Cephalic sensory influence on forelimb movement in newborn opossums, Monodelphis domestica.

Like other marsupials, the opossum Monodelphis domestica is born very immature and crawls, unaided by the mother, from the urogenital opening to a nipple where it attaches and pursues its development. If the alternate, rhythmic movements of the forelimbs which allow this locomotion are generated by the developing spinal motor networks, sensory information is nonetheless needed to guide the newborn to a nipple. Behavioral, anatomical and physiological studies suggest that the auditory and the visual systems are insufficiently developed in newborn opossums to influence spinal motor centers, while the vestibular, trigeminal, and olfactory systems are likelier candidates.