[Effect of unilateral decortication on inhibitory interactions of the superior colliculus in the cat].
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Effect of decortication on striatal dopamine turnover.
In rat striatum, frontal decortication did not affect the basal and the haloperidol-induced increases in dopamine (DA) turnover and the elevation in DA and dihydroxyphenylacetic acid concentrations produced by systemic administration of L-Dopa. These findings fail to support a role for the corticostriatal afferents in modulation of dopamine synthesis and release by nigrostriatal neurons. They suggest that DA receptors presumably localized on presynaptic corticostriatal terminals do not mediate the acceleration of DA turnover induced by neuroleptics. Data also indicate that corticostriatal terminals do not represent a locus for decarboxylation of exogenous L-Dopa to DA in the striatum.
3,4-Dihydroxyphenylacetic Acid↗
Anomalous patterns of response learning and transfer in decorticate rats.
Behavioural flexibility in decorticate rats was examined by testing response transfer in an obstructed alleyway. In the first experiment, rats were trained to push a ball out of a cylindrical alleyway in order to gain access to the goal box. When this 'push' habit was prevented by blocking forward movement of the ball, decorticate rats were much quicker than sham-operated rats in successfully developing the novel clearance response of pulling the ball into the start box. Both groups were subsequently able to reverse effectively between responses. In a second experiment, sham-operated and decorticate rats were first shaped to pull the ball clear from the alleyway, and then required to adopt a push-type clearance response when movement of the ball towards the start box was prevented. Here, the decorticates showed difficulty both in learning to pull the ball out of the alley and in transferring to a push-type clearance response, but having transferred they coped well with subsequent reversals. This asymmetrical pattern of transfer results is not readily attributed to response preference and raises the possibility that, in some situations at least, decorticated animals may show greater behavioural flexibility than had previously been supposed.
Animals↗
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↗
Perinatal decortication impairs performance on an 8-arm radial maze task.
Two experiments evaluate the role of the neocortex in rodent spatial learning. In Experiment 1, perinatally decorticated rats and sham-operated controls began ten training sessions at day 200 on an 8-arm radial maze. Decorticated rats made more errors than controls, but showed improvement by the tenth session. In the second experiment, training was extended to determine whether decorticates could eventually match control performance levels if given sufficient training. Spontaneous activity levels were also recorded and compared to maze performance to investigate the relationship between poor performance on the radial maze and activity. More than half of the decorticates reached criterion performance. Decorticates had significantly elevated spontaneous activity levels when compared to controls, and the magnitude of this hyperactivity was related to performance deficits on the radial maze. These results suggest that with extended training decorticates can learn a spatial task. Performance deficits may reflect the hyperactive tendency of decorticates rather than a specific impairment of spatial learning abilities.
Animals↗
Changes in the levels of glutamate and related amino acids in the intact and decorticated rat neostriatum during various conditions associated with convulsions.
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2-Amino-5-phosphonovalerate↗
Swimming escape learning in rats with telencephalic lesions.
Experiments were conducted to determine whether rats having unilateral or bilateral ablation of either the neocortex or telencephalon can learn to escape from a tank of water by climbing a platform. Hemi- or bilaterally decorticated rats were able to learn the swimming escape task, the same being observed for hemidetelencephalated rats. Fully detelencephalated rats, however, did not exhibit this capability. These results show that integrity of one of the cerebral hemispheres is necessary in order to allow swimming escape learning.
Animals↗
Frontal decortication decreases the affinity of N-(1-[2-thienyl]cyclohexyl)[3H]piperidine binding to rat striatum.
Bilateral ablation or transection of the corticostriatal pathways of the rat caused a reduction in N-(1-[2-thienyl]cyclohexyl)[3H]piperidine ([3H]TCP) binding to the striatum at 5-7, but not 3 and 14-28, days postlesion with a persistent decrease in striatal glutamate content 3-28 days after the decortication. This reduction was found to be due to an increase in Kd without changes in Bmax of the [3H]TCP binding. The present findings suggest that interruption of striatal glutamatergic transmission following frontal decortication may produce a temporal reduction in the affinity of phencyclidine receptor in the striatum.
Animals↗
Visual fields of cats with cortical and tectal lesions.
When cats were tested for visual field perimetry, the field of vision for each eye separately was from 45 degrees contralateral to 90 degrees ipsilateral. After either bilateral occipitotemporal lesions (with a split of the tectal commissure) or bilateral area 17, 18, and 19 lesions, the cats could see with each eye only from the midline to 90 degrees ipsilateral. A cat that became nearly totally blind as a result of bilateral occipitotemporal decortication had a subsequent tectal split which enabled it to see with each eye from the midline to 90 degrees ipsilateral.
Animals↗
Mechanisms for binocular depth sensitivity along the vertical meridian of the visual field.
