The session started with the lever associated with the two pellet reward being presented.
We previously showed that rats would preferentially press a lever associated with a 2-pellet reward than one associated with a single pellet reward, even when they had to perform 13 times as many presses for the bigger reward (the maximum ratio tested) [40].
This difference shows that animals have effectively learned that each lever is associated with a different outcome.
Thus, the CS+ sucrose cue selectively triggered increased pressing only on the lever previously associated with obtaining sucrose.
The light stayed lit for as long as the lever was associated with reinforcement, but was turned off during reinforcer presentation.
However, during the initial training in this task, presses on the left lever were associated with a small reinforcement whereas presses on the right one resulted in a large reinforcement with no delay.
A magnified peak of pressing on the lever previously associated with sucrose reward was triggered anew by each presentation of the CS+ sucrose cue after CRF (500) or amphetamine microinjections, maximally elevating during its 30-sec period (Two-way ANOVA (cue presence × cue presentation order), F1,79 = 16.11, p < 0.001; main effect of cue presence).
For example, when rats are trained on a tri-peak procedure in which three levers are individually associated with different durations initiated by the onset of a single signal, the responses on the three levers demonstrate a high degree of independence, suggesting the use of independent clocks rather than a single stopwatch [11], [12].
Long levers were also associated with the trunk and lower limb angles.
PTX3 levers were positively associated with the severity of coronary artery lesions.
