and P line-scores formed a separate cluster on factor 2. Given that the HAD-LAD replicate pairs were generated from the same N/Nih foundation stock and the AA-ANA as well as P-NP lines had Wistar lines as their foundation stock, this is not entirely surprising. In another study, Overstreet et al. (1997a) reported that whereas HAD’s differed significantly from LAD’s (the replicate pair was not identified) on open field rearing, this measure did not differentiate P’s from NP’s nor did it differentiate AA’s from ANA’s. In another study examining anxiety-like behavior (Knapp et al., 1997), it was reported that total ultrasonic vocalizations (USVs) differentiated P from NP and AA from ANA rats. However, these authors (Knapp et al., 1997) also reported that time spent vocalizing differentiated P from NP, but not AA from ANA, rats. Contrarily, latency to emit USVs, after an air puff, differentiated AA from ANA, but not P from NP, rats.
