Portable microstimulator for chronic deep brain stimulation in freely moving rats

Experimental deep brain stimulation in rodent models of movement disorders

Deep brain stimulation (DBS) is the preferred treatment for therapy-resistant movement disorders such as dystonia and Parkinson's disease (PD), mostly in advanced disease stages. Although DBS is already in clinical use for ~30 years and has improved patients' quality of life dramatically, there is still limited understanding of the underlying mechanisms of action. Rodent models of PD and dystonia are essential tools to elucidate the mode of action of DBS on behavioral and multiscale neurobiological levels. Advances have been made in identifying DBS effects on the central motor network, neuroprotection and neuroinflammation in DBS studies of PD rodent models. The phenotypic dt^sz mutant hamster and the transgenic DYT-TOR1A (ΔETorA) rat proved as valuable models of dystonia for preclinical DBS research. In addition, continuous refinements of rodent DBS technologies are ongoing and have contributed to improvement of experimental quality. We here review the currently existing literature on experimental DBS in PD and dystonia models regarding the choice of models, experimental design, neurobiological readouts, as well as methodological implications. Moreover, we provide an overview of the technical stage of existing DBS devices for use in rodent studies.

The software defined implantable modular platform (STELLA) for preclinical deep brain stimulation research in rodents

Context.Long-term deep brain stimulation (DBS) studies in rodents are of crucial importance for research progress in this field. However, most stimulation devices require jackets or large head-mounted systems which severely affect mobility and general welfare influencing animals' behavior.Objective.To develop a preclinical neurostimulation implant system for long-term DBS research in small animal models.Approach.We propose a low-cost dual-channel DBS implant called software defined implantable platform (STELLA) with a printed circuit board size of Ø13 × 3.3 mm, weight of 0.6 g and current consumption of 7.6µA/3.1 V combined with an epoxy resin-based encapsulation method.Main results.STELLA delivers charge-balanced and configurable current pulses with widely used commercial electrodes. Whilein vitrostudies demonstrate at least 12 weeks of error-free stimulation using a CR1225 battery, our calculations predict a battery lifetime of up to 3 years using a CR2032. Exemplary application for DBS of the subthalamic nucleus in adult rats demonstrates that fully-implanted STELLA neurostimulators are very well-tolerated over 42 days without relevant stress after the early postoperative phase resulting in normal animal behavior. Encapsulation, external control and monitoring of function proved to be feasible. Stimulation with standard parameters elicited c-Fos expression by subthalamic neurons demonstrating biologically active function of STELLA.Significance.We developed a fully implantable, scalable and reliable DBS device that meets the urgent need for reverse translational research on DBS in freely moving rodent disease models including sensitive behavioral experiments. We thus add an important technology for animal research according to 'The Principle of Humane Experimental Technique'-replacement, reduction and refinement (3R). All hardware, software and additional materials are available under an open source license.

Deep brain stimulation in Alzheimer's disease

Benefits from symptomatic and etiologic treatments in Alzheimer's Disease (AD), the most frequent dementia, are still insufficient. During the last decade, several studies showed that electrical stimulation of memory circuits could enhance memory in humans without memory impairment. First, improvement of verbal recollection was reported after deep brain stimulation (DBS) of the fornix in the hypothalamus in a patient treated for morbid obesity. Several studies in epileptic patients explored by deep electrodes reported that visuo-spatial memorization was facilitated by electrical stimulation of the entorhinal cortex or theta burst stimulation of the fornix. Recent studies suggested that DBS could be useful to modulate memory circuits in patients with cognitive decline. Phase I and II studies (about 50 patients) showed that chronic fornix DBS was safe and could achieved to stabilize or slow the memory decline of some patients with mild to moderate AD, especially older ones with less severe and/or advanced disease. DBS of the cholinergic nucleus of Meynert also has been explored in phase I studies in AD and Parkinson-related dementia. Growing experimental data suggest several mechanisms of action: restoration of hippocampal theta rhythms, enhanced long term potentiation, increase of hippocampal neurogenesis, neuroprotection by release of neurotrophic factors, diffuse reactivation of hypoactive neocortical associative regions. However, DBS in AD is still investigational and numerous issues remain to be solved before envisaging its use in clinical practice, including optimal anatomical DBS target, stimulation modalities (continuous, intermittent, theta-bursts, closed loop stimulation), best candidate patients, relevant targeted symptoms, ethical considerations.

