Cerebral Cortex Of Animals Research Articles

Glutamic acid decar☐ylase activity decreases in mouse neocortex after lesions of the basal forebrain

Glutamic acid decar☐ylase (GAD) activity was measured in the cerebral cortex of animals after acute and chronic lesions to basal forebrain cholinergic nuclei. Such lesions were shown to result in an extensive depletion of cholinergic markers in parietal cerebral cortex. A statistically significant 30% decrease in GAD activity was first detected at 6 weeks postlesion and was still measurable 8 months after the lesion. These results suggest that cholinergic inputs to cortex indirectly or directly influence GABAergic transmission in cortex.

Plasma and brain cholecystokinin levels in cancer anorexia.

The syndrome of cancer anorexia includes early satiety in man and a reduction in the duration of feeding in experimental animals. These aberrations suggest dysfunction of peripheral and/or central nervous system satiety mechanisms in tumor-bearing individuals. Since the gut peptide, cholecystokinin (CCK), has been implicated as a potent satiety cue in man and animals, plasma and brain concentrations of CCK were measured by radioimmunoassay in anorectic tumor-bearing rats. Plasma concentrations of immunoreactive CCK were not significantly altered in either an acute Walker 256 carcinosarcoma or more chronic methylcholanthrene-induced sarcoma animal model of cancer anorexia. However, levels of immunoreactive CCK were significantly reduced in the hypothalamus and cerebral cortex of animals bearing the methylcholanthrene sarcoma during both mild and severe anorexia. These data demonstrate that elevations in immunoreactive CCK are not a major factor in the etiology of cancer anorexia. If brain CCK is involved in satiety, tumor-bearing rats may be attempting to compensate for their anorexia by down-regulating CCK production.

Regional difference in cyclic AMP response to adenosine of rat cerebral cortex with an iron-induced epileptic focus.

A chronic epileptic focus not resulting in generalized convulsions was induced by a microinjection of FeCl3 solution into the left anterior cortex of rats. Cyclic AMP accumulation in response to adenosine was examined in incubated slices from the cerebral cortex of animals that showed bilateral spike and slow wave complex in an electrocorticogram (ECoG) 30 to 60 days after the microinjection. Cyclic AMP accumulation after incubation with adenosine was most marked in slices from the left anterior quadrant of the cortex including a FeCl3-injected site. A medium response was observed in both the left posterior and the right anterior quadrants, but little or no response in the right posterior quadrant of the cortex.

New methods to determine the CNS effects of antigeriatric compounds: EEG topography and glucose use

AbstractBuchsbaum, M.S., J. Cappelletti, R. Coppola, F. Regal, A. C. King, and D. P. van Kammen: New methods to determine the CNS effects of antigeriatric compounds: EEG topography and glucose use. Drug Dev. Res. 2:489–496, 1982.It has previously been possible to measure regional glucose use in the cerebral cortex in animals only with autoradiographic techniques. With the advent of position emission tomography (PET) using (18F‐2DG) 18F‐2‐deoxyglucose, it is now possible to assess local glucose uptake in μmol/100 g tissue/min in normal volunteers or patients. The PET technique is complex and costly and cannot be repeated frequently because of the radiation dosage. However, local glucose use is closely tied to cerebral blood flow, and studies have related blood flow to EEG frequency measures. In this study, we have simultaneously investigated local glucose metabolism using 18F‐2DG with PET and EEG frequency with 16‐lead topographic mapping in six normal controls. Subjects sat in an acoustically treated darkened room with eyes closed for 10 min prior to, and 30 min following injection of 3–5 mCi 18F‐2DG. Following uptake, seven to eight horizontal scans parallel to the canthomeatal line were made. EEG recordings are made beginning 1 min after injection of the isotope and continuing for 30 min with 12 standard 10/20 system points on the left hemisphere and midline, and 4 additional points between existing posterior leads. Ten‐second EEG epochs are edited for artifacts and then analyzed by fast Fourier transform techniques. Using a cross‐sectional whole‐head atlas, a standardized, approximately equal‐area two‐dimensional representation of a lateral view of the brain was developed and 10/20 system scalp coordinates were projected onto it. EEG power estimates are interpolated for all points on this brain map. Using digital techniques, a 1‐cm‐thick cortical strip is peeled off each PET, slice and conformed to the lateral brain view, and values between strips are interpolated. The result is two simultaneously obtained electrophysiologic and metabolic lateral views of brain function displayed in gray‐scale values represented by dot density. In some subjects with eyes closed, alpha power is high in low glucose‐use regions, such as the occiput. Temporal regions appear low both in glucose use and in most power bands. Parallels between alpha distribution and glucose use are illustrated.

