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Journal of Experimental Zoology. Part... May 2005Vargas and Fallon (2005. J Exp Zool (Mol Dev Evol) 304B:86-90) propose that Hox gene expression patterns indicate that the most anterior digit in bird wings is... (Comparative Study)
Comparative Study Review
Vargas and Fallon (2005. J Exp Zool (Mol Dev Evol) 304B:86-90) propose that Hox gene expression patterns indicate that the most anterior digit in bird wings is homologous to digit 1 rather than to digit 2 in other amniotes. This interpretation is based on the presence of Hoxd13 expression in combination with the absence of Hoxd12 expression in the second digit condensation from which this digit develops (the first condensation is transiently present). This is a pattern that is similar to that in the developing digit 1 of the chicken foot and the mouse hand and foot. They have tested this new hypothesis by analysing Hoxd12 and Hoxd13 expression patterns in two polydactylous chicken mutants, Silkie and talpid2. They conclude that the data support the notion that the most anterior remaining digit of the bird wing is homologous to digit 1 in other amniotes either in a standard phylogenetic sense, or alternatively in a (limited) developmental sense in agreement with the Frameshift Hypothesis of Wagner and Gautier (1999, i.e., that the developmental pathway is homologous to the one that leads to a digit 1 identity in other amniotes, although it occurs in the second instead of the first digit condensation). We argue that the Hoxd12 and Hoxd13 expression patterns found for these and other limb mutants do not allow distinguishing between the hypothesis of Vargas and Fallon (2005. J Exp Zool (Mol Dev Evol) 304B:86-90) and the alternative one, i.e., the most anterior digit in bird wings is homologous to digit 2 in other amniotes, in a phylogenetic or developmental sense. Therefore, at the moment the data on limb mutants does not present a challenge to the hypothesis, based on other developmental data (Holmgren, 1955. Acta Zool 36:243-328; Hinchliffe, 1984. In: Hecht M, Ostrom JH, Viohl G, Wellnhofer P, editors. The beginnings of birds. Eichstätt: Freunde des Jura-Museum. p 141-147; Burke and Feduccia, 1997. Science 278:666-668; Kundrát et al., 2002. J Exp Zool (Mol Dev Evol) 294B:151-159; Larsson and Wagner, 2002. J Exp Zool (Mol Dev Evol) 294B:146-151; Feduccia and Nowicki, 2002. Naturwissenschaften 89:391-393), that the digits of bird wings are homologous to digits 2,3,4 in amniotes. We recommend further testing of the hypothesis by comparing Hoxd expression patterns in different taxa.
Topics: Animals; Biological Evolution; Birds; Dinosaurs; Homeodomain Proteins; Models, Biological; Wings, Animal
PubMed: 15880773
DOI: 10.1002/jez.b.21042 -
Developmental Cell Sep 2022Hedgehog signaling has traditionally been considered to be a morphogen for digits. In this issue of Developmental Cell, Zhu et al. show that a brief exposure to Sonic...
Hedgehog signaling has traditionally been considered to be a morphogen for digits. In this issue of Developmental Cell, Zhu et al. show that a brief exposure to Sonic Hedgehog is sufficient for digit specification, and this finding suggests that it is not acting as a direct morphogen but rather as an initiator of this process.
Topics: Body Patterning; Dust; Gene Expression Regulation, Developmental; Hedgehog Proteins; Limb Buds
PubMed: 36099905
DOI: 10.1016/j.devcel.2022.08.007 -
Experimental Brain Research Apr 2011We explored how digit forces and indices of digit coordination depend on the history of getting to a particular set of task parameters during static prehension tasks....
We explored how digit forces and indices of digit coordination depend on the history of getting to a particular set of task parameters during static prehension tasks. The participants held in the right hand an instrumented handle with a light-weight container attached on top of the handle. At the beginning of each trial, the container could be empty, filled to the half with water (0.4 l), or filled to the top (0.8 l). The water was pumped in/out of the container at a constant, slow rate over 10 s. At the end of each trial, the participants always held a half-filled container that has just been filled (Empty-Half), emptied (Full-Half) or stayed half-filled throughout the trial (Half-Only). Indices of covariation (synergy indices) of elemental variables (forces and moments of force produced by individual digits) stabilizing such performance variables as total normal force, total tangential force, and total moment of force were computed at two levels of an assumed control hierarchy. At the upper level, the task is shared between the thumb and virtual finger (an imagined digit with the mechanical action equal to that of the four fingers), while at the lower level the action of the virtual finger is shared among the actual four fingers. Filling or emptying the container led to a drop in the safety margin (proportion of grip force over the slipping threshold) below the values observed in the Half-Only condition. Synergy indices at both levels of the hierarchy showed changes over the Full-Half and Empty-Half condition. These changes could be monotonic (typical of moment of force and normal force) or non-monotonic (typical of tangential force). For both normal and tangential forces, higher synergy indices at the higher level of the hierarchy corresponded to lower indices at the lower level. Significant differences in synergy indices across conditions were seen at the final steady state showing that digit coordination during steady holding an object is history dependent. The observations support an earlier hypothesis on a trade-off between synergies at the two levels of a hierarchy. They also suggest that, when a change in task parameters is expected, the neural strategy may involve producing less stable (easier to change) actions. The results suggest that synergy indices may be highly sensitive to changes in a task variable and that effects of such changes persist after the changes are over.
