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Tomography (Ann Arbor, Mich.) Sep 2022Anatomically accurate models of a human finger can be useful in simulating various disorders. In order to have potential clinical value, such models need to include a...
Anatomically accurate models of a human finger can be useful in simulating various disorders. In order to have potential clinical value, such models need to include a large number of tissue types, identified by an experienced professional, and should be versatile enough to be readily tailored to specific pathologies. Magnetic resonance images were acquired at ultrahigh magnetic field (7 T) with a radio-frequency coil specially designed for finger imaging. Segmentation was carried out under the supervision of an experienced radiologist to accurately capture various tissue types (TTs). The final segmented model of the human index finger had a spatial resolution of 0.2 mm and included 6,809,600 voxels. In total, 15 TTs were identified: subcutis, Pacinian corpuscle, nerve, vein, artery, tendon, collateral ligament, volar plate, pulley A4, bone, cartilage, synovial cavity, joint capsule, epidermis and dermis. The model was applied to the conditions of arthritic joint, ruptured tendon and variations in the geometry of a finger. High-resolution magnetic resonance images along with careful segmentation proved useful in the construction of an anatomically accurate model of the human index finger. An example illustrating the utility of the model in biomedical applications is shown. As the model includes a number of tissue types, it may present a solid foundation for future simulations of various musculoskeletal disease processes in human joints.
Topics: Humans; Magnetic Resonance Imaging; Fingers; Radio Waves; Tendons; Tendon Injuries
PubMed: 36287795
DOI: 10.3390/tomography8050196 -
PLoS Biology Aug 2019Motion is an essential component of everyday tactile experience: most manual interactions involve relative movement between the skin and objects. Much of the research on...
Motion is an essential component of everyday tactile experience: most manual interactions involve relative movement between the skin and objects. Much of the research on the neural basis of tactile motion perception has focused on how direction is encoded, but less is known about how speed is. Perceived speed has been shown to be dependent on surface texture, but previous studies used only coarse textures, which span a restricted range of tangible spatial scales and provide a limited window into tactile coding. To fill this gap, we measured the ability of human observers to report the speed of natural textures-which span the range of tactile experience and engage all the known mechanisms of texture coding-scanned across the skin. In parallel experiments, we recorded the responses of single units in the nerve and in the somatosensory cortex of primates to the same textures scanned at different speeds. We found that the perception of speed is heavily influenced by texture: some textures are systematically perceived as moving faster than are others, and some textures provide a more informative signal about speed than do others. Similarly, the responses of neurons in the nerve and in cortex are strongly dependent on texture. In the nerve, although all fibers exhibit speed-dependent responses, the responses of Pacinian corpuscle-associated (PC) fibers are most strongly modulated by speed and can best account for human judgments. In cortex, approximately half of the neurons exhibit speed-dependent responses, and this subpopulation receives strong input from PC fibers. However, speed judgments seem to reflect an integration of speed-dependent and speed-independent responses such that the latter help to partially compensate for the strong texture dependence of the former.
Topics: Adult; Animals; Female; Humans; Macaca mulatta; Male; Motion Perception; Movement; Neurons; Skin; Somatosensory Cortex; Touch; Touch Perception; Young Adult
PubMed: 31454360
DOI: 10.1371/journal.pbio.3000431 -
Journal of Shoulder and Elbow Surgery Apr 2021Sensory receptors in the joint capsule are critical for maintaining joint stability. However, the distribution of sensory receptors in the glenohumeral joint of the...
BACKGROUND AND HYPOTHESES
Sensory receptors in the joint capsule are critical for maintaining joint stability. However, the distribution of sensory receptors in the glenohumeral joint of the shoulder, including mechanoreceptors and free nerve endings, has not been described yet. This study aimed to describe the distributions of different sensory receptor subtypes in the glenohumeral joint capsule. Our hypotheses were as follows: (1) Sensory receptor subtypes would differ in density but follow a similar distribution pattern, and (2) the anterior capsule would have the highest density of sensory receptors.
