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In this study we used functional magnetic resonance imaging to investigate age-related changes in large-scale brain functional networks during memory encoding and recognition in 12 younger and 16 older adults. For each participant, functional brain networks were constructed by computing temporal correlation matrices of 90 brain regions and analyzed using graph theoretical approaches. We found the age-related changes mainly in the long-range connections with widespread reductions associated with aging in the fronto-temporal and temporo-parietal regions, and a few age-related increases in the posterior parietal regions. Graph theoretical analysis revealed that the older adults had longer path lengths linking different regions in the functional brain networks as compared to the younger adults. Further analysis indicated that the increases in shortest path length in the networks were combined with the loss of long-range connections. Finally, we showed that for older adults, frontal areas played reduced roles in the network (reduced regional centrality), whereas several default-mode regions played increased roles relative to younger subjects (increased regional centrality). Together, our results suggest that normal aging is associated with disruption of large-scale brain systems during the performance of memory tasks, which provides novel insights into the understanding of age-related decline in multiple cognitive functions.

International audience; Ausgangspunkt der folgenden Überlegungen ist ein Referat CHRISTOPHE DUMAS', gehalten im Rahmen einer Tagung zum Thema des Nationalsozialismus im zeitgenössischen deutschen Film 1 , das sich mit Philipp Stölzls ‹Nordwand› 2 aus dem Jahr 2008 auseinandersetzte. DUMAS weist auf die Spezifität des deutschen Bergfilms hin, der in den 20er und 30er Jahren des 20. Jahrhunderts seine Blütezeit erlebte und seit je im Geruch stand, besondere Affinitäten zum Nationalsozialismus zu haben. Zu Recht unterstreicht er die Absicht Stölzls, dem Bergfilm sein ideologisches Substrat zu entziehen und ihm damit neue Entwicklungschancen zu eröffnen. Insofern geht es, wie DUMAS zutreffend formuliert, darum, den Bergfilm zu «desemantisieren» bzw. zu «resemantisieren», d.h. ihn von der nationalsozialistischen Ideologie, die ihn mehr oder weniger deutlich durchtränkte, zu befreien, wobei das alte Modell der 20er und 30er Jahre durch intertextuelle Verweise heraufbeschworen und zugleich unterminiert wird. Dies ist tatsächlich ein zentraler Aspekt von Stölzls Film, der in der Folge weiter ausgearbeitet werden soll, wobei als roter Faden die Dichotomie von Zentrum und Peripherie dienen wird. Thema von ‹Nordwand› ist, aus diesem Blickwinkel gesehen, die Einflussnahme der deutschen Reichshauptstadt Berlin und der dort ansässigen Regierung auf Geschehnisse an der Peripherie, im Gebirge, und auf Menschen, die im Gebirge zu Hause sind. Über verschiedene Medien wird in ‹Nordwand› nationalsozialistische Propaganda vom Zentrum an die Peripherie getragen. Zwar wird der Bergfilm selbst nicht direkt ins Bild gebracht, doch werden in einer der Eingangsszenen Zuschauer in einer Wochenschau gezeigt, darunter eine junge Frau, Luise Fellner, von der noch die Rede sein wird. In «martialischem Ton» 3 , wird eine Szene kommentiert, in der ein Flugzeug in nächster Nähe der Eiger-Nordwand erscheint. Es handle sich um die deutsche Fliegerlegende Ernst Udet, die furchtlos-wie könnte es anders sein-die deutschen Bergsteiger Karl Mehringer und Max Sedlmayr sucht, welche beim Versuch der Erstbesteigung umgekommen sind und deren Leichen noch nicht geborgen 1 Christophe Dumas: ‹Nordwand› (2008)-nouvelle vision d'un genre ancien ?, in: Le national-socialisme dans le cinéma allemand contemporain, hg. v. HELENE CAMARADE

Selective attention has traditionally been viewed as a sensory processing modulator that promotes cognitive processing efficiency by favoring relevant stimuli while inhibiting irrelevant stimuli. However, the cross-modal processing of irrelevant information during working memory (WM) has been rarely investigated. In this study, the modulation of irrelevant auditory information by the brain during a visual WM task was investigated. The N100 auditory evoked potential (N100-AEP) following an auditory click was used to evaluate the selective attention to auditory stimulus during WM processing and at rest. N100-AEP amplitudes were found to be significantly affected in the left-prefrontal, mid-prefrontal, right-prefrontal, left-frontal, and mid-frontal regions while performing a high WM load task. In contrast, no significant differences were found between N100-AEP amplitudes in WM states and rest states under a low WM load task in all recorded brain regions. Furthermore, no differences were found between the time latencies of N100-AEP troughs in WM states and rest states while performing either the high or low WM load task. These findings suggested that the prefrontal cortex (PFC) may integrate information from different sensory channels to protect perceptual integrity during cognitive processing.

