We thank Prof. Christine Winter, Julia Klein, Alexandra de Francisco and Yolanda Sierra for their invaluable support in the optimization of the methodology here described.&#160;MLS was supported by the&#160;Ministerio de Ciencia e Innovaci&#243;n, Instituto de Salud Carlos III (project number PI17/01766&#160;and grant number BA21/0030)&#160;co- financed by European Regional Development Fund (ERDF), &#34;A way to make Europe&#34;; CIBERSAM (project number CB07/09/0031); Delegaci&#243;n del Gobierno para el Plan Nacional sobre Drogas (project number 2017/085); Fundaci&#243;n Mapfre; and Fundaci&#243;n Alicia Koplowitz.&#160;MCV was supported by Fundaci&#243;n Tatiana P&#233;rez de Guzm&#225;n el Bueno as scholarship holder of this institution, and EU Joint Programme - Neurodegenerative Disease Research (JPND). DRM was supported by Consejer&#237;a de Educaci&#243;n e Investigaci&#243;n, Comunidad de Madrid, co-funded by European Social Fund &#34;Investing in your future&#34; (grant number PEJD-2018-PRE/BMD-7899). NLR was supported by Instituto de Investigaci&#243;n Sanitaria Gregorio Mara&#241;&#243;n, &#34;Programa Intramural de Impulso a la I+D+I 2019&#34;. MD work was supported by Ministerio de Ciencia e Innovaci&#243;n&#160;(MCIN) and Instituto de Salud Carlos III (ISCIII) (PT20/00044).&#160;The CNIC is supported by the Instituto de Salud Carlos III (ISCIII), the Ministerio de Ciencia e Innovaci&#243;n (MCIN) and the Pro CNIC Foundation, and is a Severo Ochoa Center of Excellence (SEV-2015-0505).

<ol>
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The authors declare that there are no conflicts of interest in connection with this article.

Given the advances in the understanding of brain function and the neural networks involved in the pathophysiology of neuropsychiatric disorders, more and more research is recognizing the potential of DBS in a wide range of neurologically-based pathologies2. However, the mechanism of action of this therapy remains unclear. Several theories have attempted to explain the effects obtained in specific pathological and stimulation circumstances, but the heterogeneity of the proposed studies makes it ver...

The term neurostimulation encompasses a number of different techniques aimed at stimulating the nervous system with a therapeutic objective1. Among them, deep brain stimulation (DBS) stands out as one of the most widespread neurostimulation strategies in clinical practice. DBS consists of the stimulation of deep brain nuclei with electrical pulses delivered by a neurostimulator, implanted directly into the patient&#39;s body, through electrodes placed into the brain target to be modulated by stereotactic surgery. The number of articles evaluating the feasibility of DBS application in different neurological and psychiatric disorders is continuously growing2, although only some of them have been approved by the Food and Drug Association&#160;(FDA) (i.e., essential tremor, Parkinson&#39;s disease, dystonia, obsessive-compulsive disorder, and medically refractory epilepsy)3. Furthermore, a large number of brain targets and stimulation protocols are under research for DBS treatment of many more pathologies than officially approved, but none of them are considered definitive. These inconsistencies in DBS research and clinical procedures may in part be due to a lack of full understanding of its mechanism of action4. Therefore, huge efforts are being made to decipher the in vivo effects of DBS on brain dynamics, as every advance, however small, will help refine DBS protocols for greater therapeutic success.
In this context, molecular imaging techniques open a direct window to observe in vivo neuromodulatory effects of DBS. These approaches provide the opportunity not only to determine the impact of DBS while it is being applied but also to unravel the nature of its consequences, prevent undesired side effects and clinical improvement, and even adapt stimulation parameters to the patient&#39;s needs5. Among these methods, positron emission tomography (PET) using 2-deoxy-2-[18F]fluoro-D-glucose (FDG) is of particular interest because it provides specific and real-time information on the activation state of different brain regions6. Specifically, FDG-PET imaging provides an indirect evaluation of neural activation based on the physiological principle of metabolic coupling between neurons and glial cells6. In this sense, several clinical studies have reported DBS-modulated brain activity patterns using FDG-PET (see3 for review). Nevertheless, clinical studies easily incur several drawbacks when focusing on patients, such as heterogeneity or recruitment difficulties, which strongly limit their research potential6. This context leads researchers to use animal models of human conditions to evaluate biomedical approaches before their clinical translation or, if already applied in clinical practice, to explain the physiological origin of therapeutic benefits or side effects. Thus, despite the large distances between human pathology and the modeled condition in laboratory animals, these preclinical approaches are essential for a safe and effective transition into clinical practice.
This manuscript describes an experimental DBS protocol for murine models, combined with a longitudinal FDG-PET study, in order to assess the acute consequences of DBS on brain metabolism. The outcomes obtained with this protocol may help to unravel the intricate modulatory patterns induced on brain activity by DBS. Therefore, a suitable experimental strategy to examine in vivo the consequences of stimulation is provided, allowing clinicians to anticipate therapeutic effects under specific circumstances and then adapt stimulation parameters to the patient&#39;s needs.

