Gentle Tactile Stimulation Research Articles

Differential effects of radiant and mechanically applied thermal stimuli on human C-tactile afferent firing patterns.

C-tactile (CT) afferents respond to gentle tactile stimulation, but only a handful of studies in humans and animals have investigated whether their firing is modified by temperature. We describe the effects of radiant thermal stimuli, and of stationary and very slowly moving mechanothermal stimuli, on CT afferent responses. We find that CT afferents are primarily mechanoreceptors, as they fired little during radiant thermal stimuli, but they exhibited different patterns of firing during combined mechano-cool stimulation compared with warming. CTs fired optimally to gentle, very slowly moving, or stationary mechanothermal stimuli delivered at neutral temperature (~32°C, normal skin temperature), but they responded with fewer spikes (median 67% decrease) and at significantly lower rates (47% decrease) during warm (~42°C) tactile stimuli. During cool tactile stimuli (~18°C), their mean instantaneous firing frequency significantly decreased by 35%, but they often fired a barrage of afterdischarge spikes at a low frequency (~5 Hz) that outlasted the mechanical stimulus. These effects were observed under a variety of stimulus conditions, including during stationary and slowly moving touch (0.1 cm/s), and we complemented these tactile approaches using a combined electrical-thermal stimulation experiment where we found a suppression of spiking during warming. Overall, CT afferents are exquisitely sensitive to tactile events, and we show that their firing is modulated with touch temperatures above and below neutral skin temperature. Warm touch consistently decreased their propensity to fire, whereas cool touch produced lower firing rates but afterdischarge spiking. NEW & NOTEWORTHY C-tactile (CT) afferents are thought to underpin pleasant touch, and previous work has shown that they respond optimally to a slow caress delivered at typical (neutral) skin temperature. Here, we show that, although CTs are primarily mechanoreceptive afferents, they are modified by temperature: warm touch decreases their firing, whereas cool touch produces lower firing rates but long-lasting spiking, frequently seen as afterdischarges. This has implications for the encoding of affective sensory events in human skin.

The Relationship between Gentle Tactile Stimulation on the Fetus and Its Temperament 3 Months after Birth.

Objective. The aim of this study was to evaluate the effect of gentle tactile stimulation on the fetus in its temperament 3 months after birth. Method. A total of 302 mother-3-month-infant dyads enrolled the retrospective cohort study. 76 mothers had regular gentle tactile stimulation on the fetus in their pregnancy; 62 mothers had irregular tactile stimulation on the fetus, and the rest of 164 mothers who had no tactile stimulation served as nonexposure group. Temperament was assessed using the EITS (a nine-dimensional scale of temperament). Results. Significant difference in temperament type was found among infants in 3 groups at 3 months of age. In the regular practice group, the babies with easy type temperament accounted for 73.7%, which was higher than that in irregular practice group (53.2%, P = 0.012) and that in the control group (42.1%, P < 0.001). Compared to infants in no practice group, the infants who had received regular gentle tactile stimulation before birth were lower in negative mood (P = 0.047) while higher in adaptability (P < 0.001), approach (P = 0.001), and persistence (P = 0.001), respectively. Conclusion. Regular gentle tactile stimulation on fetus may promote the formation of easy type infant temperament.

Part 11: Neonatal Resuscitation

Part 11: Neonatal Resuscitation

Practical aspects of resuscitating asphyxiated newborn infants.

Of all newborn infants, 5% require some degree of basic life support at birth. Newborn resuscitation therefore is one of the most frequent procedures carried out in medicine. It is therefore important that the routines in use are evidence based. Newborn resuscitation can be divided into ten steps: (1) initial stabilisation; (2) evaluation; (3) ventilation; (4) oxygen supplementation; (5) external heart massage; (6) medication; (7) response assessment; (8) withdrawal; (9) post resuscitation care; and (10) documentation. The procedures used in these steps are rarely based on scientific investigation and there is a need for more research in this field. Training programmes, identification of risk cases and preparation for resuscitation should be part of the routine in all delivery units. It is underlined that the need for oxygen, external heart massage or medication is rare. Most depressed newborn infants manage well with suctioning, gentle tactile stimulation or a few ventilations with a bag and mask.

