Predictors of nutritive sucking in preterm infants.

OBJECTIVE: The purposes of this analysis were to determine how select characteristics of nutritive sucking (number of sucks, sucks/burst, and sucks/minute) change over time and to examine the effect of select factors (morbidity, maturity, prefeeding behavior state, and feeding experience) on those changes. STUDY DESIGN: A longitudinal, non-experimental study was conducted in a Level 3 neonatal intensive care unit using a convenience sample of 88 preterm infants. Statistical analyses were performed using a repeated-measures mixed-model in SAS. RESULTS: Sucking activity (number of sucks, sucks/burst, and sucks/minute) was predicted by morbidity, maturity, feeding experience and prefeeding behavior state. Experience at oral feeding had the greatest effect on changes in the number of sucks, suck/burst and sucks/minute. CONCLUSION: Experience at feeding may result in more rapid maturation of sucking characteristics.

An integrated system for measuring static and dynamic accommodation with a Canon Autoref R-1 refractometer.

An integrated system is described which we have found useful for efficiently collecting and analyzing both static and dynamic accommodation data using the Canon Autoref R-1 refractometer. The system consists of hardware modifications and software designed to both facilitate the measurement of accommodation and to process the resulting data. Several features of the Canon R-1, which may not be evident to some users, are also described. A program written in Microsoft C/C++ running under DOS, and designed for use on a PC, is available from the authors upon request.

Preferences and asymmetries in saccadic responses to delayed bihemifield stimuli.

Saccaadic response preferences and latencies were measured using dual targets presented at 5, 10 and 15 deg along the horizontal meridian in either one or both visual hemifields. In the unihemifield condition, subjects exhibited a strong preference (about 95%) in favor of the target presented closer to the original fixation point. Further, the presence of the second target did not increase the response latency to the preferred target. In the bihemifield condition using spatially symmetric targets, directional preference varied across subjects from 57 to 100% (mean = 83%). There was also a significant increase in response latency as compared with responses to either single targets or dual targets presented in one hemifield. This latency increase was observed for responses in both the preferred and nonpreferred directions and was taken as evidence of mutual interaction between the two hemispheres. The response preferences could be eliminated by delaying the onset of the preferred target by about 100 msec in the unihemifield condition and by about 50 msec in the bihemifield condition. Further, the interactions between the effects of the targets on response time in the bihemifield condition were found to be asymmetrical in that a target presented in the preferred hemifield has a greater effect than a target in the nonpreferred hemifield on responses to targets presented in the counterhemifield. The results suggest an asymmetry in hemispheric interaction which has not previously been demonstrated in the visualoculomotor system.