Expecting unpleasant stimuli--an fMRI study.
ABSTRACT Expecting forthcoming events and preparing adequate responses are important cognitive functions that help the individual to deal with the environment. The emotional valence of an event is decisive for the resulting action. Revealing the underlying mechanisms may help to understand the dysfunctional information processing in depression and anxiety that are associated with negative expectation of the future. We were interested in selective brain activity during the expectation of unpleasant visual stimuli. Twelve healthy female subjects were biased to expect and then perceive emotionally unpleasant, pleasant or neutral stimuli during functional magnetic resonance imaging. Expecting unpleasant stimuli relative to expecting pleasant and neutral stimuli resulted in activation of mainly cingulate cortex, insula, prefrontal areas, thalamus, hypothalamus and striatum. While certain areas were also active during subsequent presentation of the emotional stimuli, distinct regions of the anterior cingulate gyrus and the thalamus were solely active during expectation of the unpleasant stimuli. The identified areas may reflect a network for internal adaptation and preparation processes in order to react adequately to expected unpleasant events. They are known as well to be altered in depression. Disorders of this network may be relevant for psychiatric disorders such as depression.
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ABSTRACT: Idiopathic environmental intolerance (IEI) to smells is a prevalent medically unexplained illness. Sufferers attribute severe symptoms to low doses of non-toxic chemicals. Despite the label, IEI is not characterized by acute chemical senses. Theoretical models suggest that sensitized responses in the limbic system of the brain constitute an important mechanism behind the symptoms. The aim was to investigate whether and how brain reactions to low-levels of olfactory and trigeminal stimuli differ in individuals with and without IEI.Journal of Psychosomatic Research 10/2014; 77(5). DOI:10.1016/j.jpsychores.2014.09.014 · 2.84 Impact Factor
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ABSTRACT: Learning to predict rewarding and aversive outcomes is based on the comparison between predicted and actual outcomes (prediction error: PE). Recent electrophysiological studies reported that during a Pavlovian procedure some dopamine neurons code a classical PE signal while a larger population of dopaminergic neurons reflect a "salient" prediction error (SPE) signal, being excited both by unpredictable aversive events and by rewards. Yet, it is still unclear whether specific human brain structures receiving afferents from dopaminergic neurons code a SPE and whether this signal depends upon reinforcer type. Here, we used a model-based functional magnetic resonance imaging approach implementing a reinforcement learning model to compute the PE while subjects underwent a Pavlovian conditioning procedure with 2 types of rewards (pleasant juice and monetary gain) and 2 types of punishments (aversive juice and aversive picture). The results revealed that activity of a brain network composed of the striatum, anterior insula, and anterior cingulate cortex covaried with a SPE for appetitive and aversive juice. Moreover, amygdala activity correlated with a SPE for these 2 reinforcers and for aversive pictures. These results provide insights into the neurobiological mechanisms underlying the ability to learn stimuli-rewards and stimuli-punishments contingencies, by demonstrating that the network reflecting the SPE depends upon reinforcement's type.Cerebral Cortex 02/2012; DOI:10.1093/cercor/bhs037 · 8.31 Impact Factor
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ABSTRACT: Women and men differ in the way they experience emotional events. Previous work has indicated that the impact of an emotional event depends on how it is anticipated. Separately, it has been shown that anticipation affects memory formation. Here, we assessed whether anticipatory brain activity influences the encoding of emotional events into long-term memory and, in addition, how biological sex affects the use of such activity. Electrical brain activity was recorded from the scalps of healthy men and women while they performed an incidental encoding task (indoor/outdoor judgments) on pleasant, unpleasant, and neutral pictures. Pictures were preceded by a cue that indicated the valence of the upcoming item. Memory was tested after a 20 min delay with a recognition task incorporating the remember/know procedure. Brain activity before picture onset predicted later memory of an event. Crucially, the role of anticipatory activity depended entirely on the valence of a picture and the sex of an individual. Right-lateralized anticipatory activity selectively influenced the encoding of unpleasant pictures in women, but not in men. These findings indicate that anticipatory processes influence the way in which women encode negative events into memory. The selective use of such activity may indicate that anticipatory activity is one mechanism by which individuals regulate their emotions.The Journal of Neuroscience : The Official Journal of the Society for Neuroscience 08/2011; 31(34):12364-70. DOI:10.1523/JNEUROSCI.1619-11.2011 · 6.75 Impact Factor