highly significantP<0.0001
When all observations of Xe effects on freezing at PR-LTM1 were pooled from these two independent experiments (Air-exposure, n = 20; Xe-exposure, n = 21) there was a highly significant reduction in freezing both to context alone ( t 39 = 4.63, P<0.0001) and context + tone ( t 39 = 2.16, P<0.01) compared to air-exposed controls.