Directions of Deep Brain Stimulation for Epilepsy and Parkinson's Disease

BACKGROUND

Deep brain stimulation (DBS) is an effective treatment for movement disorders and neurological/psychiatric disorders. DBS has been approved for the control of Parkinson disease (PD) and epilepsy.

OBJECTIVES

A systematic review and possible future direction of DBS system studies is performed in the open loop and closed-loop configuration on PD and epilepsy.

METHODS

We searched Google Scholar database for DBS system and development. DBS search results were categorized into clinical device and research system from the open-loop and closed-loop perspectives.

RESULTS

We performed literature review for DBS on PD and epilepsy in terms of system development by the open loop and closed-loop configuration. This study described development and trends for DBS in terms of electrode, recording, stimulation, and signal processing. The closed-loop DBS system raised a more attention in recent researches.

CONCLUSION

We overviewed development and progress of DBS. Our results suggest that the closed-loop DBS is important for PD and epilepsy.

Towards chronic deep brain stimulation in freely moving hemiparkinsonian rats: Applicability and functionality of a fully implantable stimulation system

Objective This study aimed at investigating a novel fully implantable deep brain stimulation system and its ability to modulate brain metabolism and behavior through subthalamic nucleus stimulation in a hemiparkinsonian rat model. Approach Twelve male rats were unilaterally lesioned with 6-hydroxydopamine in the medial forebrain bundle and received a fully implantable deep brain stimulation system aiming at the ipsilesional subthalamic nucleus. Each rat underwent three cylinder tests to analyze front paw use: A PRE test before any surgical intervention, an OFF test after surgery but before stimulation onset and an ON test under deep brain stimulation. To visualize brain glucose metabolism in the awake animal, two [18F]FDG scans were conducted in the OFF and ON condition. At least four weeks after surgery, an [18F]FDOPA scan was used to check for dopaminergic integrity. Main results In general, STN DBS increased [18F]FDG uptake ipsilesionally and decreased it contralesionally. More specifically, bilateral orbitofrontal cortex, ipsilateral caudate putamen, sensorimotor cortex and nucleus accumbens showed significantly higher tracer uptake in ON compared to OFF condition. Contralateral cingulate and secondary motor cortex, caudate putamen, amygdala, hippocampus, retrosplenial granular cortex, superior colliculus, and parts of the cerebellum exhibited significantly higher [18F]FDG uptake in the OFF condition. On the behavioral level, stimulation was able improve use of the contralesional affected front paw suggesting an effective stimulation produced by the implanted system. Significance The fully implantable stimulation system developed by us and presented here offers the output of arbitrary user-defined waveforms, patterns and stimulation settings and allows tracer accumulation in freely moving animals. It is therefore a suitable device for implementing behavioral PET studies. It contributes immensely to the possibilities to characterize and unveil the effects and mechanisms of deep brain stimulation offering valuable clues for future improvements of this therapy.

Development of a Fully Implantable Stimulator for Deep Brain Stimulation in Mice

INTRODUCTION

Deep brain stimulation is an established method for the treatment of neurological and psychiatric disorders. To elicit the underlying mechanisms and explore new stimulation targets, rodent models are necessary. Cable bound external stimulation or portable devices limit movement of the animals and influence behavioral experiments. Therefore, implantable, individually programmed devices are required.

EXPERIMENTAL PROCEDURE

The stimulator consists of an 8bit-microcontroller mounted on a square electrical board (10 × 10 mm). External control is enabled by a magnetic reed contact, as running control serves a white LED, running modes are displayed by flash codes. Stimulation parameters could be programmed in the range of pulse width: 60-500 μs, amplitude: up to 300 μA and frequency: 10-500 Hz. Power is supplied by two standard batteries. The device was implanted in 8-10 weeks old BALBc-mice. Functionality was examined by electrical stimulation of nucleus accumbens area with standard parameters for mice and determination of c-fos levels in vitro in brain slices.

