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Laser evoked potentials

Francesca Pistoia, Simona Sacco, Janet Stewart, Marco Sarà, Antonio Carolei
The experience of pain in disorders of consciousness is still debated. Neuroimaging studies, using functional Magnetic Resonance Imaging (fMRI), Positron Emission Tomography (PET), multichannel electroencephalography (EEG) and laser-evoked potentials, suggest that the perception of pain increases with the level of consciousness. Brain activation in response to noxious stimuli has been observed in patients with unresponsive wakefulness syndrome (UWS), which is also referred to as a vegetative state (VS), as well as those in a minimally conscious state (MCS)...
October 8, 2016: Brain Sciences
Baris Isak, Hatice Tankisi, Birger Johnsen, Kirsten Pugdahl, Nanna Brix Finnerup, Anders Fuglsang-Frederiksen
OBJECTIVE: Mild involvement of sensory nerves has been reported in previous studies in ALS patients. In this study, we assessed sensory pathways in ALS patients using laser evoked potentials (LEPs) and somatosensory evoked potentials (SSEPs). METHODS: We recruited 18 ALS patients and 31 healthy subjects. Neodymium-doped yttrium aluminium perovskite (Nd:YAP)-laser was used to evoke LEPs in upper (UE) and lower (LE) extremities. N1 and N2P2 potentials were obtained from contralateral insular cortex (T3 or T4) and vertex (Cz), respectively...
October 2016: Clinical Neurophysiology: Official Journal of the International Federation of Clinical Neurophysiology
Shoko Nagata, Shiro Nakamura, Kiyomi Nakayama, Ayako Mochizuki, Matsuo Yamamoto, Tomio Inoue
Dendrites of masseter (jaw-closing) motoneurons (MMNs) are well developed and ramify extensively throughout the trigeminal motor nucleus and often extend into the adjacent reticular formation. It is possible that the dendrites have active properties, which are altered with the development of the orofacial musculoskeletal system. Thus, we examined the changes in somatic voltage responses evoked by photostimulation of the MMN dendrites by laser photolysis of caged glutamate from postnatal day (P) 2-5 and 9-12 rats...
August 24, 2016: Brain Research Bulletin
Melissa O'Brien, Brian E Cairns
Ingestion of monosodium glutamate (MSG) has been shown to cause headaches in healthy individuals and trigger migraine-like headaches in migraine sufferers. We combined immunohistochemistry, in vivo electrophysiology, and laser Doppler recordings of dural vasculature to investigate the effect of systemic administration of MSG on the trigeminovascular pathway. Immunohistochemical analysis confirmed the expression of NMDA receptors on nerve fibres innervating dural blood vessels and excitatory amino acid transporter 2 on dural blood vessels...
August 11, 2016: Neuroscience
Julia Brill, Joanna Mattis, Karl Deisseroth, John R Huguenard
Neocortical pyramidal cells (PYRs) receive synaptic inputs from many types of GABAergic interneurons. Connections between parvalbumin (PV)-positive, fast-spiking interneurons ("PV cells") and PYRs are characterized by perisomatic synapses and high-amplitude, short-latency IPSCs. Here, we present novel methods to study the functional influence of PV cells on layer 5 PYRs using optogenetics combined with laser-scanning photostimulation (LSPS). First, we examined the strength and spatial distribution of PV-to-PYR inputs...
July 2016: ENeuro
Chryssoula Staikou, Panagiotis Kokotis, Andreas Kyrozis, Demetrios Rallis, George Makrydakis, Dimitra Manoli, Nikolaos Karandreas, Elefterios Stamboulis, Christos Moschovos, Argyro Fassoulaki
OBJECTIVE: We investigated differences in pain perception between men and women of reproductive age by using Laser-Evoked Potentials (LEPs). DESIGN, SETTING, SUBJECTS: Forty-four right-handed healthy volunteers (19 males/25 females), aged 30-40 years were studied. A CO2 laser generated three series of 10 thermal pulses (4.5 W) on the radial aspect of the dorsum of the left hand. A recording montage for late LEPs was used, and the potentials of each series of stimuli were averaged to calculate mean latency and amplitude for each subject...
July 29, 2016: Pain Medicine: the Official Journal of the American Academy of Pain Medicine
J S Springer, P Karlsson, C S Madsen, B Johnsen, N B Finnerup, T S Jensen, L Nikolajsen
BACKGROUND: Persistent pain is frequent after thoracotomy, with a reported prevalence of up to 60%. It remains unclear why some patients develop pain, whereas others do not. We therefore examined patients with and without pain after thoracotomy to identify pathophysiological contributors to persistent pain. METHODS: Twenty patients with persistent pain, 12 patients without pain and 20 healthy controls underwent detailed functional and structural assessment including psychometric and neuropathic pain questionnaires, bedside examination for pinprick hyperalgesia and brush allodynia, quantitative sensory testing according to the protocol of the German Research Network on Neuropathic Pain, measurement of capsaicin-evoked flare response, intradermal nerve density as determined by skin biopsies and laser- and heat-evoked potentials...
