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Graeme-Drury TJ, Worthen SF, Maden M, Raphael JH, Khan S, Vreugdenhil M, Duarte RV. Contact Heat in Magnetoencephalography: A Systematic Review. Can J Neurol Sci 2024; 51:179-186. [PMID: 36803520 DOI: 10.1017/cjn.2023.25] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/23/2023]
Abstract
BACKGROUND Contact heat is commonly used in experimental research to evoke brain activity, most frequently acquired with electroencephalography (EEG). Although magnetoencephalography (MEG) improves spatial resolution, using some contact heat stimulators with MEG can present methodological challenges. This systematic review assesses studies that utilise contact heat in MEG, their findings and possible directions for further research. METHODS Eight electronic databases were searched for relevant studies, in addition to the selected papers' reference lists, citations and ConnectedPapers maps. Best practice recommendations for systematic reviews were followed. Papers met inclusion criteria if they used MEG to record brain activity in conjunction with contact heat, regardless of stimulator equipment or paradigm. RESULTS Of 646 search results, seven studies met the inclusion criteria. Studies demonstrated effective electromagnetic artefact removal from MEG data, the ability to elicit affective anticipation and differences in deep brain stimulation responders. We identify contact heat stimulus parameters that should be reported in publications to ensure comparisons between data outcomes are consistent. CONCLUSIONS Contact heat is a viable alternative to laser or electrical stimulation in experimental research, and methods exist to successfully mitigate any electromagnetic noise generated by PATHWAY CHEPS equipment - though there is a dearth of literature exploring the post-stimulus time window.
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Affiliation(s)
| | - Siân F Worthen
- Aston Institute of Health and Neurodevelopment, Birmingham, UK
| | - Michelle Maden
- Liverpool Reviews and Implementation Group; University of Liverpool, Liverpool, UK
| | - Jon H Raphael
- School of Health Sciences, Birmingham City University, Birmingham, UK
| | - Salim Khan
- School of Health Sciences, Birmingham City University, Birmingham, UK
| | | | - Rui V Duarte
- Liverpool Reviews and Implementation Group; University of Liverpool, Liverpool, UK
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Frahm KS, Gervasio S, Arguissain F, Mouraux A. Influence of skin type and laser wavelength on laser-evoked potentials. Eur J Pain 2023; 27:1226-1238. [PMID: 37358263 DOI: 10.1002/ejp.2152] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2023] [Revised: 05/03/2023] [Accepted: 06/08/2023] [Indexed: 06/27/2023]
Abstract
BACKGROUND Infrared laser stimulation is a valuable tool in pain research, its primary application being the recording of laser-evoked brain potentials (LEPs). Different types of laser stimulators, varying in their skin penetrance, are likely to have a large influence on the LEPs, when stimulating different skin types. The aim of this study was to investigate how LEPs depend on laser type and skin location. METHODS Two different laser stimulators (CO2 and Nd:YAP) were used to compare LEPs in healthy subjects. Stimuli were delivered to the hand dorsum and palm to investigate the effects of skin type on the evoked responses. Stimulus-evoked brain responses were recorded using EEG and perceived intensity ratings were recorded. Computational modelling was used to investigate the observed differences. RESULTS LEPs evoked by stimulation of the hairy skin were similar between CO2 and Nd:YAP stimulation. In contrast, LEPs elicited from the palm were markedly different and barely present for CO2 stimulation. There was a significant interaction between laser type and skin type (RM-ANOVA, p < 0.05) likely due to smaller CO2 LEPs in the palm. CO2 stimuli to the palm also elicited significantly lower perceived intensities. The computational model showed that the observed differences were explainable by the laser absorption characteristics and skin thickness affecting the temperature profile at the dermo-epidermal junction (DEJ). CONCLUSIONS This study shows that LEP elicitation depends on the combination of laser penetrance and skin type. Low penetrance stimuli, from a CO2 laser, elicited significantly lower LEPs and perceived intensities in the palm. SIGNIFICANCE This study showed that the elicitation of laser-evoked potentials in healthy humans greatly depends on the combination of laser stimulator type and skin type. It was shown that high penetrance laser stimuli are capable of eliciting responses in both hairy and glabrous skin, whereas low penetrance stimuli barely elicited responses from the glabrous skin. Computational modelling was used to demonstrate that the results could be fully explained by the combination of laser type and skin thickness.
