Neuropsychologia
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A number of behavioral changes occur between late childhood and adulthood, including maturation of social cognition, reward receptivity, impulsiveness, risk-taking and cognitive control. Although some of these abilities show linear improvements with age, some abilities may temporarily worsen, reflecting both the restructuring and/or strengthening of connections within some brain systems. The current study uses resting state functional connectivity to examine developmental differences between late childhood and adulthood in task positive (TP) regions, which play a role in cognitive control functions, and task negative (TN) regions, which play a role in social cognition, self-referential, and internally-directed thought. ⋯ Stronger anticorrelations were found in the TN maps of the adult group for the right anterior insula/inferior frontal gyrus, bilateral anterior inferior parietal lobule, bilateral superior parietal lobule and an anterior portion of the right posterior cingulate cortex. There was a significant brain-behavior relationship between the strength of anticorrelation in these regions and inhibitory control performance on two Go/No-go tasks suggesting that the development of anticorrelations between late childhood and adulthood supports mature inhibitory control. Overall, maturation of these networks occurred in specific regions which are associated with cognitive control of goal-directed behavior, including those involved in working memory, social cognition, and inhibitory control.
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Working memory (WM) processes help keep information in an active state so it can be used to guide future behavior. Although numerous studies have investigated brain activity associated with spatial WM in humans and monkeys, little research has focused on the neural mechanisms of WM for temporal order information, and how processing of temporal and spatial information might differ. Available evidence indicates that similar frontoparietal regions are recruited during temporal and spatial WM, although there are data suggesting that they are distinct processes. ⋯ The present results are consistent with the idea that neural oscillatory patterns provide distinct mechanisms for the maintenance of temporal and spatial information in WM. Specifically, theta oscillations are most critical for the maintenance of temporal information in WM. Possible roles of higher frequency oscillations in temporal and spatial memory are also discussed.
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Behavioral evidence indicates that odor evoked autobiographical memories (OEAMs) are older, more emotional, less thought of and induce stronger time traveling characteristics than autobiographical memories (AMs) evoked by other modalities. The main aim of this study was to explore the neural correlates of AMs evoked by odors as a function of retrieval cue. Participants were screened for specific OEAMs and later presented with the odor cue and its verbal referent in an fMRI paradigm. ⋯ Furthermore, odor cues activated areas related to emotional processing, such as limbic and tempopolar regions significantly more. In contrast, word cues relative to odor cues recruited a more widespread and bilateral prefrontal activity. Hippocampus activity did not vary as function of the remoteness of the memory, but recollection of OEAMs from the 1(st) vs the 2(nd) decade of life showed specific activation in the right OFC, whereas the 2(nd) reflected a higher activation in the left inferior frontal gyrus.
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We tested human participants on a modified peak procedure in order to investigate the relation between interval timing and reward processing, and examine the interaction of this relation with three different dopamine-related gene polymorphisms. These gene polymorphisms affected the expression of catechol-o-methyltransferase, which catabolizes synaptic dopamine primarily in the prefrontal cortex (COMT Val158Met polymorphism), D2 dopamine receptors primarily in the striatum (DRD2/ANKK1-Taq1a polymorphism), and dopamine transporters, which clear synaptic dopamine in the striatum (DAT 3' VNTR variant). The inclusion of these polymorphisms allowed us to investigate dissociable aspects of the dopamine system and their interaction with reward magnitude manipulations in shaping timed behavior. ⋯ Furthermore, the COMT polymorphism that leads to higher prefrontal dopamine resulted in weaker manifestation of memory variability (relative to threshold variability) in timed behavior. There was no effect of DAT polymorphisms on any of the core behavioral measures. These results suggest that the reward modulates decision thresholds rather than clock speed, and that these effects are specific to COMT and DRD2 epistasis effects that presumably constitute a balanced prefrontal and striatal dopamine transmission.