Role of tactile stimulation during the preweaning period on the development of the peripheral sensory sural (SU) nerve in adult artificially reared female rat.

Maternal deprivation, as a result of the artificial rearing (AR) paradigm, disturbs electrophysiological and histological characteristics of the peripheral sensory sural (SU) nerve of infant and adult male rats. Such changes are prevented by providing tactile or social stimulation during isolation. AR also affects the female rat's brain and behavior; however, it is unknown whether this early adverse experience also alters their SU nerve development or if tactile stimulation might prevent these possible developmental effects. To assess these possibilities, the electrophysiological and histological characteristics of the SU nerve from adult diestrus AR female rats that: (i) received no tactile stimulation (AR group), (ii) received tactile stimulation in the anogenital and body area (AR-Tactile group), or (iii) were mother reared (MR group) were determined. We found that the amplitude, but not the area, of the evoked compound action potential response in SU nerves of AR rats was lower than those of SU nerves of MR female rats. Tactile stimulation prevented these effects. Additionally, we found a reduction in the outer diameter and myelin thickness of axons, as well as a large proportion of axons with low myelin thickness in nerves of AR rats compared to the nerves of the MR and AR-Tactile groups of rats; however, tactile stimulation only partially prevented these effects. Our data indicate that maternal deprivation disturbs the development of sensory SU nerves in female rats, whereas tactile stimulation partially prevents the changes generated by AR. Considering that our previous studies have shown more severe effects of AR on male SU nerve development, we suggest that sex-associated factors may be involved in these processes.

Supplemental vibrissal extensions as an alternative to improve the tactile sensitivity of blind dogs - a preliminary approach investigation.

OBJECTIVE: This preliminary study suggests a way to artificially extend vibrissae of blind dogs to assist ambulation and avoiding facial contact with obstacles. PROCEDURES: Fourteen irreversibly blind dogs had 5-6 mystacial vibrissae on each side of the face supplementally extended by attaching carefully chosen adult pig hairs to them and were subjected to a maze test before and after the procedure. In three of these dogs the test was repeated one more time after all the extensions had fallen off. Collision counts and course times with and without extensions were analyzed and compared. A p-value > 0.05 was considered significant. RESULTS: Median number of collisions was significantly higher post-extensions (5 IQR 2.25) and after extensions had fallen off (4 IQR 7.50) compared to pre-extensions (1 IQR 1), p = 0.021. Median times were significantly higher pre-extension (25.6 IQR 8.98) and after the extensions had fallen off, compared to the post-extension performance (22.8 IQR 8.55), p = 0.04. CONCLUSION: Vibrissae play an important role in the tactile perception of blind dogs, and our preliminary results suggest that extending this sensory organ possibly improves obstacle location and their quality of life.

Modulation of facial muscle responses by another person's presence and affiliative touch during affective image viewing.

Stimulating CT-afferents by forearm caresses produces the subjective experience of pleasantness in the receiver and modulates subjective evaluations of viewed affective images. Receiving touch from another person includes the social element of another person's presence, which has been found to influence affective image evaluations without involving touch. The current study investigated whether these modulations translate to facial muscle responses associated with positive and negative affect across touch-involving and mere presence conditions. Female participants (N = 40, M(age) = 22.4, SD = 5.3) watched affective images (neutral, positive, negative) while facial electromyography was recorded (sites: zygomaticus, corrugator). Results from ANOVAs showed that providing touch to another person or oneself modulated zygomaticus site responses when viewing positive images. Providing CT-afferent stimulating touch (i.e., forearm caresses) to another person or oneself dampened the positive affective facial muscle response to positive affective images. Providing touch to another person generally increased corrugator facial muscle activity related to negative affect. Receiving touch did not modulate affective facial muscle responses during the viewing of affective images but may have effects on later cognitive processes. Together, previously reported social and touch modulations of subjective evaluations of affective images do not translate to facial muscle responses during affective image viewing, which were differentially modulated.

Caresses, whispers and affective faces: A theoretical framework for a multimodal interoceptive mechanism underlying ASMR and affective touch: An evolutionary and developmental perspective for understanding ASMR and affective touch as complementary processes within affiliative interactions.

