The effects of flavanone-rich citrus juice on cognitive function and cerebral blood flow: an acute, randomised, placebo-controlled cross-over trial in healthy, young adults.

A plausible mechanism underlying flavonoid-associated cognitive effects is increased cerebral blood flow (CBF). However, behavioural and CBF effects following flavanone-rich juice consumption have not been explored. The aim of this study was to investigate whether consumption of flavanone-rich juice is associated with acute cognitive benefits and increased regional CBF in healthy, young adults. An acute, single-blind, randomised, cross-over design was applied with two 500-ml drink conditions - high-flavanone (HF; 70·5 mg) drink and an energy-, and vitamin C- matched, zero-flavanone control. A total of twenty-four healthy young adults aged 18-30 years underwent cognitive testing at baseline and 2-h after drink consumption. A further sixteen, healthy, young adults were recruited for functional MRI assessment, whereby CBF was measured with arterial spin labelling during conscious resting state at baseline as well as 2 and 5 h after drink consumption. The HF drink was associated with significantly increased regional perfusion in the inferior and middle right frontal gyrus at 2 h relative to baseline and the control drink. In addition, the HF drink was associated with significantly improved performance on the Digit Symbol Substitution Test at 2 h relative to baseline and the control drink, but no effects were observed on any other behavioural cognitive tests. These results demonstrate that consumption of flavanone-rich citrus juice in quantities commonly consumed can acutely enhance blood flow to the brain in healthy, young adults. However, further studies are required to establish a direct causal link between increased CBF and enhanced behavioural outcomes following citrus juice ingestion.

Variation in styles of rifting in the Gulf of California.

Constraints on the structure of rifted continental margins and the magmatism resulting from such rifting can help refine our understanding of the strength of the lithosphere, the state of the underlying mantle and the transition from rifting to seafloor spreading. An important structural classification of rifts is by width, with narrow rifts thought to form as necking instabilities (where extension rates outpace thermal diffusion) and wide rifts thought to require a mechanism to inhibit localization, such as lower-crustal flow in high heat-flow settings. Observations of the magmatism that results from rifting range from volcanic margins with two to three times the magmatism predicted from melting models to non-volcanic margins with almost no rift or post-rift magmatism. Such variations in magmatic activity are commonly attributed to variations in mantle temperature. Here we describe results from the PESCADOR seismic experiment in the southern Gulf of California and present crustal-scale images across three rift segments. Over short lateral distances, we observe large differences in rifting style and magmatism--from wide rifting with minor synchronous magmatism to narrow rifting in magmatically robust segments. But many of the factors believed to control structural evolution and magmatism during rifting (extension rate, mantle potential temperature and heat flow) tend to vary over larger length scales. We conclude instead that mantle depletion, rather than low mantle temperature, accounts for the observed wide, magma-poor margins, and that mantle fertility and possibly sedimentary insulation, rather than high mantle temperature, account for the observed robust rift and post-rift magmatism.

Autonomic adaptations mediate the effect of hydration on brain functioning and mood: Evidence from two randomized controlled trials.

Dehydration (water loss >2.0% of body weight) has significant negative effects on physical and mental performance. In two studies the effects of minor hypo-hydration (water loss <1.0% of body weight) on CNS function, mood and cardiovascular functioning were measured. Study 1: On two mornings twelve male participants were exposed to a temperature of 30 °C for four hours and either did or did not drink two 150 ml glasses of water during that time. Study 2: Fifty-six (25 M) individuals were exposed to the same 30 °C environment and randomly allocated to either drink (2 × 150 ml) or not drink. When not given water 0.59% (Study 1) and 0.55% (Study 2) bodyweight was lost. Participant's heart rate variability (HRV) was measured, and they rated their thirst and mood. In study 1, participants participated in an fMRI protocol during which they completed a modified version of the Paced Auditory Serial Addition Test (PASAT), at the end of which they rated its difficulty. Decreases in fMRI BOLD activity in the orbito-frontal cortex, ventral cingulate gyrus, dorsal cingulate cortex, hypothalamus, amygdala, right striatum, post-central gyrus and superior parietal cortex were observed when participants were hypo-hydrated. These deactivations were associated with reduced HRV, greater perceived effort, and more anxiety. In study 2 declines in HRV were found to mediate the effect of hypo-hydration on ratings of anxiety. These data are discussed in relation to a model that describes how autonomic regulatory and interoceptive processes may contribute to the affective consequences of minor hypo-hydration.

