Spontaneous and evoked hypothalamic unit activity in kittens during development.

Spontaneous and evoked hypothalamic unit activity in response to sensory stimuli was studied in acute experiments on anesthetized kittens. After the second day of postnatal development, spontaneous unit activity can be recorded in the posterior hypothalamus. Evoked responses to sciatic nerve stimulation were recorded on the fourth to fifth day after birth. In the early stages of development phasic and tonic types of unit responses are present in the hypothalamus, with some predominance of phasic. At the end of the third week responses of hypothalamic neurons in kittens have still not reached their definitive formation.