Autonomous sensory meridian response (ASMR) and affective touch (AT) are two phenomena that have been independently investigated from separate lines of research. In this article, I provide a unified theoretical framework for understanding and studying them as complementary processes. I highlight their shared biological basis and positive effects on emotional and psychophysiological regulation. Drawing from evolutionary and developmental theories, I propose that ASMR results from the development of biological mechanisms associated with early affiliative behaviour and self-regulation, similar to AT. I also propose a multimodal interoceptive mechanism underlying both phenomena, suggesting that different sensory systems could specifically respond to affective stimulation (caresses, whispers and affective faces), where the integration of those inputs occurs in the brain's interoceptive hubs, allowing physiological regulation. The implications of this proposal are discussed with a view to future research that jointly examines ASMR and AT, and their potential impact on improving emotional well-being and mental health.

The pleasantness and unpleasantness of an object distinctively drives its grasping prediction: behavioral evidence.

Action and perception share a common sensorimotor network permitting a functional action-perception coupling. This coupling would permit to predict the outcome of others' actions. Moreover, recent findings suggest that action-perception linkage could be sensitive to emotional content of the visual scene. The present study sought to address how emotion inherent to an object (pleasantness and unpleasantness) affects action prediction processing. To this end, we compared the participants' temporal estimative of the hand contact with emotional objects in occlusion and full vision conditions. We found that the emotion strongly interfered in the prediction of its grasping. Indeed, the participants highly anticipated the touch instant for unpleasant valence compared to pleasant and neutral ones. Moreover, the visual conditions (i.e., occlusion and full vision) affect the magnitude of the predictive error except to unpleasant object. Accordingly, the present results unveil that pleasantness and unpleasantness of an object distinctively drive the prediction of its touch instant.

More than a feeling: Scalp EEG and eye signals in conscious tactile perception.

Understanding the neural basis of consciousness is a fundamental goal of neuroscience, and sensory perception is often used as a proxy for consciousness in empirical studies. However, most studies rely on reported perception of visual stimuli. Here we present behavior, high density scalp EEG and eye metric recordings collected simultaneously during a novel tactile threshold perception task. We found significant N80, N140 and P300 event related potentials in perceived trials and in perceived versus not perceived trials. Significance was limited to a P100 and P300 in not perceived trials. We also found an increase in pupil diameter and blink rate and a decrease in microsaccade rate following perceived relative to not perceived tactile stimuli. These findings support the use of eye metrics as a measure of physiological arousal associated with conscious perception. Eye metrics may also represent a novel path toward the creation of tactile no-report tasks in the future.

Influence of E/I balance and pruning in peri-personal space differences in schizophrenia: A computational approach.

The encoding of the space close to the body, named peri-personal space (PPS), is thought to play a crucial role in the unusual experiences of the self observed in schizophrenia (SCZ). However, it is unclear why SCZ patients and high schizotypal (H-SPQ) individuals present a narrower PPS and why the boundaries of the PPS are more sharply defined in patients. We hypothesise that the unusual PPS representation observed in SCZ is caused by an imbalance of excitation and inhibition (E/I) in recurrent synapses of unisensory neurons or an impairment of bottom-up and top-down connectivity between unisensory and multisensory neurons. These hypotheses were tested computationally by manipulating the effects of E/I imbalance, feedback weights and synaptic density in the network. Using simulations we explored the effects of such impairments in the PPS representation generated by the network and fitted the model to behavioural data. We found that increased excitation of sensory neurons could account for the smaller PPS observed in SCZ and H-SPQ, whereas a decrease of synaptic density caused the sharp definition of the PPS observed in SCZ. We propose a novel conceptual model of PPS representation in the SCZ spectrum that can account for alterations in self-world demarcation, failures in tactile discrimination and symptoms observed in patients.

Maternal sensitivity and infant neural response to touch: an fNIRS study.

