Neuroscience
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Previous research has demonstrated that aerobic exercise has disparate effects on speed of processing and movement execution. In simple and choice reaction tasks, aerobic exercise appears to increase speed of movement execution while speed of processing is unaffected. In the flanker task, aerobic exercise has been shown to reduce response time on incongruent trials more than congruent trials, purportedly reflecting a selective influence on speed of processing related to cognitive control. ⋯ Reaction time during incongruent flanker trials decreased over time in both an aerobic exercise and non-exercise control condition indicating it was not specifically influenced by exercise. This disparate influence of aerobic exercise on movement time and reaction time indicates the importance of partitioning response time when examining the influence of aerobic exercise on speed of processing. The decrease in reaction time over time independent of aerobic exercise indicates that interpreting pre-to-post exercise changes in behavior requires caution.
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The main objective of the present study was to identify markers of neural deficits in children with central auditory processing disorder (CAPD) by measuring latency and amplitude of the auditory cortical responses and mismatch negativity (MMN) responses. Passive oddball paradigms were used with nonverbal and verbal stimuli to record cortical auditory-evoked potentials and MMN. Twenty-three children aged 9-12 participated in the study: 10 with normal hearing acuity as well as CAPD and 13 with normal hearing without CAPD. ⋯ Moreover, electrode position affected the results in the same manner for both groups of children. The findings of the present study suggest that the N2 response could be a marker of neural deficits in children with CAPD. N2 results suggest that maturational factors or a different mechanism could be involved in processing auditory information at the central level for these children.
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Resting state networks' (RSNs) architecture is well delineated in mature brain, but our understanding of their development remains limited. Particularly, there are few longitudinal studies. Besides, all existing evidence is obtained using functional magnetic resonance imaging (fMRI) and there are no data on electrophysiological correlates of RSN maturation. ⋯ In line with existing fMRI evidence, both cross-sectional comparison with adults and longitudinal analysis showed that the general pattern of maturation consisted in an increase in long-distance connections with posterior cortical regions and a decrease in short connections within prefrontal cortical areas. Latent growth curve analysis showed that EC scores were predicted by a linear increase over time in DMN integrity in alpha band and an increase in the segregation between DMN and TPN in beta band. These data confirm the neural basis of observed in fMRI research maturation-related changes and show that integrity of the DMN and sufficient level of segregation between DMN and TPN is a prerequisite for appropriate attentional and behavioral control.
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Imaging studies have described hemodynamic activity during fear conditioning protocols with stimulus trains in which a visual conditioned stimulus (CS+) is paired with an aversive unconditioned stimulus (US, painful laser pulse) while another visual stimulus is unpaired (CS-). We now test the hypothesis that CS Event Related Spectral Perturbations (ERSPs) are related to ratings of CS Expectancy (likelihood of pairing with the US), Valence (unpleasantness) and Salience (ability to capture attention). ERSP windows in EEG were defined by both time after the CS and frequency, and showed increased oscillatory power (Event Related Synchronization, ERS) in the Delta/Theta Windows (0-8Hz) and the Gamma Window (30-55Hz). ⋯ The CS Valence and Salience were greater for CS+ than CS-, and were correlated with each other and with the ERD at overlapping channels, particularly in the Alpha Window. Expectancy and CS Skin Conductance Response were greater for CS+ than CS- and were correlated with ERSP at fewer channels than Valence or Salience. These results suggest that Alpha ERSP activity during fear conditioning reflects Valence and Salience of the CSs more than conditioning per se.
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Previous work (Brown et al., 2003a,b) has shown that limb position drifts when individuals make repetitive movements in the absence of visual feedback. The purpose of this study was to examine whether limb position drift might reflect a misalignment in visual and proprioceptive maps by examining the nature of information used to specify new movements from a drifted limb position. In a virtual reality (VR) environment, participants made continuous movements with their dominant right hand between two targets positioned 15cm apart, paced by a 0.625-Hz metronome. ⋯ For new movement specification, accurate proprioceptive information about the drifted limb position was used, even though it was apparently not available for detecting drift in the first place. Movement distance varied directly with the extent of limb drift, although the differentiation of visual and proprioceptive control of distance could not be analyzed, as our control conditions were not significantly different for this measure. We suggest that movement drift, in the absence of visual feedback during cyclic repetitive movements, reflects a misalignment between largely accurate visual and proprioceptive maps, rather than a weighted fusion of the two modalities.