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Integrating sensors and other functional parts in one device can enable a new generation of integrated intelligent devices that can perform self‐sensing and monitoring autonomously. Applications include buildings that detect and repair damage, robots that monitor conditions and perform real‐time correction and reconstruction, aircraft capable of real‐time perception of the internal and external environment, and medical devices and prosthetics with a realistic sense of touch. Although integrating sensors and other functional parts into self‐sensing intelligent devices has become increasingly common, additive manufacturing has only been marginally explored. This review focuses on additive manufacturing integrated design, printing equipment, and printable materials and stuctures. The importance of the material, structure, and function of integrated manufacturing are highlighted. The study summarizes current challenges to be addressed and provides suggestions for future development directions. [ABSTRACT FROM AUTHOR]

Abstract Integrating sensors and other functional parts in one device can enable a new generation of integrated intelligent devices that can perform self‐sensing and monitoring autonomously. Applications include buildings that detect and repair damage, robots that monitor conditions and perform real‐time correction and reconstruction, aircraft capable of real‐time perception of the internal and external environment, and medical devices and prosthetics with a realistic sense of touch. Although integrating sensors and other functional parts into self‐sensing intelligent devices has become increasingly common, additive manufacturing has only been marginally explored. This review focuses on additive manufacturing integrated design, printing equipment, and printable materials and stuctures. The importance of the material, structure, and function of integrated manufacturing are highlighted. The study summarizes current challenges to be addressed and provides suggestions for future development directions.

Abstract Proprioceptors are non‐nociceptive low‐threshold mechanoreceptors. However, recent studies have shown that proprioceptors are acid‐sensitive and express a variety of proton‐sensing ion channels and receptors. Accordingly, although proprioceptors are commonly known as mechanosensing neurons that monitor muscle contraction status and body position, they may have a role in the development of pain associated with tissue acidosis. In clinical practice, proprioception training is beneficial for pain relief. Here we summarize the current evidence to sketch a different role of proprioceptors in ‘non‐nociceptive pain’ with a focus on their acid‐sensing properties.

Proprioceptors are non‐nociceptive low‐threshold mechanoreceptors. However, recent studies have shown that proprioceptors are acid‐sensitive and express a variety of proton‐sensing ion channels and receptors. Accordingly, although proprioceptors are commonly known as mechanosensing neurons that monitor muscle contraction status and body position, they may have a role in the development of pain associated with tissue acidosis. In clinical practice, proprioception training is beneficial for pain relief. Here we summarize the current evidence to sketch a different role of proprioceptors in 'non‐nociceptive pain' with a focus on their acid‐sensing properties. What is the topic of this review?Why proprioceptors, which are non‐nociceptive, low‐threshold mechanosensory neurons that monitor muscle contraction and body position, express several proton‐sensing ion channels and receptors.What advances does it highlight?ASIC3 is a dual function protein for proton‐sensing and mechano‐sensing in proprioceptors that can be activated by eccentric muscle contraction or lactic acidosis. A role is proposed for proprioceptors in non‐nociceptive unpleasantness (or sng), which is associated with their acid‐sensing properties, in chronic musculoskeletal pain. [ABSTRACT FROM AUTHOR]

This article presents evidence indicating that intracranial pressure (ICP) pulsatility, associated with the heartbeat and breathing, is not just a source of mechanical artefact in electrical recordings, but is "sensed" and plays a role in the brain's information processing. Patch-clamp recording of pressure-activated channels, and detection of Piezo2-protein channel expression in brain neurons, suggest that these channels provide neurons with an intrinsic resonance to ICP pulsatility, which acts to synchronize remote neural networks. Direct measurements in human patients indicate that heartbeat and breathing rhythms generate intracranial forces of tens of millinewtons, exceeding by orders of magnitude the localized forces shown by atomic force microscopy and optical tweezers to activate Piezo channels in isolated neocortical and hippocampal neurons. Additionally, many human touch and proprioceptors, which are also transduced by Piezo channels, show spiking that is phase-locked to heartbeat- and breathing-induced extracranial pressure pulsations. Finally, based on the observation that low-frequency oscillations modulate the phase and amplitude of high-frequency oscillations, body and brain oscillations are proposed to form a single hierarchical system in which the heartbeat is the basic frequency and scaling factor for all other oscillations. Together, these results support the idea that ICP pulsatility may be elemental in modulating the brain's electrical rhythmicity. [ABSTRACT FROM AUTHOR]

Proprioceptors are low-threshold mechanoreceptors involved in perceiving body position and strain bearing. However, the physiological response of proprioceptors to fatigue- and muscle-acidosis-related disturbances remains unknown. Here, we employed whole-cell patch-clamp recordings to probe the effect of mild acidosis on the mechanosensitivity of the proprioceptive neurons of dorsal root ganglia (DRG) in mice. We cultured neurite-bearing parvalbumin-positive (Pv+) DRG neurons on a laminin-coated elastic substrate and examined mechanically activated currents induced through substrate deformation-driven neurite stretch (SDNS). The SDNS-induced inward currents (ISDNS) were indentation depth-dependent and significantly inhibited by mild acidification (pH 7.2~6.8). The acid-inhibiting effect occurred in neurons with an ISDNS sensitive to APETx2 (an ASIC3-selective antagonist) inhibition, but not in those with an ISNDS resistant to APETx2. Detailed subgroup analyses revealed ISDNS was expressed in 59% (25/42) of Parvalbumin-positive (Pv+) DRG neurons, 90% of which were inhibited by APETx2. In contrast, an acid (pH 6.8)-induced current (IAcid) was expressed in 76% (32/42) of Pv+ DRG neurons, 59% (21/32) of which were inhibited by APETx2. Together, ASIC3-containing channels are highly heterogenous and differentially contribute to the ISNDS and IAcid among Pv+ proprioceptors. In conclusion, our findings highlight the importance of ASIC3-containing ion channels in the physiological response of proprioceptors to acidic environments. [ABSTRACT FROM AUTHOR]

