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PubMed1993

Relationships between touch sensations and estimated population responses of peripheral afferent mechanoreceptors.

Trapezoidal indentations of the skin by a 0.5-mm-diameter probe were presented at different rates and loads (forces) to the human fingertip, in order to compare estimates of population responses of cutaneous mechanoreceptors with the quality and magnitude of tactile sensations. The subjects were first trained to attend to and evaluate variations in the magnitude of touch sensations associated with the onset ramp, the plateau period, and the offset ramp. They examined a series of line drawings that illustrated a variety of temporal profiles for sensation magnitude. The line drawings provided a straight-forward means of describing temporal fluctuations of sensation intensity, which corresponded well to psychophysical ratios that were determined subsequently with a matching procedure. Influences of ramp rate on qualities of touch sensations were evaluated by tabulating verbal descriptions of sensory experiences. Each of three rate conditions generated a different quality of sensation during the dynamic portions of stimulation. Onsets and offsets at 100 g/s were described as "taps". During ramps at 10 g/s the quality was described as "rolling" or "moving". At 1 g/s no sense of motion was detected; instead, a "pressure" sensation was identified. Touch sensations during the plateau were always described as a pressure. The subjective magnitudes of touch sensations associated with the onset, plateau, and offset were equated by comparing different components of paired stimuli. At 100 g/s, when subjects matched the offset sensation from the first of a pair of stimuli with the onset sensation from the second, the force of the stimulus producing the offset sensation was 1.3 times greater than the intensity of the stimulus that produced the onset sensation. Matching of the plateau sensation (evaluated during the last 1.5 s of the 2.5-s plateau period) with the onset sensation required a plateau stimulus that was 1.7 times greater in force than the stimulus which produced the onset. Comparison of stimulus intensities producing a match of plateau and offset sensations with stimulus intensities predicted from the previous matches (onset versus offset and onset versus plateau) demonstrated a mean within-subject error of 4%. The mean ratio of plateau to offset forces that produced a match was 1.8:1.3. In a matching procedure in which subjects compared the subjective magnitudes of plateau sensations following onset ramps of different rates, onset ramp rate significantly influenced the magnitude of pressure sensations. The ratios of plateau forces which produced equal magnitudes of sensation following 1, 10, and 100 g/s ramps were 1.6:1.3:1.0.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗
PubMed2005

Attentional demands associated with the use of a light fingertip touch for postural control during quiet standing.

The purpose of the present experiment was to investigate whether and how using a light fingertip touch for postural control during quiet standing requires additional attentional demands. Nine young healthy university students were asked to respond as rapidly as possible to an unpredictable auditory stimulus while maintaining stable seated and upright postures in three sensory conditions: vision, no-vision and no-vision/touch. Touch condition involved a gentle light touch with the right index finger on a nearby surface at waist height. Center of foot pressure (CoP) displacements were recorded using a force platform. Reaction times (RTs) values were used as an index of the attentional demand necessary for calibrating the postural system. Results showed decreased CoP displacements in both the vision and no-vision/touch conditions relative to the no-vision condition. More interestingly, a longer RT in the no-vision/touch than in the vision and no-vision conditions was observed. The present findings suggest that the ability to use a light fingertip touch as a source of sensory information to improve postural control during quiet standing is attention demanding.

Adult↗
PubMed2006

Multisensory reweighting of vision and touch is intact in healthy and fall-prone older adults.

Unexplained falls in older adults are thought to arise from subtle deficits in multiple components of the postural control system, including peripheral sensory loss and central sensory processing. One commonly proposed central sensory processing deficit is a decline in the adaptive use of changing or conflicting sensory inputs for estimating body dynamics, i.e., multisensory reweighting. We examined the assumption of impaired multisensory reweighting in healthy and fall-prone older adults using quantitative methods that have previously demonstrated reweighting in young adults. Standing subjects were exposed to simultaneous medio-lateral oscillatory visual and fingertip touch inputs at varying relative amplitudes. No group differences in overall levels of vision and touch gain were found. Both healthy and fall-prone older adults demonstrated the same pattern of adaptive gain change as healthy young adults. Like the young adults, both elderly groups displayed clear evidence of intra- and inter-sensory reweighting to both vision and touch motion stimuli. These data suggest that, for small amplitude vision and touch stimuli, the central sensory reweighting adaptation process remains intact in healthy and fall-prone older adults with sufficiently intact peripheral sensation.

Accidental Falls↗
PubMed2002

Ionic signaling in plant responses to gravity and touch.

