Cocaine self-administration decreases type 5 metabotropic glutamate receptor (mGluR5) tissue concentrations in laboratory rats during early abstinence. These changes are thought to influence the ...drug's reinforcing properties and the ability of drug-related cues to induce relapse. Here, our goal was to measure brain regional mGluR5 availability in recently abstinent cocaine dependent humans. Participants meeting DSM-IV diagnostic criteria for current cocaine dependence (n=9) were recruited from the general population. mGluR5 availability (binding potential, non-displaceable; BPND) was measured with high-resolution positron emission tomography (PET HRRT) and 11CABP688. Compared to age- and sex-matched healthy controls (n=9), cocaine dependent subjects showed significantly lower BPND values in the ventral (bilateral: −28.2%, p=0.011), associative (right: −21.4%, p=0.043), and sensorimotor striatum (bilateral: −21.7%, p=0.045), amygdala (left: −26%, p=0.046) and insula (right: −23.3%, p=0.041). Among the cocaine users, receptor availabilities were related to abstinence (range: 2 to 14days). The longer the duration of abstinence, the lower the BPND values in the sensorimotor striatum (r=−0.71, p=0.034), left amygdala (r=−0.73, p=0.026) and right insula (r=−0.67, p=0.046). Compared to healthy controls, BPND values were significantly reduced in those who tested negative for cocaine on the PET test session in the ventral (p=0.018) and sensorimotor striatum (p=0.017), left amygdala (p=0.008), and right insula (p=0.029), but not in those who tested positive. Together, these results provide evidence of time-related mGluR5 alterations in striatal and limbic regions in humans during early cocaine abstinence.
•mGluR5 has been proposed to modulate the reinforcing properties of cocaine.•We measured mGluR5 availability in cocaine dependents using 11CABP688 PET ligand.•Cocaine use was associated with lower mGluR5 levels in the limbic system.•Longer abstinence from cocaine was associated with lower mGluR5 availability.•Changes in mGluR5 might reflect changes in susceptibility to drug use and relapse.
This research examined how stakeholders (
n
= 40) from one school district experienced “accountability” within a context where responsibility for student learning was being distributed across the ...system. Using a case study design, we examined: what conditions supported stakeholders in multiple roles to exercise responsibility for student learning? Analyses of documents and interviews revealed conditions that enabled teachers, instructional leaders, and administrators to share responsibility in relation to their roles, and empowered teachers to engage in inquiry for continuous improvement and build from their sense of professionalism and responsibility. Implications are discussed for empowering teachers, and other stakeholders, to exercise responsibility in the context of an accountability system.
Timely forecasting of aboveground vegetation biomass is crucial for effective management and ensuring food security. However, research on predicting aboveground biomass remains scarce. Artificial ...intelligence (AI) methods could bridge this research gap and provide early warning to planners and stakeholders. This study evaluates the effectiveness of deep learning (DL) algorithms in predicting aboveground vegetation biomass with limited-size data. It employs an iterative forecasting procedure for four target horizons, comparing the performance of DL models—multi-layer perceptron (MLP), long short-term memory (LSTM), gated recurrent unit (GRU), convolutional neural network (CNN), and CNN-LSTM—against the traditional seasonal autoregressive integrated moving average (SARIMA) model, serving as a benchmark. Five limited-size vegetation biomass time series from Kenyan grasslands with values at 15-day intervals over a 20-year period were chosen for this purpose. Comparing the outcomes of these models revealed significant differences (p < 0.05); however, none of the models proved superior among the five time series and the four horizons evaluated. The SARIMA, CNN, and CNN-LSTM models performed best, with the statistical model slightly outperforming the other two. Additionally, the accuracy of all five models varied significantly according to the prediction horizon (p < 0.05). As expected, the accuracy of the models decreased as the prediction horizon increased, although this relationship was not strictly monotonic. Finally, this study indicated that, in limited-size aboveground vegetation biomass time series, there is no guarantee that deep learning methods will outperform traditional statistical methods.
Eight healthy men underwent two positron emission tomography (PET) 11Craclopride scans, one following placebo, the second following d-amphetamine (0.30 mg/kg, p.o.). PET data were analyzed using: (1) ...brain parametric maps to statistically generate regions of significant change; and (2) a priori identified regions of interest (ROI) manually drawn on each individual's co-registered magnetic resonance (MR) images. Compared with placebo, d-amphetamine decreased 11Craclopride binding potential (BP) with significant effects in ventral but not dorsal striatum. Change in BP in the statistically generated cluster correlated with self-reported drug-induced ‘drug wanting’ (r = 0.83, p = .01) and the personality trait of Novelty Seeking-Exploratory Excitability (r = 0.79, p = .02). The same associations were seen in the manually drawn ROI in ventral striatum but not in dorsal putamen or caudate. Changes in extracellular dopamine (DA) did not correlate with mood. Mesolimbic DA might mediate interest in obtaining reward rather than reward, per se. Individual differences in amphetamine-induced DA release might be related to predispositions to drug and novelty seeking.
