Left Inferior Frontal Gyrus Participates in Mediating the Renewal Effect Irrespective of Context Salience.

Martin Tegenthoff,Silke Lissek,Anne Klass

doi:10.3389/fnbeh.2020.00043

Abstract

The renewal effect of extinction demonstrates the context-dependency of extinction learning. It is defined as the recovery of an extinguished response occurring when the contexts of extinction and recall differ. Behavioral studies showed that modulating context relevance can strengthen context-specific responses. In our fMRI study, we investigated to what extent a modulation of context salience can alter renewal levels and provide additional information about the neural basis for renewal. In a within-subjects design, participants completed two sessions of an associative learning task in randomized order. In the salient condition (SAL), a context was presented alone at the start of each trial, before being presented together with the stimulus. The regular condition (REG) contained no context-alone phase. In about one-third of participants (SWITCH), the context salience modulation significantly increased renewal rates in the SAL compared to the REG condition. The other participants showed either renewal (REN) or no renewal (NoREN) in both conditions. The modulation did not significantly affect learning performance during the initial forming of associations or extinction learning. In the SWITCH group, activation in left opercular inferior frontal gyrus (iFG) during the recall phase was associated with a renewal effect, together with activity in the bilateral posterior hippocampus and ventromedial prefrontal cortex (vmPFC). Also during the extinction phase, left opercular iFG activation was higher in groups exhibiting renewal in recall, irrespective of the context salience modulation. Besides confirming the participation of vmPFC in extinction recall, our findings provide novel insights regarding an as yet undetected, potentially important role for renewal-supporting processes in left iFG during extinction learning and recall, which are presumably based on the region’s proposed function of evaluating competing response options under conditions of ambiguity.

Highlights

The renewal effect of extinction is defined as the reoccurrence of an extinguished response when recall is performed in a context that differs from the one present during extinction learning (Bouton and Bolles, 1979)
While most research on extinction learning and renewal has focussed on fear extinction, the renewal effect is observed in non-fear related learning, such as instrumental and appetitive extinction in animals (Bouton and Peck, 1989; Bouton and Todd, 2014)
To identify brain areas processing renewal-related information during recall and extinction learning, we focussed on activation

Summary

Introduction

The renewal effect of extinction is defined as the reoccurrence of an extinguished response when recall is performed in a context that differs from the one present during extinction learning (Bouton and Bolles, 1979). This context-dependency of renewal can pose serious problems for exposure therapies of phobias, since therapeutic success may not transfer from the therapeutic. In studies on extinction without a fear component, typically only a certain percentage (45–65%) of participants exhibit a renewal effect of extinction ( e.g., Lissek et al, 2013, 2016) This phenomenon makes non-fear related extinction tasks useful for the investigation of renewal since opposing responses to an identical input can be analyzed. Further supporting the assumption of an enduring, favored processing tendency is the finding that participants who show renewal consider the context during extinction, due to the unexpected change of contingencies that supposedly directs attention to the context (Bouton, 2004; Rosas and Callejas-Aguilera, 2006), but already during the acquisition of a context-related task, even though in this initial phase the context is not yet relevant (Lissek et al, 2016)

Methods

Discussion

Conclusion