Somatosensory neurons in dorsal root ganglia (DRG) comprise several main subclasses: high threshold nociceptors/thermoceptors, high- and low-threshold mechanoreceptors, and proprioceptors. Recent years have seen an explosion in the identification of molecules that underlie the functional diversity of these sensory modalities. They also have begun to reveal the developmental mechanisms that channel the emergence of this subtype diversity, solidifying the importance of peripheral instructive signals. Somatic sensory neurons collectively serve numerous essential physiological and protective roles, and as such, an increased understanding of the processes that underlie the specialization of these sensory subtypes is not only biologically interesting but also clinically relevant. [ABSTRACT FROM AUTHOR]

Introduction: In the sports field, the use of proprioceptive training is an effective method in optimizing athletes' performances. For this reason, we thought also to try this method also in the field of physical education, namely in the physical education lesson in a public school. Our intention was to organize an intervention through a physical exercise program that would stimulate the proprioceptors in order to improve the sensory-motor function of children. We wanted to observe and highlight whether students can express what they feel when they do exercise. Before starting to practice, the students were instructed by the physical education teacher to focus on the signals received from the external and internal environment of the body, e.g., proprioceptive, or tactile information in the absence of visual information. Purpose: The purpose of this study was to highlight the level of awareness in children during physical exercise in order to evaluate and compare it with other children. Methods: bibliographic study; observation method; the Likert scale tool; the method of comparing the results; data collection; graphing and data analysis and interpretation. Results: The subjects of this research were a total of 74 students, of which 48 children from the 4th grade and 26 children from the 7th grade, enrolled in a public school in Bucharest. We created a chart, which we have distributed to the students, and measured their level of awareness immediately after they finished their exercise. Conclusions: There are large differences between the 4th grade and the 7th grade students in terms of the results obtained. Thus, the 4th grade children aged 10 were much more aware of what they were feeling than the 7th grade children aged 13. [ABSTRACT FROM AUTHOR]

Basic science and clinical evidence suggest that cervical spine disorders can lead to dizziness. The cervical spine has highly developed proprioceptive receptors, whose input information is integrated with the visual and vestibular systems in the central nervous system, acting on the neck and eye muscles to maintain the coordinative motion of the head, eyes, neck, and body through various reflex activities. When the cervical proprioceptive input changes due to the mismatch or conflict between vestibular, visual, and proprioceptive inputs, cervicogenic dizziness may occur. The diagnosis of cervicogenic dizziness can be determined based on clinical features, diagnostic tests, and the exclusion of other possible sources of dizziness. The cervical torsion test appears to be the best diagnostic method for cervicogenic dizziness. Based on the available evidence, we first developed the diagnostic criteria for cervicogenic dizziness. Treatment for cervicogenic dizziness is similar to that for neck pain, and manual therapy is most widely recommended. [ABSTRACT FROM AUTHOR]

To better personalize treatment and monitor recovery of individuals with low back pain, objective tests of sensorimotor functions, such as lumbar proprioception, must be selected based on their reliability and validity. The primary objective of this study was to test the concurrent validity of three measures of lumbar proprioception. Thirty-one participants performed three lumbar proprioception tests (motion perception threshold, active and passive joint positioning sense), a whole-body mobility and balance (time up-and-go) and two trunk-specific postural control (threshold of stability and sensor-based sway measures) tests. Only the motion perception threshold proprioception test showed some validity, correlating with the trunk-specific postural control tests [r range (positive values): 0.37 to 0.60]. The three lumbar proprioception measures were not correlated to each other. The threshold of stability measure was correlated with the time up-and-go (r = 0.37) and trunk-specific (sensor-based sway measures) postural control [r range (positive values): 0.48 to 0.77] tests. The present study generated three original findings. Only the motion perception threshold proprioception test demonstrated its concurrent validity. In fact, the three lumbar proprioception tests performed in the present study were not correlated to each other, thus assessing different constructs. Finally, the threshold of stability protocol was validated against other tests. These findings will help in selecting the most appropriate lumbar proprioception measures to study the effects of exercise treatments in patients with back pain. [ABSTRACT FROM AUTHOR]

This article presents evidence indicating that intracranial pressure (ICP) pulsatility, associated with the heartbeat and breathing, is not just a source of mechanical artefact in electrical recordings, but is “sensed” and plays a role in the brain’s information processing. Patch-clamp recording of pressure-activated channels, and detection of Piezo2-protein channel expression in brain neurons, suggest that these channels provide neurons with an intrinsic resonance to ICP pulsatility, which acts to synchronize remote neural networks. Direct measurements in human patients indicate that heartbeat and breathing rhythms generate intracranial forces of tens of millinewtons, exceeding by orders of magnitude the localized forces shown by atomic force microscopy and optical tweezers to activate Piezo channels in isolated neocortical and hippocampal neurons. Additionally, many human touch and proprioceptors, which are also transduced by Piezo channels, show spiking that is phase-locked to heartbeat- and breathing-induced extracranial pressure pulsations. Finally, based on the observation that low-frequency oscillations modulate the phase and amplitude of high-frequency oscillations, body and brain oscillations are proposed to form a single hierarchical system in which the heartbeat is the basic frequency and scaling factor for all other oscillations. Together, these results support the idea that ICP pulsatility may be elemental in modulating the brain’s electrical rhythmicity.

