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Previous studies hypothesized that neurodevelopmental risk factors may play a role in the pathogenesis of obsessive-compulsive disorder (OCD). Cortical folding has been shown to be a reliable indicator for normal and altered neurodevelopment, but in OCD it has barely been investigated up to now. The present study investigates whether alterations in gyrification are detectable in OCD and, if so, how these are associated with clinical characteristics.
We compared the local Gyrification Index (lGI) between 75 OCD patients and 75 matched healthy subjects across the whole brain. In addition, for those regions exhibiting an altered lGI in patients we explored a potential relationship to symptom severity, age of onset, and influence of medication.
OCD patients had a significantly decreased lGI in right parietal, precentral but also insula, temporal, pars triangularis and rostral middle frontal regions compared to healthy subjects. A positive association with age of onset was found but no association with symptom severity. There was no effect of co-morbidity or medication.
The reduced gyrification found in OCD confirms previous findings in other psychiatric disorders and suggests that alterations may already occur during early stages of brain development. Our findings support the idea that altered cortical folding might represent a trait characteristic of the disorder although longitudinal studies are needed to clarify the trajectory of this morphological measure in OCD.
We present the adaptive optics assisted, near-infrared VLTI instrument GRAVITY for precision narrow-angle astrometry and interferometric phase referenced imaging of faint objects. With its two fibers per telescope beam, its internal wavefront sensors and fringe tracker, and a novel metrology concept, GRAVITY will not only push the sensitivity far beyond what is offered today, but will also advance the astrometric accuracy for UTs to 10 μas. GRAVITY is designed to work with four telescopes, thus providing phase referenced imaging and astrometry for 6 baselines simultaneously. Its unique capabilities and sensitivity will open a new window for the observation of a wide range of objects, and — amongst others — will allow the study of motion within a few times the event horizon size of the Galactic Center black hole.
MIRI, the mid-IR instrument of JWST (James Webb Space Telescope),
will include a coronagraphic device for which the ultimate goal is
the detection and caracterization of extrasolar planets around
nearby stars. In this paper, we describe the optical concept of
MIRI and the instrumental choices that were made in phase A and B
regarding the coronagraphic system. Finally, we will present
numerical simulations that we carried out to evaluate the
capability for detecting extrasolar giant gazeous planets.
We report on the facility we developed at the Observatoire de Meudon to test the Four Quadrant Phase Mask (4QPM) coronagraph in the Infrared (IR) and at low temperature. This facility has been developed
in the context of the mid-IR instrument MIRI for the James Webb Space Telescope. Three 4QPM will take
place inside MIRI and need to be qualified for space environment. The performance of the coronagraph is
in agreement with our expectations from numerical simulations. The peak intensity of the diffraction pattern is reduced by a factor 380, a performance being limited by the chromatic effects and the size
of the bench source.
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