Friction Dynamics of Straight, Curly, and Wavy Hair.

Hair shape affects the frictional properties and tactile sensation of hair. In this study, we evaluated the friction associated with the rubbing of straight, curly, or wavy hair by a contact probe equipped in a sinusoidal motion friction evaluation system. This system provides dynamic information such as the velocity dependence and hysteresis of the frictional force. In the case of hair fibers fixed at 1 mm intervals on a glass plate, a stable friction pattern was observed, in which the friction coefficient was almost constant during the dynamic friction process. The friction coefficients in the inward direction toward the hair root for straight, curly, and wavy hair were 0.47 ± 0.04, 0.51 ± 0.02, and 0.54 ± 0.04, respectively. As wavy hair is thick and has a larger true contact area with the contact probe, the friction coefficient was larger. When the finger model rubbed the straight or curly hair bundle in the inward direction, an oscillation pattern was observed, with the friction coefficient fluctuating at 20 ms intervals and the kinetic friction coefficient evaluated at 0.67 and 0.64, respectively. For the surface of straight hair, containing densely arranged cuticles, a large oscillation was observed in the direction against the cuticles. Meanwhile, no oscillation phenomenon was observed in wavy hair, which is characterized by a smooth cuticle and complex hair flow. Because wavy hair, which is frizzy, has fewer points of contact between hairs, impeding the occurrence of cooperative fluctuations in the frictional force.

Some, but not all, cochlear implant users prefer music stimuli with congruent haptic stimulation.

Cochlear implant (CI) users often report being unsatisfied by music listening through their hearing device. Vibrotactile stimulation could help alleviate those challenges. Previous research has shown that musical stimuli was given higher preference ratings by normal-hearing listeners when concurrent vibrotactile stimulation was congruent in intensity and timing with the corresponding auditory signal compared to incongruent. However, it is not known whether this is also the case for CI users. Therefore, in this experiment, we presented 18 CI users and 24 normal-hearing listeners with five melodies and five different audio-to-tactile maps. Each map varied the congruence between the audio and tactile signals related to intensity, fundamental frequency, and timing. Participants were asked to rate the maps from zero to 100, based on preference. It was shown that almost all normal-hearing listeners, as well as a subset of the CI users, preferred tactile stimulation, which was congruent with the audio in intensity and timing. However, many CI users had no difference in preference between timing aligned and timing unaligned stimuli. The results provide evidence that vibrotactile music enjoyment enhancement could be a solution for some CI users; however, more research is needed to understand which CI users can benefit from it most.

Helping Blind People Grasp: Evaluating a Tactile Bracelet for Remotely Guiding Grasping Movements.

The problem of supporting visually impaired and blind people in meaningful interactions with objects is often neglected. To address this issue, we adapted a tactile belt for enhanced spatial navigation into a bracelet worn on the wrist that allows visually impaired people to grasp target objects. Participants' performance in locating and grasping target items when guided using the bracelet, which provides direction commands via vibrotactile signals, was compared to their performance when receiving auditory instructions. While participants were faster with the auditory commands, they also performed well with the bracelet, encouraging future development of this system and similar systems.

Caring touch as communication in intensive care nursing: a qualitative study.

PURPOSE: This article describes intensive care nurses` experiences of using communicative caring touch as stroking the patient`s cheek or holding his hand. Our research question: "What do intensive care nurses communicate through caring touch?" METHODS: In this qualitative hermeneutically based study data from two intensive care units at Norwegian hospitals are analysed. Eight specialist nurses shared experiences through individual, semi-structured interviews. RESULTS: The main theme, Communicating safety and presence has four sub-themes: Amplified presence, Communicating security, trust and care, Creating and confirming relationships and Communicating openness to a deeper conversation. Communicative caring touch is offered from the nurse due to the patient`s needs. Caring touch communicates person-centred care, invites to relationship while respecting the patient's dignity as a fellow human being. Caring touch conveys a human initiative in the highly technology environment. CONCLUSION: Caring touch is the silent way to communicate care, hope, strength and humanity to critical sick patients. This article provides evidence for a common, but poorly described phenomenon in intensive care nursing.

