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 217 records · Page 12Linked to original sources
PubMed1988

Nonoverlapping thalamocortical connections to normal and deprived primary somatosensory cortex for similar forelimb receptive fields in chronic spinal cats.

The fluorescent dye retrograde tracing technique, using fast blue in combination with fluorogold, was used to examine thalamocortical projections from the ventrobasal complex to primary somatosensory cortex in chronic spinal cats that sustained T12 cord transection at 2 weeks of age. Following cord transection at this age, it has been shown that forelimb afferents can excite the deprived hindlimb projection zone, in addition to the region of somatosensory cortex that they normally occupy (McKinley et al., 1987). These two regions of cortex are separated by over 10 mm, thus facilitating the determination of whether the forelimb representation in "hindlimb cortex" is derived from the sector of the ventrobasal complex of the thalamus representing the forelimb, hindlimb, or both. Injections of the two dyes into separate regions of the cortex that were excited by the same peripheral forelimb receptive fields produced single labeling of two nonoverlapping clusters of thalamic neurons. This finding suggests that the projections for these two areas are independent and distinct, and indicates that altered thalamocortical projections do not contribute the critical component underlying reorganizational changes observed at the cortical level after spinal cord transection. It is hypothesized that the degree of reorganization required to achieve the magnitude of change observed in the cortex must occur below the level of the thalamocortical relay.

Animals↗
PubMed1993

Comparison of the connectional properties of the two forelimb areas of the rat sensorimotor cortex: support for the presence of a premotor or supplementary motor cortical area.

The existence of multiple motor cortical areas that differ in some of their properties is well known in primates, but is less clear in the rat. The present study addressed this question from the point of view of connectional properties by comparing the afferent and efferent projections of the caudal forelimb area (CFA), considered to be the equivalent of the forelimb area of the primary motor cortex (MI), and a second forelimb motor representation, the rostral forelimb area (RFA). As a result of various tracing experiments (including double labeling), it was observed that CFA and RFA had reciprocal corticocortical connections characterized by preferential, asymmetrical, laminar distribution, indicating that RFA may occupy a different hierarchical level than CFA, according to criteria previously discussed in the visual cortex of primates. Furthermore, it was found that RFA, but not CFA, exhibited dense reciprocal connections with the insular cortex. With respect to their efferent projection to the basal ganglia, it was observed that CFA projected very densely to the lateral portion of the ipsilateral caudate putamen, whereas the contralateral projection was sparse and more restricted. The ipsilateral projection originating from RFA was slightly less dense than that from CFA, but it covered a larger portion of the caudate putamen (in the medial direction); the contralateral projection from RFA to the caudate putamen was of the same density and extent as the ipsilateral projection. The reciprocal thalamocortical and corticothalamic connections of RFA and CFA differed from each other in the sense that CFA was mainly interconnected with the ventrolateral thalamic nucleus, while RFA was mainly connected with the ventromedial thalamic nucleus. Altogether, these connectional differences, compared with the pattern of organization of the motor cortical areas in primates, suggest that RFA in the rat may well be an equivalent of the premotor or supplementary motor area. In contrast to the corticocortical, corticostriatal, and thalamocortical connections, RFA and CFA showed similar efferent projections to the subthalamic nucleus, substantia nigra, red nucleus, tectum, pontine nuclei, inferior olive, and spinal cord.

Afferent Pathways↗
PubMed1995

Long-term age-related consequences of forelimb damage upon expression of primary afferent phenotypes in the cervical dorsal horn.