<table><tbody><tr><td>7-Tesla Biospec 70/20 scanner</td><td>Bruker, Germany</td><td>SN0021</td><td>MRI scanner for small animal imaging</td></tr><tr><td>Betadine</td><td>Meda Pharma S.L., Spain</td><td>644625.6</td><td>Iodine solution (iodopovidone)</td></tr><tr><td>Beurer IL 11</td><td>Beurer</td><td>SN87318</td><td>Infra-red light</td></tr><tr><td>Bipolar cable 50 cm w/50 cm mesh covering up to 100 cm</td><td>Plastics One, USA</td><td>305-305 (CM)</td><td></td></tr><tr><td>Bipolar cable TT2&amp;nbsp; 50 cm up to 100 cm</td><td>Plastics One, USA</td><td>305-340/2</td><td>Bipolar cable TT2&amp;nbsp; 50 cm up to 100 cm</td></tr><tr><td>Buprex</td><td>Schering-Plough, S.A</td><td>961425</td><td>Buprenorphine (analgesic)</td></tr><tr><td>Ceftriaxona Reig Jofr&amp;eacute; 1g IM</td><td>Laboratorio Reig Jofr&amp;eacute; S.A., Spain</td><td>624239.1</td><td>Ceftriaxone (antibiotic)</td></tr><tr><td>Commutator</td><td>Plastics One, USA</td><td>SL2+2C</td><td>4 Channel Commutator for DBS</td></tr><tr><td>Concentric bipolar platinum-iridium electrodes</td><td>Plastics One, USA</td><td>MS303/8-AIU/Spc</td><td>Electrodes for DBS</td></tr><tr><td>Driller</td><td>Bosh</td><td>T58704</td><td>Driller</td></tr><tr><td>FDG</td><td>Curium Pharma Spain S.A., Spain</td><td>-----</td><td>2-[18F]fluoro-2-deoxy-D-glucose (PET radiotracer)</td></tr><tr><td>Heating pad</td><td>DAGA, Spain</td><td>23115</td><td>Heating pad</td></tr><tr><td>Ketolar</td><td>Pfizer S.L., Spain</td><td>776211.9</td><td>Ketamine (anesthetic drug)</td></tr><tr><td>Lipolasic 2 mg/g</td><td>Bausch &amp;amp; Lomb S.A, Spain</td><td>65277</td><td>Ophthalmic lubricating gel</td></tr><tr><td>MatLab R2021a</td><td>The MathWorks, Inc</td><td></td><td>Support software for SPM12</td></tr><tr><td>MRIcro</td><td>McCausland Center for Brain Imaging,&amp;nbsp; University of South Carolina, USA</td><td>v2.1.58-0</td><td>Software for imaging preprocessing and analysis</td></tr><tr><td>Multimodality Workstation (MMWKS)</td><td>BiiG, Spain</td><td></td><td>Software for imaging processing and analysis</td></tr><tr><td>Omicrom VISION VET</td><td>RGB Medical Devices, Spain</td><td>731100 ReV B</td><td>Cardiorrespiratory monitor for small imaging</td></tr><tr><td>Prevex Cotton buds</td><td>Prevex, Finland</td><td>-----</td><td>Cotton buds</td></tr><tr><td>Sevorane</td><td>AbbVie Spain, S.L.U, Spain</td><td>673186.4</td><td>Sevoflurane (inhalatory anesthesia)</td></tr><tr><td>Small screws</td><td>Max Witte GmbH</td><td>1,2 x 2 DIN 84 A2</td><td>Small screws</td></tr><tr><td>Standard U-Frame Stereotaxic Instrument for Rat, 18&amp;deg; Ear Bar</td><td>Harvard Apparatus, USA</td><td>75-1801</td><td>Two-arms Stereotactic frame for rat</td></tr><tr><td>Statistical Parametric Mapping (SPM12)</td><td>The Wellcome Center for Human Neuroimaging, UCL Queen Square Institute of Neurology, UK</td><td>SPM12</td><td>Software for voxel-wise imaging analysis</td></tr><tr><td>STG1004</td><td>Multi Channel Systems GmbH, Germany</td><td>STG1004</td><td>Isolated stimulator</td></tr><tr><td>SuperArgus PET/CT scanner</td><td>Sedecal, Spain</td><td>S0026403</td><td>NanoPET/CT scanner for small animal imaging</td></tr><tr><td>Suture thread with needle, 1/&amp;ordm;</td><td>Lorca Mar&amp;iacute;n S.A., Spain</td><td>55325</td><td>Braided natural silk non-absorbable suture 1/0, with triangle needle</td></tr><tr><td>Technovit 4004 (powder and liquid)</td><td>Kulzer Technique, Germany</td><td>64708471; 64708474</td><td>Acrylic dental cement for craniotomy tap</td></tr><tr><td>Wistar rats (&lt;em&gt;Rattus norvergicus&lt;/em&gt;)</td><td>Charles River, Spain</td><td>animal facility</td><td>Animal model used</td></tr><tr><td>Xylagesic</td><td>Laboratorios Karizoo, A.A, Spain</td><td>572599-4</td><td>Xylazine (anesthetic drug)</td></tr><tr><td></td><td>Normon S.A., Spain</td><td>602910</td><td>Mepivacaine in gel for topical use</td></tr></tbody></table>

