| 1. |
- Birznieks, Ingvars, et al.
(författare)
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Tactile sensory channels over-ruled by frequency decoding system that utilizes spike pattern regardless of receptor type
- 2019
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Ingår i: eLIFE. - Cambridge, United Kingdom : ELIFE SCIENCES PUBLICATIONS LTD. - 2050-084X. ; 8
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Tidskriftsartikel (refereegranskat)abstract
- The established view is that vibrotactile stimuli evoke two qualitatively distinctive cutaneous sensations, flutter (frequencies amp;lt; 60 Hz) and vibratory hum (frequencies amp;gt; 60 Hz), subserved by two distinct receptor types (Meissners and Pacinian corpuscle, respectively), which may engage different neural processing pathways or channels and fulfil quite different biological roles. In psychological and physiological literature, those two systems have been labelled as Pacinian and non-Pacinian channels. However, we present evidence that low-frequency spike trains in Pacinian afferents can readily induce a vibratory percept with the same low frequency attributes as sinusoidal stimuli of the same frequency, thus demonstrating a universal frequency decoding system. We achieved this using brief low-amplitude pulsatile mechanical stimuli to selectively activate Pacinian afferents. This indicates that spiking pattern, regardless of receptor type, determines vibrotactile frequency perception. This mechanism may underlie the constancy of vibrotactile frequency perception across different skin regions innervated by distinct afferent types.
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| 2. |
- Böhme, Rebecca, et al.
(författare)
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Anhedonia to Gentle Touch in Fibromyalgia: Normal Sensory Processing but Abnormal Evaluation
- 2020
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Ingår i: Brain Sciences. - : MDPI. - 2076-3425. ; 10:5
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Tidskriftsartikel (refereegranskat)abstract
- Social touch is important for interpersonal interaction. Gentle touch and slow brushing are typically perceived as pleasant, the degree of pleasantness is linked to the activity of the C-tactile (CT) fibers, a class of unmyelinated nerves in the skin. The inability to experience pleasure in general is called anhedonia, a common phenomenon in the chronic pain condition fibromyalgia. Here, we studied the perception and cortical processing of gentle touch in a well-characterized cohort of fibromyalgia. Patients and controls participated in functional brain imaging while receiving tactile stimuli (brushing) on the forearm. They were asked to provide ratings of pleasantness of the tactile stimulus and ongoing pain. We found high distress, pain catastrophizing, and insomnia, and a low perceived state of health in fibromyalgia. Further, patients rated both slow (CT-optimal) and fast (CT-suboptimal) brushing as less pleasant than healthy participants. While there was no difference in brain activity during touch, patients showed deactivation in the right posterior insula (contralateral to the stimulated arm) during pleasantness rating and activation during pain rating. The opposite pattern was observed in healthy participants. Voxel-based morphometry analysis revealed reduced grey matter density in patients, in the bilateral hippocampus and anterior insula. Our results suggest anhedonia to gentle touch in fibromyalgia with intact early-stage sensory processing but dysfunctional evaluative processing. These findings contribute to our understanding of the mechanisms underlying anhedonia in fibromyalgia.
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| 3. |
- Dittrich, Christian, et al.
(författare)
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ESMO / ASCO Recommendations for a Global Curriculum in Medical Oncology Edition 2016
- 2016
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Ingår i: ESMO Open. - : Elsevier BV. - 2059-7029. ; 1:5
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Tidskriftsartikel (refereegranskat)abstract
- The European Society for Medical Oncology (ESMO) and the American Society of Clinical Oncology (ASCO) are publishing a new edition of the ESMO/ ASCO Global Curriculum (GC) thanks to contribution of 64 ESMOappointed and 32 ASCO-appointed authors. First published in 2004 and updated in 2010, the GC edition 2016 answers to the need for updated recommendations for the training of physicians in medical oncology by defining the standard to be fulfilled to qualify as medical oncologists. At times of internationalisation of healthcare and increased mobility of patients and physicians, the GC aims to provide state-of-the-art cancer care to all patients wherever they live. Recent progress in the field of cancer research has indeed resulted in diagnostic and therapeutic innovations such as targeted therapies as a standard therapeutic approach or personalised cancer medicine specialised training for medical oncology trainees. Thus, several new chapters on technical contents such as molecular pathology, translational research or molecular imaging and on conceptual attitudes towards human principles like genetic counselling or survivorship have been integrated in the GC. The GC edition 2016 consists of 12 sections with 17 subsections, 44 chapters and 35 subchapters, respectively. Besides renewal in its contents, the GC underwent a principal formal change taking into consideration modern didactic principles. It is presented in a template-based format that subcategorises the detailed outcome requirements into learning objectives, awareness, knowledge and skills. Consecutive steps will be those of harmonising and implementing teaching and assessment strategies.