July 28, 2016: European Journal of Pain: EJP
Costanza Pazzaglia, Elisa Testani, Rocco Giordano, Luca Padua, Massimiliano Valeriani
Increased pain perception due to the expectation to feel more pain is called nocebo effect. The present study aimed at investigating whether: (1) the mere expectation to feel more pain after the administration of an inert drug can affect the laser-pain rating and the laser-evoked potential (LEP) amplitude, and (2) the learning potentiates the nocebo effect. Eighteen healthy volunteers were told that an inert cream, applied on the right hand, would increase the laser pain and LEP amplitude to right hand stimulation...
October 1, 2016: Neuroscience
M Moayedi, G Di Stefano, M T Stubbs, B Djeugam, M Liang, G D Iannetti
Feature selection has been extensively studied in the context of goal-directed behavior, where it is heavily driven by top-down factors. A more primitive version of this function is the detection of bottom-up changes in stimulus features in the environment. Indeed, the nervous system is tuned to detect fast-rising, intense stimuli that are likely to reflect threats, such as nociceptive somatosensory stimuli. These stimuli elicit large brain potentials maximal at the scalp vertex. When elicited by nociceptive laser stimuli, these responses are labeled laser-evoked potentials (LEPs)...
May 2016: ENeuro
Jia Zhao, Xiaoli Guo, Xiaolei Xia, Weiwei Peng, Wuchao Wang, Shulin Li, Ya Zhang, Li Hu
Functional reorganization of the somatosensory system was widely observed in phantom limb pain patients. Whereas some studies demonstrated that the primary somatosensory cortex (S1) of the amputated limb was engaged with the regions around it, others showed that phantom limb pain was associated with preserved structure and functional organization in the former brain region. However, according to the law of use and disuse, the sensitivity of S1 of the amputated limb to pain-related context should be enhanced due to the adaptation to the long-lasting phantom limb pain experience...
July 2016: Pain Physician
Laurence Dangers, Louis Laviolette, Bény Charbit, Thomas Similowski, Capucine Morélot-Panzini
BACKGROUND: Dyspnoea is a distressing and debilitating symptom with a major impact on quality of life. Alleviation of dyspnoea therefore constitutes a major clinical challenge. When causative physiological disorders cannot be corrected ("persistent dyspnoea"), nonspecific treatment must be considered. Morphine alleviates dyspnoea but has numerous side-effects including ventilatory depression, which justifies looking for alternatives. Certain forms of dyspnoea involve C-fibres, and can be attenuated by C-fibres blockade...
August 2016: Pulmonary Pharmacology & Therapeutics
Lila Khennouf, Bodil Gesslein, Barbara Lykke Lind, Arn M J M van den Maagdenberg, Martin Lauritzen
OBJECTIVE: Familial hemiplegic migraine type 1 (FHM1) is a subtype of migraine with aura caused by a gain-of-function mutation in the pore-forming α1 subunit of CaV 2.1 (P/Q-type) calcium channels. However, the mechanisms underlying how the disease is brought about and the prolonged aura remain incompletely understood. METHODS: In the anesthetized FHM1 mouse model in vivo, we used two-photon microscopy to measure calcium changes in neurons and astrocytes during somatosensory stimulations and cortical spreading depression (CSD), the putative mechanism of the migraine aura...
August 2016: Annals of Neurology
Rickard Liljemalm, Tobias Nyberg
Temperatures above the normal physiological threshold may cause damage to cells and tissue. In this study, the response of a culture of dissociated cerebral cortex cells exposed to laser-induced temperature gradients was examined. The cellular response was evaluated using a fluorescent dye indicating metabolic activity. Furthermore, by using a finite element model of the heating during the pulsed laser application, threshold temperatures could be extracted for the cellular response at different laser pulse lengths...
September 2016: International Journal of Hyperthermia
Éva Borbély, Katalin Sándor, Adrienn Markovics, Ágnes Kemény, Erika Pintér, János Szolcsányi, John P Quinn, Jason J McDougall, Zsuzsanna Helyes
OBJECTIVE, DESIGN: Mast cell tryptase (MCT) is elevated in arthritic joints, but its direct effects are not known. Here, we investigated MCT-evoked acute inflammatory and nociceptive mechanisms with behavioural, in vivo imaging and immunological techniques. MATERIAL AND SUBJECTS: Neurogenic inflammation involving capsaicin-sensitive afferents, transient receptor potential vanilloid 1 receptor (TRPV1), substance P (SP), neurokinin A (NKA) and their NK1 tachykinin receptor were studied using gene-deleted mice compared to C57Bl/6 wildtypes (n = 5-8/group)...