Spike timing-based coding in neuromimetic tactile system enables dynamic object classification.

Rapid processing of tactile information is essential to human haptic exploration and dexterous object manipulation. Conventional electronic skins generate frames of tactile signals upon interaction with objects. Unfortunately, they are generally ill-suited for efficient coding of temporal information and rapid feature extraction. In this work, we report a neuromorphic tactile system that uses spike timing, especially the first-spike timing, to code dynamic tactile information about touch and grasp. This strategy enables the system to seamlessly code highly dynamic information with millisecond temporal resolution on par with the biological nervous system, yielding dynamic extraction of tactile features. Upon interaction with objects, the system rapidly classifies them in the initial phase of touch and grasp, thus paving the way to fast tactile feedback desired for neuro-robotics and neuro-prosthetics.

Toward more naturalistic tactile sensors.

An artificial tactile system mimicking human touch enables effective object recognition.

Dynamic changes in somatosensory and cerebellar activity mediate temporal recalibration of self-touch.

An organism's ability to accurately anticipate the sensations caused by its own actions is crucial for a wide range of behavioral, perceptual, and cognitive functions. Notably, the sensorimotor expectations produced when touching one's own body attenuate such sensations, making them feel weaker and less ticklish and rendering them easily distinguishable from potentially harmful touches of external origin. How the brain learns and keeps these action-related sensory expectations updated is unclear. Here we employ psychophysics and functional magnetic resonance imaging to pinpoint the behavioral and neural substrates of dynamic recalibration of expected temporal delays in self-touch. Our psychophysical results reveal that self-touches are less attenuated after systematic exposure to delayed self-generated touches, while responses in the contralateral somatosensory cortex that normally distinguish between delayed and nondelayed self-generated touches become indistinguishable. During the exposure, the ipsilateral anterior cerebellum shows increased activity, supporting its proposed role in recalibrating sensorimotor predictions. Moreover, responses in the cingulate areas gradually increase, suggesting that as delay adaptation progresses, the nondelayed self-touches trigger activity related to cognitive conflict. Together, our results show that sensorimotor predictions in the simplest act of touching one's own body are upheld by a sophisticated and flexible neural mechanism that maintains them accurate in time.

Tactile adaptation to orientation produces a robust tilt aftereffect and exhibits crossmodal transfer when tested in vision.

Orientation processing is one of the most fundamental functions in both visual and somatosensory perception. Converging findings suggest that orientation processing in both modalities is closely linked: somatosensory neurons share a similar orientation organisation as visual neurons, and the visual cortex has been found to be heavily involved in tactile orientation perception. Hence, we hypothesized that somatosensation would exhibit a similar orientation adaptation effect, and this adaptation effect would be transferable between the two modalities, considering the above-mentioned connection. The tilt aftereffect (TAE) is a demonstration of orientation adaptation and is used widely in behavioural experiments to investigate orientation mechanisms in vision. By testing the classic TAE paradigm in both tactile and crossmodal orientation tasks between vision and touch, we were able to show that tactile perception of orientation shows a very robust TAE, similar to its visual counterpart. We further show that orientation adaptation in touch transfers to produce a TAE when tested in vision, but not vice versa. Additionally, when examining the test sequence following adaptation for serial effects, we observed another asymmetry between the two conditions where the visual test sequence displayed a repulsive intramodal serial dependence effect while the tactile test sequence exhibited an attractive serial dependence. These findings provide concrete evidence that vision and touch engage a similar orientation processing mechanism. However, the asymmetry in the crossmodal transfer of TAE and serial dependence points to a non-reciprocal connection between the two modalities, providing further insights into the underlying processing mechanism.

Intelligent perceptual textiles based on ionic-conductive and strong silk fibers.