Rats that sustained forelimb removal on either embryonic day 16 (E-16) or the day of birth (P-0), or transection of the brachial plexus in adulthood, had sections through the cervical dorsal horn stained for galanin, calcitonin gene-related peptide (CGRP), or the plant lectin Bandieria simplicifolia-I (BS-I) 35-50 days after these lesions. The results of these experiments demonstrated age-related differences in the effects of peripheral nerve damage upon the distributions of each of these three primary afferent markers in the dorsal horn. Damage to the brachial plexus in adulthood caused a significant increase in the density of galanin immunoreactivity in the medial portion of layers I and II and the appearance of galanin immunoreactivity in layers III and IV of the cervical dorsal horn. Such lesions resulted in significant reductions in the density of CGRP immunoreactivity in layers I and II and of BS-I binding in lamina II. Forelimb removal on the day of birth resulted in no significant change in the density of galanin immunoreactivity in layers I and II, but in the appearance of galanin-immunoreactive fibers in layers III-V. Neonatal forelimb removal resulted in no significant change in the density of CGRP immunoreactivity in layers I and II, but in a significant reduction in the density of BS-I binding in the medial portion of lamina II. Removal of the forelimb on E-16 caused a significant increase in the density of galanin immunoreactivity in layers III-V, but had no significant effect on the density or distribution of either CGRP immunoreactivity or BS-I binding in the cervical dorsal horn. These results suggest that peripheral nerve damage at all ages may cause an up-regulation of galanin in a wider distribution of ganglion cell types than was previously thought to be the case, and that there are different sensitive periods for lesion-induced, long-term changes in the innervation of the dorsal horn by CGRP- and BS-I-positive primary afferent axons.

Afferent Pathways↗
PubMed2001

Enriched rehabilitative training promotes improved forelimb motor function and enhanced dendritic growth after focal ischemic injury.

Chronic impairment of forelimb and digit movement is a common problem after stroke that is resistant to therapy. Previous studies have demonstrated that enrichment improves behavioral outcome after focal ischemia; however, postischemic enrichment alone is not capable of enhancing fine digit and forelimb function. Therefore, we combined environmental enrichment with daily skilled-reach training to assess the effect of intensive task-specific rehabilitation on long-term functional outcome. Rats were subjected to either endothelin-1-induced focal ischemia or sham surgery and subsequently designated to enriched-rehabilitation or standard-housing treatment groups starting 15 d after ischemia. Functional assessment of the affected forelimb at 4 and 9 weeks after treatment revealed that ischemic plus enrichment (IE) animals had improved approximately 30% on the staircase-reaching task and were indistinguishable from sham animals for both latency and foot faults in a beam-traversing task. In contrast, ischemic plus standard (IS) animals remained significantly impaired on both tasks. Interestingly, both ischemic groups (IE and IS) relied on the nonaffected forelimb during upright weight-bearing movements, a pattern that persisted for the duration of the experiment. Dendritic arborization of layer V pyramidal cells within the undamaged motor cortex was examined using a Golgi-Cox procedure. IE animals showed enhanced dendritic complexity and length compared with both IS and sham groups. These results suggest that enrichment combined with task-specific rehabilitative therapy is capable of augmenting intrinsic neuronal plasticity within noninjured, functionally connected brain regions, as well as promoting enhanced functional outcome.

Animals↗
PubMedDate not supplied

[Influence of the neck muscles deafferentation on the natural head-forelimb coordination in dogs].

We studied the influence of the neck muscles deafferentation on the natural head-forelimb coordination. This coordination exists in intact dogs at the early stage of acquisition of the instrumental feeding reaction of tonic forelimb flexion aimed at holding a cup with meat during eating when the head is bent down to foodwell. In untrained dogs, the forelimb flexion is preceded by lifting the head bent down to the food; the following lowering of the head leads to extension of the flexed forelimb. For performing the instrumental reaction, the innate coordination has to be rearranged into the opposite one. It is achieved only by learning. It was shown that deafferentation of the neck muscles, which leads to a loss of the neck reflex, did not destroy the innate coordination and did not facilitate its rearrangement during the instrumental conditioning.

Animals↗
PubMed1990

Forelimb movements in the cat; kinetic features and neuronal control.

