Digital measurement of operant disk press force maintained in CD-1, BALB/c, and C57BL/6 mice

Force of disk press responses by inbred (C57BL/6 and BALB/c) and outbred (C D-1) mice were measured with a PC/DOS-based system, which allowed for conti nuous measurement of pressing, as well as for control of reinforcer present ation on the basis of response-force dimensions. Photobeam-based measuremen t of mouse entry into a hopper where reinforcers were presented provided ad ditional information about anticipatory and consumatory behavior in relatio n to environmental stimuli leading up to reinforcer delivery Disk pressing was generated and measured with the use of an analog-to-digital interface w ith all three mouse strains. The strains differed in the physical and tempo ral characteristics of the disk press, as well as in the behavioral chain l eading to reinforcer presentation. These measurement methods appear well su ited for quantitating functional behavioral differences occasioned by genet ic variations in mice.