[Changes in activity of the hypothalamic neurons in response to physiological fluctuations of the homeostasis constants].

In acute experiments on cats under the combined narcosis (ketamine + N2O) we have investigated impulse activity of the rostral hypothalamic neurons and analyzed its modifications due to visceral stimulation. As stimulation we used warmed up or cooled (on 7 degrees C) a paw of an animals, cooled a body of an animal, we administered solutions into a carotid artery: 5 % of glucose, 0,2 % and 3 % NaCl, phenilephrine. Thus we modeled fluctuation of homeostasis's constants in physiological limits in an animal organism. It is shown that the greatest quantity of investigated neurons--more than 10 % authentically changes a pattern impulse activity when we entered solutions of 5 % of glucose and 0,2 % NaCl into a carotid artery of animals. In other cases the degree of transformation of a pattern was less (6-7 %) and approximately identical. When we entered of a microdose phenilephrine into the v. femoralis in order to modulate press effect we registered minimal quantity of neurons (1,4%). Studing of the parameters of the IA hypothalamic neurons during the homeostatic changes could be a basis for finding of transformation of the functional state of neurons which take part in the regulator mechanisms for maintaining of homeostasis.

[Characteristics of the frontal hypothalamic neuron reactions to the electrical stimulation of the cerebral cortex in cats].

In acute experiments we have used the glass microelectrodes and registered outside cell's impulse activity of the cats' hypothalamic neurons. We used the serial stimulation during 5 s (with frequency impulse 12, 30, 100 s(-1)) to the hippocampus (zone CA3), pyriform, cingulated and proreal cortexes. We have compared the background impulse activity (in the bine) of the neurons with the impulse activity after the stimulation. Two types of the neuron' reactions in response to the cortical stimulations were defined, they consisted in the mean frequency changes to the impulse activity during stimulation and during period in 15-30 sec after completion the stimulation. It is shown that the most of hypothalamic neurons explored (and neurons of the preoptic region) have changed their impulse activity during period, which approached through 15-30 sec after completion the-high frequency (100 s(-1)) stimulation to the all cortical zones and the stimulation of hippocampwith frequency 30 s(-1). We supposed that the cortical stimulations have a significant effect on the impulse activity pattern of the rostral hypothalamic neurons

[A new method of analysis of impulse activity in brain neurons]. / Novyi metod analizu impul'snoï aktyvnosti neironiv mozku.

Investigation of impulse activity of hypothalamic neurons is of a great importance in attempt to connect the neuronal function with its activity. We have proposed an original method of analysis of background and temperature-induced impulse activity of thermosensitive neurons from frontal hypothalamus. In acute experiments on cats under ketamine anastasia neuronal activity was measured by glass microelectrode. Measurements of background neuronal activity was performed during 30 s, and post-stimulus activity was measured during 60 s. Computer program calculated the mean value of background activity. These results were used to create bar graph in the range +/- 100% with time interval 10%. It is suggested that the results of analysis of background activity of thermosensitive hypothalamic neurons allow interpret the characteristics of functions of hypothalamic neurons.

[Pneumo-automatic apparatus for the artificial ventilation of the lungs for small laboratory animals]. / Aparat shtuchnoï ventyliatsiï lehen' na pnevmoelementakh dlia dribnykh laboratornykh tvaryn.

We have designed apparatus of artificial ventilation of the lungs (AAV) for small laboratory animals on pneumoelements, examined static and dynamic characteristics of a generator of impulse signals and chose rational parametres of the apparatus. Some advantages of that model as compared with its analogues have been proved. The apparatus was approved at electrophysiological experiments on rats, 200-250 g. Monitoring of the most important parameters of the vital functions showed that external breathing on that apparatus was adequate.

[Convergence studies of hypothalamic neurons]. / Doslidzhennia konverhentsiï hipotalamichnykh neironiv.

In this study has been reveibed the peculiarities of convergence of afferent cortical inputs to the hypothalamic neurons. Single and the serial stimulation of phylogenetically distinct cortical areas (proreal cortex (field 8), cingular cortex (field 24), pyriform lobule (periamygdala cortex), and hippocampus (CA3) were used. We have established two main focuses of expressed convergence of signals from the above mentioned cortical areas. First of them was located in the lateral hypothalamus nucleus, second--in the centromedial hypothalamus nucleus. Single cortical stimulation was found to excite majority of hypothalamus neurons. Expressed prevalence of inhibitory responses over excitatory ones were found in case of serial stimulation application. This functional organisation of the hypothalamic nucleus allow to propose tonic character of the cortical influences due to serial stimulation and the eventual character of these influences due to single stimulation.

[The characteristics of the background neuronal activity of the rostral hypothalamus and an analysis of its alteration under the influence of the stimulation of phylogenetically heterogeneous sections of the cerebral cortex]. / Kharakterystyka fonovoï aktyvnosti neironiv rostral'noho hipotalamusa ta analiz ïï zminy pid vplyvom podraznen' filohenetychno heterohennykh viddiliv kory holovnoho mozku.

In acute experiments on cats under mixed narcosis (ketamine + N2O) we have investigated background firing activity of the rostral hypothalamic neurons and analyzed it modifications due to serial stimulation (100 imp/s, during 5 s) of the prefrontal, cingulate, pyriform cortices and hippocampus. Analysis of the ongoing mean frequency histograms allowed to single out three types of background firing activity with different rhythmical properties. Three types of interspike intervals distribution i.e. asymmetrical (A), symmetrical (S) and polymodal (P) have been distinguished as well. Cortical stimulation was found to transform types of interspike intervals distribution in 15% of hypothalamic neurons. S-type changed into P-type and A-type--into P-type. Author discussed correlation between the character of background firing activity, types of interspike intervals distribution and functional properties of hypothalamic neurons.