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PubMed1990

Effects of treatment with microencapsulated monosialoganglioside GM1 on cortical and striatal acetylcholine release in rats with cortical devascularizing lesions.

The present study shows a novel administration form of the monoganglioside GM1, which following microencapsulation in human serum albumin was topically applied on cortical regions damaged by devascularization in rats. The effects of microencapsulated GM1 on extracellular levels of acetylcholine, choline and dopamine in the cortex and in the striatum were analyzed using in vivo microdialysis. Cholinergic neurons in the nucleus basalis magnocellularis were studied immunohistochemically using monoclonal antibodies raised against choline acetyltransferase (ChAT). It was found that cortical devascularizing lesions produced a decrease in extracellular levels of cortical acetylcholine and choline, and retrograde morphological changes in cholinergic neurons in the nucleus basalis magnocellularis. GM1 promoted (1) recovery of the retrograde morphological changes produced by the decortication in the nucleus basalis magnocellularis and (2) a parallel increase in cortical acetylcholine release. No changes were observed in the striatum, nor on cortical or striatal dopamine levels simultaneously measured in the same perfusates.

Acetylcholine↗
PubMed1974

Monocularly deprived cats: improvement of the deprived eye's vision by visual decortication.

Monocularly deprived cats were tested for visual perinetry before and after visual cortex lesions. Such a lesion greatly enhances the deprived eye's performance and impairs that of the nondeprived eye so that the pronounced preoperative interocular asymmetry is lost postoperatively. Apparently this destruction of abnormal corticotectal pathways allows the expression of previously suppressed, normal retinotectal pathways.

Animals↗
PubMed1981

Performance of decorticated rats in a two-choice visual discrimination apparatus.

Normal rats and rats with 98.8% (S.D. +/- 1.4) of neocortex surgically removed were trained in a two-choice discrimination apparatus for food reward. The animals were first trained to run the apparatus with identical non-patterned goal box doors followed by discrimination and reversal training using horizontal and vertical striped panels attached to the doors. These patterned stimuli were matched for total luminous flux and contour length and control procedures were included for unintended discriminative cues from other sensory modalities. The two groups did not differ in the number of trials taken to complete preliminary training but the decorticates were significantly faster at running the apparatus than the normals. All animals solved the visual discrimination and were able to reverse it. There were no significant differences between the groups in trials taken to acquire the visual discrimination except at the very highest criterion levels employed, though reversal of the discrimination was more difficult for the lesioned group. The preliminary training data are taken as further evidence that total decortication does not necessarily impair instrumental performance for food reward and that this lesion does not introduce any limiting sensory or motor deficit in the alleyway situation. It would also appear that neocortex is not essential for the solution of a horizontal/vertical stripe problem. It is not clear, however, that such a solution necessarily depends on a true pattern discrimination, and both lesioned and normal animals may have been employing strategies based on local cues within the two patterned stimuli. The appropriateness of the total decorticate preparation for a resolution of the problem of cortical vs subcortical substrates of residual vision following visual cortex lesions is discussed. The possibility that undamaged neocortical tissue remaining after visual cortex lesions may inhibit the full expression of residual subcortical function is raised by these data.

Animals↗
PubMed1977

Hypoxic ventilatory response of cats at high altitude: an interpretation of 'blunting'.

Cats acclimatized to a simulated altitude of 5500 m developed attenuated ventilatory response in the hypoxic test range of PAO2 = 60-45 torr, but their CO2 response remained normal, although the curve was shifted to a lower PACO2 range. The acclimatized cats a high respiratory frequency and maintained hyperventilation under normoxia. Cats from 3100 m altitude had hypoxic reponses which were, on the average, slightly below sea level standards, but the difference was not statistically significant. Two cats raised at 4640 m had a normal hypoxic ventilatory response even though the frequency response was 'blunted'. These data suggest the possibility of hypoxic 'threshold' near 5500 m to produce an attenuation effect. Another series of cats acclimatized to 5500 m were tested with more severe hypoxia, and they exhibited brisk ventilatory response in range PAO2, 40-25 torr, although they showed typical 'blunting' in the range PAO2, 60-45 torr. These results suggested that the phenomenon of attenuated hypoxic response at high altitude was a reflection of shift of hypoxic set point to a lower PAO2. Finally, it was shown that the hypoxic responses of 'blunted' animals were restored to normal after mid-collicular decerebration; and that decortication resulted in a typical hyperexcitability of the hypoxic response. These results are discussed in terms of hypothesized suprapontine modulating influences on the control of breathing, and possiblities for a contribution of these mechanisms in pathogenesis of hypoxic 'blunting' are raised.

