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Olausson H, Marshall A, Nagi SS, Cole J. Slow touch and ultrafast pain fibres: Revisiting peripheral nerve classification. Clin Neurophysiol 2024; 163:255-262. [PMID: 38704307 DOI: 10.1016/j.clinph.2024.04.008] [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] [Received: 01/12/2024] [Revised: 04/08/2024] [Accepted: 04/11/2024] [Indexed: 05/06/2024]
Abstract
One hundred years ago, Erlanger and Gasser demonstrated that conduction velocity is correlated with the diameter of a peripheral nerve axon. Later, they also demonstrated that the functional role of the axon is related to its diameter: touch is signalled by large-diameter axons, whereas pain and temperature are signalled by small-diameter axons. Certain discoveries in recent decades prompt a modification of this canonical classification. Here, we review the evidence for unmyelinated (C) fibres signalling touch at a slow conduction velocity and likely contributing to affective aspects of tactile information. We also review the evidence for large-diameter Aβ afferents signalling pain at ultrafast conduction velocity and likely contributing to the rapid nociceptive withdrawal reflex. These discoveries imply that conduction velocity is not as clear-cut an indication of the functional role of the axon as previously thought. We finally suggest that a future taxonomy of the peripheral afferent nervous system might be based on the combination of the axońs molecular expression and electrophysiological response properties.
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Affiliation(s)
- Håkan Olausson
- Department of Biomedical and Clinical Sciences, Linköping University, Linköping 58185, Sweden.
| | - Andrew Marshall
- School of Natural Sciences and Psychology, Liverpool John Moores University, L3 3AF Liverpool, UK
| | - Saad S Nagi
- Department of Biomedical and Clinical Sciences, Linköping University, Linköping 58185, Sweden
| | - Jonathan Cole
- University Hospitals, Dorset and Bournemouth University, Poole BH12 5BB, UK
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2
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Saramandi A, Au YK, Koukoutsakis A, Zheng CY, Godwin A, Bianchi-Berthouze N, Jewitt C, Jenkinson PM, Fotopoulou A. Tactile emoticons: Conveying social emotions and intentions with manual and robotic tactile feedback during social media communications. PLoS One 2024; 19:e0304417. [PMID: 38865322 PMCID: PMC11168615 DOI: 10.1371/journal.pone.0304417] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2023] [Accepted: 05/12/2024] [Indexed: 06/14/2024] Open
Abstract
Touch offers important non-verbal possibilities for socioaffective communication. Yet most digital communications lack capabilities regarding exchanging affective tactile messages (tactile emoticons). Additionally, previous studies on tactile emoticons have not capitalised on knowledge about the affective effects of certain mechanoreceptors in the human skin, e.g., the C-Tactile (CT) system. Here, we examined whether gentle manual stroking delivered in velocities known to optimally activate the CT system (defined as 'tactile emoticons'), during lab-simulated social media communications could convey increased feelings of social support and other prosocial intentions compared to (1) either stroking touch at CT sub-optimal velocities, or (2) standard visual emoticons. Participants (N = 36) felt more social intent with CT-optimal compared to sub-optimal velocities, or visual emoticons. In a second, preregistered study (N = 52), we investigated whether combining visual emoticons with tactile emoticons, this time delivered at CT-optimal velocities by a soft robotic device, could enhance the perception of prosocial intentions and affect participants' physiological measures (e.g., skin conductance rate) in comparison to visual emoticons alone. Visuotactile emoticons conveyed more social intent overall and in anxious participants affected physiological measures more than visual emoticons. The results suggest that emotional social media communications can be meaningfully enhanced by tactile emoticons.
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Affiliation(s)
- Alkistis Saramandi
- Department of Clinical, Educational and Health Psychology, University College London, London, United Kingdom
| | - Yee Ki Au
- Department of Clinical, Educational and Health Psychology, University College London, London, United Kingdom
| | - Athanasios Koukoutsakis
- Department of Clinical, Educational and Health Psychology, University College London, London, United Kingdom
| | - Caroline Yan Zheng
- Royal College of Art, London, United Kingdom
- KTH Royal Institute of Technology, Stockholm, Sweden
| | | | | | - Carey Jewitt
- UCL Knowledge Lab, Culture Communication and Media, University College London, London, United Kingdom
| | - Paul M. Jenkinson
- Department of Clinical, Educational and Health Psychology, University College London, London, United Kingdom
- Faculty of Psychology, Counselling and Psychotherapy, The Cairnmillar Institute, Melbourne, Australia
| | - Aikaterini Fotopoulou
- Department of Clinical, Educational and Health Psychology, University College London, London, United Kingdom
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3
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Sasaki K, Sakurai N, Yuguchi Y, Kasai S, Kodama N. Identification of areas of the brain activated by active stimulation in hairless skin. Behav Brain Res 2024; 458:114758. [PMID: 37952686 DOI: 10.1016/j.bbr.2023.114758] [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] [Received: 09/07/2023] [Revised: 11/08/2023] [Accepted: 11/09/2023] [Indexed: 11/14/2023]
Abstract
In the past few decades, neuroscientists have studied the physiological basis of pleasant touch. Unmyelinated low-threshold mechanoreceptors are central to the study of the physiological basis of pleasant touch. Research on pleasant stimuli has mostly focused on passive stimuli, and the brain activation sites for active pleasant stimuli are not clear. Therefore, the purpose of this study was to identify brain activation sites during active pleasant stimulation of hairless skin using functional magnetic resonance imaging. Forty-two healthy subjects aged 19 years or older were asked to actively grasp in five stimulus tasks. The comfort and sensations that occurred during the tasks were investigated using a questionnaire. Significant activation was found in the middle frontal gyrus when the hair ball and slime ball were grasped, while there was significant activation in the amygdala when grasping a squeeze ball compared to the tennis ball. In a questionnaire survey of the subjects, there was a significant difference in the comfort score between the tennis ball and the squeeze ball, but no significant correlation was found between the comfort scores and the brain sites of activation. Therefore, although active stimulation with the squeeze ball significantly activated the amygdala, it was not clear that the amygdala was significantly activated by active pleasant stimulation. In the future, it will be necessary to investigate the texture of the squeeze ball in more detail, and to increase the number of subjects for further study.
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Affiliation(s)
- Kei Sasaki
- Graduate School of Health and Welfare, Niigata University of Health and Welfare, 1398 Shimami-cho, Kita-ku, Niigata 950-3198, Japan
| | - Noriko Sakurai
- Department of Radiological Technology, Faculty of Medical Technology, Niigata University of Health and Welfare, 1398 Shimami-cho, Kita-ku, Niigata 950-3198, Japan
| | - Yukina Yuguchi
- Graduate School of Health and Welfare, Niigata University of Health and Welfare, 1398 Shimami-cho, Kita-ku, Niigata 950-3198, Japan
| | - Satoshi Kasai
- Department of Radiological Technology, Faculty of Medical Technology, Niigata University of Health and Welfare, 1398 Shimami-cho, Kita-ku, Niigata 950-3198, Japan
| | - Naoki Kodama
- Department of Radiological Technology, Faculty of Medical Technology, Niigata University of Health and Welfare, 1398 Shimami-cho, Kita-ku, Niigata 950-3198, Japan.
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4
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Bellard A, Trotter PD, McGlone FL, Cazzato V. Role of medial prefrontal cortex and primary somatosensory cortex in self and other-directed vicarious social touch: a TMS study. Soc Cogn Affect Neurosci 2023; 18:nsad060. [PMID: 37837378 PMCID: PMC10640852 DOI: 10.1093/scan/nsad060] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2023] [Revised: 08/11/2023] [Accepted: 10/05/2023] [Indexed: 10/16/2023] Open
Abstract
Conflicting evidence points to the contribution of several key nodes of the 'social brain' to the processing of both discriminatory and affective qualities of interpersonal touch. Whether the primary somatosensory cortex (S1) and the medial prefrontal cortex (mPFC), two brain areas vital for tactile mirroring and affective mentalizing, play a functional role in shared representations of C-tactile (CT) targeted affective touch is still a matter of debate. Here, we used offline continuous theta-burst transcranial magnetic stimulation (cTBS) to mPFC, S1 and vertex (control) prior to participants providing ratings of vicarious touch pleasantness for self and others delivered across several body sites at CT-targeted velocities. We found that S1-cTBS led to a significant increase in touch ratings to the self, with this effect being positively associated to levels of interoceptive awareness. Conversely, mPFC-cTBS reduced pleasantness ratings for touch to another person. These effects were not specific for CT-optimal (slow) stroking velocities, but rather they applied to all types of social touch. Overall, our findings challenge the causal role of the S1 and mPFC in vicarious affective touch and suggest that self- vs other-directed vicarious touch responses might crucially depend on the specific involvement of key social networks in gentle tactile interactions.
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Affiliation(s)
- Ashleigh Bellard
- School of Psychology, Faculty of Health, Liverpool John Moores University, Liverpool, UK
| | - Paula D Trotter
- School of Psychology, Faculty of Health, Liverpool John Moores University, Liverpool, UK
| | - Francis L McGlone
- Institute of Psychology, Health & Society, University of Liverpool, Liverpool, UK
| | - Valentina Cazzato
- School of Psychology, Faculty of Health, Liverpool John Moores University, Liverpool, UK
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5
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Marschallek BE, Löw A, Jacobsen T. You can touch this! Brain correlates of aesthetic processing of active fingertip exploration of material surfaces. Neuropsychologia 2023; 182:108520. [PMID: 36813106 DOI: 10.1016/j.neuropsychologia.2023.108520] [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: 06/30/2022] [Revised: 01/18/2023] [Accepted: 02/17/2023] [Indexed: 02/22/2023]
Abstract
The haptic exploration and aesthetic processing of all kinds of materials' surfaces are part of everyday life. In the present study, functional near-infrared spectroscopy (fNIRS) was used to investigate the brain correlates of active fingertip exploration of material surfaces and subsequent aesthetic judgments of their pleasantness (feels good or bad?). In absence of other sensory modalities, individuals (n = 21) performed lateral movements on a total of 48 textile and wood surfaces varying in terms of their roughness. Behavioral results confirmed the influence of the stimuli's roughness on aesthetic judgments, with smoother textures being rated as feeling better than rough textures. At the neural level, fNIRS activation results revealed an overall increased engagement of the contralateral sensorimotor areas as well as left prefrontal areas. Moreover, the perceived pleasantness modulated specific activations of left prefrontal areas with increasing pleasantness showing greater activations of these regions. Interestingly, this positive relationship between the individual aesthetic judgments and brain activity was most pronounced for smooth woods. These results demonstrate that positively valenced touch by actively exploring material surfaces is linked to left prefrontal activity and extend previous findings of affective touch underlying passive movements on hairy skin. We suggest that fNIRS can be a valuable tool to provide new insights in the field of experimental aesthetics.
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Affiliation(s)
- Barbara E Marschallek
- Experimental Psychology Unit, Helmut Schmidt University/University of the Federal Armed Forces Hamburg, Postbox 700822, 22008, Hamburg, Germany.
| | - Andreas Löw
- Experimental Psychology Unit, Helmut Schmidt University/University of the Federal Armed Forces Hamburg, Postbox 700822, 22008, Hamburg, Germany.
| | - Thomas Jacobsen
- Experimental Psychology Unit, Helmut Schmidt University/University of the Federal Armed Forces Hamburg, Postbox 700822, 22008, Hamburg, Germany.
