Offspring Behavioral Development Research Articles

Transgenerational plasticity of exploratory behavior and a hidden cost of mismatched risk environments between parental sexes

We require a better understanding of the relative contribution of different modes of non-genetic inheritance in behavioral trait development. Thus, we investigate variation in exploratory behavior, which is ecologically relevant and a target of selection. The metabolic hypothesis predicts exploratory behavior to be size-dependent across taxa. This size-dependency is cancelled out under high perceived risk, allowing us to determine the transgenerationally integrated estimated level of risk. Using fathead minnows Pimephales promelas, we manipulated perceived risk in mothers, fathers, caring males and offspring through continuous exposure to either conspecific alarm cues or to a control water treatment. In 1000 four-month old offspring, we determined body sizes and exploratory behavior. Perceived high risk in mothers, followed by personal risk, was most effective in eliminating size-dependent behavior whereas effects of paternal risk on offspring behavioral development were substantially weaker. When maternal risk is high, environmental mismatches between parents prevented offspring from responding appropriately to personal high risk. The environment of the caring male also impacted offspring behavior to a greater extent than that of its genetic parents. Our study highlights the high relative importance of maternal, personal and caring male risk environments and showcases potential costs of an environmental mismatch between parental sexes.

Brief and long periods of maternal separation affect maternal behavior and offspring behavioral development in C57BL/6 mice

For rats, maternal mediation of brief and longer term dam-pup separations were thought to account for pup differences in adult "emotionality." In this study, early handling (EH), maternal separation (MS), and maternal peer separation (MPS) groups were compared to an animal facility reared (AFR) group for maternal behavior and offspring adult open-field behavior in C57BL/6 mice. Although MS and MPS dams displayed higher levels of maternal behavior upon reunion, these group differences did not predict offspring open-field behavior. However, when offspring behavior was analyzed as a function of specific aspects of maternal behavior, irrespective of treatment group, pups that received high levels of quiescent nursing and activity, but not licking, were less "emotional." Individual differences in maternal licking of pups predicted variability of "emotional" behavior for AFR and EH pups. Thus, for this strain of mouse, individual and not treatment differences in maternal care predict offspring "emotional" development.

Paternal behavior influences development of aggression and vasopressin expression in male California mouse offspring

Parental care has been demonstrated to have important effects on offspring behavioral development. California mice ( Peromyscus californicus) are biparental, and correlational evidence suggests that pup retrieving by fathers has important effects on the development of aggressive behavior and extra-hypothalamic vasopressin systems. We tested whether retrievals affected these systems by manipulating paternal retrieval behavior between day 15 and 21 postpartum. Licking and grooming behavior affect behavioral development in rats, so we also experimentally reduced huddling and grooming behavior by castrating a subset of fathers. Experimentally increasing the frequency of paternal pup retrieving behavior decreased attack latency in resident–intruder in both male and female adult offspring, whereas experimental reduction of huddling and grooming had no effect. In a separate group of male offspring, we examined vasopressin immunoreactivity (AVP-ir) in two regions of the posterior bed nucleus of the stria terminalis (BNST): the dorsal fiber tracts (dBNST) and the ventral cell body-containing region (vBNST). Experimentally increasing retrievals led to an apparent shift in AVP-ir distribution. Specifically, offspring from the high retrieval group had more AVP-ir than offspring from the sham retrieval group in the dBNST, whereas the opposite was observed in the vBNST. Experimental reduction of paternal grooming was associated with increased AVP-ir in the paraventricular nucleus and also increased corticosterone and progesterone, similar to observed effects of maternal grooming on HPA function. This study provides further evidence that paternal behavior influences the development of aggression and associated neural substrates.