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Theresa A Jones - One of the best experts on this subject based on the ideXlab platform.

  • Training the "less-affected" Forelimb after unilateral cortical infarcts interferes with functional recovery of the impaired Forelimb in rats.
    Restorative Neurology and Neuroscience, 2020
    Co-Authors: Rachel P Allred, Monica A. Maldonado, Theresa A Jones

    Purpose: Unilateral lesions of the sensorimotor cortex (SMC) in adult rats cause major behavioral changes in the ipsilesional, "less-affected" Forelimb. An increase in function and reliance on this Forelimb can aid compensation for contralesional impairments, but may also promote disuse and reduced functionality of the impaired Forelimb. We hypothesized that training focused on the ipsilesional Forelimb following a unilateral SMC lesion would reduce the efficacy of later motor rehabilitative training of the impaired Forelimb. Methods: Rats with ischemic SMC lesions were trained on a skilled reaching task with the ipsilesional Forelimb (PriorT) or received control procedures (Cont) for 10 days. Both groups were then trained with the impaired Forelimb on the same reaching task for 10 days. Results: In comparison with Cont, PriorT rats had little improvement on the reaching task with the impaired Forelimb and had a more enduring disuse of the impaired Forelimb for postural support behaviors. Lesion sizes were similar between groups. Conclusions: Behavioral experience with the less-affected Forelimb early after unilateral SMC lesions has the potential to increase disuse and dysfunction of the impaired Forelimb, consistent with a training-induced exacerbation of learned non-use. These findings are suggestive of competitive processes in experience-dependent neural restructuring after brain damage.

  • the organization of the Forelimb representation of the c57bl 6 mouse motor cortex as defined by intracortical microstimulation and cytoarchitecture
    Cerebral Cortex, 2011
    Co-Authors: Kelly A Tennant, Deanna L Adkins, Nicole A Donlan, Aaron L Asay, Nagheme Thomas, Jeffrey A Kleim, Theresa A Jones

    The organization of Forelimb representation areas of the monkey, cat, and rat motor cortices has been studied in depth, but its characterization in the mouse lags far behind. We used intracortical microstimulation (ICMS) and cytoarchitectonics to characterize the general organization of the C57BL/6 mouse motor cortex, and the Forelimb representation in more detail. We found that the Forelimb region spans a large area of frontal cortex, bordered primarily by vibrissa, neck, shoulder, and hindlimb representations. It included a large caudal Forelimb area, dominated by digit representation, and a small rostral Forelimb area, containing elbow and wrist representations. When the entire motor cortex was mapped, the Forelimb was found to be the largest movement representation, followed by head and hindlimb representations. The ICMS-defined motor cortex spanned cytoarchitecturally identified lateral agranular cortex (AGl) and also extended into medial agranular cortex. Forelimb and hindlimb representations extended into granular cortex in a region that also had cytoarchitectural characteristics of AGl, consistent with the primary motor–somatosensory overlap zone (OL) characterized in rats. Thus, the mouse motor cortex has homologies with the rat in having 2 Forelimb representations and an OL but is distinct in the predominance of digit representations.

  • maladaptive effects of learning with the less affected Forelimb after focal cortical infarcts in rats
    Experimental Neurology, 2008
    Co-Authors: Rachel P Allred, Theresa A Jones

    It is common following stroke to focus early rehabilitation efforts on developing compensatory use of the less-affected body side. Here we used a rat model of focal cortical infarct to examine how motor skill acquisition with the less-affected (“intact”) Forelimb influences sensorimotor function of the infarct-impaired Forelimb and neural activity in peri-infarct cortex. Rats proficient in skilled reaching with one Forelimb were given focal ischemic lesions in the contralateral sensorimotor cortex (SMC). Recovery in this Forelimb was tested following a period of reach training focused on the intact Forelimb or control procedures. Quantitative measures of the cumulatively expressed transcription factor, FosB/ΔFosB, were used to assay intact Forelimb training effects on neuronal activity in remaining SMC of the infarcted hemisphere. Intact Forelimb training worsened behavioral recovery in the impaired Forelimb following unilateral focal ischemia. Furthermore, it decreased neuronal FosB/ΔFosB expression in layer II/III of peri-infarct SMC. These effects were not found in sham-operated rats trained sequentially with both Forelimbs or in animals receiving bilateral Forelimb training after unilateral infarcts. Thus, focused use of the intact Forelimb has detrimental effects on recovery of impaired Forelimb function following a focal ischemic injury and this is linked to reduced neuronal activation in remaining cortex. These results suggest that peri-infarct cortex becomes vulnerable to early post-stroke experience with the less-affected Forelimb and that this experience may drive neural plasticity here in a direction that is maladaptive for functional outcome.

