Reward-related stimuli can potently influence behavior; for example, exposure to drug-paired cues can trigger drug use and relapse in people with addictions. Psychological mechanisms that generate such outcomes likely include cue-induced cravings and attentional biases. Recent animal data suggest another candidate mechanism: reward-paired cues can enhance risky decision making, yet whether this translates to humans is unknown. Here, we examined whether sensory reward-paired cues alter decision making under uncertainty and risk, as measured respectively by the Iowa Gambling Task and a two-choice lottery task. In the cued versions of both tasks, gain feedback was augmented with reward-concurrent audiovisual stimuli. Healthy human volunteers (53 males, 78 females) performed each task once, one with and the other without cues (cued Iowa Gambling Task/uncued Vancouver Gambling Task: n ϭ 63; uncued Iowa Gambling Task/cued Vancouver Gambling Task: n ϭ 68), with concurrent eye-tracking. Reward-paired cues did not affect choice on the Iowa Gambling Task. On the two-choice lottery task, the cued group displayed riskier choice and reduced sensitivity to probability information. The cued condition was associated with reduced eye fixations on probability information shown on the screen and greater pupil dilation related to decision and reward anticipation. This pupil effect was unrelated to the risk-promoting effects of cues: the degree of pupil dilation for risky versus risk-averse choices did not differ as a function of cues. Together, our data show that sensory reward cues can promote riskier decisions and have additional and distinct effects on arousal.
Various synthetic derivatives of natural flavonoids are known to have neuroactive properties. The present study aimed to investigate the effects of vitexin (5, 7, 4-trihydroxyflavone-8-glucoside), a flavonoid found in such plants as tartary buckwheat sprouts, wheat leaves phenolome, Mimosa pudica Linn and Passiflora spp, on scopolamine-induced memory impairment in rats. To achieve this goal, we assessed the effects of vitexin on memory retrieval in the presence or absence of scopolamine using a step-through passive avoidance trial. In the first part of the study, vitexin (25, 50, and 100 microM) was administered intracerebroventricularly (i.c.v.) before acquisition trials. In the second part, vitexin, at the same doses, was administered before scopolamine (10 microg, i.c.v.) and before the acquisition trials. During retention tests, vitexin (100 microM) in the absence of scopolamine significantly increased the step-through latencies compared to scopolamine. In addition, vitexin (100 microM) significantly reversed the shorter step-through latencies induced by scopolamine (P < 0.05). These results indicate that vitexin has a potential role in enhancing memory retrieval. A possible mechanism is modulation of cholinergic receptors; however, other mechanisms may be involved in its effects in acute exposure.
Ground motion intensity measures and structural responses are correlated in nearby sites. The value of this correlation relies on some parameters such as the local geology and distance between the two sites and the natural period of structures, particularly, when lifeline systems or distributed structures are of concern, the issue becomes more important. In this study, the spatial correlation of peak ground acceleration and Spectral Acceleration are evaluated as a function of inter-site separation distance for the Mw7.3 Sarpol-e-Zahab earthquake. On 12 November 2017 a large earthquake occurred near the western border of Iran. The epicenter of the earthquake was reported at 34.77 N and 45.76 E. Here, 192 pairs of horizontal components from the above-mentioned event and 35 of its larger aftershocks with magnitude ranging from Mw 4.0 to 7.3 are employed to evaluate the intra-event residual correlation by considering two Ground Motion Prediction Equations (GMPEs) proposed by Akkar and Bommer [2010] and .A correlation analysis is carried out through semivariogram as a powerful geostatistical tool. As a skeleton for correlation modeling, a kind of exponential model is used. According to the proposed model, the results show that the overall trend of correlation Range depends on spectral period. The results demonstrate that there is strong spatial correlation in the proposed model obtained from the Sarpol-e-Zahab ground motions. The model provided in this study could be employed in earthquake engineering implements such as Shakemaps [Wald et al., 1999] whenever spatial correlation models are required.
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