Previous studies have demonstrated that stable and adaptive attention processes are mediated by partly overlapping, but distinct, brain areas. Dorsal medial PFC and anterior insula may form a "core network" for attention control, which is believed to operate on both temporal scales. However, both the existence of such a network as well as the unique functional topography for adaptive and stable attention processes is still highly debated. In this study, 87 healthy participants performed a clinical not-X continuous performance test optimized for use in a mixed block and event-related fMRI design. We observed overlapping activations related to stable and adaptive attention processes in dorsal medial PFC and anterior insula/adjacent cortex as well as in the right inferior parietal lobe and middle temporal gyrus. We also identified areas of activations uniquely related to stable and adaptive attention processes in widespread cortical, cerebellar, and subcortical areas. Interestingly, the functional topography within the PFC indicated a rostro-caudal distribution of adaptive, relative to stable, attention processes. There was also evidence for a time-on-task effect for activations related to stable, but not adaptive, attention processes. Our results provide further evidence for a "core network" for attention control that is accompanied by unique areas of activation involved in domain-specific processes operating on different temporal scales. In addition, our results give new insights into the functional topography of stable and adaptive attention processes and their temporal dynamics in the context of an extensively used clinical attention test.

Purpose: To use dynamic contrast-enhanced (DCE) and diffusion-weighted (DW) MRI at 3 Tesla (T) for early evaluation of treatment effects in breast cancer patients undergoing neoadjuvant chemotherapy (NAC), and assess the reliability of DW-MRI.Materials and Methods: DW-and DCE-MRI acquisitions of 15 breast cancer patients were performed before and after one cycle of NAC. MRI tumor diameter and volume, apparent diffusion coefficient (ADC) and kinetic parameters (K trans , v e ) were derived. The reliability of ADC before NAC was assessed. Changes in MRI parameters after NAC were analyzed, and logistic regression analysis was used to find the best predictors for pathologic response. Results:The reliability for ADC values was high, with intraclass correlation coefficient of 0.84 (P ¼ 0.001). After one cycle of NAC, MRI tumor diameter (8%, P ¼ 0.005) and tumor volume (30%, P ¼ 0.008) was reduced for all patients, while ADC mean values increased (0.12 mm 2 /s, P ¼ 0.008). The best predictor for treatment response was a change in MRI tumor diameter with mean error rate of 0.167 (13% for responders, 5% for nonresponders, P ¼ 0.291).Conclusion: Changes in MRI derived tumor diameter and ADC after only one cycle of NAC could provide a valuable tool for early evaluation of treatment effects in breast cancer patients.

In the brain, intracellular iron is essential for cellular metabolism. However, an overload of free iron is toxic, inducing oxidative stress and cell death. Although an increase of striatal iron has been related to atrophy and impaired cognitive performance, the link between elevated iron and altered brain activity in aging remains unexplored. In a sample of 37 younger and older adults, we examined whether higher striatal iron concentration could underlie age-related differences in frontostriatal activity induced by mental imagery of motor and non-motor scenes, and poorer recall of the scenes. Higher striatal iron concentration was linked to underrecruitment of frontostriatal regions regardless of age and striatal volume, the iron-activity association in right putamen being primarily driven by the older adults. In older age, higher striatal iron was related to poorer memory. Altered astrocytic functions could account for the link between brain iron and brain activity, as astrocytes are involved in iron buffering, neurovascular coupling, and synaptic activity. Our preliminary findings, which need to be replicated in a larger sample, suggest a potential frontostriatal target for intervention to counteract negative effects of iron accumulation on brain function and cognition.

Decision-making ability, psychopathology, and brain connectivityHighlights d Young people have a general decision-making ability, which we call ''decision acuity'' d Decision acuity is reflected in how strongly connected certain brain networks are d Low decision acuity is associated with general social function psychopathology

Resting-state spontaneous fluctuations have revealed individual differences in the functional architecture of brain networks. Previous research indicates that the striatal network shows alterations in neurological conditions but also in normal aging. However, the neurobiological mechanisms underlying individual differences in striatal resting-state networks (RSNs) have been less explored. One candidate that may account for individual differences in striatal spontaneous activity is the level of local iron accumulation. Excessive iron in the striatum has been linked to a loss of structural integrity and reduced brain activity during task performance in aging. Using independent component analysis in a sample of 42 younger and older adults, we examined whether higher striatal iron content, quantified using relaxometry, underlies individual differences in spontaneous fluctuations of RSNs in general, and of the striatum in particular. Higher striatal iron content was linked to lower spontaneous coherence within both caudate and putamen RSNs regardless of age. No such links were observed for other RSNs. Moreover, the number of connections between the putamen and other RSNs was negatively associated with iron content, suggesting that iron modulated the degree of cross-talk between the striatum and cerebral cortex. Importantly, these associations were primarily driven by the older group. Finally, a positive association was found between coherence in the putamen and motor performance, suggesting that this spontaneous activity is behaviorally meaningful. A follow-up mediation analysis also indicated that functional connectivity may mediate the link between striatal iron and motor performance. Our preliminary findings suggest that striatal iron potentially accounts for individual differences in spontaneous striatal fluctuations, and might be used as a locus of intervention.

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