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| 4. |
- Dunn, James S., et al.
(författare)
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Minocycline reduces experimental muscle hyperalgesia induced by repeated nerve growth factor injections in humans: A placebo-controlled double-blind drug-crossover study
- 2020
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Ingår i: European Journal of Pain. - : WILEY. - 1090-3801 .- 1532-2149. ; 24:6, s. 1138-1150
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Tidskriftsartikel (refereegranskat)abstract
- Background Hyperalgesia is a heightened pain response to a noxious stimulus and is a hallmark of many common neuropathic and chronic pain conditions. In a double-blind placebo-controlled drug-crossover trial, the effects of concomitant and delayed minocycline treatment on the initiation and resolution of muscle hyperalgesia were tested. Methods An initial cohort (n = 10) received repeated injections (5 mu g: days 0, 2 and 4) of nerve growth factor (NGF) in the flexor carpi ulnaris muscle of the forearm and pressure pain thresholds were collected at day 0 (control), day 7 (peak) and day 14 (recovery). A second cohort (n = 18) underwent an identical procedure, however, half received a placebo between days 0 and 7 before switching to minocycline from days 7 to 14 (P1/M2), while the remaining subjects received minocycline (day 0: 200mg then 100mg b.i.d. for 7 days) before switching to placebo (M1/P2). Results The initial cohort exhibited a diffuse muscular pain hypersensitivity with a decrease in pressure pain thresholds at day 7 before a partial return to normalcy at day 14. The P1/M2 treatment group exhibited an identical peak in hypersensitivity at day 7, however, after switching to minocycline in week 2 showed a significant reduction in muscle hyperalgesia compared with the initial cohort at day 14. The M1/P2 treatment group had significantly less (similar to 43%) hyperalgesia at day 7 compared with the other groups. Conclusions The study indicates that the administration of minocycline can reduce experimentally induced muscle pain regardless of the time of administration. Significance In a double-blind placebo-controlled drug-crossover study, the common antibiotic minocycline was found to reduce the muscle hyperalgesia induced by intramuscular injection of nerve growth factor. The results of the study showed that both concomitant (pre-emptive) and delayed administration of minocycline can ameliorate the onset and facilitate the resolution of experimentally induced muscle hyperalgesia.
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| 5. |
- Dunn, James S., et al.
(författare)
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Modulation of Muscle Pain Is Not Somatotopically Restricted: An Experimental Model Using Concurrent Hypertonic-Normal Saline Infusions in Humans
- 2020
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Ingår i: Frontiers in Pain Research. - : Frontiers Media SA. - 2673-561X. ; 1
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Tidskriftsartikel (refereegranskat)abstract
- We have previously shown that during muscle pain induced by infusion of hypertonic saline (HS), concurrent application of vibration and gentle brushing to overlying and adjacent skin regions increases the overall pain. In the current study, we focused on muscle-muscle interactions and tested whether HS-induced muscle pain can be modulated by innocuous/sub-perceptual stimulation of adjacent, contralateral, and remote muscles. Psychophysical observations were made in 23 healthy participants. HS (5%) was infused into a forearm muscle (flexor carpi ulnaris) to produce a stable baseline pain. In separate experiments, in each of the three test locations (n = 10 per site) - ipsilateral hand (abductor digiti minimi), contralateral forearm (flexor carpi ulnaris), and contralateral leg (tibialis anterior) - 50 μl of 0.9% normal saline (NS) was infused (in triplicate) before, during, and upon cessation of HS-induced muscle pain in the forearm. In the absence of background pain, the infusion of NS was imperceptible to all participants. In the presence of HS-induced pain in the forearm, the concurrent infusion of NS into the ipsilateral hand, contralateral forearm, and contralateral leg increased the overall pain by 16, 12, and 15%, respectively. These effects were significant, reproducible, and time-locked to NS infusions. Further, the NS-evoked increase in pain was almost always ascribed to the forearm where HS was infused with no discernible percept attributed to the sites of NS infusion. Based on these observations, we conclude that intramuscular infusion of HS results in muscle hyperalgesia to sub-perceptual stimulation of muscle afferents in a somatotopically unrestricted manner, indicating the involvement of a central (likely supra-spinal) mechanism.
