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Background: Anhedonia stands as a life-threatening transdiagnostic feature of many mental illnesses, most notably major depression and involves neural circuits for processing reward information. The paraventricular nucleus of the thalamus (PVT) is associated with reward-seeking behavior, however, links between the PVT circuit and anhedonia have not been investigated in humans., Methods: In a sample of adults with and without psychiatric symptoms (n = 75, 18-41 years, 55 female), we generated an anhedonia factor score for each participant using a latent factor analysis, utilizing data from depression and anxiety assessments. Functional connectivity between the PVT and the nucleus accumbens (NAc) was calculated from high-resolution (1.5 mm) resting state fMRI., Results: Anhedonia factor scores showed a positive relationship with functional connectivity between the PVT and the NAc, principally in males and in those with psychiatric symptoms. In males, connectivity between other midline thalamic nuclei and the NAc did not show these relationships, suggesting that this link may be specific to PVT., Limitations: This cohort was originally recruited to study depression and not anhedonia per se. The distribution of male and female participants in our cohort was not equal. Partial acquisition in high-resolution fMRI scans restricted regions of interest outside of the thalamus and reward networks., Conclusions: We report evidence that anhedonia is associated with enhanced functional connectivity between the PVT and the NAc, regions that are relevant to reward processing. These results offer clues as to the potential prevention and prevention and treatment of anhedonia., Competing Interests: Declaration of competing interest None of the authors have relevant conflicts of interest to report., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Sediment source fingerprinting using biomarker properties has led to new insights in our understanding of land use contributions to time-integrated suspended sediment samples at catchment scale. A time-integrated mass-flux sampler (TIMS; also known as the 'Phillips' sampler), a cost-effective approach for suspended sediment collection in situ. Such samplers are widely being used to collect sediment samples for source fingerprinting purposes, including studies using biomarkers as opposed to more conventional tracer properties. Here, we assessed the performance of TIMS for collecting representative sediment samples for biomarkers during high discharge events in a small lowland grassland-dominated catchment. Concentrations of long odd-chain n-alkanes (> C 23 ) and both saturated free and bound fatty acids (C 14 -C 32 ), as well as compound-specific 13 C were compared between sediment collected by both TIMS and autosamplers (ISCO). The results showed that concentrations of alkanes, free fatty acids, and bound fatty acids are consistently comparable between TIMS and ISCO suspended sediment samples. Similarly, compound-specific 13 C signals were not found to be significantly different in the suspended sediment samples collected using the different samplers. However, different magnitudes of resemblance in biomarker concentrations and compositions between the samples collected using the two sediment collection methods were confirmed by overlapping index and symmetric coordinates-based correlation analysis. Here, the difference is attributed to the contrasting temporal basis of TIMS (time-integrated) vs. ISCO (discrete) samples, as well as potential differences in the particle sizes collected by these different sediment sampling methods. Nevertheless, our findings suggest that TIMS can be used to generate representative biomarker data for suspended sediment samples collected during high discharge events., (© 2024. The Author(s).)

Background: Anhedonia may contribute to individual differences in delay discounting (DD). In prior work, we found that higher anhedonia was associated with shallower DD in healthy control (HC) participants but steeper DD in individuals with posttraumatic stress disorder (PTSD). In this study, we aimed to directly compare the relationship between anhedonia and DD across groups and to identify functional brain correlates of this interaction., Methods: Participants (HC group: n = 23, DSM-5 PTSD group: n = 23) completed a questionnaire assessing anhedonia (Snaith-Hamilton Pleasure Scale [SHAPS]), task-based functional magnetic resonance imaging of decision making including DD, and resting-state functional magnetic resonance imaging. Task-based activity and resting-state functional connectivity were evaluated in reward-related regions that have also been implicated in PTSD (nucleus accumbens [NAcc], right anterior insula)., Results: Higher SHAPS scores were associated with steeper DD in PTSD, but there was no relationship between DD and SHAPS in the HC group. There was a significant group-by-SHAPS interaction for NAcc activity, t 31  = 2.92, p = .007: Greater NAcc activity when immediate rewards were chosen was associated with higher SHAPS in the PTSD group but lower SHAPS in the HC group. In resting-state functional connectivity, there was a group-by-SHAPS interaction between the NAcc seed and right parietal and frontal pole clusters., Conclusions: These results extend prior findings that anhedonia is associated with steeper DD in PTSD and demonstrate that this behavioral finding occurs in the context of NAcc hyperactivity to immediate rewards and hyperconnectivity in anhedonic individuals with PTSD., (Copyright © 2023 Society of Biological Psychiatry. Published by Elsevier Inc. All rights reserved.)

Introduction: Pituitary adenylate cyclase-activating polypeptide (PACAP) regulates plasticity in brain systems underlying arousal and memory and is associated with posttraumatic stress disorder (PTSD). Research in animal models suggests that PACAP modulates entorhinal cortex (EC) input to the hippocampus, contributing to impaired contextual fear conditioning. In PTSD, PACAP is associated with higher activity of the amygdala to threat stimuli and lower functional connectivity of the amygdala and hippocampus. However, PACAP-affiliated structural alterations of these regions have not been investigated in PTSD. Here, we examined whether peripheral PACAP levels were associated with neuronal morphology of the amygdala and hippocampus (primary analyses), and EC (secondary) using Neurite Orientation Dispersion and Density Imaging. Methods: Sixty-four (44 female) adults (19 to 54 years old) with DSM-5 Criterion A trauma exposure completed the Clinician-Administered PTSD Scale (CAPS-5), a blood draw, and magnetic resonance imaging. PACAP38 radioimmunoassay was performed and T1-weighted and multi-shell diffusion-weighted images were acquired. Neurite Density Index (NDI) and Orientation Dispersion Index (ODI) were quantified in the amygdala, hippocampus, and EC. CAPS-5 total score and anxious arousal score were used to test for clinical associations with brain structure. Results: Higher PACAP levels were associated with greater EC NDI ( β  = 0.0099, q  = 0.032) and lower EC ODI ( β  = -0.0073, q  = 0.047), and not hippocampal or amygdala measures. Neither EC NDI nor ODI was associated with clinical measures. Conclusions: Circulating PACAP levels were associated with altered neuronal density of the EC but not the hippocampus or amygdala. These findings strengthen evidence that PACAP may impact arousal-associated memory circuits in PTSD.

