Concurrent-chains schedules as a method to study choice between alcohol-associated conditioned reinforcers

An extensive body of research using concurrent-chains schedules of reinforcement has shown that choice for one of two differentially valued food-associated stimuli is dependent upon the overall temporal context in which those stimuli are embedded. The present experiments examined whether the concurrent chains procedure was useful for the study of behavior maintained by alcohol and alcohol-associated stimuli. In Experiment 1, rats responded on concurrent-chains schedules with equal variable-interval (VI) 10-s schedules in the initial links. Across conditions, fixed-interval schedules in the terminal links were varied to yield 1∶1, 9∶1, and 1∶9 ratios of alcohol delivery. Initial-link response rates reflected changes in terminal-link schedules, with greater relative responding in the rich terminal link. In Experiment 2, terminal-link schedules remained constant with a 9∶1 ratio of alcohol delivery rates while the length of two equal duration initial-link schedules was varied. Preference for the rich terminal link was less extreme when initial links were longer (i.e., the initial-link effect), as has been previously reported with food reinforcers. This result suggests that the conditioned reinforcing value of an alcohol-associated stimulus depends on the temporal context in which it is embedded. The concurrent-chains procedure and quantitative models of concurrent chains performance may provide a useful framework within which to study how contextual variables modulate preference for drug-associated conditioned reinforcers.     

How do Motor Systems Deal with the Problems of Controlling Three-Dimensional Rotations?

Rotations are fundamental to motor control, not only for orienting to stimuli but also in the joint articulations that underlie translational movements. Studying three-dimensional (3-D) rotations of the simplest joint system, the eye, has provided general insights into the neural control of movement. First, in selecting one 3-D eye orientation for each two-dimensional (2-D) gaze direction, the oculomotor system generates a behavior called Listing's law that constrains eye position to a 2-D plane, Listing's plane. This selection is made internally by an inverse kinematic transformation called the Listing's law operator. Second, the oculomotor system incorporates the inherent multiplicative relationship between rotational velocity and position to generate the 3-D movement and position commands required by Listing's law. Finally, the coordinate systems for these commands appear to align with Listing's plane rather than with anatomic structures. Recent investigations have revealed similar behavioral constraints in the orientations of the head and arm, suggesting that the neural mechanisms for Listing's law may have analogues in many motor systems.     

A survey of smoking status and cancer risk perceptions among participants attending a hospital-based head and neck screening program

Abstract

Screening for head and neck cancer is underutilized. Given that lack of knowledge of the risk factors may partially account for screening underutilization. we surveyed subjective risk and knowledge of risk factors for head and neck cancer among 124 individuals who attended a free. hospital-based head and neck cancer screening. Few participants were current smokers. Most attendees perceived their risk as similar to others of their age and sex. Personal health habits comprised almost all of the risk-decreasing factors, yet less than half of the risk-increasing factors. generated. Personal habits were less frequently endorsed than factors such as pollution and heredity. Those who mentioned a risk behavior, or a family cancer history, reported higher subjective risk. Those who mentioned a personal health habit reported lower subjective risk. Results highlight needed efforts to increase screening among high-risk individuals through targeted education messages.     

Changes over time in head and neck cancer patients’ and caregivers’ illness perceptions and relationships with quality of life

Objective: This study investigated changes in illness perceptions from diagnosis to six months later in patients with head and neck cancer (HNC) and their caregivers. The study also examined whether discrepancy in patient and caregiver perceptions at diagnosis predicted patient health-related quality of life (HRQL) at six months.

Design: Forty-two patient–caregiver dyads completed the Brief Illness Perception Questionnaire (Brief IPQ) at diagnosis and again six months later. Patients also completed a HRQL questionnaire at both time points. Analyses were performed using the Actor–Partner Interdependence Model.

Main Outcome Measure: Total patient HRQL assessed by the Functional Assessment of Cancer Therapy (FACT-H&N).

Results: Perceptions of emotional impact and illness concern reduced over time in patients and caregivers. Perceptions of treatment control and identity increased in caregivers only. After controlling for the effects of baseline HRQL, and the individual contribution of patient and caregiver illness perceptions, greater discrepancy in perceptions of timeline, personal control, and illness identity among dyads at diagnosis predicted lower patient HRQL at six-month follow-up.

Conclusion: Patients’ and their caregivers’ perceptions of HNC are dynamic over time. Greater discrepancy between patients’ and caregivers’ illness perceptions at diagnosis predict poorer subsequent patient HRQL.     