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Meth EMS, Brandão LEM, van Egmond LT, Xue P, Grip A, Wu J, Adan A, Andersson F, Pacheco AP, Uvnäs-Moberg K, Cedernaes J, Benedict C. A weighted blanket increases pre-sleep salivary concentrations of melatonin in young, healthy adults. J Sleep Res 2023; 32:e13743. [PMID: 36184925 DOI: 10.1111/jsr.13743] [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: 07/03/2022] [Revised: 09/04/2022] [Accepted: 09/16/2022] [Indexed: 11/30/2022]
Abstract
Weighted blankets have emerged as a potential non-pharmacological intervention to ease conditions such as insomnia and anxiety. Despite a lack of experimental evidence, these alleged effects are frequently attributed to a reduced activity of the endogenous stress systems and an increased release of hormones such as oxytocin and melatonin. Thus, the aim of the present in-laboratory crossover study (26 young and healthy participants, including 15 men and 11 women) was to investigate if using a weighted blanket (~12% of body weight) at bedtime resulted in higher salivary concentrations of melatonin and oxytocin compared with a light blanket (~2.4% of body weight). We also examined possible differences in salivary concentrations of the stress hormone cortisol, salivary alpha-amylase activity (as an indicative metric of sympathetic nervous system activity), subjective sleepiness, and sleep duration. When using a weighted blanket, the 1 hour increase of salivary melatonin from baseline (i.e., 22:00) to lights off (i.e., 23:00) was about 32% higher (p = 0.011). No other significant differences were found between the blanket conditions, including subjective sleepiness and total sleep duration. Our study is the first to suggest that using a weighted blanket may result in a more significant release of melatonin at bedtime. Future studies should investigate whether the stimulatory effect on melatonin secretion is observed on a nightly basis when frequently using a weighted blanket over weeks to months. It remains to be determined whether the observed increase in melatonin may be therapeutically relevant for the previously described effects of the weighted blanket on insomnia and anxiety.
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Affiliation(s)
- Elisa M S Meth
- Department of Pharmaceutical Biosciences, Uppsala University, Uppsala, Sweden
| | | | - Lieve T van Egmond
- Department of Pharmaceutical Biosciences, Uppsala University, Uppsala, Sweden.,Department of Surgical Sciences, Uppsala University, Uppsala, Sweden
| | - Pei Xue
- Department of Pharmaceutical Biosciences, Uppsala University, Uppsala, Sweden
| | - Anastasia Grip
- Department of Pharmaceutical Biosciences, Uppsala University, Uppsala, Sweden
| | - Jiafei Wu
- Department of Pharmaceutical Biosciences, Uppsala University, Uppsala, Sweden
| | - Ayaat Adan
- Department of Pharmaceutical Biosciences, Uppsala University, Uppsala, Sweden
| | | | - André P Pacheco
- Department of Pharmaceutical Biosciences, Uppsala University, Uppsala, Sweden
| | - Kerstin Uvnäs-Moberg
- Department of Animal Environment and Health, Swedish University of Agricultural Sciences, Uppsala, Sweden
| | - Jonathan Cedernaes
- Department of Medical Sciences, Uppsala University, Uppsala, Sweden.,Department of Medical Cell Biology, Uppsala University, Uppsala, Sweden
| | - Christian Benedict
- Department of Pharmaceutical Biosciences, Uppsala University, Uppsala, Sweden
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Schirmer A, Lai O, Cham C, Lo C. Velocity-tuning of somatosensory EEG predicts the pleasantness of gentle caress. Neuroimage 2023; 265:119811. [PMID: 36526103 DOI: 10.1016/j.neuroimage.2022.119811] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2022] [Revised: 12/09/2022] [Accepted: 12/12/2022] [Indexed: 12/15/2022] Open
Abstract
Numerous studies have established an inverted u-shaped effect between the velocity of a caress and its pleasantness and linked this effect to the C-tactile (CT) system considered central for physical and mental health. This study probed whether cortical somatosensory representations predict and explain the inverted u-shaped effect and addressed associated individual differences. Study participants (N = 90) rated the pleasantness of stroking at varying velocities while their electroencephalogram was being recorded. An analysis across all participants replicated a preference for intermediate velocities, while a cluster analysis discriminated individuals who preferred slow (N = 43) from those who preferred fast stroking (N = 47). In both groups, intermediate velocities maximized amplitudes of a somatosensory event-related potential referred to as sN400, in line with the average rating effect. By contrast, group differences emerged in how velocity modulated a late positive potential (LPP) and Rolandic power. Notably, both the sN400 and the velocity-tuning of LPP and Rolandic power predicted the participants' pleasantness ratings. Participants were more likely to prefer slow over fast stroking the better their LPP and Rolandic power differentiated between different velocities. Together, these results shed light on the complexity of tactile affect. They corroborate an average preference for intermediate velocities that relates to largely shared effects of CT-targeted touch on the activity of somatosensory cortex. Additionally, they identify individual differences as a function of how accurately somatosensory cortex represents the velocity of peripheral input and suggest these differences are relevant for the extent to which individuals pursue beneficial, CT-targeted touch.
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Affiliation(s)
- Annett Schirmer
- Institute of Psychology, University of Innsbruck, Austria; Department of Psychology, Friedrich Schiller University Jena, Germany.
| | - Oscar Lai
- Department of Psychology, The Chinese University of Hong Kong, Hong Kong
| | - Clare Cham
- Department of Psychology, The Chinese University of Hong Kong, Hong Kong
| | - Clive Lo
- Department of Psychology, The Chinese University of Hong Kong, Hong Kong
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Atypical Response to Affective Touch in Children with Autism: Multi-Parametric Exploration of the Autonomic System. J Clin Med 2022; 11:jcm11237146. [PMID: 36498717 PMCID: PMC9737198 DOI: 10.3390/jcm11237146] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2022] [Revised: 11/21/2022] [Accepted: 11/29/2022] [Indexed: 12/02/2022] Open
Abstract
This study aimed at evaluating the autonomic response to pleasant affective touch in children with Autism Spectrum Disorders (ASD) and age-matched typically developing (TD) peers, thanks to multiple autonomic nervous system (ANS) parameters and by contrasting CT (C-tactile fibers) high- vs. low-density territory stimulations. We measured pupil diameter, skin conductance, and heart rate during gentle stroking of two skin territories (CT high- and low-density, respectively, forearm and palm of the hand) in thirty 6-12-year-old TD children and twenty ASD children. TD children showed an increase in pupil diameter and skin conductance associated with a heart rate deceleration in response to tactile stimulations at the two locations. Only the pupil was influenced by the stimulated location, with a later dilation peak following CT low-density territory stimulation. Globally, ASD children exhibited reduced autonomic responses, as well as different ANS baseline values compared to TD children. These atypical ANS responses to pleasant touch in ASD children were not specific to CT-fiber stimulation. Overall, these results point towards both basal autonomic dysregulation and lower tactile autonomic evoked responses in ASD, possibly reflecting lower arousal and related to social disengagement.
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A wearable soft robot that can alleviate the pain and fear of the wearer. Sci Rep 2022; 12:17003. [PMID: 36253420 PMCID: PMC9576738 DOI: 10.1038/s41598-022-21183-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2022] [Accepted: 09/23/2022] [Indexed: 12/29/2022] Open
Abstract
Social soft robotics may provide a new solution for alleviating human pain and fear. Here, we introduce a hand-held soft robot that can be clenched by the wearer. The robot comprises small airbags that can be inflated to provide the wearer with a feeling of being clenched. We then conducted an in-depth study of 66 adults who participated in a pain research protocol using thermal stimulation to investigate the effect of wearing the robot on pain perception and fear of injections. Pain assessment scale scores for perceived pain decreased significantly [Formula: see text] when participants wore the robot compared with the baseline condition in which the robot was not worn. In addition, the saliva test results showed a downward trend in oxytocin level when the robot provided the wearer with haptic feedback via the inflation of the internal airbags in response to the wearer's clench. Furthermore, the negative psychological state of participants, as measured using the positive and negative affect scale, improved significantly when wearing the robot. We also revealed that the salivary cortisol level, an indicator of stress, decreased significantly across all participants at the end of the experiment. In addition, participants' fear of injections was significantly improved after participation in the experiment. These results suggest that the wearable soft robot may alleviate the human perception of pain and fear in during medical treatments, such as vaccinations.
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Della Longa L, Sacchetti S, Farroni T, McGlone F. Does Nice or Nasty Matter? The Intensity of Touch Modulates the Rubber Hand Illusion. Front Psychol 2022; 13:901413. [PMID: 35769756 PMCID: PMC9234571 DOI: 10.3389/fpsyg.2022.901413] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2022] [Accepted: 05/23/2022] [Indexed: 11/18/2022] Open
Abstract
Our sense of body ownership results from the ongoing integration of perceptual information coming from the different senses (i.e., multisensory integration). The Rubber Hand Illusion (RHI) has been extensively studied to investigate the malleability of body ownership through contrasting multisensory information. Indeed, during the RHI, stroking a visible rubber hand synchronously to participants’ hand hidden from sight generates the illusion of ownership of the rubber hand (embodiment) and the mis-location of participants’ hand as closer to the rubber hand (proprioceptive drift). It is well known that the RHI is optimally evoked by a pleasant stroking (affective) touch, but what of an unpleasant (painful) stroking touch – does hedonic valence matter? To this aim, participants repeated the RHI while receiving different types of touch: pleasant, painful, and neutral. Results showed, for the first time, that the subjective intensity of the tactile stimulation experienced across the different conditions modulates the strength of the proprioceptive drift. Notably, participants reported a stronger RHI (mis-placed body ownership) from stimulation rated as more intense and involving an interoceptive activation (pain and pleasantness vs. neutral). We propose that interoceptive information, regardless of the valence of the stimuli (positive or negative), are perceived as more intense and enhance, through the activation of the limbic system, multisensory integration. In the context of the RHI, this translates to a stronger illusion in terms of proprioceptive drift.
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Affiliation(s)
- Letizia Della Longa
- Department of Developmental Psychology and Socialisation, University of Padova, Padua, Italy
- *Correspondence: Letizia Della Longa,
| | - Sofia Sacchetti
- School of Psychology, Liverpool John Moores University, Liverpool, United Kingdom
| | - Teresa Farroni
- Department of Developmental Psychology and Socialisation, University of Padova, Padua, Italy
| | - Francis McGlone
- School of Psychology, Liverpool John Moores University, Liverpool, United Kingdom
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Psychophysiology and motivated emotion: testing the affective touch hypothesis of C-tactile afferent function. Curr Opin Behav Sci 2022. [DOI: 10.1016/j.cobeha.2021.10.004] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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Della Longa L, Valori I, Farroni T. Interpersonal Affective Touch in a Virtual World: Feeling the Social Presence of Others to Overcome Loneliness. Front Psychol 2022; 12:795283. [PMID: 35087455 PMCID: PMC8787079 DOI: 10.3389/fpsyg.2021.795283] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2021] [Accepted: 12/10/2021] [Indexed: 12/25/2022] Open
Abstract
Humans are by nature social beings tuned to communicate and interact from the very beginning of their lives. The sense of touch represents the most direct and intimate channel of communication and a powerful means of connection between the self and the others. In our digital age, the development and diffusion of internet-based technologies and virtual environments offer new opportunities of communication overcoming physical distance. It however, happens that social interactions are often mediated, and the tactile aspects of communication are overlooked, thus diminishing the feeling of social presence, which may contribute to an increased sense of social disconnection and loneliness. The current manuscript aims to review the extant literature about the socio-affective dimension of touch and current advancements in interactive virtual environments in order to provide a new perspective on multisensory virtual communication. Specifically, we suggest that interpersonal affective touch might critically impact virtual social exchanges, promoting a sense of co-presence and social connection between individuals, possibly overcoming feelings of sensory loneliness. This topic of investigation will be of crucial relevance from a theoretical perspective aiming to understand how we integrate multisensory signals in processing and making sense of interpersonal exchanges, this is important in both typical and atypical populations. Moreover, it will pave the way to promising applications by exploring the possibility to use technical innovations to communicate more interactively in the case of people who suffer from social isolation and disconnection from others.