RESULTS

The implanted microstimulators were well-tolerated by the mice, without impairment of free movement. Coating, external control, and monitoring of function with LED flash code proved to be fully adequate. Stimulation with standard stimulating parameters of nucleus accumbens elicited strong c-fos elevation on simulation site.

CONCLUSION

We present a fully implantable stimulator for freely moving mice that meets the urgent need for further research on the effects of deep brain stimulation in rodent models. It offers the possibility to conduct behavioral experiments for up to 30 days of stimulation.

In vivo validation of a new portable stimulator for chronic deep brain stimulation in freely moving rats

BACKGROUND

Deep brain stimulation (DBS) of the subthalamic nucleus (STN) is considered as a gold standard therapy for the alleviation of motor symptoms in Parkinson's disease (PD). This success paved the way to its application for other neurological and psychiatric disorders. In this context, we aimed to develop a rodent-specific stimulator with characteristics similar to those used in patients.

NEW METHOD

We designed a stimulator that can be connected to an electrode container with options for bilateral or unilateral stimulation selection and offers a wide range of frequencies, pulse widths and intensities, constant current, biphasic current-control and charge balancing. Dedicated software was developed to program these parameters and the device was tested on a bilateral 6-hydroxydopamine (6-OHDA) rat model of PD.

RESULTS

The equipment was well tolerated by the animals with a good general welfare. STN stimulation (130 Hz frequency, 0.06 ms pulse width, 150 μA average intensity) improved the motor deficits induced by 6-OHDA as it significantly increased the number of movements compared to the values obtained in the same animals without STN stimulation. Furthermore, it restored motor coordination by significantly increasing the time spent on the rotarod bar.

CONCLUSION

We successfully developed and validated a new portable and programmable stimulator for freely moving rats that delivers a large range of stimulation parameters using bilateral biphasic current-control and charge balancing to maximize tissue safety. This device can be used to test deep brain stimulation in different animal models of human brain diseases.

Chronic fornix deep brain stimulation in a transgenic Alzheimer's rat model reduces amyloid burden, inflammation, and neuronal loss

Recent studies have suggested deep brain stimulation (DBS) as a promising therapy in patients with Alzheimer's disease (AD). Particularly, the stimulation of the forniceal area was found to slow down the cognitive decline of some AD patients, but the biochemical and anatomical modifications underlying these effects remain poorly understood. We evaluated the effects of chronic forniceal stimulation on amyloid burden, inflammation, and neuronal loss in a transgenic Alzheimer rat model TgF344-AD, as well as in age-matched control rats. 18-month-old rats were surgically implanted with electrodes in stereotactic conditions and connected to a portable microstimulator for chronic DBS in freely moving rats. The stimulation was continuous during 5 weeks and animals were immediately sacrificed for immunohistochemical analysis of pathological markers. Implanted, but non-stimulated rats were used as controls. We found that chronic forniceal DBS in the Tg-AD rat significantly reduces amyloid deposition in the hippocampus and cortex, decreases astrogliosis and microglial activation and lowers neuronal loss, as determined by NeuN staining. In control animals, the stimulation neither affects neuroinflammation nor neuronal count. In the Tg-F344-AD rat model, 5 weeks of forniceal DBS decreased amyloidosis, inflammatory responses, and neuronal loss in both cortex and hippocampus. These findings strongly suggest a neuroprotective effect of DBS and support the beneficial effects of targeting the fornix in Alzheimer's disease patients.

