[The initiation of cold shivering during the local heating of the rat hypothalamus under immersion hypothermia].

A local artificial heating of the hypothalamic centre of thermoregulation in rats subjected to immersion cooling to a deep hypothermia activated a shivering. The data obtained suggest that one of the reasons of disorders in the organism thermoregulatory functions under conditions of a deep hypothermia involves a direct effect of the cold upon the thermoregulation centre in the hypothalamus.

[The neuronal reaction of the rabbit thalamus to thermal stimulation of the skin].

Skin temperature of the rabbit back and face was increased to 38-40 degrees C or decreased to 22-26 degrees C. Out of 48 units under study 10 neurons responded to the cold skin stimulation, the latency of the responses varying from 10 to 50 s. The thalamic neurons responded also to the light, sound and mechanical stimuli.

[The "thermoresponsive" neurons of the thermoregulation center and their functional characteristics].

The specific features of responses to thermal stimulation of the skin in neurons of the thermoregulation centre in the anterior and posterior hypothalamus were investigated in rabbits. Separate neurons were found to respond to temperature changes like skin thermoreceptors. A part of thermal signals from the skin is supposed to arrive to the thermoregulation centre without specific transformation.

[Heat transfer by the blood in the venous vessels of the rabbit under different temperature conditions].

The blood temperature in the main venous vessels reflects the formation of the heat balance in the body. In the rabbit posterior vena cava, the temperature increased by 0.19 degrees C-0.

[The neuronal impulse activity of the thermoregulation center under the conditions in a thermoneutral zone].

In thermoneutral ambient temperature, posterior hypothalamic neurons were found whose firing rate oscillations were associated with the hypothalamus and skin temperature fluctuations in unanesthetized rabbits. These neurons seem to take part in the thermoregulation function.

[Temperature differences between the arterial and venous blood in the major vessels of the rabbit].

In unanesthetized rabbits, arterial (abdominal artery) and venous (v. posterior cava) temperatures were recorded. The arterio-venous temperature differences attained: 0.

[The physiologic and physical patterns of blood heat exchange with tissues and the environment].

The temperature of arterial blood flowing to the ear and of venous blood outflowing from the latter was measured initially and under heat load in anesthetized rabbits. The partial calorimeter yielded the values of heat production from the ear (in cal/min). Heating of the animal increased the blood flow and the heat production (4- and 5-fold, resp.

[Determination of the neuronal reactions of the thermoregulation center in the posterior hypothalamus of the rabbit to thermal stimulation].

Impulse activity of the posterior hypothalamic neurons was investigated under conditions of thermoneutral environment and at thermal skin stimulation of unanesthetized rabbits. Different types of the activity were classified. The responses of neurons to thermal stimulation were followed by changes in the activity types.

[Convergence of signals on neurons of the anterior hypothalamus during local thermal stimulation of the skin].

Changes in the mean firing rates of the preoptic and septal neurons under thermal stimulation of different skin areas were studied in unanesthetized rabbits. The skin temperature of the rabbit back (skin area I) or face (skin area II) was increased to 38-40 degrees C or decreased to 22-26 degrees C. Out of 111 units under study 21 units responded to changes in the skin temperature.

[Statistical study of the impulse activity of posterior hypothalamic neurons in the presence of local changes in its temperature].

Distribution of the intervals between spikes of 50 neurons in the posterior hypothalamus were studied in 17 unanesthetized rabbits. Three main types of the interspike-interval distribution were found in the thermoneutral zone: 1) unimodal, mode 2-4 ms; 2) unimodal, mode 16-512 ms; 3) bimodal, modes 2-10 ms and 64-512 ms (the posterior hypothalamus temperature was 39.1 +/- 0.

[Effect of a change in the temperature of the midbrain and skin on the activity of posterior hypothalamic neurons].

Changes of the mean firing rate of neurons in the posterior hypothalamus on a regional increase or decrease in the midbrain temperature (0.6-2.0 degrees C) and skin temperature (3-5 degrees C) were studied in unanesthetized rabbits.

[Interaction of central and peripheral temperature signals on the thermosensitive neurons of the hypothalamus].

Changes in the mean firing rate of neurons in the posterior hypothalamus were studied in unanesthetized rabbits at the local increase in the brain temperature (0.7-1.5 C) and at an increase in the skin temperature (3-5 degrees C).