Proprioceptors are low-threshold mechanoreceptors involved in perceiving body position and strain bearing. However, the physiological response of proprioceptors to fatigue- and muscle-acidosis-related disturbances remains unknown. Here, we employed whole-cell patch-clamp recordings to probe the effect of mild acidosis on the mechanosensitivity of the proprioceptive neurons of dorsal root ganglia (DRG) in mice. We cultured neurite-bearing parvalbumin-positive (Pv+) DRG neurons on a laminin-coated elastic substrate and examined mechanically activated currents induced through substrate deformation-driven neurite stretch (SDNS). The SDNS-induced inward currents (ISDNS) were indentation depth-dependent and significantly inhibited by mild acidification (pH 7.2~6.8). The acid-inhibiting effect occurred in neurons with an ISDNS sensitive to APETx2 (an ASIC3-selective antagonist) inhibition, but not in those with an ISNDS resistant to APETx2. Detailed subgroup analyses revealed ISDNS was expressed in 59% (25/42) of Parvalbumin-positive (Pv+) DRG neurons, 90% of which were inhibited by APETx2. In contrast, an acid (pH 6.8)-induced current (IAcid) was expressed in 76% (32/42) of Pv+ DRG neurons, 59% (21/32) of which were inhibited by APETx2. Together, ASIC3-containing channels are highly heterogenous and differentially contribute to the ISNDS and IAcid among Pv+ proprioceptors. In conclusion, our findings highlight the importance of ASIC3-containing ion channels in the physiological response of proprioceptors to acidic environments.

Introduction/Aim: The anterior cruciate ligament (ACL) of the knee joint is one of the most investigated structures of the musculoskeletal system. Numerous studies are dedicated to the macro- and micro anatomy of human and animal ACL, but not many are focused on the proprioceptors of the ligament. The aim of this study was to establish a relationship between the proprioceptors and the stage of degenerative changes in the ACL. Materials and Methods: Sixty ACL were harvested from patients admitted for knee replacement surgery. The samples were processed, histochemically and immunohistochemically stained according to standard laboratory protocols. Results were analysed and interpreted. The research was approved by the Ethics Committee of Medical University Pleven. Results: Fifty-seven patients were included in our study – 37 females and 20 males. The average age of patients was 66.48 years. Degeneration of ACL was classified in four stages, and four different patterns of degeneration were observed: 1) necrosis and inflammation; 2) myxoid and cystic formation; 3) vascularisation with myxoid changes; 4) inflammation and hyalinosis. With the increasing severity of degeneration, the number of specialized nervous structures diminish. Discussion: Our findings support the results from studies on animal models, conducted by other authors. Cabuk et al. reported a diminishing number of proprioceptors in the PCL of an osteoarthritic human knee.The lower number of proprioceptors could result in the onset or progression of the arthritic process. Conclusion: Osteoarthritis involves all elements of the knee joint. Altered proprioception could be the reason for unsatisfied patients with artificial knees.

Basic science and clinical evidence suggest that cervical spine disorders can lead to dizziness. The cervical spine has highly developed proprioceptive receptors, whose input information is integrated with the visual and vestibular systems in the central nervous system, acting on the neck and eye muscles to maintain the coordinative motion of the head, eyes, neck, and body through various reflex activities. When the cervical proprioceptive input changes due to the mismatch or conflict between vestibular, visual, and proprioceptive inputs, cervicogenic dizziness may occur. The diagnosis of cervicogenic dizziness can be determined based on clinical features, diagnostic tests, and the exclusion of other possible sources of dizziness. The cervical torsion test appears to be the best diagnostic method for cervicogenic dizziness. Based on the available evidence, we first developed the diagnostic criteria for cervicogenic dizziness. Treatment for cervicogenic dizziness is similar to that for neck pain, and manual therapy is most widely recommended.

Mechanical vibration, applied to single or few muscles, can be a selective stimulus for muscle spindles, able to modify neuromuscular management, inducing short and long-term effects, are now mainly employed in clinic studies. Several studies reported as treatments with focal vibratory (FVT) can influence neuromuscular parameters also in healthy people. However, the application modalities and the consequent effects are remarkably fragmented. This paper aims to review these studies and to characterize the FVT effectiveness on long-term conditional capacities in relation to FVT characteristics. A systematic search of studies published from 1985 to 2020 in English on healthcare databases was performed. Articles had to meet the following criteria: (1) treatment based on a locally applied vibration on muscle belly or tendon; (2) healthy adults involved; (3) outcomes time analysis enduring for more than 24 h. Twelve studies were found, all of them presented an excellent quality score of ≥75%. All selected papers reported positive changes, comparable with traditional long-lasting training effects. Muscle force and power were the most investigated parameters. The after-effects persisted for up to several months. Among the different FV administration modalities, the most effective seems to show a stimulus frequency of ≈100 Hz, repeated more times within three-five days on a voluntary contracted muscle. [ABSTRACT FROM AUTHOR]

Soft robots are considered to have infinite degrees of freedom based on their structural compliance, providing high adaptability to the environments, and recent study has focused mostly on advancement of their physical designs for increasing the adaptability. However, interaction itself with the environment has not been taken into serious account in previous studies despite the importance in applications. A soft robot as a hybrid system described by both discrete and continuous states is considered and a method of analysis for enhanced manipulation is proposed. The method is tested with a soft gripper composed of a pneumatic bending actuator and an embedded soft sensor for a task of object gripping. The optimum sensor location on the actuator based on the calibration map obtained from the actuator characterization is first determined. Using the sensor information, the interaction with the environment (i.e., object) classified into four discrete states is understood. In addition, a control strategy to find the best position to grip the object based on the estimated states is developed. The gripper is able to successfully complete the task using the proposed method for three test scenarios with different initial conditions and control parameters. Finally, the results are demonstrated with supporting videos.