Diffuse pollutant transfers from agricultural land often constitute the bulk of annual loads in catchments and storm events dominate these fluxes. There remains a lack of understanding of how pollutants move through catchments at different scales. This is critical if the mismatch between the scales used to implement on-farm management strategies, compared to those used for assessment of environmental quality, is to be addressed. The aim of this study was to understand how the mechanisms of pollutant export may change when assessed at different scales and the corresponding implications for on-farm management strategies. A study was conducted within a 41 km 2 catchment containing 3 nested sub-catchments, instrumented to monitor discharge and various water quality parameters. Storm data over a 24-month period were analysed and hysteresis (HI) and flushing (FI) indices calculated for two water quality variables that are typically of environmental significance; NO 3 -N and suspended sediment (SSC). For SSC, increasing spatial scale had little effect on the mechanistic interpretation of mobilisation and the associated on-farm management strategies. At the three smallest scales NO 3 -N was chemodynamic with the interpretation of dominant mechanisms changing seasonally. At these scales, the same on-farm management strategies would be recommended. However, at the largest scale, NO 3 -N appeared unaffected by season and chemostatic. This would lead to a potentially very different interpretation and subsequent on-farm measures. The results presented here underscore the benefits of nested monitoring for extracting mechanistic understanding of agricultural impacts on water quality. The application of HI and FI indicates that monitoring at smaller scales is crucial. At large scales, the complexity of the catchment hydrochemical response means that mechanisms become obscured. Smaller catchments more likely represent critical areas within larger catchments where mechanistic understanding can be extracted from water quality monitoring and used to underpin the selection of on-farm mitigation measures., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Collins, A.L. reports financial support was provided by Biotechnology and Biological Sciences Research Council., (Copyright © 2023 The Authors. Published by Elsevier Inc. All rights reserved.)

White matter hyperintensities are a marker of small vessel cerebrovascular disease that are strongly related to cognition in older adults. Similarly, medial temporal lobe atrophy is well-documented in aging and Alzheimer's disease and is associated with memory decline. Here, we assessed the relationship between lobar white matter hyperintensities, medial temporal lobe subregional volumes, and hippocampal memory in older adults. We collected MRI scans in a sample of 139 older adults without dementia (88 females, mean age (SD) = 76.95 (10.61)). Participants were administered the Rey Auditory Verbal Learning Test (RAVLT). Regression analyses tested for associations among medial temporal lobe subregional volumes, regional white matter hyperintensities and memory, while adjusting for age, sex, and education and correcting for multiple comparisons. Increased occipital white matter hyperintensities were related to worse RAVLT delayed recall performance, and to reduced CA1, dentate gyrus, perirhinal cortex (Brodmann area 36), and parahippocampal cortex volumes. These medial temporal lobe subregional volumes were related to delayed recall performance. The association of occipital white matter hyperintensities with delayed recall performance was fully mediated statistically only by perirhinal cortex volume. These results suggest that white matter hyperintensities may be associated with memory decline through their impact on medial temporal lobe atrophy. These findings provide new insights into the role of vascular pathologies in memory loss in older adults and suggest that future studies should further examine the neural mechanisms of these relationships in longitudinal samples., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022. Published by Elsevier Inc.)

The perforant path, the white matter bundle connecting the entorhinal cortex (ERC) with the hippocampal formation deteriorates with age-related cognitive decline. Previous investigations using diffusion-weighted MRI to quantify perforant path integrity in-vivo have been limited due to image resolution or have quantified the perforant path using methods susceptible to partial volume effects such as the tensor model and without consideration of its 3-dimensional morphology. In this investigation, we use quantitative-anisotropy informed tractography derived from ultra-high resolution diffusion imaging (ZOOMit) to investigate structural connectivity of the perforant path and other medial temporal lobe (MTL) pathways in older adults (63 to 98 years old, n = 51). We show that graph density within the MTL declines with age and is associated with lower delayed recall performance. We also show that older age and poorer delayed recall are associated with reduced streamlines connecting the ERC and dentate gyrus of the hippocampus (the putative perforant path). This work suggest that intra-MTL connectivity may new candidate biomarkers for age-related cognitive decline., (Copyright © 2022 Elsevier Inc. All rights reserved.)

A child's death is a profound loss for mothers and affects hundreds of thousands of women. Mothers report inconsolable and progressive grief that is distinct from depression and impacts daily emotions and functions. The brain mechanisms responsible for this relatively common and profound mental health problem are unclear, hampering its clinical recognition and care. In an initial exploration of this condition, we used resting state functional MRI (fMRI) scans to examine functional connectivity in key circuits, and task-based fMRI to examine brain network activity in grieving mothers in response to pictures of their deceased child and as well as recognizable deceased celebrities and unfamiliar individuals. We compared nine mothers who had lost an adult child and aged-matched control mothers with a living child of a similar age. Additionally, we collected diffusion imaging scans to probe structural connectivity and complemented the imaging studies with neuropsychological assessments. Increased functional activation in Ventral Attention/Salience Networks accompanied by a reduced activation in the medial prefrontal cortex in response to the deceased child's picture robustly distinguished the grieving mothers from controls. Heightened resting-state functional connectivity between the paraventricular thalamic nucleus (PVT) and the amygdala distinguished the grieving mothers from the controls and correlated with subjective grief severity. Structurally, maternal grief and its severity were associated with alterations in corticolimbic white matter tracts. Finally, grieving mothers performed worse than controls on neuropsychological tests of learning, memory, and executive function, linked with grief severity. Reduced activation in cortical regions inhibiting emotions and changes in the PVT circuitry-a region involved in long-term emotional memories and decision making under conflict-distinguish grieving mothers from controls. Notably, the magnitude of neurobiological changes correlates with the subjective severity of grief. Together, these new discoveries delineate a prevalent and under-recognized mental health syndrome and chart a path for its appreciation and care., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Kark, Adams, Sathishkumar, Granger, McMillan, Baram and Yassa.)

