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.

No abstract

No abstract

This study demonstrates the link between cerebral correlates of cognitive (IFG) and emotional ("fear network") processing during symptom improvement across time in PD/A. Further research along this line has promising potential to support the development and further optimization of targeted treatments.

Our results suggest that structural changes in the pain system are associated with fibromyalgia. As disease factors do not correlate with reduced gray matter volume in areas of the cingulo-frontal cortex and the amygdala in patients, one possible interpretation is that volume reductions might be a precondition for central sensitization in fibromyalgia.

Our results indicate that major depressive disorder is accompanied by state-dependent metabolic alterations, especially in glutamate/glutamine metabolism, which can be reversed by successful ECT.

Negatively balanced neurotrophic factors may be important in precipitating clinical depression. Recently, it has been reported that antidepressant therapy may exert positive neurotrophic effects. The aim of this study was to detect probable neurotrophic changes during electroconvulsive therapy (ECT). For this purpose, N-acetylaspartate (NAA), an amino acid exclusively located in neurons, and other brain metabolites such as glutamine/glutamate (Glx), choline (Cho), and creatine (Cr) were measured in patients by localized proton magnetic resonance spectroscopy. A total of 28 severely depressed patients (DSM-IV) were enrolled, and the left amygdalar region was investigated by proton STEAM spectroscopy before and after unilateral ECT. The results were compared with 28 age-and gender-matched controls using nonparametric paired and unpaired tests. A significant increase in NAA was observed only in ECT responders (n ¼ 14; p ¼ 0.019). Five out of 14 nonresponders to ECT monotherapy were remeasured following a clinical improvement after continued ECT combined with antidepressants and were then found also to present a significant increase in NAA. In all successfully treated patients, parallel observations, that is, increased levels, were made for Glx, whereas Cho and Cr were unchanged. In conclusion, our preliminary finding of increased NAA concentrations after successful ECT may indicate a probable neurotrophic effect of ECT. Neuropsychopharmacology (2003) 28, 720-725.

There are gender-specific differences not only in the quality, localization and triggering of CP but also in the underlying disease and scratching behaviour. These facts must be taken into account in the medical care of patients with CP and when conducting any kind of clinical research on itch. Further research is needed to achieve a gender-specific and gender-adapted diagnostics and treatment of CP.