Pavlovian biconditional discrimination learning in the C57BL/6J Mouse

Abstract

Four experiments using mice examined acquisition of Pavlovian biconditional discriminations in which two stimulus compounds were paired with food (AX+ and BY+) and two were not (AY− and BX−). Temporally asynchronous compounds were generated by using contextual stimuli (Experiment 1) and 15-sec discrete visual cues (Experiments 2A, 2B and 3) to disambiguate when embedded noise or tone stimuli would be paired with food. When food pellets followed both reinforced compounds, successful acquisition was obtained in Experiment 1 but not in Experiments 2A and 2B even though the order of trials was modeled after that used in Experiment 1. However, when differential outcomes followed the reinforced compounds in Experiment 3, acquisition was obtained with discrete cue stimulus compounds. The implications of these results for modulatory models of conditional discrimination learning in animals are discussed.

Pavlovian contextual and instrumental biconditional discrimination learning in mice

“…First, in our demonstration of successful acquisition of a Pavlovian contextual BCD, we used simple contexts that were constructed by adding or removing a floor cover in the same box located in the same physical space. Other BCD studies have used more complex multidimensional contexts comprised from one or more sensory modalities and located in different rooms or areas of a room [11, 26-30]. An important advantage of simplifying the differences between contextual biconditional cues is that any variations in contextual BCD performance between control and genetically-modified mice cannot be attributed to their use of different features of a multimodal context or to differences in their ability to integrate those features into an internal representation of that context.…”

“…This type of concern has been addressed in other studies by examining BCD performance in extinction [26, 33] or on the first trial of the day [28]. An alternative approach used in our study was to see if mice could in fact learn to use such a rule to support differential responding during training when no other solution was available.…”

“…However, the present data do not distinguish among the various associative structures that might have been used to solve the BCDs. Elsewhere, we have discussed how different permutations of binary or hierarchical associations might subserve Pavlovian contextual BCD performance [26]. We have also provided a comprehensive analysis of instrumental BCD performance in rats when the same outcome is used to reinforce correct responses in each cue [8].…”

“…Previous studies of contextual BCD learning have consistently used contexts that differed not only in appearance but in their physical location [11, 26-30]. We eliminated differences in physical location by using the same box in the same location with the grid floor exposed (Context A) or covered with a plastic insert (Context B) to create the two distinctive contextual cues.…”

“…For example, if contextual cues differing in physical location or in features such as odor or substrate are used to disambiguate when a target is reinforced and when it is not, target training with each contextual cue has to be conducted in separate sessions. Consequently, during training, target outcomes at the start of a session could guide responding for the remainder of that session [26]. Similarly, in an instrumental BCD, a win-stay, lose-shift strategy could generate reliable and appropriate differential responding during training.…”