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.
See complete bios of the authors in the full version of this article.
Dr. Kouzani is an Associate Professor with the School of Engineering, Deakin University. He has been involved in over 1.9 million research grants, and he has published over 200 refereed papers.
Professor Abulseoud is an Assistant Professor of psychiatry with Mayo Medical School, with clinical practice in mood disorders and teaching activities in psychopharmacology. He is involved in basic, clinical, and translational research.
Dr. Tye is an Assistant Professor of psychiatry and psychology, where she directs the Translational Neuroscience Laboratory, with a focus on developing valid preclinical models of treatment resistant depression and bipolar disorder for investigation of disease and therapeutic mechanisms.
Mr. Hosain is pursuing a Ph.D. degree with Deakin University, Victoria, Australia. His current research interests include development of devices, and antennas and their applications to biomedical engineering, particularly brain stimulation.
Mr. Berk is the Foundation Chair in psychiatry with Deakin University, Victoria, Australia. He leads the Barwon Psychiatric Research Unit as well as the Professorial Unit with The Geelong Clinic.
Kouzani et al. give a detailed description of five different deep brain stimulation (DBS) devices, including stimuli current, time and frequency, and some other features. The description gives us an understandable perspective of each DBS device. On page 3 the authors clearly describe the advantages and disadvantages of each DBS device.
The authors describe their circuit diagram; they use the passive charge balancing method, one of the most popular methods to reduce risks in implants (Sooksood, et al., 2007). I think it might be helpful for readers to learn more about their diagram: ATtyny24A is a small low-power consumption microcontroller that is ideal for DBS applications. The authors use idle mode to turn off all microcontroller functions, except CPU. The circuit logic is very simple and excellent for this 2-pin application, producing a PWM signal to control a LM334-based controlled current source and turning on an indicator LED.
The low weight DBS device is excellent for implantation in a rat’s head with dental cement as they say and also their battery bench tests demonstrate a long working time, more than the time they need. The in-vivo test realized by Dr. Abulseoud’s team was successful as we can see, but the detailed results will be published by Dr. Abulseoud’s team.
In conclusion, I can tell that this is a nice solution, using minimal tools in a microcontroller, enhancing the design with a driver transistor and passive charge balancing, and the most important part: turning off undesired functions to save power.
This article appeared in the 2013 issue of IEEE Journal of Translational Engineering in Health and Medicine.
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