A Miniaturized, Programmable Deep-Brain Stimulator for Group-Housing and Water Maze Use

Pre-clinical deep-brain stimulation (DBS) research has observed a growing interest in the use of portable stimulation devices that can be carried by animals. Not only can such devices overcome many issues inherent with a cable tether, such as twisting or snagging, they can also be utilized in a greater variety of arenas, including enclosed or large mazes. However, these devices are not inherently designed for water-maze environments, and their use has been restricted to individually-housed rats in order to avoid damage from various social activities such as grooming, playing, or fighting. By taking advantage of 3D-printing techniques, this study demonstrates an ultra-small portable stimulator with an environmentally-protective device housing, that is suitable for both social-housing and water-maze environments. The miniature device offers 2 channels of charge-balanced biphasic pulses with a high compliance voltage (12 V), a magnetic switch, and a diverse range of programmable stimulus parameters and pulse modes. The device's capabilities have been verified in both chronic pair-housing and water-maze experiments that asses the effects of nucleus reuniens DBS. Theta-burst stimulation delivered during a reference-memory water-maze task (but not before) had induced performance deficits during both the acquisition and probe trials of a reference memory task. The results highlight a successful application of 3D-printing for expanding on the range of measurement modalities capable in DBS research.

Development of a head-mounted wireless microstimulator for deep brain stimulation in rats

BACKGROUND

Commercial neurostimulators for clinical use are effective in patients; however they are too large and prohibitively expensive for preclinical studies. Thus, there is an urgent need of a small inexpensive and wireless microstimulator which is fully programmable in frequency, pulse width and amplitude for rodent experiments.

NEW METHODS

Rats were subjected to a photothrombotic stroke of the right sensorimotor cortex and a microelectrode was implanted in the right mesencephalic locomotor region. The microstimulator was connected with the head plug of the rat. Three different stimulation frequencies were applied and different stimulating amplitudes were chosen. Under these conditions, gait velocity and locomotor behavior of six rats were examined on a beam.

RESULTS

The head-mounted microstimulator allowed freedom in all motor activities performed spontaneously by the tested rats. Increasing either the frequency or the stimulating amplitude increased gait velocity and ameliorated locomotor behavior after stroke.

COMPARISON WITH EXISTING METHODS

Other devices for DBS in rodents must be implanted under the skin or worn in an animal jacket on the back by the tested rat. Some available systems require even a tethering of the tested animal via a cable to an external stimulation system, which limits the freedom of movement.

CONCLUSION

Here, we present a freely programmable microstimulator including DBS-typical stimulating parameters. The lightweight device is connected by a simple plug to the head allowing full freedom of movement and exchange of batteries for long-term experiments. The design of this stimulator is suitable for sophisticated behavior tests requiring balance and skilled walking.

Deep Brain Stimulation of Hemiparkinsonian Rats with Unipolar and Bipolar Electrodes for up to 6 Weeks: Behavioral Testing of Freely Moving Animals

Although the clinical use of deep brain stimulation (DBS) is increasing, its basic mechanisms of action are still poorly understood. Platinum/iridium electrodes were inserted into the subthalamic nucleus of rats with unilateral 6-OHDA-induced lesions of the medial forebrain bundle. Six behavioral parameters were compared with respect to their potential to detect DBS effects. Locomotor function was quantified by (i) apomorphine-induced rotation, (ii) initiation time, (iii) the number of adjusting steps in the stepping test, and (iv) the total migration distance in the open field test. Sensorimotor neglect and anxiety were quantified by (v) the retrieval bias in the corridor test and (vi) the ratio of migration distance in the center versus in the periphery in the open field test, respectively. In our setup, unipolar stimulation was found to be more efficient than bipolar stimulation for achieving beneficial long-term DBS effects. Performance in the apomorphine-induced rotation test showed no improvement after 6 weeks. DBS reduced the initiation time of the contralateral paw in the stepping test after 3 weeks of DBS followed by 3 weeks without DBS. Similarly, sensorimotor neglect was improved. The latter two parameters were found to be most appropriate for judging therapeutic DBS effects.

