Multiple units in brain stem and forebrain during the first week of life in the rat

Abstract

Multiple unit activity was recorded in newborn, 5-day old and adult unanesthetized and succinylcholine-immobilized rats. The development of neuronal responsiveness of mesencephalic reticular formation and basal fore-brain area was studied to various sensory modalities. It was found that both neuronal populations responded to acoustic and visual stimulation by a significant increase in the frequency of amplitude discriminated discharges as early as the first week of life. Somatosensory stimulation elicited a strong activation of both brain regions in new born rats, and this type of responsiveness decreased during development. It was proposed that the neonatal CNS is capable of processing sensory information. The high level of somatosensory responsiveness is of great importance in the survival of the newborn animal, possibly because this is the neuronal mechanism underlying elementary learning processes and memory formation.