On the examination couch: the relationship between the egocentric perspective and the attentional focus

Determined by anatomical characteristics, the binocular visual field has an elliptical shape. Whereas the focus of attention – that area of the visual field in which objects can be consciously perceived – is significantly smaller, its shape is not necessarily dependent on the same factors. Indeed, it is yet unknown if the maximum extents of the attentional focus’ meridians are dimensionally stable or adapt to the egocentric perspective. In this study, we intended to measure the expansion up to which peripheral stimuli can still be perceived while participants were sitting and lying on the left and on the right body side. Results demonstrate that contrary to the visual field the maximum extents along the attentional focus’ meridians remain stable across different head positions with a greater horizontal than vertical alignment. This indicates that the expansion ratios of the meridians of the attentional focus are not dependent on the egocentric perspective. Rather, they appear stable in space and gravity-based. Findings are discussed in terms of our visual environment and current as well as alternative interpretations are weighed against each other.     

班主任教师班级管理效能感对学生学习态度及其与学业效能间关系的影响

研究目的在于验证班主任教师的班级管理效能感对学生学习态度等方面有正向预测作用及其对学生学业效能和学习态度间的关系具有调节作用的假设。通过对109个班级的班主任教师和3066名三到六年级的小学生进行问卷调查,多层线性模型(HLM)分析结果表明:(1)在控制学生性别影响时,学生的学习态度、学习方法和学习技术存在显著的班级水平差异;学生学业效能对学生学习态度、学习方法和学习技术有显著的预测作用,且这一影响强度存在显著的班级水平差异。(2)在控制教师所教年级的影响下,班主任教师班级管理效能的高低对学生学习态度、学习方法和学习技术的班级差异具有显著的预测作用,班主任教师班级管理效能感高的班级,学生学习态度越积极;(3)班主任教师班级管理效能感对学生学业效能与学生学习态度和学习方法之间的关系具有显著的调节作用,班主任教师班级管理效能感越高,学生学业效能对学习态度和学习方法的影响越弱,反之班主任教师管理效能感低的班级,学生学业效能感对学习态度的影响较大。     

辩证思维在头颈肿瘤诊治过程中的应用

辩证思维贯穿于整个临床诊疗过程中,每位医师在做出临床决策时,均自觉或不自觉地遵循着该原理。在头颈肿瘤的临床实践中,也应始终遵循辩证思维,使哲学思维和科学思维密切结合。合理、正确地运用辩证思维方法有助于深入认识头颈肿瘤疾病的发生、发展及演变过程,从而采取合理、有效的治疗措施。     

AGGRESSION AS POSITIVE REINFORCEMENT IN MICE UNDER VARIOUS RATIO‐ AND TIME‐BASED REINFORCEMENT SCHEDULES

There is evidence suggesting aggression may be a positive reinforcer in many species. However, only a few studies have examined the characteristics of aggression as a positive reinforcer in mice. Four types of reinforcement schedules were examined in the current experiment using male Swiss CFW albino mice in a resident—intruder model of aggression as a positive reinforcer. A nose poke response on an operant conditioning panel was reinforced under fixed‐ratio (FR 8), fixed‐interval (FI 5‐min), progressive ratio (PR 2), or differential reinforcement of low rate behavior reinforcement schedules (DRL 40‐s and DRL 80‐s). In the FR conditions, nose pokes were maintained by aggression and extinguished when the aggression contingency was removed. There were long postreinforcement pauses followed by bursts of responses with short interresponse times (IRTs). In the FI conditions, nose pokes were maintained by aggression, occurred more frequently as the interval elapsed, and extinguished when the contingency was removed. In the PR conditions, nose pokes were maintained by aggression, postreinforcement pauses increased as the ratio requirement increased, and responding was extinguished when the aggression contingency was removed. In the DRL conditions, the nose poke rate decreased, while the proportional distributions of IRTs and postreinforcement pauses shifted toward longer durations as the DRL interval increased. However, most responses occurred before the minimum IRT interval elapsed, suggesting weak temporal control of behavior. Overall, the findings suggest aggression can be a positive reinforcer for nose poke responses in mice on ratio‐ and time‐based reinforcement schedules.     

胰头癌外科治疗体会

总结提高胰头癌手术切除率、手术技巧和治疗效果的经验。回顾性分析自2003年9月起收治的39例胰头癌病人的临床资料,术中采用解剖性探查、蚊式钳勾划技术,对36例病人全部一次性行胰十二指肠切除术(PD)。手术切除率92.31%,剥离出的癌灶侵犯血管壁的断缘组织中镜下见到癌细胞25.93%,淋巴结转移率47.22%;胰周神经节、丛侵犯率55.56%,并发症发生率25.00%。解剖性探查、蚊式钳勾划技术的应用显著提高胰十二指肠切除率。