Functional network topology of the right insula affects emotion dysregulation in hyperactive-impulsive attention-deficit/hyperactivity disorder

Contains fulltext : 236832.pdf (Publisher’s version ) (Open Access

Enhancing precision in human neuroscience

Human neuroscience has always been pushing the boundary of what is measurable. During the last decade, concerns about statistical power and replicability – in science in general, but also specifically in human neuroscience – have fueled an extensive debate. One important insight from this discourse is the need for larger samples, which naturally increases statistical power. An alternative is to increase the precision of measurements, which is the focus of this review. This option is often overlooked, even though statistical power benefits from increasing precision as much as from increasing sample size. Nonetheless, precision has always been at the heart of good scientific practice in human neuroscience, with researchers relying on lab traditions or rules of thumb to ensure sufficient precision for their studies. In this review, we encourage a more systematic approach to precision. We start by introducing measurement precision and its importance for well-powered studies in human neuroscience. Then, determinants for precision in a range of neuroscientific methods (MRI, M/EEG, EDA, Eye-Tracking, and Endocrinology) are elaborated. We end by discussing how a more systematic evaluation of precision and the application of respective insights can lead to an increase in reproducibility in human neuroscience

Functional interactions during the retrieval of conceptual action knowledge: an fMRI study

Impaired retrieval of conceptual knowledge for actions has been associated with lesions of left premotor, left parietal, and left middle temporal areas [Tranel, D., Kemmerer, D., Adolphs, R., Damasio, H., & Damasio, A. R. Neural correlates of conceptual knowledge for actions. Cognitive Neuropsychology, 409-432, 2003]. Here we aimed at characterizing the differential contribution of these areas to the retrieval of conceptual knowledge about actions. During functional magnetic resonance imaging (fMRI), different categories of pictograms (whole-body actions, manipulable and nonmanipulable objects) were presented to healthy subjects. fMRI data were analyzed using SPM2. A conjunction analysis of the neural activations elicited by all pictograms revealed ( p<.05, corrected) a bilateral inferior occipito-temporal neural network with strong activations in the right and left fusiform gyri. Action pictograms contrasted to object pictograms showed differential activation of area MT+, the inferior and superior parietal cortex, and the premotor cortex bilaterally. An analysis of psychophysiological interactions identified contribution-dependent changes in the neural responses when pictograms triggered the retrieval of conceptual action knowledge: Processing of action pictograms specifically enhanced the neural interaction between the right and left fusiform gyri, the right and left middle temporal cortices (MT+), and the left superior and inferior parietal cortex. These results complement and extend previous neuropsychological and neuroimaging studies by showing that knowledge about action concepts results from an increased coupling between areas concerned with semantic processing (fusiform gyrus), movement perception (MT+), and temporospatial movement control (left parietal cortex)

Nicotinergic Modulation of Attention-Related Neural Activity Differentiates Polymorphisms of DRD2 and CHRNA4 Receptor Genes

<div><p>Cognitive and neuronal effects of nicotine show high interindividual variability. Recent findings indicate that genetic variations that affect the cholinergic and dopaminergic neurotransmitter system impact performance in cognitive tasks and effects of nicotine. The current pharmacogenetic functional magnetic resonance imaging (fMRI) study aimed to investigate epistasis effects of CHRNA4/DRD2 variations on behavioural and neural correlates of visuospatial attention after nicotine challenge using a data driven partial least squares discriminant analysis (PLS-DA) approach. Fifty young healthy non-smokers were genotyped for CHRNA4 (rs1044396) and DRD2 (rs6277). They received either 7 mg transdermal nicotine or a matched placebo in a double blind within subject design prior to performing a cued target detection task with valid and invalid trials. On behavioural level, the strongest benefits of nicotine in invalid trials were observed in participants carrying both, the DRD2 T- and CHRNA4 C+ variant. Neurally, we were able to demonstrate that different DRD2/CHRNA4 groups can be decoded from the pattern of brain activity in invalid trials under nicotine. Neural substrates of interindividual variability were found in a network of attention-related brain regions comprising the pulvinar, the striatum, the middle and superior frontal gyri, the insula, the left precuneus, and the right middle temporal gyrus. Our findings suggest that polymorphisms in the CHRNA4 and DRD2 genes are a relevant source of individual variability in pharmacological studies with nicotine.</p></div

