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Pain Assessment Using Near-Infrared Spectroscopy
Published in Yu Chen, Babak Kateb, Neurophotonics and Brain Mapping, 2017
Kambiz Pourrezaei, Ahmad Pourshoghi, Zeinab Barati, Issa Zakeri
fMRI data has been used to decode whether a stimulus was perceived as painful (Brodersen et al., 2012). The results show that during pain anticipation, activity in the periaqueductal gray (PAG) and orbitofrontal cortex (OFC) afforded the most accurate trial-by-trial discrimination between painful and nonpainful experiences; whereas during the actual stimulation, primary and secondary somatosensory cortex, anterior insula, dorsolateral and ventrolateral prefrontal cortex, and OFC were most discriminative. The most accurate prediction of pain perception during the stimulation period, however, was made by a combined activity in the pain regions, commonly referred to as the “pain matrix,” a name given to an extensive network of brain regions activated during pain perception, including somatosensory, insular, and cingulate areas, as well as frontal and parietal areas.
The Modern Magnetotherapies
Published in Andrew A. Marino, Modern Bioelectricity, 2020
Another kind of special tissue involves the periventricular structures and circumventricular organs; the latter include the pineal organ, subfornical organ, subcommissural organ, and the area postrema. These structures have poor blood brain barriers and are highly localized vascular, neuronal, and cerebrospinal interfaces. Electrical stimulation of the periaqueductal gray has been reported several times to be associated with pain relief; there is now corroborative evidence that such stimulation elevates beta-endorphins within the ventricular fluid (46), Whether or not fine-focused magnetic fields can accomplish this stimulation or if magnetoresponsive patients have a particular sensitivity of these brain structures remains to be established.
B
Published in Splinter Robert, Illustrated Encyclopedia of Applied and Engineering Physics, 2017
[general] A branch of physics that integrates physics, biology, chemistry, and engineering to understand the workings of physiological phenomena as well as the mechanics of the anatomy and the operational mechanism of action for the various senses. The senses for animals may be different and supplemental to human senses: smell, taste, hearing, sight, touch, and pain (pain is considered a separate sense). Several animals can sense magnetic and electric fields, for instance, sharks for prey identification, and platypus for navigation, next to birds for their migratory path. The blood flow and corrections to flow by means of atherectomy or artificial heart replacement are a fluid dynamics aspect of biology that are critical for survival. The biological field stretches out from mechanics to fluid dynamics, thermodynamics, optics, and chemistry. In biology, most physical phenomena are not consistent between individuals and they change over time (compliance/time dependence). One specific note on pain: when a pain signal is processed in the somatosensory area of the parietal lobe of the brain, the location of the source for the pain is registered. Although pain originates from an internal organ, the source of pain may be elusive and misdirected. The action-potential activation of the insular cortex in the frontal lobe of the brain provides an immediate motivation to reverse the cause. In case the frontal lobe has areas that are damaged, one can feel the pain, but is not motivated to counteract it or remove from the source. The periaqueductal gray area of the brain (midbrain) has the ability to close down the pain gate, thus alleviating the sensation of pain by chemical means. Chemicals such as endorphins affect the periaqueductal gray area by increasing its gate-blocking activity. Endorphins are produced naturally in the brain. Similar externally produced analgesics, such as morphine, also affect the periaqueductal gray area. Additional endorphins can be produced by the pituitary and adrenal glands. These glands release hormones under the influence of external stimuli. One specific example is the phenomenon of stress-induced suppression of pain (analgesia).
