Occasion setting

Abstract

Occasion setting refers to the ability of 1 stimulus, an occasion setter, to modulate the efficacy of the association between another, conditioned stimulus (CS) and an unconditioned stimulus (US) or reinforcer. Occasion setters and simple CSs are readily distinguished. For example, occasion setters are relatively immune to extinction and counterconditioning, and their combination and transfer functions differ substantially from those of simple CSs. Similarly, the acquisition of occasion setting is favored when stimuli are separated by longer intervals, by empty trace intervals, and are of different modalities, whereas the opposite conditions typically favor the acquisition of simple associations. Furthermore, the simple conditioning and occasion setting properties of a single stimulus can be independent, for example, that stimulus may simultaneously predict the occurrence of a reinforcer and indicate that another stimulus will not be reinforced. Many behavioral phenomena that are intractable to simple associative analysis are better understood within an occasion setting framework. Besides capturing the distinction between direct and modulatory control common to many arenas in neuroscience, occasion setting provides a model for the hierarchical organization of memory for events and event relations, and for contextual control more broadly. Although early lesion studies further differentiated between occasion setting and simple conditioning functions, little is known about the neurobiology of occasion setting. Modern techniques for precise manipulation and monitoring of neuronal activity in multiple brain regions are ideally suited for disentangling contributions of simple conditioning and occasion setting in associative learning. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

Figure 1.. Schematic of associative structures of serial or simultaneous feature training.

Associative structures established in simultaneous (panels A and C) and serial (panels B and D) feature positive (panels A and B) and feature negative (panels C and D) discriminations. F and T refer to representations of feature and target stimuli, respectively, US refers to a representation of the unconditioned stimulus, and X refers to a representation of a transfer test stimulus paired with the US outside of the discrimination task (see sections on transfer effects in “Assays of occasion setting” and “Contents of Occasion setting”). Arrows indicate excitatory associations and bars indicate inhibitory associations. Filled circles indicate positive modulatory (occasion setting) links and open circles indicate negative modulatory links. The dotted arrows refer to excitatory associations established after counterconditioning of the feature (see sections on counterconditioning in “Assays of occasion setting” and “Contents of Occasion setting”).

Figure 2.. Alternative associative structures established in serial feature negative discriminations.

Panel A shows a structure in which a representation of the feature (F) suppresses processing of a representation of the target (T), and Panel B shows a structure in which a representation of F suppresses processing or raises the activation threshold of a representation of the unconditioned stimulus (US). X refers to a representation of a transfer test stimulus paired with the US outside of the discrimination task (see sections on transfer effects in “Assays of occasion setting” and “Contents of Occasion setting”). Arrows indicate simple excitatory associations and open circles indicate negative modulatory (occasion setting) links. The dotted arrows refer to excitatory associations established after counterconditioning (see sections on counterconditioning in “Assays of occasion setting” and “Contents of Occasion setting”).

Figure 3.. Associative structure in multiple feature training.

Representation of associative structure after multiple feature positive (FP) or feature negative (FN) discriminations (after Estes, 1969). US1/US2 refer to two different unconditioned stimuli, and X and Y refer to stimuli separately paired with US1 or US2, respectively. F1/F2 and T1/T2 refer to the features and targets (respectively) used in two separate FP or FN discriminations. The circles labeled CE refer to control elements established as a result of this training, which modulate the associations between T1 and US1 and between T2 and US1 or US2 (dotted lines). See the section “Loci of action of occasion setters and simple CSs” for more explanation.

Figure 4.. Neurobiological substrates of occasion setting.

Sagittal section of a rat brain illustrating regions implicated in occasion setting and their relevant circuitry is indicated by the directional arrows. Green shading indicates regions for which evidence implicates activity within this region as being critical for the acquisition or expression of occasion setting. Other regions shaded in blue are implicated in simple Pavlovian conditioning but a role for these regions in occasion setting remains to be demonstrated. Evidence for the involvement of the dHIPP, shaded in red, in occasion setting is mixed and requires further study. BLA basolateral amygdala, dHIPP dorsal hippocampus, mPFC medial prefrontal cortex, NAc nucleus accumbens, OFC orbitofrontal cortex, PVT paraventricular nucleus of the thalamus, vHIPP ventral hippocampus, VTA ventral tegmental area.