in vivo positron emission tomography to reveal activity patterns induced by deep brain stimulation in rats

Deep brain stimulation (DBS) is an invasive neurosurgical technique based on the application of electrical pulses to brain structures involved in the patient&#39;s pathophysiology. Despite the long history of DBS, its mechanism of action and appropriate protocols remain unclear, highlighting the need for research aiming to solve these enigmas. In this sense, evaluating the in vivo effects of DBS using functional imaging techniques represents a powerful strategy to determine the impact of stimulation on brain dynamics. Here, an experimental protocol for preclinical models (Wistar rats), combined with a longitudinal study [18F]-fluorodeoxyclucose positron emission tomography (FDG-PET), to assess the acute consequences of DBS on brain metabolism is described. First, animals underwent stereotactic surgery for bilateral implantation of electrodes into the prefrontal cortex. A post-surgical computerized tomography (CT) scan of each animal was acquired to verify electrode placement. After one week of recovery, a first static FDG-PET of each operated animal without stimulation (D1) was acquired, and two days later (D2), a second FDG-PET was acquired while animals were stimulated. For that, the electrodes were connected to an isolated stimulator after administering FDG to the animals. Thus, animals were stimulated during the FDG uptake period (45 min), recording the acute effects of DBS on brain metabolism. Given the exploratory nature of this study, FDG-PET images were analyzed by a voxel-wise approach based on a paired T-test between D1 and D2 studies. Overall, the combination of DBS and imaging studies allows describing the neuromodulation consequences on neural networks, ultimately helping to unravel the conundrums surrounding DBS.

