Hans J. Mentzel

Modulation of the neural network involved in the processing of anger prosody: the role of task-relevance and social phobia

Individuals with social phobia display neural hyperactivation towards angry facial expressions. However, it is uncertain whether they also show abnormal brain responses when processing angry voices. In an event-related functional magnetic resonance imaging study, we investigated brain responses to neutral and angry voices in 12 healthy control participants and 12 individuals with social phobia when emotional prosody was either task-relevant or task-irrelevant. Regardless of task, both phobic and non-phobic participants recruited a network comprising frontotemporal regions, the amygdala, the insula, and the striatum, when listening to angry compared to neutral prosody. Across participants, increased activation in orbitofrontal cortex during task-relevant as compared to task-irrelevant emotional prosody processing was found. Compared to healthy controls, individuals with social phobia displayed significantly stronger orbitofrontal activation in response to angry versus neutral voices under both task conditions. These results suggest a disorder-associated increased involvement of the orbitofrontal cortex in response to threatening voices in social phobia.

Brain activation to phobia-related words in phobic subjects.

Behavioural studies suggest that phobic subjects are hypersensitive in the processing of phobia-related linguistic stimuli. We used functional magnetic resonance imaging (fMRI) to investigate blood oxygen level dependent (BOLD) brain activation to phobia-relevant words in spider phobic and non-phobic subjects. Phobia-related versus phobia-unrelated words elicited increased activation in prefrontal cortex, insula, and posterior cingulate cortex in spider phobics, while these effects were absent in controls. Furthermore, between-group comparisons confirmed that differential activations within these brain regions were specifically due to increased responses to phobia-related stimuli in phobics. Our results provide first insights into brain activation patterns when phobics are confronted with phobia-specific linguistic information und suggest a neural network for the processing of these threatening stimuli.

Influence of Galantamine on Vasomotor Reactivity in Alzheimer’s Disease and Vascular Dementia Due to Cerebral Microangiopathy

Background and Purpose— Recent reports suggest that vascular factors play a crucial role in the development and progression of Alzheimer’s disease. We aimed to assess vasomotor reactivity in patients with Alzheimer’s disease and vascular dementia due to microangiopathy using transcranial Doppler sonography and near-infrared spectroscopy during a CO2 exposition task. Methods— The normalized CO2 reactivity assessed at the middle cerebral artery and the oxygenated and deoxygenated hemoglobin of the frontal cortex were obtained. To investigate the impact of cholinergic deficiency known for Alzheimer’s disease on vasomotor reactivity, both groups were reinvestigated during treatment with the acetylcholine esterase inhibitor galantamine. Results— Transcranial Doppler analysis revealed significantly reduced normalized CO2 reactivity for Alzheimer’s disease and vascular dementia. Vasomotor reactivity assessed by near-infrared spectroscopy was decreased in patients with vascular dementia, but not in Alzheimer’s disease. Galantamine treatment showed a beneficial effect, normalizing these parameters close to age-matched control levels. Conclusions— Our results suggest that Alzheimer’s disease is associated with a lack of vasomotor reactivity, which might be associated with disturbed autoregulation indicating a potential risk for a decreased protection of brain tissue against blood pressure changes. Additionally, a diminished increase of cortical oxygenated hemoglobin during the CO2 test was apparent in patients with vascular dementia. Galantamine treatment influenced vascular reactivity in the CO2 test, thus providing evidence for the cholinergic deficiency, thereby adding to vascular dysregulation in Alzheimer’s disease, but also indicating an important role of cholinergic system dysfunction for vascular dementia.

Differential amygdala activation to negative and positive emotional pictures during an indirect task

The role of the amygdala for the processing of valence and arousal is a matter of debate. Using event-related functional magnetic resonance imaging, we tested valence-specific amygdala effects during attentional distraction. Subjects attended to a matching task in the foreground of neutral pictures, and of negative and positive pictures matched for arousal. Negative pictures elicited stronger amygdala activation than neutral or positive pictures, suggesting valence-specific amygdala responses under attentional load.