METHODS
Six glenohumeral joint capsules were harvested from the glenoid to the humeral attachment. The capsule was divided into 4 regions of interest (anterior, posterior, superior, and inferior) and analyzed using modified gold chloride stain. Sensory receptors as well as free nerve endings were identified and counted under a light microscope from sections of each region of interest. The density of each sensory receptor subtype was calculated relative to capsule volume.
RESULTS
Sensory receptors were distributed in the glenohumeral joint capsule with free nerve endings. The anterior capsule exhibited the highest median density of all 4 sensory receptors examined, followed by the superior, inferior, and posterior capsules. The median densities of these sensory receptor subtypes also significantly differed (P = .007), with type I (Ruffini corpuscles) receptors having the highest density (2.97 U/cm), followed by type IV (free nerve endings, 2.25 U/cm), type II (Pacinian corpuscles, 1.40 U/cm), and type III (Golgi corpuscles, 0.24 U/cm) receptors.
CONCLUSION
Sensory receptor subtypes are differentially expressed in the glenohumeral joint capsule, primarily type I and IV sensory receptors. The expression of sensory receptors was dominant in the anterior capsule, stressing the important role of proprioception feedback for joint stability. The surgical procedure for shoulder instability should consider the topography of sensory receptors to preserve or restore the proprioception of the shoulder joint.
Topics: Aged; Cadaver; Female; Humans; Joint Capsule; Joint Instability; Male; Mechanoreceptors; Middle Aged; Nerve Endings; Proprioception; Sensory Receptor Cells; Shoulder Joint
PubMed: 32707328
DOI: 10.1016/j.jse.2020.07.006 -
Attention, Perception & Psychophysics Aug 2020It has been shown that vibrotactile stimuli elicit sound perception either on their own or by enhancing otherwise inaudible sounds. For taking advantage of this...
It has been shown that vibrotactile stimuli elicit sound perception either on their own or by enhancing otherwise inaudible sounds. For taking advantage of this phenomenon in the design of vibrotactile interfaces, it is important to identify its properties with respect to the level of the excitation frequency. The aim of this work is to further substantiate previous research results that indicate a prevalence of this phenomenon at a specific range of frequencies (200-390 Hz), which roughly pertains to the Pacinian corpuscle's maximum sensitivity range. Thirteen young adults participated in the study, which included comparison between sound-and-vibration versus sound-only signals. Masking background noise and no-touch control experiments were included to further support the outcome. The results validate the hypothesis that vibrotactile excitation at the index fingertip can enhance otherwise inaudible tones in the specific range of frequencies.
Topics: Fingers; Humans; Sensory Thresholds; Touch Perception; Vibration; Young Adult
PubMed: 32342343
DOI: 10.3758/s13414-020-02025-y -
Diagnostics (Basel, Switzerland) Jul 2022Plantar fibromatosis, known as Ledderhose disease, is a neoplastic disease characterized by a locally-aggressive bland fibroblastic proliferation. Although Pacinian...
BACKGROUND
Plantar fibromatosis, known as Ledderhose disease, is a neoplastic disease characterized by a locally-aggressive bland fibroblastic proliferation. Although Pacinian corpuscles alterations are commonly described in palmar fibromatosis, there are still no references about Pacinian corpuscles alterations in the rarer plantar version.
METHODS
We present a case report where a wide cutaneous resection, including the plantar fascia was performed, allowing a detailed study of Pacinian corpuscles. Pacinian corpuscles were analyzed using immunohistochemistry for neurofilament proteins, S100 protein, CD34, vimentin, glucose transporter 1, epithelial membrane antigen, neural-cell adhesion molecule, actin, desmin, type IV collagen, and high-affinity neurotrophin Trk-receptors. Moreover, the density and the size of the corpuscles were determined.
RESULTS
A clear increase in the number (hyperplasia) of Pacinian corpuscles was evidenced in the Ledderhose disease plantar fascia in comparison with similarly aged normal subjects. Pacinian hypertrophy was not demonstrated, but a significant decrease in the number of corpuscular lamellae was noted, with a subsequent increase in the interlamellar spaces. Pacinian corpuscles from the pathological plantar fascia showed an abnormal structure and immunohistochemical profile, generally without identifiable axons, and also absence of an inner core or an intermediate layer. Moreover, other molecules related with trophic maintenance of corpuscles were also absent. Finally, a vascular proliferation was commonly noted in some corpuscles, which involved all corpuscular constituents.
