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The dazzling sensitivity and frequency selectivity of the vertebrate ear rely on mechanical amplification of the hair cells’ responsiveness to small stimuli. As revealed by spontaneous oscillations and forms of mechanical excitability in response to force steps, the hair bundle that adorns each hair cell is both a mechanosensory antenna and a force generator that might participate in the amplificatory process. To study the various incarnations of active hair-bundle motility, we combined Ca 2+ iontophoresis with mechanical stimulation of single hair bundles from the bullfrog’s sacculus. We identified three classes of active hair-bundle movements: a hair bundle could be quiescent but display nonmonotonic twitches in response to either excitatory or inhibitory force steps, or oscillate spontaneously. Extracellular Ca 2+ changes could affect the kinetics of motion and, when large enough, evoke transitions between the three classes of motility. We found that the Ca 2+-dependent location of a bundle’s operating point within its force-displacement relation controlled the type of movement observed. In response to an iontophoretic pulse of Ca 2+ or of a Ca 2+ chelator, a hair bundle displayed a movement whose polarity could be reversed by applying a static bias to the bundle’s position at rest. Moreover, such polarity reversal was accompanied by a 10-fold change in the kinetics of the Ca 2+-evoked hair-bundle movement. A unified theoretical description, in which mechanical activity stems solely from myosin-based adaptation, could account for the fast and slow manifestations of active hair-bundle motility observed in frog, as well as in auditory organs of the turtle and the rat.

Kangaroo mother care (KMC) is an evidence-based approach to reducing mortality and morbidity in preterm infants. Although KMC is a key intervention package in newborn health initiatives, there is limited systematic information available on the barriers to KMC practice that mothers and other stakeholders face while practicing KMC. This systematic review sought to identify the most frequently reported barriers to KMC practice for mothers, fathers, and health practitioners, as well as the most frequently reported enablers to practice for mothers. We searched nine electronic databases and relevant reference lists for publications reporting barriers or enablers to KMC practice. We identified 1,264 unique publications, of which 103 were included based on pre-specified criteria. Publications were scanned for all barriers / enablers. Each publication was also categorized based on its approach to identification of barriers / enablers, and more weight was assigned to publications which had systematically sought to understand factors influencing KMC practice. Four of the top five ranked barriers to KMC practice for mothers were resource-related: \"Issues with the facility environment / resources,\" \"negative impressions of staff attitudes or interactions with staff,\" \"lack of help with KMC practice or other obligations,\" and \"low awareness of KMC / infant health.\" Considering only publications from low- and middle-income countries, \"pain / fatigue\" was ranked higher than when considering all publications. Top enablers to practice were included \"mother-infant attachment\" and \"support from family, friends, and other mentors.\" Our findings suggest that mother can understand and enjoy KMC, and it has benefits for mothers, infants, and families. However, continuous KMC may be physically and emotionally difficult, and often requires support from family members, health practitioners, or other mothers. These findings can serve as a starting point for researchers and program implementers looking to improve KMC programs.

Localization of objects and events in the environment is critical for survival, as many perceptual and motor tasks rely on estimation of spatial location. Therefore, it seems reasonable to assume that spatial localizations should generally be accurate. Curiously, some previous studies have reported biases in visual and auditory localizations, but these studies have used small sample sizes and the results have been mixed. Therefore, it is not clear (1) if the reported biases in localization responses are real (or due to outliers, sampling bias, or other factors), and (2) whether these putative biases reflect a bias in sensory representations of space or a priori expectations (which may be due to the experimental setup, instructions, or distribution of stimuli). Here, to address these questions, a dataset of unprecedented size (obtained from 384 observers) was analyzed to examine presence, direction, and magnitude of sensory biases, and quantitative computational modeling was used to probe the underlying mechanism(s) driving these effects. Data revealed that, on average, observers were biased towards the center when localizing visual stimuli, and biased towards the periphery when localizing auditory stimuli. Moreover, quantitative analysis using a Bayesian Causal Inference framework suggests that while pre-existing spatial biases for central locations exert some influence, biases in the sensory representations of both visual and auditory space are necessary to fully explain the behavioral data. How are these opposing visual and auditory biases reconciled in conditions in which both auditory and visual stimuli are produced by a single event? Potentially, the bias in one modality could dominate, or the biases could interact/cancel out. The data revealed that when integration occurred in these conditions, the visual bias dominated, but the magnitude of this bias was reduced compared to unisensory conditions. Therefore, multisensory integration not only improves the precision of perceptual estimates, but also the accuracy.