The role of defined descending pathways in the control of forelimb movements in cats was investigated in behavioural experiments. The movements studied were "target-reaching" (i.e. the movement used to reach for food) and "food-taking" (i.e. the movement used for grasping a piece of food and for bringing it to the mouth). The interesting feature of these movements is that the neuronal systems mediating the descending commands to motoneurones have previously been investigated. The command for target-reaching can be mediated by propriospinal neurones (PNs) in the C3-C4 segments and food-taking depends on interneurones in the forelimb segments (C6-Th1). The descending control of food-taking was investigated with serial lesions. The movement is normally abolished after a lesion of the dorsal part of the lateral funiculus in C5/6 interrupting the input from the cortico- and rubrospinal tracts (CST/RST) to the forelimb segments. If a similar lesion was made serially in two sessions with an initial lesion transecting the CST with minimal RST damage, the movement was not abolished when the remaining rubrospinal fibres were transected one month later; it was performed in the first postoperative test. Food-taking could now be abolished by a ventral lesion in C2. It is suggested that rubrospinal fibres remaining after the first lesion induced ventral reticulospinal fibres to mediate the command for the movement. The C3-C4 PNs receive input from the cortico-, rubro-, tecto- and reticulospinal tracts. The hypothesis that the subcortical systems may update a cortical command en route to motoneurones was investigated in cats trained to perform reaching to different targets. The position of the wrist was recorded with a SELSPOT system. If the position of the target was shifted during the movement, a correction was initiated with short latency (60-70 ms). A transection of the input from the CST and RST to interneurones in the forelimb segments so that the movements depended solely on the C3-C4 PNs did not appear to affect the corrections, but an additional ventral C2 lesion prolonged the response latency. A lesion transecting axons of the C3-C4 PNs changed the kinematics of the corrections with ataxia in the initial postoperative period and enhanced brake of protraction when the ataxia had subsided. It is postulated that the command for switching of target-reaching can be mediated via the C3-C4 PNs and it is suggested that fast switching of target-reaching may be evoked via the input from ventral tecto- and tecto-reticulospinal pathways; other routes are discussed.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1990

CGRP-mediated changes in segmental resistances in the canine forelimb.

Calcitonin gene-related peptide (CGRP) is a 37 amino acid peptide which is found in high concentrations in the perivascular nerves innervating the resistance vessels of the peripheral circulation. In the current study we have infused CGRP at three infusion rates (.01, .1 and 1.0 micrograms/min into the brachial artery for thirty minutes at each infusion rate) in the isolated, innervated canine forelimb perfused at natural flow. We measured large artery and vein pressures, small artery and vein pressures and blood flows in both the skin and skeletal muscle circulations for the calculation of total and segmental (large artery, small vessel and large vein) vascular resistances. Infusion of the lowest dosage of CGRP produced slight vasodilation in some animals but did not significantly alter the mean resistances of all the animals as a group. The middle dosage resulted in a 55% decrease in total forelimb resistance and a small but significant decrease in systemic arterial pressure. The highest dosage of CGRP resulted in a 65% decrease in total forelimb resistance and a 34% decrease in systemic arterial pressure. The decreases in forelimb resistances were equally distributed between skin and muscle and were manifested in both large artery and small vessel resistances. The potent vasodilatory effects of CGRP and its concentration in perivascular nerves innervating the resistance vessels of the peripheral circulation suggests a potential role for CGRP in control of circulatory function under normal and/or pathophysiological conditions.

Animals↗
PubMed1988

Pattern of blood vessels in forelimbs of three strains of mice.

A technique was developed for visualizing the pattern of arteries in the adult mouse forelimb. The aorta was cannulated and injected with blue stained Batson's Number 17 Anatomic Compound to perfuse the forelimb arteries; the ossified skeleton was stained and the soft tissues were cleared, making it possible to examine the entire arterial system in the intact specimen. The pattern of distribution of arteries were compared in 120 forelimbs from three strains of mice, two inbred and one hybrid. Significant differences between the three strains were found for 9 of 16 variations evaluated. Differences in the point of origin of vessels were the most common; differences in the fusion of vessels, the extension of vessels and the presence of extra vessels were also identified. The patterns were much more constant in the two inbred strains than in the hybrid strain, suggesting the importance of genetic factors in determining the arterial pattern. Absence of major vessels and an abnormal persistence of embryonic vessels, which have been observed in association with skeletal malformations, were not observed in any of the 120 normal adult mouse forelimbs examined.

