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Broncel A, Bocian R, Konopacki J. Vagal Nerve Stimulation: The Effect on the Brain Oscillatory Field Potential. Neuroscience 2021; 483:127-138. [PMID: 34952159 DOI: 10.1016/j.neuroscience.2021.12.023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2021] [Revised: 12/03/2021] [Accepted: 12/15/2021] [Indexed: 10/19/2022]
Abstract
More than thirty years of medical treatment with the use of vagal nerve stimulation (VNS) has shown that this therapeutic procedure works in a number of homeostatic disturbances. Although the clinical usage of VNS has a long history, our knowledge about the central mechanisms underlying this treatment is still limited. In the present paper we review the effects of VNS on brain oscillations as a possible electrophysiological bio-marker of VNS efficacy. The review was prepared mainly on the basis of data delivered from clinical observations and the outcomes of electrophysiological experiments conducted on laboratory animals that are available in PubMed. We consciously did not focus on epileptiform activity understood as a pathologic oscillatory activity, which was widely discussed in the numerous previously published reviews. The main conclusion of the present paper is that further, well-designed experiments on laboratory animals are absolutely necessary to address the electrophysiological issues. These will fill a number of gaps in our present knowledge of the central mechanisms underlying VNS therapy.
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Affiliation(s)
- Adam Broncel
- Medical Technology Centre, Natolin 15, 92-701 Lodz, Poland.
| | - Renata Bocian
- Department of Neurobiology, Faculty of Biology and Environmental Protection, The University of Lodz, Pomorska St. No. 141/143, 90-236 Lodz, Poland.
| | - Jan Konopacki
- Department of Neurobiology, Faculty of Biology and Environmental Protection, The University of Lodz, Pomorska St. No. 141/143, 90-236 Lodz, Poland.
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Chaves TC, Stanton TR, Grant A, Pulling BW, Madden VJ, Newport R, Moseley GL. Imprecise Visual Feedback About Hand Location Increases a Classically Conditioned Pain Expectancy Effect. THE JOURNAL OF PAIN 2021; 22:748-761. [PMID: 33529708 DOI: 10.1016/j.jpain.2021.01.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/14/2020] [Revised: 11/27/2020] [Accepted: 01/03/2021] [Indexed: 11/27/2022]
Abstract
We tested the hypotheses that rendering sensory input about hand location imprecise increases a classically conditioned pain expectancy effect, increases generalization of the effect to novel locations and reduces extinction of the effect. Forty healthy volunteers performed movements with their right hand along predefined paths. Each path passed through 2 locations that were defined as either i) the conditioned stimulus (CS+; paired with a painful unconditioned stimulus), or ii) unpaired (CS-). During acquisition phase, participants watched their hand as they moved it. Participants were randomly allocated to an Imprecise group, for whom visual feedback of the hand was offset 30 to 50 mm from its true location, or a Precise group, for whom vision was not disrupted. In the test phase, participants moved their hands to 5 locations-the CS+, CS-, and 3 locations that lay between the 2 ("generalization stimuli"). Our primary hypothesis was supported-pain expectancy was greater at the CS+ location in the Imprecise group than in the Precise group (6.9 [SD = 1.9] vs 5.4 [SD = 2.5], P= .02). Pain expectancies generalized to novel locations similarly in both groups and there was no difference in extinction between groups. Our primary hypothesis was supported but our subsequent hypotheses were not. PERSPECTIVE: We conditioned pain expectancy at a certain location of one hand, even though most participants were unaware of the contingency. Conditioned pain expectancy was greater when sensory information about location was less precise. This adds support to the possibility that associative learning may play a role in the progression of an acute pain episode to a more generalized pain disorder.
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Affiliation(s)
- Thais Cristina Chaves
- IIMPACT in Health, University of South Australia, Adelaide, Australia; Department of Health Sciences, Ribeirão Preto Medical School, University of São Paulo - USP, Ribeirão Preto, SP, Brazil; Department of Physical Therapy, Federal University of São Carlos, São Carlos, Brazil.