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Affiliation(s)
- Ken Steffen Frahm
- Integrative Neuroscience Group, CNAP - Center for Neuroplasticity and Pain, SMI©, Department of Health Science & Technology, Aalborg University, Aalborg, Denmark
| | - Sabata Gervasio
- Neural Engineering and Neurophysiology Group, SMI©, Department of Health Science & Technology, Aalborg University, Aalborg, Denmark
| | - Federico Arguissain
- Integrative Neuroscience Group, CNAP - Center for Neuroplasticity and Pain, SMI©, Department of Health Science & Technology, Aalborg University, Aalborg, Denmark
| | - André Mouraux
- Université Catholique de Louvain, Institute of Neuroscience (IoNS), Faculty of Medicine, Bruxelles, Belgium
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High-speed heating of the skin using a contact thermode elicits brain responses comparable to CO 2 laser-evoked potentials. Clin Neurophysiol 2023; 146:1-9. [PMID: 36473333 DOI: 10.1016/j.clinph.2022.11.008] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2021] [Revised: 11/05/2022] [Accepted: 11/12/2022] [Indexed: 11/25/2022]
Abstract
OBJECTIVE To compare nociceptive event-related brain potentials elicited by a high-speed contact-thermode vs an infrared CO2 laser stimulator. METHODS Contact heat-evoked potentials (CHEPs) and CO2 laser-evoked potentials (LEPs) were recorded in healthy volunteers using a high-speed contact-thermode (>200 °C/s) and a temperature-controlled CO2 laser. In separate experiments, stimuli were matched in terms of target surface temperature (55 °C) and intensity of perception. A finite-element model of skin heat transfer was used to explain observed differences. RESULTS For 55 °C stimuli, CHEPs were reduced in amplitude and delayed in latency as compared to LEPs. For perceptually matched stimuli (CHEPs: 62 °C; LEPs: 55 °C), amplitudes were similar, but CHEPs latencies remained delayed. These differences could be explained by skin thermal inertia producing differences in the heating profile of contact vs radiant heat at the dermo-epidermal junction. CONCLUSIONS Provided that steep heating ramps are used, and that target temperature is matched at the dermo-epidermal junction, contact and radiant laser heat stimulation elicit responses of similar magnitude. CHEPs are delayed compared to LEPs. SIGNIFICANCE CHEPs could be used as an alternative to LEPs for the diagnosis of neuropathic pain. Dedicated normative values must be used to account for differences in skin thermal transfer.
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Rujoie A, Andersen OK, Frahm KS. A novel temperature-controlled laser system to uniformly activate cutaneous thermal receptors during movable thermal stimulation. J Neural Eng 2023; 20. [PMID: 36638531 DOI: 10.1088/1741-2552/acb2f9] [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: 09/06/2022] [Accepted: 01/13/2023] [Indexed: 01/15/2023]
Abstract
Objective. Laser stimulators have been widely used in pain studies to selectively activate Aδand C nociceptors without coactivation of mechanoreceptors. Temperature-controlled laser systems have been implemented with low-temperature variations during stimulations, however, these systems purely enabled stationary stimulation. This study aimed to implement, test and validate a new laser stimulation system that controls skin temperature by continuously adjusting laser output during stimulus movement to allow accurate investigation of tempo-spatial mechanisms in the nociceptive system.Approach. For validation, laser stimuli were delivered to the right forearm of eight healthy subjects using a diode laser. The laser beam was displaced across the skin to deliver a moving thermal stimulation to the skin surface. To test the function and feasibility of the system, different stimulation parameters were investigated involving two control modes (open-loop and closed-loop), three displacement velocities (5, 10 and 12 mm s-1), two intensities (high 46 °C and low 42 °C), two stimulus lengths (20 and 100 mm) and two directions (distal and proximal).Main results. During closed-loop control, the stimulation error and variation of stimulation temperatures were significantly smaller than during open-loop control. The standard deviation of stimulation temperatures increased significantly with stimulation intensity and displacement length.Significance. This study showed that more accurate, less variable laser stimulations were delivered to the skin using closed-loop control during a movable stimulus. The more uniform skin temperature during stimuli is likely to ensure a more uniform nociceptor activation.