Animals↗
PubMed1978

Effects of locally and systemically infused bradykinin on transvascular fluid and protein transfer in the canine forelimb.

Local intra-arterial infusions of bradykinin into canine forelimbs perfused either naturally or at constant inflow markedly increase skin lymph protein concentration promoting edema formation. However, prolonged systemic infusions of this agent either intravenously or into the left ventricular chamber, in blood concentrations calculated to exceed those that produce massive protein and fluid efflux on local administration, causes only minimal increases in lymph protein concentration, and in naturally perfused forelimbs promotes extravascular fluid reabsorption rather than net fluid filtration. Local infusions of bradykinin fail to alter aortic pressure whereas systemic infusions produce a profound but transient decrease in this variable. Moreover, the local intra-arterial infusion of bradykinin into forelimbs perfused at constant inflow fails to increase skin lymph protein concentration after 60 minutes of systemic hypotension. In contrast to bradykinin alone, the simultaneous infusion of bradykinin and norepinephrine or bradykinin and isoproterenol fails to increase skin lymph protein concentration. The antagonism of the bradykinin protein efflux by both norepinephrine and isoproterenol can be prevented by prior treatment with propranolol. These data suggest that the liberation of catecholamines may account, in part, for the minimal increases in forelimb protein efflux during systemic infusions of bradykinin relative to that produced by local intra-arterial infusions of this agent.

Animals↗
PubMed1980

Equine postanesthetic forelimb lameness: intracompartmental muscle pressure changes and biochemical patterns.

Intracompartmental muscle pressures were recorded from the right and left forelimbs (extensor carpi radialis, triceps brachii) of healthy horses maintained in left lateral recumbency while under deep halothane anesthesia for 180 to 240 minutes. Cardiac output, blood pressure, blood gases, and acid-base status were monitored throughout the anesthesia, and electrolyte levels (Ca2+, P+, K+, Cl-, Na+) and enzyme activities (aspartate aminotransferase (AST), creatine phosphokinase (CPK), and blood lactate) were monitored for 7 days. Postanesthetic forelimb lameness was produced in 5 of the 6 horses with this prolonged anesthetic regime. This lameness was associated with muscle plaque formation and clinical signs which were similar to the forelimb lameness sometimes seen in horses after surgical anesthesia. Plasma protein, serum calcium, plasma sodium, and blood urea nitrogen concentrations did not change, whereas significantly increased hematocrit, plasma potassium, and serum inorganic phosphate values were seen at the end of anesthesia, along with a decrease in plasma chloride values. Blood lactate, serum AST, and serum CPK activities were significantly high in the postanesthetic period, although the sequence of the changes differed. Intracompartmental muscle pressures were higher in the left forelimb adjacent to the floor (contact limb), and in the instance of the triceps of the contact limb, the pressures were sufficiently high (greater than 30 mm of Hg) that they may have compromised capillary blood flow. However, these high intracompartmental muscle pressures did not persist when positional changes of the horses were introduced at the end of the anesthetic period. There was no correlation between the severity of postanesthetic lameness and any of the measured values. The results demonstrate an experimentally induced postanesthetic lameness which was primarily related to the development of a myositis. Although the causative factors of this myositis may be multiple, the present study implicates local hypoxia in that increased blood lactate and inorganic phosphate values preceded that increased CPK activity. Intracompartmental muscle pressure in the contact limb were possibly high enough to have restricted local capillary blood flow.

Anesthesia, Inhalation↗
PubMed1993

Anatomical and functional changes in the organization of the cuneate nucleus of adult rats after fetal forelimb amputation.