| | - Tasha R Stanton
- IIMPACT in Health, University of South Australia, Adelaide, Australia
| | - Ashley Grant
- IIMPACT in Health, University of South Australia, Adelaide, Australia
| | - Brian W Pulling
- IIMPACT in Health, University of South Australia, Adelaide, Australia
| | - Victoria J Madden
- IIMPACT in Health, University of South Australia, Adelaide, Australia; Department of Anaesthesia and Perioperative Medicine and Department of Psychiatry and Mental Health, Neuroscience Institute, University of Cape Town, Cape Town, South Africa
| | - Roger Newport
- School of Psychology, University of Nottingham, Nottingham, UK; School of Sport, Exercise and Health Sciences, Loughborough University, Leicestershire, UK
| | - G Lorimer Moseley
- IIMPACT in Health, University of South Australia, Adelaide, Australia
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Tigerholm J, Hoberg TN, Brønnum D, Vittinghus M, Frahm KS, Mørch CD. Small and large cutaneous fibers display different excitability properties to slowly increasing ramp pulses. J Neurophysiol 2020; 124:883-894. [PMID: 32783585 DOI: 10.1152/jn.00629.2019] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
The excitability of large nerve fibers is reduced when their membrane potential is slowly depolarizing, i.e., the fibers display accommodation. The aim of this study was to assess accommodation in small (mainly Aδ) and large (Aβ) cutaneous sensory nerve fibers using the perception threshold tracking (PTT) technique. Linearly increasing ramp currents (1 ms-200 ms) were used to assess the excitability of the nerve fibers by cutaneous electrical stimulation. To investigate the PPT technique's ability to preferentially activate different fiber types, topical application of lidocaine/prilocaine (EMLA) or a placebo cream was applied. By means of computational modeling, the underlying mechanisms governing the perception threshold in the two fiber types was studied. The axon models included the voltage-gated ion channels: transient TTX-sensitive sodium current, transient TTX-resistant sodium current (NaTTXr), persistent sodium current, delayed rectifier potassium channel (KDr), slow potassium channel, and hyperpolarization-activated current. Large fibers displayed accommodation, whereas small fibers did not display accommodation (P < 0.05). For the pin electrode, a significant interaction was observed between cream (EMLA or placebo) and pulse duration (P < 0.05); for the patch electrode, there was no significant interaction between cream and duration, which supports the pin electrode's preferential activation of small fibers. The results from the computational model suggested that differences in accommodation between the two fiber types may originate from selective expression of voltage-gated ion channels, particularly the transient NaTTXr and/or KDr. The PTT technique could assess the excitability changes during accommodation in different nerve fibers. Therefore, the PTT technique may be a useful tool for studying excitability in nerve fibers in both healthy and pathological conditions.NEW & NOTEWORTHY When large nerve fibers are stimulated by long, slowly increasing electrical pulses, interactive mechanisms counteract the stimulation, which is called accommodation. The perception threshold tracking technique was able to assess accommodation in both small and large fibers. The novelty of this study is that large fibers displayed accommodation, whereas small fibers did not. Additionally, the difference in accommodation between the fiber could be linked to expression of voltage-gated ion channels by means of computational modeling.
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Affiliation(s)
- Jenny Tigerholm
- Integrative Neuroscience Group, Center for Neuroplasticity and Pain (CNAP), Department of Health Science and Technology, Aalborg University, Aalborg, Denmark
| | - Tatiana Nielson Hoberg
- Center for Sensory-Motor Interaction (SMI), Department of Health Science and Technology, Aalborg University, Aalborg, Denmark
| | - Dorthe Brønnum
- Center for Sensory-Motor Interaction (SMI), Department of Health Science and Technology, Aalborg University, Aalborg, Denmark.,Centre for Clinical Research, North Denmark Regional Hospital, Hjørring, Denmark
| | - Mette Vittinghus
- Center for Sensory-Motor Interaction (SMI), Department of Health Science and Technology, Aalborg University, Aalborg, Denmark.,It-center for Telemedicin, Region Midtjylland, Aarhus N, Denmark
| | - Ken Steffen Frahm
- Center for Sensory-Motor Interaction (SMI), Department of Health Science and Technology, Aalborg University, Aalborg, Denmark.,Integrative Neuroscience Group, Center for Neuroplasticity and Pain (CNAP), Department of Health Science and Technology, Aalborg University, Aalborg, Denmark
| | - Carsten Dahl Mørch
- Center for Sensory-Motor Interaction (SMI), Department of Health Science and Technology, Aalborg University, Aalborg, Denmark.,Integrative Neuroscience Group, Center for Neuroplasticity and Pain (CNAP), Department of Health Science and Technology, Aalborg University, Aalborg, Denmark
