Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Forelimb”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 271 records · Page 15Linked to original sources
PubMed1982

Radioactive deoxyglucose uptake into forelimb muscles in task performing monkeys.

Incorporation of [14C]2-deoxy-d-glucose (2-DG) into forelimb muscles of task-performing monkeys was studied. Extensor muscles of used forelimbs showed a significant increase in 2-DG uptake; they were ext.dig.2nd and 3rd, ext.dig.com., ext.carp.rad. and ext.carp.uln. On the other hand, flexor muscles in the used forelimb did not show such a significant increase in 2-DG uptake. Muscles of non-used limbs, flexors or extensors, did not show a significant 2-DG uptake.

Animals↗
PubMed1990

Effects of bilateral lesions of the cerebellar interpositus nucleus on the conditioned forelimb flexion reflex in mice.

Three groups of mice, unoperated controls, sham and lesioned, were submitted to an associative conditioning of forelimb flexion reflex (FFR). Light and tone constituted the conditioned stimulus (CS) paired with a forelimb electric shock, the unconditioned stimulus (UCS). The first two groups were able to acquire an appropriate conditioned response. In the third group, each animal received a bilateral lesion of the cerebellar interpositus nucleus (IN). The subjects of this group were unable to acquire the conditioning. When bilateral lesions of the IN were done after the acquisition, no effect of the lesions could be detected during retention test sessions 10 days after surgery, by comparison with sham controls. It is therefore concluded that the cerebellar interpositus nucleus is an essential part of the circuit for the acquisition of associative conditioning of the forelimb flexion response in mice, but not for the retention of this task. Moreover, no direct sensorimotor effect of the lesion on performance itself could be evoked.

Animals↗
PubMed1990

Neuronal dropout is greater in hindlimb motor nuclei than in forelimb motor nuclei in aged rats.

The number of forelimb, ulnar (U) and hindlimb, medial gastrocnemius (MG) motoneurons labeled with retrograde axonal transport of horseradish peroxidase was examined in young and aged rats. No significant difference was found between the mean number of U motoneurons in young and aged rats, whereas the mean number of MG motoneurons was significantly lower in aged rats than in young rats. These results suggest that motoneuronal dropout is greater in hindlimb motor nuclei than in forelimb motor nuclei, which may contribute to differential changes in forelimb and hindlimb muscles with increasing age.

Aging↗
PubMed1991

Impairments in reaching during reversible inactivation of the distal forelimb representation of the motor cortex in the cat.

We report changes in the performance of a prehension task in the cat following focal inactivation of the rostrolateral subregion of the distal forelimb area of motor cortex (MCx) produced by muscimol microinjection. Animals reached into a cylindrical target to retrieve a morsel of food. Movements consisted of distinct lift and forward thrust phases following which the food was grasped and retrieved. In separate blocks of trials an obstacle was inserted in the path of the limb. Impact evoked an immediate compensatory trajectory change to bypass the obstruction and, on subsequent trials, an adaptive trajectory change to avoid impact. Inactivation produced three major defects: (1) uncompensated aiming biases to a location above the target; (2) loss of coordination of the grasp and food retrieval; and (3) impairment in trajectory adaptation to avoid impact of the limb with an obstacle. Thus, focal inactivation of the distal forelimb area of MCx produced disordered control of all forelimb joints. The impairment in trajectory adaptation and failure to compensate for aiming biases suggests that the MCx is important in motor learning.

Animals↗
PubMed1988

Motor functions of the striatum in the rat: critical role of the lateral region in tongue and forelimb reaching.

The findings of this study indicate a critical and selective role of the rat's lateral striatum in performance of tongue and forelimb reaching. To test the hypothesis of regional specificity of motor control in the striatum, the effects of bilateral, ibotenate-induced lesions of either the lateral or the medial regions of the striatum on reaching movements of the tongue and the forelimbs were examined. Lesions of the lateral striatum caused severe and chronic impairments of movement initiation, postural synergisms and amplitude of both tongue and forelimb reaches. In contrast, lesions of the medial striatum produced mild or no chronic alterations of these motor parameters. These findings support the hypothesis of a selective role of the lateral striatum in the initiation and execution of reaching movements.