Touch and gravity are two of the many stimuli that plants must integrate to generate an appropriate growth response. Due to the mechanical nature of both of these signals, shared signal transduction elements could well form the basis of the cross-talk between these two sensory systems. However, touch stimulation must elicit signaling events across the plasma membrane whereas gravity sensing is thought to represent transformation of an internal force, amyloplast sedimentation, to signal transduction events. In addition, factors such as turgor pressure and presence of the cell wall may also place unique constraints on these plant mechanosensory systems. Even so, the candidate signal transduction elements in both plant touch and gravity sensing, changes in Ca2+, pH and membrane potential, do mirror the known ionic basis of signaling in animal mechanosensory cells. Distinct spatial and temporal signatures of Ca2+ ions may encode information about the different mechanosignaling stimuli. Signals such as Ca2+ waves or action potentials may also rapidly transfer information perceived in one cell throughout a tissue or organ leading to the systemic reactions characteristic of plant touch and gravity responses. Longer-term growth responses are likely sustained via changes in gene expression and asymmetries in compounds such as inositol-1,4,5-triphosphate (IP3) and calmodulin. Thus, it seems likely that plant mechanoperception involves both spatial and temporal encoding of information at all levels, from the cell to the whole plant. Defining this patterning will be a critical step towards understanding how plants integrate information from multiple mechanical stimuli to an appropriate growth response.

Calcium↗
PubMed1988

The dorsal cell, one class of primary sensory neuron in the lamprey spinal cord. I. Touch, pressure but no nociception--a physiological study.

The dorsal cells in the lamprey spinal cord are primary sensory neurons. The cells were classified by Martin and Wickelgren in 1971 into 3 different groups, touch, pressure and nociceptive, according to their responses to mechanical stimulation of the skin. While confirming the presence of touch and pressure cells in the present study, we found no evidence for the existence of nociceptive spinal dorsal cells. Further we show that touch and pressure cells have different response latencies to a 40-ms hyperpolarizing current pulse. Measured from the end of the pulse to the initiation of the action potential, touch cells have a response latency shorter than 11 ms, whereas the pressure cells have a response latency longer than 11 ms.

Action Potentials↗
PubMed1995

Perceived touch deprivation and body image: some observations among eating disordered and non-clinical subjects.

The developmental literature suggests that touch, consisting of secure holding and hugging, plays an important role in the formation of body image. We tested the hypothesis that women with anorexia nervosa and/or bulimia nervosa (N = 59), conditions associated with body image problems, report a greater deprivation of tactile nurturance than a sample of non-clinical randomly selected women (N = 140) from the community. Measures of body image included the Drive for Thinness and Body Dissatisfaction subscales of the Eating Disorder Inventory. Perceived touch deprivation was rated on a 10-point scale, previously developed by the author. Analysis of covariance, controlling for the effects of age and body mass index, revealed that the eating disorder group reported greater (p < 0.0001) body image concerns and perceived greater (p < 0.0001) touch deprivation both during their childhood and their current life, than the non-clinical group. Our preliminary empirical findings suggest that touch deprivation may play a role in body image pathologies.

Adult↗
PubMed1986

Face touching in primates: a closer look.

Dimond and Harries (Neuropsychologia 22, 227-233, 1984) claim that monkeys, unlike great apes and humans, rarely touch their faces. These authors reported the existence of a left-hand preference for face touching in great apes and humans. Using two species of macaques, we found an incidence of face touching by monkeys which was much higher than that reported by Dimond and Harries. Moreover, a re-analysis of their data failed to show any evidence for species differences in lateralization of face touching by primates.

Animals↗
PubMed1984

Touch sensibility in the hand.

Touch sensibility must be evaluated in most of our patients, and must be re-evaluated in many of them following surgery. Touch sensibility must be tested in our disability evaluations and in order to prognosticate regarding hand function. Touch sensibility evaluation can provide a non-invasive guide to acute compartmental syndrome management. Touch sensibility must be re-educated following nerve repair.

Compartment Syndromes↗
PubMed1984

A fluorescent microscopic study of the development of rat touch domes and their Merkel cells.

