-
Proceedings. Biological Sciences Aug 2021Tetrapods use their neck to move the head three-dimensionally, relative to the body and limbs. Fish lack this anatomical neck, yet during feeding many species elevate...
Tetrapods use their neck to move the head three-dimensionally, relative to the body and limbs. Fish lack this anatomical neck, yet during feeding many species elevate (dorsally rotate) the head relative to the body. Cranial elevation is hypothesized to result from the craniovertebral and cranial-most intervertebral joints acting as a neck, by dorsally rotating (extending). However, this has never been tested due to the difficulty of visualizing and measuring vertebral motion . I used X-ray reconstruction of moving morphology to measure three-dimensional vertebral kinematics in rainbow trout () and Commerson's frogfish () during feeding. Despite dramatically different morphologies, in both species dorsoventral rotations extended far beyond the craniovertebral and cranial intervertebral joints. Trout combine small (most less than 3°) dorsal rotations over up to a third of their intervertebral joints to elevate the neurocranium. Frogfish use extremely large (often 20-30°) rotations of the craniovertebral and first intervertebral joint, but smaller rotations occurred across two-thirds of the vertebral column during cranial elevation. Unlike tetrapods, fish rotate large regions of the vertebral column to rotate the head. This suggests both cranial and more caudal vertebrae should be considered to understand how non-tetrapods control motion at the head-body interface.
Topics: Animals; Biomechanical Phenomena; Cervical Vertebrae; Joints; Motion; Radiography
PubMed: 34428973
DOI: 10.1098/rspb.2021.1091 -
Journal of Wrist Surgery Feb 2018Patients with scapholunate instability usually have pain in the dorsal wrist. This pain may occur due to the impingement between the scaphoid and the dorsal rim of...
Patients with scapholunate instability usually have pain in the dorsal wrist. This pain may occur due to the impingement between the scaphoid and the dorsal rim of the radius when the scaphoid is detached from the lunate. This pain appears as the scaphoid is displaced over the dorsal rim of the radius. The arthroscopic scaphoid 3D (dorsal, dynamic, displacement) test is described here to check this pathologic dorsal displacement of the scaphoid. The test should be performed both in the radiocarpal and midcarpal joints. Traction is released and the arthroscope is set under the lunate when tested in the radiocarpal joint and on the lunate when tested in the midcarpal joint. The scaphoid is manually pushed dorsally at the scaphoid tubercle. If there was no scapholunate instability, all the proximal row bones are minimally displaced: a negative test. If there was scapholunate instability, the scaphoid is displaced dorsally while the lunate remains static: evaluated as positive. This test can add information to the arthroscopic classifications of the scapholunate instability, which explore both the proximal to distal displacement of the scaphoid (the step-off) and the ulnar to radial displacement (the gap), as this test explores the volar to dorsal displacement.
PubMed: 29383283
DOI: 10.1055/s-0037-1601578 -
Journal of Evolutionary Biology Nov 2022Many organisms use conspicuous colour patterns to advertise their toxicity or unpalatability, a strategy known as aposematism. Despite the recognized benefits of this...
Many organisms use conspicuous colour patterns to advertise their toxicity or unpalatability, a strategy known as aposematism. Despite the recognized benefits of this anti-predator tactic, not all chemically defended species exhibit warning coloration. Here, we use a comparative approach to investigate which factors predict the evolution of conspicuousness in frogs, a group in which conspicuous coloration and toxicity have evolved multiple times. We extracted colour information from dorsal and ventral photos of 594 frog species for which chemical defence information was available. Our results show that chemically defended and diurnal species have higher internal chromatic contrast, both ventrally and dorsally, than chemically undefended and/or nocturnal species. Among species that are chemically defended, conspicuous coloration is more likely to occur if species are diurnal. Our results also suggest that the evolution of conspicuous colour is more likely to occur in chemically defended prey with smaller body size. We discuss potential explanations for this association and suggest that prey profitability (related to body size) could be an important force driving the macroevolution of warning signals.
Topics: Animals; Biological Evolution; Anura; Biological Mimicry
PubMed: 36129907
DOI: 10.1111/jeb.14092 -
Scientific Reports Oct 2023Irrespective of the exceptional adaptation of dromedaries to harsh environmental conditions, they remain highly susceptible to joint lameness resulting from a range of...