Soft robots are considered to have infinite degrees of freedom based on their structural compliance, providing high adaptability to the environments, and recent study has focused mostly on advancement of their physical designs for increasing the adaptability. However, interaction itself with the environment has not been taken into serious account in previous studies despite the importance in applications. A soft robot as a hybrid system described by both discrete and continuous states is considered and a method of analysis for enhanced manipulation is proposed. The method is tested with a soft gripper composed of a pneumatic bending actuator and an embedded soft sensor for a task of object gripping. The optimum sensor location on the actuator based on the calibration map obtained from the actuator characterization is first determined. Using the sensor information, the interaction with the environment (i.e., object) classified into four discrete states is understood. In addition, a control strategy to find the best position to grip the object based on the estimated states is developed. The gripper is able to successfully complete the task using the proposed method for three test scenarios with different initial conditions and control parameters. Finally, the results are demonstrated with supporting videos. [ABSTRACT FROM AUTHOR]

Background: The quality of proprioception, which we classify as Gnostic functions, affects a person's physical performance. Sports performance requires a good perception of one's own body, a sufficient ability to control one's body and keep it as stable as possible in space. The purpose: The purpose of the research was to compare the state of Gnostic and balance abilities between different sports disciplines, in comparison with the control group. Methods: 80 probands of both genders, aged 18-30 years, were divided into 7 groups of 10, according to sports discipline. The last control group consisted of 10 probands who did not perform any sport. Active athletes were selected for the research, involved in the highest competition of their discipline from various sports: sprint, athletic walking, throws, long jumps, judo, basketball and ice hockey. For the diagnosis of gnostic functions, tests were chosen to examine the modalities of kinesthesia, somatognosis and stereognosis. To test the equilibrium functions, 6 tests using BOSU with both, visual and non-visual control were used. Results: Results at the level of statistical significance at the level of p = 0.05 were demonstrated between the groups of jumpers and basketball players in the kinesthesia test and in the somatognosis test between all athletes and the control group. The stereognosis test showed significant differences between all groups except the sprinter and basketball players. In the equilibrium tests, a statistically significant difference was shown only in the test of standing on both lower limbs without visual control, between the groups of sprinters and the control group, sprinters and basketball players and between the control group and all athletes together. Conclusions: Based on the results, we can say that there are significant differences in some proprioceptive and equilibrium modalities in different sports. We assume that the type of sport can have an impact on the quality of these functions [ABSTRACT FROM AUTHOR]

Human induced pluripotent stem cells (iPSCs) are used to generate models of human diseases that recapitulate the pathogenic process as it occurs in affected cells. Many differentiated cell types can currently be obtained from iPSCs, but no validated protocol is yet available to specifically generate primary proprioceptive neurons. Proprioceptors are affected in a number of genetic and acquired diseases, including Friedreich ataxia (FRDA). To develop a cell model that can be applied to conditions primarily affecting proprioceptors, we set up a protocol to differentiate iPSCs into primary proprioceptive neurons. We modified the dual-SMAD inhibition/WNT activation protocol, previously used to generate nociceptor-enriched cultures of primary sensory neurons from iPSCs, to favor instead the generation of proprioceptors. We succeeded in substantially enriching iPSC-derived primary sensory neuron cultures for proprioceptors, up to 50% of finally differentiated neurons, largely exceeding the proportion of 7.5% normally represented by these cells in dorsal root ganglia. We also showed that almost pure populations of proprioceptors can be purified from these cultures by fluorescence-activated cell sorting. Finally, we demonstrated that the protocol can be used to generate proprioceptors from iPSCs from FRDA patients, providing a cell model for this genetic sensory neuronopathy. [ABSTRACT FROM AUTHOR]

The purpose of this study was to investigate the functional decline in proprioceptors in patients with low back pain (LBP) by evaluating the entire range of response frequencies of proprioceptors. In previous studies, the function of proprioceptors was only evaluated by single frequency vibrations. However, because it is assumed that individual differences exist in response frequencies of proprioceptors, we developed a method using vibration with sweep frequency covering the entire range of response frequencies of proprioceptors. The center of pressure was determined in 35 elderly patients with non-specific LBP (NSLBP) and 28 elderly individuals with non-LBP (NLBP) during upright stances on a balance board without vision. Local vibratory stimulations to lower leg or trunk muscles were continuously varied between 27 and 272 Hz over 60 s to evaluate the proprioceptive predominance of a body location using the relative proprioceptive weighting ratio (RPW). Compared with the NLBP group, the NSLBP group exhibited a lower RPW value for the Vater-Pacini corpuscles. Thus, the NSLBP group relied more on the input of Vater-Pacini corpuscles in the trunk. A reduction in lower leg sensitivity at the Vater-Pacini corpuscles in the NSLBP group was observed. [ABSTRACT FROM AUTHOR]

Proprioception is a quality of sensibility that originates in specialized sensory organs (proprioceptors) that inform the central nervous system about static and dynamic conditions of muscles and joints. The facial muscles are innervated by efferent motor nerve fibers and typically lack proprioceptors. However, facial proprioception plays a key role in the regulation and coordination of the facial musculature and diverse reflexes. Thus, facial muscles must be necessarily supplied also for afferent sensory nerve fibers provided by other cranial nerves, especially the trigeminal nerve. Importantly, neuroanatomical studies have demonstrated that facial proprioceptive impulses are conveyed through branches of the trigeminal nerve to the central nervous system. The multiple communications between the facial and the trigeminal nerves are at the basis of these functional characteristics. Here we review the literature regarding the facial (superficial) communications between the facial and the trigeminal nerves, update the current knowledge about proprioception in the facial muscles, and hypothesize future research in facial proprioception.