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Affiliation(s)
- Letizia Della Longa
- Department of Developmental Psychology and Socialization, University of Padova, Padua, Italy
| | - Irene Valori
- Department of Developmental Psychology and Socialization, University of Padova, Padua, Italy
| | - Teresa Farroni
- Department of Developmental Psychology and Socialization, University of Padova, Padua, Italy
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Sinhorim L, Amorim MDS, Ortiz ME, Bittencourt EB, Bianco G, da Silva FC, Horewicz VV, Schleip R, Reed WR, Mazzardo-Martins L, Martins DF. Potential Nociceptive Role of the Thoracolumbar Fascia: A Scope Review Involving In Vivo and Ex Vivo Studies. J Clin Med 2021; 10:jcm10194342. [PMID: 34640360 PMCID: PMC8509394 DOI: 10.3390/jcm10194342] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2021] [Revised: 09/09/2021] [Accepted: 09/20/2021] [Indexed: 12/23/2022] Open
Abstract
Nociceptive innervation of the thoracolumbar fascia (TLF) has been investigated over the past few decades; however, these studies have not been compiled or collectively appraised. The purpose of this scoping review was to assess current knowledge regarding nociceptive innervation of the TLF to better inform future mechanistic and clinical TLF research targeting lower back pain (LBP) treatment. PubMed, ScienceDirect, Cochrane, and Embase databases were searched in January 2021 using relevant descriptors encompassing fascia and pain. Eligible studies satisfied the following: (a) published in English; (b) preclinical and clinical (in vivo and ex vivo) studies; (c) original data; (d) included quantification of at least one TLF nociceptive component. Two-phase screening procedures were conducted by a pair of independent reviewers, after which data were extracted and summarized from eligible studies. The search resulted in 257 articles of which 10 met the inclusion criteria. Studies showed histological evidence of nociceptive nerve fibers terminating in lower back fascia, suggesting a TLF contribution to LBP. Noxious chemical injection or electrical stimulation into fascia resulted in longer pain duration and higher pain intensities than injections into subcutaneous tissue or muscle. Pre-clinical and clinical research provides histological and functional evidence of nociceptive innervation of TLF. Additional knowledge of fascial neurological components could impact LBP treatment.
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Affiliation(s)
- Larissa Sinhorim
- Experimental Neuroscience Laboratory (LaNEx), University of Southern Santa Catarina, Palhoça 88137-272, Brazil; (L.S.); (M.d.S.A.); (M.E.O.); (E.B.B.); (G.B.); (V.V.H.); (D.F.M.)
- Postgraduate Program in Health Sciences, University of Southern Santa Catarina, Palhoça 88137-272, Brazil
| | - Mayane dos Santos Amorim
- Experimental Neuroscience Laboratory (LaNEx), University of Southern Santa Catarina, Palhoça 88137-272, Brazil; (L.S.); (M.d.S.A.); (M.E.O.); (E.B.B.); (G.B.); (V.V.H.); (D.F.M.)
- Human Movement Sciences Graduate Program, College of Health and Sport Science at Santa Catarina State University, Florianópolis 88080-350, Brazil
| | - Maria Eugênia Ortiz
- Experimental Neuroscience Laboratory (LaNEx), University of Southern Santa Catarina, Palhoça 88137-272, Brazil; (L.S.); (M.d.S.A.); (M.E.O.); (E.B.B.); (G.B.); (V.V.H.); (D.F.M.)
- Postgraduate Program in Health Sciences, University of Southern Santa Catarina, Palhoça 88137-272, Brazil
| | - Edsel Balduino Bittencourt
- Experimental Neuroscience Laboratory (LaNEx), University of Southern Santa Catarina, Palhoça 88137-272, Brazil; (L.S.); (M.d.S.A.); (M.E.O.); (E.B.B.); (G.B.); (V.V.H.); (D.F.M.)
- Coastal Health Institute, Jacksonville, FL 32224, USA
| | - Gianluca Bianco
- Experimental Neuroscience Laboratory (LaNEx), University of Southern Santa Catarina, Palhoça 88137-272, Brazil; (L.S.); (M.d.S.A.); (M.E.O.); (E.B.B.); (G.B.); (V.V.H.); (D.F.M.)
- Research Laboratory of Posturology and Neuromodulation RELPON, Department of Human Neuroscience, Sapienza University, 00147 Rome, Italy
- Istituto di Formazione in Agopuntura e Neuromodulazione IFAN, 00147 Roma, Italy
| | | | - Verônica Vargas Horewicz
- Experimental Neuroscience Laboratory (LaNEx), University of Southern Santa Catarina, Palhoça 88137-272, Brazil; (L.S.); (M.d.S.A.); (M.E.O.); (E.B.B.); (G.B.); (V.V.H.); (D.F.M.)
- Postgraduate Program in Health Sciences, University of Southern Santa Catarina, Palhoça 88137-272, Brazil
| | - Robert Schleip
- Department of Sport and Health Sciences, Technical University of Munich, 80799 Munich, Germany
- Department for Medical Professions, DIPLOMA University of Applied Sciences, 37242 Bad Sooden-Allendorf, Germany
- Correspondence: ; Tel.: +49-89-346016
| | - William R. Reed
- Department of Physical Therapy, University of Alabama at Birmingham, Birmingham, AL 35294, USA;
- Rehabilitation Science Program, Departments of Physical and Occupational Therapy, School of Health Professions, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Leidiane Mazzardo-Martins
- Postgraduate Program in Neuroscience, Center of Biological Sciences, Federal University of Santa Catarina, Florianópolis 88040-900, Brazil;
| | - Daniel F. Martins
- Experimental Neuroscience Laboratory (LaNEx), University of Southern Santa Catarina, Palhoça 88137-272, Brazil; (L.S.); (M.d.S.A.); (M.E.O.); (E.B.B.); (G.B.); (V.V.H.); (D.F.M.)
- Postgraduate Program in Health Sciences, University of Southern Santa Catarina, Palhoça 88137-272, Brazil
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15
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Baumgartner JN, Quintana D, Leija L, Schuster NM, Bruno KA, Castellanos JP, Case LK. Widespread Pressure Delivered by a Weighted Blanket Reduces Chronic Pain: A Randomized Controlled Trial. THE JOURNAL OF PAIN 2021; 23:156-174. [PMID: 34425251 DOI: 10.1016/j.jpain.2021.07.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/21/2021] [Revised: 07/08/2021] [Accepted: 07/22/2021] [Indexed: 11/30/2022]
Abstract
Pleasant sensation is an underexplored avenue for modulation of chronic pain. Deeper pressure is perceived as pleasant and calming, and can improve sleep. Although pressure can reduce acute pain, its effect on chronic pain is poorly characterized. The current remote, double-blind, randomized controlled trial tested the hypothesis that wearing a heavy weighted blanket - providing widespread pressure to the body - relative to a light weighted blanket would reduce ratings of chronic pain, mediated by improvements in anxiety and sleep. Ninety-four adults with chronic pain were randomized to wear a 15-lb. (heavy) or 5-lb. (light) weighted blanket during a brief trial and overnight for one week. Measures of anxiety and chronic pain were collected pre- and post-intervention, and ratings of pain intensity, anxiety, and sleep were collected daily. After controlling for expectations and trait anxiety, the heavy weighted blanket produced significantly greater reductions in broad perceptions of chronic pain than the light weighted blanket (Cohen's f = .19, CI [-1.97, -.91]). This effect was stronger in individuals with high trait anxiety (P = .02). However, weighted blankets did not alter pain intensity ratings. Pain reductions were not mediated by anxiety or sleep. Given that the heavy weighted blanket was associated with greater modulation of affective versus sensory aspects of chronic pain, we propose that the observed reductions are due to interoceptive and social/affective effects of deeper pressure. Overall, we demonstrate that widespread pressure from a weighted blanket can reduce the severity of chronic pain, offering an accessible, home-based tool for chronic pain. The study purpose, targeted condition, study design, and primary and secondary outcomes were pre-registered in ClinicalTrials.gov (NCT04447885: "Weighted Blankets and Chronic Pain"). Perspective: This randomized-controlled trial showed that a 15-lb weighted blanket produced significantly greater reductions in broad perceptions of chronic pain relative to a 5-lb weighted blanket, particularly in highly anxious individuals. These findings are relevant to patients and providers seeking home-based, nondrug therapies for chronic pain relief.
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Affiliation(s)
- Jennifer N Baumgartner
- Department of Anesthesiology, University of California San Diego Health, La Jolla, California
| | - Desiree Quintana
- Department of Anesthesiology, University of California San Diego Health, La Jolla, California
| | - Linda Leija
- Department of Anesthesiology, University of California San Diego Health, La Jolla, California
| | - Nathaniel M Schuster
- Department of Anesthesiology, University of California San Diego Health, La Jolla, California
| | - Kelly A Bruno
- Department of Anesthesiology, University of California San Diego Health, La Jolla, California
| | - Joel P Castellanos
- Department of Anesthesiology, University of California San Diego Health, La Jolla, California
| | - Laura K Case
- Department of Anesthesiology, University of California San Diego Health, La Jolla, California.
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16
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Spaccasassi C, Frigione I, Maravita A. Bliss in and Out of the Body: The (Extra)Corporeal Space Is Impervious to Social Pleasant Touch. Brain Sci 2021; 11:brainsci11020225. [PMID: 33673297 PMCID: PMC7917648 DOI: 10.3390/brainsci11020225] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2021] [Revised: 02/08/2021] [Accepted: 02/10/2021] [Indexed: 11/16/2022] Open
Abstract
Slow, gentle stimulation of hairy skin is generally accompanied by hedonic sensations. This phenomenon, also known as (positive) affective touch, is likely to be the basis of affiliative interactions with conspecifics by promoting inter-individual bindings. Previous studies on healthy humans have demonstrated that affective touch can remarkably impact behavior. For instance, by administering the Rubber Hand Illusion (RHI) paradigm, the embodiment of a fake hand enhances after a slow, affective touch compared to a fast, neutral touch. However, results coming from this area are not univocal. In addition, there are no clues in the existing literature on the relationship between affective touch and the space around our body. To overcome these lacks, we carried out two separate experiments where participants underwent a RHI paradigm (Experiment 1) and a Visuo-Tactile Interaction task (Experiment 2), designed to tap into body representation and peripersonal space processing, respectively. In both experiments, an affective touch (CT-optimal, 3 cm/s) and neutral touch (CT-suboptimal, 18 cm/s) were delivered by the experimenter on the dorsal side of participants’ hand through a “skin to skin” contact. In Experiment 1, we did not find any modulation of body representation—not at behavioral nor at a physiological level—by affective touch. In Experiment 2, no visuo-tactile spatial modulation emerged depending upon the pleasantness of the touch received. These null findings are interpreted in the light of the current scientific context where the real nature of affective touch is often misguided, and they offer the possibility to pave the way for understanding the real effects of affective touch on body/space representation.