Jinhua Chen - One of the best experts on this subject based on the ideXlab platform.

  • Sensing platform for acoustic startle responses from rat Forelimbs and hindlimbs
    IEEE Transactions on Biomedical Engineering, 1996
    Co-Authors: R.l. Seaman, Jinhua Chen

    A sensing platform with two piezoelectric transducers was designed and fabricated to measure acoustic startle responses from Forelimbs and hindlimbs in the fat. Testing with a vibrator showed that separate forces were measured from 5 to 25 Hz with mean sensitivities of 2.395 and 2.022 V/N and mean linearity errors of 3.23 and 2.98% FS for the Forelimb and hindlimb sensors, respectively. Forelimb and hindlimb response waveforms of male Sprague-Dawley rats had shapes similar to the commonly recorded whole-body response but were smaller in amplitude.

  • Apparatus to detect limb components of startle in rat
    1992 14th Annual International Conference of the IEEE Engineering in Medicine and Biology Society, 1992
    Co-Authors: Jinhua Chen, Charles R. Watson, Ronald L. Seaman

    An apparatus to detect Forelimb, hindlimb, and whole-body rat acoustic startle responses was constructed and tested. The apparatus included separate sensors for Forelimbs and hindlimbs and a jointed animal holder. Limb responses were reasonably well isolated, allowing initial determination of their contributions to the whole-body response.

Pascal Dolle - One of the best experts on this subject based on the ideXlab platform.

  • embryonic retinoic acid synthesis is required for Forelimb growth and anteroposterior patterning in the mouse
    Development, 2002
    Co-Authors: Karen Niederreither, Julien Vermot, Brigitte Schuhbaur, Pierre Chambon, Pascal Dolle

    Numerous studies, often performed on avian embryos, have implicated retinoic acid (RA) in the control of limb bud growth and patterning. Here we have investigated whether the lack of endogenous RA synthesis affects limb morphogenesis in mutant mouse embryos deficient for the retinaldehyde dehydrogenase 2 (Raldh2/Aldh1a2). These mutants, which have no detectable embryonic RA except in the developing retina, die at E9.5-E10 without any evidence of limb bud formation, but maternal RA supplementation through oral gavage from E7.5 can extend their survival. Such survivors exhibit highly reduced Forelimb rudiments, but apparently normal hindlimbs. By providing RA within maternal food, we found both a stage- and dose-dependency for rescue of Forelimb growth and patterning. Following RA supplementation from E7.5 to 8.5, mutant Forelimbs are markedly hypoplastic and lack anteroposterior (AP) patterning, with a single medial cartilage and 1-2 digit rudiments. RA provided until E9.5 significantly rescues Forelimb growth, but cannot restore normal AP patterning. Increasing the RA dose rescues the hypodactyly, but leads to lack of asymmetry of the digit pattern, with abnormally long first digit or symmetrical polydactyly. Mutant Forelimb buds are characterized by lack of expression or abnormal distal distribution of Sonic hedgehog ( Shh ) transcripts, sometimes with highest expression anteriorly. Downregulation or ectopic anterior expression of Fgf4 is also seen. As a result, genes such as Bmp2 or Hoxd genes are expressed symmetrically along the AP axis of the Forelimb buds, and/or later, of the autopod. We suggest that RA signaling cooperates with a posteriorly restricted factor such as dHand, to generate a functional zone of polarizing activity (ZPA).