The animals were sacrificed using CO2&#160;at the end of the study or when the animal&#8217;s welfare was compromised. An example of a complete PET/CT study from an operated animal is shown in Figure 3. Thus, the electrode inserted into the rat brain can be clearly observed in the CT image shown in Figure 3A. This imaging modality provides good anatomical information and facilitates the registration of FDG-PET images, given that functional modalities ...

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In vivo Positron Emission Tomography to Reveal Activity Patterns Induced by Deep Brain Stimulation in Rats

We describe a preclinical experimental method to evaluate metabolic neuromodulation induced by acute deep brain stimulation with in vivo FDG-PET. This manuscript includes all experimental steps, from stereotaxic surgery to the application of the stimulation treatment and the acquisition, processing, and analysis of PET images.

In vivo Positron Emission Tomography to Reveal Activity Patterns Induced by Deep Brain Stimulation in Rats

Deep brain stimulation (DBS) is an invasive neurosurgical technique based on the application of electrical pulses to brain structures involved in the ...

in-vivo-positron-emission-tomography-to-reveal-activity-patterns

Research

JoVE Journal

Neuroscience

2.1K Views.  Centro Nacional de Investigaciones Cardiovasculares (CNIC). Dit protocol maakt het mogelijk om de stimulatiegevolgen op neurale netwerken te bestuderen en het raadsel rond DBS te ontrafelen. En om de impact van een stimulatie op de hersendynamiek te bepalen. Het grote voordeel van het gebruik van FD-reparatie tijdens een stimulatie is dat we de in vivo gevolgen van de acute stimulatie op de hersendynamica kunnen visualiseren en vervolgens in vivo de stimulatieprotocollen kunnen verfijnen.Deze methode is van bijzonder belang op het gebied van ne...

Video: In vivo Positron Emission Tomography to Reveal Activity Patterns Induced by Deep Brain Stimulation in Rats

Intra-Operative Behavioral Tasks in Awake Humans Undergoing Deep Brain Stimulation Surgery

Deep brain stimulation (DBS) is a surgical procedure that directs chronic, high frequency electrical stimulation to specific targets in the brain through implanted electrodes. Deep brain stimulation was first implemented as a therapeutic modality by Benabid et al. in the late 1980s, when he used this technique to stimulate the ventral intermediate nucleus of the thalamus for the treatment of tremor 1. Currently, the procedure is used to treat patients who fail to respond adequately to medical management for diseases such as Parkinson's, dystonia, and essential tremor. The efficacy of this procedure for the treatment of Parkinson's disease has been demonstrated in well-powered, randomized controlled trials 2. Presently, the U.S. Food and Drug Administration has approved DBS as a treatment for patients with medically refractory essential tremor, Parkinson's disease, and dystonia. Additionally, DBS is currently being evaluated for the treatment of other psychiatric and neurological disorders, such as obsessive compulsive disorder, major depressive disorder, and epilepsy. 
DBS has not only been shown to help people by improving their quality of life, it also provides researchers with the unique opportunity to study and understand the human brain. Microelectrode recordings are routinely performed during DBS surgery in order to enhance the precision of anatomical targeting. Firing patterns of individual neurons can therefore be recorded while the subject performs a behavioral task. Early studies using these data focused on descriptive aspects, including firing and burst rates, and frequency modulation 3. More recent studies have focused on cognitive aspects of behavior in relation to neuronal activity 4,5. This article will provide a description of the intra-operative methods used to perform behavioral tasks and record neuronal data with awake patients during DBS cases. Our exposition of the process of acquiring electrophysiological data will illuminate the current scope and limitations of intra-operative human experiments.

Deep brain stimulation surgery offers a unique opportunity to examine information encoding in the awake human brain. This article will describe intra-operative methods used to perform cognitive and behavioral tasks while simultaneously acquiring physiological data such as EMG, single-unit neuronal activity and/or local field potentials.

Deep brain stimulation (DBS) is a surgical procedure that directs chronic, high frequency electrical stimulation to specific targets in the brain through ...