Objectives. The research aims to present the proprioception in the football game at the age of 10 - 12 years, structured on its main components: balance, neuromuscular coordination and speed. Methods. The pedagogical experiment was conducted on a team of children in the city of Braşov, with a correlation between the level of their technical executions and the balance, coordination and speed indicators of the players. In the initial and final testing, specific research equipment was used and the subjects were being tested on the "bosu ball" for the neuromuscular coordination component, on the balance equilibrium platform for balance indices. Two test specimens specific to the football game were used for the moral quality indexes. Results. The processing of the results from the final test revealed a direct correlation between the „bosu ball" indices, equilibrium indices (equilibrium platform) and the level recorded in the two specific speedshifting tests. The results are presented in the tables being processed statistically and mathematically. Conclusions. The conclusions of the scientific research confirmed the hypotheses of research, highlighting regarding proprioception, direct correlations between the subjects balance, their neuromuscular coordination and the motric quality indexes. [ABSTRACT FROM AUTHOR]

The number, location and morphology of intersegmental descending interneurons, which connect pro- and mesothoracic ganglia with the matathoracic ganglion in the cockroach Periplaneta americana, were investigated herein using a retrograde nickel chloride tracing through one of the connectives that link meso- and metathoracic ganglia. The bodies of stained neurons were aggregated into clusters lying ether ipsilaterally or contralaterally to the axon through which the dye was delivered. Differences in size, architecture and dendrite ramification of ipsi- and contralateral neurons were described. Ipsilateral neurons ramified also ipsilaterally, whereas contralateral neurons formed ramifications on the both sides of the ganglion. The data obtained suggest that adjustment of the walking pattern generator by sensory input from legs is mainly achieved through ipsilateral descending neurons, while adaptation to the environment and brain commands is accomplished through contralateral neurons. [ABSTRACT FROM AUTHOR]

The article reports on proprioceptive reflexes and their involvement in developing the motor skills. It discusses several proprioceptive mechanisms and their applications in movement. These proprioceptors are categorized into three groups, muscle proprioceptors, proprioceptors of joints and skin, and labyrinthine and neck proprioceptors. Proprioceptive facilitation and inhibition techniques are used by physical therapists in rehabilitation of patients with neuromuscular disabilities, and can also be used to improve the motor performance of healthy individuals.

The purpose of this study was to investigate the functional decline in proprioceptors in patients with low back pain (LBP) by evaluating the entire range of response frequencies of proprioceptors. In previous studies, the function of proprioceptors was only evaluated by single frequency vibrations. However, because it is assumed that individual differences exist in response frequencies of proprioceptors, we developed a method using vibration with sweep frequency covering the entire range of response frequencies of proprioceptors. The center of pressure was determined in 35 elderly patients with non-specific LBP (NSLBP) and 28 elderly individuals with non-LBP (NLBP) during upright stances on a balance board without vision. Local vibratory stimulations to lower leg or trunk muscles were continuously varied between 27 and 272 Hz over 60 s to evaluate the proprioceptive predominance of a body location using the relative proprioceptive weighting ratio (RPW). Compared with the NLBP group, the NSLBP group exhibited a lower RPW value for the Vater-Pacini corpuscles. Thus, the NSLBP group relied more on the input of Vater-Pacini corpuscles in the trunk. A reduction in lower leg sensitivity at the Vater-Pacini corpuscles in the NSLBP group was observed.

Highlights • Rats were subjected to daily exercise for 16–18 weeks. • Large and small rat DRG neurons were separated using laser capture microdissection. • Daily exercise altered gene expression in rat lumbar DRG neurons. • Small and large DRG neurons often showed different responses to exercise. • Daily treadmill and voluntary wheel activity elicited different responses. Abstract The purpose of this study was to determine the response, in rat, to chronic physical activity in small and large DRG neurons. Rats were cage-confined or underwent 16–18 weeks of daily increased activity, via 2 h of treadmill running per day or free access to voluntary exercise wheels, following which small (≤30 µm) and large (≥40 µm) diameter DRG neurons were harvested by laser capture microdissection from flash-frozen lumbar DRGs. Relative mRNA levels were determined using real-time polymerase chain reaction. Following chronic treadmill and voluntary wheel exercise, gene expression responses in neurons mostly differed between exercise types. Changes in both small and large DRG neurons included increases in opioid receptor mu subunit (MOR), NGF and GAP43, and decreases in 5HT1A, TrkA, TrkB, and delta-type opioid receptor (DOR) mRNAs. In small DRG neurons, treadmill exercise increased the expression of mRNA for 5HT1D and decreased expression for 5HT1F receptors. In large DRG neurons, voluntary wheel exercise decreased the expression for 5HT1D receptors, whereas both treadmill and voluntary wheel exercise decreased the expression of mRNA for TrkC receptors. DRG neurons show slightly more changes in gene expression after voluntary exercise compared to the treadmill exercise group. Small and large lumbar sensory neurons are responsive to chronically increased neuromuscular activity by changing the expression of genes, the products of which could potentially change the sensory processing of nociceptors and proprioceptors, which could in turn alter functions such as pain transmission and locomotor coordination. [ABSTRACT FROM AUTHOR]

