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Nature Reviews. Neuroscience Sep 2021Our sense of touch emerges from an array of mechanosensory structures residing within the fabric of our skin. These tactile end organ structures convert innocuous forces... (Review)
Review
Our sense of touch emerges from an array of mechanosensory structures residing within the fabric of our skin. These tactile end organ structures convert innocuous forces acting on the skin into electrical signals that propagate to the CNS via the axons of low-threshold mechanoreceptors (LTMRs). Our rich capacity for tactile discrimination arises from the dissimilar intrinsic properties of the LTMR subtypes that innervate different regions of the skin and the structurally distinct end organ complexes with which they associate. These end organ structures comprise a range of non-neuronal cell types, which may themselves actively contribute to the transformation of tactile forces into neural impulses within the LTMR afferents. Although the mechanism and the site of transduction across end organs remain unclear, PIEZO2 has emerged as the principal mechanosensitive channel involved in light touch of the skin. Here we review the physiological properties of LTMR subtypes and discuss how features of their cutaneous end organ complexes shape subtype-specific tuning.
Topics: Animals; Humans; Mechanoreceptors; Skin; Touch
PubMed: 34312536
DOI: 10.1038/s41583-021-00489-x -
Neuron Aug 2013The somatosensory system decodes a wide range of tactile stimuli and thus endows us with a remarkable capacity for object recognition, texture discrimination,... (Review)
Review
The somatosensory system decodes a wide range of tactile stimuli and thus endows us with a remarkable capacity for object recognition, texture discrimination, sensory-motor feedback and social exchange. The first step leading to perception of innocuous touch is activation of cutaneous sensory neurons called low-threshold mechanoreceptors (LTMRs). Here, we review the properties and functions of LTMRs, emphasizing the unique tuning properties of LTMR subtypes and the organizational logic of their peripheral and central axonal projections. We discuss the spinal cord neurophysiological representation of complex mechanical forces acting upon the skin and current views of how tactile information is processed and conveyed from the spinal cord to the brain. An integrative model in which ensembles of impulses arising from physiologically distinct LTMRs are integrated and processed in somatotopically aligned mechanosensory columns of the spinal cord dorsal horn underlies the nervous system's enormous capacity for perceiving the richness of the tactile world.
Topics: Animals; Mechanoreceptors; Physical Stimulation; Sensory Receptor Cells; Sensory Thresholds; Touch
PubMed: 23972592
DOI: 10.1016/j.neuron.2013.07.051 -
Developmental Cognitive Neuroscience Feb 2019Social touch is a powerful force in human development, shaping social reward, attachment, cognitive, communication, and emotional regulation from infancy and throughout... (Review)
Review
Social touch is a powerful force in human development, shaping social reward, attachment, cognitive, communication, and emotional regulation from infancy and throughout life. In this review, we consider the question of how social touch is defined from both bottom-up and top-down perspectives. In the former category, there is a clear role for the C-touch (CT) system, which constitutes a unique submodality that mediates affective touch and contrasts with discriminative touch. Top-down factors such as culture, personal relationships, setting, gender, and other contextual influences are also important in defining and interpreting social touch. The critical role of social touch throughout the lifespan is considered, with special attention to infancy and young childhood, a time during which social touch and its neural, behavioral, and physiological contingencies contribute to reinforcement-based learning and impact a variety of developmental trajectories. Finally, the role of social touch in an example of disordered development -autism spectrum disorder-is reviewed.
Topics: Female; Human Development; Humans; Male; Touch
PubMed: 29731417
DOI: 10.1016/j.dcn.2018.04.009 -
PloS One 2021Recent evidence suggests that altered responses to affective touch-a pleasant interoceptive stimulus associated with activation of the C-Tactile (CT) system-may...