Influence of tactile stimulation of the rat gastric mucosa on blood flow and acid output

The influence of tactile stimulation of the gastric mucosa (mimics the mechanical influence of the food bolus) on the gastric mucosal blood flow and acid output was studied in rats anesthetized with Inactin. Blood flow was measured with laser-Doppler flowmetry (LDF) with the probe positioned above the gastric mucosa, and acid secretion was measured at regular intervals by titration of the saline covering 0.8 cm2 of the mucosa. After gentle tactile stimulation (wiping with cotton tips) of the mucosa for 20 s, blood flow increased to approximately 250% of the control value and then returned to the control level 15 min later, whereas acid output was transiently reduced immediately after tactile stimulation. Pretreatment with lidocaine, methysergide, or hexamethonium did not change the results of tactile stimulation on the blood flow. After indomethacin (3 mg/kg i.v.) LDF was significantly reduced by 33% and the hyperemic response to tactile stimulation was almost abolished. This suggests that endogenously released prostaglandins, not evoked through activation of intramural reflexes that can be blocked by lidocaine, methysergide or hexamethonium, are responsible for the hyperemia seen after tactile stimulation of the gastric mucosa.

Changes in the pharmacodynamic response to fentanyl in neonates during continuous infusion

Tolerance to opioid-induced sedation has been reported in neonates sedated with fentanyl by continuous infusion while undergoing extracorporeal membrane oxygenation. We undertook a prospective analysis of eight newborn infants sedated with fentanyl during extracorporeal membrane oxygenation therapy for respiratory failure. We recorded daily mean fentanyl infusion rate, measured serial plasma fentanyl concentrations, and documented the occurrence of spontaneous motor activity or respiratory effort. Mean fentanyl infusion rate increased steadily during the period of infusion from a mean of 9.2 +/- 1.9 (SEM) micrograms/kg per hour on day 1 to a mean of 21.9 +/- 4.5 micrograms/kg per hour by day 6. Mean plasma fentanyl concentrations increased steadily during the period of fentanyl infusion from 3.1 +/- 1.1 (SEM) ng/ml on day 1 to 13.9 +/- 3.2 ng/ml on day 6. All infants exhibited movement in response to gentle tactile stimulation throughout the period of infusion, and seven of eight infants manifested spontaneous movement of the extremities and eye opening. Our results indicate that when fentanyl is used for sedation in neonates, the plasma concentrations required for satisfactory sedation steadily escalate, possibly indicating the rapid development of tolerance to the sedating effects of fentanyl.

Activity patterns of motoneurons in the spinal dogfish in relation to changing Active locomotion

Rhythmic motoneuronal activity was recorded from segmental motor nerves of moving (spinal swimming) and paralysed (fictive swimming) spinal dogfish ( Scyliorhinus canicula ), and, in the paralysed preparation, microelectrode recordings were made from spinal cord motoneurons. The motoneurons could be divided into two groups, according to their activity patterns. Group I ( n = 31) were inactive during Active swimming and did not respond to gentle tactile stimulation; when recorded from intracellularly they showed stable to weakly oscillating (&lt; 1 mV) membrane potentials. Group II ( n = 15) fired bursts of action potentials in phase with the motor nerve activity, which were superimposed upon larger (up to 17 mV) depolarizations, and responded to gentle tactile stimulation. Two of these cells discharged also in the interburst interval of the nerve activity. Decreases in cycle period of the Active swimming (i.e. increases in locomotor frequency) were instantaneously accompanied by increases in the amplitude of the rectified and integrated motor nerve signal, which represents peak activity of group II motoneurons, and decreases in the duration of the motor burst. Similar instantaneous changes were seen in the firing frequency and burst duration of individual group II motoneurons. The conformity between unit and population behaviour with changing speed of Active swimming, and the close correspondence observed between the form of the excitatory postsynaptic potentials recorded from individual motoneurons and the form of the integrated neurogram, suggest that the group II motoneurons receive a common excitatory drive. Re- and decruitment of motoneurons were virtually absent during these changes of speed. During unstimulated spinal swimming, regular left—right alternating EMG activity is recorded from the red but not from the white part of the myotome. The ratio of group I to group II motoneurons (31:15) recorded in this study agrees with the previously reported proportion of axons in the spinal motor nerve that project to the white and red muscle fibres, respectively. We suggest, therefore, that group II motoneurons innervate the red and superficial muscle fibres and group I the white fibres. The different activity patterns of the two motoneuronal groups in the spinal fish probably reflect the different ways the red and white muscle systems are used during locomotion

How does an eclosing fly deal with obstacles?