Inhibitory afferent inputs to pontine A5 noradrenergic neurons (A5 NN) are not known, except partial baroreceptor input. In spontaneously breathing pentobarbital-anesthetized rats, we registered 35 A5 NN that were activated by hypoxia (100% N2, 10 sec) by more than 5 times in comparison with the background. Cooling of retrotrapezoid nucleus (15°C, 6 sec) completely blocked the motor inspiratory output and A5 NN discharge frequency increased (23/23) by more than 7 times in comparison with the background values. The beginning of A5 NN activation coincided with cessation of inspiratory activity. Short-term passive stretching of the shin muscles (1 sec, 100 g) caused BP drop and complete inhibition of A5 NN (12/12) activated by hypoxia. Inhibitory afferent inputs from proprioceptors and central inspiratory neurons that can limit A5 NN activity were demonstrated. [ABSTRACT FROM AUTHOR]

Sensory information conveyed along afferent fibers from muscle and joint proprioceptors play an important role in the control of posture and gait in humans. In particular, proprioceptive information from the neck is fundamental in supplying the central nervous system with information about the orientation and movement of the head relative to the rest of the body. The previous studies have confirmed that proprioceptive afferences originating from the neck region, evoked via muscle vibration, lead to strong body-orienting effects during static conditions (e.g., leaning of the body forwards or backwards, depending on location of vibration). However, it is not yet certain in humans, whether the somatosensory receptors located in the deep skin (cutaneous mechanoreceptors) have a substantive contribution to postural control, as vibratory stimulation encompasses the receptive field of all the somatosensory receptors from the skin to the muscles. The aim of this study was to investigate the postural effect of cutaneous mechanoreceptor afferences using electro-tactile stimulation applied to the neck. Ten healthy volunteers (8M, 2F) were evaluated. The average position of their centre of foot pressure (CoP) was acquired before, during, and after a subtle electro-tactile stimulation over their posterior neck (mean ± SD = 5.1 ± 2.3 mA at 100 Hz—140% of the perception threshold) during upright stance with their eyes closed. The electro-tactile stimulation led to a body-orienting effect with the subjects consistently leaning forward. An average shift of the CoP of 12.1 ± 11.9 mm (mean ± SD) was reported, which significantly (p < 0.05) differed from its average position under a control condition (no stimulation). These results indicate that cutaneous mechanoreceptive inflow from the neck is integrated to control stance. The findings are relevant for the exploitation of electro-tactile stimulation for rehabilitation interventions where induced anteropulsion of the body is desired. [ABSTRACT FROM AUTHOR]

In practice, a single test is used to quantify an individual's proprioception. Previous studies have not found a correlation between joint position sense (JPS) and force sense (FS), which are submodalities of proprioception. The purpose of the present study is to determine if root mean square (RMS) error in JPS and FS are related at the shoulder, controlling for external load and elevation angle. Active shoulder angle and force reproduction protocols were performed. No correlation was found between JPS and FS (r = –.019,p =.941) nor were any individual angle and load combinations significant. The main effect for angle in JPS was significant (p <.001). Follow-up contrast demonstrated a significant (p <.001) decrease in RMS error with increased elevation. A significant load by angle interaction was found for FS (p =.014). Follow-up simple effects tests by angle demonstrated RMS error decreased with load at 50° and 70° but not at 90°. By load, RMS error only decreased for 120% between 50° and 90°. JPS and FS demonstrate different behavior with load and angle. This differing behavior is more likely responsible for the lack of correlation than angle and load differences in JPS and FS protocols. [ABSTRACT FROM PUBLISHER]

Analysing the causes of cerebral motor infirmity (CMI) in patients, it has been concluded -- actually, generally admitted that the following factors contribute to the complexity of remarked aspects: sensory disorders of different levels, spasticity, disorder of the postural reflex mechanism, lack of selective movement modalities. Sensory disorders are, in the majority of cases, the result of increased muscle tone. Increased tone and uncoordinated movements determine monstrous sensory images in the proprioceptors, which increase, in their turn, motor disorder. Each of these factors has its characteristics and specific features. There are methods that can help us in the treatment of CMI. We will present a point of view on some of them. Therapeutic education (Le Metayer -- a relaxation technique for the spastic upper limb, without the intervention of global ways, which was proposed by Bobath), where Matieu and subsequently Le Metayer introduce the association between the terms of education and therapy; global stimulation (Vojta); Kabat method -- appeared as a refinement of Kenny's method. [ABSTRACT FROM AUTHOR]

Study Design: Electrophysiological recordings were obtained from proprioceptors in deep lumbar paraspinal muscles of anesthetized cats during high-velocity low-amplitude spinal manipulation (HVLA-SM).Objective: To determine how thrust direction of an HVLA-SM affects neural input from back musculature.Summary Of Background Data: A clinician's ability to apply the thrust of an HVLA-SM in a specified direction is considered an important component of its optimal delivery. However, previous biomechanical studies indicate that the shear force component of the thrust vector is not actually transmitted to paraspinal tissues deep to the thoracolumbar fascia because the skin-fascia interface is frictionless.Methods: Neural activity from muscle spindles in the multifidus and longissimus muscles was recorded from L6 dorsal rootlets in 18 anesthetized cats. After preload to the spinal tissues, HVLA-SMs (100-ms thrust duration) were applied through the intact skin overlying the L6 lamina. Thrusts were applied at angles oriented perpendicularly to the back and obliquely at 15° and 30° medialward or cranialward using a 6 × 6 Latin square design with three replicates. The normal force component was kept constant at 21.3 N. HVLA-SMs were preceded and followed by simulated spinal movement applied to the L6 vertebra. Changes in mean instantaneous discharge frequency (ΔMIF) of muscle spindles were determined both during the thrust and spinal movement.Results: ΔMIFs during the HVLA-SM thrust were significantly greater in response to all thrust directions compared with the preload alone, but there was no difference in ΔMIF for any of the thrust directions during the HVLA-SM. HVLA-SM decreased some of the responses to simulated spinal movement but thrust direction had no effect on these changes.Conclusion: The shear force component of an HVLA-SM's thrust vector is not transmitted to the underlying vertebra sufficient to activate muscle spindles of the attached muscles. Implications for clinical practice and clinical research are discussed.Level Of Evidence: N/A. [ABSTRACT FROM AUTHOR]

