Effects of prematurity and early intervention on responsivity to tactual stimuli: a comparison of preterm and full-term infants.

Cardiac and behavioral responses to a tactual stimulus were evaluated during the first sleep cycle for 3 groups of infants: 30 full terms, 30 nonintervened preterms, and 30 intervened preterms. Prior to testing, the latter group had received a regimen of multimodal sensory stimulation, which emphasized the tactual and vestibular modalities. The results showed that the intervention altered the preterms' sensory functioning mainly during active sleep. In this state, the full terms and the intervened preterms exhibited a significant cardiac acceleration to the stimulus, while the nonintervened preterms failed to do so. Similarly, the behavioral response of the intervened preterm more closely approximated that of the full terms. During quiet sleep the intervention did not affect either the cardiac or the behavioral response. In this sleep state, the full terms' cardiac response was that of monophasic acceleration, whereas both groups of preterms exhibited a biphasic response with a smaller initial acceleration which was followed by a deceleration below baseline. Behaviorally, the preterms responded less frequently and gave smaller responses than the full terms. Thus there were marked differences between preterms and full terms, and the intervention seemed to narrow this gap to some extent.