By removing the visual cortex unilaterally, and recording along the intact 17/18 border, we have investigated the influence of the corpus callosum on the tuning curves for stimulus disparity of cat cortical neurons. Responses to binocular stimulation were examined to movement in the same (in-phase) and in the opposite direction (antiphase) across the two retinae. In lesioned cats, as in normal cats, units were encountered which showed high sensitivity and narrow tuning for stimulus disparity. In contrast to normal cats, however, lesioned cats showed a reduced proportion of units displaying moderate binocular interactions, as well as a substantial increase in disparity-insensitive cells. The loss of disparity sensitivity after decortication was associated with a reduced incidence of both selectivity for the direction of stimulus motion and binocular activation. No large differences between the preparations were seen, however, in the ocular dominance of the total populations of cells. Differences between the normal and lesioned cats were found in binocular responses to in-phase but not to antiphase stimulation motion. Tuning curves in lesioned cats showed reduced binocular inhibition but no changes in binocular facilitation. Our findings indicate that callosal input contributes to unit disparity sensitivity by enhancing direction-selective binocular inhibition. The corpus callosum generates disparity sensitivity in a population of units in the superficial cortical layers which may play a particular role in the perception of stereoscopic depth.
Animals↗
Effects of cholecystokinin and vasoactive intestinal peptide on locomotion and rearing in neofrontal decorticated rats.
Cholecystokinin octapeptide (CCK-8) and vasoactive intestinal peptide (VIP) have been shown to be antagonistic in various parameters in the rat in our previous studies. In the present investigation the effects of CCK-8 and VIP on spontaneous motility and rearing activity were observed in sham-operated and neofrontal decorticated rats. The results indicate that VIP antagonizes the effects of CCK-8 on spontaneous motility and rearing, and the effects are more apparent in the decorticated rats. It was suggested that CCK-8 affects presynaptic dopaminergic systems, while VIP is likely to stimulate post-synaptic dopaminergic mechanisms.
Animals↗
Can male decorticate rats copulate?
Sexually experienced or naive male rats, subjected to neocortex removal or neocortex plus hippocampus removal, were paired with female rats for up to 180 days and compared with control rats with respect to success and latency to impregnate the female. All of the control rats and half of the brain-damaged rats successfully impregnated female rats at least once. Success was not correlated with lesion type or presurgical experience. The brain-damaged rats took longer to impregnate the females than control rats. Since the ablations were extensive, more than 95% of the neocortex in many rats, the study shows that decorticate rats can copulate. Presumably the intact subcortical structures are sufficient for male copulation, but cortical structures in some way facilitate rapid female impregnation.
Animals↗
Extracellular striatal dopamine and glutamate after decortication and kainate receptor stimulation, as measured by microdialysis.
Disruption of corticostriatal glutamate input in the striatum decreased significantly extracellular striatal glutamate and dopamine levels. Local administration of 300 microM concentration of excitatory receptor agonist kainic acid increased significantly extracellular striatal dopamine in intact freely moving rats. These findings support the hypothesis that glutamate exerts a tonic facilitatory effect on striatal dopamine release. The effect of kainic acid on extracellular striatal glutamate concentration in intact rats was a biphasic increase. The first glutamate increase can be explained by stimulation of presynaptic kainate receptors present on corticostriatal glutamatergic nerve terminals; the second increase is probably the result of a continuous interaction of the different striatal neurotransmitters after disturbance of their balance. Release of dopamine and glutamate was modulated differently in the intact striatum and in the striatum deprived of corticostriatal input. Dopamine release in the denervated striatum after kainate receptor stimulation was significantly lower than in intact striatum, confirming the so-called cooperativity between glutamate and kainic acid. Loss of presynaptic kainate receptors on the glutamatergic nerve terminals after decortication resulted in a loss of effect of kainic acid on glutamate release in denervated striatum. Aspartate showed no significant changes in this study.
Animals↗
Decortication is a valuable option for late empyema after collapse therapy.
BACKGROUND: Infection of previous collapse therapy spaces may raise challenging problems. This study evaluated a conservative surgical approach based on decortication. METHODS: Since 1979, 28 patients (mean age, 60 +/- 6 years) have presented at an average of 37 +/- 7 years after artificial pneumothorax for tuberculosis. Diagnosis of empyema was made on follow-up in 12 patients and on symptoms in 16 patients. Mean vital capacity was 66% +/- 16% of normal. Microorganisms were isolated in 13 patients (Aspergillus fumigatus in 5, Mycobacterium tuberculosis in 4, anaerobes in 4). Decortication was made in 24 patients, associated with thoracoplasty in 4, and with partial lung resection in 2 patients. Thoracoplasty alone was performed in 2 patients, and 2 patients underwent an extrapleural pneumonectomy. RESULTS: Both extrapleural pneumonectomies were complicated with empyema requiring thoracoplasty, resulting in one postoperative death. Operative mortality after decortication was nil. Mean intraoperative blood loss during decortication was 1,830 +/- 1,310 mL. All patients were extubated within 24 hours, except 1 patient who was ventilator-dependent preoperatively. Prolonged air leaks were common (mean duration of drainage, 16 +/- 11 days), but ultimately sealed. Existence of symptoms was predictive of prolonged air leaks (p < 0.01). CONCLUSIONS: We conclude that decortication may provide a one-stage cure avoiding the hazards of extrapleural pneumonectomy; the nonfunctioning remaining lung may resolve the space problem.
