The histoenzymic activity of gyrus cinguli in the course of postnatal ontogeny of the rat.

Histochemical investigations concerning the activity of several dehydrogenases and hydrolases in the area cinguli during postnatal ontogenic development of the rat were performed. Brain sections corresponding to the region of area cinguli, obtained from rats aged 1, 3, 8, 17, 40 and 60 days postnatal, were subjected to histochemical assays for various dehydrogenases, phosphatases and esterases. The developmental changes concerning histoenzymic reactivity of the callosal gyrus with regard to several respiratory and hydrolytic enzymes were assessed and described. Considerable differences in enzymic reactivity, appertaining particularly to the phosphatases and esterases, between the anterior and posterior parts of the callosal gyrus were found. The unusual enzymic reactivity of glial cells in the individual regions of the area cinguli has been pointed out.     

Effect of sensory stimulation on the lamina V pyramidal neurons of the gyrus cinguli in the rat

Three groups of Wistar-rats were exposed to permanent noise (80 db) during different periods in their postnatal life: the first group was exposed starting from birth for a period of four weeks, the second one from birth up to nine weeks of age and the third group from the fifth up to the ninth week postnatal. A fourth group (control animals) was reared under normal laboratory conditions. After the experiments the brains were exposed to a modified GOLGI-method. In lamina-V-pyramids of the gyrus cinguli lightmicroscopical results: length, number and distribution of spines on the main apical dendrites and on the apical dendritic branches where evaluated. Main results: 1. Permanent noise during the early postnatal development phase of the brain of rats (from birth up to the fourth week of age) causes a statistically significant increase of apical spines. The spines-values are 20% above those of the control animals. 2. Permanent noise from birth up to the ninth week of age or applied only during the later postnatal period (from the fifth week up to the ninth week of age) does not significantly alterate the spines-value. 3. The results are estimated as a consequence of extreme environmental factors causing effects, comparable with an universal stress reaction. Conclusions were discussed in comparison to the results of other authors.     

Motor alimentary conditioned reflexes and delayed reactions in dogs following destruction of the caudate nucleus]

The characteristics of formation and achievement of motor conditioned reactions were studied in seventeen dogs before and after the lesion of head or body of the caudate nucleus. It has been shown that the degree of higher nervous activity disturbances depends on the localization of injuries in the nucleus, and on the complexity of the tests used. The caudate nucleus exerts a modulating effect on the parameters of motor conditioned reflexes and takes a direct part in the structure of delayed reflexes. Lesion of the caudate nucleus body is attended with more serious disturbances of higher nervous activity than lesion of its head.     

Avoidance reactions to painful stimulation of another individual following destruction of the rat amygdala]

Experiments in male albino rats have shown that bilateral lesion of the amygdala does not prevent avoidance conditioning to pain stimulation of another rat, improvement of the reaction after a painful action of the experimental animal and its extinction after the discontinuation of pain stimulation of the partner. Amygdalectomy performed after elaboration of a conditioned avoidance reaction, improves or worsens it, depending on which of the two rivaling motivations (sensitivity to signals of the other animal or fear of an open field) relatively predominanted in the given animal before the operation. The facts obtained suggest that the amygdala may be classified as belonging to the system of brain structures, where the "interrupting function" of emotions is achieved directing the behaviour to meet the predominant need.     

Development of the brain stem reticular formation during ontogenesis of lower simians as compared with man]

The work has shown a number of common features in the structural organization of the brain stem reticular formation in the adult rhesus monkey and man. According to the peculiar features and developmental features the reticular nuclei may be divided into 3 sections (median, medial and lateral) having different genesis. In ontogenesis all the nuclei of the reticular formation undergo differentiation and specialization due to the complication of the brain as a whole. This process, however, goes differently in ontogenesis of the macaque and man which can be seen in the heterochronous rate of their development, namely, in the macaque the terms of maturation of the reticular nuclei are somewhat more accelerated. The work shows changes in the density of cells, the volume of neurones and all the reticular formation in relation to the volume of the brain stem as a whole. However, the differences found in ontogenesis of the macaque and man are mainly of quantitative and idioadaptive character.     

Cyanogenesis inhibits active defense reactions in plants

In the course of fungal attack on the cyanogenic rubber tree (Hevea brasiliensis Muell.-Arg.) HCN is liberated from infected tissue. The HCN interferes with plant host and fungal pathogen. It becomes inhibitory to active defense responses which are dependent on biosynthetic processes as far as a threshold concentration is transgressed.