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Very low‐frequency blood oxygen level‐dependent (BOLD) fluctuations have emerged as a valuable tool for describing brain anatomy, neuropathology, and development. Such fluctuations exhibit power law frequency dynamics, with largest amplitude at lowest frequencies. The biophysical mechanisms generating such fluctuations are poorly understood. Using publicly available data from 1,019 subjects of age 7–30, we show that BOLD fluctuations exhibit temporal complexity that is linearly related to local connectivity (regional homogeneity), consistently and significantly covarying across subjects and across gray matter regions. This relationship persisted independently of covariance with gray matter density or standard deviation of BOLD signal. During late neurodevelopment, BOLD fluctuations were unchanged with age in association cortex while becoming more random throughout the rest of the brain. These data suggest that local interconnectivity may play a key role in establishing the complexity of low‐frequency BOLD fluctuations underlying functional magnetic resonance imaging connectivity. Stable low‐frequency power dynamics may emerge through segmentation and integration of connectivity during development of distributed large‐scale brain networks. Hum Brain Mapp 35:1273–1283, 2014. © 2013 Wiley Periodicals, Inc.

AbstractBOLD fMRI is widely applied in human neuroscience but is limited in its spatial specificity due to a cortical‐depth‐dependent venous bias. This reduces its localization specificity with respect to neuronal responses, a disadvantage for neuroscientific research. Here, we modified a submillimeter BOLD protocol to selectively reduce venous and tissue signal and increase cerebral blood volume weighting through a pulsed saturation scheme (dubbed Arterial Blood Contrast) at 7 T. Adding Arterial Blood Contrast on top of the existing BOLD contrast modulated the intracortical contrast. Isolating the Arterial Blood Contrast showed a response free of pial‐surface bias. The results suggest that Arterial Blood Contrast can modulate the typical fMRI spatial specificity, with important applications in in‐vivo neuroscience.

Bright-light interventions have successfully been used to reduce depression symptoms in patients with seasonal affective disorder, a depressive disorder most frequently occurring during seasons with reduced daylight availability. Yet, little is known about how light exposure impacts human brain function, for instance on risk taking, a process affected in depressive disorders. Here we examined the modulatory effects of bright-light exposure on brain activity during a risk-taking task. Thirty-two healthy male volunteers living in the greater Copenhagen area received 3weeks of bright-light intervention during the winter season. Adopting a double-blinded dose-response design, bright-light was applied for 30minutes continuously every morning. The individual dose varied between 100 and 11.000lx. Whole-brain functional MRI was performed before and after bright-light intervention to probe how the intervention modifies risk-taking related neural activity during a two-choice gambling task. We also assessed whether inter-individual differences in the serotonin transporter-linked polymorphic region (5-HTTLPR) genotype influenced the effects of bright-light intervention on risk processing. Bright-light intervention led to a dose-dependent increase in risk-taking in the LA/LA group relative to the non-LA/LA group. Further, bright-light intervention enhanced risk-related activity in ventral striatum and head of caudate nucleus in proportion with the individual bright-light dose. The augmentation effect of light exposure on striatal risk processing was not influenced by the 5-HTTLPR-genotype. This study provides novel evidence that in healthy non-depressive individuals bright-light intervention increases striatal processing to risk in a dose-dependent fashion. The findings provide converging evidence that risk processing is sensitive to bright-light exposure during winter.

Abstract Background Fine motor and coordination problems are frequently reported among adolescents born preterm. We aimed to assess performance in hand coordination tasks and to compare concurrent brain activation between adolescents born very preterm and at term at 13 years. Methods A total of 34 right-handed adolescents born very preterm (gestational age less than 32 weeks/birth weight ≤1500 grams) and 37 controls born at term during 2003 to 2006 in Turku University Hospital, Finland, were recruited. At 13 years, finger opposition and diadochokinesis were assessed, and brain functional magnetic resonance imaging data were acquired while the adolescents performed unimanual hand coordination tasks in response to visual cue. Results Adolescents born very preterm performed similar to controls in hand coordination tasks. The very preterm group evoked greater brain activation than the controls in the right precentral gyrus and in the right postcentral gyrus during left-hand finger opposition and in the right postcentral gyrus during left-hand diadochokinesis. Within the very preterm group, lower gestational age was associated with reduced activation in the left superior parietal lobule during right-hand diadochokinesis. Regarding left-hand tasks, lower gestational age was associated with stronger activation in the right cerebellar lobule V and left cerebellar lobule VI during finger opposition and stronger activation in the right superior parietal lobule during diadochokinesis. Conclusions Very preterm birth affected hand coordination-related brain activation. Most of the effects were found for nondominant hand. Clinical performance during the hand coordination tasks was similar in adolescents born very preterm and controls.