Histochemical and morphological evaluation of cerebral cortex of new-bornrat in the course of joint ethanol and pyrazole administration

The object of the study was the cerebral cortex of newborn rat. Tissue material was collected from the 2-nd to the 8-th hour after birth both from control animals and newborns whose mothers had been given both ethanol and pyrazole throughout gestation period, and also either ethanol alone or pyrazole. The drug were administered by gastric tube, in doses: ethanol 8.0 g/kg body weight, pyrazole 36 mg/kg body weight. Histochemical studies revealed variation in the intensity of reaction of the respiratory enzymes during examination of the cortex of newborns whose mothers had been fed with ethanol alone, or pyrazole alone. A strong inhibition of enzymatic reaction was observed in the examined cerebral cortex of newborns after a joint ethanol and pyrazole administration. Morphological studies showed an inhibition of maturing process of the cerebral cortex cells of animals treated with ethanol alone, whereas the cerebral cortex of animals whose mothers had been given both ethanol and pyrazole, presented symptoms allowing to diagnose encephalitis congenita symptomatica.

A TECHNIQUE FOR DIFFERENTIAL PHOTOELECTRIC PLETHYSMOGRAPHY OF BRAIN AND EAR.

A technique for implantation and apparatus for obtaining a circulatory pulse volume wave from the surface of the cerebral cortex of animals in both acute and chronic experimental situations are described. Fiber optic light guides are placed through burr holes on the brain surface and the skull closed with cement, thus restoring the Munro-Kellie principle. Heatless light is conducted into the brain and changes in optical density of this tissue due to vascular pulsation are converted to wave forms by a photoelectric pickup. Trauma and tissue reaction are minimal. Attachment of a similar plethysmograph to the ear by means of Teflon button receptacles allows differential recording of plethysmograms from either vascular bed. fiber optics; photoelectric technique; Munro-Kellie principle Submitted on March 5, 1964

The ontogenetic development of steady potential differences in the cerebral cortex in animals

Steady potential differences of cerebral cortex in rats and guinea-pigs were measured during ontogenesis and the possibility of eliciting a spreading depression by topical application of KC1 to the cortical surface in animals of various ages was studied. Cortical steady potential was measured using four different methods: 1. 1. Potential difference between the sciatic nerve and cerebral cortex. 2. 2. Potential difference between a damaged cortical area and normal cortical surface (cortical injury potential). 3. 3. Terminal depolarisation — negative potential shift developing in cerebral cortex during the 20 min. after total circulatory arrest. 4. 4. Potential difference between normal cortical surface and a cortical area damaged 20 min. after death. The cortical surface of adult rats is 19–20 mV. positive against other electricaly indifferent areas. This positive potential mainly develops during the first 20 days of life in rats, being 2.6 mV. in rats aged 5 and 14.0 mV. in rats aged 20 days. Only after the age of 15 days it is possible to elicit spreading depression by topical application of 1 per cent KCl in rats. The slow potential change accompanying the wave of EEG depression is smaller in amplitude and more prolonged in duration in the 15 day old rats than in adult animals. Guinea-pigs on the contrary display definite cortical polarisation from just after birth. New-born guinea-pigs generally respond by a spreading depression to topical application of 1 per cent KCl to the cortical surface. The values of cortical polarisation in different age groups are compared with other data concerning the morphogenetic and functional development of the brain in rats.

ORIGIN OF THE THEORY OF CONDITIONED REFLEXES

THE TERM was introduced by Pavlov in 1903. He mentioned it for the first time in an oration entitled Experimental Psychology and Psychopathology in Animals, which he delivered at the International Congress of Medicine in Madrid in April of that year.1 By a conditioned reflex Pavlov meant a response, established in an animal, to one or more unessential properties of a stimulating object. These properties, the sight or smell of food, for example, act through the appropriate receptive surface—the eye or the nose in this case—while the main receptive surface which is of concern here (the mucous membrane of the mouth cavity) remains unaffected. The conditioned response requires the participation of the central nervous system, especially that of the cerebral cortex, which may be considered the chief organ of conditioned reflexes. After the removal of the cerebral cortex in animals, only crude conditioned reflexes can be established,