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Affiliation(s)
- Chiara Spaccasassi
- Centre for Studies and Research in Cognitive Neuroscience, ‘Alma Mater Studiorum’, Department of Psychology, Cesena Campus, Bologna University, 47521 Cesena, Italy
- Correspondence:
| | - Ivana Frigione
- Department of Psychology, University of Milano-Bicocca, Piazza Ateneo Nuovo 1, 20126 Milano, Italy; (I.F.); (A.M.)
| | - Angelo Maravita
- Department of Psychology, University of Milano-Bicocca, Piazza Ateneo Nuovo 1, 20126 Milano, Italy; (I.F.); (A.M.)
- Milan Centre for Neurosciences, 20126 Milano, Italy
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17
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Innocuous pressure sensation requires A-type afferents but not functional ΡΙΕΖΟ2 channels in humans. Nat Commun 2021; 12:657. [PMID: 33510158 PMCID: PMC7844252 DOI: 10.1038/s41467-021-20939-5] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2019] [Accepted: 01/04/2021] [Indexed: 01/17/2023] Open
Abstract
The sensation of pressure allows us to feel sustained compression and body strain. While our understanding of cutaneous touch has grown significantly in recent years, how deep tissue sensations are detected remains less clear. Here, we use quantitative sensory evaluations of patients with rare sensory disorders, as well as nerve blocks in typical individuals, to probe the neural and genetic mechanisms for detecting non-painful pressure. We show that the ability to perceive innocuous pressures is lost when myelinated fiber function is experimentally blocked in healthy volunteers and that two patients lacking Aβ fibers are strikingly unable to feel innocuous pressures at all. We find that seven individuals with inherited mutations in the mechanoreceptor PIEZO2 gene, who have major deficits in touch and proprioception, are nearly as good at sensing pressure as healthy control subjects. Together, these data support a role for Aβ afferents in pressure sensation and suggest the existence of an unknown molecular pathway for its detection. The mechanisms underlying deep pressure sensing are not fully understood. Here the authors demonstrate that while two individuals lacking Aβ fibers demonstrate impaired deep pressure sensing, seven individuals with PIEZO2 loss of function mutations display normal deep pressure responses.
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18
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Crucianelli L, Demartini B, Goeta D, Nisticò V, Saramandi A, Bertelli S, Todisco P, Gambini O, Fotopoulou A. The Anticipation and Perception of Affective Touch in Women with and Recovered from Anorexia Nervosa. Neuroscience 2020; 464:143-155. [PMID: 32937191 DOI: 10.1016/j.neuroscience.2020.09.013] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2020] [Revised: 09/01/2020] [Accepted: 09/02/2020] [Indexed: 11/19/2022]
Abstract
Disruptions in reward processing and anhedonia have long been observed in Anorexia Nervosa (AN). Interoceptive deficits have also been observed in AN, including reduced tactile pleasure. However, the extent to which this tactile anhedonia is specifically liked to an impairment in a specialised, interoceptive C-tactile system originating at the periphery, or a more top-down mechanism in the processing of tactile pleasantness remains debated. Here, we investigated differences between patients with and recovered from AN (RAN) and healthy controls (HC) in the perception of pleasantness of touch delivered in a CT-optimal versus a CT-non-optimal manner, and in their top-down, anticipatory beliefs about the perceived pleasantness of touch. To this end, we measured the anticipated pleasantness of various materials touching the skin and the perceived pleasantness of light, dynamic touch applied to the forearm of 27 women with AN, 24 women who have recovered and 30 HCs using C Tactile (CT) afferents-optimal (slow) and non-optimal (fast) velocities. Our results showed that both clinical groups anticipated tactile experiences and rated delivered tactile stimuli as less pleasant than HCs, but the latter difference was not related to the CT optimality of the stimulation. Instead, differences in the perception of CT-optimal touch were predicted by differences in top-down beliefs, alexithymia and interoceptive sensibility. Thus, tactile anhedonia in AN might persist as a trait even after otherwise successful recovery of AN and it is not linked to a bottom-up interoceptive deficit in the CT system, but rather to a learned, defective top-down anticipation of tactile pleasantness.
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Affiliation(s)
- Laura Crucianelli
- Department of Clinical, Educational and Health Psychology, University College London, London, UK; Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden.
| | - Benedetta Demartini
- Department of Clinical, Educational and Health Psychology, University College London, London, UK; Department of Health Sciences, University of Milan, Milan, Italy; Psychiatry Unit, ASST Santi Paolo e Carlo, S. Paolo General Hospital, Milan, Italy; Aldo Ravelli Research Center for Neurotechnology and Experimental Brain Therapeutics, University of Milan, Italy
| | - Diana Goeta
- Department of Health Sciences, University of Milan, Milan, Italy; Psychiatry Unit, ASST Santi Paolo e Carlo, S. Paolo General Hospital, Milan, Italy
| | - Veronica Nisticò
- Department of Clinical, Educational and Health Psychology, University College London, London, UK; Department of Health Sciences, University of Milan, Milan, Italy; Aldo Ravelli Research Center for Neurotechnology and Experimental Brain Therapeutics, University of Milan, Italy
| | - Alkistis Saramandi
- Department of Clinical, Educational and Health Psychology, University College London, London, UK
| | - Sara Bertelli
- Psychiatry Unit, ASST Santi Paolo e Carlo, S. Paolo General Hospital, Milan, Italy
| | | | - Orsola Gambini
- Department of Health Sciences, University of Milan, Milan, Italy; Psychiatry Unit, ASST Santi Paolo e Carlo, S. Paolo General Hospital, Milan, Italy; Aldo Ravelli Research Center for Neurotechnology and Experimental Brain Therapeutics, University of Milan, Italy
| | - Aikaterini Fotopoulou
- Department of Clinical, Educational and Health Psychology, University College London, London, UK
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19
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Case LK, Liljencrantz J, McCall MV, Bradson M, Necaise A, Tubbs J, Olausson H, Wang B, Bushnell MC. Pleasant Deep Pressure: Expanding the Social Touch Hypothesis. Neuroscience 2020; 464:3-11. [PMID: 32768616 DOI: 10.1016/j.neuroscience.2020.07.050] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2020] [Revised: 07/20/2020] [Accepted: 07/21/2020] [Indexed: 11/25/2022]
Abstract
Neuroscientific research on pleasant touch has focused on the C-tactile pathway for gentle stroking and has successfully explained how these sensory fibers transmit information about affective social touch to the brain and induce sensations of pleasantness. The C-tactile social/affective touch hypothesis even proposes that C-tactile fibers form a privileged pathway underlying social touch. However, deep pressure is a type of touch commonly considered pleasant and calming, occurring in hugs, cuddling, and massage. In this paper we introduce a paradigm for studying pleasant deep pressure and propose that it constitutes another important form of social touch. We describe development of the oscillating compression sleeve (OCS) as one approach to administering deep pressure and demonstrate that this touch is perceived as pleasant and calming. Further, we show that deep pressure can be imaged with functional magnetic resonance imaging (MRI) using the air-pressure-driven OCS and that deep pressure activates brain regions highly similar to those that respond to C-tactile stroking, as well as regions not activated by stroking. We propose that deep pressure constitutes another social touch pathway of evolutionary importance signaling the close proximity of conspecifics.
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Affiliation(s)
- Laura K Case
- National Center for Complementary and Integrative Health, NIH, Bethesda, MD, United States; Department of Anesthesiology, UC San Diego School of Medicine, La Jolla, CA, United States.
| | - Jaquette Liljencrantz
- National Center for Complementary and Integrative Health, NIH, Bethesda, MD, United States
| | - Micaela V McCall
- National Center for Complementary and Integrative Health, NIH, Bethesda, MD, United States
| | - Megan Bradson
- National Center for Complementary and Integrative Health, NIH, Bethesda, MD, United States
| | - Aaron Necaise
- National Center for Complementary and Integrative Health, NIH, Bethesda, MD, United States
| | - Justin Tubbs
- National Center for Complementary and Integrative Health, NIH, Bethesda, MD, United States
| | - Håkan Olausson
- Center for Social and Affective Neuroscience, Department of Clinical and Experimental Medicine, Linköping University, Linköping, Sweden
| | - Binquan Wang
- National Center for Complementary and Integrative Health, NIH, Bethesda, MD, United States
| | - M Catherine Bushnell
- National Center for Complementary and Integrative Health, NIH, Bethesda, MD, United States
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20
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Costa R, Tamascia ML, Sanches A, Moreira RP, Cunha TS, Nogueira MD, Casarini DE, Marcondes FK. Tactile stimulation of adult rats modulates hormonal responses, depression-like behaviors, and memory impairment induced by chronic mild stress: Role of angiotensin II. Behav Brain Res 2020; 379:112250. [DOI: 10.1016/j.bbr.2019.112250] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2019] [Revised: 09/17/2019] [Accepted: 09/17/2019] [Indexed: 12/19/2022]
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21
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Haggarty CJ, Malinowski P, McGlone FP, Walker SC. Autistic traits modulate cortical responses to affective but not discriminative touch. Eur J Neurosci 2020; 51:1844-1855. [PMID: 31793072 DOI: 10.1111/ejn.14637] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2019] [Revised: 11/15/2019] [Accepted: 11/28/2019] [Indexed: 02/03/2023]
Abstract
The sense of touch is primarily considered a discriminative and exteroceptive sense, facilitating the detection, manipulation and exploration of objects, via an array of low-threshold mechanoreceptors and fast conducting A-beta (Aβ) afferents. However, a class of unmyelinated, low-threshold mechanoreceptors identified in the hairy skin of mammals have been proposed to constitute a second, anatomically distinct system coding the affective qualities of touch. Unlike Aβs, which increase their firing rate linearly with the velocity of a stimulus moving across their receptive field, the response of these C-tactile afferents (CTs) is described by an inverted 'U' curve fit, responding optimally to a skin temperature stimulus moving at between 1 and 10 cm/s. Given the distinct velocity tuning of these fast and slow touch fibres, here we used event-related potentials to compare the time course of neural responses to 1st (fast) and 2nd (slow) touch systems. We identified a higher amplitude P300 in response to fast, Aβ-targeted, versus slow CT-targeted, stroking touch. In contrast, we identified a previously described, C-fibre specific, ultra-late potential (ULP) associated with CT-targeted input. Of special note as regards the function of CTs is that the amplitude of the ULP was negatively correlated with self-reported levels of autistic traits, which is consistent with the hypothesized affective and social significance of this response. Taken together, these findings provide further support for distinct discriminative and affective touch systems and suggests the temporal resolution of EEG provides an as yet underutilized tool for exploring individual differences in response sensitivity to CT-targeted touch.