A previous study has shown that fetal forelimb removal in the rat results in an increase in the size of the hindlimb representation in primary somatosensory cortex and suggested that this anomalous cortical organization may have resulted from alterations in the primary afferent innervation of the dorsal column nuclei (Killackey and Dawson, 1989). The present study used both anatomical and electrophysiological techniques to examine the effects of fetal forelimb amputation on the dorsal column nuclei. Rats sustained forelimb removals on embryonic day 16 and were used in terminal experiments when they reached adulthood (> 60 d of age). Analysis of cytochrome oxidase-stained sections demonstrated that the cuneate nucleus ipsilateral to the lesion decreased in volume by an average of 36.7% (N = 7, p < 0.001, paired t test), but there was no corresponding increase in the volume of the gracile fasciculus and nucleus. Bilateral application of HRP to the sciatic nerves demonstrated that axons that innervate only the gracile nucleus on the intact side of the brainstem were present in the cuneate nucleus on the deafferented side. Injection of HRP into the skin overlying the point of the amputation (the stump) indicated that axons innervating this region filled most of the dorsal one-half of the shrunken cuneate nucleus and overlapped with the sciatic nerve afferents innervating the cuneate on this side. Mapping the receptive fields of multiple unit clusters demonstrated that most recording sites in the shrunken cuneate nucleus were activated by inputs from the stump and adjacent skin. In addition, 9.1% (N = 30) of such unit clusters (N = 328) could also be excited by stimulation of the hindlimb. These were observed in only three of the nine experiments. Unit clusters with split receptive fields including the skin overlying the stump and the hindlimb were located throughout the rostrocaudal extent of the cuneate nucleus. These results indicate that fetal forelimb amputation results in anatomical expansion of the central projections of hindlimb afferents into the cuneate nucleus. This anatomical organization appears weakly expressed in the receptive fields of cuneate neurons.

Afferent Pathways↗
PubMed1995

Forelimb akinesia in the rat Parkinson model: differential effects of dopamine agonists and nigral transplants as assessed by a new stepping test.

Methods for the assessment of akinesia in the unilateral rat Parkinson model have so far been lacking. The experiments reported here evaluate the usefulness of a new "stepping test" to monitor forelimb akinesia in rats with unilateral 6-hydroxydopamine (6-OHDA) lesions of the mesencephalic dopamine (DA) system, and to assess the ability of DA-receptor agonists and fetal DA neuron transplants to reverse these deficits. The 6-OHDA lesion induced marked and long-lasting impairments in the initiation of stepping movements with the contralateral paw. Systemic injections of low doses (chosen to be subthreshold for induction of rotation) of the mixed D1 and D2 receptor agonist apomorphine, the D1-selective agonist SKF 38393, and to a lesser extent also the D2-selective agonist quinpirole were effective in reversing these deficits. Similar effects was seen after a subrotational dose of L-dopa, whereas amphetamine had no effect. Fetal nigral transplants, implanted as multiple deposits in the ipsilateral caudate-putamen and substantia nigra, restored initiation of stepping to a similar degree as the DA agonists. Nigral grafts placed in substantia nigra alone were also effective, although the improvement was less pronounced. Apomorphine, at a dose effective in the lesion-only animals, had no additive effect in the grafted rats, whereas amphetamine appeared to further improve stepping in the rats with intranigral transplants. Identical experiments were performed on skilled forelimb use in the so-called staircase test. Interestingly, neither the DA agonist drugs nor the nigral transplants had any effects on the lesion induced deficits in this more complex task. The results show that forelimb stepping is a highly useful test to monitor lesion-/and transplant-induced changes in forelimb akinesia, a behavioral parameter that may be analogous to limb akinesia and gait problems seen in patients with Parkinson's disease.

2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-ben↗
PubMed1983

Levels of cyclic GMP and cyclic AMP in regenerating forelimbs of adult newts following denervation.