Medicine

A General Method for Evaluating Deep Brain Stimulation Effects on Intravenous Methamphetamine Self-Administration

Substance use disorders, particularly to methamphetamine, are devastating, relapsing diseases that disproportionally affect young people. There is a need for novel, effective and practical treatment strategies that are validated in animal models. Neuromodulation, including deep brain stimulation (DBS) therapy, refers to the use of electricity to influence pathological neuronal activity and has shown promise for psychiatric disorders, including drug dependence. DBS in clinical practice involves the continuous delivery of stimulation into brain structures using an implantable pacemaker-like system that is programmed externally by a physician to alleviate symptoms. This treatment will be limited in methamphetamine users due to challenging psychosocial situations. Electrical treatments that can be delivered intermittently, non-invasively and remotely from the drug-use setting will be more realistic. This article describes the delivery of intracranial electrical stimulation that is temporally and spatially separate from the drug-use environment for the treatment of IV methamphetamine dependence. Methamphetamine dependence is rapidly developed in rodents using an operant paradigm of intravenous (IV) self-administration that incorporates a period of extended access to drug and demonstrates both escalation of use and high motivation to obtain drug.

This article describes the delivery of intracranial electrical stimulation that is temporally and spatially separate from the drug-use environment for the treatment of IV methamphetamine dependence.

Substance use disorders, particularly to methamphetamine, are devastating, relapsing diseases that disproportionally affect young people.  There is a need ...

Behavior

A Novel Approach to Assess Motor Outcome of Deep Brain Stimulation Effects in the Hemiparkinsonian Rat: Staircase and Cylinder Test

Deep brain stimulation of the subthalamic nucleus is an effective treatment option for Parkinson&#39;s disease. In our lab we established a protocol to screen different neurostimulation patterns in hemiparkinsonian (unilateral lesioned) rats. It consists of creating a unilateral Parkinson&#39;s lesion by injecting 6-hydroxydopamine (6-OHDA) into the right medial forebrain bundle, implanting chronic stimulation electrodes into the subthalamic nucleus and evaluating motor outcomes at the end of 24 hr periods of cable-bound external neurostimulation. The stimulation was conducted with constant current stimulation. The amplitude was set 20% below the individual threshold for side effects. The motor outcome evaluation was done by the assessment of spontaneous paw use in the cylinder test according to Shallert and by the assessment of skilled reaching in the staircase test according to Montoya. This protocol describes in detail the training in the staircase box, the cylinder test, as well as the use of both in hemiparkinsonian rats. The use of both tests is necessary, because the staircase test seems to be more sensitive for fine motor skill impairment and exhibits greater sensitivity to change during neurostimulation. The combination of the unilateral Parkinson model and the two behavioral tests allows the assessment of different stimulation parameters in a standardized way.

Deep brain stimulation (DBS) is an effective treatment option for Parkinson's disease. We established a study design to screen novel stimulation paradigms in rats. The protocol describes the use of the staircase test and cylinder test for motor outcome assessment in DBS treated hemiparkinsonian rats.

Deep brain stimulation of the subthalamic nucleus is an effective treatment option for Parkinson&#39;s disease. In our lab we established a protocol to ...

Repetitive Transcranial Magnetic Stimulation to the Unilateral Hemisphere of Rat Brain

Previous rodent models of repetitive transcranial magnetic stimulation (rTMS) adopted whole-brain stimulation instead of unilateral hemispheric rTMS, which is unlike the protocols used for human subjects. We report a successful application of rTMS to the unilateral hemisphere of rat brain. The rTMS was delivered with a low-frequency (1 Hz), high-frequency (20 Hz), or sham stimulation protocol to one side of the brain by using a small 25-mm figure-8 coil. We placed the center of the coil 1 cm lateral to the vertex on the biauricular line and angulated the coil 45&#176; to the ground to minimize a potential direct effect of rTMS on the contralateral cortex. We also used an in-house water cooling system to enable repetitive magnetic stimulation for more than 20 min, even at a 20-Hz stimulation frequency. Increases in the transcriptions of immediate early genes (Arc, Junb, and Egr2) were greater after rTMS than after sham stimulation. After 5 consecutive days of 20-min 1-Hz rTMS, bdnf mRNA expression was significantly higher in stimulated cortex than in contralateral side. The model presented herein will elucidate the molecular mechanisms of rTMS by allowing analysis of the inter-hemispheric difference in its effect.