Topics: Adult; Analysis of Variance; Biomechanical Phenomena; Female; Hand; Hand Strength; Humans; Male; Psychomotor Performance
PubMed: 21331525
DOI: 10.1007/s00221-011-2590-6 -
Journal of the American Veterinary... Nov 2021To describe clinical findings, treatments, and outcomes for cattle with complete traumatic exungulation.
OBJECTIVE
To describe clinical findings, treatments, and outcomes for cattle with complete traumatic exungulation.
ANIMALS
10 bovines.
PROCEDURES
Record databases of 2 teaching hospitals were searched to identify cattle treated for traumatic exungulation between January 1993 and December 2018. Information about signalment, clinical signs and findings, treatment, and outcome was extracted from the records or obtained by telephone communication with the owner.
RESULTS
Records for 5 bulls, 4 heifers, and 1 cow with a median age of 2 years (range, 1 day to 10 years) and weight of 379.1 kg (range, 30 to 909.1 kg) were reviewed. Duration of clinical signs ranged from ≤ 24 hours to 3.5 days. Five of 7 animals had a lameness score > 3/5. Complete exungulation occurred in 6 medial digits (3 hind limbs and 3 forelimbs) and 5 lateral digits (1 hind limb and 4 forelimbs); 1 calf had complete exungulation of both digits of a forelimb. Treatments included bandaging (n = 9), antimicrobials (9), anti-inflammatories (8), hoof block application to the adjacent digit (7), regional anesthesia (6), cast application (4), curettage of the third phalanx (3), regional antimicrobial perfusion (1), and local application of antimicrobial-impregnated beads (1). All 7 cattle with long-term (≥ 9 months) information available returned to their intended function; 6 had no residual lameness, and 3 required regular corrective trimming of the affected digit.
CONCLUSIONS AND CLINICAL RELEVANCE
Results suggested the prognosis for long-term survival and return to intended function is fair to good for cattle with complete exungulation.
Topics: Animals; Anti-Bacterial Agents; Cattle; Cattle Diseases; Female; Forelimb; Gait; Hindlimb; Hoof and Claw; Lameness, Animal; Male
PubMed: 34757941
DOI: 10.2460/javma.21.06.0300 -
JASA Express Letters May 2024Bimodal stimulation, a cochlear implant (CI) in one ear and a hearing aid (HA) in the other, provides highly asymmetrical inputs. To understand how asymmetry affects...
Bimodal stimulation, a cochlear implant (CI) in one ear and a hearing aid (HA) in the other, provides highly asymmetrical inputs. To understand how asymmetry affects perception and memory, forward and backward digit spans were measured in nine bimodal listeners. Spans were unchanged from monotic to diotic presentation; there was an average two-digit decrease for dichotic presentation with some extreme cases of decreases to zero spans. Interaurally asymmetrical decreases were not predicted based on the device or better-functioning ear. Therefore, bimodal listeners can demonstrate a strong ear dominance, diminishing memory recall dichotically even when perception was intact monaurally.
Topics: Humans; Cochlear Implants; Middle Aged; Aged; Male; Female; Dichotic Listening Tests; Adult; Auditory Perception; Hearing Aids
PubMed: 38727569
DOI: 10.1121/10.0025977 -
NeuroImage Jan 2019The dominant model of number processing suggests the existence of a Number Form Area (NFA) in the inferior temporal gyrus (ITG) that supports the processing of Arabic...
The dominant model of number processing suggests the existence of a Number Form Area (NFA) in the inferior temporal gyrus (ITG) that supports the processing of Arabic digits as visual symbols of number. However, studies have produced inconsistent evidence for the presence and laterality of digit-specific ITG activity. Furthermore, whether any such activity relates to mathematical competence is unknown. This study investigated these two issues using functional magnetic resonance imaging. Thirty-two adults performed digit and letter detection tasks and reading and mathematics tests. During digit detection, participants determined whether digits were present in a string of letters (e.g., AH3NR versus AHTNR). During letter detection, participants determined whether letters were present in a string of digits (e.g., 93R78 versus 93478). Results showed four clusters in frontal, occipital, and temporal regions for digit detection, including a left ITG cluster. Five clusters in frontal, parietal, occipital, and temporal regions were associated with letter detection, including a left ITG cluster. Digit and letter-related ITG clusters were spatially distinct; however, a direct contrast of digit and letter processing did not reveal greater activity in the left ITG for digit detection. Whole brain correlations showed greater digit-related activity in the right ITG for participants with higher calculation skills, but there was no correlation between letter activity and calculation skills. Together, our results suggest functional localization, but not specialization, for digits in the left ITG and provide the first evidence of a relationship between calculation skills and digit processing in the right ITG.