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| 6. |
- Dunn, James S., et al.
(författare)
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Why does a cooled object feel heavier? Psychophysical investigations into the Webers Phenomenon
- 2017
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Ingår i: BMC Neuroscience. - : BIOMED CENTRAL LTD. - 1471-2202. ; 18
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Tidskriftsartikel (refereegranskat)abstract
- Background: It has long been known that a concomitantly cooled stimulus is perceived as heavier than the same object at a neutral temperature-termed Webers Phenomenon (WP). In the current study, we re-examined this phenomenon using well-controlled force and temperature stimuli to explore the complex interplay between thermal and tactile systems, and the peripheral substrates contributing to these interactions. A feedback-controlled apparatus was constructed using a mechanical stimulator attached to a 5- x 5-mm thermode. Force combinations of 0.5 and 1 N (superimposed on 1-N step) were applied to the ulnar territory of dorsal hand. One of the forces had a thermal component, being cooled from 32 to 28 degrees C at a rate of 2 degrees C/s with a 3-s static phase. The other stimulus was thermally neutral (32 degrees C). Participants were asked to report whether the first or the second stimulus was perceived heavier. These observations were obtained in the all-fibre-intact condition and following the preferential block of myelinated fibres by compression of ulnar nerve. Results: In normal condition, when the same forces were applied, all subjects displayed a clear preference for the cooled tactile stimulus as being heavier than the tactile-only stimulus. The frequency of this effect was augmented by an additional similar to 17% when cooling was applied concurrently with the second stimulus. Following compression block, the mean incidence of WP was significantly reduced regardless of whether cooling was applied concurrently with the first or the second stimulus. However, while the effect was abolished in case of former (elicited in amp;lt; 50% of trials), the compression block had little effect in four out of nine participants in case of latter who reported WP in at least 80% of trials (despite abolition of vibration and cold sensations). Conclusions: WP was found to be a robust tactile-thermal interaction in the all-fibre-intact condition. The emergence of inter-individual differences during myelinated block suggests that subjects may adopt strategies, unbeknownst to them, that focus on the dominant input (myelinated fibres, hence WP abolished by block) or the sum of convergent inputs (myelinated and C fibres, hence WP preserved during block) in order to determine differences in perceived heaviness.
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| 7. |
- Hauser, Steven C., et al.
(författare)
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From Human-to-Human Touch to Peripheral Nerve Responses
- 2019
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Ingår i: 2019 IEEE WORLD HAPTICS CONFERENCE (WHC). - : IEEE. - 9781538694619 - 9781538694626 ; , s. 592-597
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Konferensbidrag (refereegranskat)abstract
- Human-to-human touch conveys rich, meaningful social and emotional sentiment. At present, however, we understand neither the physical attributes that underlie such touch, nor how the attributes evoke responses in unique types of peripheral afferents. Indeed, nearly all electrophysiological studies use well-controlled but non-ecological stimuli. Here, we develop motion tracking and algorithms to quantify physical attributes indentation depth, shear velocity, contact area, and distance to the cutaneous sensory space (receptive field) of the afferent underlying human-to-human touch. In particular, 2-D video of the scene is combined with 3-D stereo infrared video of the touchers hand to measure contact interactions local to the receptive field of the receivers afferent. The combined and algorithmically corrected measurements improve accuracy, especially of occluded and misidentified fingers. Human subjects experiments track a toucher performing four gestures - single finger tapping, multi-finger tapping, multi-finger stroking and whole hand holding - while action potentials are recorded from a first-order afferent of the receiver. A case study with one rapidly-adapting (Pacinian) and one C-tactile afferent examines temporal ties between gestures and elicited action potentials. The results indicate this method holds promise in determining the roles of unique afferent types in encoding social and emotional touch attributes in their naturalistic delivery.