We applied repetitive transcranial magnetic stimulation (rTMS) to the unilateral hemisphere of rat brain, by placing a 25-mm figure-8 coil 1 cm lateral to the vertex on the biauricular line and angulating the coil by 45&#176;. An in-house water cooling system was used for rTMS for more than 20 min.

Previous rodent models of repetitive transcranial magnetic stimulation (rTMS) adopted whole-brain stimulation instead of unilateral hemispheric rTMS, ...

A Wireless, Bidirectional Interface for In Vivo Recording and Stimulation of Neural Activity in Freely Behaving Rats

In vivo electrophysiology is a powerful technique to investigate the relationship between brain activity and behavior at a millisecond and micrometer scale. However, current methods mostly rely on tethered cable recordings or only use unidirectional systems, allowing either recording or stimulation of neural activity, but not at the same time or same target. Here, a new wireless, bidirectional device for simultaneous multichannel recording and stimulation of neural activity in freely behaving rats is described. The system operates through a single portable head stage that both transmits recorded activity and can be targeted in real-time for brain stimulation using a telemetry-based multichannel software. The head stage is equipped with a preamplifier and a rechargeable battery, allowing stable long-term recordings or stimulation for up to 1 h. Importantly, the head stage is compact, weighs 12 g (including battery) and thus has minimal impact on the animal&#180;s behavioral repertoire, making the method applicable to a broad set of behavioral tasks. Moreover, the method has the major advantage that the effect of brain stimulation on neural activity and behavior can be measured simultaneously, providing a tool to assess the causal relationships between specific brain activation patterns and behavior. This feature makes the method particularly valuable for the field of deep brain stimulation, allowing precise assessment, monitoring, and adjustment of stimulation parameters during long-term behavioral experiments. The applicability of the system has been validated using the inferior colliculus as a model structure.

A Wireless, Bidirectional Interface for In Vivo Recording and Stimulation of Neural Activity in Freely Behaving Rats

A wireless, bidirectional system for multi-channel neural recordings and stimulation in freely behaving rats is introduced. The system is light and compact, thus having minimal impact on the animal&#180;s behavioral repertoire. Moreover, this bidirectional system provides a sophisticated tool to assess causal relationships between brain activation patterns and behavior.

In vivo electrophysiology is a powerful technique to investigate the relationship between brain activity and behavior at a millisecond and micrometer ...

Non-invasive Imaging and Analysis of Cerebral Ischemia in Living Rats Using Positron Emission Tomography with 18F-FDG

Stroke is the third leading cause of death among Americans 65 years of age or older1. The quality of life for patients who suffer from a stroke fails to return to normal in a large majority of patients2, which is mainly due to current lack of clinical treatment for acute stroke. This necessitates understanding the physiological effects of cerebral ischemia on brain tissue over time and is a major area of active research. Towards this end, experimental progress has been made using rats as a preclinical model for stroke, particularly, using non-invasive methods such as 18F-fluorodeoxyglucose (FDG) coupled with Positron Emission Tomography (PET) imaging3,10,17. Here we present a strategy for inducing cerebral ischemia in rats by middle cerebral artery occlusion (MCAO) that mimics focal cerebral ischemia in humans, and imaging its effects over 24 hr using FDG-PET coupled with X-ray computed tomography (CT) with an Albira PET-CT instrument. A VOI template atlas was subsequently fused to the cerebral rat data to enable a unbiased analysis of the brain and its sub-regions4. In addition, a method for 3D visualization of the FDG-PET-CT time course is presented. In summary, we present a detailed protocol for initiating, quantifying, and visualizing an induced ischemic stroke event in a living Sprague-Dawley rat in three dimensions using FDG-PET.

