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Parametric tests of linear models for images modeled as random fields are based like ordinary univariate tests on distributional assumptions. It is here shown that the effect of departures from assumptions in random field tests is more pronounced than in the univariate condition. Simulations are presented investigating in detail the influence of smoothing,(More)
BACKGROUND Atomoxetine is a selective norepinephrine reuptake inhibitor clinically used for treatment of attention-deficit/hyperactivity disorder. In healthy control subjects, doses of 40 mg or 60 mg improved inhibitory control in combination with modulation of prefrontal cortex functioning. We investigated the effects of atomoxetine (80 mg) on error(More)
We discuss the assessment of signal change in single magnetic resonance images (MRI) based on quantifying significant departure from a reference distribution estimated from a large sample of normal subjects. The parametric approach is to build a test based on the expected distribution of extrema in random fields. However, in conditions where the variance is(More)
In a previous study we showed that errors following errors activate a strategic (prefrontal) mechanism. In an error trial (trial n) following an erroneous previous trial (trial n - 1) healthy control subjects were found to have enlarged (more negative) amplitudes of the error related negativity (ERN)/error negativity (Ne), an electrophysiological correlate(More)
Major depressive disorder (MDD) can be characterized by a wide-ranging profile of cognitive deficits including attention, memory, and executive functions which is possibly due to reduced volumes and a hypometabolism of the anterior cingulate cortex, orbitofrontal, and dorsolateral prefrontal cortex. We examined 21 patients with MDD in partial remission and(More)
Simple baseline studies correlate average perfusion levels measured at rest with individual variables, or contrast subject groups as in case-control studies. In this methodological work, we summarize some formal properties of the design of these studies, and investigate the sources of variance that characterize data acquired with the arterial spin labeling(More)
BACKGROUND The serotonin transporter length repeat polymorphism (5-HTTLPR) in the promoter region of the serotonin transporter gene (SLC6A4) has been associated in healthy subjects with changes in basal perfusion levels in the limbic system and ventral prefrontal areas, regions involved in the pathophysiology of depression and anxiety, suggesting the(More)
Early studies of rest cerebral metabolism and perfusion reported no association with intellectual capacity. We revisit this issue using a larger sample (N=146) and a continuous arterial spin labeling technique to measure perfusion, and working memory capacity as a measure of intellectual capacity. In the cortex, working memory capacity correlated diffusely(More)
Even in the presence of negative information, healthy human beings display an optimistic tendency when thinking of past success and future chances, giving a positive bias to everyday's cognition. The tendency to actively select positive thoughts suggests the existence of a mechanism to exclude negative content, raising the issue of its dependence on(More)
BACKGROUND Images of perfusion estimates obtained with the continuous arterial spin labelling technique are characterized by variation between single acquisitions. Little is known about the spatial determinants of this variation during the acquisition process and their impact on voxel-by-voxel estimates of effects. RESULTS We show here that the spatial(More)