[Temperature dependence of neuronal activity in hypothalamic and hippocampal slices of the guinea-pig]. / Zavisimost' aktivnosti neironov ot temperatury v srezakh gipotalamusa i gippokampa morskoi svinki.

Unit activity in slices of the hippocampus and medial preoptic area of the hypothalamus of guinea-pigs was extracellularly recorded under conditions of temperature changes. Seven out of nineteen hypothalamic neurons showed changes in the firing rate at threshold temperatures of 36-38 degrees C. In the suprathreshold range the activity of these neurons depended on the temperature level. It is suggested that such neurons may form a sensory part of the system controlling brain temperature within a narrow (1-2 degrees C) range. The pyramidal layer cells of the control structure (hippocampus) were insensitive to the temperature level within 32-40 degrees C.

[Intrahypothalamic connections of the lateral hypothalamus]. / Vnutrigipotalamicheskie sviazi lateral'nogo gipotalamusa.

Using the axon degeneration method by R. Fink and L. Heimer, organization of intrathalamic connections between various areas of the lateral hypothalamus have been studied after unisided electrolitic lesion. At any location of the injury foci, similar patterns are observed in ipsilateral distribution of degenerating fibers along the whole lateral preoptico-hypothalamic area. The most massive degeneration is observed in the zone where the medial forebrain bundle (MFB) fibers run. The degenerating fibers spread forward--into the septal area, and backward--into the mesencephalic part of the brain. The rostral and caudal parts of the lateral hypothalamus, taking part in formation of the MFB collateralies towards the thalamus, are connected with various thalamic nuclei. Massive preterminal degeneration in the perifornical zone and single argerophile granules in the medial hypothalamus convincingly demonstrate an important role of the intermediate zone for connections of its medial and lateral parts with each other. The conclusion that the intrahypothalamic connections of the lateral hypothalamus are realized within the MFB system supports the modern notion on a close connection of the lateral hypothalamus with the system of longitudinal diffuse bundles of fibers of the medial anterocerebral pathway that run through it.

[Neuronal organization of the thermosensory region of the anterior hypothalamus]. / O neironal'noi organizatsii termosensornoi oblasti perednego gipotalamusa

In anesthetized rabbits, extracellular recording of activity of 236 neurons was made in the anterior hypothalamus on changing of its temperature (+/-3 degrees C). 27% of the neurons revealed high sensitivity to the temperature stimulus with coefficient Q10 from 2.4 to 30; 6% of the neurons reacted by the on-response type; 5% of the neurons changed their activity and preserved the new level. The character of the unit responses seems to indicate that the anterior hypothalamus fulfills not only the reception of temperature shifts, i.e. the primary processing of information, but its further analysis as well.

[The effect of leukocyte pyrogen on thermosensitive neurons of the anterior hypothalamus]. / Vliianie leikotsitarnogo pirogena na termochuvstvitel'nye neirony perednego gipotalamusa

Impulse activity of neurons of the medial preoptic and septal brain areas of rabbits caused by variations in the local temperature and systemic injections of the leukocytic and bacterial pyrogens was studied. The firing rate of the warmsensitive neurons decreased and that of the cold thermodetectors was activated as a result of pyrogen action. As compared with the bacterial pyrogen, leukocytic pyrogen caused a more rapid decrease of the warmthermodetector activity. Thermoneutral neurons failed to react considerably either to the leukocytic or to the bacterial pyrogen.