Long-Term Effects of Attentional Performance on Functional Brain Network Topology

<div><p>Individuals differ in their cognitive resilience. Less resilient people demonstrate a greater tendency to vigilance decrements within sustained attention tasks. We hypothesized that a period of sustained attention is followed by prolonged changes in the organization of “resting state” brain networks and that individual differences in cognitive resilience are related to differences in post-task network reorganization. We compared the topological and spatial properties of brain networks as derived from functional MRI data (N = 20) recorded for 6 mins before and 12 mins after the performance of an attentional task. Furthermore we analysed changes in brain topology during task performance and during the switches between rest and task conditions. The cognitive resilience of each individual was quantified as the rate of increase in response latencies over the 32-minute time course of the attentional paradigm. On average, functional networks measured immediately post-task demonstrated significant and prolonged changes in network organization compared to pre-task networks with higher connectivity strength, more clustering, less efficiency, and shorter distance connections. Individual differences in cognitive resilience were significantly correlated with differences in the degree of recovery of some network parameters. Changes in network measures were still present in less resilient individuals in the second half of the post-task period (i.e. 6–12 mins after task completion), while resilient individuals already demonstrated significant reductions of functional connectivity and clustering towards pre-task levels. During task performance brain topology became more integrated with less clustering and higher global efficiency, but linearly decreased with ongoing time-on-task. We conclude that sustained attentional task performance has prolonged, “hang-over” effects on the organization of post-task resting-state brain networks; and that more cognitively resilient individuals demonstrate faster rates of network recovery following a period of attentional effort.</p></div

Identified brain regions contributing to genotype classification.

<p>¹ Center of gravity coordinate of the clusters.</p><p>² Only clusters that exceeded the voxel extent threshold of k≥40 are reported.</p><p>³ Clusters showing increased (+) or decreased (-) BOLD levels under nicotine (p≤0.05) for each genotype group (CHRNA4 / DRD2) during invalid trials. Post-hoc tests of mean cluster BETA values; tendencies (p≤0.1) are indicated by rectangle brackets.</p><p>Identified brain regions contributing to genotype classification.</p

Visual cueing paradigm (A) and behavioural results (B).

<p><b>A.</b> Scheme of the three task conditions; valid (120), invalid (30), catch (20), and zero (50, no cue and no target, not depicted) trials were presented in randomized order with a SOA of 2000 ms. <b>B.</b> Difference of the validity effect (slowing of RTs due to invalidly cued trials as compared to valid trials) between nicotine and placebo. The CHRNA4 C+ and DRD2 T- genotype group shows a significant benefit from nicotine. The significant three-way interaction of <i>genotype group</i> x <i>treatment</i> x <i>condition</i> as displayed in the current figure was identified by post-hoc ANOVAs to be driven by the <i>genotype group</i> x <i>treatment</i> interaction during invalid trials.</p

Illustration of parcellation routine for seed region/node definition.

<p>Cortical and subcortical brain regions were parcellated into 442 brain nodes. (<b>A</b>) The parcellation routine was based on an anatomically parcellated and labeled T1 volume provided by the AAL toolbox (Tzourio-Mazoyer et al., 2002). (<b>B</b>) The parcellation routine randomly and homogenously split the larger AAL regions into 442 smaller subparcels while preserving the macro-anatomical borders as defined in the AAL-template. (<b>C</b>) This parcellation approach creates more homogenous seed region sizes as compared to the original AAL-template so that possible biasing effects of parcel sizes on functional connectivity (Salvador et al., 2008; Fornito et al., 2010) were prevented. The main statistical analyses were repeated with alternative templates in order to assure that the reported effects of the RS data analysis were not driven by a singular parcellation template (see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0074125#pone.0074125.s001" target="_blank">File S1</a>).</p