Abstract
Bioelectric activities of hypothalamic dendrites of newborn kittens and adult cats were recorded in vivo. Stimulation of various hypothalamic areas with electrical stimuli, or by injection of norepinephrine, generated propagated spikes in both new‐born and adult neurons. The morphologically immature hypothalamic dendrites were hypersensitive to stimuli and were able to generate propagated spikes not only of axon hillock (adults) but also of dendritic membrane origin. Some mechanisms responsible for the two types of spike formation (newborn and adult) have been identified.