The ability of the fluorescent dye quinacrine to label epidermal Merkel cells was used to study the development of touch domes (Haarscheiben) in rat skin. In embryonic and early postnatal pups, sites of touch dome primordia were reliably located within strips of separated trunk epidermis by the occurrence of discrete clusters of fluorescent cells scattered across the basal cell layer. As in excised adult domes, most of these fluorescent (Merkel) cells lay caudal to the emerging tylotrich hair follicle and the cell cluster formed an annular or crescentric disc. Though all the touch domes that comprise the adult population appear to contain labelled Merkel cells by postnatal day 4, the number of these cells per dome continues to increase some 3-4 fold after birth to reach the average adult number (ca 90 cells) on the dorsal trunk around the fifth week. At about this time the adult size (ca 250 micron) of the dorsal Haarscheiben is also reached, as estimated by the length of the long axis of the fluorescent disc. The rostro-caudal orientation of this long axis varied from dome to dome, usually in the range 0-45 degrees clockwise or counterclockwise, and a functional correlate of this is suggested. The density of labelled dome primordia is higher on the dorsal than on the ventral trunk from as early as embryonic day E20-21 and remains higher although the density of domes decreases steadily across the skin during postnatal growth of the animal. This study utilizes a novel fluorescent labelling technique that is applicable to microscopic studies on the development of Merkel cells within their epithelial locations, in this instance the rat touch domes. Although the full population of domes is established early in development, the Merkel cells within a dome continue to increase in number for several weeks after physiological function is known to appear in this structure.

Animals↗
PubMed1990

The use of touch with the hospitalized psychiatric patient.

A descriptive study was designed to identify and describe the ways in which registered nurses use nonprocedural touch in the inpatient psychiatric setting. Natural setting observation and nurse interviews were used to examine the decision-making process and intentions of nurses who used touch. Twenty-five incidents of nonprocedural touch initiated by 13 registered nurses with 17 psychiatric patients were recorded over 27.5 hours of observations. Touch was primarily used by nurses in a discriminating manner and for specific reasons, and was correlated with numerous factors such as the patient's age and gender, and the nurse's feelings, beliefs, intuition, and personal style.

Adolescent↗
PubMed1994

The effects of therapeutic touch and relaxation therapy in reducing anxiety.

This study examines the effects of two noninvasive procedures on experienced anxiety. Thirty-one inpatients of a Veterans Administration psychiatric facility were randomly assigned to one of two treatment conditions, (therapeutic touch and relaxation therapy) or to a therapeutic touch placebo condition. An additional 13 patients were excluded because of failure to meet criteria for the study or failure to complete the procedures. Each subject completed a self-report anxiety measure and was rated for amount of motor activity before and after each of two 15-minute treatment sessions in a 24-hour period. Subjects' belief in the effectiveness of the intervention was measured. Expectancy did not correlate with outcome and was not analyzed further. Multivariate analysis of variance (MANOVA) showed that whereas relaxation therapy provided significant reduction of anxiety on the self-report measure and the movement measure, the nursing intervention of therapeutic touch resulted in significant reductions of reported anxiety. The control group showed small but nonsignificant effects. Results suggests that both relaxation and therapeutic touch are effective palliatives to experienced anxiety. Implications for nursing theory are discussed.

Adult↗
PubMed2006

Peripheral neuropathy and object length perception by effortful (dynamic) touch: a case study.

The spatial extents of hand-held objects can be perceived nonvisually by wielding them. This ability of effortful or dynamic touch to exploit the mass moments of an object to perceive its length was evaluated with a 40-years old right-handed woman with surgically treated Arnold-Chiari Type 1 Malformation and cervical syrinx. At the time of the experiment she presented with loss of discriminative touch in the left arm but no comparable sensory deficits in the right arm or the lower extremities. She could neither identify objects in her left hand nor tell that they were in the hand while manipulating them. She could, however, grasp an object tightly and wield it on request. In the experiment she wielded weighted rods of 45, 60, and 80cm length about the wrist. There were two main results. First, her nonvisual perception of rod length by the insensate left arm scaled systematically with rod moment of inertia. The scaling matched that of the intact right arm and the nondominant arm of haptically unimpaired controls tested with rods of similar dimensions. Second, her right arm was superior in accuracy and reliability than her insensate left arm and was equal to or better than the dominant arm of the control group on key measures of nonvisual length perception. The first result was evaluated in respect to the notions of numb touch and differences in the neural bases of discriminative and effortful touch. The second result was discussed in terms of contralateral cortical enhancement by deafferentation.

Adult↗
PubMed2004

Extracellular proteins organize the mechanosensory channel complex in C. elegans touch receptor neurons.