Acclimatization↗
PubMed1986

Effect of serotonergic, corticostriatal and kainic acid lesions on the dopaminergic neurotoxicity of 1-methyl-4-phenyl-1,2,5,6-tetrahydropyridine (MPTP) in mice.

In mice, prior destruction of striatal 5-hydroxytryptamine (5-HT) neurons by intrastriatal or intraventricular injections of 5,7-dihydroxytryptamine did not abolish or attenuate DA depletions produced in striatum by 1-methyl-4-phenyl-1,2,5,6-tetrahydropyridine (MPTP). This suggests that although they contain monoamine oxidase type B, the oxidative conversion of MPTP to 1-methyl-4-phenyl-pyridinium ion (MPP+) does not take place in 5-HT neurons. Likewise, decortication and kainic acid lesions did not prevent or enhance striatal MPTP-induced DA decrements suggesting that corticostriatal projections and striatal neurons are not involved in the mechanisms of MPTP neurotoxicity.

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine↗
PubMedDate not supplied

[The vegetative component of a conditioned reflex].

Defensive and alimentary conditioned reflexes were studied on normal cats and cats with neural isolation of the neocortex. The cardiac component of the conditioned reflexes is elaborated in decorticated animals at a similar rate and is as steady as in normal cats. Motor conditioned reactions in decorticated cats are difficult to elaborate. Both in normal and decorticated cats unconditioned pain stimulation evokes tachycardia, while a conditioned signal, paired with this unconditioned stimulus, produces bradicardia. Ban assumption has been made that the primary conditioned reaction consists in the appearance of a certain emotional state which changes the cardiac rhythm in a typical way.

Animals↗
PubMed2001

The role of group I and group II metabotropic glutamate receptors in modulation of striatal NMDA and quinolinic acid toxicity.

Excitotoxic lesions of the striatum are mediated by the combined activity of N-methyl-d-aspartate (NMDA) receptors and metabotropic glutamate receptors (mGluRs). Intrastriatal injection of the NMDA receptor agonists NMDA or quinolinic acid creates large lesions, but in rats that have been decorticated to remove endogenous glutamatergic input, NMDA and quinolinic acid are no longer toxic. We report that NMDA toxicity can be restored in decorticated animals by coinjection of the group I mGluR agonists t-ACPD, t-ADA, or CHPG. In addition, injections of two group I mGluR antagonists, AIDA and (S)-4C3HPG, can protect against striatal lesions produced by quinolinic acid or NMDA injections in normal rats by blocking activation of group I mGluRs. The group II mGluR agonist APDC fails to protect against quinolinic acid or NMDA toxicity in intact animals or to restore NMDA toxicity in decorticated animals, suggesting that the role of group II receptors in this excitotoxic model is minimal. These observations confirm the important role of group I mGluRs in excitotoxicity and identify these receptors as promising targets for therapeutic intervention in neurodegenerative disease processes.

Animals↗
PubMed1984

Trace conditioning of the nictitating membrane response in decorticate rabbits.

Rabbits with substantial neocortical lesions were given trace conditioning of the nictitating membrane response over a range of interstimulus intervals (ISIs). Unlike hippocampal lesioned animals, which show deficits in such conditioning, the decorticates were not impaired and they gave greater numbers of conditioned responses at longer ISIs than did sham-operated controls. These results suggest that a neocortical-entorhinal input to the hippocampus may not be crucial for trace conditioning.

Animals↗
PubMedDate not supplied

Recovery of function after brain damage: the extrinsic stimulus specificity of spared neural traces.

Previous research has demonstrated that while primary visual cortex lesions in rats will disrupt performance of a learned brightness discrimination, the neural traces associated with this discrimination are spared. Moreover, the spared neural traces may, in certain instances, influence the postoperative reinstatement of a brightness discrimination. The present research was designed to determine the generality of this postoperative influence. The results indicate that while the normal rat and the visual decorticate rat may readily transfer learning between discriminations involving different discriminative cues, a visual lesion between two discriminations prevents this transfer. These data are interpreted as indicating that the postoperative influence of a spared neural trace is dependent upon the reoccurrence of specific extrinsic stimulus cues.

Animals↗
PubMed1977

The neurological basis of motor asymmetry following unilateral 6-hydroxydopamine brain lesions in the rat: the effect of motor decortication.