Irrespective of the exceptional adaptation of dromedaries to harsh environmental conditions, they remain highly susceptible to joint lameness resulting from a range of diverse factors and conditions. The joints most often affected by traumatic osteoarthritis in dromedaries are the metacarpophalangeal and metatarsophalangeal joints. A comprehensive understanding of joint anatomy and topography of the dromedary is required to perform arthrocentesis correctly on affected joints. Forty-two distal limbs were taken from 28 camels and studied by gross dissection, casting, ultrasonography, and computed tomography (CT). Representative three-dimensional models of the joint cavities, recesses, and pouches were obtained using different casting agents. This study provides a detailed description of dorsally, axially, and abaxially positioned joint recesses, as well as palmar/plantar positioned joint pouches. The safety and feasibility of the different arthrocentesis approaches were evaluated. The traditional dorsal arthrocentesis approach of the metacarpophalangeal, metatarsophalangeal, proximal interphalangeal, and distal interphalangeal joints, has limitations due to the risk of damaging the tendon structures and articular cartilage, which can lead to joint degeneration. A lateral arthrocentesis approach via the proximal palmar/plantar pouches of the metacarpophalangeal/metatarsophalangeal and proximal interphalangeal joints is recommended. This approach eliminates the potential needle injury to the articulating joint cartilage and other surrounding joint structures, such as tendons, blood vessels, and nerves.
Topics: Animals; Camelus; Arthrocentesis; Forelimb; Joints; Cartilage, Articular; Metatarsophalangeal Joint
PubMed: 37833397
DOI: 10.1038/s41598-023-44391-1 -
WIREs Mechanisms of Disease Sep 2021The spinal cord is functionally and anatomically divided into ventrally derived motor circuits and dorsally derived somatosensory circuits. Sensory stimuli originating... (Review)
Review
The spinal cord is functionally and anatomically divided into ventrally derived motor circuits and dorsally derived somatosensory circuits. Sensory stimuli originating either at the periphery of the body, or internally, are relayed to the dorsal spinal cord where they are processed by distinct classes of sensory dorsal interneurons (dIs). dIs convey sensory information, such as pain, heat or itch, either to the brain, and/or to the motor circuits to initiate the appropriate response. They also regulate the intensity of sensory information and are the major target for the opioid analgesics. While the developmental mechanisms directing ventral and dorsal cell fates have been hypothesized to be similar, more recent research has suggested that dI fates are specified by novel mechanisms. In this review, we will discuss the molecular events that specify dorsal neuronal patterning in the spinal cord, thereby generating diverse dI identities. We will then discuss how this molecular understanding has led to the development of robust stem cell methods to derive multiple spinal cell types, including the dIs, and the implication of these studies for treating spinal cord injuries and neurodegenerative diseases. This article is categorized under: Neurological Diseases > Stem Cells and Development.
Topics: Cell Differentiation; Interneurons; Neurons; Spinal Cord; Touch
PubMed: 34730293
DOI: 10.1002/wsbm.1520 -
Experimental Brain Research Jul 2021The two-visual stream hypothesis posits that the dorsal stream is less susceptible than the ventral stream to the effects of illusions and visual priming. While previous...
The two-visual stream hypothesis posits that the dorsal stream is less susceptible than the ventral stream to the effects of illusions and visual priming. While previous studies have separately examined these perceptual manipulations, the present study combined the effects of a visual illusion and priming to examine the possibility of dorsally guided actions being susceptible to the perceptual stimuli due to interactions between the two streams. Thirty-four participants were primed with a 'long' or 'short' version of the Sander Parallelogram illusion and were asked to either reach out and grasp or manually estimate the length of a rod placed on a version of the illusion that was on some trials the same as the prime (congruent) and on other trials was the inverse (incongruent). Due to the context-focused nature of ventral processing, we predicted that estimations would be more susceptible to the effects of the illusion and priming than grasps. Results showed that while participants' manual estimations were susceptible to both priming and the illusion, the grasps were only affected by the illusion, not by priming. The influence of the illusion on grip aperture was greater during manual estimations than it was during grasping. These findings support the notion that the functionally distinct dorsal and ventral streams interact under the current experimental paradigm. Outcomes of the study help better understand the nature of stimuli that promote interactions between the dorsal and ventral streams.
Topics: Hand Strength; Humans; Illusions; Motor Activity; Psychomotor Performance; Visual Perception
PubMed: 34013396
DOI: 10.1007/s00221-021-06076-x -
Developmental Biology Jul 2018Amphibian embryos provide a powerful system to study early cell fate determination because their eggs are externally fertilised, large, and easy to manipulate....
