully titrated using different parameters of stimulation (for Cochrane review, see 13). In addition, NMES recruits motor units non-selectively, and in a spatially fixed and temporally synchronous manner14, offering the advantage of exerting a treatment effect on all fibers, regardless of fiber type. Although there are specified contraindications to NMES in clinical populations, including peripheral venous disorders or malignancy, for example, NMES is safe and feasible, even for those who are ill and/or bedridden and for populations in which rigorous exercise may be challenging. 
Here, we demonstrate the protocol for adapting commercially available electrodes and performing a NMES protocol using a murine model. This animal model has the advantage of utilizing a clinically available device and providing instant feedback regarding positioning of the electrode to elicit the desired muscle contractile effect. For the purpose of this manuscript, we will describe the protocol for muscle stimulation of the anterior compartment muscles of a mouse hindlimb.

A murine model of neuromuscular electrical stimulation (NMES), a safe and inexpensive clinical modality, to the anterior compartment muscles is described. This model has the advantage of modifying a readily available clinical device for the purpose of eliciting targeted and specific muscle contractions in mice.

Neuromuscular electrical stimulation (NMES) is a common clinical modality that is widely used to restore1, maintain2 or enhance3-5 muscle functional ...

Controlled Cervical Laceration Injury in Mice

Use of genetically modified mice enhances our understanding of molecular mechanisms underlying several neurological disorders such as a spinal cord injury (SCI). Freehand manual control used to produce a laceration model of SCI creates inconsistent injuries often associated with a crush or contusion component and, therefore, a novel technique was developed. Our model of cervical laceration SCI has resolved inherent difficulties with the freehand method by incorporating 1) cervical vertebral stabilization by vertebral facet fixation, 2) enhanced spinal cord exposure, and 3) creation of a reproducible laceration of the spinal cord using an oscillating blade with an accuracy of &plusmn;0.01 mm in depth without associated contusion. Compared to the standard methods of creating a SCI laceration such as freehand use of a scalpel or scissors, our method has produced a consistent lesion. This method is useful for studies on axonal regeneration of corticospinal, rubrospinal, and dorsal ascending tracts.

A novel technique to create a reproducible in vivo model of cervical spinal cord laceration injury in the mouse is described. This technique is based on spine stabilization by fixation of the cervical facets and laceration of the spinal cord using an oscillating blade with an accuracy of &plusmn;0.01 mm.

Use of genetically modified mice enhances our  understanding of molecular mechanisms underlying several neurological disorders  such as a spinal cord ...

Breathing-controlled Electrical Stimulation (BreEStim) for Management of Neuropathic Pain and Spasticity

Electrical stimulation (EStim) refers to the application of electrical current to muscles or nerves in order to achieve functional and therapeutic goals. It has been extensively used in various clinical settings. Based upon recent discoveries related to the systemic effects of voluntary breathing and intrinsic physiological interactions among systems during voluntary breathing, a new EStim protocol, Breathing-controlled Electrical Stimulation (BreEStim), has been developed to augment the effects of electrical stimulation. In BreEStim, a single-pulse electrical stimulus is triggered and delivered to the target area when the airflow rate of an isolated voluntary inspiration reaches the threshold. BreEStim integrates intrinsic physiological interactions that are activated during voluntary breathing and has demonstrated excellent clinical efficacy. Two representative applications of BreEStim are reported with detailed protocols: management of post-stroke finger flexor spasticity and neuropathic pain in spinal cord injury.

Breathing-controlled Electrical Stimulation BreEStim for Management of Neuropathic Pain and Spasticity

The purpose is to present a new method, breathing-control electrical stimulation (BreEStim) for management of neuropathic pain and spasticity.

Electrical stimulation (EStim) refers to the application of electrical current to muscles or nerves in order to achieve functional and therapeutic goals. ...

Parabiosis in Mice: A Detailed Protocol

Parabiosis is a surgical union of two organisms allowing sharing of the blood circulation. Attaching the skin of two animals promotes formation of microvasculature at the site of inflammation. Parabiotic partners share their circulating antigens and thus are free of adverse immune reaction. First described by Paul Bert in 18641, the parabiosis surgery was refined by Bunster and Meyer in 1933 to improve animal survival2. In the current protocol, two mice are surgically joined following a modification of the Bunster and Meyer technique. Animals are connected through the elbow and knee joints followed by attachment of the skin allowing firm support that prevents strain on the sutured skin. Herein, we describe in detail the parabiotic joining of a ubiquitous GFP expressing mouse to a wild type (WT) mouse. Two weeks after the procedure, the pair is separated and GFP positive cells can be detected by flow cytometric analysis in the blood circulation of the WT mouse. The blood chimerism allows one to examine the contribution of the circulating cells from one animal in the other.