The role of the motor cortex in the mediation of asymmetric movement after unilateral 6-hydroxydopamine (6-OHDA) brain lesions has been examined in the rat. The effect of unilateral and bilateral sensorimotor decortication upon spontaneous and drug (apomorphine and amphetamine)-induced motor asymmetry has been studied following unilateral injection of 6-OHDA into the lateral hypothalamus. Both bilateral decortication and unilateral decortication on the side of the 6-OHDA lesion caused a transient reversal of the spontaneous motor asymmetry normally seen in 6-OHDA lesioned animals. Neither unilateral nor bilateral sensorimotor decortication abolished drug-induced turning behaviour. It is postulated that subcortical basal ganglia efferent pathways may be involved in the mediation of motor asymmetry after unilateral 6-OHDA lesions of the nigrostriatal dopaminergic projection.

Amphetamine↗
PubMed1985

The mating movements of male decorticate rats: evidence for subcortically generated movements by the male but regulation of approaches by the female.

The study shows that although many features of copulation in decorticate male rats are normal, copulatory success is importantly dependent upon the control of approaches exerted by the normal female rat. Copulation by neonatally decorticated adult rats and normal adult rats was studied in cohabitation and videotaped tests. Seven of 10 decorticate rats and 6 of 6 normal rats sired pups in the cohabitation test. When initially paired with ovariectomized and primed female rats, in the videotaped tests, all normal rats, but only one decorticated rat, copulated. All decorticate rats made movements indicative of sexual interest including: treading on the female's back, passing over the female, and sniffing the female's genitals. After activating stimulation, 5 of 6 remaining decorticated males copulated. After one successful mount the remaining copulatory patterns proceeded relatively normally. Numbers of mounts, intromissions, ejaculations, postejaculatory songs, and the intromission and ejaculatory patterns were like those of control rats, although the decorticate rats had fewer mount bouts and showed abnormalities in the execution of movements. Precopulatory movements were notated, using the Eshkol-Wachmann system, and compared with copulatory movements. Non-copulatory and copulatory approaches were similar, except that clasping appeared to be the key movement involved in the transition of an approach movement into a copulatory movement. The analysis also showed that the females' movements of hopping, turning, and kicking were important for regulating the males' approaches, and were instrumental in the success achieved by the decorticated males. The study shows that although the cortex, insofar as it facilitates the appearance of certain movements and contributes to their efficiency, is involved in male sexual activity, in its absence well organized sexual activity is possible, although this is dependent, in part, upon the behaviour of the female.

Animals↗
PubMed1977

Ventilatory response of decorticate and decerebrate cats to hypoxia and CO2.

The steady state ventilatory response of normal, fully awake cats was studied under graded hypoxia (at PAO2 = 110, 55, 45 torr) with PACO2 controlled throughout at the resting, normoxic level and at +5 torr. Subsequently, either a mid-collicular decerebration or a decortication was performed, and the ventilatory studies were repeated. Respiratory frequency, tidal volume, and ventilation in the decerebrate state responded to hypoxia and hypercapnia in a manner indistinguishable from the control. The decorticate cats, however, exhibited an exaggerated response to hypoxia, principally the result of increased frequency. The negative hypoxic, hypercapnic interaction, characteristic of awake cats, was demonstrable in both the decerebrate and decorticate animals. The findings are interpreted as revealing coupled descending influences on the medullary respiratory centers in hypoxia--one that is facilitatory and originates in the diencephalon, and the other, inhibitory, from the cerebrum. The significance of this suprapontine system in normal hypoxic ventilatory control is discussed.

Animals↗
PubMed1987

Increase in glutamate sensitivity of subthalamic nucleus neurons following bilateral decortication: a microiontophoretic study in the rat.

Responses of subthalamic neurons (STN) to the iontophoretic application of glutamate (Glu), acetylcholine (ACh) and GABA were studied in rats 2 or 3 weeks following bilateral decortication, and were compared to those obtained in normal animals. All the cells recorded in lesioned rats showed a decrease in their spontaneous firing rate. They also proved to be significantly more sensitive to the excitatory action of Glu, although their responsiveness to ACh or GABA was not modified.

Acetylcholine↗
PubMed1988

Striatal and cortical acetylcholine release in vivo in rats with unilateral decortication: effects of treatment with monosialoganglioside GM1.

