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Scientific Reports Nov 2023Spatial acuity is a fundamental property of any sensory system. In the case of the somatosensory system, the two-point discrimination (2PD) test has long been used to...
Spatial acuity is a fundamental property of any sensory system. In the case of the somatosensory system, the two-point discrimination (2PD) test has long been used to investigate tactile spatial resolution. However, the somatosensory system comprises three main mechanoreceptive channels: the slowly adapting channel (SA) responds to steady pressure, the rapidly adapting channel (RA) responds to low-frequency vibration, and the Pacinian channel (PC) responds to high-frequency vibration. The use of mechanical stimuli in the classical 2PD test means that previous studies on tactile acuity have primarily focussed on the pressure-sensitive channel alone, while neglecting other submodalities. Here, we used a novel ultrasound stimulation to systematically investigate the spatial resolution of the two main vibrotactile channels. Contrary to the textbook view of poor spatial resolution for PC-like stimuli, across four experiments we found that high-frequency vibration produced surprisingly good spatial acuity. This effect remained after controlling for interchannel differences in stimulus detectability and perceived intensity. Laser doppler vibrometry experiments confirmed that the acuity of the PC channel was not simply an artifact of the skin's resonance to high-frequency mechanical stimulation. Thus, PC receptors may transmit substantial spatial information, despite their sparse distribution, deep location, and large receptive fields.
Topics: Touch; Mechanoreceptors; Pacinian Corpuscles; Afferent Pathways; Vibration
PubMed: 38036579
DOI: 10.1038/s41598-023-48037-0 -
Diagnostics (Basel, Switzerland) Jun 2024The emergence of 7T clinical MRI technology has sparked our interest in its ability to discern the complex structures of the hand. Our primary objective was to assess...
The emergence of 7T clinical MRI technology has sparked our interest in its ability to discern the complex structures of the hand. Our primary objective was to assess the sensory and motor nerve structures of the hand, specifically nerves and Pacinian corpuscles, with the dual purpose of aiding diagnostic endeavors and supporting reconstructive surgical procedures. Ethical approval was obtained to carry out 7T MRI scans on a cohort of volunteers. Four volunteers assumed a prone position, with their hands ( = 8) positioned in a "superman" posture. To immobilize and maintain the hand in a strictly horizontal position, it was affixed to a plastic plate. Passive B0 shimming was implemented. Once high-resolution 3D images had been acquired using a multi-transmit head coil, advanced post-processing techniques were used to meticulously delineate the nerve fiber networks and mechanoreceptors. Across all participants, digital nerves were consistently located on the phalanges area, on average, between 2.5 and 3.5 mm beneath the skin, except within flexion folds where the nerve was approximately 1.8 mm from the surface. On the phalanges area, the mean distance from digital nerves to joints was approximately 1.5 mm. The nerves of the fingers were closer to the bone than to the surface of the skin. Furthermore, Pacinian corpuscles exhibited a notable clustering primarily within the metacarpal zone, situated on the palmar aspect. Our study yielded promising results, successfully reconstructing and meticulously describing the anatomy of nerve fibers spanning from the carpus to the digital nerve division, alongside the identification of Pacinian corpuscles, in four healthy volunteers (eight hands).
PubMed: 38928648
DOI: 10.3390/diagnostics14121230 -
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 -
Annals of Anatomy = Anatomischer... Feb 2024Afferent innervation of shoulder joints plays a fundamental role in nociception and mechanoception and its alteration result in shoulder´s disease that course with pain...
BACKGROUND
Afferent innervation of shoulder joints plays a fundamental role in nociception and mechanoception and its alteration result in shoulder´s disease that course with pain and functional disability.
METHODS
Joints shoulder from healthy subjects (n = 20) and with chronic pain shoulder syndromes (n = 17) were analyzed using immunohistochemistry for S100 protein to identify nerve structures (nerve fibers and sensory corpuscles), coupled with a quantification of the sensory formations. Sensory nerve formations were quantified in 13 distinct areas in healthy joint shoulder and in the available equivalent areas in the pathological joints. Statistical analyses were conducted to assess differences between healthy shoulder and pathological shoulder joint (p< 0.05).
RESULTS
All analyzed structures, i.e., glenohumeral capsule, acromioclavicular capsule, the extraarticular structures (subcoracoid region and subacromio-subdeltoid bursa) and intraarticular structures (biceps brachii tendon and labrum articulare) are variably innervated except the extrinsic coracoacromial ligament, which was aneural. The afferent innervation of healthy human shoulder joints consists of free nerve endings, simple lamellar corpuscles and Ruffini's corpuscles. Occasionally, Golgi-Mazzoni's and Pacinian corpuscles were found. However, the relative density of each one varied among joints and/or the different zones within the same joint. As a rule, the upper half and anterior half of healthy glenohumeral capsules have a higher innervation compared to the lower and posterior respectably. On the other hand, in joints from subjects suffering chronic shoulder pain, a reduced innervation was found, involving more the corpuscles than free nerve endings.