September 2016: Inflammation Research: Official Journal of the European Histamine Research Society ... [et Al.]
Marina de Tommaso, Marianna Delussi, Katia Ricci, Anna Montemurno, Irene Carbone, Eleonora Vecchio
Onabotulintoxin A (BontA) is an efficacious preventive treatment for chronic migraine, though the specific mechanism of action is still under discussion. The study aims: (1) To evaluate pain processing modifications in chronic migraine patients (CM) under single BontA administration in pericranial muscles, by means of CO² Laser Evoked Potentials (LEPs) obtained by the stimulation of the skin over the right frontal and trapezius injection sites and hand dorsum, in a double blind placebo controlled crossover design...
2016: Toxins
Eleonora Vecchio, Katia Ricci, Anna Montemurno, Marianna Delussi, Sara Invitto, Marina de Tommaso
Migraine is characterized by an altered cortical excitability. Because transcranial direct current stimulation (tDCS) can change brain activity noninvasively, it is possible to hypothesize its efficacy in modulating pain in migraine. In this study, we compared the effects of tDCS of the left primary motor cortex (M1) and left dorsolateral prefrontal cortex (DLPFC) both on subjective pain and on evoked responses induced by laser stimulation (LEPs). Thirty-two patients and sixteen controls were randomized to receive sham stimulation and real tDCS with the anode centered over M1 or DLPFC...
July 28, 2016: Neuroscience Letters
Mária Dux, Éva Deák, Noémi Tassi, Péter Sántha, Gábor Jancsó
BACKGROUND: In the dura mater encephali a significant population of trigeminal afferents coexpress the nociceptive ion channel transient receptor potential vanilloid type 1 (TRPV1) receptor and calcitonin gene-related peptide (CGRP). Release of CGRP serves the central transmission of sensory information, initiates local tissue reactions and may also sensitize the nociceptive pathway. To reveal the possible activation of meningeal TRPV1 receptors by endogenously synthetized agonists, the effects of arachidonylethanolamide (anandamide) and N-arachidonoyl-dopamine (NADA) were studied on dural vascular reactions and meningeal CGRP release...
2016: Journal of Headache and Pain
A B Schmidt, D L Andrews, A Rohrbach, C Gohn-Kreuz, V N Shatokhin, V G Kiselev, J Hennig, D von Elverfeldt, J-B Hövener
The hyperpolarization of nuclear spins promises great advances in chemical analysis and medical diagnosis by substantially increasing the sensitivity of nuclear magnetic resonance (NMR). Current methods to produce a hyperpolarized sample, however, are arduous, time-consuming or costly and require elaborate equipment. Recently, a much simpler approach was introduced that holds the potential, if harnessed appropriately, to revolutionize the production of hyperpolarized spins. It was reported that high levels of hyperpolarization in nuclear spins can be created by irradiation with a laser beam carrying orbital angular momentum (twisted light)...
July 2016: Journal of Magnetic Resonance
Dimosthenis Mantopoulos, Peggy Bouzika, Athanassios Tsakris, Basil S Pawlyk, Michael A Sandberg, Joan W Miller, Joseph F Rizzo Iii, Demetrios G Vavvas, Dean M Cestari
PURPOSE: Anterior ischemic optic neuropathy (AION) is the most common cause of non-glaucomatous optic nerve head (ONH) injury among older adults. AION results from a sudden ischemic insult to the proximal portion of the optic nerve, typically leading to visual impairment. Here, we present an experimental model of photodynamically induced ONH injury that can be used to study neuroprotective modalities. METHODS: Intraperitoneal injection of mesoporphyrin IX was followed by photodynamic treatment of the ONH in one eye of Brown-Norway rats; the fellow eye received the reverse sequence as a sham control...
May 9, 2016: Current Eye Research
Yiheng Tu, Ao Tan, Yanru Bai, Yeung Sam Hung, Zhiguo Zhang
Pain is a highly subjective experience. Self-report is the gold standard for pain assessment in clinical practice, but it may not be available or reliable in some populations. Neuroimaging data, such as electroencephalography (EEG) and functional magnetic resonance imaging (fMRI), have the potential to be used to provide physiology-based and quantitative nociceptive pain assessment tools that complements self-report. However, existing neuroimaging-based nociceptive pain assessments only rely on the information in pain-evoked brain activities, but neglect the fact that the perceived intensity of pain is also encoded by ongoing brain activities prior to painful stimulation...
2016: Frontiers in Computational Neuroscience
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