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Affiliation(s)
- Connor J Haggarty
- Research Centre for Brain & Behaviour, School of Natural Sciences & Psychology, Liverpool John Moores University, Liverpool, UK
| | - Peter Malinowski
- Research Centre for Brain & Behaviour, School of Natural Sciences & Psychology, Liverpool John Moores University, Liverpool, UK
| | - Francis P McGlone
- Research Centre for Brain & Behaviour, School of Natural Sciences & Psychology, Liverpool John Moores University, Liverpool, UK.,Institute of Psychology, Health & Society, University of Liverpool, Liverpool, UK
| | - Susannah C Walker
- Research Centre for Brain & Behaviour, School of Natural Sciences & Psychology, Liverpool John Moores University, Liverpool, UK
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22
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Marshall AG, Sharma ML, Marley K, Olausson H, McGlone FP. Spinal signalling of C-fiber mediated pleasant touch in humans. eLife 2019; 8:e51642. [PMID: 31872799 PMCID: PMC6964968 DOI: 10.7554/elife.51642] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2019] [Accepted: 12/23/2019] [Indexed: 01/06/2023] Open
Abstract
C-tactile afferents form a distinct channel that encodes pleasant tactile stimulation. Prevailing views indicate they project, as with other unmyelinated afferents, in lamina I-spinothalamic pathways. However, we found that spinothalamic ablation in humans, whilst profoundly impairing pain, temperature and itch, had no effect on pleasant touch perception. Only discriminative touch deficits were seen. These findings preclude privileged C-tactile-lamina I-spinothalamic projections and imply integrated hedonic and discriminative spinal processing from the body.
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Affiliation(s)
- Andrew G Marshall
- Institute of Aging and Chronic DiseaseUniversity of LiverpoolLiverpoolUnited Kingdom
- School of Natural Sciences and PsychologyLiverpool John Moores UniversityLiverpoolUnited Kingdom
- Department of Pain MedicineWalton Centre NHS Foundation TrustLiverpoolUnited Kingdom
| | - Manohar L Sharma
- Department of Pain MedicineWalton Centre NHS Foundation TrustLiverpoolUnited Kingdom
| | - Kate Marley
- Specialist Palliative Care TeamUniversity Hospital AintreeLiverpoolUnited Kingdom
| | - Hakan Olausson
- Specialist Palliative Care TeamUniversity Hospital AintreeLiverpoolUnited Kingdom
- Center for Social and Affective NeuroscienceLinköping UniversityLinköpingSweden
- Department of Clinical NeurophysiologyLinköping University HospitalLinköpingSweden
| | - Francis P McGlone
- School of Natural Sciences and PsychologyLiverpool John Moores UniversityLiverpoolUnited Kingdom
- Institute of Psychology, Health and SocietyUniversity of LiverpoolLiverpoolUnited Kingdom
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23
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Nagi SS, Marshall AG, Makdani A, Jarocka E, Liljencrantz J, Ridderström M, Shaikh S, O’Neill F, Saade D, Donkervoort S, Foley AR, Minde J, Trulsson M, Cole J, Bönnemann CG, Chesler AT, Bushnell MC, McGlone F, Olausson H. An ultrafast system for signaling mechanical pain in human skin. SCIENCE ADVANCES 2019; 5:eaaw1297. [PMID: 31281886 PMCID: PMC6609212 DOI: 10.1126/sciadv.aaw1297] [Citation(s) in RCA: 75] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/05/2018] [Accepted: 05/23/2019] [Indexed: 06/09/2023]
Abstract
The canonical view is that touch is signaled by fast-conducting, thickly myelinated afferents, whereas pain is signaled by slow-conducting, thinly myelinated ("fast" pain) or unmyelinated ("slow" pain) afferents. While other mammals have thickly myelinated afferents signaling pain (ultrafast nociceptors), these have not been demonstrated in humans. Here, we performed single-unit axonal recordings (microneurography) from cutaneous mechanoreceptive afferents in healthy participants. We identified A-fiber high-threshold mechanoreceptors (A-HTMRs) that were insensitive to gentle touch, encoded noxious skin indentations, and displayed conduction velocities similar to A-fiber low-threshold mechanoreceptors. Intraneural electrical stimulation of single ultrafast A-HTMRs evoked painful percepts. Testing in patients with selective deafferentation revealed impaired pain judgments to graded mechanical stimuli only when thickly myelinated fibers were absent. This function was preserved in patients with a loss-of-function mutation in mechanotransduction channel PIEZO2. These findings demonstrate that human mechanical pain does not require PIEZO2 and can be signaled by fast-conducting, thickly myelinated afferents.
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Affiliation(s)
- Saad S. Nagi
- Center for Social and Affective Neuroscience, Linköping University, S-581 85 Linköping, Sweden
- Department of Clinical Neurophysiology, Linköping University Hospital, S-581 85 Linköping, Sweden
- School of Medicine, Western Sydney University, Penrith, NSW 2751, Australia
| | - Andrew G. Marshall
- Faculty of Life Sciences, University of Manchester, M13 9PL Manchester, UK
- School of Natural Sciences and Psychology, Liverpool John Moores University, L3 3AF Liverpool, UK
| | - Adarsh Makdani
- School of Natural Sciences and Psychology, Liverpool John Moores University, L3 3AF Liverpool, UK
| | - Ewa Jarocka
- Department of Integrative Medical Biology, Umeå University, S-901 87 Umeå, Sweden
| | - Jaquette Liljencrantz
- National Center for Complementary and Integrative Health, National Institutes of Health, Bethesda, MD 20892, USA
- Department of Anesthesiology and Intensive Care, Institute of Clinical Sciences, Sahlgrenska Academy, University of Gothenburg, S-413 45 Gothenburg, Sweden
| | - Mikael Ridderström
- Department of Surgery, Unit of Orthopedics, Perioperative Sciences, Umeå University Hospital, 901 85 Umeå, Sweden
| | - Sumaiya Shaikh
- Center for Social and Affective Neuroscience, Linköping University, S-581 85 Linköping, Sweden
- School of Medicine, Western Sydney University, Penrith, NSW 2751, Australia
| | - Francis O’Neill
- School of Dentistry, Institute of Clinical Sciences, University of Liverpool, L3 5PS Liverpool, UK
| | - Dimah Saade
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892, USA
| | - Sandra Donkervoort
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892, USA
| | - A. Reghan Foley
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892, USA
| | - Jan Minde
- Department of Surgery, Unit of Orthopedics, Perioperative Sciences, Umeå University Hospital, 901 85 Umeå, Sweden
| | - Mats Trulsson
- Department of Dental Medicine, Karolinska Institute, S-141 04 Huddinge, Sweden
| | - Jonathan Cole
- Centre of Postgraduate Medical Research and Education, Bournemouth University, Poole BH12 5BB, UK
| | - Carsten G. Bönnemann
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892, USA
| | - Alexander T. Chesler
- National Center for Complementary and Integrative Health, National Institutes of Health, Bethesda, MD 20892, USA
| | - M. Catherine Bushnell
- National Center for Complementary and Integrative Health, National Institutes of Health, Bethesda, MD 20892, USA
| | - Francis McGlone
- School of Natural Sciences and Psychology, Liverpool John Moores University, L3 3AF Liverpool, UK
- Institute of Psychology, Health and Society, University of Liverpool, L3 5DA Liverpool, UK
| | - Håkan Olausson
- Center for Social and Affective Neuroscience, Linköping University, S-581 85 Linköping, Sweden
- Department of Clinical Neurophysiology, Linköping University Hospital, S-581 85 Linköping, Sweden
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24
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EEG captures affective touch: CT-optimal touch and neural oscillations. COGNITIVE AFFECTIVE & BEHAVIORAL NEUROSCIENCE 2019; 18:155-166. [PMID: 29404917 DOI: 10.3758/s13415-017-0560-6] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Tactile interactions are of developmental importance to social and emotional interactions across species. In beginning to understand the affective component of tactile stimulation, research has begun to elucidate the neural mechanisms that underscore slow, affective touch. Here, we extended this emerging body of work and examined whether affective touch (C tactile [CT]-optimal speed), as compared to nonaffective touch (non-CT-optimal speed) and no touch conditions, modulated EEG oscillations. We report an attenuation in alpha and beta activity to affective and nonaffective touch relative to the no touch condition. Further, we found an attenuation in theta activity specific to the affective, as compared to the nonaffective touch and no touch conditions. Similar to theta, we also observed an attenuation of beta oscillations during the affective touch condition, although only in parietal scalp sites. Decreased activity in theta and parietal-beta ranges may reflect attentional-emotional regulatory mechanisms; however, future work is needed to provide insight into the potential neural coupling between theta and beta and their specific role in encoding slow, tactile stimulation.
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25
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von Mohr M, Krahé C, Beck B, Fotopoulou A. The social buffering of pain by affective touch: a laser-evoked potential study in romantic couples. Soc Cogn Affect Neurosci 2019; 13:1121-1130. [PMID: 30247679 PMCID: PMC6234321 DOI: 10.1093/scan/nsy085] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2018] [Accepted: 09/21/2018] [Indexed: 01/05/2023] Open
Abstract
Pain is modulated by social context. Recent neuroimaging studies have shown that romantic partners can provide a potent form of social support during pain. However, such studies have only focused on passive support, finding a relatively late-onset modulation of pain-related neural processing. In this study, we examined for the first time dynamic touch by one’s romantic partner as an active form of social support. Specifically, 32 couples provided social, active, affective (vs active but neutral) touch according to the properties of a specific C-tactile afferent pathway to their romantic partners, who then received laser-induced pain. We measured subjective pain ratings and early N1 and later N2-P2 laser-evoked potentials (LEPs) to noxious stimulation, as well as individual differences in adult attachment style. We found that affective touch from one’s partner reduces subjective pain ratings and similarly attenuates LEPs both at earlier (N1) and later (N2-P2) stages of cortical processing. Adult attachment style did not affect LEPs, but attachment anxiety had a moderating role on pain ratings. This is the first study to show early neural modulation of pain by active, partner touch, and we discuss these findings in relation to the affective and social modulation of sensory salience.