•MR-compatible hand-adaptive multichannel device for tactile stimulation.•Somatotopic maps of the human hand in primary somatosensory cortex in between- and within-digit dimensions using 7T fMRI.•Somatotopic map in random order paradigm verified the leading function of the thumb compared to other fingers. The 7T functional magnetic resonance imaging (fMRI) can provide a detailed somatotopic map. However, due to the constraints of MR-compatible applications, current tactile stimulation devices for the human hand are insufficient for precise somatotopic mapping experiments. In this study, we developed a novel 23-channel, hand-adaptive tactile stimulation device with high temporal and spatial resolution. The device consisted of an execution module and a control module. The device's output performance was measured using a laser displacement sensor. We investigated the somatotopic map of the non-dominant hand in the primary somatosensory cortex (S1) using the Bayesian population receptive field (pRF) model. The activation patterns, relative volumes, and activation center locations on S1 were assessed in somatotopic mapping experiments involving traveling wave stimulus paradigms with three stimulus orders (forward, backward, and random) in two dimensions (between-digit and within-digit). The percussive stimulation provided by the tactile stimulation device exhibited a stable displacement (2.58 mm) and a minimal output delay (4.45 milliseconds) across a wide range of vibration frequencies (0–30 Hz). The representation of digits and the palm in the between-digit dimension showed consistent somatotopic organization (D1-D2-D3-D4-D5-palm along the postcentral gyrus (poCG) from ventral to dorsal) across all three stimulation orders. Additionally, the relative volume of D1 in the random paradigm was significantly larger than in the forward and backward paradigms. The relative volume of the palm in the random paradigm was significantly larger than in the backward paradigm. The representation of the phalanges and palm in the within-digit dimension exhibited different activation patterns across different stimulation orders. These results provide new insights into the neural mechanisms in S1 and validate that the developed stimulation device can contribute to exploring the somatotopic map of the human hand.

Low frequency ultrasound (<1 MHz) has been demonstrated to be a promising approach for non-invasive neuro-stimulation. However, the focal width is limited to be half centimeter scale. Minimizing the stimulation region with higher frequency ultrasound will provide a great opportunity to expand its application. This study first time examines the feasibility of using high frequency (5 MHz) ultrasound to achieve neuro-stimulation in brain and verifies the anatomical specificity of neuro-stimulation in vivo . 1 MHz and 5 MHz ultrasound stimulation were evaluated in the same group of mice. Electromyography (EMG) collected from tail muscles together with the motion response videos were analyzed for evaluating the stimulation effects. Our results indicate that 5 MHz ultrasound can successfully achieve neuro-stimulation. The equivalent diameter (ED) of the stimulation region with 5 MHz ultrasound (0.29 ± 0.08 mm) is significantly smaller than that with 1 MHz (0.83 ± 0.11 mm). The response latency of 5 MHz ultrasound (45 ± 31 ms) is also shorter than that of 1 MHz ultrasound (208 ± 111 ms). Consequently, high frequency (5 MHz) ultrasound can successfully activate the brain circuits in mice. It provides a smaller stimulation region, which offers improved anatomical specificity for neuro-stimulation in a non-invasive manner.