Specialized extracellular matrix (ECM) is associated with virtually every mechanosensory system studied. C. elegans touch receptor neurons have specialized ECM and attach to the surrounding epidermis. The mec-1 gene encodes an ECM protein with multiple EGF and Kunitz domains. MEC-1 is needed for the accumulation of the collagen MEC-5 and other ECM components, attachment, and, separately, for touch sensitivity. MEC-1 and MEC-5 bind to touch processes uniformly and in puncta. These puncta colocalize with and localize the mechanosensory channel complex in the touch neurons. In turn, the production of the MEC-1 and MEC-5 puncta appears to rely on interactions with the neighboring epidermal tissue. These and other observations lead us to propose that extracellular, but not cytoskeletal, tethering of the degenerin channel is needed for mechanosensory transduction. Additionally, our experiments demonstrate an important role of the ECM in organizing the placement of the channel complex.

Alleles↗
PubMed1997

Touch sensibility in the breast after subcutaneous mastectomy and immediate reconstruction with a prosthesis.

Touch sensibility was assessed with von Frey's monofilaments in the breasts of 10 healthy women (controls) and of 80 women with breast cancer who at least 1 year previously had undergone subcutaneous mastectomy and immediate reconstruction with a prosthesis. Touch thresholds were measured at nine positions on each breast. Low threshold values (< 3.2 mN) and good reproducibility were found in the controls. In the patients' surgically treated breasts normal (< 3.2 mN) or subnormal (< 20 mN) median threshold values were found outside the areola. Higher median values were noted on the areola and nipple; on the nipple, however, one third of the patients had normal sensibility while 14% lacked sensibility. The only factors found to influence the results were simultaneous subcutaneous reduction mammaplasty (lower touch thresholds) and the localisation of the incision (slightly lower thresholds for lazy-S than inframammary incision). These results confirm the clinical impression that touch sensibility is substantially retained after subcutaneous mastectomy and immediate reconstruction with a prosthesis.

Aged↗
PubMed1998

Parental touch of the neonate: encourage or condemn?

The available literature regarding parental touch and its use on premature infants indicates differing views on whether touch should be encouraged or condemned. Findings of this literature review indicate that touch can have a detrimental physical effect on the infant, however positive long-term benefits for parent and child. The absence of direct guidelines for nursing staff working in a neonatal intensive care unit make decisions about parental touch difficult. The result from this literature review suggests that guidelines for nursing staff need to be established, so that optimum care is provided for both infant and parent.

Adult↗
PubMed2003

Master scaling of perceived intensity of touch, cold and warmth.

A new approach is presented for scaling perceived intensity of touch, cold and warmth based on magnitude estimation. In this method named master scaling thenar is utilized as common reference area for scaling and calibrating perceived intensity. The master scaling is particularly well suited for clinical applications in which the stimulation in pain-affected body areas creates a complex perception (e.g., paradoxical heat for cold stimulation) and/or aberrant psychophysical functions for perceived intensity. The results from three different experiments showed that: (a) All patients and healthy subjects were able to scale adequately the perceived intensity of touch, cold, and warmth at unaffected body areas. (b) Thenar stimulations were shown to be adequate common references in the joint scaling of perceived intensity of other body areas in pain patients as well as healthy persons. (c) Individual thenar psychophysical functions can be used for screening patients and healthy persons with regard to their ability to scale perceived intensity of touch, cold and warmth. (d) Master scaled perceived intensity scales can be used for determining if various pain-unaffected body areas are normal or abnormal in patients and in healthy persons. (e) The interindividual variation in perceived intensity is considerably reduced after master scaling and approaches that of intraindividual variation as found in olfaction and hearing. Finally, empirically based thenar Master Functions of perceived intensity for touch, cold and warmth are proposed to be used in future sensory testing of patients, as well as of healthy persons.

Adult↗
PubMed1996

A reflection of a Therapeutic Touch experience: case study I.

The purpose of this case study was to explore the experiences of giving and receiving Therapeutic Touch. Attempts were made to capture the subjective qualities of the experience by providing a description of the Therapeutic Touch interaction that took place. The central theme of this study is the process of reflection-in-action. This process is shown to facilitate learning; it is an effective vehicle for expanding and developing the knowledge and skills of Therapeutic Touch. This case study provides valuable qualitative information on a Therapeutic Touch experience. It has been possible to analyse this information in a more critical way through reflective thinking.

Female↗
PubMed1998

Reflection of a therapeutic touch experience: case study 2.

The purpose of this case study was to explore the experience of both giving and receiving Therapeutic Touch. A subjective account of the Therapeutic Touch experience is given in an attempt to throw light on its unique creative and therapeutic qualities. In most instances it was shown that the experience of both giving and receiving Therapeutic Touch was a parallel experience. This case study explores the effects of Therapeutic Touch on a client experiencing pain and associated anxiety. Whilst a response to treatment was observed, the need for further case studies and research studies in this area was identified.

Adult↗