Aged↗
Retention of conditioned inhibition of the nictitating membrane response in decorticate rabbits.
Rabbits were trained on a Pavlovian conditioned inhibition (CI) task using light as the reinforced conditional stimulus (CS) and the same light compounded with a tone as the non-reinforced CS. The conditional response was the nictitating membrane response (NMR). The subjects then received an extensive neocortical lesion or a sham operation. After 9 weeks postoperative recovery, the animals were retrained on the CI task. Sham operated control animals showed immediate and high levels of CI retention but the decorticates showed a profound initial loss, showing that there is a cortical influence in CI. Reacquisition of CI by the decorticates was rapid and showed considerable savings over de novo acquisition. This supports our earlier finding that the neocortex is not essential for the acquisition of CI.
Animals↗
[The effect of total extirpation of the neocortex on reflex activity in rats].
Using motor-feeding methods, studies have been made of the effect of complete extirpation of the neocortex on formation of new or recovery of pre-formed differentiation of localization of sources of light of identical intensity. It was shown that decortication results in significant and mostly irreversible disturbances of unconditioned reflex activity. In decorticated rats, only the simplest forms of conditioned motor reaction were noted which exhibit dominant features. Conditioned reflex to illumination combined with feeding is not recovered and is not formed a new in its biologically perfect form.
Animals↗
Differential localization of the mRNAs for the pertussis toxin insensitive G-protein alpha sub-units Gq, G11, and Gz in the rat brain, and regulation of their expression after striatal deafferentation.
The corticostriatal pathway is among the largest glutamatergic pathways in the brain, and of particular interest to the study of glutamatergic transmission. The metabotropic glutamate receptors (mGluRs) couple the actions of glutamate to intracellular second messenger systems through G-proteins. The most prominent of the mGluRs present in the target of this pathway, the striatum, is mGluR5. The identity of the G-proteins mediating the actions of mGluR5 are unknown, but the receptor is linked to stimulation of phosphoinositide (PI) turnover and largely resistant to the effects of pertussis toxin, which inhibits some G-proteins. We used in situ hybridization to examine the expression and regulation of three pertussis toxin insensitive G-protein alpha sub-units: Gq, G11, and Gz. We found that these mRNAs are differentially distributed in the rat brain, but all three are expressed by striatal neurons. After glutamatergic deafferentation of the striatum by decortication, there is a modest upregulation of G11 mRNA, while expression of Gq and Gz are unchanged. Following dopaminergic deafferentation, expression of Gq, G11, and Gz are not altered, although expression of the pertussis-sensitive sub-unit Go is increased. Our data suggests that Gz, Gq, and G11 are each expressed by striatal neurons, and therefore may be involved in mediating the actions of mGluR5 in these cells. After decortication G11 is upregulated, but the magnitude of this effect is small, and alone seems insufficient to account for the marked biochemical supersensitivity of glutamate-stimulated PI turnover which is observed.
Afferent Pathways↗
Brain development in the neonatally decorticated rat.
The brain weights, cross-sectional areas of subcortical structures, gross morphology, and retrograde degeneration in the thalamus and basal ganglia were compared in rats with neonatal (1 or 5 days of age) or adult ablation of all of the neocortex. Neonatal decorticate and control rats also were given injections of fluorescent retrograde tracers. True blue or Nuclear yellow into the striatum, hippocampus, or subiculum in order to identify afferent pathways to these structures. Neonatal decortication resulted in morphological changes that included a dramatically shrunken and misshapen thalamus, a shrunken brainstem, distortion of the hippocampal structure and abnormal growth of the subiculum, none of which were observed following adult decortication. There was a complete absence of gliosis and calcification in the 1-day decorticates that was present in 5-day and adult decorticates. Although most striatal and hippocampal afferents from subcortical structures were present, label was not found in the ventral tegmental area or thalamus after True blue injections into the striatum and hippocampus, respectively. Acetylcholinesterase staining showed the normal striatal patchy organization. The absence of evidence for the development of new pathways or the reorganization of existing pathways is consistent with previous behavioral studies showing little sparing of function after neonatal decortication. The results suggest that the cortex plays little role in programming pattern formation and connections in subcortical structures and that cortical and subcortical structures provide unique contributions to the control of behavior.
Age Factors↗