Brainstem and cerebellar neurons implement an internal model to accurately estimate self-motion during externally generated ('passive') movements. However, these neurons show reduced responses during self-generated ('active') movements, indicating that predicted sensory consequences of motor commands cancel sensory signals. Remarkably, the computational processes underlying sensory prediction during active motion and their relationship to internal model computations during passive movements remain unknown. We construct a Kalman filter that incorporates motor commands into a previously established model of optimal passive self-motion estimation. The simulated sensory error and feedback signals match experimentally measured neuronal responses during active and passive head and trunk rotations and translations. We conclude that a single sensory internal model can combine motor commands with vestibular and proprioceptive signals optimally. Thus, although neurons carrying sensory prediction error or feedback signals show attenuated modulation, the sensory cues and internal model are both engaged and critically important for accurate self-motion estimation during active head movements. [ABSTRACT FROM AUTHOR]

The proprioceptive, visual and vestibular sensory systems interact to maintain dynamic stability during movement. The relative importance and interplay between these sensory systems is still not fully understood. Increased knowledge about spatial perception and postural orientation would provide better understanding of balance disorders, and their rehabilitation. Displacement of the body in space was recorded in 16 healthy subjects performing a sequence of stepping-in-place tests without any visual or auditory cues. Spatial displacement and orientation in space were determined by calculating two parameters, 'Moved distance (sagittal + lateral displacement)' and 'Rotation'. During the stepping-in-place tests vibration were applied in a randomized order on four different cervical muscles, and the effects were compared between muscles and to a non-vibration baseline condition. During the tests a forward displacement ('Moved distance') was found to be the normal behavior, with various degrees of longitudinal rotation ('Rotation'). The moved distance was significantly larger when the vibration was applied on the dorsal muscles (916 mm) relative to on ventral muscles (715 mm) ( p = 0.003) and the rate of displacement was significantly larger for dorsal muscles (36.5 mm/s) relative to ventral (28.7 mm/s) vs ( p = 0.002). When vibration was applied on the left-sided muscles, 16° rotation to the right was induced ( p = 0.005), whereas no significant rotation direction was induced with right-sided vibration (3°). The rate of rotation was significantly larger for vibration applied on ventral muscles (0.44°/s) relative to on dorsal (0.33°/s) ( p = 0.019). The results highlight the influence of cervical proprioception on the internal spatial orientation, and subsequent for postural control. [ABSTRACT FROM AUTHOR]

In terrestrial vertebrates such as birds and mammals, neurotrophin receptor expression is considered fundamental for the specification of distinct somatosensory neuron types where Traka, TrkB and TrkC specify nociceptors, mechanoceptors and proprioceptors/mechanoceptors, respectively. In turn, Runx transcription factors promote neuronal fate specification by regulating neurotrophin receptor and sensory receptor expression where Runx1 mediates TrkA+ nociceptor diversification while Runx3 promotes a TrkC+ proprioceptive/mechanoceptive fate. Here, we report in zebrafish larvae that orthologs of the neurotrophin receptors in contrast to terrestrial vertebrates mark overlapping and distinct subsets of nociceptors suggesting that TrkA, TrkB and TrkC do not intrinsically promote nociceptor, mechanoceptor and proprioceptor/mechanoceptor neuronal fates, respectively. While we find that zebrafish Runx3 regulates nociceptors in contrast to terrestrial vertebrates, it shares a conserved regulatory mechanism found in terrestrial vertebrate proprioceptors/mechanoceptors in which it promotes TrkC expression and suppresses TrkB expression. We find that Cbfβ, which enhances Runx protein stability and affinity for DNA, serves as an obligate cofactor for Runx in neuronal fate determination. High levels of Runx can compensate for the loss of Cbfβ, indicating that in this context Cbfβ serves solely as a signal amplifier of Runx activity. Our data suggests an alteration/expansion of the neurotrophin receptor code of sensory neurons between larval teleost fish and terrestrial vertebrates, while the essential roles of Runx/Cbfβ in sensory neuron cell fate determination while also expanded are conserved. [ABSTRACT FROM AUTHOR]

