Evidence of validity in a new method for measurement of dexterity in children and adolescents.

Aim: many everyday activities involve manipulation of objects with the fingertips. Impaired performance in manipulative tasks is common in neurodevelopmental disorders. Thus accurate assessment of an individual's ability to coordinate fingertip forces is important for planning treatment.

A prefrontal non-opioid mechanism in placebo analgesia.

Behavioral studies have suggested that placebo analgesia is partly mediated by the endogenous opioid system. Expanding on these results we have shown that the opioid-receptor-rich rostral anterior cingulate cortex (rACC) is activated in both placebo and opioid analgesia. However, there are also differences between the two treatments.

Measuring working memory capacity with greater precision in the lower capacity ranges.

Working memory capacity is usually measured as the number of stimuli correctly remembered. However, these measures lack precision when assessing individuals with low capacity. This study aimed to create a more precise measure of visuospatial working memory capacity, using intra-level differences in difficulty between items.

Dopamine D2 receptor density in the limbic striatum is related to implicit but not explicit movement sequence learning.

A large body of literature suggests that motor sequence learning involves dopamine-modulated plastic processes in the basal ganglia. Sequence learning can occur both implicitly, without conscious awareness and intention to learn, and explicitly, i.e.

The dopamine system in idiopathic generalized epilepsies: identification of syndrome-related changes.

The present study tests the hypothesis that the dopamine system is altered in idiopathic generalized epilepsy (IGE), and that the pattern of possible changes differs between juvenile myoclonic epilepsy (JME) and epilepsy with tonic-clonic seizures only (GTCS). The dopamine (DA) system was investigated with PET and a DA transporter (DAT) ligand [(11)C]PE2I in 13 patients with JME, 13 with GTCS, and 12 healthy controls. The binding potential (BP) to DAT was quantified in the caudate, putamen, and midbrain.

PET studies of D2-receptor binding in striatal and extrastriatal brain regions: Biochemical support in vivo for separate dopaminergic systems in humans.

Most molecular imaging studies of the dopamine (DA) system performed to date have focused on the striatum, a region receiving dense dopaminergic innervation. In clinical research on the DA D2-receptor, striatal binding has often been regarded as an index of global DA function, based on the underlying assumption of common regulatory mechanisms for receptor expression across brain regions. Recent data has challenged this view, suggesting differences in genetic regulation between striatal and extrastriatal brain regions.

Androstenol--a steroid derived odor activates the hypothalamus in women.

Background: Whether pheromone signaling exists in humans is still a matter of intense discussion. In the present study we tested if smelling of Androstenol, a steroid produced by the human body and reported to affect human behavior, may elicit cerebral activation. A further issue was to evaluate whether the pattern of activation resembles the pattern of common odors.

Amygdala-dependent fear conditioning in humans is modulated by the BDNFval66met polymorphism.

The brain-derived neurotrophic factor (BDNF) is critically involved in neuroplasticity, as well as the acquisition, consolidation, and retention of hippocampal- and amygdala-dependent learning. A common functional A-->G single nucleotide polymorphism (BDNFval66met) in the prodomain of the human BDNF gene is associated with abnormal intracellular trafficking and reduced activity-dependent BDNF release. We studied the effect of BDNFval66met in an aversive differential fear conditioning, and a delayed extinction paradigm in 57 healthy participants.

Age-related reduction in dopamine D1 receptors in the human brain: from late childhood to adulthood, a positron emission tomography study.

Age-dependent decrease in dopamine receptor density throughout adulthood is well described, meanwhile less is known about development of dopamine system in humans and in vivo it has not been investigated. We examined dopamine D1 receptor (D1DR) binding in the cerebral cortex and striatum of 12 adolescents (mean age 13.5+/-1.

Measured motion: searching for simplicity in spinal locomotor networks.