Recent evidence suggests that altered responses to affective touch-a pleasant interoceptive stimulus associated with activation of the C-Tactile (CT) system-may contribute to the aetiology and maintenance of mental conditions characterised by body image disturbances (e.g., Anorexia Nervosa). Here, we investigated whether tactile pleasantness and intensity differ across body sites, and if individual differences in dysmorphic appearance concerns and body and emotional awareness might be associated with touch perceptions across body sites. To this end, we measured perceived pleasantness and intensity of gentle, dynamic stroking touches applied to the palm, forearm, face, abdomen and back of 30 female participants (mean age: 25.87±1.17yrs) using CT-optimal (3 cm/s) and non-CT optimal (0.3 and 30 cm/s) stroking touch. As expected, participants rated CT-targeted touch as more pleasant compared to the two non-CT optimal stroking touch at all body sites. Regardless of stroking velocity, touch applied to the abdomen elicited the lowest pleasantness ratings. Lower levels of emotional awareness, greater levels of interoceptive sensibility and of dysmorphic concerns were associated with lower preference for CT-optimal stroking touch applied to the forearm and the back. These findings begin to elucidate the link between CT sensitivity, dysmorphic appearance concerns and body and emotional awareness, which may have implications for future research looking to inform early interventions. Addressing impaired processing of affective interoceptive stimuli, such as CT-targeted touch, may be the key to current treatment approaches available for those populations at risk of disorders characterised by body image disturbance.
Topics: Adult; Affect; Body Image; Emotions; Female; Humans; Male; Physical Stimulation; Touch; Touch Perception; Young Adult
PubMed: 34818341
DOI: 10.1371/journal.pone.0243680 -
Current Opinion in Neurobiology Apr 2022Social touch-the affiliative skin-to-skin contact between individuals-can rapidly evoke emotions of comfort, pleasure, or calm, and is essential for mental and physical... (Review)
Review
Social touch-the affiliative skin-to-skin contact between individuals-can rapidly evoke emotions of comfort, pleasure, or calm, and is essential for mental and physical well-being. Physical isolation from social support can be devastating. During the COVID-19 pandemic, we observed a global increase in suicidal ideation, anxiety, domestic violence, and worsening of pre-existing physical conditions, alerting society to our need to understand the neurobiology of social touch and how it promotes normal health. Gaining a mechanistic understanding of how sensory neuron stimulation induces pleasure, calm, and analgesia may reveal untapped therapeutic targets in the periphery for treatment of anxiety and depression, as well as social disorders and traumas in which social touch becomes aversive. Bridging the gap between stimulation in the skin and positive affect in the brain-especially during naturally occurring social touch behaviors-remains a challenge to the field. However, with advances in mouse genetics, behavioral quantification, and brain imaging approaches to measure neuronal firing and neurochemical release, completing this mechanistic picture may be on the horizon. Here, we summarize some exciting new findings about social touch in mammals, emphasizing both the peripheral and central nervous systems, with attempts to bridge the gap between external stimulation and internal representations in the brain.
Topics: Animals; Brain; Humans; Mice; Pleasure; Social Behavior; Touch
PubMed: 35453001
DOI: 10.1016/j.conb.2022.102527 -
International Journal of Environmental... Feb 2023To combat the spread of the COVID-19, regulations were introduced to limit physical interactions. This could induce a longing for touch in the general population and...
To combat the spread of the COVID-19, regulations were introduced to limit physical interactions. This could induce a longing for touch in the general population and subsequently impact social, psychological, physical and environmental quality of life (QoL). The aim of this study was to investigate the potential association between COVID-19 regulations, longing for touch and QoL. A total of 1978 participants from different countries completed an online survey, including questions about their general wellbeing and the desire to be touched. In our sample, 83% of participants reported a longing for touch. Longing for touch was subsequently associated with a lower physical, psychological and social QoL. No association was found with environmental QoL. These findings highlight the importance of touch for QoL and suggest that the COVID-19 regulations have concurrent negative consequences for the wellbeing of the general population.
Topics: Humans; Touch; Quality of Life; Pandemics; COVID-19; Touch Perception
PubMed: 36900866
DOI: 10.3390/ijerph20053855 -
Frontiers in Neural Circuits 2022Mate choice is a potent generator of diversity and a fundamental pillar for sexual selection and evolution. Mate choice is a multistage affair, where complex sensory... (Review)
Review
Mate choice is a potent generator of diversity and a fundamental pillar for sexual selection and evolution. Mate choice is a multistage affair, where complex sensory information and elaborate actions are used to identify, scrutinize, and evaluate potential mating partners. While widely accepted that communication during mate assessment relies on multimodal cues, most studies investigating the mechanisms controlling this fundamental behavior have restricted their focus to the dominant sensory modality used by the species under examination, such as vision in humans and smell in rodents. However, despite their undeniable importance for the initial recognition, attraction, and approach towards a potential mate, other modalities gain relevance as the interaction progresses, amongst which are touch and audition. In this review, we will: (1) focus on recent findings of how touch and audition can contribute to the evaluation and choice of mating partners, and (2) outline our current knowledge regarding the neuronal circuits processing touch and audition (amongst others) in the context of mate choice and ask (3) how these neural circuits are connected to areas that have been studied in the light of multisensory integration.