Medial temporal lobe (MTL) atrophy is a core feature of age-related cognitive decline and Alzheimer's disease (AD). While regional volumes and thickness are often used as a proxy for neurodegeneration, they lack the sensitivity to serve as an accurate diagnostic test and indicate advanced neurodegeneration. Here, we used a submillimeter resolution diffusion weighted MRI sequence (ZOOMit) to quantify microstructural properties of hippocampal subfields in older adults (63-98 years old) using tensor derived measures: fractional anisotropy (FA) and mean diffusivity (MD). We demonstrate that the high-resolution sequence, and not a standard resolution sequence, identifies dissociable profiles for CA1, dentate gyrus (DG), and the collateral sulcus. Using ZOOMit, we show that advanced age is associated with increased MD of the CA1 and DG as well as decreased FA of the DG. Increased MD of the DG, reflecting decreased cellular density, mediated the relationship between age and word list recall. Further, increased MD in the DG, but not DG volume, was linked to worse spatial pattern separation. Our results demonstrate that ultrahigh-resolution diffusion imaging enables the detection of microstructural differences in hippocampal subfield integrity and will lead to novel insights into the mechanisms of age-related memory loss., (© 2022 Wiley Periodicals LLC.)

Agriculture is challenged to produce healthy food and to contribute to cleaner energy whilst mitigating climate change and protecting ecosystems. To achieve this, policy-driven scenarios need to be evaluated with available data and models to explore trade-offs with robust accounting for the uncertainty in predictions. We developed a novel model ensemble using four complementary state-of-the-art agroecosystems models to explore the impacts of land management change. The ensemble was used to simulate key agricultural and environmental outputs under various scenarios for the upper River Taw observatory, UK. Scenarios assumed (i) reducing livestock production whilst simultaneously increasing the area of arable where it is feasible to cultivate (PG2A), (ii) reducing livestock production whilst simultaneously increasing bioenergy production in areas of the catchment that are amenable to growing bioenergy crops (PG2BE) and (iii) increasing both arable and bioenergy production (PG2A + BE). Our ensemble approach combined model uncertainty using the tower property of expectation and the law of total variance. Results show considerable uncertainty for predicted nutrient losses with different models partitioning the uncertainty into different pathways. Bioenergy crops were predicted to produce greatest yields from Miscanthus in lowland and from SRC-willow (cv. Endurance) in uplands. Each choice of management is associated with trade-offs; e.g. PG2A results in a significant increase of edible calories (6736 Mcal ha -1 ) but reduced soil C (-4.32 t C ha -1 ). Model ensembles in the agroecosystem context are difficult to implement due to challenges of model availability and input and output alignment. Despite these challenges, we show that ensemble modelling is a powerful approach for applications such as ours, offering benefits such as capturing structural as well as data uncertainty and allowing greater combinations of variables to be explored. Furthermore, the ensemble provides a robust means for combining uncertainty at different scales and enables us to identify weaknesses in system understanding., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 The Authors. Published by Elsevier B.V. All rights reserved.)

Excessive sediment loss degrades freshwater quality and is prone to further elevation and variable source contributions due to the combined effect of extreme rainfall and differing land uses. To quantify erosion and sediment source responses across scales, this study integrated work at both field and catchment scale for two hydrologically contrasting winters (2018-19 and 2019-20). Sediment load was estimated at the field scale (grassland-arable conversion system). Sediment source apportionment work was undertaken at the catchment scale (4.5 km 2 ) and used alkanes, and both free and bound fatty acid carbon isotope signatures as diagnostic fingerprints to distinguish sediment sources: arable, pasture, woodland and stream banks. Sediment source apportionment based on bound fatty acids revealed a substantial shift in contributions, from stream banks dominating (70 ± 5%) in winter 2018-19, to arable land dominating (52 ± 7%) in the extreme wet winter 2019-20. Increases in sediment contributions from arable (∼3.9 times) and pasture (∼2.4 times) land at the catchment outlet during the winter 2019-20 were consistent with elevated sediment losses monitored at the field scale which indicated that low-magnitude high frequency rainfall alone increased sediment loss even from pasture by 350%. In contrast, carbon isotope signatures of alkanes and free fatty acids consistently estimated stream banks as a dominant source (i.e., ∼36% and ∼70% respectively) for both winters regardless of prolonged rainfall in winter 2019-20. Beyond quantifying the shifts in field scale sediment load and catchment scale sediment sources due to the changes in rainfall patterns, our results demonstrate valuable insight into how the fate of biotracers in soil and sediment manifests in the δ 13 C values of homologues and, in turn, their role in information gain for estimating sediment source contributions. Discrepancies in the estimated sediment source contributions using different biotracers indicate that without a careful appreciation of their biogeochemical limitations, erroneous interpretation of sediment source contributions can undermine management strategies for delivering more sustainable and resilient agriculture., (Copyright © 2022. Published by Elsevier Ltd.)

