Medial prefrontal cortex serotonin 1A and 2A receptor binding interacts to predict threat-related amygdala reactivity

Background\ud The amygdala and medial prefrontal cortex (mPFC) comprise a key corticolimbic circuit that helps shape individual differences in sensitivity to threat and the related risk for psychopathology. Although serotonin (5-HT) is known to be a key modulator of this circuit, the specific receptors mediating this modulation are unclear. The colocalization of 5-HT1A and 5-HT2A receptors on mPFC glutamatergic neurons suggests that their functional interactions may mediate 5-HT effects on this circuit through top-down regulation of amygdala reactivity. Using a multimodal neuroimaging strategy in 39 healthy volunteers, we determined whether threat-related amygdala reactivity, assessed with blood oxygen level-dependent functional magnetic resonance imaging, was significantly predicted by the interaction between mPFC 5-HT1A and 5-HT2A receptor levels, assessed by positron emission tomography.\ud \ud Results\ud 5-HT1A binding in the mPFC significantly moderated an inverse correlation between mPFC 5-HT2A binding and threat-related amygdala reactivity. Specifically, mPFC 5-HT2A binding was significantly inversely correlated with amygdala reactivity only when mPFC 5-HT1A binding was relatively low.\ud \ud Conclusions\ud Our findings provide evidence that 5-HT1A and 5-HT2A receptors interact to shape serotonergic modulation of a functional circuit between the amygdala and mPFC. The effect of the interaction between mPFC 5-HT1A and 5-HT2A binding and amygdala reactivity is consistent with the colocalization of these receptors on glutamatergic neurons in the mPFC

Exploration of Shared Genetic Architecture Between Subcortical Brain Volumes and Anorexia Nervosa

In MRI scans of patients with anorexia nervosa (AN), reductions in brain volume are often apparent. However, it is unknown whether such brain abnormalities are influenced by genetic determinants that partially overlap with those underlying AN. Here, we used a battery of methods (LD score regression, genetic risk scores, sign test, SNP effect concordance analysis, and Mendelian randomization) to investigate the genetic covariation between subcortical brain volumes and risk for AN based on summary measures retrieved from genome-wide association studies of regional brain volumes (ENIGMA consortium, n = 13,170) and genetic risk for AN (PGC-ED consortium, n = 14,477). Genetic correlations ranged from − 0.10 to 0.23 (all p > 0.05). There were some signs of an inverse concordance between greater thalamus volume and risk for AN (permuted p = 0.009, 95% CI: [0.005, 0.017]). A genetic variant in the vicinity of ZW10, a gene involved in cell division, and neurotransmitter and immune system relevant genes, in particular DRD2, was significantly associated with AN only after conditioning on its association with caudate volume (pFDR = 0.025). Another genetic variant linked to LRRC4C, important in axonal and synaptic development, reached significance after conditioning on hippocampal volume (pFDR = 0.021). In this comprehensive set of analyses and based on the largest available sample sizes to date, there was weak evidence for associations between risk for AN and risk for abnormal subcortical brain volumes at a global level (that is, common variant genetic architecture), but suggestive evidence for effects of single genetic markers. Highly powered multimodal brain- and disorder-related genome-wide studies are needed to further dissect the shared genetic influences on brain structure and risk for AN

Berufliche Frauenfoerderung auf lokaler Ebene Materialien und Analysen zu einem Politikfeld am Beispiel der Region Ostfriesland

IAB-96-230-22 BA 827 / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

Terahertz performance of quasioptical front-ends with a hot-electron bolometer

We present terahertz performance of quasioptical front-ends consisting of a hot-electron bolometer imbedded in a planar feed antenna and integrated with an immersion lens. The impedance and radiation pattern of the log-spiral and double-slot planar feeds are evaluated using the method of moments; the collimating action of the lens is modelled using the physical optics. The total efficiency of the front-ends is computed taking into account frequency dependent impedance of the bolometer. Measured performance of the front-ends qualifies the simulation technique as a reliable tool for the design of terahertz receivers

Integrated Planar Antennas at Terahertz Waves

We present the terahertz performance of integrated lens antennas consisting of a double-slot or a log-spiral planar feed and a synthesized elliptical lens. The radiation pattern and the impedance of the planar feeds are computed using the method of moments; the collimating action of the lens is modeled using the physical-optics approach based on the Huygens principle. In the frequency range from 1.5 to 3 THz (double-slot feed) and 0.6 to 5 THz (log-spiral feed) the measured antenna efficiency and radiation pattern correspond fairly well with the results of simulations approving this simulation technique as a reliable tool for the antenna design

Integrated planar log-spiral antenna at terahertz waves

We present terahertz performance of integrated lens antennas consisting of a complementary log-spiral planar feed and a synthesized elliptical lens. The radiation pattern and the impedance of the planar feed are computed using the method of moments; the action of the lens is evaluated using the physical-optics approach based on the Huygens principle. In the frequency range from 0.6 to 5 THz measured antenna efficiency and radiation pattern correspond fairly well with the results of simulations approving this simulation technique as a reliable tool for the antenna design

Terahertz performance of integrated double-slot antennas

We present the terahertz performance of integrated lens antennas consisting of a double-slot planar feed antenna and a synthesized elliptical lens. The radiation pattern and the impedance of the planar feed are computed using the method of moments; the collimating action of the lens is modeled using the physical-optics approach based on the Huygens principle. In the frequency range from 1.5 to 3 THz the measured antenna efficiency and radiation pattern correspond fairly well with the results of simulations approving this simulation technique as a reliable tool for the antenna design

A 4.7-THz gas laser local oscillator for GREAT on SOFIA

A particularly important transition for astronomy is the OI fine structure line at 4.7 THz. It is an important cooling line of the interstellar medium and allows studying the chemical composition, the evolution, and the dynamical behavior of astronomical objects. Consequently, this transition is a main target to be observed with GREAT, the German Receiver for Astronomy at Terahertz Frequencies, which will be operated on board of SOFIA. A major challenge for a heterodyne receiver operating at such a high frequency is the local oscillator (LO). Despite significant progress in the development of a quantum-cascade laser based LO [1] the baseline design for GREAT is an optically pumped gas laser operated at 4.7 THz. In this report we will present the design and performance of the 4.7-THz gas laser LO for SOFIA. The LO is based on a radio frequency excited CO2 laser which has a sealed-off gas volume and which is frequency tunable by a grating. The CO2 laser is operated on the 9P12 transition of the CO2 molecule. The output emission is focused into the THz laser resonator. The THz laser is transversely excited. It operates on the 4.75 THz line of 13CH3OH. For frequency stabilization of the CO2 laser a small part of its output radiation is guided into a Fabry-Pérot interferometer (FPI) which serves as a length or frequency reference. In order to compensate for temperature or pressure induced drifts of the FPI length the emission of a frequency stabilized a helium-neon (HeNe) laser is coupled into the FPI as well. The FPI is locked to the emission of the HeNe laser. We will present the design and the performance of the LO with respect to output power, short and long term power stability, and beam profile. The system is ready and awaits implementation in GREAT and operation on board of SOFIA