CONCLUSION
The observed Pacinian corpuscles hyperplasia could be considered a diagnostic clue of plantar fibromatosis.
PubMed: 35885610
DOI: 10.3390/diagnostics12071705 -
Journal of Pediatric Urology Mar 2024Circumcision is a surgical operation that is frequently performed throughout the world due to religious, cultural, and medical reasons. The best age for circumcision is...
BACKGROUND
Circumcision is a surgical operation that is frequently performed throughout the world due to religious, cultural, and medical reasons. The best age for circumcision is still debatable, with different procedures depending on geography, culture, and surgeon preference.
OBJECTIVE
This study aims to immunohistochemical examination using S100 staining and histologically evaluate the neurovascular structures in foreskin samples obtained from children aged 0-3 years and 6-11 years. The goal is to provide guidance in determining an appropriate age for circumcision based on these data.
STUDY DESIGN
Concerns regarding potential effects on glans sensitivity and sexual function led to the investigation and comparison of sensory innervation in the foreskin of children aged 0-3 and 6-11 years, a total 54 samples, divided into pre-phallic (0-3 years) and post-phallic (6-11 years) groups, were examined. The mean number of Meissner and Pacinian corpuscles, Ruffini endings, free nerve endings and the diameters of arteries were investigated.
RESULTS
Our findings show that compared to the 6-11 age group, the 0-3 age group had considerably lower sensory innervation in terms of, Meissner's corpuscles, Pacinian corpuscles, Ruffini endings and free nerve endings. Additionally, the diameter of arteries was noticeably smaller in the 0-3 age group.
CONCLUSIONS
In conclusion, this study supports the idea that circumcision performed in the early years of life may be associated with less adverse effects on neurovascular structures.
PubMed: 38580481
DOI: 10.1016/j.jpurol.2024.03.016 -
Shoulder & Elbow Aug 2019The topographic arrangement of sensory receptors in the human elbow joint capsule is pertinent to their role in the transmission of neural signals. The signals from...
BACKGROUND
The topographic arrangement of sensory receptors in the human elbow joint capsule is pertinent to their role in the transmission of neural signals. The signals from stimuli in the joint are concisely delivered via afferent pathways to allow recognition of pain and proprioception. Sensory receptors in the elbow joint include mechanoreceptors and free nerve endings acting as nociceptors, although the distribution of each of the structures has not been determined, despite their importance for the integrity of the joint. We therefore aimed to investigate the neuroanatomical distribution and densities of mechanoreceptors and free nerve endings in the capsule of the elbow, at the same time as considering surgical approaches that would result in the minimum insult to them.
METHODS
Four elbow joint capsules were harvested from fresh cadavers. The specimens were carefully separated from adjacent osteoligamentous attachments and the capsular complex was stained with a modified gold chloride method. Evaluations of free nerve endings, and Golgi, Ruffini and Pacinian corpuscles were performed under an inverted light microscope. The number and density of each structure were recorded.
RESULTS
Ruffini corpuscles observed to be the dominant mechanoreceptor type. No Golgi corpuscle was observed. Free nerve endings were found at the highest density at posterodistal sites, whereas mechanoreceptors were most frequent at bony attachment sites.
CONCLUSIONS
A consistent distribution pattern of articular sensory receptors was observed, which allows further understanding of elbow pathology. An awareness of the neuroanatomical distribution of sensory receptors in the elbow joint capsule may allow their preservation during surgical procedures for elbow joint pathology.
PubMed: 31316591
DOI: 10.1177/1758573218760245 -
ENeuro 2021Sensory environments are commonly characterized by specific physical features, which sensory systems might exploit using dedicated processing mechanisms. In the tactile...