Background: Major Depressive Disorder, characterized by cognitive affective biases, is a considerable public health challenge. Past work has shown that higher depressive symptoms are associated with augmented memory of negative stimuli. In contrast, anxiety symptoms have been associated with overgeneralization of emotional memories. Given the high comorbidity of depression and anxiety, it is critical to understand how cognitive affective biases are differentially associated with clinical symptoms., Method: We used continuous measures of depression (Beck Depression Inventory [BDI-II]) and anxiety (Beck Anxiety Inventory [BAI]) to evaluate an adult sample (N = 79; 18-41 years old, 58 female). Emotional memory discrimination and recognition memory were tested using an emotional discrimination task. We applied exploratory factor analysis to questions from the BAI and BDI-II to uncover latent constructs consisting of negative affect, anhedonia, somatic anxiety, and cognitive anxiety., Results: We report evidence that anxious symptoms were associated with impaired recognition of negative items after accounting for age and sex. Our exploratory factor analysis revealed that impaired negative item recognition is largely associated with somatic and cognitive anxiety factors., Limitations: Interpretations in a mixed pathology sample, especially given collinearity among factors, may be difficult., Conclusions: We provide evidence that somatic and cognitive anxiety are related to impaired recognition memory for negative stimuli. Future clinical investigations should uncover the neurobiological basis supporting the link between recognition of negative stimuli and somatic/cognitive symptoms of anxiety., (Copyright © 2022. Published by Elsevier B.V.)

Periods of extreme wet-weather elevate agricultural diffuse water pollutant loads and climate projections for the UK suggest wetter winters. Within this context, we monitored nitrate and suspended sediment loss using a field and landscape scale platform in SW England during the recent extreme wet-weather of 2019-2020. We compared the recent extreme wet-weather period to both the climatic baseline (1981-2010) and projected near- (2041-2060) and far- (2071-2090) future climates, using the 95th percentiles of conventional rainfall indices generated for climate scenarios downscaled by the LARS-WG weather generator from the 19 global climate models in the CMIP5 ensemble for the RCP8.5 emission scenario. Finally, we explored relationships between pollutant loss and the rainfall indices. Grassland field-scale monthly average nitrate losses increased from 0.39-1.07 kg ha -1 (2016-2019) to 0.70-1.35 kg ha -1 (2019-2020), whereas losses from grassland ploughed up for cereals, increased from 0.63-0.83 kg ha -1 to 2.34-4.09 kg ha -1 . Nitrate losses at landscape scale increased during the 2019-2020 extreme wet-weather period to 2.04-4.54 kg ha -1 . Field-scale grassland monthly average sediment losses increased from 92-116 kg ha -1 (2016-2019) to 281-333 kg ha -1 (2019-2020), whereas corresponding losses from grassland converted to cereal production increased from 63-80 kg ha -1 to 2124-2146 kg ha -1 . Landscape scale monthly sediment losses increased from 8-37 kg ha -1 in 2018 to between 15 and 173 kg ha -1 during the 2019-2020 wet-weather period. 2019-2020 was most representative of the forecast 95th percentiles of >1 mm rainfall for near- and far-future climates and this rainfall index was related to monitored sediment, but not nitrate, loss. The elevated suspended sediment loads generated by the extreme wet-weather of 2019-2020 therefore potentially provide some insight into the responses to the projected >1 mm rainfall extremes under future climates at the study location., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2022 The Authors.)

Across species, unpredictable patterns of maternal behavior are emerging as novel predictors of aberrant cognitive and emotional outcomes later in life. In animal models, exposure to unpredictable patterns of maternal behavior alters brain circuit maturation and cognitive and emotional outcomes. However, whether exposure to such signals in humans alters the development of brain pathways is unknown. In mother-child dyads, we tested the hypothesis that exposure to more unpredictable maternal signals in infancy is associated with aberrant maturation of corticolimbic pathways. We focused on the uncinate fasciculus, the primary fiber bundle connecting the amygdala to the orbitofrontal cortex and a key component of the medial temporal lobe-prefrontal cortex circuit. Infant exposure to unpredictable maternal sensory signals was assessed at 6 and 12 months. Using high angular resolution diffusion imaging, we quantified the integrity of the uncinate fasciculus using generalized fractional anisotropy (GFA). Higher maternal unpredictability during infancy presaged greater uncinate fasciculus GFA in children 9-11 years of age ( n = 69, 29 female). In contrast to the uncinate, GFA of a second corticolimbic projection, the hippocampal cingulum, was not associated with maternal unpredictability. Addressing the overall functional significance of the uncinate and cingulum relationships, we found that the resulting imbalance of medial temporal lobe-prefrontal cortex connectivity partially mediated the association between unpredictable maternal sensory signals and impaired episodic memory function. These results suggest that unbalanced maturation of corticolimbic circuits is a mechanism by which early unpredictable sensory signals may impact cognition later in life. SIGNIFICANCE STATEMENT Our prior work across species demonstrated that unpredictable patterns of maternal care are associated with compromised memory function. However, the neurobiological mechanisms by which this occurs in humans remain unknown. Here, we identify an association of exposure to unpredictable patterns of maternal sensory signals with the integrity of corticolimbic circuits involved in emotion and cognition using state-of-the-art diffusion imaging techniques and analyses. We find that exposure to early unpredictability is associated with higher integrity of the uncinate fasciculus with no effect on a second corticolimbic pathway, the cingulum. The resulting imbalance of corticolimbic circuit development is a novel mediator of the association between unpredictable patterns of maternal care and poorer episodic memory., (Copyright © 2021 the authors.)