Positional Brain Deformation Visualized With Magnetic Resonance Morphometry

OBJECTIVETo assess and visualize gravitational effects on brain morphology and the position of the brain within the skull by magnetic resonance (MR) morphometry in order to identify confounding effects and possible sources of error for accurate planning of neurosurgical interventions. METHODSThree-dimensional MR imaging data sets of 13 healthy adults were acquired in different positions in the scanner. With a morphometric approach, data sets were evaluated by deformation field analysis and the brain boundary shift integral. Distortions of the brain were assessed comparing right versus left and prone versus supine positioning, respectively. RESULTSTwo effects could be differentiated: 1) greatest brain deformation of up to 1.7 mm predominantly located around central brain structures in the lateral direction and a less pronounced change after position changes in posterior-anterior direction, and 2) the brain boundary shift integral depicted position-dependent brain shift relative to the inner skull. CONCLUSIONPosition-dependent effects on brain structure may undermine the accuracy of neuronavigational and other neurosurgical procedures. Furthermore, in longitudinal MR volumetric studies, gravitational effects should be kept in mind and the scanning position should be rigidly controlled for.

Detection of multiple intracranial hemorrhages in a child with acute lymphocytic leukemia (ALL) by susceptibility weighted imaging (SWI).

Susceptibility weighted imaging (SWI) combines magnitude and phase information from a high-resolution, fully velocity compensated, three-dimensional (3D) gradient echo sequence. We report on the use of this MRI technique in a young patient with acute lymphocytic leukemia (ALL) and demonstrate a higher detection rate of hemorrhagic lesion in comparison with other T2*-weighted sequences.

[Visualization of symmetric striopallidodentate calcinosis by using high-resolution susceptibility-weighted MR imaging. An account of the impact of different diagnostic methods of M. Fahr].

ZusammenfassungNeben den häufigen idiopathischen Stammganglienverkalkungen mit eher geringer Ausprägung wird insbesondere bei einer Alteration des Kalzium- und Phosphatstoffwechsels in Verbindung mit einer Dysfunktion der Nebenschilddrüsen das seltene morphologische Vollbild eines M. Fahr mit bilateralen Verkalkungen der Basalganglien, des Thalamus, des Nucleus dentatus sowie des Marklagers der Großhirnhemisphären diagnostiziert.Die morphologische Diagnosestellung eines M. Fahr erfolgt durch Abklärung mittels CT und MRT, wobei die CT eine Quantifizierung und Detektion von intrazerebralen Verkalkungen mit hoher Sensitivität erlaubt. Die MRT gewinnt bei einer klinisch-neurologischen Manifestation des M. Fahr zunehmend an Bedeutung, um eine anderweitige, nicht mit den intrazerebralen Verkalkungen in Zusammenhang stehende Genese einer klinisch-neurologischen Symptomatik auszuschließen.Die bisher verwendeten MR-Sequenzen ermöglichen nur eine limitierte Detektion der intrakraniellen Kalzifikationen und sind hinsichtlich der Bildgebung durch differierende Signalveränderungen in Abhängigkeit vom Krankheitsstadium, hinsichtlich von Unterschieden im Kalziummetabolismus und in der Zusammensetzung der Kalzifikationen gekennzeichnet. Mit Hilfe einer neuen, räumlich hochaufgelösten, suszeptibilitätsgewichteten MR-Sequenz gelingt die detaillierte Visualisierung intrazerebraler Verkalkungen, welche anhand eines Patienten mit dem Vollbild eines M. Fahr dokumentiert wird. In Ergänzung dazu werden ein Überblick hinsichtlich der für die Diagnosestellung eines M. Fahr relevanten diagnostischen Methoden vermittelt und klinische Aspekte ergänzend diskutiert.AbstractBilateral striopallidodentate calcinosis, also known as Fahr’s disease, is characterized by symmetric calcifications of the basal ganglia, thalami, dentate nuclei of the cerebellum and white matter of the cerebral hemispheres. Besides the common idiopathic etiology of bilateral intracerebral calcinosis, alterations of calcium metabolism are present in rare cases, which are especially caused by hormonal dysfunction of the parathyroids.Advanced imaging techniques, such as CT and MRI, demonstrate increasing relevance regarding diagnosis of bilateral striopallidodentate calcinosis. Intracranial calcifications are routinely observed with high sensitivity by CT. On MR images calcifications exhibit different signal intensities, which depend on the stage of the disease, differences in calcium metabolism and the compound of these calcifications. Application of a new high-resolution, susceptibility-weighted MR sequence allows detailed visualization of the intracerebral calcifications in Fahr’s disease. Further diagnostic methods and important aspects regarding clinical manifestation of bilateral striopallidodentate calcinosis are also discussed.