Suboptimal decision making by children with ADHD in the face of risk: Poor risk adjustment and delay aversion rather than general proneness to taking risks.

Objective: Suboptimal decision making in the face of risk (DMR) in children with attention-deficit hyperactivity disorder (ADHD) may be mediated by deficits in a number of different neuropsychological processes. We investigated DMR in children with ADHD using the Cambridge Gambling Task (CGT) to distinguish difficulties in adjusting to changing probabilities of choice outcomes (so-called risk adjustment) from general risk proneness, and to distinguish these 2 processes from delay aversion (the tendency to choose the least delayed option) and impairments in the ability to reflect on choice options. Based on previous research, we predicted that suboptimal performance on this task in children with ADHD would be primarily relate to problems with risk adjustment and delay aversion rather than general risk proneness.

Performance Monitoring in Medication-Naïve Children with Tourette Syndrome.

Background: Tourette syndrome (TS) is a childhood-onset neurodevelopmental disorder and its impact on cognitive development needs further study. Evidence from neuropsychological, neuroimaging and electrophysiological studies suggests that the decline in tic severity and the ability to suppress tics relate to the development of self-regulatory functions in late childhood and adolescence. Hence, tasks measuring performance monitoring might provide insight into the regulation of tics in children with TS.

Reduced error signalling in medication-naive children with ADHD: associations with behavioural variability and post-error adaptations.

Background: We examined the blood-oxygen level-dependent (BOLD) activation in brain regions that signal errors and their association with intraindividual behavioural variability and adaptation to errors in children with attention-deficit/hyperactivity disorder (ADHD).

Methods: We acquired functional MRI data during a Flanker task in medication-naive children with ADHD and healthy controls aged 8-12 years and analyzed the data using independent component analysis. For components corresponding to performance monitoring networks, we compared activations across groups and conditions and correlated them with reaction times (RT).

The influence of glutamatergic antagonism on motor variability, and comparison to findings in schizophrenia patients.

Objective: The primary aim of this explorative study was to investigate the influence of the glutamatergic N-methyl-d-aspartate (NMDA) receptor antagonist memantine on motor activity in healthy subjects. Secondarily, we wanted to compare these data to findings in a sample of schizophrenia patients.

Methods: The healthy subjects acted as their own controls in an open-within-subject design.

Alcohol-induced changes in cerebral blood flow and cerebral blood volume in social drinkers.

Aims: Although it is known that alcohol has vasoactive properties, previous studies have not investigated the relationship between cerebral blood flow (CBF) and cerebral blood volume (CBV) after alcohol consumption. The aim of this study was to investigate effects of alcohol on CBF and CBV, both globally and regionally, in social drinkers.

Methods: The method of choice was dynamic susceptibility contrast magnetic resonance imaging (DSC-MRI).

A forced-attention dichotic listening fMRI study on 113 subjects.

We report fMRI and behavioral data from 113 subjects on attention and cognitive control using a variant of the classic dichotic listening paradigm with pairwise presentations of consonant-vowel syllables. The syllable stimuli were presented in a block-design while subjects were in the MR scanner. The subjects were instructed to pay attention to and report either the left or right ear stimulus.

A 1H-MR spectroscopy study of changes in glutamate and glutamine (Glx) concentrations in frontal spectra after administration of memantine.

Glutamate is the major excitatory neurotransmitter in the brain and therefore important for cognitive functions. The aim of the study was to investigate if administration of the N-methyl-D-aspartate receptor antagonist memantine to healthy individuals would affect brain activation when performing an auditory attention task. The task was a variant of a dichotic listening task with different instructions that tap demands for attention and cognitive control.

The effects of the glutamate antagonist memantine on brain activation to an auditory perception task.

Glutamate is critically involved in the regulation of cognitive functions in humans. There is, however, sparse evidence regarding how blocking glutamate action at the receptor site during a cognitive task affects brain activation. In the current study, the effects of the glutamate antagonist memantine were examined with functional magnetic resonance imaging (fMRI).

Evidence for glutamatergic neurotransmission in cognitive control in an auditory attention task.

There is little knowledge regarding the underlying mediating factors for cognitive control at the synaptic level, especially the role played by glutamatergic neurotransmission. In the current study the effect of the NMDA receptor antagonist memantine was examined in a pharmacological fMRI study. Thirty-one healthy adults were scanned twice in a counter-balanced design, either drug naïve or after administration of memantine for 21 days, to build up a steady-state plasma concentration in all participants.

Auditory hallucinations in schizophrenia: the role of cognitive, brain structural and genetic disturbances in the left temporal lobe.

In this article we review research in our laboratory on auditory hallucinations using behavioral and MRI measure. The review consists of both previously published and new data that for the first time is presented together in a cohesive way. Auditory hallucinations are among the most common symptoms in schizophrenia, affecting more than 70% of the patients.