Water quality impairment by elevated sediment loss is a pervasive problem for global water resources. Sediment management targets identify exceedance or the sediment loss 'gap' requiring mitigation. In the UK, palaeo-limnological reconstruction of sediment loss during the 100-150 years pre-dating the post-World War II intensification of agriculture, has identified management targets (0.20-0.35 t ha -1 yr -1 ) representing 'modern background sediment delivery to rivers'. To assess exceedance on land for grazing ruminant farming, an integrated approach combined new mechanistic evidence from a heavily-instrumented experimental farm platform and a scaling out framework of modelled commercial grazing ruminant farms in similar environmental settings. Monitoring (2012-2016) on the instrumented farm platform returned sediment loss ranges of 0.11-0.14 t ha -1 yr -1 and 0.21-0.25 t ha -1 yr -1 on permanent pasture, compared with between 0.19-0.23 t ha -1 yr -1 and 0.43-0.50 t ha -1 yr -1 and 0.10-0.13 t ha -1 yr -1 and 0.25-0.30 t ha -1 yr -1 on pasture with scheduled plough and reseeds. Excess sediment loss existed on all three farm platform treatments but was more extensive on the two treatments with scheduled plough and reseeds. Excessive sediment loss from land used by grazing ruminant farming more strategically across England, was estimated to be up to >0.2 t ha -1 yr -1 . Modelled scenarios of alternative farming futures, based on either increased uptake of interventions typically recommended by visual farm audits, or interventions selected using new mechanistic understanding for sediment loss from the instrumented farm platform, returned minimum sediment loss reductions. On the farm platform these were 2.1 % (up to 0.007 t ha -1 yr -1 ) and 5.1 % (up to 0.018 t ha -1 yr-1). More strategically, these were up to 2.8 % (0.014 t ha -1 yr -1 ) and 4.1 % (0.023 t ha -1 yr -1 ). Conventional on-farm measures will therefore not fully mitigate the sediment loss gap, meaning that more severe land cover change is required., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2020 The Author(s).)

Alterations in white matter integrity have been demonstrated in a number of psychiatric disorders involving emotional disruptions. One such pathway - the uncinate fasciculus - connects the orbitofrontal cortex (OFC) to the medial temporal lobes (MTL) and has been associated with early life adversity, maltreatment, anxiety, and depression. While it is purported to play a role in episodic memory and discrimination, its exact function remains poorly understood. We have previously described the role of the amygdala and dentate (DG)/CA3 fields of the hippocampus in the mnemonic discrimination of emotional experiences (i.e. emotional pattern separation). However, how this computation may be modulated by connectivity with the orbitofrontal cortex remains unknown. Here we asked if the uncinate fasciculus plays a role in influencing MTL subregional activity during emotional pattern separation. By combining diffusion imaging with high-resolution fMRI, we found that reduced integrity of the UF is related to elevated BOLD fMRI activation of the DG/CA3 subregions of the hippocampus during emotional lure discrimination. We additionally report that higher levels of DG/CA3 activity are associated with poorer memory performance, suggesting that greater activation in this network (possibly driven by CA3 recurrent collaterals) is associated with memory errors. Based on this work we suggest that the UF is one pathway that may allow the OFC to exert control on this network and improve discrimination of emotional experiences, although further work is necessary to fully evaluate this possibility. This work provides novel insight into the role of prefrontal interactions with the MTL, particularly in the context of emotional memory., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Rationale: The isotopic composition of oxygen bound to phosphorus (δ 18 O P value) offers an opportunity to gain insight into P cycling mechanisms. However, there is little information for tropical forest soils, which presents a challenge for δ 18 O P measurements due to low available P concentrations. Here we report the use of a rapid ammonium fluoride extraction method (Bray-1) as an alternative to the widely used anion-exchange membrane (AEM) method for quantification of δ 18 O P values of available P in tropical forest soils., Methods: We compared P concentrations and δ 18 O P values of available and microbial P determined by AEM and Bray-1 extraction for a series of tropical forest soils from Panama spanning a steep P gradient. This involved an assessment of the influence of extraction conditions, including temperature, extraction time, fumigation time and solution-to-soil ratio, on P concentrations and isotope ratios., Results: Depending on the extraction conditions, Bray-1 P concentrations ranged from 0.2 to 66.3 mg P kg -1 across the soils. Extraction time and temperature had only minor effects on Bray-1 P, but concentrations increased markedly as the solution-to-soil ratio increased. In contrast, extraction conditions did not affect Bray-1 δ 18 O P values, indicating that Bray-1 provides a robust measure of the isotopic composition of available soil P. For a relatively high P soil, available and fumigation-released (microbial) δ 18 O P values determined by Bray-1 extraction (20‰ and 16‰, respectively) were higher than those determined by the AEM method (18‰ and 12‰, respectively), which we attribute to slightly different P pools extracted by the two methods and/or differences resulting from the longer extraction time needed for the AEM method., Conclusions: The short extraction time, insensitivity to extraction conditions and smaller mass of soil required to extract sufficient P for isotopic analysis make Bray-1extraction a suitable alternative to the AEM method for the determination of δ 18 O P values of available P in tropical soils., (© 2019 The Authors. Rapid Communications in Mass Spectrometry published by John Wiley & Sons Ltd.)

Field data about the effect of soil pH on phosphorus (P) cycling is limited. A promising tool to study P cycling under field conditions is the 18 O: 16 O ratio of phosphate (δ 18 O P ). In this study we investigate whether the δ 18 O P can be used to elucidate the effect of soil pH on P cycling in grasslands. Soils and plants were sampled from different fertilisation and lime treatments of the Park Grass long term experiment at Rothamsted Research, UK. The soils were sequentially extracted to isolate different soil P pools, including available P and corresponding δ 18 O P values were determined. We did not observe changes in plant δ 18 O P value, but soil P δ 18 O P values changed, and lower δ 18 O P values were associated with higher soil pH values. At sites where P was not limiting, available P δ 18 O P increased by up to 3‰ when lime was applied. We show that the δ 18 O P method is a useful tool to investigate the effect of pH on soil P cycling under field conditions as it highlights that different soil processes must govern P availability as pH shifts. The next challenge is now to identify these underlying processes, enabling better management of soil P at different pH.