Parabiotic joining of two organisms leads to the development of a shared circulatory system. In this protocol, we describe the surgical steps to form a parabiotic connection between a wild-type mouse and a constitutive GFP-expressing mouse.

Parabiosis is a surgical union of two organisms allowing sharing of the blood circulation. Attaching the skin of two animals promotes formation of ...

Carotid Artery Infusions for Pharmacokinetic and Pharmacodynamic Analysis of Taxanes in Mice

When proposing the use of a drug, drug combination, or drug delivery into a novel system, one must assess the pharmacokinetics of the drug in the study model. As the use of mouse models are often a vital step in preclinical drug discovery and drug development1-8, it is necessary to design a system to introduce drugs into mice in a uniform, reproducible manner. Ideally, the system should permit the collection of blood samples at regular intervals over a set time course. The ability to measure drug concentrations by mass-spectrometry, has allowed investigators to follow the changes in plasma drug levels over time in individual mice1, 9, 10. In this study, paclitaxel was introduced into transgenic mice as a continuous arterial infusion over three hours, while blood samples were simultaneously taken by retro-orbital bleeds at set time points. Carotid artery infusions are a potential alternative to jugular vein infusions, when factors such as mammary tumors or other obstructions make jugular infusions impractical. Using this technique, paclitaxel concentrations in plasma and tissue achieved similar levels as compared to jugular infusion. In this tutorial, we will demonstrate how to successfully catheterize the carotid artery by preparing an optimized catheter for the individual mouse model, then show how to insert and secure the catheter into the mouse carotid artery, thread the end of the catheter out through the back of the mouse&#8217;s neck, and hook the mouse to a pump to deliver a controlled rate of drug influx. Multiple low volume retro-orbital bleeds allow for analysis of plasma drug concentrations over time.

This method was developed with the goal of delivering a steady drug solution via the carotid artery, to assess the pharmacokinetics of novel drugs in mouse models.

When proposing the use of a drug, drug combination, or drug delivery into a novel system, one must assess the pharmacokinetics of the drug in the study ...

Heterotopic Cervical Heart Transplantation in Mice

The heterotopic cervical heart transplantation in mice is a valuable tool in transplant and cardiovascular research. The cuff technique greatly simplifies this model by avoiding challenging suture anastomoses of small vessels thereby reducing warm ischemia time. In comparison to abdominal graft implantation the cervical model is less invasive and the implanted graft is easily accessible for further follow-up examinations. Anastomoses are performed by pulling the ascending aorta of the graft over the cuff with the recipient&#8217;s common carotid artery and by pulling the main pulmonary artery over the cuff with the external jugular vein. Selection of appropriate cuff size and complete mobilization of the vessels are important for successful revascularization. Ischemia-reperfusion (I/R) injury can be minimized by perfusing the graft with a cardioplegic solution and by hypothermia. In this article, we provide technical details for a simplified and improved cuff technique, which should allow surgeons with basic microsurgical skills to perform the procedure with a high success rate.

The cuff technique shortens and facilitates the model of heterotopic cervical heart transplantation in mice by avoiding technically challenging suture anastomoses of small vessels. The technical details shown in this video paper should allow researches to establish this model in their laboratories.

The heterotopic cervical heart transplantation in mice is a valuable tool in transplant and cardiovascular research. The cuff technique greatly simplifies ...

A Multimodal Imaging- and Stimulation-based Method of Evaluating Connectivity-related Brain Excitability in Patients with Epilepsy

Resting-state functional connectivity MRI (rs-fcMRI) is a technique that identifies connectivity between different brain regions based on correlations over time in the blood-oxygenation level dependent signal. rs-fcMRI has been applied extensively to identify abnormalities in brain connectivity in different neurologic and psychiatric diseases. However, the relationship among rs-fcMRI connectivity abnormalities, brain electrophysiology and disease state is unknown, in part because the causal significance of alterations in functional connectivity in disease pathophysiology has not been established. Transcranial Magnetic Stimulation (TMS) is a technique that uses electromagnetic induction to noninvasively produce focal changes in cortical activity. When combined with electroencephalography (EEG), TMS can be used to assess the brain's response to external perturbations. Here we provide a protocol for combining rs-fcMRI, TMS and EEG to assess the physiologic significance of alterations in functional connectivity in patients with neuropsychiatric disease. We provide representative results from a previously published study in which rs-fcMRI was used to identify regions with abnormal connectivity in patients with epilepsy due to a malformation of cortical development, periventricular nodular heterotopia (PNH). Stimulation in patients with epilepsy resulted in abnormal TMS-evoked EEG activity relative to stimulation of the same sites in matched healthy control patients, with an abnormal increase in the late component of the TMS-evoked potential, consistent with cortical hyperexcitability. This abnormality was specific to regions with abnormal resting-state functional connectivity. Electrical source analysis in a subject with previously recorded seizures demonstrated that the origin of the abnormal TMS-evoked activity co-localized with the seizure-onset zone, suggesting the presence of an epileptogenic circuit. These results demonstrate how rs-fcMRI, TMS and EEG can be utilized together to identify and understand the physiological significance of abnormal brain connectivity in human diseases.

