Timing Information Provided by Trial-Stimulus Onset and Offset in a Sign-Tracking Procedure

Abstract

Four types of stimulus-food contingencies were compared for effectiveness in producing and maintaining trial-stimulus pecking in pigeons. The four trial-stimulus contingencies were: (a) fixed-length trials contiguous with food, (b) variable-length trials contiguous with food, (c) fixed-length trials with fixed-length trace intervals preceding food, and (d) variable-length trials with variable-length trace intervals preceding food. In all cases the inter-trial interval was variable with a 30-sec. mean and the trial stimulus was 5 sec. or 5 sec. on the average. Trial-stimulus pecking was rapidly acquired when the trial stimulus was contiguous with food, whereas the trace procedures produced pecking in only a few pigeons and then only after considerable training. Neither variability in the trial-stimulus length nor in the trace interval reliably affected acquisition or maintenance.

The incentive amplifying effects of nicotine are reduced by selective and non-selective dopamine antagonists in rats

“…The CS is a spatio-temporal stimulus with a discrete meaning – at the end of the CS, a reward is always delivered. The temporal properties of the CS may be critical to the development of sign tracking, as previous studies have shown that inserting a trace between the CS and US delivery reduces sign-tracking (Christian et al, 1983). Mesotelencephalic DA systems have frequently been implicated in timing behavior, as mice with deletions of the gene that encodes the DA transporter display poor temporal control of behavior in operant timing tasks (Meck et al, 2012) and the firing of DA neurons in the VTA shifts from ‘surprising’ rewards to CSs that temporally disambiguate reward delivery (Schultz et al, 1997, Schultz, 1998b, a).…”

“…Although more research is needed to investigate this hypothesis, the temporal features of sign-stimuli have been basically ignored in the recent resurgence of sign-tracking studies (cf. Christian et al, 1983). Nevertheless, the goal-tracking response is also time-locked to the presentation of the CS, with the critical difference being the target of the conditioned approach.…”