Rationale: Phosphorus losses from agriculture pose an environmental threat to watercourses. A new approach using the stable oxygen isotope ratio of oxygen in phosphate (δ 18 O PO4 value) may help elucidate some phosphorus sources and cycling. Accurately determined and isotopically distinct source values are essential for this process. The δ 18 O PO4 values of animal wastes have, up to now, received little attention., Methods: Phosphate (PO 4 ) was extracted from cattle faeces using anion resins and the contribution of microbial PO 4 was assessed. The δ 18 O PO4 value of the extracted PO 4 was measured by precipitating silver phosphate and subsequent analysis on a thermal conversion elemental analyser at 1400°C, with the resultant carbon monoxide being mixed with a helium carrier gas passed through a gas chromatography (GC) column into a mass spectrometer. Faecal water oxygen isotope ratios (δ 18 O H2O values) were determined on a dual-inlet mass spectrometer through a process of headspace carbon dioxide equilibration with water samples., Results: Microbiological results indicated that much of the extracted PO 4 was not derived directly from the gut fauna lysed during the extraction of PO 4 from the faeces. Assuming that the faecal δ 18 O H2O values represented cattle body water, the predicted pyrophosphatase equilibrium δ 18 O PO4 (Eδ 18 O PO4 ) values ranged between +17.9 and +19.9‰, while using groundwater δ 18 O H2O values gave a range of +13.1 to +14.0‰. The faecal δ 18 O PO4 values ranged between +13.2 and +15.3‰., Conclusions: The fresh faecal δ 18 O PO4 values were equivalent to those reported elsewhere for agricultural animal slurry. However, they were different from the Eδ 18 O PO4 value calculated from the faecal δ 18 O H2O value. Our results indicate that slurry PO 4 is, in the main, derived from animal faeces although an explanation for the observed value range could not be determined., (© 2018 The Authors. Rapid Communications in Mass Spectrometry Published by John Wiley & Sons Ltd.)

The need to reduce both point and diffuse phosphorus pollution to aquatic ecosystems is widely recognised and in order to achieve this, identification of the different pollutant sources is essential. Recently, a stable isotope approach using oxygen isotopes within phosphate (δ 18 O PO4 ) has been used in phosphorus source tracing studies. This approach was applied in a one-off survey in September 2013 to the River Taw catchment in south-west England where elevated levels of phosphate have been reported. River water δ 18 O PO4 along the main channel varied little, ranging from +17.1 to +18.8‰. This was no >0.3‰ different to that of the isotopic equilibrium with water (Eδ 18 O PO4 ). The δ 18 O PO4 in the tributaries was more variable (+17.1 to +18.8‰), but only deviated from Eδ 18 O PO4 by between 0.4 and 0.9‰. Several potential phosphate sources within the catchment were sampled and most had a narrow range of δ 18 O PO4 values similar to that of river Eδ 18 O PO4 . Discharge from two waste water treatment plants had different and distinct δ 18 O PO4 from one another ranging between +16.4 and +19.6‰ and similar values to that of a dairy factory final effluent (+16.5 to +17.8‰), mains tap water (+17.8 to +18.4‰), and that of the phosphate extracted from river channel bed sediment (+16.7 to +17.6‰). Inorganic fertilizers had a wide range of values (+13.3 to +25.9‰) while stored animal wastes were consistently lower (+12.0 to +15.0‰) than most other sources and Eδ 18 O PO4 . The distinct signals from the waste water treatment plants were lost within the river over a short distance suggesting that rapid microbial cycling of phosphate was occurring, because microbial cycling shifts the isotopic signal towards Eδ 18 O PO4 . This study has added to the global inventory of phosphate source δ 18 O PO4 values, but also demonstrated the limitations of this approach to identifying phosphate sources, especially at times when microbial cycling is high., (Copyright © 2016 Office national des forêts. Published by Elsevier B.V. All rights reserved.)

In this study, we conduct a spatial analysis of soil total phosphorus (TP), acid extractable phosphate (PO 4 ) and the stable oxygen (O) isotope ratio within the PO 4 molecule (δ 18 O PO 4 ) from an intensively managed agricultural grassland site. Total P in the soil was found to range from 736 to 1952 mg P kg - 1 , of which between 12 and 48% was extractable using a 1 M HCl (HCl PO 4 ) solution with the two variables exhibiting a strong positive correlation. The δ 18 O PO 4 of the extracted PO 4 ranged from 17.0 to 21.6‰ with a mean of 18.8‰ (± 0.8). While the spatial variability of Total P has been researched at various scales, this is the first study to assess the variability of soil δ 18 O PO 4 at a field-scale resolution. We investigate whether or not δ 18 O PO 4 variability has any significant relationship with: (i) itself with respect to spatial autocorrelation effects; and (ii) HCl PO 4 , elevation and slope - both globally and locally. Results indicate that δ 18 O PO 4 was not spatially autocorrelated; and that δ 18 O PO 4 was only weakly related to HCl PO 4 , elevation and slope, when considering the study field as a whole. Interestingly, the latter relationships appear to vary in strength locally. In particular, the δ 18 O PO 4 to HCl PO 4 relationship may depend on the underlying soil class and/or on different field managements that had operated across an historical north-south field division of the study field, a division that had been removed four years prior to this study.

Nerve growth factor (NGF), a neurotrophin, modulates a diverse set of physiologic processes in the nervous, immune, and endocrine systems. Studies suggest that NGF can be measured in saliva (sNGF). Historically, the method for measuring sNGF involves the off-label use of an enzyme immunoassay designed for use with cell-culture supernatants/tissue extracts (Nam et al., 2007; Ruhl et al., 2004). In a series of experiments we reveal this measurement strategy is subject to non-specific interference by constituents present in oral fluids. We conclude that the measurement of sNGF by this assay is not optimal for use with oral fluid specimens., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

Introduction. This study investigated the relationship between suicidal ideation and demographic characteristics, health conditions, depression, and health care utilization patterns among adolescents. Methods. Secondary analysis of the regionally representative Canadian Community Health Survey conducted in 2000/2001 (response rate 85%). Adolescents aged 15 to 19 who reported suicidal ideation in the previous year (n = 260) were compared with their peers who did not (n = 5528). The association between suicidal ideation and socio-demographic and health characteristics were investigated. Findings. Almost three-quarters (73%) of suicidal adolescents had not spoken with any health professional about mental health issues in the preceding year. Despite the fact that 80% of suicidal adolescents had regular contact with their family doctor, only 5% had consulted with them about mental health issues. In addition to the well-known risk factors of depression and stress, suicidal ideation was highly elevated in adolescents with two or more chronic health conditions, self-reported poor health, migraines, and back pain and those whose activities were prevented by pain (P < .05). Other characteristics significantly correlated with suicidal ideation included smoking, living in single parent families, and having lower levels of social support. Conclusions. Family physicians should regularly screen for suicidal thoughts in their adolescent patients with these characteristics.

