The influences of task difficulty and response correctness on neural systems supporting fluid reasoning

This functional magnetic resonance imaging (fMRI) study examined neural contributions to managing task difficulty and response correctness during fluid reasoning. Previous studies investigate reasoning by independently varying visual complexity or task difficulty, or the specific domain. Under natural conditions these factors interact in a complex manner to support dynamic combinations of perceptual and conceptual processes. This study investigated fluid reasoning under circumstances that would represent the cognitive flexibility of real life decision-making. Results from a mixed effects analysis corrected for multiple comparisons indicate involvement of cortical and subcortical areas during fluid reasoning. A 2 × 2 ANOVA illustrates activity related to variances in task difficulty correlated with increased blood oxygenation level-dependent (BOLD)-signal in the left middle frontal gyrus (BA6). Activity related to response correctness correlated with increased BOLD-signal in a larger, distributed system including right middle frontal gyrus (BA6), right superior parietal lobule (BA7), left inferior parietal lobule (BA40), left lingual gyrus (BA19), and left cerebellum (Lobule VI). The dissociation of function in left BA 6 for task difficulty and right BA6 for response correctness and the involvement of a more diffuse network involving the left cerebellum in response correctness extends knowledge about contributions of classic motor and premotor areas supporting higher level cognition

Environmental influences on neural systems of relational complexity

Constructivist learning theory contends that we construct knowledge by experience and that environmental context influences learning. To explore this principle, we examined the cognitive process relational complexity (RC), defined as the number of visual dimensions considered during problem solving on a matrix reasoning task and a well-documented measure of mature reasoning capacity. We sought to determine how the visual environment influences RC by examining the influence of color and visual contrast on RC in a neuroimaging task. To specify the contributions of sensory demand and relational integration to reasoning, our participants performed a non-verbal matrix task comprised of color, no-color line, or black-white visual contrast conditions parametrically varied by complexity (relations 0, 1, 2). The use of matrix reasoning is ecologically valid for its psychometric relevance and for its potential to link the processing of psychophysically specific visual properties with various levels of RC during reasoning. The role of these elements is important because matrix tests assess intellectual aptitude based on these seemingly context-less exercises. This experiment is a first step toward examining the psychophysical underpinnings of performance on these types of problems. The importance of this is increased in light of recent evidence that intelligence can be linked to visual discrimination. We submit three main findings. First, color and black-white visual contrast (BWVC) add demand at a basic sensory level, but contributions from color and from BWVC are dissociable in cortex such that color engages a “reasoning heuristic” and BWVC engages a “sensory heuristic.” Second, color supports contextual sense-making by boosting salience resulting in faster problem solving. Lastly, when visual complexity reaches 2-relations, color and visual contrast relinquish salience to other dimensions of problem solving

Lovastatin regulates brain spontaneous low-frequency brain activity in Neurofibromatosis type 1

Item does not contain fulltextIn the Neurofibromatosis type 1 (NF1) mouse model, lovastatin, used clinically for hypercholesterolemia, improves cognitive dysfunction. While such impairment has been studied in NF1, the neural substrates remain unclear. The aim of this imaging add-on to a Phase 1 open-label trial was to examine the effect of lovastatin on Default Network (DN) resting state functional connectivity (RSFC). Seven children with NF1 (aged 11.9 +/- 2.2; 1 female) were treated with lovastatin once daily for 12 weeks. A 7-min 3-T echo-planar-imaging scan was collected one day before beginning treatment (off-drug) and the last day of treatment (on-drug) while performing a flanker task. After regressing-out task-associated variance, we used the residual time series as "continuous resting-state data" for RSFC analyses using 11 DN regions of interest. For qualitative comparisons, we included a group of 19 typically developing children (TDC) collected elsewhere. In the on-drug condition, lovastatin increased long-range positive RSFC within DN core regions (i.e., anterior medial prefrontal cortex and posterior cingulate cortex, PCC). In addition, lovastatin produced less diffuse local RSFC in the dorsomedial prefrontal cortex and PCC. The pattern of RSFC observed in the NF1 participants when on-drug closely resembled the RSFC patterns exhibited by the TDC. Lovastatin administration in this open trial regulated anterior-posterior long-range and local RSFC within the DN. These preliminary results are consistent with a role for lovastatin in normalization of developmental processes and with apparent benefits in a mouse NF1 model