Amphibian embryos provide a powerful system to study early cell fate determination because their eggs are externally fertilised, large, and easy to manipulate. Ultraviolet (UV) or lithium chloride (LiCl) treatment are classic embryonic manipulations frequently used to perturb specification of the dorso-ventral (DV) axis by affecting the stability of the maternal Wnt mediator β-catenin. Such treatments result in the formation of so-called ventralised or dorsalised embryos. Although these phenotypes have been well described with respect to their morphology and some aspects of gene expression, their whole transcriptomes have never been systematically characterised and compared. Here we show that at the early gastrula stage UV-treated embryos are transcriptionally more closely related to untreated embryos than to LiCl-treated embryos. Transcriptional comparisons with dissected ventral and dorsal regions of unperturbed gastrula embryos indicate that UV and LiCl treatments indeed enrich for ventral and dorsal cells, respectively. However, these treatments also affect the balance of neural induction in the ectodermal germ layer, with LiCl stimulating pro-neural BMP inhibition and UV preferentially generating epidermis because of elevated BMP levels. Thus the transcriptomes of UV- and LiCl-treated embryos can best be described as ventro-epidermalised and dorso-neuralised. These descriptions notwithstanding, our profiling reveals several hitherto uncharacterized genes with differential expression along the DV axis. At least one of these genes, a RNF220-like ubiquitin ligase, is activated dorsally by β-catenin. Our analysis of UV/LiCl-mediated axis perturbation will enhance the mechanistic understanding of DV axis determination in vertebrates.
Topics: Animals; Body Patterning; Gastrula; Gastrulation; Gene Expression Profiling; Gene Expression Regulation, Developmental; Germ Layers; Lithium Chloride; Signal Transduction; Transcriptome; Ultraviolet Rays; Wnt Proteins; Xenopus; Xenopus Proteins
PubMed: 29709598
DOI: 10.1016/j.ydbio.2018.04.022 -
Scientific Reports Dec 2020Visual perception of actions and objects has been shown to activate different cortical systems: action perception system spanning more dorsally, across parietal,...
Visual perception of actions and objects has been shown to activate different cortical systems: action perception system spanning more dorsally, across parietal, frontal, and dorsal temporal regions; object perception relying more strongly the ventral occipitotemporal cortex (VOTC). Compared to the well-established object-domain structure (e.g., faces vs. artifacts) in VOTC, it is less known whether the action perception system is constrained by similar domain principle and whether it communicates with the ventral object recognition system in a domain-specific manner. In a fMRI long-block experiment designed to evaluate both regional activity and task-based functional connectivity (FC) patterns, participants viewed animated videos of a human performing two domains of actions to the same set of meaningless shapes without object-domain information: social-communicative-actions (e.g., waving) and manipulation-actions (e.g., folding). We observed action-domain-specific activations, with the superior temporal sulcus and the right precentral region responding more strongly during social-communicative-action perception; the supramarginal gyrus, inferior and superior parietal lobe, and precentral gyrus during manipulation-action perception. The two domains of action perception systems communicated with VOTC in domain-specific manners: FC between the social-communicative-action system and the bilateral fusiform face area was enhanced during social-communicative-action perception; FC between the manipulation-action system and the left tool-preferring lateral occipitoptemporal cortex was enhanced during manipulation-action perception. There was a significant correlation between the FC-with-action-system and the local activity strength across VOTC voxels. Our findings highlight social- and manipulation-domains of human interaction as an overarching principle of both object and action perception systems, with domain-based functional communication across systems.
Topics: Adolescent; Adult; Brain; Brain Mapping; Female; Humans; Magnetic Resonance Imaging; Male; Psychomotor Performance; Visual Perception; Young Adult
PubMed: 33273681
DOI: 10.1038/s41598-020-78276-4 -
Journal of Orthopaedic Surgery and... Apr 2023Bone functional adaptation rationalises the inhomogeneous morphology found in bone. By means of computed tomography osteoabsorptiometry and micro-computed tomography,...
BACKGROUND
Bone functional adaptation rationalises the inhomogeneous morphology found in bone. By means of computed tomography osteoabsorptiometry and micro-computed tomography, the mineralisation of the subchondral endplates and trabecular microstructure of vertebral bodies can be assessed to visualise the chronic loading conditions bone endures over time. In this study, we determined cancellous and compartment-specific trabecular architecture in the cervical vertebra to aid with successful integration of orthopaedic implants.
