Beyond the classic extinction network: a wider, comparative view

Onur Güntürkün,Sarah Starosta,Dagmar Timmann,Meng Gao,Mark E Ladd,Harald H Quick,Maik C Stüttgen,Michael Nitsche,Roland Pusch,Thomas M Ernst

doi:10.1515/nf-2020-0015

Abstract

Abstract Extinction learning modifies the dynamics of brain circuits such that a previously learned conditioned response is no longer generated. The majority of extinction studies use fear conditioning in rodents and identified the prefrontal cortex, the hippocampus, and the amygdala as core regions of the extinction circuit. We sought to find answers to two questions: First, do we find a similar functional brain circuit in birds, which underwent a 300-million-year separate evolution from mammals? Second, do we have to incorporate the cerebellum as a key component of the central extinction circuit? We indeed show that the avian extinction pathways are not identical but highly similar to those of mammals. In addition, we reveal that the human cerebellum processes prediction errors, a key element driving extinction of learned fear responses, and contributes to context-related effects of extinction.

Highlights

Animals rapidly learn to predict which stimuli are followed by reward or punishment, or, in more general terms, by an expected unconditioned stimulus (US)
The principles of extinction learning were demonstrated to be largely similar in animals that reach from humans (Icenhour et al, 2015) to insects (Felsenberg et al, 2018)
Is this the case? This question is at the core of the first part of this article in which we study extinction circuits in pigeons

Summary

Introduction

Animals rapidly learn to predict which stimuli are followed by reward or punishment, or, in more general terms, by an expected unconditioned stimulus (US). Hahn Institute for Magnetic Resonance Imaging, University of Duisburg-Essen, 45141 Essen, Germany; HighField and Hybrid MR Imaging, Essen University Hospital, 45147 Essen, Germany, E-mail: harald.quick@uni-due.de cerebellum processes prediction errors, a key element driving extinction of learned fear responses, and contributes to context-related effects of extinction. The cerebellum plays an important role in the processing of prediction errors in sensory and reward-related domains and controls core elements of associative learning.

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