Non-invasive Imaging and Analysis of Cerebral Ischemia in Living Rats Using Positron Emission Tomography with 18F-FDG

Brain damage resulting from cerebral ischemia may be non-invasively imaged and studied in rats using pre-clinical positron emission tomography coupled with the injectable radioactive probe, 18F-fluorodeoxyglucose. Further, the use of modern software tools that include volume of interest (VOI) brain templates dramatically increase the quantitative information gleaned from these studies.

Stroke is the third leading cause of death among Americans 65 years of age or older1. The quality of life for patients who suffer from a stroke fails to ...

Deep Brain Stimulation with Simultaneous fMRI in Rodents

In order to visualize the global and downstream neuronal responses to deep brain stimulation (DBS) at various targets, we have developed a protocol for using blood oxygen level dependent (BOLD) functional magnetic resonance imaging (fMRI) to image rodents with simultaneous DBS. DBS fMRI presents a number of technical challenges, including accuracy of electrode implantation, MR artifacts created by the electrode, choice of anesthesia and paralytic to minimize any neuronal effects while simultaneously eliminating animal motion, and maintenance of physiological parameters, deviation from which can confound the BOLD signal.&#160;Our laboratory has developed a set of procedures that are capable of overcoming most of these possible issues. For electrical stimulation, a homemade tungsten bipolar microelectrode is used, inserted stereotactically at the stimulation site in the anesthetized subject. In preparation for imaging, rodents are fixed on a plastic headpiece and transferred to the magnet bore. For sedation and paralysis during scanning, a cocktail of dexmedetomidine and pancuronium is continuously infused, along with a minimal dose of isoflurane; this preparation minimizes the BOLD ceiling effect of volatile anesthetics. In this example experiment, stimulation of the subthalamic nucleus (STN) produces BOLD responses which are observed primarily in ipsilateral cortical regions, centered in motor cortex. Simultaneous DBS and fMRI allows the unambiguous modulation of neural circuits dependent on stimulation location and stimulation parameters, and permits observation of neuronal modulations free of regional bias. This technique may be used to explore the downstream effects of modulating neural circuitry at nearly any brain region, with implications for both experimental and clinical DBS.

This protocol describes a standard method for simultaneous functional magnetic resonance imaging and deep brain stimulation in the rodent. The combined use of these experimental tools allows for the exploration of global downstream activity in response to electrical stimulation at virtually any brain target.

In order to visualize the global and downstream neuronal responses to deep brain stimulation (DBS) at various targets, we have developed a protocol for ...

Analysis of Gene Expression Changes in the Rat Hippocampus After Deep Brain Stimulation of the Anterior Thalamic Nucleus

Deep brain stimulation (DBS) surgery, targeting various regions of the brain such as the basal ganglia, thalamus, and subthalamic regions, is an effective treatment for several movement disorders that have failed to respond to medication. Recent progress in the field of DBS surgery has begun to extend the application of this surgical technique to other conditions as diverse as morbid obesity, depression and obsessive compulsive disorder. Despite these expanding indications, little is known about the underlying physiological mechanisms that facilitate the beneficial effects of DBS surgery. One approach to this question is to perform gene expression analysis in neurons that receive the electrical stimulation. Previous studies have shown that neurogenesis in the rat dentate gyrus is elicited in DBS targeting of the anterior nucleus of the thalamus1. DBS surgery targeting the ATN is used widely for treatment refractory epilepsy. It is thus of much interest for us to explore the transcriptional changes induced by electrically stimulating the ATN. In this manuscript, we describe our methodologies for stereotactically-guided DBS surgery targeting the ATN in adult male Wistar rats. We also discuss the subsequent steps for tissue dissection, RNA isolation, cDNA preparation and quantitative RT-PCR for measuring gene expression changes. This method could be applied and modified for stimulating the basal ganglia and other regions of the brain commonly clinically targeted. The gene expression study described here assumes a candidate target gene approach for discovering molecular players that could be directing the mechanism for DBS.