The effect of short-term denervation (0, 12, 24, and 72 hours) on the levels of cyclic 3'5'-guanosine monophosphate (cGMP) and cyclic 3'5'-adenosine monophosphate (cAMP) in adult newt (Notophthalmus viridescens) forelimbs at 15, 22, and 35 days of regeneration was investigated. Regenerate blastema and stump cyclic nucleotide levels were compared with those of the contralateral intact forelimb and hindlimb, with levels in the normally regenerating blastema, and with levels measured in the forelimbs of intact, nonoperated animals. Variations in cyclic nucleotide levels occurred according to regeneration stage and tissue type. Changes in level were noted immediately upon denervation and subsequently at other sample times in all regenerate and control series. Parallel fluctuations occurred in regenerate stump and contralateral intact forelimbs. Our results from nonamputated denervated and sham-denervated animals indicate that short-term, denervation-associated cyclic nucleotide fluctuations cannot be attributed solely to the loss of innervation.

Animals↗
PubMed2001

Quantitative assessment of forearm muscle size, forelimb grip strength, forearm bone mineral density, and forearm bone size in determining humerus breaking strength in 10 inbred strains of mice.

Bone strength is an important clinical endpoint of osteoporosis research. The evaluation of the relative importance of bone and muscle components to bone strength has widespread implications for the understanding and preventing of osteoporosis. The objectives of this study were to understand the interrelationship between the different components of the muscular skeletal system and to determine the effect of forearm muscle size, forelimb grip strength, forearm bone mineral density (BMD), and forearm bone size on the humerus breaking strength among 10 inbred strains of mice. The forearm muscle size was measured using a peripheral quantitative computed tomography (pQCT). The forearm BMD and forearm bone size were measured using a PIXIMUS Densitometer. The forelimb grip strength and humerus breaking strength were measured using an Instron Mechanical Tester. Significant correlations were found among the five regional phenotypes. All variables have a moderately high genetic component with heritability estimates of 0.83 for forelimb grip strength, 0.76 for forearm muscle size, 0.6 for forearm BMD, 0.63 for forearm bone size, and 0.68 for humerus breaking strength. Forward stepwise multiregression analysis showed that the forearm BMD, forelimb grip strength, and forearm bone size were three major determinants of bone strength and explained 61% of the variation in bone breaking strength. These data suggest that evaluation of these three parameters together, rather than BMD alone, is a more effective, noninvasive approach for predicting fracture risk.

Absorptiometry, Photon↗
PubMed1982

The effect of elbow joint afferent discharge on transmission in forelimb flexion reflex pathways to biceps and triceps brachii in decerebrate cats.

The present experiments were performed to investigate the influence of elbow joint afferent discharge on the excitability of reflex arcs mediating flexion withdrawal and crossed extensor reflexes in the forelimb muscles of decerebrate cats. The excitability of flexion withdrawal and crossed extensor reflexes in forelimb muscles was shown to be modulated by elbow joint position. Flexion withdrawal reflexes were most easily elicited when the elbow was extended and crossed extensor reflexes were most easily elicited when the elbow was flexed. This modulation of transmission was not confined to reflex pathways projecting to muscles acting at the elbow but also included pathways to muscles acting at the wrist and shoulder in addition to muscles in the contralateral forelimb. The changing excitability of reflex pathways caused by elbow movement was unaltered by degloving the skin covering the joint and tenotomy of the medial head of triceps and the long head of biceps. However, modulation of reflex excitability by joint movement was totally abolished by local anaesthesia of the joint in an otherwise intact limb. Thus, the present experiments indicate that transmission in forelimb flexion reflex pathways can be powerfully influenced by elbow joint afferent discharge.

Animals↗
PubMed1996

Metabolic activity pattern in the motor and somatosensory cortex of monkeys performing a visually guided reaching task with one forelimb.

