Deep brain stimulation.

Department of Neurology, Washington University School of Medicine, Washington University, St. Louis, Missouri 63110, USA.
Annual Review of Neuroscience (Impact Factor: 22.66). 02/2006; 29:229-57. DOI: 10.1146/annurev.neuro.29.051605.112824
Source: PubMed

ABSTRACT Deep brain stimulation (DBS) has provided remarkable benefits for people with a variety of neurologic conditions. Stimulation of the ventral intermediate nucleus of the thalamus can dramatically relieve tremor associated with essential tremor or Parkinson disease (PD). Similarly, stimulation of the subthalamic nucleus or the internal segment of the globus pallidus can substantially reduce bradykinesia, rigidity, tremor, and gait difficulties in people with PD. Multiple groups are attempting to extend this mode of treatment to other conditions. Yet, the precise mechanism of action of DBS remains uncertain. Such studies have importance that extends beyond clinical therapeutics. Investigations of the mechanisms of action of DBS have the potential to clarify fundamental issues such as the functional anatomy of selected brain circuits and the relationship between activity in those circuits and behavior. Although we review relevant clinical issues, we emphasize the importance of current and future investigations on these topics.

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    ABSTRACT: To understand how deep brain stimulation of the midbrain influences control of the urinary bladder. In urethane-anaesthetized male rats saline was infused continuously into the bladder to evoke cycles of filling and voiding. The effect of electrical (0.1-2.0ms pulses, 5-180Hz, 0.5-2.5V) compared to chemical stimulation (microinjection of D,L-homocysteic acid, 50nl 0.lM solution) at the same midbrain sites was tested. Electrical stimulation of the periaqueductal grey matter and surrounding midbrain disrupted normal co-ordinated voiding activity in detrusor and sphincters muscles and suppressed urine output. The effect occurred within seconds, was reversible and not secondary to cardiorespiratory changes. Bladder compliance remained unchanged. Chemical stimulation over the same area using microinjection of DLH to preferentially activate somatodendritic receptors decreased the frequency of micturition but did not disrupt the co-ordinated pattern of voiding. In contrast, chemical stimulation within the caudal ventrolateral periaqueductal grey, in the area where critical synapses in the micturition reflex pathway are located, increased the frequency of micturition. Electrical deep brain stimulation within the midbrain can inhibit reflex micturition. We suggest that the applied stimulus entrained activity in the neural circuitry locally, thereby imposing an unphysiological pattern of activity. In a way similar to the use of electrical signals to 'jam' radio transmission, this may prevent a synchronised pattern of efferent activity being transmitted to the spinal outflows to orchestrate a co-ordinated voiding response. Further experiments to record neuronal firing in the midbrain during the deep brain stimulation will be necessary to test this hypothesis. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.
    Acta Physiologica 03/2015; 214(1). DOI:10.1111/apha.12491 · 4.25 Impact Factor
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    ABSTRACT: Transcranial Direct Current Stimulation (tDCS) is emerging as a versatile tool to affect brain function. While acute neurophysiological effects of stimulation are well understood, little is know about the long term effects. One hypothesis is that stimulation modulates ongoing neural activity which then translates into lasting effects via physiological plasticity. Here we used carbachol-induced gamma oscillations in hippocampal rat slices to establish whether prolonged constant current stimulation has a lasting effect on endogenous neural activity. During 10 minutes of stimulation, power and frequency of gamma oscillations, as well as multi-unit activity were modulated in a polarity specific manner. Remarkably, the effects on power and multi-unit activity persisted for more than 10 minutes after stimulation terminated. Using a computational model we propose that altered synaptic efficacy in excitatory and inhibitory pathways could be the source of these lasting effects. Future experimental studies using this novel in-vitro preparation may be able to confirm or refute the proposed hypothesis. Copyright © 2014, Journal of Neurophysiology.
    Journal of Neurophysiology 12/2014; 113(5):jn.00208.2014. DOI:10.1152/jn.00208.2014 · 3.04 Impact Factor
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    ABSTRACT: Traditional neuronal interfaces utilize metallic electrodes which in recent years have reached a plateau in terms of the ability to provide safe stimulation at high resolution or rather with high densities of microelectrodes with improved spatial selectivity. To achieve higher resolution it has become clear that reducing the size of electrodes is required to enable higher electrode counts from the implant device. The limitations of interfacing electrodes including low charge injection limits, mechanical mismatch and foreign body response can be addressed through the use of organic electrode coatings which typically provide a softer, more roughened surface to enable both improved charge transfer and lower mechanical mismatch with neural tissue. Coating electrodes with conductive polymers or carbon nanotubes offers a substantial increase in charge transfer area compared to conventional platinum electrodes. These organic conductors provide safe electrical stimulation of tissue while avoiding undesirable chemical reactions and cell damage. However, the mechanical properties of conductive polymers are not ideal, as they are quite brittle. Hydrogel polymers present a versatile coating option for electrodes as they can be chemically modified to provide a soft and conductive scaffold. However, the in vivo chronic inflammatory response of these conductive hydrogels remains unknown. A more recent approach proposes tissue engineering the electrode interface through the use of encapsulated neurons within hydrogel coatings. This approach may provide a method for activating tissue at the cellular scale, however, several technological challenges must be addressed to demonstrate feasibility of this innovative idea. The review focuses on the various organic coatings which have been investigated to improve neural interface electrodes.
    Frontiers in Neuroengineering 05/2014; 7:15. DOI:10.3389/fneng.2014.00015