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Affiliation(s)
- Mariana von Mohr
- Research Department of Clinical, Educational and Health Psychology, University College London, London, UK
| | - Charlotte Krahé
- Department of Psychology, Institute of Psychiatry, Psychology, and Neuroscience, King's College London, London, UK
| | - Brianna Beck
- Institute of Cognitive Neuroscience, University College London, London, UK
| | - Aikaterini Fotopoulou
- Research Department of Clinical, Educational and Health Psychology, University College London, London, UK
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26
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27
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Touch targeting C-tactile afferent fibers has a unique physiological pattern: A combined electrodermal and facial electromyography study. Biol Psychol 2019; 140:55-63. [DOI: 10.1016/j.biopsycho.2018.11.006] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2018] [Revised: 11/16/2018] [Accepted: 11/19/2018] [Indexed: 12/25/2022]
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28
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Greenspon CM, Battell EE, Devonshire IM, Donaldson LF, Chapman V, Hathway GJ. Lamina-specific population encoding of cutaneous signals in the spinal dorsal horn using multi-electrode arrays. J Physiol 2018; 597:377-397. [PMID: 30390415 PMCID: PMC6332738 DOI: 10.1113/jp277036] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2018] [Accepted: 10/31/2018] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS Traditional, widely used in vivo electrophysiological techniques for the investigation of spinal processing of somatosensory information fail to account for the diverse functions of each lamina. To overcome this oversimplification, we have used multi-electrode arrays, in vivo, to simultaneously record neuronal activity across all laminae of the spinal dorsal horn. Multi-electrode arrays are sensitive enough to detect lamina- and region-specific encoding of different subtypes of afferent fibres and to detect short-lived changes in synaptic plasticity as measured by the application of cutaneous electrical stimulation of varying intensity and frequency. Differential encoding of innocuous and noxious thermal and mechanical stimuli were also detected across the laminae with the technique, as were the effects of the application of capsaicin. This new approach to the study of the dorsal spinal cord produces significantly more information per experiment, permitting accelerated research whilst also permitting the effects of pharmacological tools to modulate network responses. ABSTRACT The dorsal horn (DH) of the spinal cord is a complex laminar structure integrating peripheral signals into the central nervous system. Spinal somatosensory processing is commonly measured electrophysiologically in vivo by recording the activity of individual wide-dynamic-range neurons in the deep DH and extrapolating their behaviour to all cells in every lamina. This fails to account for the specialized processes that occur in each lamina and the considerable heterogeneity in cellular phenotype within and between laminae. Here we overcome this oversimplification by employing linear multi-electrode arrays (MEAs) in the DH of anaesthetized rats to simultaneously measure activity across all laminae. The MEAs, comprising 16 channels, were inserted into the lumbar dorsal horn and peripheral neurons activated electrically via transcutaneous electrodes and ethologically with von Frey hairs (vFHs) or an aluminium heating block. Ascending electrical stimuli showed fibre thresholds with distinct dorsoventral innervation profiles. Wind up was observed across the DH during the C-fibre and post-discharge latencies following 0.5 Hz stimulation. Intrathecal application of morphine (5 ng/50 μl) significantly reduced Aδ- and C-fibre-evoked activity in deep and superficial DH. Light vFHs (≤10 g) predominantly activated intermediate and deep laminae whereas noxious vFHs (26 g) also activated the superficial laminae. Noxious heat (55°C) induced significantly greater activity in the superficial and deep laminae than the innocuous control (30°C). The application of these arrays produced the first description of the processing of innocuous and noxious stimuli throughout the intact DH.
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Affiliation(s)
- Charles M Greenspon
- School of Life Sciences, The University of Nottingham, Nottingham, NG7 2UH, UK
| | - Emma E Battell
- School of Life Sciences, The University of Nottingham, Nottingham, NG7 2UH, UK
| | - Ian M Devonshire
- Bio-Support Unit, The University of Nottingham, Nottingham, NG7 2UH, UK
| | - Lucy F Donaldson
- School of Life Sciences, The University of Nottingham, Nottingham, NG7 2UH, UK.,Arthritis Research UK Pain Centre, The University of Nottingham, Nottingham, NG7 2UH, UK
| | - Victoria Chapman
- School of Life Sciences, The University of Nottingham, Nottingham, NG7 2UH, UK.,Arthritis Research UK Pain Centre, The University of Nottingham, Nottingham, NG7 2UH, UK
| | - Gareth J Hathway
- School of Life Sciences, The University of Nottingham, Nottingham, NG7 2UH, UK
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29
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Touch-induced pupil size reflects stimulus intensity, not subjective pleasantness. Exp Brain Res 2018; 237:201-210. [PMID: 30374784 PMCID: PMC6514109 DOI: 10.1007/s00221-018-5404-2] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2018] [Accepted: 10/13/2018] [Indexed: 11/30/2022]
Abstract
Interpersonal touch is known to influence human communication and emotion. An important system for interpersonal touch is the C-tactile (CT) system, which is activated by a soft stroke on hairy skin with a velocity of 1–10 cms−1. This system been proposed to play a unique role in hedonic valence and emotion of touch. For other sensory modalities, hedonic processing has been associated with pupil dilation. However, it is unclear whether pupil dilation can be modulated by hedonic touch. The current study investigated in two experiments how pupil size reacts to both affective and non-affective stroking. Pupil-size data were obtained to investigate differences between stroking conditions. In addition, an adjusted version of the Touch Perception Task (TPT) was used to assess subjective touch pleasantness ratings. In Experiment 1, affective (3 cms−1) and non-affective (0.3 and 30 cms−1) stroking was applied to the dorsal side of the right hand. Results revealed that stroking velocity had a significant effect on TPT-item scores, showing higher that affective touch was rated as more pleasant compared to non-affective touch, thereby replicating the previous studies. Results, however, revealed no specific pupil dilation for the 3 cms−1 condition; instead, a logarithmic relation was found between pupil-size dilation and stroking velocity. This relation was confirmed in a second experiment. Furthermore, the palm of the hand was used as a control site for tactile stimulation, for which similar findings were obtained as for the dorsal side of the hand. In addition, skin conductance recordings showed a pattern of response to different stroking velocities similar to pupil dilation. These results suggest that pupil-size dilation does respond to tactile input, but that this response is related to arousal caused by changes in stimulus intensity (e.g., stroking velocity) rather than specific C-tactile stimulation.
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30
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Krahé C, von Mohr M, Gentsch A, Guy L, Vari C, Nolte T, Fotopoulou A. Sensitivity to CT-optimal, Affective Touch Depends on Adult Attachment Style. Sci Rep 2018; 8:14544. [PMID: 30266979 PMCID: PMC6162325 DOI: 10.1038/s41598-018-32865-6] [Citation(s) in RCA: 47] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2018] [Accepted: 09/06/2018] [Indexed: 12/27/2022] Open
Abstract
Affective touch supports affiliative bonds and social cognition. In particular, gentle, stroking touch, which has recently been associated with the C Tactile (CT) system, is typically perceived as pleasant and prosocial. However, it remains unknown whether pre-existing models of social relating influence the perception of CT-optimal touch. In this study (N = 44 adults), we examined how individual differences in attachment styles relate to the perception of CT-optimal touch, as well as to a different modality of interoception, namely heartbeat perception. Using the gold-standard assessment of attachment (Adult Attachment Interview), we found that insecure attachment was associated with reduced pleasantness discrimination between CT-optimal vs. non-CT optimal touch. Acknowledging the different traditions in measuring attachment, we also used a well-validated self-report questionnaire that pertains to explicit representations of current close relationships. Using this measure, we found that higher scores in attachment anxiety (but not attachment avoidance) were associated with reduced pleasantness discrimination between CT-optimal vs. non-CT optimal touch. Attachment patterns (in both measures) were not related to cardiac perception accuracy. These results corroborate and extend previous literature on CT-optimal touch and its relation with affiliative bonds and social cognition. Given that attachment was not related to perceived cardiac accuracy, these findings point to the specificity of the relationship between CT-optimal touch and attachment.
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Affiliation(s)
- Charlotte Krahé
- Institute of Psychiatry, Psychology and Neuroscience, King's College London, London, UK
| | - Mariana von Mohr
- Research Department of Clinical, Educational and Health Psychology, University College London, London, UK.
| | - Antje Gentsch
- Research Department of Clinical, Educational and Health Psychology, University College London, London, UK
| | - Lisette Guy
- Research Department of Clinical, Educational and Health Psychology, University College London, London, UK
| | - Chiara Vari
- Institute of Psychiatry, Psychology and Neuroscience, King's College London, London, UK
| | - Tobias Nolte
- Wellcome Trust Centre for Neuroimaging, University College London, London, UK
| | - Aikaterini Fotopoulou
- Research Department of Clinical, Educational and Health Psychology, University College London, London, UK
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31
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Edwards DJ, Young H, Cutis A, Johnston R. The Immediate Effect of Therapeutic Touch and Deep Touch Pressure on Range of Motion, Interoceptive Accuracy and Heart Rate Variability: A Randomized Controlled Trial With Moderation Analysis. Front Integr Neurosci 2018; 12:41. [PMID: 30297988 PMCID: PMC6160827 DOI: 10.3389/fnint.2018.00041] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2018] [Accepted: 09/06/2018] [Indexed: 12/20/2022] Open
Abstract
Background: There is paucity in the literature regarding the role of the interoceptive pathway through the insular cortex (IC), as well as heart rate variability (HRV) in relation to Osteopathic Manipulative Therapy (OMT) and deep-touch. Aims: The present study investigated whether both OMT treatment and deep-touch (a newly hypothesized treatment option) was effective at altering the interoceptive pathway and HRV, whilst OMT was only expected to be effective for increasing Range of Motion (ROM). Methods: Thirty-five healthy volunteers were randomly allocated into three conditions in a repeated measures crossover design; a control (laying supine on a plinth); deep-touch (head cradling); and an osteopathic mobilization therapeutic technique on the temporomandibular joint (TMJ). Interoceptive accuracy (IAc), HRV, as well as range of motion (ROM) for the TMJ area as well as the cervical spine (Csp) right and left measures were taken pre and post each condition setting. Results: Significant condition effects emerged from the deep-touch and mobilization interventions for IAc where increases were identified through planned comparisons. For the HRV measure (RMSSD), a significant effect emerged in the deep-touch condition (increase) but not in the mobilization or control conditions. ROM did not increase for any condition. IAc correlated with post-ROM outcomes in many cases and HRV moderated some of these relations. Conclusion: These results are discussed in the context of clinical practice, where cranial deep-touch maybe an effective treatment and modulator of the parasympathetic nervous systems, as well as the interoceptive system.
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Affiliation(s)
- Darren J Edwards
- Department of Interprofessional Health Studies, Swansea University, Swansea, United Kingdom
| | - Hayley Young
- Department of Psychology, Swansea University, Swansea, United Kingdom
| | - Annabel Cutis
- Department of Interprofessional Health Studies, Swansea University, Swansea, United Kingdom
| | - Ross Johnston
- Department of Interprofessional Health Studies, Swansea University, Swansea, United Kingdom
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32
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Delhaye BP, Long KH, Bensmaia SJ. Neural Basis of Touch and Proprioception in Primate Cortex. Compr Physiol 2018; 8:1575-1602. [PMID: 30215864 PMCID: PMC6330897 DOI: 10.1002/cphy.c170033] [Citation(s) in RCA: 108] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The sense of proprioception allows us to keep track of our limb posture and movements and the sense of touch provides us with information about objects with which we come into contact. In both senses, mechanoreceptors convert the deformation of tissues-skin, muscles, tendons, ligaments, or joints-into neural signals. Tactile and proprioceptive signals are then relayed by the peripheral nerves to the central nervous system, where they are processed to give rise to percepts of objects and of the state of our body. In this review, we first examine briefly the receptors that mediate touch and proprioception, their associated nerve fibers, and pathways they follow to the cerebral cortex. We then provide an overview of the different cortical areas that process tactile and proprioceptive information. Next, we discuss how various features of objects-their shape, motion, and texture, for example-are encoded in the various cortical fields, and the susceptibility of these neural codes to attention and other forms of higher-order modulation. Finally, we summarize recent efforts to restore the senses of touch and proprioception by electrically stimulating somatosensory cortex. © 2018 American Physiological Society. Compr Physiol 8:1575-1602, 2018.