An implantable device for neuropsychiatric rehabilitation by chronic deep brain stimulation in freely moving rats

Successful practice of clinical deep brain stimulation (DBS) calls for basic research on the mechanisms and explorations of new indications in animals. In the article, a new implantable, single-channel, low-power miniature device is proposed, which may transmit pulses chronically into the brain nucleus of freely moving rats. The DBS system consists of an implantable pulse generator (IPG), a bipolar electrode, and an external programmer. The IPG circuit module is assembled as a 20-mm diameter circular board and fixed on a rat’s skull together with an electrode and battery. The rigid electrode may make its fabrication and implantation more easy. The external programmer is designed for bidirectional communication with the IPG by a telecontrol transceiver and adjusts stimulation parameters. A biological validation was performed in which the effects of electrical stimulation in brain nucleus accumbens were detected. The programmed parameters were accurate, implant steady, and power sufficient to allow stimulation for more than 3 months. The larger area of the electrode tip provided a moderate current or charge density and minimized the damage from electrochemistry and pyroelectricity. The rats implanted with the device showed a reduction in morphine-induced conditioned place preference after high-frequency stimulation. In conclusion, the DBS device is based on the criteria of simple technology, minimal invasion, low cost, small in size, light-weight, and wireless controlled. This shows that our DBS device is appropriate and can be used for preclinical studies, indicating its potential utility in the therapy and rehabilitation of neuropsychiatric disorders.

Validation of a Portable Low-Power Deep Brain Stimulation Device Through Anxiolytic Effects in a Laboratory Rat Model

Deep brain stimulation (DBS) devices deliver electrical pulses to neural tissue through an electrode. To study the mechanisms and therapeutic benefits of deep brain stimulation, murine preclinical research is necessary. However, conducting naturalistic long-term, uninterrupted animal behavioral experiments can be difficult with bench-top systems. The reduction of size, weight, power consumption, and cost of DBS devices can assist the progress of this research in animal studies. A low power, low weight, miniature DBS device is presented in this paper. This device consists of electronic hardware and software components including a low-power microcontroller, an adjustable current source, an n-channel metal-oxide-semiconductor field-effect transistor, a coin-cell battery, electrode wires and a software program to operate the device. Evaluation of the performance of the device in terms of battery lifetime and device functionality through bench and in vivo tests was conducted. The bench test revealed that this device can deliver continuous stimulation current pulses of strength [Formula: see text], width [Formula: see text], and frequency 130 Hz for over 22 days. The in vivo tests demonstrated that chronic stimulation of the nucleus accumbens (NAc) with this device significantly increased psychomotor activity, together with a dramatic reduction in anxiety-like behavior in the elevated zero-maze test.

An Embedded Deep Brain Stimulator for Biphasic Chronic Experiments in Freely Moving Rodents

This paper describes a Deep Brain Stimulation device, portable, for chronic experiments on rodents in the context of Parkinson's disease. Our goal is to equip the animal with a device that mimics the human therapeutic conditions. It implies to respect a set of properties such as bilateral current-mode and charge-balanced stimulation, as well as programmability, low power consumption and re-usability to finally reach a suitable weight for long-term experiments. After the analysis of the solutions found in the literature, the full design of the device is explained. First, the stimulation front-end circuit driven by a processor unit, then the choice of supply sources which is a critical point for the weight and life-time of our system. Our low cost system has been realized using commercial discrete components and the overall power consumption was minimized. We achieved 6 days of maximal current stimulation with the chosen battery for a weight of 13.8 g . Finally, the device was carried out in vivo on rats during a 3 weeks experiment as the used implantation technique allows battery changing. This experiment also permits to emphasize the mechanical aspects including the packaging and electrodes holding.

Metabolic, synaptic and behavioral impact of 5-week chronic deep brain stimulation in hemiparkinsonian rats

