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.