Male mice of each strain (6-10 weeks) were placed into
standard-size mouse shoebox cages covered with clear Plexiglas
(instead of a normal wire top, to prevent hanging). Cages were placed inside the photobeam
field of a Columbus Instruments Opto-Varimex Micro Animal Activity System
for a 4 hour period. Eight mice were tested simultaneously in
individual cages with or without a saline injection, counterbalanced
among strain as much as possible. The mean horizontal+vertical
(rearing) beam breaks in 4 hours are reported for each strain.
Mice were tested in light (1200h to 0400h) and dark (2000h to 2400h) periods.