METHODS
We examined the micro-computed tomography scans of seven prospectively healthy C4 vertebrae, evaluated their microstructure parameters (bone volume fraction (BV/TV), bone surface density (BS/BV), trabecular thickness (Tb.Th), trabecular separation (Tb.Sp), trabecular number per volume (Tb.N), connectivity density (Conn.D), structure model index (SMI), and degree of anisotropy (DA), and compared the trabecular architecture in twelve predefined volumes of interest: the cranial and caudal 0-10%, 10-15%, and 25-50% in both the ventral and dorsal half. Using computed tomography osteoabsorptiometry, the subchondral bone mineralisation of the subchondral endplates of nine C4 vertebrae was also evaluated.
RESULTS
Highest mineralisation is located dorsally at the endplates. Tb.Sp and Tb.N were the only two parameters that displayed significant differences in averaged values of VOI. Nonetheless, distinct, consistent ventral-dorsal modulations were seen in matched sample ventral-dorsal comparison in the BV/TV, BS/BV, and SMI overall levels, as well as in Tb.Th in the three caudal levels. To simplify, the vertebra was split into ventral-cranial, dorsal-cranial, ventral-caudal, and dorsal-caudal equal quarters. The ventral quarters display lower BV/TV, respectively, higher BS/BV and SMI than their sample paired dorsal quarters. The ventral-cranial quarter shows the lowest BV/TV and the highest BS/BV and SMI, describing spacious cancellous bone with rod-like trabeculae. In contrast, the dorsal-caudal quarter exhibits the highest BV/TV and Tb.Th and the lowest BS/BV and SMI, illustrating thicker, denser, and more plate-like trabeculae. The dorsal-cranial and ventral-caudal quarters are comparable and represent intermediate characteristics.
CONCLUSIONS
CT-OAM and µCT demonstrate the interdependence of compact and trabecular bone in response to long-term loading conditions. Results show highest mineralisation in the dorso-caudal part of the C4 vertebra. Recommended placement of orthopaedic implants should be positioned dorsally with screws anchored in the dorsal-caudal region.
Topics: X-Ray Microtomography; Bone Density; Skull; Calcification, Physiologic; Cervical Vertebrae
PubMed: 37046305
DOI: 10.1186/s13018-023-03760-2 -
Anatomical Science International Jan 2016The lateral atlantoaxial joints contain folds of synovium termed meniscoids that may potentially contribute to cervical spine pain; however, the anatomy of these...
The lateral atlantoaxial joints contain folds of synovium termed meniscoids that may potentially contribute to cervical spine pain; however, the anatomy of these structures has not been comprehensively investigated. The purpose of this study was to explore the morphology and morphometry of lateral atlantoaxial joint meniscoids. Twelve cadaveric hemi-spines (6 female; 6 left; mean 81.5 years, SD 7.3) were obtained for dissection and disarticulation of the lateral atlantoaxial joints. Meniscoids were identified and measurements made of surface area, length, and surrounding articular cartilage degeneration. Tissue was sectioned sagittally, stained with hematoxylin and eosin, and examined by light microscopy. Data were analyzed descriptively and using nonparametric techniques. Ventral and dorsal meniscoids (24 in total) were found in each joint, and could be classified histologically into adipose (32%), fibrous (41%), and fibroadipose (27%) meniscoids. No significant associations were found between meniscoid size and age, histology, cartilage degeneration, or joint position. Meniscoid length in males was significantly greater than in females (P = 0.04). Fibrous meniscoids were noted to be associated with articular cartilage degeneration, and adipose and fibroadipose meniscoids with intact cartilage (P = 0.05). Fibrous meniscoids tended to be located dorsally (78%), whereas adipose meniscoids were mostly located ventrally (86%). Distinct patterns in lateral atlantoaxial joint meniscoid morphology were observed, including the association of fibrous meniscoid composition with dorsal joint position and articular cartilage degeneration. The clinical significance of these patterns remains uncertain, and further research is needed to examine these structures across the lifespan and in cervical pathology.
Topics: Aged; Aged, 80 and over; Atlanto-Axial Joint; Cadaver; Cervical Vertebrae; Female; Humans; Male; Pain; Sex Characteristics; Synovial Membrane
PubMed: 25680920
DOI: 10.1007/s12565-015-0276-z