Expecting unpleasant stimuli - An fMRI study
Psychiatric University Hospital, Zürich, Switzerland. Psychiatry Research
(Impact Factor: 2.47).
02/2007; 154(1):1-12. DOI: 10.1016/j.pscychresns.2006.02.007
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.
Available from: Berndt Stenberg
- "This argument is also in line with previous studies suggesting increased salience of, and attention bias to chemical exposure in CI  and IEI . It is also possible that the lower prefrontal BOLD signal found in the IEI group reflects higher baseline than that of controls, possibly due to expectancy of exposure  . With the exception of the precuneus, the current results do not overlap those reported by Hillert and colleagues  who studied MCS using positron emission tomography. "
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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.
Brain responses to intranasally delivered isoamyl acetate and carbon dioxide were assessed in 25 women with IEI and 26 non-ill controls using functional magnetic resonance imaging.
The IEI group had higher blood-oxygenated-level-dependent (BOLD) signal than controls in the thalamus and a number of, mainly, parietal areas, and lower BOLD signal in the superior frontal gyrus. The IEI group did not rate the exposures as more intense than the control group did, and there were no BOLD signal differences between groups in the piriform cortex or olfactory regions of the orbitofrontal cortex.
The IEI reactions were not characterized by hyper-responsiveness in sensory areas. The results can be interpreted as a limbic hyperreactivity and speculatively as an inability to inhibit salient external stimuli.
Journal of Psychosomatic Research 10/2014; 77(5). DOI:10.1016/j.jpsychores.2014.09.014 · 2.74 Impact Factor
Available from: PubMed Central
- "This includes changes in subjective experiences, autonomic reactions and neural responses (Drabant et al., 2011). Neuroimaging studies have shown that activity in brain regions such as the amygdala, prefrontal cortex, insula and anterior cingulate cortex increases during the anticipation of negative events (Nitschke et al., 2006; Paulus and Stein, 2006; Herwig et al., 2007). While emotional reactivity can be adaptive to some extent, excessive negative anticipation may affect the development and maintenance of psychiatric symptoms (Beck, 1967; Eysenck, 1992). "
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ABSTRACT: It has been shown that the effectiveness with which unpleasant events are encoded into memory is related to brain activity set in train before the events. Here, we assessed whether encoding-related activity before an aversive event can be modulated by emotion regulation. Electrical brain activity was recorded from the scalps of healthy women while they performed an incidental encoding task on randomly intermixed unpleasant and neutral visual scenes. A cue presented 1.5 s before each picture indicated the upcoming valence. In half of the blocks of trials, the instructions emphasized to let emotions arise in a natural way. In the other half, participants were asked to decrease their emotional response by adopting the perspective of a detached observer. Memory for the scenes was probed one day later with a recognition memory test. Brain activity before unpleasant scenes predicted later memory of the scenes, but only when participants felt their emotions and did not detach from them. The findings indicate that emotion regulation can eliminate the influence of anticipatory brain activity on memory encoding. This may be relevant for the understanding and treatment of psychiatric diseases with a memory component.
Social Cognitive and Affective Neuroscience 11/2012; 9(3). DOI:10.1093/scan/nss145 · 7.37 Impact Factor
Available from: Jean-Claude Dreher
- "The ROIs were created in 3 stages. First, we identified several brain regions that have established roles during aversive and appetitive conditioning: the striatum, the insula, the anterior cingulate cortex (ACC) and the amygdala (Jensen et al. 2003; Seymour et al. 2004; Bray and O'Doherty 2007; Herwig et al. 2007; Sescousse et al. 2010). Second, we built 7 anatomical ROIs defined with the probabilistic atlas of Hammers et al. (2003): the ACC ROI resulted from the union of left and right ACC cortex and the other anatomical ROIs were left/right insula, left/right amygdala, and left/right striatum. "
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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; 23(2). DOI:10.1093/cercor/bhs037 · 8.67 Impact Factor
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