Sensory environments are commonly characterized by specific physical features, which sensory systems might exploit using dedicated processing mechanisms. In the tactile sense, one such characteristic feature is frictional movement, which gives rise to short-lasting (<10 ms), information-carrying integument vibrations. Rather than generic integrative encoding (i.e., averaging or spectral analysis capturing the "intensity" and "best frequency"), the tactile system might benefit from, what we call a "temporally local" coding scheme that instantaneously detects and analyzes shapes of these short-lasting features. Here, by employing analytic psychophysical measurements, we tested whether the prerequisite of temporally local coding exists in the human tactile system. We employed pulsatile skin indentations at the fingertip that allowed us to trade manipulation of local pulse shape against changes in global intensity and frequency, achieved by adding pulses of the same shape. We found that manipulation of local pulse shape has strong effects on psychophysical performance, arguing for the notion that humans implement a temporally local coding scheme for perceptual decisions. As we found distinct differences in performance using different kinematic layouts of pulses, we inquired whether temporally local coding is tuned to a unique kinematic variable. This was not the case, since we observed different preferred kinematic variables in different ranges of pulse shapes. Using an established encoding model for primary afferences and indentation stimuli, we were able to demonstrate that the found kinematic preferences in human performance, may well be explained by the response characteristics of Pacinian corpuscles (PCs), a class of human tactile primary afferents.
Topics: Biomechanical Phenomena; Humans; Physical Stimulation; Skin; Touch; Touch Perception; Vibration
PubMed: 34625459
DOI: 10.1523/ENEURO.0263-21.2021 -
Sensors (Basel, Switzerland) Sep 2022The development of gustatory sensors is essential for the development of smart materials for use in robotics, and in the food, beverage, and pharmaceutical industries....
The development of gustatory sensors is essential for the development of smart materials for use in robotics, and in the food, beverage, and pharmaceutical industries. We therefore designed a prototype of a rubber tongue embedded with a gustatory receptor mimicking a human tongue using our previously proposed hybrid fluid rubber (HF rubber) and an electrolytic polymerization technique. The fabricated gustatory receptor was composed of Pacinian corpuscles, which are well known and have already been elucidated as effective haptic and auditory receptors in previous studies. Moreover, the receptor has self-powered voltage generated as built-in electricity as a result of the ionized particles and molecules in the HF rubber. The utilization of a layered structure for the Pacinian corpuscles induced a typical response not only to normal and shear forces but to thermal variations. Typical gustatory characteristics, including the initial response voltage and the cyclic voltammogram form, were clearly varied by five tastes: saltiness, sourness, sweetness, bitterness, and umami. These results were due to ORP, pH, and conductivity.
Topics: Electrolytes; Humans; Polymerization; Rubber; Smart Materials; Taste; Tongue
PubMed: 36146328
DOI: 10.3390/s22186979 -
Experimental Brain Research Dec 2021Single cutaneous fibers were recorded in the median nerve of the deeply anesthetized rat and the receptor morphology in the forelimb glabrous skin was analyzed to...
Single cutaneous fibers were recorded in the median nerve of the deeply anesthetized rat and the receptor morphology in the forelimb glabrous skin was analyzed to establish a probable correlation between receptor anatomy and physiology. Receptor complexes in the glabrous skin of the rat forelimb were stained immunologically with antibodies NF-200 and PGP-9.5, confirming the presence of Meissner corpuscles and Merkel complexes within the dermal papilla similar to other mammals including primates. Both the Meissner corpuscles and Merkel cell complexes were sparse and located in the pyramidal-shaped palmer pads and the apex of the digit extremities. They were almost totally absent elsewhere in the glabrous skin. No Ruffini receptors or Pacinian corpuscles were found in our samples. A total of 92 cutaneous fibers were retained long enough for analysis. Thirty-five (38%) were characterized as rapidly adapting fibers (RA) and 57 (62%) were slowly adapting afferents (SA). Despite the very limited number of receptors at the tip of the digit, RA receptors outnumbered SA fibers 3.2/1.0. In contrast, SA fibers on the thenar pad outnumbered RA receptors by a ratio of 3-1. Despite the very limited number of low threshold mechanoreceptors in the glabrous skin of the rat forelimb, the prevalence of SA afferents in the palm and more frequent occurrence of RA afferents in the digit extremity suggest differences in functionality both for locomotion and object manipulation.
Topics: Animals; Forelimb; Hand; Mechanoreceptors; Median Nerve; Rats; Skin
PubMed: 34519842
DOI: 10.1007/s00221-021-06193-7