Mild exercise in female subjects impairs complex learning independent of hydration status and emotion.

INTRODUCTION: Depending on type, intensity and duration, exercise can have both beneficial and detrimental effects on cognitive function. The impact of exercise on learning and memory is also sensitive to hydration status, so we hypothesized that mild hypohydration induced with exercise, will adversely impact executive and complex memory function tasks and that these changes in cognitive function are independent of changes in emotion. METHODS: Using a cross over design, on separate days 11 women exercised on a recumbent bicycle. On day 1, women exercised to 1.5% hypohydration at 34°C, and <10% rh, on day 2, water loss from sweating was replaced by drinking water (euhydration). Pre- and post-euhydration and hypohydration, subjects underwent computer based cognitive tasks (simple, learning, memory, executive function) and visual analog testing to determine emotion. RESULTS: Exercise increased Groton Maze Learning Test errors within both conditions: [Pre: 41.5±11.8, Post: 46.8±12.4, and Pre: 41.9±9.2, Post: 46.5±12.9, hypohydrated and euhydrated, respectively, Pre vs Post, ANOVA, time effect, P=0.007], a test of acquisition, storage, and use of new knowledge. None of the measures of emotion were affected by exercise under either hydration condition. CONCLUSIONS: A bout of mild aerobic exercise compromised performance on a complex learning and memory task, but this change was unaffected by hydration status or emotion.

Near-field deformation from the El Mayor-Cucapah earthquake revealed by differential LIDAR.

Large [moment magnitude (M(w)) ≥ 7] continental earthquakes often generate complex, multifault ruptures linked by enigmatic zones of distributed deformation. Here, we report the collection and results of a high-resolution (≥nine returns per square meter) airborne light detection and ranging (LIDAR) topographic survey of the 2010 M(w) 7.2 El Mayor-Cucapah earthquake that produced a 120-kilometer-long multifault rupture through northernmost Baja California, Mexico. This differential LIDAR survey completely captures an earthquake surface rupture in a sparsely vegetated region with pre-earthquake lower-resolution (5-meter-pixel) LIDAR data. The postevent survey reveals numerous surface ruptures, including previously undocumented blind faults within thick sediments of the Colorado River delta. Differential elevation changes show distributed, kilometer-scale bending strains as large as ~10(3) microstrains in response to slip along discontinuous faults cutting crystalline bedrock of the Sierra Cucapah.

The function of ascorbate oxidase in tobacco.

The function of the apoplastic enzyme ascorbate oxidase (AO) was investigated in tobacco (Nicotiana tabacum). The abundance of AO mRNA was up-regulated by light. Cytosolic ascorbate peroxidase (APX1) transcripts were also highest in the light. In contrast, L-galactono-gamma-lactone dehydrogenase, stromal APX, and thylakoid APX transcripts remained constant over the day/night cycle. Salicylic acid inhibited growth, increased expression of the pathogenesis-related protein (PR) 1a, and decreased AO transcript abundance. In contrast, the application of auxin enhanced growth and increased AO and PR 1a gene expression. Therefore, AO transcript abundance varied in a manner similar to hormone-mediated changes in plant growth. To study the effects of modified AO expression on growth, transformed tobacco plants expressing AO in the sense and antisense orientations were generated. The resultant large changes in apoplastic AO activity in the transformed tobacco plants had little effect on whole leaf ascorbate (AA) content, but they had dramatic effects on apoplastic AA levels. Enhanced AO activity oxidized the apoplastic AA pool, whereas decreased AO activity increased the amount of AA compared with dehydroascorbate. A relationship was observed between AO activity and plant height and biomass. Native AO transcript levels were no longer subject to light/dark regulation in AO sense and antisense plants. Taken together, these data show that there is an interaction between hormone, redox, and light signals at the level of the apoplast via modulation of ion of AA content.