CONCLUSIONS
Our findings report a global innervation map of the human shoulder joints, especially the glenohumeral one, and this knowledge might be of interest for arthroscopic surgeons allowing to develop more selective and unhurt treatments, controlling the pain, and avoiding the loss of afferent innervation after surgical procedures. To the light of our results the postero-inferior glenohumeral capsular region seems to be the more adequate to be a surgical portal (surgical access area) to prevent nerve lesions.
Topics: Humans; Shoulder Joint; Shoulder; Chronic Pain; Mechanoreceptors; Sensory Receptor Cells
PubMed: 38154784
DOI: 10.1016/j.aanat.2023.152206 -
Annals of Anatomy = Anatomischer... Feb 2024The cutaneous end organ complexes or cutaneous sensory corpuscles are specialized sensory organs associated to low-threshold mechanoreceptors. Mechano-gated proteins...
BACKGROUND
The cutaneous end organ complexes or cutaneous sensory corpuscles are specialized sensory organs associated to low-threshold mechanoreceptors. Mechano-gated proteins forming a part of ion channels have been detected in both the axon and terminal glial cells of Meissner corpuscles, a specific cutaneous end organ complex in the human glabrous skin. The main candidates to mechanotransduction in Meissner corpuscles are members of the Piezo family of cationic ion channels. PIEZO2 has been detected in the axon of these sensory structures whereas no data exists about the occurrence and cell localization of PIEZO1.
METHODS
Skin samples (n = 18) from the palmar aspect of the distal phalanx of the first and second fingers were analysed (8 female and 10 males; age range 26 to 61 26-61 years). Double immunofluorescence for PIEZO1 and PIEZO2 together with axonal or terminal glial cell markers was captured by laser confocal microscopy, and the percentage of PIEZOs positive Meissner corpuscles was evaluated.
RESULTS
MCs from human fingers showed variable morphology and degree of lobulation. Regarding the basic immunohistochemical profile, in all cases the axons were immunoreactive for neurofilament proteins, neuron specific enolase and synaptophysin, while the lamellar cells displayed strong S100P immunoreactivity. PIEZO1 was detected co-localizing with axonal markers, but never with terminal glial cell markers, in the 56% of Meissner corpuscles; weak but specific immunofluorescence was additionally detected in the epidermis, especially in basal keratinocytes. Similarly, PIEZO2 immunoreactivity was found restricted to the axon in the 85% of Meissner corpuscles. PIEZO2 positive Merkel cells were also regularly found.
CONCLUSIONS
PIEZO1 and PIEZO2 are expressed exclusively in the axon of a subpopulation of human digital Meissner corpuscles, thus suggesting that not only PIEZO2, but also PIEZO1 may be involved in the mechanotransduction from low-threshold mechanoreceptors.
Topics: Female; Humans; Male; Ion Channels; Mechanoreceptors; Mechanotransduction, Cellular; Merkel Cells; Pacinian Corpuscles; Skin; Adult; Middle Aged
PubMed: 38109982
DOI: 10.1016/j.aanat.2023.152200 -
Somatosensory & Motor Research Mar 2024The purpose of this study was to determine the changes in the Blood Oxygen Level Dependent signal of Primary somatosensory area (S1) and Brodmann area 3 (BA3) per finger...
PURPOSE AND METHOD
The purpose of this study was to determine the changes in the Blood Oxygen Level Dependent signal of Primary somatosensory area (S1) and Brodmann area 3 (BA3) per finger and phalanx in comparison to the activation voxel when 250 Hz vibratory stimulation with high sensitivity for the Pacinian corpuscle was given to the four fingers and three phalanges.
RESULTS
The result of analyzing the activation voxel showed a significant difference for S1 per finger and phalanx, but for BA3, no significant difference was observed despite a similar trend to S1. In contrast, the activation intensity (BOLD) displayed a significant difference for S1 per finger and phalanx and for BA3, where the activation voxel had no significant variation. In addition, while the result of S1 did not indicate whether the index or the little fingers had the highest sensitivity based on the BOLD signal per finger, the result of BA3 marked the strongest BOLD signal for the little finger as a response to 250 Hz vibratory stimulation. The activation intensity per phalanx was the highest for the intermediate phalanx for S1 and BA3, which was in line with a previous study comparing the activation voxel.
CONCLUSIONS
The method based on the intensity of the nerve activation is presumed to have high sensitivity as the signal intensity is monitored within a specific, defined area. Thus, for the extraction of brain activation patterns of micro-domains, such as BA3, monitoring the BOLD signal that reflects the nerve activation intensity more sensitively is likely to be advantageous.
Topics: Somatosensory Cortex; Magnetic Resonance Imaging; Fingers; Brain Mapping
PubMed: 36721377
DOI: 10.1080/08990220.2023.2173165 -
Pathology International Jan 2024
The enigmatic occurrence of Pacinian corpuscles in the prostate gland: Report of a case with pericorpuscular and intracorpuscular growth of prostatic acinar adenocarcinoma.
Topics: Male; Humans; Pacinian Corpuscles; Prostate; Prostatic Neoplasms; Carcinoma, Acinar Cell
PubMed: 38050798
DOI: 10.1111/pin.13392