Topics: Adolescent; Brain Mapping; Female; Functional Laterality; Humans; Magnetic Resonance Imaging; Male; Mathematical Concepts; Pattern Recognition, Visual; Temporal Lobe; Young Adult
PubMed: 30342974
DOI: 10.1016/j.neuroimage.2018.10.047 -
Royal Society Open Science Jan 2018We revisit digit reduction in the horse and propose that all five digits are partially present in the modern adult forelimb. Osteological descriptions of selected...
We revisit digit reduction in the horse and propose that all five digits are partially present in the modern adult forelimb. Osteological descriptions of selected tetradactyl, tridactyl and monodactyl equids demonstrate the evolution of the forelimb. Histological, osteological and palaeontological evidence suggest that the distal forelimb is more complex than traditionally conceived. The current understanding is that the horse distal forelimb consists of one complete digit (III) and two reduced splint metacarpals (II and IV). Metacarpals II and IV each exhibit a ventral ridge, which we suggest represents the undifferentiated digits I and V. These ridges are present in the tridactyl , but are absent in the tetradactyl The carpal articulations of the five metacarpals match those of pentadactyl taxa. Distally, the frog, a V-shaped structure on the ventral hoof represents digits II and IV, and the wings and hoof cartilages of the distal phalanx are digits I and V. We relate this revised interpretation of the forelimb to Laetoli footprints, and suggest the side impressions are created from the hooves of I and V, rather than from II and IV. We show shades of pentadactyly within the manus.
PubMed: 29410871
DOI: 10.1098/rsos.171782 -
Dementia & Neuropsychologia 2019The digit span test is widely used to assess attention and working memory. It is a portable, relatively culture-free and frequently used test. However, the cultural...
UNLABELLED
The digit span test is widely used to assess attention and working memory. It is a portable, relatively culture-free and frequently used test. However, the cultural validity of this test, particularly in the Indian older population, is not well established.
OBJECTIVE
This study explores the usefulness of the digit span test for Indian older adults with different levels of education.
METHODS
Two hundred and fifty-eight community-dwelling healthy normal older adults formed the sample of this study. All study participants were screened using a semi-structured interview schedule, the modified MINI Screen, the Indian version of the Mini-Mental State Examination, a measure of activities of daily living and the digit span test administered verbally.
RESULTS
The results indicated that participants with higher educational level performed significantly better than low-educated participants on the digit span test. Participants with low education often struggled with the digit span test and resorted to guessing the digits.
CONCLUSION
Our study clearly demonstrates that the digit span test can be useful for educated participants. However, its usefulness and ecological validity is questionable for those with low education and low literacy, warranting future research.
PubMed: 31073387
DOI: 10.1590/1980-57642018dn13-010013 -
Developmental Dynamics : An Official... May 2015The regrowth of amputated appendage extremities and the distal tips of digits represent models of tissue regeneration in multiple vertebrate taxa. In humans, digit tip... (Review)
Review
BACKGROUND
The regrowth of amputated appendage extremities and the distal tips of digits represent models of tissue regeneration in multiple vertebrate taxa. In humans, digit tip injuries, including traumatic amputation and crush injuries, are among the most common type of injury to the human hand. Despite clinical reports demonstrating natural regeneration of appendages in lower vertebrates and human digits, current treatment options are suboptimal, and are complicated by the anatomical complexities and functions of the different tissues within the digits.
RESULTS
In light of these challenges, we focus on recent advancements in understanding appendage regeneration from model organisms. We pay special attention to the cellular programs underlying appendage regeneration, where cumulative data from salamanders, fish, frogs, and mice indicate that regeneration occurs by the actions of lineage-restricted precursors. We focus on pathologic states and the interdependency that exists, in both humans and animal models, between the nail organ and the peripheral nerves for successful regeneration.
CONCLUSIONS
The increased understanding of regeneration in animal models may open new opportunities for basic and translational research aimed at understanding the mechanisms that support limb regeneration, as well as amelioration of limb abnormalities and pathologies.
Topics: Amputation, Traumatic; Animals; Finger Injuries; Humans; Mice; Regeneration
PubMed: 25715837
DOI: 10.1002/dvdy.24265