Science posts

See science posts on page 16 below.

    • 2010
    • Nancy A. Dennis et al.
    • COMT Val108/158 Met Genotype Affects Neural but not Cognitive Processing in Healthy Individuals
    • The relationship between cognition and a functional polymorphism in the catechol-O-methlytransferase (COMT) gene, val108/158met, is one of debate in the literature. Furthermore, based on the dopaminergic differences associated with the COMT val108/158met genotype, neural differences during cognition may be present, regardless of genotypic differences in cognitive performance. To investigate these issues the current study aimed to 1) examine the effects of COMT genotype using a large sample of healthy individuals (n = 496–1218) and multiple cognitive measures, and using a subset of the sample (n = 22), 2) examine whether COMT genotype effects medial temporal lobe (MTL) and frontal activity during successful relational memory processing, and 3) investigate group differences in functional connectivity associated with successful relational memory processing. Results revealed no significant group difference in cognitive performance between COMT genotypes in any of the 19 cogniti..
    • 2015
    • Jonas Richiardi et al.
    • Correlated gene expression supports synchronous activity in brain networks
    • During rest, brain activity is synchronized between different regions widely distributed throughout the brain, forming functional networks. However, the molecular mechanisms supporting functional connectivity remain undefined. We show that functional brain networks defined with resting-state functional magnetic resonance imaging can be recapitulated by using measures of correlated gene expression in a post mortem brain tissue data set. The set of 136 genes we identify is significantly enriched for ion channels. Polymorphisms in this set of genes significantly affect resting-state functional connectivity in a large sample of healthy adolescents. Expression levels of these genes are also significantly associated with axonal connectivity in the mouse. The results provide convergent, multimodal evidence that resting-state functional networks correlate with the orchestrated activity of dozens of genes linked to ion channel activity and synaptic function.
    • 2010
    • Anastasia Christakou et al.
    • Maturation of limbic corticostriatal activation and connectivity associated with developmental changes in temporal discounting
    • Temporal discounting (TD) matures with age, alongside other markers of increased impulse control, and coherent, self-regulated behaviour. Discounting paradigms quantify the ability to refrain from preference of immediate rewards, in favour of delayed, larger rewards. As such, they measure temporal foresight and the ability to delay gratification, functions that develop slowly into adulthood. We investigated the neural maturation that accompanies the previously observed age-related behavioural changes in discounting, from early adolescence into mid-adulthood. We used functional magnetic resonance imaging of a hypothetical discounting task with monetary rewards delayed in the week to year range. We show that age-related reductions in choice impulsivity were associated with changes in activation in ventromedial prefrontal cortex (vmPFC), anterior cingulate cortex (ACC), ventral striatum (VS), insula, inferior temporal gyrus, and posterior parietal cortex. Limbic frontostriatal activatio..
    • 2009
    • Erie D. Boorman et al.
    • How Green Is the Grass on the Other Side? Frontopolar Cortex and the Evidence in Favor of Alternative Courses of Action
    • Behavioral flexibility is the hallmark of goal-directed behavior. Whereas a great deal is known about the neural substrates of behavioral adjustment when it is explicitly cued by features of the external environment, little is known about how we adapt our behavior when such changes are made on the basis of uncertain evidence. Using a Bayesian reinforcement-learning model and fMRI, we show that frontopolar cortex (FPC) tracks the relative advantage in favor of switching to a foregone alternative when choices are made voluntarily. Changes in FPC functional connectivity occur when subjects finally decide to switch to the alternative behavior. Moreover, interindividual variation in the FPC signal predicts interindividual differences in effectively adapting behavior. By contrast, ventromedial prefrontal cortex (vmPFC) encodes the relative value of the current decision. Collectively, these findings reveal complementary prefrontal computations essential for promoting short- and long-term be..
    • 2008
    • Justin L. Vincent et al.
    • Evidence for a Frontoparietal Control System Revealed by Intrinsic Functional Connectivity
    • Two functionally distinct, and potentially competing, brain networks have been recently identified that can be broadly distinguished by their contrasting roles in attention to the external world versus internally directed mentation involving long-term memory. At the core of these two networks are the dorsal attention system and the hippocampal-cortical memory system, a component of the brain's default network. Here spontaneous blood-oxygenation-level-dependent (BOLD) signal correlations were used in three separate functional magnetic resonance imaging data sets (n = 105) to define a third system, the frontoparietal control system, which is spatially interposed between these two previously defined systems. The frontoparietal control system includes many regions identified as supporting cognitive control and decision-making processes including lateral prefrontal cortex, anterior cingulate cortex, and inferior parietal lobule. Detailed analysis of frontal and parietal cortex, including ..