The long-term effects and action mechanisms of subthalamic nucleus (STN) high-frequency stimulation (HFS) for Parkinson's disease still remain poorly characterized, mainly due to the lack of experimental models relevant to clinical application. To address this issue, we performed a multilevel study in freely moving hemiparkinsonian rats undergoing 5-week chronic STN HFS, using a portable constant-current microstimulator. In vivo metabolic neuroimaging by (1) H-magnetic resonance spectroscopy (11.7 T) showed that STN HFS normalized the tissue levels of the neurotransmission-related metabolites glutamate, glutamine and GABA in both the striatum and substantia nigra reticulata (SNr), which were significantly increased in hemiparkinsonian rats, but further decreased nigral GABA levels below control values; taurine levels, which were not affected in hemiparkinsonian rats, were significantly reduced. Slice electrophysiological recordings revealed that STN HFS was, uniquely among antiparkinsonian treatments, able to restore both forms of corticostriatal synaptic plasticity, i.e. long-term depression and potentiation, which were impaired in hemiparkinsonian rats. Behavior analysis (staircase test) showed a progressive recovery of motor skill during the stimulation period. Altogether, these data show that chronic STN HFS efficiently counteracts metabolic and synaptic defects due to dopaminergic lesion in both the striatum and SNr. Comparison of chronic STN HFS with acute and subchronic treatment further suggests that the long-term benefits of this treatment rely both on the maintenance of acute effects and on delayed actions on the basal ganglia network. We studied the effects of chronic (5 weeks) continuous subthalamic nucleus (STN) high-frequency stimulation (HFS) in hemiparkinsonian rats. The levels of glutamate and GABA in the striatum () and substantia nigra reticulata (SNr) (), measured by in vivo proton magnetic resonance spectroscopy ((1) H-MRS), were increased by 6-hydroxydopamine (6-OHDA) lesion, which also disrupted corticostriatal synaptic plasticity () and impaired forepaw skill () in the staircase test. Five-week STN HFS normalized glutamate and GABA levels and restored both synaptic plasticity and motor function. A partial behavioral recovery was observed at 2-week STN HFS.

Neurosurgery planning in rodents using a magnetic resonance imaging assisted framework to target experimentally defined networks

BACKGROUND AND OBJECTIVE

Meaningful targeting of brain structures is required in a number of experimental designs in neuroscience. Current technological developments as high density electrode arrays for parallel electrophysiological recordings and optogenetic tools that allow fine control of activity in specific cell populations provide powerful tools to investigate brain physio-pathology. However, to extract the maximum yield from these fine developments, increased precision, reproducibility and cost-efficiency in experimental procedures is also required.

METHODS

We introduce here a framework based on magnetic resonance imaging (MRI) and digitized brain atlases to produce customizable 3D-environments for brain navigation. It allows the use of individualized anatomical and/or functional information from multiple MRI modalities to assist experimental neurosurgery planning and in vivo tissue processing.

RESULTS

As a proof of concept we show three examples of experimental designs facilitated by the presented framework, with extraordinary applicability in neuroscience.

CONCLUSIONS

The obtained results illustrate its feasibility for identifying and selecting functionally and/or anatomically connected neuronal population in vivo and directing electrode implantations to targeted nodes in the intricate system of brain networks.

An Implantable Versatile Electrode-Driving ASIC for Chronic Epidural Stimulation in Rats

This paper presents the design and testing of an electrode driving application specific integrated circuit (ASIC) intended for epidural spinal cord electrical stimulation in rats. The ASIC can deliver up to 1 mA fully programmable monophasic or biphasic stimulus current pulses, to 13 electrodes selected in any possible configuration. It also supports interleaved stimulation. Communication is achieved via only 3 wires. The current source and the control of the stimulation timing were kept off-chip to reduce the heat dissipation close to the spinal cord. The ASIC was designed in a 0.18- μm high voltage CMOS process. Its output voltage compliance can be up to 25 V. It features a small core area (<;0.36 mm(2)) and consumes a maximum of 114 μW during a full stimulation cycle. The layout of the ASIC was developed to be suitable for integration on the epidural electrode array, and two different versions were fabricated and electrically tested. Results from both versions were almost indistinguishable. The performance of the system was verified for different loads and stimulation parameters. Its suitability to drive a passive epidural 12-electrode array in saline has also been demonstrated.