Endowing textiles with perceptual function, similar to human skin, is crucial for the development of next-generation smart wearables. To date, the creation of perceptual textiles capable of sensing potential dangers and accurately pinpointing finger touch remains elusive. In this study, we present the design and fabrication of intelligent perceptual textiles capable of electrically responding to external dangers and precisely detecting human touch, based on conductive silk fibroin-based ionic hydrogel (SIH) fibers. These fibers possess excellent fracture strength (55 MPa), extensibility (530%), stable and good conductivity (0.45 S·m-1) due to oriented structures and ionic incorporation. We fabricated SIH fiber-based protective textiles that can respond to fire, water, and sharp objects, protecting robots from potential injuries. Additionally, we designed perceptual textiles that can specifically pinpoint finger touch, serving as convenient human-machine interfaces. Our work sheds new light on the design of next-generation smart wearables and the reshaping of human-machine interfaces.

Tactile shape discrimination for moving stimuli.

In this study, we explored spatial-temporal dependencies and their impact on the tactile perception of moving objects. Building on previous research linking visual perception and human movement, we examined if an imputed motion mechanism operates within the tactile modality. We focused on how biological coherence between space and time, characteristic of human movement, influences tactile perception. An experiment was designed wherein participants were stimulated on their right palm with tactile patterns, either ambiguous (incongruent conditions) or non-ambiguous (congruent conditions) relative to a biological motion law (two-thirds power law) and asked to report perceived shape and associated confidence. Our findings reveal that introducing ambiguous tactile patterns (1) significantly diminishes tactile discrimination performance, implying motor features of shape recognition in vision are also observed in the tactile modality, and (2) undermines participants' response confidence, uncovering the accessibility degree of information determining the tactile percept's conscious representation. Analysis based on the Hierarchical Drift Diffusion Model unveiled the sensitivity of the evidence accumulation process to the stimulus's informational ambiguity and provides insight into tactile perception as predictive dynamics for reducing uncertainty. These discoveries deepen our understanding of tactile perception mechanisms and underscore the criticality of predictions in sensory information processing.

Grasping objects with the aid of haptics.

A smart suction cup uses haptics to supplement vision for exploration of objects in a grasping task.

Fluid face but not gender: Enfacement illusion through digital face filters does not affect gender identity.

It has been shown that observing a face being touched or moving in synchrony with our own face increases self-identification with the former which might alter both cognitive and affective processes. The induction of this phenomenon, termed enfacement illusion, has often relied on laboratory tools that are unavailable to a large audience. However, digital face filters applications are nowadays regularly used and might provide an interesting tool to study similar mechanisms in a wider population. Digital filters are able to render our faces in real time while changing important facial features, for example, rendering them more masculine or feminine according to normative standards. Recent literature using full-body illusions has shown that participants' own gender identity shifts when embodying a different gendered avatar. Here we studied whether participants' filtered faces, observed while moving in synchrony with their own face, may induce an enfacement illusion and if so, modulate their gender identity. We collected data from 35 female and 33 male participants who observed a stereotypically gender mismatched version of themselves either moving synchronously or asynchronously with their own face on a screen. Our findings showed a successful induction of the enfacement illusion in the synchronous condition according to a questionnaire addressing the feelings of ownership, agency and perceived similarity. However, we found no evidence of gender identity being modulated, neither in explicit nor in implicit measures of gender identification. We discuss the distinction between full-body and facial processing and the relevance of studying widely accessible devices that may impact the sense of a bodily self and our cognition, emotion and behaviour.

First-sight recognition of touched objects shows that chicks can solve Molyneux's problem.