Spinal interneurons are organized into networks that control the activity and output of the motor system. This review outlines recent progress in defining the rules that govern the assembly and function of spinal motor networks, focusing on three main areas. We first examine how subtle variations in the wiring diagrams and organization of locomotor networks in different vertebrates permits animals to adapt their motor programs to the demands of their physical environment.

Genetic variation in the serotonin transporter gene (5-HTTLPR, rs25531) influences the analgesic response to the short acting opioid Remifentanil in humans.

Background: There is evidence from animal studies that serotonin (5-HT) can influence the antinociceptive effects of opioids at the spinal cord level. Therefore, there could be an influence of genetic polymorphisms in the serotonin system on individual variability in response to opioid treatment of pain. The serotonin transporter (5-HTT) is a key regulator of serotonin metabolism and availability and its gene harbors several known polymorphisms that are known to affect 5-HTT expression (e.

Increased sensitivity to thermal pain following a single opiate dose is influenced by the COMT val(158)met polymorphism.

Increased pain sensitivity after opioid administration (opioid-induced hyperalgesia) and/or repeated painful stimuli is an individually varying and clinically important phenomenon. The functional polymorphism (val(158)met) of the Catechol-O-methyltransferase (COMT) gene regulates the metabolism of dopamine/noradrenaline. Individuals homozygous for the met(158) allele have been reported to have increased pain sensitivity and there are findings of lower micro-opioid system activation during sustained pain.

Spontaneous brain activity in the newborn brain during natural sleep--an fMRI study in infants born at full term.

Recent progress in functional neuroimaging research has provided the opportunity to probe at the brain's intrinsic functional architecture. Synchronized spontaneous neuronal activity is present in the form of resting-state networks in the brain even in the absence of external stimuli. The objective of this study was to investigate the presence of resting-state networks in the unsedated infant brain born at full term.

Advancement in PET quantification using 3D-OP-OSEM point spread function reconstruction with the HRRT.

Purpose: Image reconstruction including the modelling of the point spread function (PSF) is an approach improving the resolution of the PET images. This study assessed the quantitative improvements provided by the implementation of the PSF modelling in the reconstruction of the PET data using the High Resolution Research Tomograph (HRRT).

Methods: Measurements were performed on the NEMA-IEC/2001 (Image Quality) phantom for image quality and on an anthropomorphic brain phantom (STEPBRAIN).

Evidence of dysfunctional pain inhibition in Fibromyalgia reflected in rACC during provoked pain.

Over the years, many have viewed Fibromyalgia syndrome (FMS) as a so-called "functional disorder" and patients have experienced a concomitant lack of interest and legitimacy from the medical profession. The symptoms have not been explained by peripheral mechanisms alone nor by specific central nervous system mechanisms. In this study, we objectively evaluated the cerebral response to individually calibrated pain provocations of a pain-free body region (thumbnail).

Pheromone signal transduction in humans: what can be learned from olfactory loss.

Because humans seem to lack neuronal elements in the vomeronasal organ (VNO), many scientists believe that humans are unable to detect pheromones. This view is challenged by the observations that pheromone-like compounds, 4,16-androstadien-3-one (AND) and oestra-1,3,5(10),16-tetraen-3-ol (EST), activate the human hypothalamus. Whether these activations are mediated via VNO, venous blood or olfactory mucosa is presently unknown.

Changes in cortical dopamine D1 receptor binding associated with cognitive training.

Working memory is a key function for human cognition, dependent on adequate dopamine neurotransmission. Here we show that the training of working memory, which improves working memory capacity, is associated with changes in the density of cortical dopamine D1 receptors. Fourteen hours of training over 5 weeks was associated with changes in both prefrontal and parietal D1 binding potential.

Serotonin transporter genotype is associated with cognitive performance but not regional 5-HT1A receptor binding in humans.