Objective To determine if a simple stimulation method increases the rate of infant voiding for clean catch urine within five minutes.Design Randomised controlled trial.Setting Emergency department of a tertiary paediatric hospital, Australia.Participants 354 infants (aged 1-12 months) requiring urine sample collection as determined by the treating clinician. 10 infants were subsequently excluded.Interventions Infants were randomised to either gentle suprapubic cutaneous stimulation (n=174) using gauze soaked in cold fluid (the Quick-Wee method) or standard clean catch urine with no additional stimulation (n=170), for five minutes.Main outcome measures The primary outcome was voiding of urine within five minutes. Secondary outcomes were successful collection of a urine sample, contamination rate, and parental and clinician satisfaction with the method.Results The Quick-Wee method resulted in a significantly higher rate of voiding within five minutes compared with standard clean catch urine (31% v 12%, P<0.001), difference in proportions 19% favouring Quick-Wee (95% confidence interval for difference 11% to 28%). Quick-Wee had a higher rate of successful urine sample collection (30% v 9%, P<0.001) and greater parental and clinician satisfaction (median 2 v 3 on a 5 point Likert scale, P<0.001). The difference in contamination between Quick-Wee and standard clean catch urine was not significant (27% v 45%, P=0.29). The number needed to treat was 4.7 (95% confidence interval 3.4 to 7.7) to successfully collect one additional urine sample within five minutes using Quick-Wee compared with standard clean catch urine.Conclusions Quick-Wee is a simple cutaneous stimulation method that significantly increases the five minute voiding and success rate of clean catch urine collection.Trial registration Australian New Zealand Clinical Trials Registry ACTRN12615000754549.

Much work has been devoted to the elucidation of pain signaling, whereas the transduction of pleasant touch has garnered less attention. In this study, the authors present data suggesting that pleasant touch is mediated by a particular dedicated type of peripheral nerve fibers, the low-threshold, unmyelinated mechanoreceptive C-tactile afferents. Pleasant touch sensations may begin with neural coding in the periphery by specific afferents. We found that during soft brush stroking, low-threshold unmyelinated mechanoreceptors (C-tactile), but not myelinated afferents, responded most vigorously at intermediate brushing velocities (1−10 cm s −1 ), which were perceived by subjects as being the most pleasant. Our results indicate that C-tactile afferents constitute a privileged peripheral pathway for pleasant tactile stimulation that is likely to signal affiliative social body contact.

To address the low repeatability and accuracy of traditional technologies for testing the human somatosensory system, this work presents a novel mechatronic testbed. The testbed allows for the delivery of mechanical and thermal stimuli with a high spatial resolution, enabling continuous or discrete stimulation with a small fixed area and in a single experimental session. The testbed was employed to identify the mechanical/thermal innocuous and painful thresholds and the human ability to distinguish the nature of a painful stimulus, on both the hand and the forearm of 12 healthy volunteers. The results demonstrated the capability of the developed testbed to produce a range of forces that can induce different sensations (touch or pain). We found a statistical difference between the innocuous and painful thresholds, regardless of the tested anatomical spot. In this paper, a small thermal stimulation tip was appositely selected to study the reaction to a focused thermal stimulus that has been poorly investigated so far. The results highlighted a statistically significant difference between the two stimulated sites for the cool sensation and the hot pain. Moreover, the painful recognition task was sped up by the use of the developed testbed, which allowed a more fair comparison among the applied stimuli, increasing the accuracy, repeatability, and consistency when compared to the state-of-the art.

As technology continues towards smaller, thinner and lighter devices, more stringent demands are placed on thin polymer films as diffusion barriers, dielectric coatings, electronic packaging and so on. Therefore, there is a growing need for testing platforms to rapidly determine the mechanical properties of thin polymer films and coatings. We introduce here an elegant, efficient measurement method that yields the elastic moduli of nanoscale polymer films in a rapid and quantitative manner without the need for expensive equipment or material-specific modelling. The technique exploits a buckling instability that occurs in bilayers consisting of a stiff, thin film coated onto a relatively soft, thick substrate. Using the spacing of these highly periodic wrinkles, we calculate the film's elastic modulus by applying well-established buckling mechanics. We successfully apply this new measurement platform to several systems displaying a wide range of thicknessess (nanometre to micrometre) and moduli (MPa to GPa).

For most multisensory events, observers perceive synchrony among the various senses (vision, audition, touch), despite the naturally occurring lags in arrival and processing times of the different information streams. A substantial amount of research has examined how the brain accomplishes this. In the present article, we review several key issues about intersensory timing, and we identify four mechanisms of how intersensory lags might be dealt with: by ignoring lags up to some point (a wide window of temporal integration), by compensating for predictable variability, by adjusting the point of perceived synchrony on the longer term, and by shifting one stream directly toward the other.