  • functional cooperation between the non paralogous genes hoxa 10 and hoxd 11 in the developing Forelimb and axial skeleton
    Development, 1996
    Co-Authors: Bertrand Favier, Pierre Chambon, Filippo M Rijli, Catherine Fromentalramain, Valerie Fraulob, Pascal Dolle

    The Abdominal B-related Hoxa-10 gene displays similar expression patterns in the differentiating Forelimbs and hindlimbs of the mouse, with preferential expression around the humeral and femoral cartilages and more diffuse expression in distal regions. We found that a targeted disruption of Hoxa-10 has almost no effect in the Forelimbs, while it affects the proximal hindlimb skeleton. The alterations were located along the dorsolateral side of the femur (labium laterale), with an enlargement and distal shift of the third trochanter, a misshapen lateral knee sesamoid, a supernumerary ‘ligament’ connecting these structures and an occasional duplication of the femoral trochlea. Some Hoxa-10−/− mutant mice developed severe degenerative alterations of the knee articulation upon ageing. Viable Hoxa-10/Hoxd-11 double mutant mice were produced by genetic intercrosses. The compound mutation resulted in synergistic Forelimb phenotypic alterations, consisting of: (i) an exacerbation of Hoxd-11−/− phenotypic traits in the carpal and digital region, e.g. more pronounced truncations of the ulna styloid, pyramidal and pisiform bones and of some metacarpal and phalangeal bones and (ii) marked alterations in a more proximal region which is nearly unaffected in Hoxd-11−/− single mutants; the entire radius and ulna were truncated and thickened, with deformations of the ulna proximal extremity. Thus, functional redundancy can occur even between non-paralogous Abdominal B-related Hox genes. The double Hoxa-10/Hoxd-11 mutation also conferred full penetrance to the sacral and caudal vertebrae transformations which are approximately 50% penetrant in Hoxd-11−/− single mutants, revealing that functional cooperation can also occur between non-paralogous Hox gene products in axial skeleton patterning.

Virginia Abdala - One of the best experts on this subject based on the ideXlab platform.

  • Functional Indices and Postnatal Ontogeny of Long Bones of the Forelimb in the Sigmodontine Rodents (Rodentia: Cricetidae)
    Journal of Mammalian Evolution, 2020
    Co-Authors: Luz Valeria Carrizo, María José Tulli, Virginia Abdala

    The adaptations for a particular locomotor type (e.g., fossorial or saltatorial) could affect limb bone morphology throughout ontogeny. We explore how the measurements of the Forelimbs and functional indices change along the postnatal ontogeny of 92 specimens of sigmodontines belonging to four genera ( Akodon , Eligmodontia , Oligoryzomys , and Oxymycterus ) with different locomotor types (ambulatory, quadrupedal-saltatorial, scansorial, and semifossorial). We examined individuals of different age categories: juveniles, young adults, and adults. Eleven linear measurements of long bones (humerus, radius, and ulna) corresponding to functional diameters and lengths were taken and analyzed through simple regressions (RMA) using geometric mean transformations. Six morphofunctional indices were then calculated and analyzed through multivariate analysis (MANOVA). The allometric patterns and morphofunctional indices show that the Forelimb tends to be elongated and slender in the ambulatory, scansorial, and quadrupedal-saltatorial species, and short and thicker in the semifossorial species. Morphofunctional indices do not separate our sample concerning age categories, possibly indicating that the juveniles of different rodent species are born with similar morphology to the adults in terms of locomotion.

