The results of the study reported in Brain Research in 1995 by Isaacson et
al. [Isaacson, R.L., Varner, J.A., Baars, J.-M., de Wied, D., 1995. The eff
ects of pregnenolone sulfate and ethylestrenol on retention of a passive av
oidance task. Brain Res. 689, 79-84] have been re-examined with special emp
hasis placed on the distributions of latencies found in the passive avoidan
ce task using rats. This study used two retention tests, one 24 h after tra
ining the other at 48 h after training. In the first experiment in that stu
dy a range of doses of two anabolic steroids, pregnenolone sulfate and ethy
lestrenol, were given s.c. just after the footshock training trial. In expe
riment 2 a similar range of doses of both steroids was given to the rats 1
h before the first retention test. Placing emphasis on the distributions ra
ther than measures of central tendencies revealed that, in contrast to the
vehicle treated animals, the anabolic steroid treated animals exhibited bim
odal distributions of response latencies. These differences between control
and hormone treated animals were observed in both experiments. The new inf
ormation was interpreted in terms of non-linear dynamics including some asp
ects of Chaos theory. (C) 2000 Elsevier Science B.V. All rights reserved.