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Hugosdottir R, Mørch CD, Andersen OK, Arendt-Nielsen L. Investigating stimulation parameters for preferential small-fiber activation using exponentially rising electrical currents. J Neurophysiol 2019; 122:1745-1752. [PMID: 31461369 DOI: 10.1152/jn.00390.2019] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Electrical stimulation is widely used in pain research and profiling, but current technologies lack selectivity toward small sensory fibers. Pin electrodes deliver high current density in upper skin layers, and it has been proposed that slowly rising exponential pulses can elevate large-fiber activation threshold and thereby increase preferential small-fiber activation. Optimal stimulation parameters for the combined pin electrode and exponential pulse stimulation have so far not been established, which is the aim of this study. Perception thresholds were compared between pin and patch electrodes using single 1- to 100-ms exponential and rectangular pulses. Stimulus-response functions were evaluated for both pulse shapes delivered as single pulses and pulse trains of 10 Hz using intensities from 0.1 to 20 times perception threshold. Perception thresholds (mA) decreased when duration was increased for both electrodes with rectangular pulses and the pin electrode with exponential pulses. For the patch electrode, perception thresholds for exponential pulses decreased for durations ≤10 ms but increased for durations ≥15 ms, indicating accommodation of large fibers. Stimulus-response curves for single pulses were similar for the two pulse shapes. For pulse trains, the slope of the curve was higher for rectangular pulses. Maximal large-fiber accommodation to exponential pulses was observed for 100-ms pulses, indicating that 100-ms exponential pulses should be applied for preferential small-fiber activation. Intensity of 10 times perception threshold was sufficient to cause maximal pain ratings. The developed methodology may open new opportunities for using electrical stimulation paradigms for small-fiber stimulation and diagnostics.NEW & NOTEWORTHY Selective activation of small cutaneous nerve fibers is pivotal for investigations of the pain system. The present study demonstrated that patch electrode perception thresholds increase with increased duration of exponential currents from 20 to 100 ms. This is likely caused by large-fiber accommodation, which can be utilized to activate small fibers preferentially through small-diameter pin electrodes. This finding may be utilized in studies of fundamental pain mechanisms and, for example, in small-fiber neuropathy.
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Affiliation(s)
- Rosa Hugosdottir
- Center of Neuroplasticity and Pain, SMI, Department of Health Science and Technology, Aalborg University, Aalborg, Denmark
| | - Carsten Dahl Mørch
- Center of Neuroplasticity and Pain, SMI, Department of Health Science and Technology, Aalborg University, Aalborg, Denmark
| | - Ole Kæseler Andersen
- Center of Neuroplasticity and Pain, SMI, Department of Health Science and Technology, Aalborg University, Aalborg, Denmark
| | - Lars Arendt-Nielsen
- Center of Neuroplasticity and Pain, SMI, Department of Health Science and Technology, Aalborg University, Aalborg, Denmark
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Sleutjes BTHM, Kovalchuk MO, Durmus N, Buitenweg JR, van Putten MJAM, van den Berg LH, Franssen H. Simulating perinodal changes observed in immune-mediated neuropathies: impact on conduction in a model of myelinated motor and sensory axons. J Neurophysiol 2019; 122:1036-1049. [PMID: 31291151 DOI: 10.1152/jn.00326.2019] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Immune-mediated neuropathies affect myelinated axons, resulting in conduction slowing or block that may affect motor and sensory axons differently. The underlying mechanisms of these neuropathies are not well understood. Using a myelinated axon model, we studied the impact of perinodal changes on conduction. We extended a longitudinal axon model (41 nodes of Ranvier) with biophysical properties unique to human myelinated motor and sensory axons. We simulated effects of temperature and axonal diameter on conduction and strength-duration properties. We then studied effects of impaired nodal sodium channel conductance and paranodal myelin detachment by reducing periaxonal resistance, as well as their interaction, on conduction in the 9 middle nodes and enclosed paranodes. Finally, we assessed the impact of reducing the affected region (5 nodes) and adding nodal widening. Physiological motor and sensory conduction velocities and changes to axonal diameter and temperature were observed. The sensory axon had a longer strength-duration time constant. Reducing sodium channel conductance and paranodal periaxonal resistance induced progressive conduction slowing. In motor axons, conduction block occurred with a 4-fold drop in sodium channel conductance or a 7.7-fold drop in periaxonal resistance. In sensory axons, block arose with a 4.8-fold drop in sodium channel conductance or a 9-fold drop in periaxonal resistance. This indicated that motor axons are more vulnerable to developing block. A boundary of block emerged when the two mechanisms interacted. This boundary shifted in opposite directions for a smaller affected region and nodal widening. These differences may contribute to the predominance of motor deficits observed in some immune-mediated neuropathies.NEW & NOTEWORTHY Immune-mediated neuropathies may affect myelinated motor and sensory axons differently. By the development of a computational model, we quantitatively studied the impact of perinodal changes on conduction in motor and sensory axons. Simulations of increasing nodal sodium channel dysfunction and paranodal myelin detachment induced progressive conduction slowing. Sensory axons were more resistant to block than motor axons. This could explain the greater predisposition of motor axons to functional deficits observed in some immune-mediated neuropathies.