  • new puzzling insights from comparative myological studies on the old and unsolved Forelimb hindlimb enigma
    Biological Reviews, 2013
    Co-Authors: Rui Diogo, Marta Lindemedina, Virginia Abdala, Miriam A Ashleyross

    Most textbooks and research reports state that the structures of the tetrapod Forelimbs and hindlimbs are serial homologues. From this view, the main challenge of evolutionary biologists is not to explain the similarity between tetrapod limbs, but instead to explain why and how they have diverged. However, these statements seem to be related to a confusion between the serial homology of the vertebrate pelvic and pectoral appendages as a whole, and the serial homology of the specific soft- and hard-tissue structures of the tetrapod Forelimbs and hindlimbs, leading to an even more crucial and puzzling question being overlooked: why are the skeletal and particularly the muscle structures of the Forelimb and hindlimb actually so strikingly similar to each other? Herein we provide an updated discussion of these questions and test two main hypotheses: (i )t hat the similarity of the limb muscles is due to serial homology; and (ii )t hat tetrapods that use hindlimbs for a largely exclusive function (e.g. bipedalism in humans) exhibit fewer cases of similarity between Forelimbs and hindlimbs than do quadrupedal species. Our review shows that of the 23 arm, forearm and hand muscles/muscle groups of salamanders, 18 (78%) have clear ‘topological equivalents’ in the hindlimb; in lizards, 14/24 (58%); in rats, 14/35 (40%); and in modern humans, 19/37 (51%). These numbers seem to support the idea that there is a plesiomorphic similarity and subsequent evolutionary divergence, but this tendency actually only applies to the three former quadrupedal taxa. Moreover, if one takes into account the total number of ‘correspondences’, one comes to a surprising and puzzling conclusion: in modern humans the number of Forelimb muscles/muscle groups with clear ‘equivalents’ in the hindlimb (19) is substantially higher than in quadrupedal mammals such as rats (14), lizards (14) and even salamanders (18). These data contradict the hypothesis that divergent functions lead to divergent morphological structures. Furthermore, as we show that at least five of the 19 modern human adult Forelimb elements that have a clear hindlimb ‘equivalent’ derive from embryonic anlages that are very different from the ones giving rise to their adult hindlimb ‘equivalents’, they also contradict the hypothesis that the similarity in muscle structures between the Forelimb and hindlimb of tetrapods such as modern humans are due to their origin as serial homologues. This similarity is instead the result of phylogenetically independent evolutionary changes leading to a parallelism/convergence due to: (i )d evelopmental constraints, i.e. similar molecular mechanisms are involved (particularly in the formation of the neomorphic hand), but this does not necessarily mean that similar anlages are used to form the similar adult structures; (ii) functional constraints, related to similar adaptations; (iii )t opological constraints, i.e. limited physical possibilities; and even (iv )p hylogenetic constraints, which tend to prevent/decrease the occurrence of new homoplasic similarities, but also help to keep older, ancestral homoplasic resemblances.

Louis J Soslowsky - One of the best experts on this subject based on the ideXlab platform.

  • transient decreases in Forelimb gait and ground reaction forces following rotator cuff injury and repair in a rat model
    Journal of Biomechanics, 2010
    Co-Authors: Joseph J Sarver, Michael I Dishowitz, Louis J Soslowsky

    Abstract Due to inadequate healing, surgical repairs of torn rotator cuff tendons often fail, limiting the recovery of upper extremity function. The rat is frequently used to study rotator cuff healing; however, there are few systems capable of quantifying Forelimb function necessary to interpret the clinical significance of tissue level healing. We constructed a device to capture images, ground reaction forces and torques, as animals ambulated in a confined walkway, and used it to evaluate Forelimb function in uninjured control and surgically injured/repaired animals. Ambulatory data were recorded before (D–1), and 3, 7, 14, 28 and 56 days after surgery. Speed as well as step width and length were determined by analyzing ventral images, and ground reaction forces were normalized to body weight. Speed averaged 22±6 cm/s and was not affected by repair or time. Step width and length of uninjured animals compared well to values measured with our previous system. Forelimbs were used primarily for braking (−1.6±1.5% vs +2.5±0.6%), bore less weight than hind limbs (49±5% vs 58±4%), and showed no differences between sides (49±5% vs 46±5%) for uninjured control animals. Step length and ground reaction forces of the repaired animals were significantly less than control initially (days 3, 7 and 14 post-surgery), but not by day 28. Our new device provided uninjured ambulatory data consistent with our previous system and available literature, and measured reductions in Forelimb function consistent with the deficit expected by our surgical model.