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Affiliation(s)
- Ahmad Rujoie
- Integrative Neuroscience group, Center for Neuroplasticity and Pain (CNAP), Department of Health Science & Technology, Aalborg University, Aalborg, Denmark
| | - Ole Kæseler Andersen
- Integrative Neuroscience group, Center for Neuroplasticity and Pain (CNAP), Department of Health Science & Technology, Aalborg University, Aalborg, Denmark
| | - Ken Steffen Frahm
- Integrative Neuroscience group, Center for Neuroplasticity and Pain (CNAP), Department of Health Science & Technology, Aalborg University, Aalborg, Denmark
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Xerfan EMS, Sartor A, Samama M, Facina AS, Tomimori J, Andersen ML. Reproduction, skin aging, and sleep in middle-aged women. Clin Dermatol 2022; 40:813-819. [PMID: 34780897 DOI: 10.1016/j.clindermatol.2021.11.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
There is a growing trend for women to delay having children, with a significant number of women postponing motherhood until the third or fourth decade of life. At the same time, these middle-aged women may be more concerned about skin aging and use dermatologic procedures to delay or repair the effects of aging, environmental factors, and oxidative stress on the skin. It has been suggested that the use of skin cosmetics and procedures may play a role in the reproductive system, although their possible effects have not yet been clearly elucidated. Another crucial factor that needs to be raised in this context is poor sleep, which seems to have an important relationship with both reduced fertility and accelerated skin aging, especially when it is associated with greater oxidative stress and hormonal imbalance. This review discusses the important triad of sleep, dermatology, and reproduction, a subject that has received relatively little attention; and, given its potentially wide-ranging implications, one that deserves more frequent and detailed consideration in future studies. Understanding this complex web of interactions could help to provide outcomes that include healthier skin, safety, improved self-esteem, and successful fertility treatments, all of which can directly affect quality of life.
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Affiliation(s)
- Ellen M S Xerfan
- Programa de Pós-Graduação em Medicina Translacional, Departamento de Medicina, Escola Paulista de Medicina, Universidade Federal de São Paulo (UNIFESP), São Paulo, Brazil
| | - Amanda Sartor
- GERA Institute, São Paulo, Brazil; Department of Psychobiology, Escola Paulista de Medicina, Universidade Federal de São Paulo (UNIFESP), São Paulo, Brazil
| | - Marise Samama
- GERA Institute, São Paulo, Brazil; Department of Gynecology, Escola Paulista de Medicina, Universidade Federal de São Paulo (UNIFESP), São Paulo, Brazil
| | - Anamaria S Facina
- Department of Dermatology, Escola Paulista de Medicina, Universidade Federal de São Paulo (UNIFESP), São Paulo, Brazil
| | - Jane Tomimori
- Programa de Pós-Graduação em Medicina Translacional, Departamento de Medicina, Escola Paulista de Medicina, Universidade Federal de São Paulo (UNIFESP), São Paulo, Brazil; Department of Dermatology, Escola Paulista de Medicina, Universidade Federal de São Paulo (UNIFESP), São Paulo, Brazil
| | - Monica L Andersen
- Department of Psychobiology, Escola Paulista de Medicina, Universidade Federal de São Paulo (UNIFESP), São Paulo, Brazil.
