Journal Article

Human Fear Conditioning and Extinction in Neuroimaging: A Systematic Review

Konrad, Carsten, Sehlmeyer, Christina, Pfleiderer, Bettina, Kircher, Tilo, Zwitserlood, Pienie, Schöning, Sonja, Arolt, Volker

2009

Overview

Fear conditioning and extinction are basic forms of associative learning that have gained considerable clinical relevance in enhancing our understanding of anxiety disorders and facilitating their treatment. Modern neuroimaging techniques have significantly aided the identification of anatomical structures and networks involved in fear conditioning. On closer inspection, there is considerable variation in methodology and results between studies. This systematic review provides an overview of the current neuroimaging literature on fear conditioning and extinction on healthy subjects, taking into account methodological issues such as the conditioning paradigm. A Pubmed search, as of December 2008, was performed and supplemented by manual searches of bibliographies of key articles. Two independent reviewers made the final study selection and data extraction. A total of 46 studies on cued fear conditioning and/or extinction on healthy volunteers using positron emission tomography or functional magnetic resonance imaging were reviewed. The influence of specific experimental factors, such as contingency and timing parameters, assessment of conditioned responses, and characteristics of conditioned and unconditioned stimuli, on cerebral activation patterns was examined. Results were summarized descriptively. A network consisting of fear-related brain areas, such as amygdala, insula, and anterior cingulate cortex, is activated independently of design parameters. However, some neuroimaging studies do not report these findings in the presence of methodological heterogeneities. Furthermore, other brain areas are differentially activated, depending on specific design parameters. These include stronger hippocampal activation in trace conditioning and tactile stimulation. Furthermore, tactile unconditioned stimuli enhance activation of pain related, motor, and somatosensory areas. Differences concerning experimental factors may partly explain the variance between neuroimaging investigations on human fear conditioning and extinction and should, therefore, be taken into serious consideration in the planning and the interpretation of research projects.

• Publisher: Public Library of Science,Public Library of Science (PLoS)
• Subject: Activation / Adult / Amygdala / Amygdala - metabolism / Animal cognition / Anxiety / Associative learning / Avoidance Learning - physiology / Brain / Brain - anatomy & histology / Brain - pathology / Brain - physiology / Brain mapping / Brain Mapping - methods / Cerebrum / Conditioning / Conditioning (learning) / Conditioning, Psychological - physiology / Contingency / Cortex (cingulate) / Cortex (somatosensory) / Design parameters / Diagnostic imaging / Electrophysiology - methods / Emotions / Extinction / Extinction behavior / Extinction, Psychological - physiology / Fear / Fear & phobias / Fear - physiology / Fear conditioning / Female / Functional magnetic resonance imaging / Hippocampus / Hippocampus - physiology / Humans / Influence / Inspection / Interdisciplinary aspects / Magnetic resonance / Magnetic resonance imaging / Magnetic Resonance Imaging - methods / Male / Medical imaging / Memory / Mental Health/Mood Disorders / Mental Health/Psychology / Middle Aged / Neuroimaging / Neurology / Neuroscience / Neuroscience/Psychology / Pain / Personality / Personality traits / Positron emission / Positron emission tomography / Psychiatry / Psychotherapy / Radiology and Medical Imaging/Magnetic Resonance Imaging / Research projects / Reviews / Somatosensory cortex / Stimuli / Studies / Tactile / Tactile stimuli / Trace conditioning