LeDoux Lab 2010 SfN Abstracts

Program#/Poster#:	914.18/MMM34
Title:	Enduring effects of early life trauma on fear reactivity in the adolescent rat
Location:	Halls B-H
Presentation Time:	Wednesday, Nov 17, 2010, 2:00 PM - 3:00 PM
Authors:	*A. PICKENHAGEN1,2, C. RAINEKI1,2,3, C. K. CAIN1,4, J. E. LEDOUX1,4, R. M. SULLIVAN1,2,3,4; 1Emotional Brain Inst., Nathan Kline Insititute, Orangeburg, NY; 2Child and Adolescent Psychiatry, NYU Sch. of Med., New York, NY; 3Dept. of Zoology, Univ. of Oklahoma, Norman, OK; 4Ctr. for Neural Sci., New York Univ., New York, NY
Abstract:	Individual differences in response to fearful events have only scarcely been studied. The majority of animal research investigating the neural basis of fear has focused on typical responses, thereby potentially omitting relevant information concerning individual variability. Recently, a study examined such individual differences with regards to fear reactivity in the adult rat, using the paradigm of fear conditioning and found individual differences to be stable (Bush et al., 2007). A priori behavioral markers of these high/low fear reactivity phenotypes have however not been identified. Infant trauma is a key environmental factor influencing the later development of psychiatric disorders. In our lab, we have shown that different models of early life trauma in infant rats result in aversive consequences later in life (Sullivan et al., 2000). It is thus possible that infant trauma may also affect later fear reactivity. In the present study, we investigated whether individual differences identified in adult rats were already present during adolescence and if so, whether it is possible to identify a priori behavioral markers of high/low fear reactivity. To this purpose, pups were either reared (from postnatal day 8 to 12) with a mother that handled her pups roughly (induced by insufficient bedding for nest building) or with a control mother with normal maternal behavior. All animals were subsequently allowed to grow up in identical conditions and underwent odor-0.7mA shock fear conditioning and extinction paradigms at different time points during adolescence. Our results indicate that just as in adulthood, individual differences in fear reactivity are stable, and thus suggest that already in adolescence they can be indicative of trait-like attributes. Additionally, we observed that abused rats showed reduced freezing in response to the cue presentation when compared to rats reared with a normal mother throughout infancy. In accordance, abused rats also spent more time in the light compartment of the light/dark box. Combined these results suggest a less anxious/fearful phenotype in the abused rat and hint towards increased impulsivity during adolescence. Understanding the mechanisms underlying individual differences in fear as well as the identification of early life predictors of such differences can provide us with insights into fear disorders in humans and allow us to have an early life indicator of later adolescent/adult phenotype.
Support:	NIH Grant DC009910 NSF 10F-0850527