Transcranial direct current stimulation combined with peripheral stimulation in chronic pain: a systematic review and meta-analysis
Published in Expert Review of Medical Devices, 2023
Rayssa Maria Do Nascimento, Rafael Limeira Cavalcanti, Clécio Gabriel Souza, Gabriela Chaves, Liane Brito Macedo
The combination of peripheral stimulation and transcranial stimulation could act priming the brain, that is, one therapy would increase the brain’s receptiveness to receive the other therapy. This occurs due to the capacity of these techniques to neuromodulate the cortex, increasing or decreasing its excitability [46]. Besides that, their top-down and bottom-up approaches could act together by bombarding the pain system and inducing a summative effect [45,47]. It is worth to remember that tDCS acts on motor cortex and its mechanisms for pain are related to neurophysiological changes, such as decrease in thalamic hyperactivity and neurochemical mediation of neurotransmitters and central receptors involved with the inhibitory control of descending pain pathways [48,49]. On the other hand, the most used forms of peripheral electrical stimulation for pain treatment, in theory, act through two main mechanisms: 1) selective stimulation of large-diameter non-nociceptive neural fibers at the level of spinal dorsal horn, activating inhibitory neurons of pain and suppressing nociceptive fibers (gait control theory of pain) [50,51] and 2) release of endogenous opioids and inhibition of nociceptive markers through activation of specific receptors in areas of pain control, such as rostral ventromedial medulla and periaqueductal gray [52,53].
Development and evaluation of acu-magnetic therapeutic knee brace for symptomatic knee osteoarthritis relief in the elderly
Published in The Journal of The Textile Institute, 2021
Zidan Gong, Rong Liu, Winnie Yu, Thomas Kwok-Shing Wong, Yuanqi Guo
Clinical evidence has showed that the acu-magnetic stimulation would increase regional blood circulation (Sorour et al., 2014) and cause neurohormonal responses and secretions (Moyer et al., 2011; Wong & Jun Shen, 2010). Ion channel could be activated, and the resultant concentrations of K+, Na+, Ca+ may change among the sensory neuron networks, causing hypothalamic pituitary adrenocortical axis activation (Deng et al., 1995). The neurotransmitters like endorphin and serotonin can be secreted by hypothalamus and pituitary gland to suppress pain perception, producing happiness, relaxation, as well as improving psychomotor balance [76–78]. The knee pain and acu-stimulation signals received by peripheral sensory nerve may further transmit to the brain through the paths in the spinal cord. Physiological studies (Stux & Hammerschlag, 2001; Wong & Jun Shen, 2010) indicated that acu-stimulations can activate the raphe nuclei in the periaqueductal gray matter, inducing descending inhibition signals down to the spinal cord where the knee pain signals first enter to, thus significantly weaken or block pain signals to relieve the pain sensation.
Burst and high frequency stimulation: underlying mechanism of action
Published in Expert Review of Medical Devices, 2018
Shaheen Ahmed, Thomas Yearwood, Dirk De Ridder, Sven Vanneste
At a systemic level, different pathways are responsible for processing different aspects of pain signals, as shown in Figure 2. A lateral pain system processes the discriminative components (location, intensity, and character) of the pain, mediated by the lateral thalamic nuclei and the somatosensory cortex. Concomitantly, a medial pain system involving the medial thalamic nuclei and the anterior cingulate cortex has been associated with the emotional and motivational aspects of pain, comprising such elements as the unpleasantness of the pain stimulus. In addition, a descending inhibition pain system involving the rostral and pregenual anterior cingulate cortices, with connections to the thalamus, the parahippocampal area, the periaqueductal gray, and the rostroventral part of the medulla oblongata. Imaging modalities such as functional magnetic resonance imaging demonstrate that tonic stimulation mainly modulates the lateral pain pathway, as visualized by blood-oxygen-level-dependent changes in the sensory thalamus and somatosensory cortices, but not in the dorsal anterior cingulate cortex or the insula [18]. A positron-emission tomography study further corroborated this hypothesis by demonstrating that activity increases in the thalamus contralateral to the painful limb as well as in the bilateral parietal association cortex, the anterior cingulate cortex, and prefrontal areas [19]. Hence, tonic stimulation only minimally modulates the medial pain system. Correlation analysis indicates that the amount of pain suppression is related to the activation of the pregenual anterior cingulate cortex and the dorsolateral prefrontal cortex, i.e. to the amount of mobilization of the descending pain inhibitory pathway [20].