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Affiliation(s)
- Benoit P Delhaye
- Department of Organismal Biology and Anatomy, University of Chicago, Chicago, USA
| | - Katie H Long
- Committee on Computational Neuroscience, University of Chicago, Chicago, USA
| | - Sliman J Bensmaia
- Department of Organismal Biology and Anatomy, University of Chicago, Chicago, USA.,Committee on Computational Neuroscience, University of Chicago, Chicago, USA
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33
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A touch-scaffolded model of human prosociality. Neurosci Biobehav Rev 2018; 92:453-463. [DOI: 10.1016/j.neubiorev.2018.07.008] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2017] [Revised: 05/21/2018] [Accepted: 07/11/2018] [Indexed: 01/10/2023]
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34
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Dissociable sources of erogeneity in social touch: Imagining and perceiving C-Tactile optimal touch in erogenous zones. PLoS One 2018; 13:e0203039. [PMID: 30142185 PMCID: PMC6108496 DOI: 10.1371/journal.pone.0203039] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2018] [Accepted: 08/14/2018] [Indexed: 12/13/2022] Open
Abstract
Previous research points to two major hypotheses regarding the mechanisms by which touch can be experienced as erotogenic. The first concerns the body part to which touch is applied (erogenous zones) and the second the modality of touch (sensual touch optimal in activating C Tactile afferents). In this study, we explored for the first time the relation between those two mechanisms in actual and imagined social touch. In a first experiment, we randomly assigned “Giver” and “Receiver” roles within 19 romantic couples (20 females, 18 males, age 32.34 ± 8.71SD years) and asked the “Giver” to apply CT-optimal (3 cm/s) vs. CT-suboptimal (18 cm/s) touch on an erogenous (neck) vs. non-erogenous zone (forehead) of their partner. We then obtained ratings of pleasantness and sexual arousal from both “Receivers” and “Givers”. In a second experiment, 32 healthy females (age 25.16 ± 5.91SD years) were asked to imagine CT-optimal vs. CT-suboptimal stimulation (stroking vs. patting) and velocity (3 cm/s vs. 18 cm/s) on different erogenous vs. non-erogenous zones and rate pleasantness. While both erogenous body part and CT-optimal, sensual touch were found to increase pleasant and erotic sensations, the results showed a lack of an interaction. Furthermore, pleasantness was induced by mere imagination of touch without any tactile stimulation, and touch that was sexually arousing for the receiver was rated as more sexually arousing for the giver as well, pointing to top-down, learned expectations of sensory pleasure and erogeneity. Taken together, these studies provide the first direct evidence that while both the body location to which touch is applied and the mode of touch contribute to pleasant and erotic sensations, these two factors appear to mediate subjective pleasantness and erogeneity by, at least partly, independent mechanisms.
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35
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The right touch: Stroking of CT-innervated skin promotes vocal emotion processing. COGNITIVE AFFECTIVE & BEHAVIORAL NEUROSCIENCE 2018; 17:1129-1140. [PMID: 28933047 PMCID: PMC5709431 DOI: 10.3758/s13415-017-0537-5] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Research has revealed a special mechanoreceptor, called C-tactile (CT) afferent, that is situated in hairy skin and that seems relevant for the processing of social touch. We pursued a possible role of this receptor in the perception of other social signals such as a person’s voice. Participants completed three sessions in which they heard surprised and neutral vocal and nonvocal sounds and detected rare sound repetitions. In a given session, participants received no touch or soft brushstrokes to the arm (CT innervated) or palm (CT free). Event-related potentials elicited to sounds revealed that stroking to the arm facilitated the integration of vocal and emotional information. The late positive potential was greater for surprised vocal relative to neutral vocal and nonvocal sounds, and this effect was greater for arm touch relative to both palm touch and no touch. Together, these results indicate that stroking to the arm facilitates the allocation of processing resources to emotional voices, thus supporting the possibility that CT stimulation benefits social perception cross-modally.
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36
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Fu Y, Selcuk E, Moore SR, Depue RA. Touch-induced face conditioning is mediated by genetic variation in opioid but not oxytocin receptors. Sci Rep 2018; 8:9004. [PMID: 29899398 PMCID: PMC5998070 DOI: 10.1038/s41598-018-27199-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2018] [Accepted: 05/15/2018] [Indexed: 12/26/2022] Open
Abstract
Soft touch possesses strong prosocial effects that facilitate social bonding and group cohesion in animals. Touch activates opioids (OP) and oxytocin (OXT), two neuromodulators involved in affiliative behaviors and social bonding. We examined whether touch serves as an unconditioned reward in affective conditioning of human faces, a basic process in social bonding, and whether this process is mediated by variation in mu-OP (OPRM1) and OXT (rs53576) receptor genes. Participants viewed affectively-neutral human faces, half of which were paired with a brief soft brushing on the forearm as an unconditioned stimulus (US). Paired and unpaired faces were rated for positive affective and sensory features of touch. Variation in OPRM1 but not rs53576 significantly modulated strength and development of conditioning, indicating that touch-induced mu-OP but not OXT activity provides rewarding properties of a US in conditioning. Implications for touch-induced mu-OP activity in normal and disordered conditioned social bonding are discussed.
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MESH Headings
- Analgesics, Opioid/metabolism
- Conditioning, Operant/physiology
- Face/physiology
- Female
- Genotype
- Humans
- Male
- Oxytocin/metabolism
- Photic Stimulation
- Receptors, Opioid, mu/genetics
- Receptors, Opioid, mu/metabolism
- Receptors, Opioid, mu/physiology
- Receptors, Oxytocin/genetics
- Receptors, Oxytocin/metabolism
- Receptors, Oxytocin/physiology
- Reward
- Social Behavior
- Touch/physiology
- Young Adult
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Affiliation(s)
- Yu Fu
- Department of Human Development and Institute of Human Neuroscience, Cornell University, Ithaca, New York, 14850, USA
| | - Emre Selcuk
- Department of Human Development and Institute of Human Neuroscience, Cornell University, Ithaca, New York, 14850, USA
- Department of Psychology, Middle East Technical University, Ankara, 06800, Turkey
| | - Sarah R Moore
- Department of Human Development and Institute of Human Neuroscience, Cornell University, Ithaca, New York, 14850, USA
| | - Richard A Depue
- Department of Human Development and Institute of Human Neuroscience, Cornell University, Ithaca, New York, 14850, USA.
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37
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Riquelme I, Hatem SM, Montoya P. Reduction of Pain Sensitivity after Somatosensory Therapy in Children with Autism Spectrum Disorders. JOURNAL OF ABNORMAL CHILD PSYCHOLOGY 2018; 46:1731-1740. [DOI: 10.1007/s10802-017-0390-6] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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38
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Etzi R, Carta C, Gallace A. Stroking and tapping the skin: behavioral and electrodermal effects. Exp Brain Res 2017; 236:453-461. [DOI: 10.1007/s00221-017-5143-9] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2017] [Accepted: 12/03/2017] [Indexed: 12/28/2022]
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39
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Miguel HO, Lisboa IC, Gonçalves ÓF, Sampaio A. Brain mechanisms for processing discriminative and affective touch in 7-month-old infants. Dev Cogn Neurosci 2017; 35:20-27. [PMID: 29108882 PMCID: PMC6968955 DOI: 10.1016/j.dcn.2017.10.008] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2017] [Revised: 10/13/2017] [Accepted: 10/20/2017] [Indexed: 12/20/2022] Open
Abstract
Affective touch has been associated with affiliative behavior during early stages of infant development; however, its underlying brain mechanisms are still poorly understood. This study used fNIRS (functional near-infrared spectroscopy) to examine both affective and discriminative touch in 7- month-old infants (n=35). Infants were provided affective stimuli on the forearm for 10 sec followed by a 20 sec rest period. The protocol was repeated for discriminative touch, and both affective and discriminative stimuli were given in a counterbalanced order. Brain activation (oxy-hemoglobin and deoxy-hemoglobin levels) in the somatosensory and temporal regions was registered during administration of the stimuli. There was an increase in oxy-hemoglobin and decrease in deoxy-hemoglobin only in the somatosensory region in response to both affective and discriminative touch. No other activations were found. Seven-month-old infants’ brain activation in the somatosensory cortex was similar for both discriminative and affective touch, but the stimuli did not elicit any activation in the temporal region/ pSTS. Our study is the first to suggest that 7-month-old infants do not yet recruit socio-emotional brain areas in response to affective touch.
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Affiliation(s)
- Helga O Miguel
- Neuropsychophysiology Lab, CiPsi, School of Psychology, University of Minho, Campus de Gualtar, 4710-057 Braga, Portugal.
| | - Isabel C Lisboa
- Human Cognition Lab, CiPsi, School of Psychology, University of Minho, Campus de Gualtar, 4710-057 Braga, Portugal.
| | - Óscar F Gonçalves
- Neuropsychophysiology Lab, CiPsi, School of Psychology, University of Minho, Campus de Gualtar, 4710-057 Braga, Portugal; Spaulding Neuromodulation Center, Spaulding Rehabilitation Hospital, Harvard Medical School, Charlestown campus: 79/96 13th Street, Charlestown, MA, 02129, USA.
| | - Adriana Sampaio
- Neuropsychophysiology Lab, CiPsi, School of Psychology, University of Minho, Campus de Gualtar, 4710-057 Braga, Portugal.
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40
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Pacchierotti C, Sinclair S, Solazzi M, Frisoli A, Hayward V, Prattichizzo D. Wearable Haptic Systems for the Fingertip and the Hand: Taxonomy, Review, and Perspectives. IEEE TRANSACTIONS ON HAPTICS 2017; 10:580-600. [PMID: 28500008 DOI: 10.1109/toh.2017.2689006] [Citation(s) in RCA: 167] [Impact Index Per Article: 23.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
In the last decade, we have witnessed a drastic change in the form factor of audio and vision technologies, from heavy and grounded machines to lightweight devices that naturally fit our bodies. However, only recently, haptic systems have started to be designed with wearability in mind. The wearability of haptic systems enables novel forms of communication, cooperation, and integration between humans and machines. Wearable haptic interfaces are capable of communicating with the human wearers during their interaction with the environment they share, in a natural and yet private way. This paper presents a taxonomy and review of wearable haptic systems for the fingertip and the hand, focusing on those systems directly addressing wearability challenges. The paper also discusses the main technological and design challenges for the development of wearable haptic interfaces, and it reports on the future perspectives of the field. Finally, the paper includes two tables summarizing the characteristics and features of the most representative wearable haptic systems for the fingertip and the hand.