Elhers-Danlos syndrome (EDS) is the clinical manifestation of connective tissue disorders, and comprises several clinical forms with no specific symptoms and selective medical examinations which result in a delay in diagnosis of about 10 years. The EDS hypermobility type (hEDS) is characterized by generalized joint hypermobility, variable skin hyperextensibility and impaired proprioception. Since somatosensory processing and multisensory integration are crucial for both perception and action, we put forth the hypothesis that somatosensory deficits in hEDS patients may lead, among other clinical symptoms, to misperception of verticality and postural instability. Therefore, the purpose of this study was twofold: (i) to assess the impact of somatosensory deficit on subjective visual vertical (SVV) and postural stability; and (ii) to quantify the effect of wearing somatosensory orthoses (i.e., compressive garments and insoles) on postural stability. Six hEDS patients and six age- and gender-matched controls underwent a SVV (sitting, standing, lying on the right side) evaluation and a postural control evaluation on a force platform (Synapsys), with or without visual information (eyes open (EO)/eyes closed (EC)). These two latter conditions performed either without orthoses, or with compression garments (CG), or insoles, or both. Results showed that patients did not exhibit a substantial perceived tilt of the visual vertical in the direction of the body tilt (Aubert effect) as did the control subjects. Interestingly, such differential effects were only apparent when the rod was initially positioned to the left of the vertical axis (opposite the longitudinal body axis). In addition, patients showed greater postural instability (sway area) than the controls. The removal of vision exacerbated this instability, especially in the mediolateral (ML) direction. The wearing of orthoses improved postural stability, especially in the eyes-closed condition, with a particularly marked effect in the anteroposterior (AP) direction. Hence, this study suggests that hEDS is associated with changes in the relative contributions of somatosensory and vestibular inputs to verticality perception. Moreover, postural control impairment was offset, at least partially, by wearing somatosensory orthoses. [ABSTRACT FROM AUTHOR]

Recent research on proprioception reveals that it relies on a systematically distorted model of bodily dimensions. This generates a puzzle about proprioception in action control: action requires accurate bodily parameters. Proprioception is crucial for ordinary action, but if it relies on a systematically distorted body model, then proprioception should contain systematic errors. But we cannot respond by discarding proprioception from motor control, since we know from the severe problems deafferented agents face in acting that ordinary action requires proprioception. The solution is that the possibility of bodily action is provided for by multimodal body representations for action (the 'body schema'). [ABSTRACT FROM AUTHOR]

Neuronal cell identity is established during development and must be maintained throughout an animal’s life (Fishell G, Heintz N. Neuron 80: 602–612, 2013). Transcription factors critical for establishing neuronal identity can be required for maintaining it (Deneris ES, Hobert O. Nat Neurosci 17: 899–907, 2014). Posttranscriptional regulation also plays an important role in neuronal differentiation (Bian S, Sun T. Mol Neurobiol 44: 359–373, 2011), but its role in maintaining cell identity is less established. To better understand how posttranscriptional regulation might contribute to cell identity, we examined the proprioceptive neurons in the dorsal root ganglion (DRG), a highly specialized sensory neuron class, with well-established properties that distinguish them from other neurons in the ganglion. By conditionally ablating Dicer in mice, using parvalbumin (Pvalb)-driven Cre recombinase, we impaired posttranscriptional regulation in the proprioceptive sensory neuron population. Knockout (KO) animals display a progressive form of ataxia at the beginning of the fourth postnatal week that is accompanied by a cell death within the DRG. Before cell loss, expression profiling shows a reduction of proprioceptor specific genes and an increased expression of nonproprioceptive genes normally enriched in other ganglion neurons. Furthermore, although central connections of these neurons are intact, the peripheral connections to the muscle are functionally impaired. Posttranscriptional regulation is therefore necessary to retain the transcriptional identity and support functional specialization of the proprioceptive sensory neurons. [ABSTRACT FROM AUTHOR]

The human craniofacial muscles innervated by the facial nerve typically lack muscle spindles. However these muscles have proprioception that participates in the coordination of facial movements. A functional substitution of facial proprioceptors by cutaneous mechanoreceptors has been proposed but at present this alternative has not been demonstrated. Here we have investigated whether other kinds of sensory structures are present in two human facial muscles (zygomatic major and buccal). Human checks were removed from Spanish cadavers, and processed for immunohistochemical detection of nerve fibers (neurofilament proteins and S100 protein) and two putative mechanoproteins (acid-sensing ion channel 2 and transient receptor potential vanilloid 4) associated with mechanosensing. Nerves of different calibers were found in the connective septa and within the muscle itself. In all the muscles analysed, capsular corpuscle-like structures resembling elongated or round Ruffini-like corpuscles were observed. Moreover the axon profiles within these structures displayed immunoreactivity for both putative mechanoproteins. The present results demonstrate the presence of sensory structures in facial muscles that can substitute for typical muscle spindles as the source of facial proprioception. [ABSTRACT FROM AUTHOR]

Suboptimal nutrition imposes developmental constraints on infant animals, which marshal adaptive responses to eventually become mature adults. Such responses are mounted at multiple levels from systemic to cellular. At the cellular level, the underlying mechanisms of cell proliferation control have been intensively studied. However, less is known about how growth of postmitotic and morphologically complex cells, such as neurons, is controlled by nutritional status. We address this question using Class I and Class IV dendritic arborization neurons in Drosophila larvae. Class IV neurons have been shown to sense nociceptive thermal, mechanical and light stimuli, whereas Class I neurons are proprioceptors. We reared larvae on diets with different protein and carbohydrate content throughout larval stages and examined how morphologies of Class I or Class IV neurons were affected. Dendritic arbors of Class IV neurons became more complex when larvae were reared on a low-yeast diet, which contains lower amounts of amino acids and other ingredients, compared to a high-yeast diet. In contrast, such low-yeast-dependent hyperarborization was not seen in Class I neurons. The physiological and metabolic implications of the hyperarborization phenotype are discussed in relation to a recent hypothesis that Class IV neurons sense protein-deficient stress and to our characterization of how the dietary yeast contents impacted larval metabolism. [ABSTRACT FROM AUTHOR]