The [14C]deoxyglucose method was used to map the metabolic activity in the primary somatosensory and motor cortex in monkeys (Macaca nemestrina) performing a unimanual task. The task required visually guided reaching and target holding at a rate of about 10 movements per min. The entire dorsoventral extent of the cortical region lying between the posterior crown of the arcuate and the anterior crown of the intraparietal sulci was reconstructed on the sagittal plane, from horizontal sections aligned on the fundus of the central sulcus. The metabolic mapping of the control monkey demonstrated homogeneous activity all around the central sulcus, bilaterally. The mapped activity in the performing monkeys displayed two different patterns. The first pattern, contralateral to the moving forelimb, was characterized by several discrete regions of increased metabolic activity, which were symmetrically distributed in a mirror image fashion around the fundus of the central sulcus. These activated regions correspond to the lower body, forelimb, and mouth areas of representation of body parts in previously reported maps in primary motor and somatosensory cortical areas. The second activity pattern ipsilateral to the moving forelimb, displayed activated somatosensory and motor regions corresponding only to the lower body, and mouth representations. Our study provides a continuous, high resolution map of activity pattern in the entire primary motor and somatosensory cortices, which demonstrates that the reaching forelimb is controlled by a discrete subregion in the contralateral somatosensorimotor cortex, whereas other subregions of body representation are actively involved, bilaterally, during the performance of a relatively simple motor behaviour.

Animals↗
PubMed1996

Visually guided reaching with the forelimb contralateral to a "blind" hemisphere in the monkey: contribution of the cerebellum.

Metabolic activity was mapped in the cerebellar cortex and its major inputs and projection targets in monkeys performing visually guided reaching with the left forelimb. Normal monkeys and monkeys deprived of visual input to the right cerebral hemisphere by right optic tract section, combined in some cases with forebrain commissurotomy, were studied. We reported previously that visually guided reaching with the left forelimb activated the motor cortex of the right hemisphere equally in all these monkeys, indicating that reaching was controlled by the right hemisphere whether it was visually intact or "blind" [Savaki H.E. et al. (1993) J. Neurosci. 13, 2772-2789]. In the present study, metabolic activations were observed in the left cerebellar hemispheric extensions of vermian lobules V, VI and VIII, again regardless of whether the right hemisphere was visually intact or "blind". In intact monkeys, however, the activations were significantly smaller in the lateral than in the paravermal zone of these hemispheric extensions, whereas in tractotomized/commissurotomized monkeys the activations were equal in the two zones. The greater activations in the left lateral zone in tractotomized/commissurotomized monkeys may represent compensation in part for the visual deafferentation of the right cerebral hemisphere. Also observed were metabolic activation in the left dorsolateral pontine nucleus in tractotomized/commissurotomized monkeys and metabolic depression in the left dentate nucleus in visually intact monkeys. This pattern of results suggests the following conclusions. The activated loci in the left cerebellar cortex combine (i) visual information about the target relayed by seeing cerebral hemispheres, and (ii) sensorimotor information concerning intended and actual movements of the left forelimb relayed by the right cerebral hemisphere and the limb, respectively, and then (iii) send this integrated information back to the motor cortex of the right cerebral hemisphere, thus enabling it to guide the left forelimb to the target whether the hemisphere is visually intact or "blind".

Animals↗
PubMedDate not supplied

Transition from fetal to adult repair occurring in mouse forelimbs maintained in organ culture.

In previous wound healing experiments with the use of midgestation murine fetal forelimb explants, wounds were made before or immediately after amputation from the fetus. This experimental technique allows one to ask the question: do circulatory elements initiate or sustain the repair process in vitro? The hypotheses tested in the current study were that repair occurs in organ culture in the absence of systemic influences and that the in vivo transition from fetal-like to adult-type repair persists in an unperfused in vitro system. Gestational day-14 mouse forelimbs were harvested and placed in serum-free culture medium. Before amputation, control forelimbs received linear full-incision microscalpel wounds that were closed primarily. The animals in the other group were not immediately wounded but cultured for 4 days and then wounded with primary wound closure. All limbs were cultured for 7 days after wounding and then processed for histologic analysis. In the immediately wounded limbs, scarless healing occurred with collagen fibers deposited in a reticular form. In contrast, the delay-wounded limbs had collagen organized in parallel arrays (disordered), constituting repair by scarring. Wound repair proceeded as a local phenomenon in the absence of systemic mediators. We conclude that day-14 gestation forelimbs undergo maturation in culture, causing a transition from scarless to adult scar repair.

Journal Article↗