Critical participatory action researchers (CPAR) (Kemmis et al., 2014; Ledwith & Springett, 2014) created conditions for 25 parents and teachers to join as co-researchers in this research study. ...Together, they co-created a hybrid discursive third space (Gee, 1996; Gutierrez, 2008) that invited alignment of their respective funds of knowledge (Gonzalez et al., 2005). Participants engaged in iterative processes of conscientization (Freire, 1976) through story, dialogue, and reflections that led to a convergence of teaching and parenting through relational connectivity and metaphoric bridges of togetherness and trust disrupting previously held institutionalized and unquestioned hegemonic borders, rules, and roles.
Rates of serotonin synthesis were measured in the human brain using positron emission tomography. The sensitivity of the method is indicated by the fact that measurements are possible even after a ...substantial lowering of synthesis induced by acute tryptophan depletion. Unlike serotonin levels in human brain, which vary greatly in different brain areas, rates of synthesis of the indolamine are rather uniform throughout the brain. The mean rate of synthesis in normal males was found to be 52% higher than in normal females; this marked difference may be a factor relevant to the lower incidence of major unipolar depression in males.
Dysregulation of the stress response system is a potential etiological factor in the development of and relapse to multiple neuropsychiatric disorders. Previously we reported that repeated ...intermittent d-amphetamine administration can lead to progressively greater dopamine release, thereby providing evidence of drug-induced neurochemical sensitization. Here, we test the hypothesis that repeated exposure to d-amphetamine increases dopaminergic responses to stress; that is, produces cross-sensitization. Using positron emission tomography, we measured in 17 healthy male volunteers (mean ± s.d. = 22.1 ± 3.4 years) (11)Craclopride binding responses to a validated psychosocial stress task before and 2 weeks after a regimen of repeated d-amphetamine (3 × 0.3 mg kg(-1), by mouth; n = 8) or placebo (3 × lactose, by mouth; n = 9). Mood and physiological measurements were recorded throughout each session. Before the d-amphetamine regimen, exposure to the stress task increased behavioral and physiological indices of stress (anxiety, heart rate, cortisol, all P ⩽ 0.05). Following the d-amphetamine regimen, the stress-induced cortisol responses were augmented (P < 0.04), and voxel-based analyses showed larger stress-induced decreases in (11)Craclopride non-displaceable binding potential across the striatum. In the placebo group, re-exposure to stress led to smaller clusters of decreased (11)Craclopride binding, primarily in the sensorimotor striatum (P < 0.05). Together, this study provides evidence for drug × stress cross-sensitization; moreover, random exposure to stimulants and/or stress cumulatively, while enhancing dopamine release in striatal areas, may contribute to a lowered set point for psychopathologies in which altered dopamine neurotransmission is invoked.
Current techniques to reduce the cover of highly flammable plant communities are expensive and often contravene current environmentally friendly policies. Livestock browsing is a less aggressive ...and/or less expensive alternative for controlling shrub encroachment and reducing the risk of forest fires. We evaluated the effect of direct application of two secondary agro-industrial by-products (goat whey and salt from the Iberian ham manufacturing process) on browsing of rosemary by goats. Following application of each treatment, the phytovolume, total biomass, fine fuel biomass and branch biomass of rosemary plants were calculated. Addition of by-products increased browsing of rosemary by goats. The effect on phytovolume and accumulated biomass loss was lower in the whey treatment than in the salt treatments. This decrease was influenced by changes in the fine fuel category values, which were lower in the treated individuals than in the control individuals. Untreated rosemary plants showed no evidence of browsing. The addition of both agro-industrial by-products significantly increased the extent of browsing in treated rosemary and thus reduced the total accumulated biomass (mainly the most flammable parts of the plant).
•The addition of secondary agro-industrial by-products increased rosemary browsing.•The phytovolume loss was significantly higher in individuals impregnated with salt.•Salt treatment was associated with a significant reduction in biomass.•Whey and salt treatments promoted a decrease in biomass classified as most flammable.
Brain regional serotonin synthesis can be estimated in vivo using positron emission tomography (PET) and α-((11))Cmethyl-L-tryptophan ((11)C-AMT) trapping (K*) as a proxy. Recently, we reported ...evidence of lower normalized (11)C-AMT trapping in the orbitofrontal cortex (OBFC) of subjects meeting the criteria for an impulsive and/or aggressive behavioral phenotype. In this study, we examined whether part of the variance in OBFC serotonin synthesis is related to polymorphisms of the gene that encodes for the indoleamine's rate-limiting enzyme in the brain, tryptophan hydroxylase-2 (TPH(2)). In all, 46 healthy controls had PET (11)C-AMT scans and were genotyped for 11 single-nucleotide polymorphisms (SNPs) distributed across the TPH(2) gene and its 5' upstream region. Several TPH(2) SNPs were associated with lower normalized blood-to-brain clearance of (11)C-AMT in the OBFC. Dose-effect relationships were found for two variants (rs6582071 and rs4641527, respectively, located in the 5' upstream region and intron 1) that have previously been associated with suicide. Associations in the OBFC remained statistically significant in a mixed larger sample of patients and controls. These results suggest that in humans, genetic factors might partly account for variations in serotonin synthesis in the OBFC.
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