The mother's attunement to her infant's emotional needs influences her use of touching behaviors during mother-infant interactions. Moreover, maternal touch appears to modulate infants' physiological responses to affective touch. However, little is known about the impact of maternal sensitivity on infants' touch processing at a brain level. This study explored the association between maternal sensitivity when infants (N = 24) were 7 months old and their patterns of cortical activation to touch at 12 months. Brain activation was measured using functional near-infrared spectroscopy. Changes in oxy-hemoglobin (HbO2) and deoxy-hemoglobin (HHb) concentrations were measured in the left somatosensory cortex and right temporal cortex while infants received two types of tactile stimulation-affective and discriminative touch. Results showed that a lower maternal sensitivity was associated with a higher HbO2 response for discriminative touch over the temporal region. Additionally, infants of less sensitive mothers tended to present a higher response in HbO2 for affective touch over the somatosensory region. These findings suggest that less sensitive interactions might result in a lower exposure to maternal touch, which can be further related to infants' neural processing of touch.

Joint and individual effectiveness of galvanic cutaneous stimulation and tactile stimulation at decreasing Simulator Adaptation Syndrome.

This research was focused on investigating the effectiveness of galvanic cutaneous stimulation and tactile stimulation jointly and individually at mitigating Simulator Adaptation Syndrome. Forty drivers (mean age = 23.1 ± 3.4 years old, twenty women) participated in a driving simulation experiment. Total scores of the Simulator Sickness Questionnaire, head movements (an index of body balance), and driving performance variables were compared across four different stimulation conditions: i) baseline (where no stimulation was presented), ii) galvanic cutaneous stimulation and iii) tactile stimulation deployed individually, and iv) both techniques deployed jointly. The results showed that both techniques presented in conjunction alleviate Simulator Adaptation Syndrome and improve driving performance more effectively than when they are presented in isolation. Importantly, reduced head movements were only revealed when galvanic cutaneous stimulation was applied. We concluded that the reduction of this syndrome is due to an improvement of body balance (elicited by galvanic cutaneous stimulation), and a distraction from the symptoms (elicited by tactile stimulation). We encourage the use of both techniques simultaneously to decrease Simulator Adaptation Syndrome.

Recomendación para disminuir el riesgo de colapso súbito e inesperado posnatal / Guidance to reduce the risk of Sudden and Unexpected Postnatal Collapse

El contacto piel a piel al nacer (COPAP) entre madres y recién nacidos a término sanos es fundamental en los estándares de la Iniciativa Hospital Amigo de la Madre y el Niño de Unicef. El COPAP inmediatamente después del nacimiento favorece la estabilidad cardiorrespiratoria, la prevalencia y duración de la lactancia materna y el vínculo madre-hijo, y disminuye el estrés materno. Existe preocupación por los casos de colapso súbito inesperado posnatal durante el COPAP con el bebé en decúbito prono sobre el torso desnudo materno. Si bien es infrecuente, evoluciona en el 50 % de los casos como evento grave de aparente amenaza a la vida y la otra mitad fallece (muerte súbita e inesperada neonatal temprana). Durante el COPAP y, al menos, las primeras 2 horas después del parto, el personal de Sala de Partos y recuperación debe observar y evaluar cualquier parámetro que implique una descompensación del bebé.

Early skin-to-skin contact (SSC) between mothers and healthy term newborns is a key part of the Unicef Baby Friendly Initiative Standards. SSC immediately after birth provides cardio-respiratory stability, improves prevalence and duration of breastfeeding, improves maternal-infant bonding and decreases maternal stress. There is a concern about cases of sudden unexpected postnatal collapse during a period of SSC with the infant prone on the mother ́s chest. Said collapse includes both severe apparent life-threatening event and sudden unexpected early neonatal death in the first week of life. Even if considered rare, consequences are serious with death in half of the cases and remaining disability in majority of the cases reported. For these reasons during SSC and for at least the first 2 hours after delivery, health care personnel in the delivery and recovery room should observe and assess for any sign of decompensation in the infant

Tactile stimulation of adult rats modulates hormonal responses, depression-like behaviors, and memory impairment induced by chronic mild stress: Role of angiotensin II.

