QUANTITATIVE TRAIT LOCUS ANALYSIS OF CONTEXTUAL FEAR CONDITIONING IN MICE

Family, twin and adoption studies provide evidence for a Table I Mean scores for measures of learning substantial genetic component underlyi ng individual Altered Auditory differences in general intelligence(1), specific cognitive abilities(2) and susceptibility to psychopathologi es related to fear-inducing events(3). Contextual fear conditioning, w hich is highly conserved across species, can serve as a model for eluc idating genes that regulate individual differences in learning and emo tion(4-8). In fear conditioning, an initially neutral stimulus, such a s shock. Two neural circuits have been implicated in fear conditioning . The fear component is regulated by amyhdaloid pathways, while the co ntextual component is, at least in part, dependent on the hippocampus( 9-14). C57BL/6J (B6) and DBA/2J (D2) mice differ in several types of c omplex learning(15,16), including contextual fear conditioning(17). A quantitative trait locus (QTL) analysis of contextual fear conditionin g was performed in a B6/D2 FZ intercross population. Two QTLs for cont extual conditioning (led score>4.3) were identified on chromosomes 10 and 16. QTLs for conditioning to the auditory cue (led score>4.3) were localized to chromosomes 1 and 10. Suggestive QTLs (led score=2.8-4.1 ) for contextual conditioning were detected on chromosomes 1, 2 and 3.