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Affiliation(s)
- Boudewijn T H M Sleutjes
- Department of Neurology, Brain Center Utrecht, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Maria O Kovalchuk
- Department of Neurology, Brain Center Utrecht, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Naric Durmus
- Biomedical Signals and Systems, MIRA, Institute for Biomedical Technology and Technical Medicine, University of Twente, Enschede, The Netherlands.,Department of Clinical Neurophysiology, University of Twente, Enschede, The Netherlands
| | - Jan R Buitenweg
- Biomedical Signals and Systems, MIRA, Institute for Biomedical Technology and Technical Medicine, University of Twente, Enschede, The Netherlands
| | - Michel J A M van Putten
- Department of Clinical Neurophysiology, University of Twente, Enschede, The Netherlands.,Department of Neurology and Clinical Neurophysiology, Medisch Spectrum Twente, Enschede, The Netherlands
| | - Leonard H van den Berg
- Department of Neurology, Brain Center Utrecht, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Hessel Franssen
- Department of Neurology, Brain Center Utrecht, University Medical Center Utrecht, Utrecht, The Netherlands
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Azevedo DDP, Medeiros WM, de Freitas FFM, Ferreira Amorim C, Gimenes ACO, Neder JA, Chiavegato LD. High oxygen extraction and slow recovery of muscle deoxygenation kinetics after neuromuscular electrical stimulation in COPD patients. Eur J Appl Physiol 2016; 116:1899-910. [PMID: 27468840 DOI: 10.1007/s00421-016-3442-7] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2015] [Accepted: 07/22/2016] [Indexed: 11/27/2022]
Abstract
PURPOSE It was hypothesized that patients with chronic obstructive pulmonary disease (COPD) would exhibit a slow muscle deoxygenation (HHb) recovery time when compared with sedentary controls. METHODS Neuromuscular electrical stimulation (NMES 40 and 50 mA, 50 Hz, 400 µs) was employed to induce isometric contraction of the quadriceps. Microvascular oxygen extraction (µO2EF) and HHb were estimated by near-infrared spectroscopy (NIRS). Recovery kinetic was characterized by measuring the time constant Tau (HHb-τ). Torque and work were measured by isokinetic dynamometry in 13 non-hypoxaemic patients with moderate-to-severe COPD [SpO2 = 94.1 ± 1.6 %; FEV1 (% predict) 48.0 ± 9.6; GOLD II-III] and 13 age- and sex-matched sedentary controls. RESULTS There was no desaturation in either group during NMES. Torque and work were reduced in COPD versus control for 40 and 50 mA [torque (Nm) 50 mA = 28.9 ± 6.9 vs 46.1 ± 14.2; work (J) 50 mA = 437.2 ± 130.0 vs. 608.3 ± 136.8; P < 0.05 for all]. High µO2EF values were observed in the COPD group at both NMES intensities (corrected by muscle mass 50 mA = 6.18 ± 1.1 vs. 4.68 ± 1.0 %/kg; corrected by work 50 mA = 0.12 ± 0.05 vs. 0.07 ± 0.02 %/J; P < 0.05 for all). Absolute values of HHb-τ (50 mA = 31.11 ± 9.27 vs. 18.08 ± 10.70 s), corrected for muscle mass (50 mA 3.80 ± 1.28 vs. 2.05 ± 1.45 s/kg) and corrected for work (50 mA = 0.08 ± 0.04 vs. 0.03 ± 0.02 s/J) were reduced in COPD (P < 0.05 for all). The variables behaviour for 40 mA was similar to those of 50 mA. CONCLUSIONS COPD patients exhibited a slower muscle deoxygenation recovery time after NMES. The absence of desaturation, low torque and work, high µO2EF and high values for recovery time corrected by muscle mass and work suggest that intrinsic muscle dysfunction has an impact on muscle recovery capacity.
