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The retention and extinction of a conditioned taste aversion after either short (6-day) or long (60-day) intervals was investigated in preweanling (I8-day-old) and adult rats. Taste-only and illness-only control conditions were employed, as were variations in the concentration of the US (holding Liel amount constant). Results indicated that after the short retention interval, retention of the taste aversion was equivalent for both ages. After the long interval, however, the I8-day-old rats exhibited significantly weaker taste aversion than their adult counterpartsinfantile amnesia. Manipulation of US concentration had no effect on the magnitude of the taste aversions for either age or retention interval. The results are discussed in terms of their implications for infantile amnesia and general laws of learning.Immature animals forget at a faster rate than do more mature animals (for reviews, see Campbell & Campbell & Spear, 1972;Spear, 1978Spear, , 1979, and this probably is also true for humans (Cohen & Gelber, 1975;Levy, 1960;Pancratz & Cohen, 1970). This accelerated rate of forgetting by younger organisms has been termed infantile amnesia. However, some recent evidence suggests that less infantile amnesia may occur when the information to be retained involves a particular class of events that may constitute a "highly prepared" association (Coulter, Collier, & Campbell, 1976;Spear, 1978). Ontogenetic studies of conditioned taste aversion (Campbell & Alberts, 1979; Klein, Mikulka, Domato, & Hallstead, 1976) provide some of the more convincing of this evidence.While long-term retention of taste-illness associations by adults is excellent (Biederman, Milgram, Heighington, Stockman, & O'Neil, 1974;Dragoin, Hughes, Devine, & Bentley, 1973), the data with respect to immature organisms are mixed. Specifically, Klein et al. (1976), using postweanling rats (23-dayold), and Campbell and Alberts (1979), who used preweanling (18-day-old) infant rats, have demonstrated retention equivalent to that of adults over retention intervals of 28 and 56 days. However, with rat pups 10 and 12 days of age, Campbell and Alberts (1979) did find poorer retention across long intervals. Both of these studies used LiCI as the unconditioned stimulus (US) and employed a singlebottle testing procedure. The data obtained with Preparation of this article was supported by grants from the National Science Foundation (BNS 74-24194 and BNS 78-02360) to the third author. We thank Norman "Richter for technical advice and assistance and Teri Tanenhaus for preparation of the manuscript. Requests for reprints should be sent to Norman E. Spear, Department of Psychology, State University of New York at Binghamton, Binghamton, New York 13901. these procedures suggest that, by 18 days of age, rat pups have attained adult levels of retention for a taste-illness association. In contrast to the findings of Campbell and Alberts (1979), Ader and Peck (1977) and Peck (Note 1) have reported relatively poor retention of all early (Zl-day-old rat pup) taste-ill...

Atrazine technical was evaluated for its embryotoxic, fetotoxic, and teratogenic potential in both rats and rabbits. The compound was orally administered at doses of 0, 10, 70, or 700 mg/kg.d to groups of rats on gestational d 6-15, while rabbits were administered doses of 0, 1, 5, or 75 mg/kg.d on gestational d 7-19. Maternal toxicity was observed at doses greater than or equal to 70 mg/kg.d in rats and at doses greater than or equal to 5 mg/kg.d in rabbits. Minor fetal effects, concurrent with maternal toxicity, were observed in rats at doses greater than or equal to 70 mg/kg.d. Among rabbits, fetal effects concurrent with severe maternal toxicity were only observed at the 75 mg/kg.d dose level. There were no adverse maternal or fetal effects in either rats or rabbits at the low dose levels. These findings indicated that pregnant rabbits were more sensitive than pregnant rats to the effects produced by atrazine technical and the compound was not teratogenic at maternally toxic dose levels in either species.

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Although methanol (MEOH) may assume a significant role as a fuel, which implies wide availability, little is known of its toxicity apart from acute poisoning episodes in human adults. Even less is known about its toxicity in developing organisms. This experiment studied the early behavioral development of rats whose mothers had consumed MEOH during gestation by measuring the responses of suckling (postnatal day 1) and nest-seeking (postnatal day 10). Primigravida Long-Evans rats were divided into three groups (N = 10). Two of the groups consumed drinking solutions of 2% MEOH instead of distilled water either on gestational days 15-17 (MEOH 1) or 17-19 (MEOH 2). No maternal toxicity was apparent as measured by weight gain, gestational duration, and daily fluid intake. Daily MEOH consumption averaged 2.5 gm/kg over the 3-day period in both MEOH groups. Litter size, birth weight, and infant mortality did not differ among the three groups. Postnatal growth and date of eye opening were unaffected. MEOH pups required longer than controls to begin suckling on postnatal day 1. On postnatal day 10, they required more time to locate nesting material from their home cages. These data suggest that prenatal MEOH exposure induces behavioral abnormalities early in life that are unaccompanied by overt toxicity.