Animals↗
PubMed1994

Motor cortex and pyramidal tract axons responsible for electrically evoked forelimb flexion: refractory periods and conduction velocities.

Double-pulse methods are used here to measure the refractory periods and conduction velocities of the pyramidal tract axons which cause forelimb flexion in pentobarbital anesthetized rats. In the refractory period experiments, conditioning and test pulses were delivered to the motor cortex, the ipsilateral internal capsule, or the ipsilateral pyramid, and the maximum force exerted by the contralateral forelimb was measured at various conditioning-test intervals. The movements increased as conditioning-test interval increased from 0.5 to 1.0 ms in pyramid sites, from 0.6 to 1.5 in internal capsule sites, and from 0.6 to 2.0 ms in surface cortical sites, suggesting longer refractory periods for the substrates at more rostral sites. In cortical sites, as the conditioning-test interval increased from 4.0 to 20.0 ms, the movements decreased gradually to the single-pulse level, suggesting decreasing temporal summation at longer conditioning-test intervals. In the collision experiments, when conditioning pulses were delivered to one site and test pulses to a second site, the movements increased at conditioning-test intervals that were longer by 0.5-1.3 ms than the refractory periods in either site. This suggests that collisions occurred between orthodromic and antidromic action potentials in the pyramidal tract axons responsible for the limb movement. The collision-like increase was greater between internal capsule and pyramid than between cortex and pyramid, or between cortex and internal capsule. The estimated conduction times were 0.9-1.5 ms between cortex and pyramid, 0.4-0.8 ms between cortex and internal capsule, and 0.5-0.8 ms between internal capsule and pyramid. The range of conduction velocities, therefore, was quite narrow between all pairs (8.8-16.8 m/s). The largest pyramidal tract axons appear to be responsible for most of the force of forelimb flexion in pentobarbital anesthetized rats.

Animals↗
PubMed1990

Raccoon forelimb motorsensory cortex: I. Somatic afferent inputs to different cytoarchitectonic areas.

The distribution of potentials evoked in and around forelimb MsI by graded electrical stimulation of forelimb nerves has been studied in the raccoon (Procyon lotor). These data have been correlated with cytoarchitectonic characteristics of pericruciate cortical tissue. Potentials evoked by cutaneous nerve stimulation were widely distributed in MsI and SmI, but were smaller in amplitude and of longer latency in MsI than in SmI. Stimulation of ulnar, median or deep radial nerve at 1-1.4T, a strength considered to activate only Group I muscle afferent fibers, caused evoked potentials in a localized region mostly confined to posterior sigmoid gyrus. On the basis of cytoarchitectonic features it is concluded that: a) Anterior sigmoid gyrus, to near the level of the tip of the cruciate sulcus, is area 6 cortex; b) The lateral portion of the posterior sigmoid gyrus, cortex comprising the caudal bank of the cruciate sulcus and cortex surrounding the lateral tip of the cruciate sulcus is area 4 cortex; c) The middle portion of the posterior sigmoid gyrus, almost to the lip of the cruciate sulcus rostrally and extending onto the rostral bank of the ascending coronal and postcruciate sulci caudally, is area 3a cortex. The cortical focus for Group I afferent-evoked potentials coincides with area 3a cortex. It is concluded that forelimb MsI of raccoon is organized in a fashion similar to MsI of cats and monkeys.

Animals↗
PubMed1990

Raccoon forelimb motorsensory cortex: II. Somatosensory inputs to single neurons.

Somatosensory input to 431 neurons in MsI has been studied in unanesthetized, paralyzed raccoons (Procyon lotor). The type of sensory input to neurons in lateral sigmoid gyrus (cytoarchitectonic area 4) and in posterior sigmoid gyrus (areas 4 and 3a) was not significantly different. Of these neurons, 36% were activated by superficial cutaneous stimulation (touch, tap or hair deflection) and 26% by deep stimulation (pressure or joint movement). Mute neurons (not driven by any form of peripheral stimulation tested, or vaguely driven) comprised 38% of the sample. Only 4% of anterior sigmoid gyrus (area 6) neurons responded to superficial or deep stimulation; 96% were mute. The majority of MsI neurons had small (less than or equal to 20 cm2) peripheral receptive fields (PRFs). There was a statistically significant trend for PRF size to decrease along the proximal-distal axis of the forelimb. The area of MsI digit PRFs was significantly larger than the area of SmI digit PRFs. Comparing the data for raccoon MsI with information from the literature for cats and monkeys suggests that the type and amount of somesthetic afferent input to forelimb MsI is related to the behavioral uses to which each animal puts the forelimb.

