On a methodological level, we suggest that self-generated as compared to cue-induced expectations allow for a higher amount of experimental control in many experimental designs on expectation effects.
Furthermore spatial learners trained on days 6 10 or 11 15 show greater activation of new neurons compared to cue-trained rats during a probe trial 5 days after training.
Differentiating these two types of expectations for different contents of expectation such as stimuli, responses, task sets and conflict level, we review evidence suggesting that self-generated expectations lead to larger facilitating effects and conflict effects on the behavioral and neural level – as compared to cue-based expectations.
Enhanced memory for reward-predicting cues as compared to cues followed by rewards in unpredictable blocks may be explained by the fact that they activated the ventral striatum (Fig. 3A), which was previously found to facilitate memory formation [12] and was accompanied by medial temporal activation for subsequently remembered reward-predicting cues (Fig. 3B).
For cues, there was a significant difference with respect to memory performance between reward-predicting cues in predictable A-type blocks as compared to cues from rewarded trials in unpredictable B-type blocks (F1,14 = 5.772; p = 0.031), while memory for the non-rewarding cues in the two conditions was not different (F1,14 = 0.780; p = 0.392).
Our results are consistent with the latter findings, because we found increased bilateral ventral striatum activation not only for cues that predicted a reward (as compared to cues predicting no rewards; Fig. 3A), but also for predicted rewarding outcomes as compared to predicted non-rewarding outcomes (Fig. 5C).
Furthermore, spatially trained animals show long-term memory on retention testing, as compared to cue-trained and naïve animals.
On average, participants scored significantly higher on cognitive craving compared to cue-induced craving at all time points.
P1 amplitudes were greater in valid and neutral cue trials compared to invalid cue trials and acute nicotine administration (vs. placebo) was found to increase P1 amplitudes in the right hemisphere, particularly in valid cue trials.
We also found that when compared head-to-head, visual cues are much stronger spatial cues compared to olfactory cues.
The effect was more pronounced for saccades that were triggered by a central cue compared to peripheral cues presented at the saccade target location, and these data were particularly diagnostic in the identification of the underlying mechanism.