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| 8. |
- Larsson, Max, et al.
(författare)
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Role of C-tactile fibers in pain modulation : animal and human perspectives
- 2022
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Ingår i: Current Opinion in Behavioral Sciences. - : Elsevier. - 2352-1546. ; 43
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Tidskriftsartikel (refereegranskat)abstract
- C-tactile (CT) fibers, a population of unmyelinated (C) fibers that respond particularly well to gentle stroking, are widely believed to subserve affective touch. However, these fibers (termed C low-threshold mechanoreceptors (C-LTMRs) in non-human mammals) have also been proposed to be involved in the modulation of pain. Intriguingly, functional evidence from both human and animal studies indicates that CT/C-LTMR fibers can both contribute to allodynia as well as mediate pain inhibition. In the spinal cord, C-LTMR fibers form glomerular synaptic arrangements, providing input to several populations of interneurons within the nociceptive circuitry. Thus, the CT/C-LTMR system conveys signals that are subject to intricate processing in the spinal cord and is well-situated within spinal sensory pathways to enable the modulation of pain.
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| 9. |
- Liljencrantz, Jaquette, et al.
(författare)
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Slow brushing reduces heat pain in humans
- 2017
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Ingår i: European Journal of Pain. - : Wiley. - 1090-3801 .- 1532-2149. ; 21:7, s. 1173-1185
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Tidskriftsartikel (refereegranskat)abstract
- Background: C-tactile (CT) afferents are unmyelinated low-threshold mechanoreceptors optimized for signalling affective, gentle touch. In three separate psychophysical experiments, we examined the contribution of CT afferents to pain modulation. Methods: In total, 44 healthy volunteers experienced heat pain and CT optimal (slow brushing) and CT sub-optimal (fast brushing or vibration) stimuli. Three different experimental paradigms were used: Concurrent application of heat pain and tactile (slow brushing or vibration) stimulation; Slow brushing, applied for variable duration and intervals, preceding heat pain; Slow versus fast brushing preceding heat pain. Results: Slow brushing was effective in reducing pain, whereas fast brushing or vibration was not. The reduction in pain was significant not only when the CT optimal touch was applied simultaneously with the painful stimulus but also when the two stimuli were separated in time. For subsequent stimulation, the pain reduction was more pronounced for a shorter time interval between brushing and pain. Likewise, the effect was more robust when pain was preceded by a longer duration of brush stimulation. Strong CT-related pain reduction was associated with low anxiety and high calmness scores obtained by a state anxiety questionnaire. Conclusions: Slow brushing - optimal for CT activation - is effective in reducing pain from cutaneous heating. The precise mechanisms for the pain relief are as yet unknown but possible mechanisms include inhibition of nociceptive projection neurons at the level of the dorsal horn as well as analgesia through cortical mechanisms.
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| 10. |
- Mcintyre, Sarah, 1981-, et al.
(författare)
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The Effects of Ageing on Tactile Function in Humans
- 2021
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Ingår i: Neuroscience. - : Elsevier. - 0306-4522 .- 1873-7544. ; 464, s. 53-58
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Forskningsöversikt (refereegranskat)abstract
- Ageing is accompanied by a steady decline in touch sensitivity and acuity. Conversely, pleasant touch, such as experienced during a caress, is even more pleasant in old age. There are many physiological changes that might explain these perceptual changes, but researchers have not yet identified any specific mechanisms. Here, we review both the perceptual and structural changes to the touch system that are associated with ageing. The structural changes include reduced elasticity of the skin in older people, as well as reduced numbers and altered morphology of skin tactile receptors. Effects of ageing on the peripheral and central nervous systems include demyelination, which affects the timing of neural signals, as well as reduced numbers of peripheral nerve fibres. The ageing brain also undergoes complex changes in blood flow, metabolism, plasticity, neurotransmitter function, and, for touch, the body map in primary somatosensory cortex. Although several studies have attempted to find a direct link between perceptual and structural changes, this has proved surprisingly elusive. We also highlight the need for more evidence regarding age-related changes in peripheral nerve function in the hairy skin, as well as the social and emotional aspects of touch.
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