Striatal and cortical extracellular acetylcholine (ACh) and choline (Ch) levels were determined in samples collected under in vivo conditions using microdialysis in normal (naive) and decorticated rats treated with saline or the monoganglioside GM1. ACh and Ch were assayed using a sensitive high performance liquid chromatography technique coupled to a postcolumn reactor with immobilized enzymes. Picomole amounts of ACh could be measured in the presence of an acetylcholinesterase inhibitor (neostigmine) in the microdialysis perfusion medium (striatal ACh = 0.2-0.4 microM; cortical ACh = 0.03-0.04 microM). Ch was detected both in the presence and in the absence of neostigmine (striatal Ch = 0.5-0.6 microM; cortical Ch = 0.6-2 microM). ACh, but not Ch, was strongly stimulated by 100 mM of KCl included in the perfusion medium. Decortication produced by devascularization did not significantly modify the cortical or striatal basal levels of ACh. However, in the cortex, KCl produced a higher ACh stimulation in the GM1-treated than in the saline-treated decorticated or naive rats. The present results indicate that GM1-treatment increases the ability of cortical cholinergic terminals to release ACh and support the idea that trophic factors such as monoganglioside GM1 can promote recovery following injuries of the central nervous system.

Acetylcholine↗
PubMed2004

Experience and cortical control over the pubertal transition to rougher play fighting in rats.

With the onset of puberty, play fighting in rats decreases in frequency and the tactics of attack and defense that are used are rougher. Previous studies have shown that the changes in the frequency of play and in the use of defensive tactics arise independently of social experience. Furthermore, while the former involves subcortical regulation, the latter depends on cortical mechanisms. In this study, the possible mechanisms regulating the developmental changes in the tactics of attack were examined. Two experiments were conducted using male rats. In the first study, rats reared in isolation from weaning were compared to rats reared in pairs, and were tested in the juvenile and early post-pubertal phases (30 and 60 days postnatally). In the second experiment, rats with their cortex removed shortly after birth were compared to sham-treated controls, and were tested in pairs at both the juvenile and early adult phases (30 and 90 days). Two measures of 'roughness,' derived from previous studies, were measured. Results showed that isolation-reared rats had the typical age-related changes in roughness of attack, whereas decorticated rats failed to show this age-related modulation, maintaining, or even exaggerating, the juvenile-typical pattern of attack. These findings suggest that social experience is not needed for this developmental change to occur, and that an intact cortex is needed to regulate this change in behavior.

Aggression↗
PubMed1976

[Effective of surgical decortication on cardio-cardiac reflexes in cats].

The cardio-cardiac reflexes were studied in unanesthetized curarized cats before and after surgical decortication. The data obtained showed three varieties of the cortical adaptation: the inhibition of the reflexes, their facilitation, and the effects of regulatory "silence". Under normal condition the cortical function seems to exert modulating influences on the cardio-cardiac reflexes by way of the afferent vagal nucleus.

Animals↗
PubMed1988

Evidence for central entrainment of the medullary respiratory pattern by the locomotor pattern in the rabbit.

1) Although periodic passive hindlimb movements can reproduce the enhancement of breathing frequency seen at the onset of muscular exercise, we have shown previously that they were unable to induce the 1:1 coupling which is observed between locomotion and respiration during galloping in quadrupeds. The purpose of this study was to investigate the existence of a central coupling in two experimental situations: first, decorticate - DOPA, and secondly, decerebrate rabbit preparations. 2) After DOPA administration in curarized, vagotomized, decorticate animals, an absolute coordination could be observed between the locomotor bursts (which developed in hindlimb muscle nerves) and phrenic activity. With the temporal evolution of the pharmacological activation, the coupling mode varied from 1:1 to 1:2 during the same experiment with a loss of coordination between these two forms. When the coordination between both motor activities was not produced in such conditions, it could be induced for some imposed frequencies of periodic passive motions applied to the contralateral hindlimb. 3) When the DOPA effects were completely over, a rostro-pontine decerebration allowed locomotor activity to be released and a tight 1:1 coupling could be obtained again between the two motor patterns in this new experimental situation. 4) An analysis of the data revealed that the various forms of coordination obtained in the different experimental situations are due to a central resetting of the respiratory and of the locomotor patterns. The capability of the hindlimb proprioceptive inputs to coordinate locomotor and respiratory patterns in the decorticate-DOPA preparation appeared simply linked to their ability to entrain the activity of the lumbar locomotion generator. It is suggested that these central reciprocal interactions, which have the properties of an entrainment process, are the result of interactions between the lumbar locomotion generator and the medullary respiratory one.

Action Potentials↗