Topics: Auditory Perception; Hearing; Humans; Smell; Touch; Touch Perception
PubMed: 36247731
DOI: 10.3389/fncir.2022.943888 -
Current Opinion in Neurobiology Jun 2022The sense of touch is ubiquitous in vertebrates and relies upon the detection of mechanical forces in the skin by the tactile end-organs of low-threshold... (Review)
Review
The sense of touch is ubiquitous in vertebrates and relies upon the detection of mechanical forces in the skin by the tactile end-organs of low-threshold mechanoreceptors. Significant progress has been made in understanding the mechanism of tactile end-organ function using mammalian models, but the detailed mechanics of touch sensation in Meissner and Pacinian corpuscles, the principal detectors of transient touch and vibration, remain obscure. The avian homologs of these corpuscles present an opportunity for functional study of mechanosensation in these structures, due to their relative accessibility and high abundance in the bill skin of tactile-foraging waterfowl. Here, we review the current knowledge of mechanosensory end-organs in birds and highlight the utility of the avian model to understand general principles of touch detection in the glabrous skin of vertebrates.
Topics: Animals; Birds; Mammals; Mechanoreceptors; Skin; Touch; Touch Perception; Vertebrates
PubMed: 35489134
DOI: 10.1016/j.conb.2022.102548 -
Neuroscience and Biobehavioral Reviews Dec 2021Social touch is increasingly utilized in a variety of psychological interventions, ranging from parent-child interventions to psychotherapeutic treatments. Less... (Review)
Review
Social touch is increasingly utilized in a variety of psychological interventions, ranging from parent-child interventions to psychotherapeutic treatments. Less attention has been paid, however, to findings that exposure to social touch may not necessarily evoke positive or pleasant responses. Social touch can convey different emotions from love and gratitude to harassment and envy, and persons' preferences to touch and be touched do not necessarily match with each other. This review of altogether 99 original studies focuses on how contextual factors modify target person's behavioral and brain responses to social touch. The review shows that experience of social touch is strongly modified by a variety of toucher-related and situational factors: for example, toucher's facial expressions, physical attractiveness, relationship status, group membership, and touched person's psychological distress. At the neural level, contextual factors modify processing of social touch from early perceptual processing to reflective cognitive evaluation. Based on the review, we present implications for using social touch in behavioral and neuroscientific research designs.
Topics: Attention; Emotions; Facial Expression; Humans; Touch; Touch Perception
PubMed: 34537266
DOI: 10.1016/j.neubiorev.2021.09.027 -
Journal of Neurophysiology Oct 2021Besides providing information on elementary properties of objects, like texture, roughness, and softness, the sense of touch is also important in building a... (Review)
Review
Besides providing information on elementary properties of objects, like texture, roughness, and softness, the sense of touch is also important in building a representation of object movement and the movement of our hands. Neural and behavioral studies shed light on the mechanisms and limits of our sense of touch in the perception of texture and motion, and of its role in the control of movement of our hands. The interplay between the geometrical and mechanical properties of the touched objects, such as shape and texture, the movement of the hand exploring the object, and the motion felt by touch, will be discussed in this article. Interestingly, the interaction between motion and textures can generate perceptual illusions in touch. For example, the orientation and the spacing of the texture elements on a static surface induces the illusion of surface motion when we move our hand on it or can elicit the perception of a curved trajectory during sliding, straight hand movements. In this work we present a multiperspective view that encompasses both the perceptual and the motor aspects, as well as the response of peripheral and central nerve structures, to analyze and better understand the complex mechanisms underpinning the tactile representation of texture and motion. Such a better understanding of the spatiotemporal features of the tactile stimulus can reveal novel transdisciplinary applications in neuroscience and haptics.
Topics: Humans; Illusions; Motion Perception; Somatosensory Cortex; Touch; Touch Perception
PubMed: 34495782
DOI: 10.1152/jn.00583.2020