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

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 +/- 0.02 degrees C). When the posterior hypothalamus temperature was increased or decreased (by 0.5-1.5 degrees C), changes in the initial interspike-interval distributions were observed in 11 neurons. The changes disappeared when the thermal stimuli were removed; 6 neurons (of 11) altered the mean firing rates too when the posterior hypothalamus temperature was changed.