Afferent Pathways↗
PubMed1989

Characterization and development of metallothionein in fetal forelimbs, brain and liver from the mouse.

The presence of the low molecular weight protein metallothionein (MT) has been investigated in fetal forelimbs, brain and liver from the mouse with the aim of using the protein as a biochemical marker for the early recognition of potential teratogenic agents in the future. Forelimbs, brain and liver were taken from mouse fetuses at ages ranging from 12 to 18 d. Each type of organ was homogenized and centrifuged at 9000 x g. The analysis of MT in the supernatants (S9) with the Cd-heme saturation method detected in all three cases the presence of a low molecular weight, Cd-binding protein whose concentration increased with the age of the fetus. Analysis of the S9 fractions using gel- and anion exchange-chromatography and polyacrylamide gel electrophoresis demonstrated the existence of a protein analogue to the hepatic MT in forelimbs and brain.

Animals↗
PubMed2006

Colour-coded pellets increase the sensitivity of the staircase test to differentiate skilled forelimb performances of control and 6-hydroxydopamine lesioned rats.

The Montoya staircase test has previously been used to study the skilled forelimb performance of mice and rats following lesions and cell implants in different parts of the central nervous system. Here we describe a modification of the original test design which introduces differently coloured food pellets for each step, and present the results of the new and modified method. In this study unilaterally 6-hydroxydopamine (6-OHDA) lesioned rats and healthy control rats were used. The new evaluation of reaching and grasping movements takes into consideration the various levels of reaching difficulty. The coloured food pellets code for different steps of the staircase. The comparison between the original versus the modified test methods revealed significant differences most prominently on the lower steps. It is important to notice that the pattern of grasping movements in the hemiparkinsonian rats changes from precise reaching (prior to lesion) to shuffling and unsuccessfully trying to reach pellets. The observation of this change in behaviour would not have been obtained through the evaluation of the original staircase test. In summary, the modified staircase test introduces a colour-coded pellet system which obviously increases the test sensitivity and discloses new insights into the skilled forelimb use in a rat model of Parkinson's disease. It may therefore become a valuable tool in future studies related to plasticity-induced changes in skilled forelimb reaching and grasping movements.

Analysis of Variance↗
PubMed2004

Quantitative assessment of deficits and recovery of forelimb motor function after cervical spinal cord injury in mice.

A large proportion of spinal cord injuries (SCIs) in humans are at the cervical (C) level, but there are few tests to quantitatively assess forelimb motor function after cervical spinal cord injury in rodents. Here, we describe a simple and reliable technique for assessing forelimb grip strength over time. Female C57Bl/6 mice were trained on the Grip Strength Meter (GSM, TSE-Systems), then received a lateral hemisection of the spinal cord at level C5, C6, C7, or T1. Gripping ability by each forepaw was then tested for 4 weeks postinjury. Before injury, there was no significant difference in the force exerted by either forepaw. After hemisections at C5, C6, or C7, the forepaw ipsilateral to the injury was initially completely unable to grip (day 2 postinjury), and there was a slight transient decrease in the strength of the contralateral paw compared to presurgical levels. The ipsilateral forepaw exhibited no ability to grip until about 10-14 days postlesion, at which time grip reappeared and strength then recovered over a period of a few days to a level that was about 50% of preinjury levels. Grip strength was minimally and transiently affected by hemisection at T1. The grip strength analysis provides a convenient, quantitative measure of the loss and recovery of forelimb function after cervical injury.

Animals↗
PubMed2005

The porcine forelimb as a model for human flexor tendon surgery.