A novel combinational approach of microstimulation and bioluminescence imaging to study the mechanisms of action of cerebral electrical stimulation in mice

Deep brain stimulation (DBS) is used to treat a number of neurological conditions and is currently being tested to intervene in neuropsychiatric conditions. However, a better understanding of how it works would ensure that side effects could be minimized and benefits optimized. We have thus developed a unique device to perform brain stimulation (BS) in mice and to address fundamental issues related to this methodology in the pre-clinical setting. This new microstimulator prototype was specifically designed to allow simultaneous live bioluminescence imaging of the mouse brain, allowing real time assessment of the impact of stimulation on cerebral tissue. We validated the authenticity of this tool in vivo by analysing the expression of toll-like receptor 2 (TLR2), corresponding to the microglial response, in the stimulated brain regions of TLR2-fluc-GFP transgenic mice, which we further corroborated with post-mortem analyses in these animals as well as in human brains of patients who underwent DBS to treat their Parkinson's disease. In the present study, we report on the development of the first BS device that allows for simultaneous live in vivo imaging in mice. This tool opens up a whole new range of possibilities that allow a better understanding of BS and how to optimize its effects through its use in murine models of disease.

An inexpensive, charge-balanced rodent deep brain stimulation device: a step-by-step guide to its procurement and construction

BACKGROUND

Despite there being a relatively large number of methods papers which detail specifically the development of stimulation devices, only a small number of reports involve the application of these devices in freely moving animals. To date multiple preclinical neural stimulators have been designed and described but have failed to make an impact on the methods employed by the majority of laboratories studying DBS. Thus, the overwhelming majority of DBS studies are still performed by tethering the subject to an external stimulator. We believe that the low adoption rate of previously described methods is a result of the complexity of replicating and implementing these methods.

NEW METHOD

Here were describe both the design and procurement of a simple and inexpensive stimulator designed to be compatible with commonly used, commercially available electrodes (Plastics 1).

RESULTS

This system is initially programmable in frequency, pulsewidth and current amplitude, and delivers biphasic, charge-balanced output to two independent electrodes.

COMPARISON WITH EXISTING METHOD(S)

It is easy to implement requiring neither subcutaneous implantation nor custom-made electrodes and has been optimized for either direct mounting to the head or for use with rodent jackets.

CONCLUSIONS

This device is inexpensive and universally accessible, facilitating high throughput, low cost, long-term rodent deep brain stimulation experiments.

A Low Power Micro Deep Brain Stimulation Device for Murine Preclinical Research

Deep brain stimulation has emerged as an effective medical procedure that has therapeutic efficacy in a number of neuropsychiatric disorders. Preclinical research involving laboratory animals is being conducted to study the principles, mechanisms, and therapeutic effects of deep brain stimulation. A bottleneck is, however, the lack of deep brain stimulation devices that enable long term brain stimulation in freely moving laboratory animals. Most of the existing devices employ complex circuitry, and are thus bulky. These devices are usually connected to the electrode that is implanted into the animal brain using long fixed wires. In long term behavioral trials, however, laboratory animals often need to continuously receive brain stimulation for days without interruption, which is difficult with existing technology. This paper presents a low power and lightweight portable microdeep brain stimulation device for laboratory animals. Three different configurations of the device are presented as follows: 1) single piece head mountable; 2) single piece back mountable; and 3) two piece back mountable. The device can be easily carried by the animal during the course of a clinical trial, and that it can produce non-stop stimulation current pulses of desired characteristics for over 12 days on a single battery. It employs passive charge balancing to minimize undesirable effects on the target tissue. The results of bench, in-vitro, and in-vivo tests to evaluate the performance of the device are presented.

SaBer DBS: a fully programmable, rechargeable, bilateral, charge-balanced preclinical microstimulator for long-term neural stimulation

To effectively study the mechanisms by which deep brain stimulation (DBS) produces its therapeutic benefit and to evaluate new therapeutic indications, it is vital to administer DBS over an extended period of time in awake, freely behaving animals. To date multiple preclinical stimulators have been designed and described. However, these stimulators have failed to incorporate some of the design criteria necessary to provide a system analogous to those used clinically. Here we define these design criteria and propose an improved and complete preclinical DBS system. This system is fully programmable in frequency, pulse-width and current amplitude, has a rechargeable battery and delivers biphasic, charge-balanced output to two independent electrodes. The system has been optimized for either implantation or for use externally via attachment to rodent jackets.