This paper demonstrates the application of a low-cost and rapid natural fluorescence technique for tracing and quantifying the transport of pollutants from livestock farming through a small headwater catchment. Fluorescence intensities of Dissolved Organic Matter (DOM) present in different pollutant sources and drainage waters in the Den Brook catchment (Devon, UK) were monitored through storm events occurring between January 2007 and June 2008. Contrasting fluorescence signals from different sources confirmed the technique's usefulness as a tracer of pollutants from livestock farming. Changes in fluorescence intensities of drainage waters throughout storm events were used to assess the dynamics of key pollutant sources. The farmyard area of the catchment studied was shown to contribute polluted runoff at the onset of storm events in response to only small amounts of rain, when flows in the Den Brook first-order channel were low. The application of slurry to a field within the catchment did not elevate the fluorescence of drainage waters during storm events suggesting that when slurry is applied to undrained fields the fluorescent DOM may become quickly adsorbed onto soil particles and/or immobilised through bacterial breakdown. Fluorescence intensities of drainage waters were successfully combined with discharge data in a two component mixing model to estimate pollutant fluxes from key sources during the January 2007 storm event. The farmyard was shown to be the dominant source of tryptophan-like material, contributing 61-81% of the total event flux at the catchment outlet. High spatial and temporal resolution measurements of fluorescence, possibly using novel in-situ fluorimeters, may thus have great potential in quickly identifying and quantifying the presence, dynamics and sources of pollutants from livestock farming in catchments., (Copyright © 2011 Elsevier B.V. All rights reserved.)

Evidence for the movement of agricultural slurry and associated pollutants into surface waters is often anecdotal, particularly with relation to its 'particulate' components which receive less attention than 'bio-available' soluble phases. To assess the extent of movement of slurry particles artificial fluorescent particles were mixed with slurry and applied to a field sub-catchment within a headwater catchment. Particles were 2-60 μm in diameter and two different densities, 2.7 and 1.2 g cm(-3) representing 'inorganic' and 'organic' material. Water samples from the field and catchment outlet were collected during two storm events following slurry application and analysed for particle and suspended sediment concentrations (SSC). SSC from the field and catchment outlet always formed clockwise hysteresis loops indicating sediment exhaustion and particles of the two densities were always found to be positively correlated. Particles from the field formed clockwise hysteresis loops during the first discharge event after slurry application, but anti-clockwise hysteresis loops during the second monitored event which indicated a depletion of readily mobilisable particles. Particles from the catchment outlet always formed anticlockwise hysteresis loops. Particle size became finer spatially, between field and catchment outlet, and temporally, between successive storm events. The results indicate that slurry particles may be readily transported within catchments but that different areas may contribute to pollutant loads long after the main peak in SSC has passed. The density of the particles did not appear to have any effect on particle transport however the size of the particles may play a more important role in the 2-60 μm range., (Copyright © 2010 Elsevier B.V. All rights reserved.)

A study was undertaken on drained and undrained 1 ha grassland lysimeters to assess the effectiveness of multiple novel tracing techniques in understanding how agricultural slurry waste moves from land to water. Artificial fluorescent particles designed to mimic the size and density of organic slurry particles were found to move off the grassland via inter-flow (surface + lateral through-flow) and drain-flow. Where both pathways were present the drains carried the greater number of particles. The results of the natural fluorescence and δ13C of water samples were inconclusive. Natural fluorescence was higher from slurry-amended lysimeters than from zero-slurry lysimeters, however, a fluorescence decay experiment suggested that no slurry signal should be present given the time between slurry application and the onset of drainage. The δ13C values of >0.7 microm and <0.7 microm material in drainage were varied and unrelated to discharge. The mean value of >0.7 microm δ13C in water from the drain-flow pathways was higher from the lysimeter which had received naturally enriched maize slurry compared to the lysimeter which received grass slurry indicating a contribution of slurry-derived material. Values of <0.7 microm δ13C from the same pathway, however, produced counter intuitive trends and may indicate that different fractions of the slurry have different δ13C values.

Understanding the fate of dung carbon (C) in soils is challenging due to the ubiquitous presence of the plant-derived organic matter (OM), the source material from which both dung-derived OM and soil organic matter (SOM) predominantly originate. A better understanding of the fate of specific components of this substantial source of OM, and thereby its contribution to C cycling in terrestrial ecosystems, can only be achieved through the use of labelled dung treatments. In this short review, we consider analytical approaches using bulk and compound-specific stable carbon isotope analysis that have been utilised to explore the fate of dung-derived C in soils. Bulk stable carbon isotope analyses are now used routinely to explore OM matter cycling in soils, and have shown that up to 20% of applied dung C may be incorporated into the surface soil horizons several weeks after application, with up to 8% remaining in the soil profile after one year. However, whole soil delta(13)C values represent the average of a wide range of organic components with varying delta(13)C values and mean residence times in soils. Several stable (13)C isotope ratio mass spectrometric methods have been developed to qualify and quantify different fractions of OM in soils and other complex matrices. In particular, thermogravimetry-differential scanning calorimetry-isotope ratio mass spectrometry (TG-DSC-IRMS) and gas chromatography-combustion-IRMS (GC-C-IRMS) analyses have been applied to determine the incorporation and turnover of polymeric plant cell wall materials from C(4) dung into C(3) grassland soils using natural abundance (13)C isotope labelling. Both approaches showed that fluxes of C derived from polysaccharides, i.e. as cellulose or monosaccharide components, were more similar to the behaviour of bulk dung C in soil than lignin. However, lignin and its 4-hydroxypropanoid monomers were unexpectedly dynamic in soil. These findings provide further evidence for emerging themes in biogeochemical investigations of soil OM dynamics that challenge perceived concepts of recalcitrance of C pools in soils, which may have profound implications for the assessment of the potential of agricultural soils to influence terrestrial C sinks., (Copyright 2010 John Wiley & Sons, Ltd.)