Technical skills have been shown to transfer very well from bench models to practical use. The central two rays of 30 forelimbs of pigs were dissected and anatomical observations were made. The rays contained deep and superficial flexor tendons enclosed in a fibro-osseous tunnel and these were present in all 60 specimens. The fibrous part of the tunnel had specific constant condensations in annular and oblique directions which were present in all 60 rays. The anatomy of the porcine forelimb digital flexor tendon system is sufficiently similar to the human system to be used as a model for surgeons wishing to master the technical aspects of zone II flexor tendon repair. This paper proposes the porcine forelimb as a bench model for zone II flexor tendon repair.

Animals↗
PubMed2003

Patterning of forelimb bud myogenic precursor cells requires retinoic acid signaling initiated by Raldh2.

Limb skeletal muscle is derived from cells of the dermomyotome that detach and migrate into the limb buds to form separate dorsal and ventral myogenic precursor domains. Myogenic precursor cell migration is dependent on limb bud mesenchymal expression of hepatocyte growth factor/scatter factor (Hgf), which encodes a secreted ligand that signals to dermomyotome through the membrane receptor tyrosine kinase Met. Here, we find that correct patterning of Hgf expression in forelimb buds is dependent on retinoic acid (RA) synthesized by retinaldehyde dehydrogenase 2 (Raldh2) expressed proximally. Raldh2(-/-) forelimb buds lack RA and display an anteroproximal shift in expression of Hgf such that its normally separate dorsal and ventral expression domains are joined into a single anterior-proximal domain. Met and MyoD are expressed in this abnormal domain, indicating that myogenic cell migration and differentiation are occurring in the absence of RA, but in an abnormal location. An RA-reporter transgene revealed that RA signaling in the forelimb bud normally exists in a gradient across the proximodistal axis, but uniformly across the anteroposterior axis, with all proximal limb bud cells exhibiting activity. Expression of Bmp4, an inhibitor of Hgf expression, is increased and shifted anteroproximally in Raldh2(-/-) limb buds, thus encroaching into the normal expression domain of Hgf. Our studies suggest that RA signaling provides proximodistal information for limb buds that counterbalances Bmp signaling, which in turn helps mediate proximodistal and anteroposterior patterning of Hgf expression to correctly direct migration of Met-expressing myogenic precursor cells.

Aldehyde Oxidoreductases↗
PubMed2000

CNS plasticity and assessment of forelimb sensorimotor outcome in unilateral rat models of stroke, cortical ablation, parkinsonism and spinal cord injury.

We have reviewed a battery of useful tests for evaluating sensorimotor function and plasticity acutely and chronically in unilateral rat models of central nervous system injury. These tests include forelimb use for weight shifting during vertical exploration in a cylindrical enclosure, an adhesive removal test of sensory function, and forelimb placing. These tests monitor recovery of sensorimotor function independent of the extent of test experience. Data are presented for four models, including permanent focal ischemia, focal injury to the forelimb area of sensorimotor cortex, dopaminergic neurodegeneration of the nigrostriatal system, and cervical spinal cord injury. The effect of the dendrite growth promoting factor, Osteogenic Protein-1 (OP-1) on outcome following permanent middle cerebral artery (MCA) occlusion was used as an example to illustrate how the tests can be applied preclinically. OP-1 showed a beneficial effect on limb use asymmetry in the cylinder test.

Animals↗
PubMed2003

Forelimb use after focal cerebral ischemia in rats treated with an alpha 2-adrenoceptor antagonist.

Atipamezole, a selective alpha(2)-adrenoceptor antagonist, enhances recovery of sensorimotor function after focal cerebral ischemia in rats. The aim of the present study was to further characterize the effects of atipamezole treatment combined with enriched-environment housing in ischemic rats by evaluating spontaneous exploratory activity in the cylinder test. The right middle cerebral artery (MCA) of rats was occluded for 120 min using the intraluminal filament method. Atipamezole (1.0 mg/kg) or 0.9% NaCl was administered on postoperative days 2 through 11 and 15, 19, and 23. Spontaneous behavior of rats in a transparent cylinder was videotaped before, and 6 and 23 days after surgery 20 min after drug administration. Constant asymmetry in forelimb use was observed in the cylinder test on postoperative days 6 and 23. Ischemic rats used the impaired forelimbs (contralateral to lesion) during lateral exploration less than did sham-operated rats (P<.001). Ischemic rats also preferred to turn contralateral to the lesion (P<.05). Atipamezole increased the simultaneous, but not independent, use of the forelimbs during lateral exploration (P<.05). The data suggest that noradrenergic manipulation does not significantly enhance recovery in a test that does not depend on practice following focal cerebral ischemia.