    • 2015
    • Chobok Kim et al.
    • The role of the frontopolar cortex in manipulation of integrated information in working memory
    • Cognitive operations often require integration of information. Previous studies have shown that, integration of information in working memory recruits frontopolar cortex (FPC). In this fMRI study, we sought to reveal neural mechanisms of FPC underlying the integration of information during arithmetic tasks. We compared a condition requiring manipulation of two features of an item held in working memory with manipulation of one feature. The results showed that, FPC was equally recruited in both conditions, while dorsolateral prefrontal cortex (DLPFC) tended to be more activated when manipulating two features. We suggest that, FPC plays an integrative role and is recruited by the production of representations in accordance with task constraints, whereas DLPFC appears to be sensitive to processing demands induced by the manipulation of information.
    • 2015
    • Brunyé, Tad T. et al.
    • Increasing breadth of semantic associations with left frontopolar direct current brain stimulation: a role for individual differences
    • The aim of this study was to evaluate the influence of left frontopolar versus auditory (control) cortex transcranial direct current stimulation (tDCS) on the breadth of semantic associations produced in a cued free association task. A within-participants design administered anodal tDCS over the left frontopolar or auditory cortex, centered at electrode site AFZ or T7 using a 4×1 targeted stimulation montage. During stimulation, participants produced free associates in response to cues designed to promote narrow, moderate, or broad semantic associations. We measured the latent semantic associative strength of generated words relative to cues. The cue manipulation produced expected effects on the associative breadth of generated words, but there was no main effect of stimulation site, and calculated Bayes factors showed strong support for the null hypothesis. However, individual differences in creative potential, as assessed by the remote associates test, reliably and positi..
    • 2015
    • Philippe Domenech et al.
    • Executive control and decision-making in the prefrontal cortex
    • The prefrontal cortex (PFC) subserves decision-making and executive control. Here we review recent empirical and modeling works with a focus on neuroimaging studies, which start unifying these two conceptual approaches of PFC function. We propose that the PFC comprises two arbitration systems: (1) a peripheral system comprising premotor/caudal PFC regions and orbitofrontal regions involved in the selection of actions based on perceptual cues and reward values, respectively, and embedded in behavioral sets associated with external contingencies inferred as being stable; (2) a core system comprising ventromedial, dorsomedial, lateral and polar PFC regions involved in superordinate probabilistic reasoning for arbitrating online between exploiting/adjusting previously learned behavioral sets and exploring/creating new ones for efficient adaptive behavior in variable and open-ended environments.
    • 2015
    • Naama Mayseless et al.
    • Generating original ideas: The neural underpinning of originality
    • One of the key aspects of creativity is the ability to produce original ideas. Originality is defined in terms of the novelty and rarity of an idea and is measured by the infrequency of the idea compared to other ideas. In the current study we focused on divergent thinking (DT) – the ability to produce many alternate ideas – and assessed the neural pathways associated with originality. Considering that generation of original ideas involves both the ability to generate new associations and the ability to overcome automatic common responses, we hypothesized that originality would be associated with activations in regions related to associative thinking, including areas of the default mode network (DMN) such as medial prefrontal areas, as well as with areas involved in cognitive control and inhibition. Thirty participants were scanned while performing a DT task that required the generation of original uses for common objects. The results indicate that the ability to produce ..
    • 2014
    • Annukka K. Lindell
    • On the interrelation between reduced lateralization, schizotypy, and creativity
    • Genius and madness have long been thought to be intimately entwined. However, the idea remains controversial: some rail against the stereotype of the mad scientist or the crazy artist (e.g., Schlesinger, 2009, 2012), while others note higher incidences of mental illness amongst creative geniuses, including prize-winning authors, visual artists, and poets (e.g., Andreasen, 1987; Kaufman, 2000-2001; Nettle, 2006). Consistent with early ideas of a shared genetic basis (e.g., Lombroso, 1891; Galton, 1892), a growing body of research highlights a positive correlation between mental illness and heightened creativity (e.g., Rothenberg, 2001). The relationship between creativity and schizotypy warrants close examination, as greater creativity is associated with higher levels of schizotypal traits (e.g., Folley and Park, 2005). Atypical brain lateralization may play the causal role, being evident in people who are highly creative and in people who have high levels of schizotypal traits (e.g.,..

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