Physical touch can help to decrease the effects of stress. The aim of this study was to evaluate the influence of tactile stimulation on the hormonal and behavioral responses of young adult rats submitted to chronic mild unpredictable stress (CMS), considering the role of angiotensin II (Ang II). In Experiment 1, male rats were divided into 4 groups: control, stress, tactile stimulation (TS), and stress + TS. CMS was applied for three weeks. Tactile stimulation was applied for seven weeks, five days a week. After the CMS protocol, depression-like behaviors were evaluated by forced swimming and sucrose consumption tests. Learning and memory were evaluated using the Y-maze test. Fifteen days after the CMS procedure, the animals were euthanized and the levels of stress hormones were determined. The hypothalamus was isolated for determination of the Ang II concentration. In Experiment 2, control and stressed rats, with or without treatment using losartan (angiotensin II type 1 receptor blocker), were evaluated using the same behavioral tests and the hypothalamus Ang II concentration was also determined. CMS increased plasma corticosterone, norepinephrine, and epinephrine concentrations, induced depression-like behaviors, impaired learning and memory, and increased the Ang II concentration in the hypothalamus. Tactile stimulation attenuated these stress-induced effects. Losartan treatment effectively prevented increase of the hypothalamic Ang II concentration and the development of depression-like behavior, and also reduced the impairment of learning and memory in the stressed animals. The results indicated that tactile stimulation seemed to protect adult rats against hormonal and behavioral chronic stress effects, and that Ang II could be involved in the CMS effects.

Neurophysiological correlates of force control improvement induced by sinusoidal vibrotactile stimulation.

OBJECTIVE: An optimal level of vibrotactile stimulation has been shown to improve sensorimotor control in healthy and diseased individuals. However, the underlying neurophysiological mechanisms behind the enhanced motor performance caused by vibrotactile stimulation are yet to be fully understood. Therefore, here we aim to evaluate the effect of a cutaneous vibration on the firing behavior of motor units in a condition of improved force steadiness. APPROACH: Participants performed a visuomotor task, which consisted of low-intensity isometric contractions of the first dorsal interosseous (FDI) muscle, while sinusoidal (175 Hz) vibrotactile stimuli with different intensities were applied to the index finger. High-density surface electromyogram was recorded from the FDI muscle, and a decomposition algorithm was used to extract the motor unit spike trains. Additionally, computer simulations were performed using a multiscale neuromuscular model to provide a potential explanation for the experimental findings. MAIN RESULTS: Experimental outcomes showed that an optimal level of vibration significantly improved force steadiness (estimated as the coefficient of variation of force). The decreased force variability was accompanied by a reduction in the variability of the smoothed cumulative spike train (as an estimation of the neural drive to the muscle), and the proportion of common inputs to the FDI motor nucleus. However, the interspike interval variability did not change significantly with the vibration. A mathematical approach, together with computer simulation results suggested that vibrotactile stimulation would reduce the variance of the common synaptic input to the motor neuron pool, thereby decreasing the low frequency fluctuations of the neural drive to the muscle and force steadiness. SIGNIFICANCE: Our results demonstrate that the decreased variability in common input accounts for the enhancement in force control induced by vibrotactile stimulation.

Neonatal tactile stimulation reverses alterations in fine structure of small, but not large myelinated fibers, from the optic nerve of iron-deficient rats: A size-based selectivity.

Iron is the most common micronutrient deficiency in the world and it is most prevalent in young children, exposing their developing brain to inadequate iron levels. The damage related to neuroanatomical parameters is not reversed after iron treatment. However, evidence suggest that tactile stimulation (TS) may offer great therapeutic efficacy in cases of nutritional disorders postnatally, since the brain is remarkably responsive to its interaction with the environment. Recently, we shown that neonatal iron deficient rats achieved some remedial effect by exposing them to TS treatment early in life, reinforcing the fact that the TS approach is a positive enriching experience, therefore, here we ask whether exposure to TS treatment, could also be employed to prevent fine structural changes in the fibers from optic nerve of rats maintained on an iron-deficient diet during brain development. To elucidate the protective effect of tactile stimulation, our methods resulted in 10,859 analyzed fibers, divided into small and large fibers. We found that iron deficiency led to a decreased axon, fiber and myelin size of small fibers, however, TS completely reversed the iron-decifiency-induced alteration on those fiber measurements. Large fibers were disproportionately affected by iron deficiency and there was no remediating effect due to tactile stimulation treatment. The present study adds new information regarding different alterations between small and large fibers due to diet and TS, which suggest a size-based selectivity. These results emphasize the concept that compromised brain development can be mitigated at an early age by environmental factors, such as tactile stimulation.

Proposal of the Tactile Glove Device.

