Brief learning induces a memory bias for arousing-negative words: an fMRI study in high and low trait anxious persons.
Persons suffering from anxiety disorders display facilitated processing of arousing and negative stimuli, such as negative words. This memory bias is reflected in better recall and increased amygdala activity in response to such stimuli. However, individual learning histories were not considered in most studies, a concern that we meet here. Thirty-four female persons (half with high-, half with low trait anxiety) participated in a criterion-based associative word-learning paradigm, in which neutral pseudowords were paired with aversive or neutral pictures, which should lead to a valence change for the negatively paired pseudowords. After learning, pseudowords were tested with fMRI to investigate differential brain activation of the amygdala evoked by the newly acquired valence. Explicit and implicit memory was assessed directly after training and in three follow-ups at 4-day intervals. The behavioral results demonstrate that associative word-learning leads to an explicit (but no implicit) memory bias for negatively linked pseudowords, relative to neutral ones, which confirms earlier studies. Bilateral amygdala activation underlines the behavioral effect: Higher trait anxiety is correlated with stronger amygdala activation for negatively linked pseudowords than for neutrally linked ones. Most interestingly, this effect is also present for negatively paired pseudowords that participants could not remember well. Moreover, neutrally paired pseudowords evoked higher amygdala reactivity than completely novel ones in highly anxious persons, which can be taken as evidence for generalization. These findings demonstrate that few word-learning trials generate a memory bias for emotional stimuli, indexed both behaviorally and neurophysiologically. Importantly, the typical memory bias for emotional stimuli and the generalization to neutral ones is larger in high anxious persons.
Institute of Biomagnetism and Biosignalanalysis, University Hospital of Münster Münster, Germany ; Institute of Psychology, University of Münster Münster, Germany.
Annuschka S
AS
Eden
Institute of Biomagnetism and Biosignalanalysis, University Hospital of Münster Münster, Germany ; Institute of Psychology, University of Münster Münster, Germany.
Vera
V
Dehmelt
Institute of Sport and Exercise Sciences, University of Münster Münster, Germany.
Matthias
M
Bischoff
Department of Psycholinguistics and Cognitive Neurosciences, Institute of Psychology, University of Münster Münster, Germany.
Pienie
P
Zwitserlood
Department of Clinical Radiology, University of Münster Münster, Germany.
Harald
H
Kugel
University of Hong Kong Hong Kong, Hong Kong.
Kati
K
Keuper
kbo-Inn-Salzach Clinic, Academic Hospital of Psychiatry, Psychotheray and Neurology Wasserburg am Inn, Germany.
Peter
P
Zwanzger
Institute of Biomagnetism and Biosignalanalysis, University Hospital of Münster Münster, Germany ; Department of Psychology, University of Bielefeld Bielefeld, Germany ; Department of Otolaryngology, Jena University Hospital Jena, Germany.
Christian
C
Dobel
amygdala; consolidation; emotions; fMRI; memory bias; statistical word-learning; trait anxiety