Adrenergic alpha-2 Receptor Antagonists↗
PubMed2001

Graded unilateral cervical spinal cord injury in the rat: evaluation of forelimb recovery and histological effects.

The purpose of this study was to develop a model of unilateral cervical (C4-C5) spinal cord contusion injury in the rat and to characterize the functional and histological consequences following three injury levels using a new weight-drop spinal cord injury device. We evaluated forepaw/forelimb and hindlimb functions by: (1) a horizontal ladder beam measuring paw misplacements and slips; and (2) the forelimb preference test which measures the forelimb used for pushing off to rear, for support, and to land on after rearing. Rats with a mild spinal cord injury displayed primarily a forepaw deficit (forepaw misplacements) for 8 weeks after injury. Paw preference also improved after injury, but failed to reach control levels even after 12 weeks. These rats had damage primarily to the rubrospinal, spinocervicothalamic, and the uncrossed lateral corticospinal tracts in the dorsolateral funiculus a well as some loss of the lateral spinothalamic tracts in the lateral funiculus. Rats with a moderate injury had a prominent forepaw deficit still evident at 12 weeks after injury as well as a mild but not significant hindlimb deficit. Paw preference improved slightly 12 weeks. There was a larger lesion in the dorsolateral and lateral funiculi than in mildly injured rats which extended into the ventrolateral funiculi. There was a significant loss of gray matter compared to rats with a mild injury. Rats with a severe injury displayed significant forelimb and hindlimb deficits throughout the 12 week testing period compared to rats with a mild or moderate injury, and also had a more severe paw preference bias (90%). The lesion encompassed the entire dorsolateral, lateral and ventrolateral funiculi with some disruption of the ventral funiculus. There was more significant gray matter necrosis compared to rats with either a mild or moderate injury. Thus, the spinal cord injury device we used may be useful for studying graded cervical spinal cord injury in rats and potential treatments or interventions, because both the behavioral and histological effects are reproducible and consistent.

Animals↗
PubMed2004

Consequences of forced disuse of the impaired forelimb after unilateral cortical injury.

Extreme over-reliance on the impaired forelimb following unilateral lesions of the forelimb representation area of the rat sensorimotor cortex (FL-SMC) leads to exaggeration of injury when overuse is begun during the first week, but not later periods, after injury. Behavioral impairment is partially worsened by the additional tissue loss. In the present study, we show that complete disuse of the impaired forelimb during the first post-operative week renders surviving tissue vulnerable to later overuse of the same limb, in effect extending the window of vulnerability in which use-dependent exaggeration of brain injury can occur. Behavioral recovery is disrupted by complete disuse, but the degree of impairment is variable depending on the nature of the behavioral test employed. Our results uphold the idea that mild rehabilitative training early after injury is beneficial, while either extreme overuse or complete disuse may disrupt functional recovery.

Animals↗
PubMed1999

Cortical injury impairs contralateral forelimb immobility during swimming: a simple test for loss of inhibitory motor control.

Most animal models of focal injury to the sensorimotor cortex have been aimed at detecting non-use or impairment of the limbs in specific tasks or during spontaneous exploratory behaviors. However, the inability to hold a limb still can be an equally disabling movement disorder. The present study investigated the loss of control of limb immobility that occurs following damage to the forelimb region of the rat sensorimotor cortex (FL-SMC). When swimming forward in a tank of water, adult rats typically hold both forepaws mostly motionless underneath the chin, using primarily the hindlimbs for stroking movements. Following a unilateral FL-SMC lesion, rats hold only the non-impaired forelimb immobile under the chin, and make 'immature' stroking movements with the impaired forelimb. We have devised a simple means of assessing and quantifying this deficit. While the criterion for most tests of motor recovery involves appropriate movement of an impaired limb, this test depends on adequate inhibition of movement as the norm, and may be a useful way to assess the loss of inhibitory motor control and the efficacy of potential restorative interventions.

Animals↗