This project aims to develop a tactile glove device and a virtual environment inserted in the context of tactile internet. The tactile glove allows a human operator to interact remotely with objects from a 3D environment through tactile feedback or tactile sensation. In other words, the human operator is able to feel the contour and texture from virtual objects. Applications such as remote diagnostics, games, remote analysis of materials, and others in which objects could be virtualized can be significantly improved using this kind of device. These gloves have been an essential device in all research on the internet next generation called "Tactile Internet", in which this project is inserted. Unlike the works presented in the literature, the novelty of this work is related to architecture, and tactile devices developed. They are within the 10 ms round trip latency limits required in a tactile internet environment. Details of hardware and software designs of a tactile glove, as well as the virtual environment, are described. Results and comparative analysis about round trip latency time in the tactile internet environment is developed.

The impact of maternal touch of the abdomen on cardiotocography fetal patterns.

INTRODUCTION: Some studies suggest that maternal touch of the abdomen produces an increase in the number of movements of the fetus. However, the influence of maternal touch of the abdomen on fetal cardiotocography patterns has not been studied. METHODS: This nonrandomized, before-after clinical trial that assessed fetal cardiotocography patterns during maternal touch of the abdomen in 28 low-risk pregnant women. RESULTS: Baseline fetal heart rate, accelerations, decelerations, and variability did not change with maternal touch of the abdomen, but fetal movements increased (p = 0.044). CONCLUSION: Fetal movements increases during maternal touch of the abdomen.

Lower limb amputees undergo long-distance plasticity in sensorimotor functional connectivity.

Amputation in adults is associated with an extensive remapping of cortical topography in primary and secondary sensorimotor areas. Here, we used tactile residual limb stimulation and 3T functional magnetic resonance imaging in humans to investigate functional connectivity changes in the sensorimotor network of patients with long-term lower limb traumatic amputations with phantom sensation, but without pain. We found a pronounced reduction of inter-hemispheric functional connectivity between homologous sensorimotor cortical regions in amputees, including the primary (S1) and secondary (S2) somatosensory areas, and primary (M1) and secondary (M2) motor areas. We additionally observed an intra-hemispheric increased functional connectivity between primary and secondary somatosensory regions, and between the primary and premotor areas, contralateral to amputation. These functional connectivity changes in specialized small-scale sensory-motor networks improve our understanding of the functional impact of lower limb amputation in the brain. Our findings in a selective group of patients with phantom limb sensations, but without pain suggest that disinhibition of neural inputs following traumatic limb amputation disrupts sensorimotor topology, unbalancing functional brain network organization. These findings step up the description of brain plasticity related with phantom sensations by showing that pain is not critical for sensorimotor network changes after peripheral injury.

Effect of force magnitude of touch on the components of postural sway.

BACKGROUND: Lightly touching the tip of the index finger on an external surface reduces the postural sway during upright standing due to the additional somatosensory information provided by the touch to the postural control system. But when the individuals apply more force, it provides more mechanical support. However, because most of the studies investigated only two levels of force, whether the control mechanisms of postural sway are affected by the different force levels was unknown. RESEARCH QUESTION: To examine the influence of the magnitude of force (up to 1, 2, 4, 6 or 8 N) applied to the touch bar on the mechanisms used to control the postural sway during quiet standing with eyes open or closed. METHODS: Ten young right-handed adults stood for 35 s on a force platform, with feet apart, while touched a rigid bar with different force levels with eyes open or closed. The amplitude and velocity of the center of pressure and its components, Rambling and Trembling trajectories, respectively, related to more supraspinal and spinal control mechanisms, were assessed. RESULTS: The touch reduced all trajectories, mainly of the Rambling component and with closed eyes. There was a floor effect of the touch force as amplitudes and velocities were minimal at 4 N of force. SIGNIFICANCE: The component of postural sway under the supraspinal neural control is more affected by different force magnitudes applied to the touch bar.

Anodal transcranial direct current stimulation over the posterior parietal cortex reduces the onset time to the rubber hand illusion and increases the body ownership.