Resting-state functional-connectivity MRI has identified abnormalities in patients with a wide range of neuropsychiatric disorders, including epilepsy due to malformations of cortical development. Transcranial Magnetic Stimulation in combination with EEG can demonstrate that patients with epilepsy have cortical hyperexcitability in regions with abnormal connectivity.

Resting-state functional connectivity MRI (rs-fcMRI) is a technique that identifies connectivity between different brain regions based on correlations ...

Cavernous Nerve Stimulation and Recording of Intracavernous Pressure in a Rat

The stimulation of the cavernous nerve (CN) and measurement of intracavernous pressure (ICP) have been used extensively to test and evaluate therapies for erectile dysfunction. However, the methods used vary between laboratories, and pitfalls still exist. The goal of this study was to describe a surgical technique that would provide a reliable and reproducible model. By exposing the ischiocavernosus muscle at its point of insertion on the ischial tuberosity, the penile crus could be cannulated with minimal dissection and injury to the structures involved in erectile function. Repeated stimulation of the CN, without the need for lifting and drying, was achieved by using a 125 &#181;m bipolar silver electrode and biocompatible silicon glue to isolate the electrode-nerve complex. This method prevents neuropraxia by reducing stretching and drying the nerve and provides complete isolation of the nerve, negating electrical leakage and preventing stimulation of alternative pathways.

This study describes a simplified surgical procedure and technique for performing cavernous nerve stimulation with the isolation of the nerve-electrode complex using silicone glue and intracavernous pressure measurement.

The stimulation of the cavernous nerve (CN) and measurement of intracavernous pressure (ICP) have been used extensively to test and evaluate therapies for ...

Updated Technique for Reliable, Easy, and Tolerated Transcranial Electrical Stimulation Including Transcranial Direct Current Stimulation

Transcranial direct current stimulation (tDCS) is a noninvasive method of neuromodulation using low-intensity direct electrical currents. This method of brain stimulation presents several potential advantages compared to other techniques, as it is noninvasive, cost-effective, broadly deployable, and well-tolerated provided proper equipment and protocols are administered. Even though tDCS is apparently simple to perform, correct administration of the tDCS session, especially the electrode positioning and preparation, is vital for ensuring reproducibility and tolerability. The electrode positioning and preparation steps are traditionally also the most time consuming and error-prone. To address these challenges, modern tDCS techniques, using fixed-position headgear and pre-assembled sponge electrodes, reduce complexity and setup time while also ensuring that the electrodes are consistently placed as intended. These modern tDCS methods present advantages for research, clinic, and remote-supervised (at home) settings. This article provides a comprehensive step-by-step guide for administering a tDCS session using fixed-position headgear and pre-assembled sponge electrodes. This guide demonstrates tDCS using commonly applied montages intended for motor cortex and dorsolateral prefrontal cortex (DLPFC) stimulation. As described, selection of the head size and montage-specific headgear automates electrode positioning. Fully assembled pre-saturated snap-electrodes are simply affixed to the set position snap-connectors on the headgear. The modern tDCS method is shown to reduce setup time and reduce errors for both novice and expert operators. The methods outlined in this article can be adapted to different applications of tDCS as well as other forms of transcranial electrical stimulation (tES) such as transcranial alternating current stimulation (tACS) and transcranial random noise stimulation (tRNS). However, since tES is application specific, as appropriate, any methods recipe is customized to accommodate subject, indication, environment, and outcome specific features.

When administering transcranial direct current stimulation (tDCS), reproducible electrode preparation and placement are vital for a tolerated and effective session. The purpose of this article is to demonstrate updated modern setup procedures for the administration of tDCS and related transcranial electrical stimulation techniques, such as transcranial alternating current stimulation (tACS).

Transcranial direct current stimulation (tDCS) is a noninvasive method of neuromodulation using low-intensity direct electrical currents. This method of ...