[Show abstract][Hide abstract] ABSTRACT: Fixed stimulus presentation times pose several methodological problems for developmental functional magnetic resonance imaging (fMRI) studies that can be avoided by self-paced study designs. Yet, methodological issues of self-paced stimulus presentation for fMRI studies are largely understudied. Therefore, we compared sensitivity, reproducibility, and reliability of neural activation of a fixed and a self-paced design for an exact, non-symbolic addition paradigm in a sample of children aged 6-12 years. Both design types were comparable in sensitivity, and the self-paced design was superior in reproducibility and reliability. Therefore, self-paced study designs seem to be a valid option for developmental fMRI studies on higher cognition.
[Show abstract][Hide abstract] ABSTRACT: The purpose of the present study was to establish a short paradigm for the examination of classical aversive conditioning processes for application in patients with anxiety disorders. We measured behavioral, autonomic and neural correlates of the paradigm in healthy subjects, applying functional magnetic resonance imaging (fMRI) and measurement of skin conductance. Therefore, neutral visual stimuli were paired with an unpleasant white noise as unconditioned stimulus. Twenty healthy subjects performed three experimental phases of learning: familiarization, acquisition and extinction. Subjective ratings of valence and arousal after each phase of conditioning as well as skin conductance measurement indicated successful conditioning. During acquisition, fMRI results showed increased activation for the conditioned stimulus (CS+(unpaired)) when compared with the non-conditioned stimulus (CS-) in the right amygdala, the insulae, the anterior cingulate cortex and the parahippocampal gyrus, all regions known to be involved in emotional processing. In addition, a linearly decreasing activation in the right amygdala/hippocampus for the CS- across the acquisition phase was found. There were no significant differences between CS+ and CS- during extinction. In conclusion, the applicability of this paradigm for the evaluation of neural correlates in conditioning and extinction processes has been proven. Thus, we present a promising paradigm for the examination of the fear-circuit in patients with anxiety disorders and additionally effects of cognitive-behavioral interventions.
European Archives of Psychiatry and Clinical Neuroscience 02/2010; 260(6):443-53. · 2.75 Impact Factor