Chronic cannabis users are known to be impaired on a test of decision-making, the Iowa Gambling Task (IGT). Computational models of the psychological processes underlying this impairment have the potential to provide a rich description of the psychological characteristics of poor performers within particular clinical groups. We used two computational models of IGT performance, the Expectancy-Valence Learning model (EVL) and the Prospect-Valence Learning model (PVL), to assess motivational, memory, and response processes in 17 chronic cannabis abusers and 15 control participants. Model comparison and simulation methods revealed that the PVL model explained the observed data better than the EVL model. Results indicated that cannabis abusers tended to be underinfluenced by loss magnitude, treating each loss as a constant and minor negative outcome regardless of the size of the loss. In addition, they were more influenced by gains, and made decisions that were less consistent with their expectancies relative to non-using controls.Keywords decision-making; cannabis; Iowa Gambling Task; cognitive modeling Substance abusers often are impaired on laboratory measures of decision-making (Bechara et al., 2001;Petry, 2003;Petry, Bickel, & Arnett, 1998;Rogers et al., 1999). For example, in a laboratory decision-making task known as the Iowa Gambling Task (IGT; Bechara, Damasio, Damasio, & Anderson, 1994), substance abusers often make choices that lead to small, immediate gains at the cost of larger losses over time (S. Grant, Contoreggi, & London, 2000). Cannabis (marijuana) users, like other substance-using populations, perform more poorly than non-using controls on the IGT (Lamers, Bechara, Rizzo, & Ramaekers, 2006;Whitlow et al., 2004), even after prolonged abstinence from the drug (Bolla, Eldreth, Matochik, & Cadet, 2005). This impairment may be due to underlying deficits or differences in psychological processes (e.g., memory impairments, loss insensitivity, etc.), but pinpointing such processes can be difficult with traditional behavioral measures from the IGT. Recent work Address correspondence to: Julie C. Stout, School of Psychology, Psychiatry, & Psychological Medicine, Room 534, Building 17 Clayton Campus, Monash University, Victoria 3800 AUSTRALIA, Tel: +61 3 99053987, Fax: +61 3 99053948, julie.stout@med.monash.edu.au. Publisher's Disclaimer: This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. NIH Public Access NIH-PA Author ManuscriptNIH-PA Author Manuscript NIH-PA Author Manuscript has attempted to disentangle component processes of the IGT by means of computational cognitive models (Buse...

ObjectiveTo investigate the effect of virtual reality (VR) and a tetra-ataxiometric posturography (Tetrax) program on stroke patients with impaired standing balance.MethodsThirty acute stroke patients with impaired standing balance were recruited and randomly assigned to a VR, Tetrax, or control group. All patients received conventional balance training as a baseline; and VR and Tetrax patients received VR or Tetrax treatment, in addition. The primary outcome measures to evaluate the overall standing balance were the Berg Balance Scale (BBS) and the falling index (FI). The secondary outcome measures were the stability index (SI) and the weight distribution index (WDI), which were used to evaluate the balance status according to specific body positions. The FI, SI, and WDI were measured using the Tetrax instrument.ResultsThe BBS and FI scores were improved in all groups, with no significant differences between groups. In open-eyed positions, the VR group showed significantly greater improvement in SI and WDI scores than the control group (p<0.017). In closed-eyed positions, the Tetrax group showed significantly greater improvement in SI and WDI scores than the control group (p<0.017).ConclusionThe inclusion of VR and Tetrax programs did not lead to an overall benefit in balance. VR and Tetrax did, however, demonstrate a benefit in specific positions. A Tetrax program may benefit patients with abnormal proprioceptive function, whereas a VR program may benefit patients with normal sensory function.

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Antidotes for toxicological emergencies can be life-saving. However, there is no nationwide estimation of the antidotes stocking amount in Korea. This study tried to estimate the quantities of stocking antidotes at emergency department (ED). An expert panel of clinical toxicologists made a list of 18 emergency antidotes. The quantity was estimated by comparing the antidote utilization frequency in a multicenter epidemiological study and the nation-wide EDs' data of National Emergency Department Information System (NEDIS). In an epidemiological study of 11 nationwide EDs from January 2009 to December 2010, only 92 (1.9%) patients had been administered emergency antidotes except activated charcoal among 4,870 cases of acute adult poisoning patients. Comparing with NEDIS data, about 1,400,000 patients visited the 124 EDs nationwide due to acute poisoning and about 103,348 adult doses of the 18 emergency antidotes may be required considering poisoning severity score. Of these, 13,224 (1.9%) adult doses of emergency antidotes (575 of atropine, 144 of calcium gluconate or other calcium salts, 2,587 of flumazenil, 3,450 of N-acetylcysteine, 5,893 of pralidoxime, 287 of hydroxocobalamin, 144 of sodium nitrite, and 144 of sodium thiosulfate) would be needed for maintaining the present level of initial treatment with emergency antidotes at EDs in Korea.Graphical Abstract

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