Elsevier

Biological Psychology

Volume 100, July 2014, Pages 1-12
Biological Psychology

Review article
Fear conditioning and extinction across development: Evidence from human studies and animal models

https://doi.org/10.1016/j.biopsycho.2014.04.001Get rights and content

Highlights

  • Successful fear conditioning and fear extinction in humans and rodents is highly dependent on the selection of a strong, potent, and evolutionarily relevant UCS.

  • Fear acquisition is present in children as early as 3 months of age with older children showing increased CR compared to younger children.

  • The available developmental data from research in animal models may suggest an essential difference in the neural architecture underlying fear extinction across development.

  • Amygdala, insula and anterior cingulate (ACC) are implicated in human fear conditioning independent of the specific fear conditioning paradigm used.

  • Similar to findings in animal models, neuroimaging studies in humans implicate the pivotal role of amygdala, PFC and hippocampus in extinction learning.

Abstract

The ability to differentiate danger and safety through associative processes emerges early in life. Understanding the mechanisms underlying associative learning of threat and safety can clarify the processes that shape development of normative fears and pathological anxiety. Considerable research has used fear conditioning and extinction paradigms to delineate underlying mechanisms in animals and human adults; however, little is known about these mechanisms in children and adolescents. The current paper summarizes the empirical data on the development of fear conditioning and extinction. It reviews methodological considerations and future directions for research on fear conditioning and extinction in pediatric populations.

Introduction

The ability to identify danger emerges early in life and develops in a similar way across cultures. Young children tend to fear strangers or separation. When these fears diminish during school-age, they typically are replaced by fears of animals or other natural dangers. In adolescence, fears arise of social circumstances and abstract dangers, such as the fear of humiliation. While extensive research charts developmental patterns of human fear in response to such intrinsically threatening events, far less research examines developmental aspects of learned fears. Because considerable basic research examines fear conditioning and extinction, particular interest has arisen in the development of these forms of learning.

This paper summarizes findings from developmental research on fear conditioning and extinction. It unfolds in four stages. Section 2 defines major concepts relevant to fear conditioning and extinction. Because few studies examine fear conditioning and extinction in children, Section 3 attempts to extrapolate to children and adolescents from data in animals and human adults. Section 4 details findings from the few available conditioning and extinction studies in children and adolescents, emphasizing the unique ethical and methodological considerations that complicate such work. The paper concludes by summarizing directions for future studies.

Section snippets

Studying fear conditioning and extinction developmentally

Fear conditioning, a form of associative learning, is a widely used experimental paradigm for investigating the psychophysiological processes and neural mechanisms sub-serving learning about danger cues in a range of mammalian species. In classical fear conditioning, a neutral conditioned stimulus (CS, e.g., tone) is repeatedly paired with an aversive stimulus (UCS, e.g., shock), yielding a CS-UCS association. Discrimination conditioning uses two CSs, one that is paired with the UCS (CS+) and

The neural circuitry underpinning fear conditioning and extinction

Most neuroscience research on fear conditioning uses animal models. Nonetheless, translating these findings to human studies is feasible due to the strong cross-species similarities in the physiology of fear (LeDoux, 2000). Animal models are particularly important for studying the emergence of fear conditioning across development as some of the procedures are less feasible in humans and particularly in children and adolescents. Therefore, findings from animal models can be translated to

Fear conditioning and extinction studies in children and adolescents

One of the first documented classical conditioning studies in infants was conducted by Watson and Rayner (1920). In their early studies, they demonstrated that fear can be learned through conditioning presented through repeated pairings of a neutral stimulus (e.g., white rat) with a loud noise (Watson & Rayner, 1920). In another study, 12 full-term infants as young as 3 months of age showed greater response magnitude to the CS+ compared to the CS− as indexed by skin conductance response (SCR) (

Insights for future developmental research on fear conditioning

There is a need for research on fear conditioning and extinction processes in children to gain additional understanding of the underlying behavioral, physiological, and neural mechanisms associated with normative and pathological fear learning across development. The majority of studies conducted on this topic have primarily focused on fear conditioning and extinction during late childhood and adolescence but rarely have they focused on infancy or early childhood. Given the developmental

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    This study was supported (partially) by the NIMH Intramural Research Program.

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