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Synapses
Published in Nassir H. Sabah, Neuromuscular Fundamentals, 2020
Neuromodulation is broadly defined as the alteration of neuronal activity through application of a stimulating agent, which could be electrical or chemical. In the present context, the term neuromodulator refers to a chemical agent that affects neurons over a relatively large area of the brain or the spinal cord, mostly through G protein-coupled receptors. Neuromodulators could be neurotransmitters, such as norepinephrine, acetylcholine, dopamine, serotonin, and histamine released by certain groups of neurons but not reabsorbed by the presynaptic neuron – nor broken down. They may be released at nerve endings, as in slow chemical synapses, or they may be carried by the cerebrospinal fluid. Neuromodulators could also be hormones circulating through the blood, such as thyroid hormones, steroid hormones (such as androgen and estrogen), metabolic hormones (such as insulin), stress hormones (such as cortisol), sex hormones (such as testosterone), or neuropeptides such as adenosine or oxytocin.
Medical device implants for neuromodulation
Published in Ze Zhang, Mahmoud Rouabhia, Simon E. Moulton, Conductive Polymers, 2018
According to the North American Neuromodulation Society, neuromodulation is the “therapeutic alteration of (neural) activity either through stimulation or medication” delivered through implanted devices, such as an IPG for DBS or drug pumps. Neuromodulation may target the central or peripheral nervous systems, including the spinal cord, brain, or spinal nerves. Traditionally, therapeutic neuromodulation has treated chronic pain, movement disorders, epilepsy, gastrological disorders, and urological disorders (Lewis et al. 2016). Recently, neuromodulation has been studied for the treatment of traumatic spinal cord and brain injuries (Shin et al. 2014) and psychiatric disorders (Wichmann and Delong 2006). Neuromodulation may be applied or investigated by clinicians and researchers from a range of disciplines, including neurosurgery, neurology, neuroscience, psychiatry, physical therapy, and rehabilitation.
Screening and Pharmacological Management of Neuropathic Pain
Published in Suvardhan Kanchi, Rajasekhar Chokkareddy, Mashallah Rezakazemi, Smart Nanodevices for Point-of-Care Applications, 2022
Manu Sharma, Ranju Soni, Kakarla Raghava Reddy, Veera Sadhu, Raghavendra V. Kulkarni
Neuromodulation is a normal physiological process regulating the functioning of diverse populations of neurons. Neurotransmitters like dopamine, serotonin, acetylcholine, histamine, and nor-epinephrine are neuromodulators. They exhibit a modulatory effect on target areas such as decorrelation of spiking, an increase of firing rate, sharpening of spatial tuning curves, and maintenance of increased spiking during working memory. A neuromodulator that is not re-absorbed by pre-synaptic neurons or metabolized can spend a remarkable duration in cerebrospinal fluid and modulate the activity of other neurons like serotonin ad acetylcholine.
Neuromodulatory effect of repetitive transcranial magnetic stimulation pulses on functional motor performances of spastic cerebral palsy children
Published in Journal of Medical Engineering & Technology, 2018
Meena Gupta, Bablu Lal Rajak, Dinesh Bhatia, Arun Mukherjee
The emergence of neuromodulation as a new therapeutic tool towards treatment of neurological disorders is due to the paradigm change of the clinicians that is shifting from the drug-related medication to modulating the neural circuitry of the brain using new medical devices such as vagus nerve stimulation (VNS), repetitive Transcranial magnetic stimulation (rTMS) and deep brain stimulation (DBS) [1]. The era of neuromodulation began in the early 1960s with the use of DBS to resolve chronic and intractable pain and henceforth, further applications of new simulation devices for the same purpose are governed by the International Neuromodulation Society (INS). INS defines the therapeutic neuromodulation as “the alteration of nerve activity through targeted delivery of a stimulus, such as electrical stimulation or chemical agents, to specific neurological sites in the body”. Neuromodulation approaches range from non-invasive techniques such as rTMS to implanted devices, such as a spinal cord stimulation or a deep brain stimulation system. The most common neuromodulation treatment device is the spinal cord stimulation system for chronic neuropathic pain [2] and in addition to this, other neuromodulation treatments employed for different disorders include epilepsy, Parkinson’s disease, essential tremors, dystonia, etc. [3–5]. Since neuromodulation is used to treat and enhance the quality of life in individuals who suffer from severe chronic illness due to persistent pain, spasticity and movement disorders, thus, we applied rTMS for the treatment of cerebral palsy patients.
The future of neuromodulation: smart neuromodulation
Published in Expert Review of Medical Devices, 2021
Dirk De Ridder, Jarek Maciaczyk, Sven Vanneste
Therefore, a new non-medicated way to treat brain disorders is crucial. Interestingly, the methodology for this is already available, albeit in a rudimentary form. Indeed, more than 60 years ago, in 1952, Delgado described the implantation of electrodes into the brain to measure electrical brain activity as a diagnostic tool, and deep brain stimulation through the same electrodes as a possible treatment for mental disorders [15]. This was based on the clinically beneficial effects of psychosurgery, by making lesions in the brain, and the development of stereotaxy [16], through which very targeted small lesions could be made [17]. The described technique was adapted for movement disorders in 1963 by Bechtereva in Russia [18] and later, in 1987, by Benabid in the western world [19]. However, the last 50 years have been characterized by a relative stagnation, in the development of new technology for brain stimulation, in stark contrast to the exponential technological progress in consumer devices such as smartphones, personal computers, etc. The discrepancy between the highly advanced consumer devices and brain implantation devices demonstrates there is a very large margin for improvement. In summary, neuromodulation consists of an electrode that is placed in the brain, on the spinal cord or near a nerve and affects the offended nerves and support cells. The International Neuromodulation Society defines neuromodulation as the alteration of nerve activity through targeted delivery of a stimulus, such as electrical stimulation or chemical agents, to specific neurological sites in the body [20]. The battery and the software that controls the stimuli are contained in an internal pulse generator (IPG), an adapted and derivative of the classic cardiac pacemaker.
Mechanism of peripheral nerve modulation and recent applications
Published in International Journal of Optomechatronics, 2021
Heejae Shin, Minseok Kang, Sanghoon Lee
The PNS plays an important role in transmitting sensory information obtained from organs to the CNS and transmitting commands from the CNS to organs or muscles. Since it has better accessibility compared to the CNS, research is being actively conducted to apply various types of neuromodulation to a variety of fields such as bioelectronic medicine and advanced bionic limbs. Among them, electrical neuromodulation is a conventional approach and is widely used for neuromodulation. We introduced the basic stimulation principles and method for this electrical neuromodulation and reviewed studies using various electrode designs in the direction of increasing selectiveness while inflicting less damage to nerves. In addition, voltage sources and current sources were discussed as electrical energy sources with pros and cons. Also, we introduced TENG, which can generate charge-balanced biphasic current waveform autonomously through energy harvesting. At the same time, we introduced that optogenetic neuromodulation can control the inherent limitations of selectivity of this electrical neuromodulation, and performs higher selectivity compared to the electrical modulation by controlling (exciting, inhibiting) ion channels in units of neurons. Although it is still necessary to prove the stability and efficacy of chronic opsin injection, it has shown that it is possible to perform precise selective stimulation through various applications and also can be applied to smooth muscle cells as well as neurons. Finally, the concept and importance of a closed-loop system were discussed with an example of bionic limbs. This closed-loop system is required not only for advanced bionic limbs but also for bioelectronic medicine. Various neuromodulation methods, which are developing in various directions, are expected to eventually be applied to a device with excellent selectiveness and a closed-loop system that can replace a broken body system.