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Affiliation(s)
- Diego de Paiva Azevedo
- Master's and Doctoral Program in Physical Therapy, Universidade de São Paulo (UNICID), Sao Paulo, SP, Brazil
| | - Wladimir Musetti Medeiros
- Pulmonary Function and Clinical Exercise Physiology Unit, Division of Respiratory Medicine, Federal University of Sao Paulo (UNIFESP), Rua Professor Francisco de Castro 54, Vila Clementino, Sao Paulo, CEP 04020-050, Brazil
| | | | - Cesar Ferreira Amorim
- Master's and Doctoral Program in Physical Therapy, Universidade de São Paulo (UNICID), Sao Paulo, SP, Brazil
| | - Ana Cristina Oliveira Gimenes
- Pulmonary Function and Clinical Exercise Physiology Unit, Division of Respiratory Medicine, Federal University of Sao Paulo (UNIFESP), Rua Professor Francisco de Castro 54, Vila Clementino, Sao Paulo, CEP 04020-050, Brazil
| | - Jose Alberto Neder
- Pulmonary Function and Clinical Exercise Physiology Unit, Division of Respiratory Medicine, Federal University of Sao Paulo (UNIFESP), Rua Professor Francisco de Castro 54, Vila Clementino, Sao Paulo, CEP 04020-050, Brazil
| | - Luciana Dias Chiavegato
- Master's and Doctoral Program in Physical Therapy, Universidade de São Paulo (UNICID), Sao Paulo, SP, Brazil. .,Pulmonary Function and Clinical Exercise Physiology Unit, Division of Respiratory Medicine, Federal University of Sao Paulo (UNIFESP), Rua Professor Francisco de Castro 54, Vila Clementino, Sao Paulo, CEP 04020-050, Brazil.
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Brazhe AR, Maksimov GV, Mosekilde E, Sosnovtseva OV. Excitation block in a nerve fibre model owing to potassium-dependent changes in myelin resistance. Interface Focus 2010; 1:86-100. [PMID: 22419976 DOI: 10.1098/rsfs.2010.0001] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2010] [Accepted: 11/05/2010] [Indexed: 01/01/2023] Open
Abstract
The myelinated nerve fibre is formed by an axon and Schwann cells or oligodendrocytes that sheath the axon by winding around it in tight myelin layers. Repetitive stimulation of a fibre is known to result in accumulation of extracellular potassium ions, especially between the axon and the myelin. Uptake of potassium leads to Schwann cell swelling and myelin restructuring that impacts the electrical properties of the myelin. In order to further understand the dynamic interaction that takes place between the myelin and the axon, we have modelled submyelin potassium accumulation and related changes in myelin resistance during prolonged high-frequency stimulation. We predict that potassium-mediated decrease in myelin resistance leads to a functional excitation block with various patterns of altered spike trains. The patterns are found to depend on stimulation frequency and amplitude and to range from no block (less than 100 Hz) to a complete block (greater than 500 Hz). The transitional patterns include intermittent periodic block with interleaved spiking and non-spiking intervals of different relative duration as well as an unstable regime with chaotic switching between the spiking and non-spiking states. Intermittent conduction blocks are accompanied by oscillations of extracellular potassium. The mechanism of conductance block based on myelin restructuring complements the already known and modelled block via hyperpolarization mediated by the axonal sodium pump and potassium depolarization.
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Affiliation(s)
- A R Brazhe
- Biophysics Department, Biology Faculty, Moscow State University, Russia
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Subthreshold oscillations facilitate neuropathic spike discharge by overcoming membrane accommodation. Exp Neurol 2008; 210:194-206. [DOI: 10.1016/j.expneurol.2007.10.018] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2007] [Revised: 10/22/2007] [Accepted: 10/26/2007] [Indexed: 12/24/2022]
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