Stable isotopes of water have been previously used in catchment studies to separate rain-event water from pre-event groundwater. However, there are a lack of studies at the smaller scale looking at the separation of event water from pre-event water. This is particularly relevant for heavy clay soil systems through which the movement of water is uncertain but is thought to be rainwater-dominated. The data presented here were collected at a rural site in the south-west of England. The historic rainfall at the site was isotopically varied but similar to the global meteoric water line, with annual weighted means of -37 per thousand for delta(2)H and -5.7 per thousand for delta(18)O and with no seasonal variation. Drainage was sampled from the inter-flow (surface runoff + lateral through-flow) and drain-flow (55 cm deep mole drains) pathways of two 1 ha lysimeters during two rainfall events, which had delta(2)H values of -68 per thousand and -92 per thousand, respectively. The delta(2)H values of the lysimeter drainage water suggest that there was no contribution of event water during the first, small discharge (Q) event; however, the second larger event did show isotopic variation in delta(2)H values negatively related to Q indicating that rainwater was contributing to Q. A hydrograph separation indicated that only 49-58% of the inter-flow and 18-25% of the drain-flow consisted of event water. This was surprising given that these soil types are considered retentive of soil water. More work is needed on heavy clay soils to understand better the nature of water movement from these systems., (Copyright 2010 John Wiley & Sons, Ltd.)

The value of natural fluorescence in tracing diffuse pollution, in liquid phase, following slurry application to land was assessed by field experiment using twelve one hectare lysimeters on a heavy clay soil in Devon, UK, during autumn 2007. A strong linear relationship was found between natural fluorescence intensity and slurry concentration. The ratio of indices of tryptophan-like and fulvic/humic-like fluorescence (TI:FI) varied between 2 and 5 for a range of slurries sampled from Devon farms and allowed slurry to be distinguished from uncontaminated drainage waters (TI:FI<1). Incidental losses of slurry, indicated by significantly enhanced TI:FI ratios, high TI and high ammonium levels, occurred via the drain flow pathway of the drained lysimeters during the first small event following slurry-spreading. The maximum estimated loss from a single lysimeter was 2-8kg or 0.004-0.016% of the applied slurry. In the second larger storm event, some five weeks later, significantly enhanced TI:FI ratios in the drain flows were not associated with high TI but with high nitrate levels and, compared to the earlier storm, an increase in the humification index. This implies the loss of slurry decomposition products during this event but further work is needed to validate this. There was no significant enhancement of TI:FI in the surface/throughflow pathways of the drained or undrained lysimeters in either of the events. The observed change over a period of weeks in the strength and nature of the fluorescence signal from spread slurry restricts quantification of slurry losses to those immediately after slurry spreading. Nonetheless, this study demonstrates the utility of fluorescence as an indicator of slurry in drainage waters and the importance of field drains in diffuse agricultural pollution., (Copyright 2009 Elsevier Ltd. All rights reserved.)

The origin of NO(3) (-) yielded in drainage from agricultural grasslands is of environmental significance and has three potential sources; (i) soil organic mater (SOM), (ii) recent agricultural amendments, and (iii) atmospheric inputs. The variation in delta(15)N-NO(3) (-) and delta(18)O-NO(3) (-) was measured from the 'inter-flow' and 'drain-flow' of two 1 ha drained lysimeter plots, one of which had received an application of 21 m(3) of NH(4) (+)-N-rich agricultural slurry, during two rainfall events. Drainage started to occur 1 month after the application of slurry. The concentrations of NO(3) (-)-N from the two lysimeters were comparable; an initial flush of NO(3) (-)-N occurred at the onset of drainage from both lysimeters before levels quickly dropped to <1 mg NO(3) (-)-N L(-1). The isotopic signature of the delta(15)N-NO(3) (-) and delta(18)O-NO(3) (-) during the first two rainfall events showed a great deal of variation over short time-periods from both lysimeters. Isotopic variation of delta(15)N-NO(3) (-) during rainfall events ranged between -1.6 to +5.2 per thousand and +0.4 to +11.1 per thousand from the inter-flow and drain-flow, respectively. Variation in the delta(18)O-NO(3) (-) ranged from +2.0 to +7.8 per thousand and from +3.3 to +8.4 per thousand. No significant relationships between the delta(15)N-NO(3) (-) or delta(18)O-NO(3) (-) and flow rate were observed in most cases although delta(18)O-NO(3) (-) values indicated a positive relationship and delta(15)N-NO(3) (-) values a negative relationship with flow during event 2. Data from a bulked rainfall sample when compared with the theoretical delta(18)O-NO(3) (-) for soil microbial NO(3) (-) indicated that the contribution of rainfall NO(3) (-) accounted for 8% of the NO(3) (-) in the lysimeter drainage at most. The calculated contribution of rainfall NO(3) (-) was not enough to account for the depletion in delta(15)N-NO(3) (-) values observed during the duration of the rainfall event 2. The relationship between delta(15)N-NO(3) (-) and delta(18)O-NO(3) (-) from the drain-flow indicated that denitrification was causing enrichment in the isotopes from this pathway. The presence of slurry seemed to cause a relative depletion in delta(18)O-NO(3) (-) in the inter-flow and delta(15)N-NO(3) (-) in the drain-flow compared with the zero-slurry lysimeter. This may have been caused by increased microbial nitrification stimulated by the presence of increased NH(4) (+)-N., (John Wiley & Sons, Ltd)