Publications

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Tag: fmri3

Abstract (Expand)

Negative emotional stimuli are particularly salient events that receive privileged access to neurocognitive resources. At the neural level, the processing of negative stimuli relies on a set of sensory, limbic, and prefrontal areas. However, controversies exist on how demographic and task-related characteristics modulate this brain pattern. Here, we used activation likelihood estimation (ALE) meta-analysis and replicator dynamics to investigate the processing of negative visual stimuli in healthy adults. Our findings endorse the central role of the amygdala. This result might reflect how this structure modulates perceptual and attentional mechanisms in response to emotional stimuli. Additionally, we characterize how the neural processing of negative visual stimuli is influenced by the demographic factors of age and sex as well as by task-related characteristics like stimulus type, emotion category, and task instruction, with the amygdala showing comparable engagement across different sexes, stimulus types, and task instructions. Our findings practically inform experimentation in the affective neurosciences but also suggest brain circuits for neurobiological investigations of affective symptomatology.

Authors: I. Garcia-Garcia, J. Kube, M. Gaebler, A. Horstmann, A. Villringer, J. Neumann

Date Published: 12th May 2016

Publication Type: Not specified

Abstract (Expand)

Neural correlates of consciousness (NCC) have been a topic of study for nearly two decades. In functional imaging studies, several regions have been proposed to constitute possible candidates for NCC, but as of yet, no quantitative summary of the literature on NCC has been done. The question whether single (striate or extrastriate) regions or a network consisting of extrastriate areas that project directly to fronto-parietal regions are necessary and sufficient neural correlates for visual consciousness is still highly debated [e.g., Rees et al., 2002, Nat Rev. Neurosci 3, 261-270; Tong, 2003, Nat Rev. Neurosci 4, 219-229]. The aim of this work was to elucidate this issue and give a synopsis of the present state of the art by conducting systematic and quantitative meta-analyses across functional magnetic resonance imaging (fMRI) studies using several standard paradigms for conscious visual perception. In these paradigms, consciousness is operationalized via perceptual changes, while the visual stimulus remains invariant. An activation likelihood estimation (ALE) meta-analysis was performed, representing the best approach for voxel-wise meta-analyses to date. In addition to computing a meta-analysis across all paradigms, separate meta-analyses on bistable perception and masking paradigms were conducted to assess whether these paradigms show common or different NCC. For the overall meta-analysis, we found significant clusters of activation in inferior and middle occipital gyrus; fusiform gyrus; inferior temporal gyrus; caudate nucleus; insula; inferior, middle, and superior frontal gyri; precuneus; as well as in inferior and superior parietal lobules. These results suggest a subcortical-extrastriate-fronto-parietal network rather than a single region that constitutes the necessary NCC. The results of our exploratory paradigm-specific meta-analyses suggest that this subcortical-extrastriate-fronto-parietal network might be differentially activated as a function of the paradigms used to probe for NCC.

Authors: S. Bisenius, S. Trapp, J. Neumann, M. L. Schroeter

Date Published: 15th Nov 2015

Publication Type: Not specified

Abstract (Expand)

The current study investigated neuropsychological and underlying structural and functional brain alterations in long-term adequately treated patients with Hashimoto's thyroiditis in order to examine much discussed residual complaints in patients in relation to possible long-term neural alterations with a specific interest in the underlying autoimmune process. Eighteen patients with treated hypothyroidism due to Hashimoto's thyroiditis (mean age 32, range 18-54 years; two males; mean treatment duration 4.4 years) and 18 healthy matched control subjects underwent 3-Tesla magnetic resonance imaging (MRI). Voxel-based morphometry was used to investigate grey matter density, resting-state functional MRI to analyse the brain connectivity of areas known to be altered in hypothyroidism and event-related functional MRI to examine brain activity during associative memory encoding. Neuropsychological assessment included memory, working memory, psychomotor speed and attention. We previously reported subclinically reduced mood in this study population and investigated its neural correlates here. Thyroid stimulating hormone, free triiodthyronine, free thyroxine and thyroid peroxidase antibodies were measured in serum. We did not find cognitive deficits or alterations in grey matter density, functional connectivity or associative memory-related brain activity in comparison to the control group and cognition was unrelated to thyroid serum measures in the patient group. Thyroid peroxidase antibodies in the patient group correlated with increased grey matter density in right amygdala and enhanced connectivity between subcallosal and parahippocampal areas. Treatment duration was associated with brain structure in frontal and occipital cortex and connectivity between left amygdala and frontal cortex. Mood correlated with brain areas associated with distinct functional networks, but not with those most prominently affected in depression. In conclusion, no cognitive or neural alterations were detected in this young and otherwise healthy cohort of patients in comparison to a healthy control group and current mood status could not be related to depression-related networks. However, autoimmune activity and treatment duration showed a relationship with depression and hypothyroidism-related brain structure and function. They are thus promising factors to further investigate residual complaints despite biochemically adequate treatment in patients with Hashimoto's thyroiditis. Given the small sample size, all findings require replication.

Authors: E. M. Quinque, S. Karger, K. Arelin, M. L. Schroeter, J. Kratzsch, A. Villringer

Date Published: 19th Mar 2014

Publication Type: Not specified

Human Diseases: autoimmune thyroiditis, hypothyroidism

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