The mechanism underlying the therapeutic effects of Deep Brain Stimulation (DBS) surgery needs investigation. The methods presented in this manuscript describe an experimental approach to examine the cellular events triggered by DBS by analyzing the gene expression profile of candidate genes that can facilitate neurogenesis post DBS surgery.

Deep brain stimulation (DBS) surgery, targeting various regions of the brain such as the basal ganglia, thalamus, and subthalamic regions, is an effective ...

Microelectrode Guided Implantation of Electrodes into the Subthalamic Nucleus of Rats for Long-term Deep Brain Stimulation

Deep brain stimulation (DBS) is a widely used and effective therapy for several neurologic disorders, such as idiopathic Parkinson&#8217;s disease, dystonia or tremor. DBS is based on the delivery of electrical stimuli to specific deep anatomic structures of the central nervous system. However, the mechanisms underlying the effect of DBS remain enigmatic. This has led to an interest in investigating the impact of DBS in animal models, especially in rats. As DBS is a long-term therapy, research should be focused on molecular-genetic changes of neural circuits that occur several weeks after DBS. Long-term DBS in rats is challenging because the rats move around in their cage, which causes problems in keeping in place the wire leading from the head of the animal to the stimulator. Furthermore, target structures for stimulation in the rat brain are small and therefore electrodes cannot easily be placed at the required position. Thus, a set-up for long-lasting stimulation of rats using platinum/iridium electrodes with an impedance of about 1 M&#937; was developed for this study. An electrode with these specifications allows for not only adequate stimulation but also recording of deep brain structures to identify the target area for DBS. In our set-up, an electrode with a plug for the wire was embedded in dental cement with four anchoring screws secured onto the skull. The wire from the plug to the stimulator was protected by a stainless-steel spring. A swivel was connected to the circuit to prevent the wire from becoming tangled. Overall, this stimulation set-up offers a high degree of free mobility for the rat and enables the head plug, as well as the wire connection between the plug and the stimulator, to retain long-lasting strength.

A method for implanting electrodes into the subthalamic nucleus (STN) of rats is described. Better localization of the STN was achieved by using a microrecording system. Furthermore, a stimulation set-up is presented that is characterized by long-lasting connections between the head of the animal and the stimulator.

Deep brain stimulation (DBS) is a widely used and effective therapy for several neurologic disorders, such as idiopathic Parkinson&#8217;s disease, ...

Acute In Vivo Electrophysiological Recordings of Local Field Potentials and Multi-unit Activity from the Hyperdirect Pathway in Anesthetized Rats

Converging evidence shows that many neuropsychiatric diseases should be understood as disorders of large-scale neuronal networks. To better understand the pathophysiological basis of these diseases, it is necessary to precisely characterize in which way the processing of information is disturbed between the different neuronal parts of the circuit. Using extracellular in vivo electrophysiological recordings, it is possible to accurately delineate neuronal activity within a neuronal network. The application of this method has several advantages over alternative techniques, e.g., functional magnetic resonance imaging and calcium imaging, as it allows a unique temporal and spatial resolution and does not rely on genetically engineered organisms. However, the use of extracellular in vivo recordings is limited since it is an invasive technique that cannot be universally applied. In this article, a simple and easy to use method is presented with which it is possible to simultaneously record extracellular potentials such as local field potentials and multiunit activity at multiple sites of a network. It is detailed how a precise targeting of subcortical nuclei can be achieved using a combination of stereotactic surgery and online analysis of multi-unit recordings. Thus, it is demonstrated, how a complete network such as the hyperdirect cortico-basal ganglia loop can be studied in anesthetized animals in vivo.

Acute In Vivo Electrophysiological Recordings of Local Field Potentials and Multi-unit Activity from the Hyperdirect Pathway in Anesthetized Rats

In this study, the methodology is presented on how to perform multi-site in vivo electrophysiological recordings from the hyperdirect pathway under urethane anesthesia.

Converging evidence shows that many neuropsychiatric diseases should be understood as disorders of large-scale neuronal networks. To better understand the ...

In vivo Positron Emission Tomography to Reveal Activity Patterns Induced by Deep Brain Stimulation in Rats

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