The importance of touch in development.

Developmental delay is common in children deprived of normal sensory stimulation - for example, in premature neonates and some institutionalized children. Touch has emerged as an important modality for the facilitation of growth and development; positive effects of supplemental mechanosensory stimulation have been demonstrated in a wide range of organisms, from worm larvae to rat pups to human infants. Animal models are being used to elucidate the cellular and molecular mechanisms underlying these effects. In rats, the amount of maternal licking received as a pup has a profound impact on the behaviour and physiology of the adult; in the microscopic roundworm Caenorhabditis elegans, physical interactions with other worms promote growth and increase adult responsiveness to mechanosensory stimuli. By understanding the underlying mechanisms, as well as the timing and degree of stimulation required to fully reverse the effects of early childhood deprivation, strategies can be developed to best help those in need.