ABSTRACT. Stereotyped eclosion behaviour of Sarcophaga bullata Parker (Diptera, Sarcophagidae) consists of two different repetitive sequences of movements. One, which is instrumental for making forward progress in extricating the body from the puparium or for digging through the soil, is called the programme for forward movement (PFM). The other, which is performed as a response to an obstruction, is called the programme for obstruction removal (POR). The initial and final phases of each repetitive sequence are identical in both programmes, the sequences differing only in the middle portion. In the POR, the locomotor elements of the PFM sequence (peristalsis) are substituted by a train of repetitive expansions of the ptilinum, which are caused by simultaneous contractions of the abdominal and thoracic muscles. These ptilinal movements function as an air hammer against the obstruction. Switching from the PFM to POR can be experimentally induced by a rough mechanical stimulation of the head (squeezing, pushing against a barrier) but not by gentle tactile stimulation of the ptilinum or antennae. The critical period for induction of the POR is in the phase of the PFM sequence at which the two programmes diverge. A constant mechanical stimulus is necessary for a sustained performance of the whole POR. A hypothetical scheme of the neural basis of this behaviour is suggested.

Three forms of the scratch reflex in the spinal turtle: movement analyses.

The scratch reflex is a motor task exhibited by the hindlimb of a turtle after complete transection of the spinal cord just posterior to the forelimb enlargement. The scratch is elicited by applying gentle tactile stimulation to a site innervated by spinal segments caudal to the level of the transection. During the scratch response, the ipsilateral hindlimb reaches toward and rubs against the stimulated site. Each scratch response consists of either a single rub or a rhythmic series of rubs. There are three types or "forms" of the scratch reflex in the spinal turtle: rostral scratch (previously termed the scratch reflex in Refs. 5, 43, 45), pocket scratch, and caudal scratch. We have characterized each scratch form according to which portion of the hindlimb is used to rub against the stimulated site. During a rostral scratch, the dorsum of the foot and/or toes is used to rub against the stimulated site. During a pocket scratch, the side of the thigh, knee, and/or calf is used to rub. During a caudal scratch, the heel or side of the foot is used to rub. Each scratch form has a distinct receptive field on the turtle shell and skin. A rhythmic scratch response to maintained tactile stimulation consists of as many as 10-25 cycles. We have divided each cycle of movement into a prerub, rub, and postrub phase. Extension of the knee joint occurs during the rub phase of each scratch cycle for all scratch forms. The timing of the extension phase of the knee joint movement within the protraction-retraction (flexion-extension) cycle of the hip joint is different for each form of the scratch. During a rostral scratch, extension of the knee joint occurs when the hip is protracted. During a pocket scratch, knee extension occurs when the hip is retracting. During a caudal scratch, knee extension occurs when the hip is retracted. The spinal turtle therefore shifts the timing of movements of a distal joint (knee) with respect to the timing of movements of a proximal joint (hip) to obtain appropriate scratching movements to different regions of the body. A narrow transition zone exists between the receptive field for one form of the scratch and the nearby receptive field for another form of the scratch. There is a rostral-pocket transition zone and caudal-pocket transition zone in the spinal turtle.(ABSTRACT TRUNCATED AT 400 WORDS)

Control of intrinsic reticulo-ruminal motility in the vagotomized sheep.

The intrinsic motility of the reticulo-rumen was studied by electromyography in nineteen sheep subjected to bilateral thoracic vagotomy and maintained by intragastric infusion of a complete liquid diet. The influences of distension, temperature and tactile and chemical stimuli on the intrinsic reticulo-ruminal motility were investigated. The level of electrical discharge in the reticulum and rumen in the first 3 days after vagotomy was increased progressively with distension without giving rise to the large group discharges characteristic of the long-term vagotomized sheep, and was reduced by atropine (0.1-1 mg kg-1) but not by hexamethonium (2 mg kg-1). In the long-term vagotomized animals, the frequency of the large group discharges over the reticulo-rumen varied with the degree of reticulo-ruminal distension. The discharges were absent below a threshold rumen volume; above the threshold they increased progressively with volume until a maximal rate of six to seven regular discharges per minute was established at large ruminal volumes. The discharges were abolished by atropine (0.1-1 mg kg-1) or hexamethonium (2 mg kg-1). With the rumen volume below the threshold, in all areas of the reticulo-rumen localized distension stimulated local discharge only and did not induce large group discharge. Replacement of rumen contents with an equal volume of 0.2 M-acetic, -propionic or -butyric acid buffered to pH 4.0 rapidly abolished the large group discharges over the entire reticulo-rumen. Replacement of rumen contents by an equal volume of 0.9% NaCl at 30 degrees C immediately abolished the large group discharges; at temperatures between 35 and 43 degrees C this had no effect. Gentle tactile stimulation increased local discharge in the reticulum and cranial dorsal sac but not in other areas of the rumen and did not affect large group discharge in any region. It is concluded that the intrinsic reticulo-ruminal motility of chronically vagotomized sheep is principally regulated by the degree of reticulo-ruminal distension. Like the C.N.S.-controlled motility of the vagus-intact sheep it is inhibited by high concentrations of volatile fatty acids. Local control mechanisms therefore may interact with central control in the over-all regulation of motility in vagus-intact sheep.