The body ownership induced by the rubber hand illusion (RHI) has been related to a neural network involving a frontal-parietal circuit. Previous functional neuroimaging studies have demonstrated neural activation in the parietal area relative to the multisensory integration processing and to the recalibration of the felt position of body while a ventral premotor cortex activation has been linked to bodily self-attribution during the RHI. Our study aimed to investigate the effects of transcranial direct current stimulation (tDCS) on the posterior parietal cortex (PPC) or on the premotor cortex (PMv) during RHI to address the specific roles of these two brain areas in the illusion. 156 young adult participants (21.2 ± 3.13 years old; all right-handed) were enrolled for this between-subjects design experiment. Participants received anodal, cathodal and sham tDCS in three different sessions on the right PPC or right PMv and experienced visual-tactile stimulation from the brushes touching the rubber hand and their own left hand in synchronous or asynchronous manner. The RHI was quantified by the (1) onset time for the feeling of body ownership of the rubber hand, (2) proprioceptive drift, and (3) questionnaire about the intensity of the illusion as reported by the participant. All subjects felt the RHI during the synchronous condition. However, we found that the illusion onset time can be modulated by the anodal tDCS condition on the PPC: anodal tDCS decreased the illusion onset time and the subjective experience of body ownership. These findings suggest that the parietal area plays a crucial role in the speed of visual and tactile multisensory integration in the RHI and introduce tDCS as technique that can accelerate the time to integrate an artificial body part and increased the perception of body ownership.

Effects of mesenchymal stromal cells on type 1 diabetes mellitus rat muscles.

INTRODUCTION: Type 1 diabetes mellitus (DM) causes marked skeletal muscle atrophy. Mesenchymal stromal cells (MSC) are an attractive therapy to avoid diabetic complications because of their ability to modify the microenvironment at sites of tissue injury. The objective of this study was to evaluate the effects of MSC transplantation on muscle adaptation caused by diabetes. METHODS: DM was induced by streptozotocin (STZ), and the diabetic animals received systemic MSC transplantation. The von Frey test and footprint analysis were used to assess sensation and sensory motor performance, respectively. Tibialis anterior muscles were investigated by morphology; molecular markers atrogin-1/muscle RING-finger protein-1, nuclear factor κB/p38 mitogen-activated protein kinase, tumor necrosis-like weak inducer of apoptosis/fibroblast growth factor-inducible 14, myostatin, myogenic differentiation 1, and insulin-like growth factor 1 were also assessed. RESULTS: MSC transplantation improved sensation and walking performance and also decreased muscle fibrosis in DM rats by modulating atrogenes but did not prevent muscle atrophy. DISCUSSION: MSCs can reduce muscle and functional complications that result from type 1 DM in rats. Muscle Nerve 58: 583-591, 2018.

ATF2, but not ATF3, participates in the maintenance of nerve injury-induced tactile allodynia and thermal hyperalgesia.

Transcription factors are proteins that modulate the transcriptional rate of target genes in the nucleus in response to extracellular or cytoplasmic signals. Activating transcription factors 2 (ATF2) and 3 (ATF3) respond to environmental signals and maintain cellular homeostasis. There is evidence that inflammation and nerve injury modulate ATF2 and ATF3 expression. However, the function of these transcription factors in pain is unknown. The purpose of this study was to investigate the contribution of ATF2 and ATF3 to nerve injury-induced neuropathic pain. L5/6 spinal nerve ligation induced tactile allodynia and thermal hyperalgesia. Moreover, nerve damage enhanced ATF2 and ATF3 protein expression in injured L5/6 dorsal root ganglia and spinal cord but not in uninjured L4 dorsal root ganglia. Nerve damage also enhanced ATF2 immunoreactivity in dorsal root ganglia and spinal cord 7 to 21 days post-injury. Repeated intrathecal post-treatment with a small-interfering RNA targeted against ATF2 (ATF2 siRNA) or anti-ATF2 antibody partially reversed tactile allodynia and thermal hyperalgesia. In contrast, ATF3 siRNA or anti-ATF3 antibody did not modify nociceptive behaviors. ATF2 immunoreactivity was found in dorsal root ganglia and spinal cord co-labeling with NeuN mainly in non-peptidergic (IB4+) but also in peptidergic (CGRP+) neurons. ATF2 was found mainly in small- and medium-sized neurons. These results suggest that ATF2, but not ATF3, is found in strategic sites related to spinal nociceptive processing and participates in the maintenance of neuropathic pain in rats.