The temporal pattern of responding in conditioned bar-press suppression: The role of the context switch and training mode

The present study examined the temporal pattern of responding in a conditioned bar-press suppression task in rats. Rats were exposed to either a 30-s or a 120-s conditioned stimulus (CS) followed by a footshock. Training took place either while the rats were lever-pressing for water (online), or with the lever removed from the box (offline). They were then exposed to the CS while they were lever-pressing for water, either in the training context or in a different context. Bar-press suppression during the CS was constant across the duration of the CS during training, but was restricted to the initial portion of the CS at the time of testing, especially when subjects were tested in a different context. Those results replicate the reactive (as opposed to anticipatory) pattern observed in a lick suppression procedure by Jozefowiez et al. (2011) and indicate that a change in context at the time of testing might be critical for its expression.

► Rats were exposed to a conditioned bar-press suppression.
► Three variables were manipulated: (1) the CS duration (30 s vs. 120 s), (b) the mode of training (online vs. offline), (c) the testing context (training vs. nontraining context).
► Suppression in the 120-s group was a decreasing function of time in the CS when the animals were tested in the nontraining context.
► This clarifies some of the conditions necessary to obtain a reactive pattern of suppression in bar-press suppression previously reported by Jozefowiez et al. (2011).