Development of nasal respiration and sniffing in the rat

Nasal inhalation cycles of 1- to 20-day-old rat pups were measured and recorded using strain gage plethysmography, a technique that compares favorably with more common cinemagraphic methods of quantification. Respiratory recordings were taken from individual pups before and after habituation to a novel but bland environment, and in response to repeated, counterbalanced presentations of the odor of amyl acetate and gentle tactile stimulation. Baseline respiratory rates increased during the first two postnatal weeks and subsided in the third week. Rat pups of all ages displayed significant respiratory acceleration (polypnea) to suprathreshold olfactory and tactile stimulation, although there were ontogenetic differences in response topography. The occurrence and duration of bursts of polypnea increased with age. Sniffing, rhythmically regular episodes of polypnea, appeared as early as Day 3, but did not become prominent until about Day 11. The relationship between the development of nasal respiration and sniffing, and the development of olfaction in the rat was discussed.

Antinociceptive effects of vaginal stimulation in rats: Neurophysiological and behavioral studies

The present studies extend previous findings that probing the vaginal cervix of rats blocks withdrawal reflexes and induces immobilization 44. In the present studies, we report that this effect is apparently not due to an action on the final motor pathway, for limb or facial movement induced by electrical stimulation of the pyramidal tract was not suppressed by the probing. In contrast, the sensory response of neurons in the ventrobasal complex of the thalamus to noxious pinch stimulation was markedly attenuated by probing the vaginal cervix. However, the response of these neurons to gentle tactile stimulation was not attenuated, indicating a selective antincociceptive effect of the probing. The antinociceptive effect was not necessarily related to changes in arousal. These findings were supported by behavioral studies in which probing the vaginal cervix blocked vocalization in response to tail shock, and elevated the current threshold for eliciting vocalization in response to tail shock. Furthermore, during the probing, the rats were found to be capable of vocalizing in response to presumably non-noxious (lifting) stimulation, even though their vocalization response to noxious tail shock was suppressed. These studies suggest that probing the vaginal cervix in rats exerts an analgesic action.

Cells of origin of the spinocervical tract in the monkey

The responses of cells of the spinocervical tract were recorded from the lumbosacral spinal cord in anesthetized monkeys. The neurons were identified by antidromic activation following stimulation of the dorsal part of the lateral funiculus at C 3. Recordings were also made in a few experiments from neurons of the lateral cervical nucleus. These cells were identified by by antidromic activation following stimulation of the contralateral medial lemniscus and by demonstration of their receptive fields on the skin of the trunk or hind limb. Most of the cells of origin of the spinocervical tract were in the region of the dorsal horn comparable to laminae IV and V in the cat. However, some were more ventral and one was in lamina I. The conduction velocities of the axons ranged from 7.1 to 60 m/sec (mean of 27.8 m/sec). The receptive fields of the spinocervical tract neurons were on the ipsilateral hind limb. Many of the cells were activated by hair movement or by gentle tactile stimulation of the skin. Others were excited not only by comparable stimuli but, in addition, by more intense mechanical stimulation of the skin. One cell required a noxious stimulus for its activation. A strong thermal stimulus caused an increased discharge of some of the cells. There was a somatotopic organization of the cells within the dorsal horn. Laterally situated neurons were associated with peripheral receptive fields on the dorsal surface of the limb, while medially located neurons had receptive fields on the ventral surface of the limb. The rostrocaudal somatotopic organization was dermatomal. The neurons of the lateral cervical nucleus were activated by hair movement or by tactile stimulation. It is concluded that the monkey somatosensory system includes a spinocervicothalamic pathway which is comparable to that found in the carnivore.