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41
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A positive touch: C-tactile afferent targeted skin stimulation carries an appetitive motivational value. Biol Psychol 2017; 129:186-194. [DOI: 10.1016/j.biopsycho.2017.08.057] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2017] [Revised: 07/25/2017] [Accepted: 08/29/2017] [Indexed: 12/29/2022]
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42
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Heart rate variability is enhanced by long-lasting pleasant touch at CT-optimized velocity. Biol Psychol 2017; 128:71-81. [DOI: 10.1016/j.biopsycho.2017.07.007] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2016] [Revised: 07/10/2017] [Accepted: 07/12/2017] [Indexed: 11/23/2022]
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43
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Autonomic versus perceptual accounts for tactile hypersensitivity in autism spectrum disorder. Sci Rep 2017; 7:8259. [PMID: 28811601 PMCID: PMC5557757 DOI: 10.1038/s41598-017-08730-3] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2017] [Accepted: 07/17/2017] [Indexed: 12/27/2022] Open
Abstract
Tactile atypicality in individuals with autism spectrum disorder (ASD) has harmful effects on their everyday lives including social interactions. However, whether tactile atypicality in ASD reflects perceptual and/or autonomic processes is unknown. Here, we show that adults with ASD have hypersensitivity to tactile stimuli in the autonomic but not perceptual domain. In particular, adults with ASD showed a greater skin conductance response (SCR) to tactile stimuli compared to typically developing (TD) adults, despite an absence of differences in subjective responses. Furthermore, the level of the SCR was correlated with sensory sensitivity in daily living. By contrast, in perceptual discriminative tasks that psychophysically measured thresholds to tactile stimuli, no differences were found between the ASD and TD groups. These results favor the hypothesis that atypical autonomic processing underlies tactile hypersensitivity in ASD.
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44
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Henning M, Fox GR, Kaplan J, Damasio H, Damasio A. A Potential Role for mu-Opioids in Mediating the Positive Effects of Gratitude. Front Psychol 2017; 8:868. [PMID: 28680408 PMCID: PMC5478726 DOI: 10.3389/fpsyg.2017.00868] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2016] [Accepted: 05/11/2017] [Indexed: 12/19/2022] Open
Abstract
Gratitude is a complex emotional feeling associated with universally desirable positive effects in personal, social, and physiological domains. Why or how gratitude achieves these functional outcomes is not clear. Toward the goal of identifying its' underlying physiological processes, we recently investigated the neural correlates of gratitude. In our study, participants were exposed to gratitude-inducing stimuli, and rated each according to how much gratitude it provoked. As expected, self-reported gratitude intensity correlated with brain activity in distinct regions of the medial pre-frontal cortex associated with social reward and moral cognition. Here we draw from our data and existing literature to offer a theoretical foundation for the physiological correlates of gratitude. We propose that mu-opioid signaling (1) accompanies the mental experience of gratitude, and (2) may account for the positive effects of gratitude on social relationships, subjective wellbeing, and physiological health.
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Affiliation(s)
- Max Henning
- Psychology, Brain and Creativity Institute, University of Southern CaliforniaLos Angeles, CA, United States.,Performance Science Institute, University of Southern CaliforniaLos Angeles, CA, United States
| | - Glenn R Fox
- Psychology, Brain and Creativity Institute, University of Southern CaliforniaLos Angeles, CA, United States.,Performance Science Institute, University of Southern CaliforniaLos Angeles, CA, United States
| | - Jonas Kaplan
- Psychology, Brain and Creativity Institute, University of Southern CaliforniaLos Angeles, CA, United States
| | - Hanna Damasio
- Psychology, Brain and Creativity Institute, University of Southern CaliforniaLos Angeles, CA, United States
| | - Antonio Damasio
- Psychology, Brain and Creativity Institute, University of Southern CaliforniaLos Angeles, CA, United States
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45
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Pawling R, Cannon PR, McGlone FP, Walker SC. C-tactile afferent stimulating touch carries a positive affective value. PLoS One 2017; 12:e0173457. [PMID: 28282451 PMCID: PMC5345811 DOI: 10.1371/journal.pone.0173457] [Citation(s) in RCA: 129] [Impact Index Per Article: 18.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2016] [Accepted: 02/22/2017] [Indexed: 12/23/2022] Open
Abstract
The rewarding sensation of touch in affiliative interactions is hypothesized to be underpinned by a specialized system of nerve fibers called C-Tactile afferents (CTs), which respond optimally to slowly moving, gentle touch, typical of a caress. However, empirical evidence to support the theory that CTs encode socially relevant, rewarding tactile information in humans is currently limited. While in healthy participants, touch applied at CT optimal velocities (1-10cm/sec) is reliably rated as subjectively pleasant, neuronopathy patients lacking large myelinated afferents, but with intact C-fibres, report that the conscious sensation elicited by stimulation of CTs is rather vague. Given this weak perceptual impact the value of self-report measures for assessing the specific affective value of CT activating touch appears limited. Therefore, we combined subjective ratings of touch pleasantness with implicit measures of affective state (facial electromyography) and autonomic arousal (heart rate) to determine whether CT activation carries a positive affective value. We recorded the activity of two key emotion-relevant facial muscle sites (zygomaticus major—smile muscle, positive affect & corrugator supercilii—frown muscle, negative affect) while participants evaluated the pleasantness of experimenter administered stroking touch, delivered using a soft brush, at two velocities (CT optimal 3cm/sec & CT non-optimal 30cm/sec), on two skin sites (CT innervated forearm & non-CT innervated palm). On both sites, 3cm/sec stroking touch was rated as more pleasant and produced greater heart rate deceleration than 30cm/sec stimulation. However, neither self-report ratings nor heart rate responses discriminated stimulation on the CT innervated arm from stroking of the non-CT innervated palm. In contrast, significantly greater activation of the zygomaticus major (smiling muscle) was seen specifically to CT optimal, 3cm/sec, stroking on the forearm in comparison to all other stimuli. These results offer the first empirical evidence in humans that tactile stimulation that optimally activates CTs carries a positive affective valence that can be measured implicitly.
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Affiliation(s)
- Ralph Pawling
- Research Centre for Brain & Behaviour, School of Natural Sciences & Psychology, Liverpool John Moores University, Liverpool, United Kingdom
| | - Peter R. Cannon
- School of Psychology, Massey University, Auckland, New Zealand
| | - Francis P. McGlone
- Research Centre for Brain & Behaviour, School of Natural Sciences & Psychology, Liverpool John Moores University, Liverpool, United Kingdom
- Institute of Psychology, Health & Society, University of Liverpool, Liverpool, United Kingdom
| | - Susannah C. Walker
- Research Centre for Brain & Behaviour, School of Natural Sciences & Psychology, Liverpool John Moores University, Liverpool, United Kingdom
- * E-mail:
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Greco A, Valenza G, Scilingo EP. Investigating mechanical properties of a fabric-based affective haptic display through electrodermal activity analysis. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2017; 2016:407-410. [PMID: 28268359 DOI: 10.1109/embc.2016.7590726] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The aim of this study is the development of a classification system able to discern between two levels of velocity of a caress-like haptic stimulus, through information gathered from the analysis of the Electrodermal Activity (EDA) dynamics. We designed and performed an experiment where EDA signals were acquired during caress-like stimuli conveyed to 32 healthy volunteers (16 females) by means of four different fabrics (hemp, burlap, velvet and silk) and at two velocity levels (9.4 mm/s and 65 mm/s). CvxEDA model was used to process the EDA signal and extract features from both tonic and phasic components. The feature set was used as an input to a K-NN classifier implementing a leave-one-subject-out procedure. Considering all fabrics, results show an accuracy of velocity recognition between 91.07% and 96.43%. Conversely, poor accuracy was achieved considering the fabric classification. Results also suggest that caress velocity significantly affects EDA dynamics regardless of the typology of fabrics. This is probably due to the fact that velocity is strictly related to the valence of the affective stimuli.
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McGlone F, Cerritelli F, Walker S, Esteves J. The role of gentle touch in perinatal osteopathic manual therapy. Neurosci Biobehav Rev 2016; 72:1-9. [PMID: 27845175 DOI: 10.1016/j.neubiorev.2016.11.009] [Citation(s) in RCA: 56] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2016] [Revised: 09/22/2016] [Accepted: 11/09/2016] [Indexed: 12/31/2022]
Abstract
Osteopathic medicine is a system of manual diagnosis and treatment. While there is growing evidence that osteopathy is effective in a range of clinical conditions, the underlying biological basis of its therapeutic effects remain largely unknown. Given that the sense of touch plays a critical role in osteopathy, in this perspective article, with a particular focus on perinatal care, we explore the potential mechanisms by which stimulation of the skin senses can exert beneficial physiological and psychological effects, aiding growth and development. We propose that a class of low threshold mechanosensitive c-fibre, named c-tactile afferents, which respond optimally to gentle, slow moving touch are likely to play a direct and significant role in the efficacy of manual therapies. A greater understanding of the impact the type and quality of touch plays in therapeutic tactile interventions and in particular the neuroscience underpinning these effects will aid the development of more targeted, population specific interventions.
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Affiliation(s)
- Francis McGlone
- Research Centre for Brain & Behaviour, School of Natural Sciences & Psychology, Liverpool John Moores University, Liverpool, L3 3AF, UK; Institute of Psychology, Health and Society, University of Liverpool, UK.
| | - Francesco Cerritelli
- Department of Neuroscience and Imaging, University of Chieti-Pescara, Italy; Clinical-based Human Research Department, Centre for Osteopathic Medicine Collaboration, Pescara, Italy.
| | - Susannah Walker
- Research Centre for Brain & Behaviour, School of Natural Sciences & Psychology, Liverpool John Moores University, Liverpool, L3 3AF, UK.
| | - Jorge Esteves
- British School of Osteopathy, London, UK; Clinical-based Human Research Department, Centre for Osteopathic Medicine Collaboration, Pescara, Italy; Instituto Piaget, Lisbon, Portugal.
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Sailer U, Triscoli C, Häggblad G, Hamilton P, Olausson H, Croy I. Temporal dynamics of brain activation during 40 minutes of pleasant touch. Neuroimage 2016; 139:360-367. [DOI: 10.1016/j.neuroimage.2016.06.031] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2016] [Revised: 05/16/2016] [Accepted: 06/17/2016] [Indexed: 10/21/2022] Open
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Grandi LC. From Sweeping to the Caress: Similarities and Discrepancies between Human and Non-Human Primates' Pleasant Touch. Front Psychol 2016; 7:1371. [PMID: 27660620 PMCID: PMC5014988 DOI: 10.3389/fpsyg.2016.01371] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2016] [Accepted: 08/29/2016] [Indexed: 01/27/2023] Open
Abstract
Affective touch plays a key role in affiliative behavior, offering a mechanism for the formation and maintenance of social bonds among conspecifics, both in humans and non-human primates. Furthermore, it has been speculated that the CT fiber system is a specific coding channel for affiliative touch that occurs during skin-to-skin interactions with conspecifics. In humans, this touch is commonly referred to as the caress, and its correlation with the CT fiber system has been widely demonstrated. It has been hypothesized that the sweeping touch that occurs during grooming in non-human primates may modulate the CT fibers, with recent preliminary studies on rhesus monkeys supporting this hypothesis. The present mini-review proposes a comparison between the pleasant touch, caress and sweeping of humans and non-human primates, respectively. The currently available data was therefore reviewed regarding (i) the correlation between pleasant touch and CT fibers both in humans and non-human primates, (ii) the autonomic effects, (iii) the encoding at the central nervous system, (iv) the development from early life to adulthood, and (v) the potential applications of pleasant touch in the daily lives of both humans and non-human primates. Moreover, by considering both the similarities and discrepancies between the human caress and non-human primate sweeping, a possible evolutionary mechanism can be proposed that has developed from sweeping as a utilitarian action with affiliative meaning among monkeys, to the caress as a purely affective gesture associated with humans.
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