Modulation of the thalamocortical responses of the sensorimotor cortex during stimulation of the lateral hypothalamus in rabbits in ontogeny

It has been demonstrated that rhythmic stimulation of the relay thalamic nucleus in rabbits at the second half of the first month of postnatal life does not significantly affect the amplitude of the second and third positive components (PC-2 and PC-3) of the positive phase of the thalamocortical responses. Combination of rhythmic stimulation of this nucleus and that of lateral hypothalamic structures is accompanied by a significant increase of the amplitude of both positive components of the thalamocortical responses, the degree of potentiation of PC-3 being higher than that of PC-2. The described potentiation is most evident at the third week of postnatal development of rabbits.     

Modulation of pyramidal response in the rat sensorimotor cortex after combined stimulation of the lateral hypothalamus and the sensorimotor cortex

It was shown during experiments on unrestrained rats that rhythmic stimulation of the pyramidal tract produced a statistically significant increase in the functional activity of neuronal populations of the sensorimotor cortex, manifesting as potentiation of the primary, positive phase of pyramidal cortical response. Combined rhythmically matched stimulation of the pyramidal tract and of the lateral hypothalamus leads to statistically significant enhancement in potentiation of the positive phase of pyramidal cortical response compared with effects produced independently of hypothalamic involvement. When stimulation of the pyramidal tract and the lateral hypothalamus are combined with stimulation applied at the same periodicity to the sensorimotor cortex, a further statistically significant enhancement in potentiation of the positive phase of pyramidal cortical response is seen in addition to the potentiating effect produced by hypothalamic stimulation.Institute for Brain Research of the All-Union Scientific Center of Mental Health, Academy of Medical Sciences of the USSR, Moscow. Translated from Neirofiziologiya, Vol. 18, No. 3, pp. 367–373, May–June, 1986.     

GABA metabolism and the formation of a sensorimotor cortex evoked potential in the presence of excess zinc ions

Changes in GABA content, the enzymatic activity of its metabolism and the formation of sensorimotor cortical evoked potential (EP) were studied following long-term ZnCl2 administration. It has been established that a single ZnCl2 injection at a dose of 0.1 and 1 mg/kg was accompanied by an increase in the amplitude of sensorimotor cortical EP, though GABA accumulation in this brain structure was observed. This might account for the prolongation of the period of the potential appearance. Long-term (for 7, 14, 21 days) ZnCl2 administration at a dose of 0.1 mg/kg produced a sharp depression in the potential appearance and an increase in GABA content by 50% with the enhancement of glutamate decarboxylase activity and the attenuation of GABA-transaminase activity.     

Inhibition, by electro-acupuncture, of the scalp evoked potential induced by painful stimulation of the tooth in man]

Scalp potentials evoked by electrical stimulation of the tooth pulp can be diminished in amplitude by electroacupuncture. This diminution goes generally in inverse with the increase in subjective pain threshold.     

Structural/functional disturbances in the rat sensorimotor cortex evoked by low-intensity environmental factors

The effect of low-frequency continuous vabration, hypokinesia, and shielding from the geomagnetic field were studied on 424 albino mongrel male rats. The action of these low-intensity factors of a different nature caused changes first of all in the microcirculatory bed (MCB) of the cerebral cortex. Structural disturbances, as well as the disturbances of redox metabolism in the neurons appeared close to those observed during hypoxia of a different origin; they obviously resulted from the disturbances of the MCB functions, which caused discrepancy between the needs for energy supply and the transport system state. Specificities of the disturbances evoked by different factors can be related to desynchronization of the biorhythms (e.g., caused by deprivation of the geomagnetic field).     

Changes in the cerebellar cortex of rabbits subjected to an electrical current on the posterior hypothalamus

After 3, 15 and 30 sessions of electrical stimulation of the hypothalamus by means of stereotaxically implanted bipolar electrodes into the area hypothalamica posterior, in the cortex of the cerebellar hemispheres, predominantly in the ganglionic layer, certain reactive, as well as poorly and intensively manifested pathological changes develop in neural and glial cells. Mosaicism of Purkinje's cells lesions within the layer, the state of their cytoplasmic matrix, granular endoplasmic reticulum and mitochondria, essential shifts in activity of oxidation-reduction enzymes at a simultaneous disorder in blood circulation and decreased content of catecholamines in the neural structures of the cerebellar vessels make it possible to estimate the process as centrogenic and neurodistrophic.     

Changes in the ultrastructure of the adrenal medulla and cortex during endotoxic shock

Electron microscopy of the adrenal medulla and cortex during the intermediate period of endotoxin shock has revealed severe destructive changes in parenchymal cells. These changes are the reason for synthetic, secretory and trophic disturbances of glandular functions. Ultrastructural lesions indicate that stress exposure exceeds the adaptive capacity of cells, the majority of which are exhausted and killed.     

Atherosclerosis in rabbits induced by prolonged electrical stimulation of the hypothalamus]

The influence of prolonged electrical stimulation of rabbit hypothalamus on blood lipids and the development of atherosclerosis were studied. The negative emotional state observed during the electrical stimulation was accompanied by blood hyperlipemia and atherosclerosis development in 1/3 noncastrated and 2/3 castrated animals.