Decreases in the response latency to priming over the first year of life

We previously reported that the latency of responding to a memory prime in a reactivation procedure decreases between 3 and 6 months of age. The present study extended this analysis through the first year of life. In this study, 6-, 9-, and 12-month-olds learned an operant task. One week after they had forgotten it, infants were exposed to a component of the original event as a memory prime and were tested after different delays for evidence of retention. Although the interval between the original event and priming increased linearly with age-from 3 weeks at 6 months to 9 weeks at 12 months, the latency of responding after priming decreased linearly with age-from 1 hr at 6 months to 0-1 s at 12 months. The latency of responding after priming was not task-specific; at 6 months, it was identical in two different tasks. These results provide additional evidence that priming in reactivation studies with infants is the same automatic, perceptual identification phenomenon as repetition priming in studies with adults.

Urea kinetic modeling: comparing the options

In this study 6 commercially produced kinetic modeling packages utilizing a variable volume, single pool urea model, as well as formulae to determine the delivery of therapy, have been compared by applying to each the same set of rigorously collected data for a group of 12 patients. Comparison of the kinetically derived parameters (urea generation rate [G], urea distribution volume [V], delivery of therapy [Kt/V], and normalized protein catabolic rate [nPCR]) showed that the values obtained for both G and V differed between packages owing to the numerical methods and the clearance used in the solution of the differential equations. Although a broad agreement between the values established for Kt/V and nPCR was noted, the 95% limits of agreement indicated that it would be prudent to exercise caution when comparing results established by different modeling packages.