Rats' behavior during an interfood clock is altered by the temporal pattern of interfood stimuli

Rats exposed to a basic interfood clock (a sequence of four different 12-s lights) during a 48-s interfood interval (IFI) showed a characteristic dist ribution of behavior: responses near the feeder peaked after food presentat ions, locomotion away from the feeder peaked in the middle of the IFI, and nosing in the feeder peaked just before food. Rats (Group Shorter) receivin g interfood stimuli that got progressively shorter (24 s-12 s-8 s-4 a-food) showed sharper increases in nosing in the feeder across the last half of t he IFI than rats (Group Longer) receiving interfood stimuli that got progre ssively longer (4 s-8 s-12 s-24 s-food). Although locomotion away from the feeder increased in the middle of the IFI for Group Shorter, activity in fr ont of the feeder increased at the beginning of the IFI for Group Longer. O verall, the data support a behavior systems view that motivational modes un derlying IFI behavior have timing characteristics that fit better with some temporal patterns of interfood stimuli than with others. Specifically, a s equence of progressively longer duration cues controls increased activity n ear the feeder at the beginning of the IFI, but a sequence of progressively shorter duration cues facilitates locomotion in the middle of the IFI and feeder-related responses at the end of the IFI. (C) 1999 Academic Press.