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Courtin AS, Mouraux A. Combining Topical Agonists With the Recording of Event-Related Brain Potentials to Probe the Functional Involvement of TRPM8, TRPA1 and TRPV1 in Heat and Cold Transduction in the Human Skin. THE JOURNAL OF PAIN 2022; 23:754-771. [PMID: 34863944 DOI: 10.1016/j.jpain.2021.11.008] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/03/2021] [Revised: 11/04/2021] [Accepted: 11/18/2021] [Indexed: 06/13/2023]
Abstract
TRP channels play a central role in the transduction of thermal and nociceptive stimuli by free nerve endings. Most of the research on these channels has been conducted in vitro or in vivo in nonhuman animals and translation of these results to humans must account for potential experimental biases and interspecific differences. This study aimed at evaluating the involvement of TRPM8, TRPA1 and TRPV1 channels in the transduction of heat and cold stimuli by the human thermonociceptive system. For this purpose, we evaluated the effects of topical agonists of these 3 channels (menthol, cinnamaldehyde and capsaicin) on the event-related brain potentials (ERPs) elicited by phasic thermal stimuli (target temperatures: 10°C, 42°C, and 60°C) selected to activate cold Aδ thermoreceptors, warm sensitive C thermoreceptors and heat sensitive Aδ polymodal nociceptors. Sixty-four participants were recruited, 16 allocated to each agonist solution group (20% menthol, 10% cinnamaldehyde, .025% capsaicin and 1% capsaicin). Participants were treated sequentially with the active solution on one forearm and vehicle only on the other forearm for 20 minutes. Menthol decreased the amplitude and increased the latency of cold and heat ERPs. Cinnamic aldehyde decreased the amplitude and increased the latency of heat but not cold ERPs. Capsaicin decreased the amplitude and increased the latency of heat ERPs and decreased the amplitude of the N2P2 complex of the cold ERPs without affecting the earlier N1 wave or the latencies of the peaks. These findings are compatible with previous evidence indicating that TRPM8 is involved in innocuous cold transduction and that TRPV1 and TRPA1 are involved in noxious heat transduction in humans. PERSPECTIVE: By chemically modulating TRPM8, TRPA1 and TRPV1 reactivity (key molecules in the transduction of temperature) and assessing how this affected EEG responses to the activation of cold thermoreceptors and heat nociceptors, we aimed at confirming the role of these channels in a functional healthy human model.
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Affiliation(s)
- Arthur S Courtin
- Institute of NeuroScience, Université catholique de Louvain, Brussels, Belgium.
| | - André Mouraux
- Institute of NeuroScience, Université catholique de Louvain, Brussels, Belgium
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Improved acquisition of contact heat evoked potentials with increased heating ramp. Sci Rep 2022; 12:925. [PMID: 35042939 PMCID: PMC8766469 DOI: 10.1038/s41598-022-04867-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2021] [Accepted: 12/29/2021] [Indexed: 12/05/2022] Open
Abstract
Contact heat evoked potentials (CHEPs) represent an objective and non-invasive measure to investigate the integrity of the nociceptive neuraxis. The clinical value of CHEPs is mostly reflected in improved diagnosis of peripheral neuropathies and spinal lesions. One of the limitations of conventional contact heat stimulation is the relatively slow heating ramp (70 °C/s). This is thought to create a problem of desynchronized evoked responses in the brain, particularly after stimulation in the feet. Recent technological advancements allow for an increased heating ramp of contact heat stimulation, however, to what extent these improve the acquisition of evoked potentials is still unknown. In the current study, 30 healthy subjects were stimulated with contact heat at the hand and foot with four different heating ramps (i.e., 150 °C/s, 200 °C/s, 250 °C/s, and 300 °C/s) to a peak temperature of 60 °C. We examined changes in amplitude, latency, and signal-to-noise ratio (SNR) of the vertex (N2-P2) waveforms. Faster heating ramps decreased CHEP latency for hand and foot stimulation (hand: F = 18.41, p < 0.001; foot: F = 4.19, p = 0.009). Following stimulation of the foot only, faster heating ramps increased SNR (F = 3.32, p = 0.024) and N2 amplitude (F = 4.38, p = 0.007). Our findings suggest that clinical applications of CHEPs should consider adopting faster heating ramps up to 250 °C/s. The improved acquisition of CHEPs might consequently reduce false negative results in clinical cohorts. From a physiological perspective, our results demonstrate the importance of peripherally synchronizing afferents recruitment to satisfactorily acquire CHEPs.
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