If a congenitally blind person learns to distinguish between a cube and a sphere by touch, would they immediately recognize these objects by sight once their vision is restored? This question, posed by Molyneux in 1688, has puzzled philosophers and scientists since then. To overcome ethical and practical difficulties in the investigation of cross-modal recognition, we studied inexperienced poultry chicks, which can be reared in darkness until the moment of a visual test with no detrimental consequences. After hatching chicks in darkness, we exposed them to either tactile smooth or tactile bumpy stimuli for 24 h. Immediately after the tactile exposure, chicks were tested in a visual recognition task, during their first experience with light. At first sight, chicks that had been exposed in the tactile modality to smooth stimuli approached the visual smooth stimulus significantly more than those exposed to the tactile bumpy stimuli. These results show that visually inexperienced chicks can solve Molyneux's problem, indicating cross-modal recognition does not require previous multimodal experience. At least in this precocial species, supra-modal brain areas appear functional already at birth. This discovery paves the way for the investigation of predisposed cross-modal cognition that does not depend on visual experience.

Evaluation of the neuromotor ability of the tongue in pediatric patients using a stereognostic examination.

BACKGROUND: The term "stereognosis" comes from neurology and describes the capacity to distinguish objects solely by touch. AIM: The aim of this research study was to compare the neuromotor ability of the tongue in patients with malocclusion and tongue dysfunction with and without superficial anesthesia on the tip of the tongue and hard palate. MATERIALS AND METHODS: The study included 132 patients aged 6-13 years. Using a spatula for speech therapy and a visual evaluation while swallowing saliva, all individuals were identified as having swallowing dysfunctions and divided into three groups: study group (children with malocclusions and tongue dysfunctions) - 44 patients, comparator group (children with malocclusions and without tongue dysfunctions) - 44 patients, and control group (children without malocclusions or tongue dysfunctions) - 44 patients. The Koczorowski methods were used for the stereognostic tests. RESULTS: Age, sex, and malocclusion were taken into account during the differential analysis. The study and comparison groups, study and control groups, and the comparator and control groups all showed statistically significant differences from one another. According to the results, tongue dysfunction affects patients' ability to coordinate their movements with their senses at a developing stage. CONCLUSION: Patients with malocclusions that are made worse by tongue dysfunctions have poorer oral stereognostic sensibility. Speech therapy and interdisciplinary specialist orthodontic treatment are required for individuals with impaired oral perception who are still in the developmental stage and have abnormal tongue position and function.

A primary sensory cortical interareal feedforward inhibitory circuit for tacto-visual integration.

Tactile sensation and vision are often both utilized for the exploration of objects that are within reach though it is not known whether or how these two distinct sensory systems combine such information. Here in mice, we used a combination of stereo photogrammetry for 3D reconstruction of the whisker array, brain-wide anatomical tracing and functional connectivity analysis to explore the possibility of tacto-visual convergence in sensory space and within the circuitry of the primary visual cortex (VISp). Strikingly, we find that stimulation of the contralateral whisker array suppresses visually evoked activity in a tacto-visual sub-region of VISp whose visual space representation closely overlaps with the whisker search space. This suppression is mediated by local fast-spiking interneurons that receive a direct cortico-cortical input predominantly from layer 6 neurons located in the posterior primary somatosensory barrel cortex (SSp-bfd). These data demonstrate functional convergence within and between two primary sensory cortical areas for multisensory object detection and recognition.

Differences by Race in Outcomes of an In-Person Training Intervention on Use of an Inpatient Portal: A Secondary Analysis of a Randomized Clinical Trial.