The human serotonin transporter (5-HTT) gene is one of the most extensively studied in psychiatry. A functional polymorphism in the promoter region of the 5-HTT gene (5-HTTLPR) has been associated with several psychiatric disorders as well as anxiety-related personality traits. In search of a mechanistic understanding of the functional implications of 5-HTTLPR, the influence of this polymorphism on regional 5-HT1A receptor density has previously been examined in two positron emission tomography (PET) studies in humans, yielding, however, contradictory results.

Training and transfer effects of executive functions in preschool children.

Executive functions, including working memory and inhibition, are of central importance to much of human behavior. Interventions intended to improve executive functions might therefore serve an important purpose. Previous studies show that working memory can be improved by training, but it is unknown if this also holds for inhibition, and whether it is possible to train executive functions in preschoolers.

High fetal testosterone and sexually dimorphic cerebral networks in females.

Active masculinization by fetal testosterone is believed to be a major factor behind sex differentiation of the brain. We tested this hypothesis in a 15O-H2O positron emission tomography study of 11 women with congenital adrenal hyperplasia (CAH), a condition with high fetal testosterone, and 26 controls. Two indices of cerebral dimorphism were measured--functional connectivity and cerebral activation by 2 putative pheromones (androstadienone [AND] and estratetraenol [EST]), previously reported to activate the hypothalamic networks in a sex-differentiated manner.

Molecular imaging of the 5-HT(1A) receptor in relation to human cognition.

Animal studies and pharmacological studies in man have suggested that the serotonin 5-HT(1A) receptor may serve as a biomarker for cognitive functioning and a target for treatment of cognitive impairment. Consistent findings in man have nonetheless hitherto remained sparse. Positron emission tomography (PET) imaging of the 5-HT(1A) receptor in patients with Alzheimer's disease, schizophrenia and depression implicate an alteration in 5-HT(1A) receptor binding compared to control subjects, but it is yet unknown whether these alterations are related to the cognitive impairment associated with these disorders.

The precuneus/posterior cingulate cortex plays a pivotal role in the default mode network: Evidence from a partial correlation network analysis.

Recent research has shown that intrinsic brain activity as observed by functional magnetic resonance imaging (fMRI) manifest itself as coherent signal changes in networks encompassing brain regions that span long-range neuronal pathways. One of these networks, the so called default mode network, has become the primary target in recent investigations to link intrinsic activity to cognition and how intrinsic signal changes may be altered in disease. In this study we assessed functional connectivity within the default mode network during both rest and a continuous working memory task on a region-by-region basis using partial correlation analysis, a data-driven method that provides insight into effective connectivity within neuronal networks.

Common and unique components of inhibition and working memory: an fMRI, within-subjects investigation.

Behavioural findings indicate that the core executive functions of inhibition and working memory are closely linked, and neuroimaging studies indicate overlap between their neural correlates. There has not, however, been a comprehensive study, including several inhibition tasks and several working memory tasks, performed by the same subjects. In the present study, 11 healthy adult subjects completed separate blocks of 3 inhibition tasks (a stop task, a go/no-go task and a flanker task), and 2 working memory tasks (one spatial and one verbal).

Instruction effects in implicit artificial grammar learning: a preference for grammaticality.

Human implicit learning can be investigated with implicit artificial grammar learning, a paradigm that has been proposed as a simple model for aspects of natural language acquisition. In the present study we compared the typical yes-no grammaticality classification, with yes-no preference classification. In the case of preference instruction no reference to the underlying generative mechanism (i.

PET and MRI show differences in cerebral asymmetry and functional connectivity between homo- and heterosexual subjects.

Cerebral responses to putative pheromones and objects of sexual attraction were recently found to differ between homo- and heterosexual subjects. Although this observation may merely mirror perceptional differences, it raises the intriguing question as to whether certain sexually dimorphic features in the brain may differ between individuals of the same sex but different sexual orientation. We addressed this issue by studying hemispheric asymmetry and functional connectivity, two parameters that in previous publications have shown specific sex differences.