Importance: Differences in patient use of health information technologies by race can adversely impact equitable access to health care services. While this digital divide is well documented, there is limited evidence of how health care systems have used interventions to narrow the gap. Objective: To compare differences in the effectiveness of patient training and portal functionality interventions implemented to increase portal use among racial groups. Design, Setting, and Participants: This secondary analysis used data from a randomized clinical trial conducted from December 15, 2016, to August 31, 2019. Data were from a single health care system and included 6 noncancer hospitals. Participants were patients who were at least 18 years of age, identified English as their preferred language, were not involuntarily confined or detained, and agreed to be provided a tablet to access the inpatient portal during their stay. Data were analyzed from September 1, 2022, to October 31, 2023. Interventions: A 2 × 2 factorial design was used to compare the inpatient portal training intervention (touch, in-person [high] vs built-in video tutorial [low]) and the portal functionality intervention (technology, full functionality [full] vs a limited subset of functions [lite]). Main Outcomes and Measures: Primary outcomes were inpatient portal use, measured by frequency and comprehensiveness of use, and use of specific portal functions. A logistic regression model was used to test the association of the estimators with the comprehensiveness use measure. Outcomes are reported as incidence rate ratios (IRRs) for the frequency outcomes or odds ratios (ORs) for the comprehensiveness outcomes with corresponding 95% CIs. Results: Of 2892 participants, 550 (19.0%) were Black individuals, 2221 (76.8%) were White individuals, and 121 (4.2%) were categorized as other race (including African, American Indian or Alaska Native, Asian or Asian American, multiple races or ethnicities, and unknown race or ethnicity). Black participants had a significantly lower frequency (IRR, 0.80 [95% CI, 0.72-0.89]) of inpatient portal use compared with White participants. Interaction effects were not observed between technology, touch, and race. Among participants who received the full technology intervention, Black participants had lower odds of being comprehensive users (OR, 0.76 [95% CI, 0.62-0.91), but interaction effects were not observed between touch and race. Conclusions and Relevance: In this study, providing in-person training or robust portal functionality did not narrow the divide between Black participants and White participants with respect to their inpatient portal use. Health systems looking to narrow the digital divide may need to consider intentional interventions that address underlying issues contributing to this inequity. Trial Registration: ClinicalTrials.gov Identifier: NCT02943109.

Cortical activations associated with spatial remapping of finger touch using EEG.

The spatial coding of tactile information is functionally essential for touch-based shape perception and motor control. However, the spatiotemporal dynamics of how tactile information is remapped from the somatotopic reference frame in the primary somatosensory cortex to the spatiotopic reference frame remains unclear. This study investigated how hand position in space or posture influences cortical somatosensory processing. Twenty-two healthy subjects received electrical stimulation to the right thumb (D1) or little finger (D5) in three position conditions: palm down on right side of the body (baseline), hand crossing the body midline (effect of position), and palm up (effect of posture). Somatosensory-evoked potentials (SEPs) were recorded using electroencephalography. One early-, two mid-, and two late-latency neurophysiological components were identified for both fingers: P50, P1, N125, P200, and N250. D1 and D5 showed different cortical activation patterns: compared with baseline, the crossing condition showed significant clustering at P1 for D1, and at P50 and N125 for D5; the change in posture showed a significant cluster at N125 for D5. Clusters predominated at centro-parietal electrodes. These results suggest that tactile remapping of fingers after electrical stimulation occurs around 100-125 ms in the parietal cortex.

Cortical cellular encoding of thermotactile integration.

Recent evidence suggests that primary sensory cortical regions play a role in the integration of information from multiple sensory modalities. How primary cortical neurons integrate different sources of sensory information is unclear, partly because non-primary sensory input to a cortical sensory region is often weak or modulatory. To address this question, we take advantage of the robust representation of thermal (cooling) and tactile stimuli in mouse forelimb primary somatosensory cortex (fS1). Using a thermotactile detection task, we show that the perception of threshold-level cool or tactile information is enhanced when they are presented simultaneously, compared with presentation alone. To investigate the cortical cellular correlates of thermotactile integration, we performed in vivo extracellular recordings from fS1 in awake resting and anesthetized mice during unimodal and bimodal stimulation of the forepaw. Unimodal stimulation evoked thermal- or tactile- specific excitatory and inhibitory responses of fS1 neurons. The most prominent features of combined thermotactile stimulation are the recruitment of unimodally silent fS1 neurons, non-linear integration features, and response dynamics that favor longer response durations with additional spikes. Together, we identify quantitative and qualitative changes in cortical encoding that may underlie the improvement in perception of thermotactile surfaces during haptic exploration.