Studies of operant and reflexive key pecks in the pigeon

The duration of pigeons' key pecks was studied in three experiments. Experiment I revealed that key pecks early in exposure to continuous reinforcement were of short duration, as were key pecks observed on an omission procedure in which pecks prevented food delivery. Key pecks later in exposure to continuous reinforcement, and those that occurred on positive automaintenance procedures, were of long duration. In Experiment II, pigeons were exposed to fixed-interval and fixed-ratio reinforcement schedules, and durations were recorded separately for each quarter of each interval or ratio. On fixed interval, durations were shorter in the first quarter of each interval than in subsequent quarters; on fixed ratio, durations were longer in the first quarter of the ratio than in subsequent quarters. These data parallel observations of concurrent operant responding and salivation in dogs. In Experiment III, pigeons were exposed to a discrete trial, differential-reinforcement-of-low-rate 6-sec schedule. Durations of responses in the first 2 sec of the trial were substantially shorter than those of responses that occurred later. The data from all three experiments support the view that the pigeon's "key peck" actually consists of two subclasses of peck, one reflexive and one operant.     

Relationship between the Millon Behavioral Health Inventory and the minnesota multiphasic personality inventory (MMPI) in low-back pain patients

The Millon Behavioral Health Inventory (MBHI) is being used with increasing frequency for the assessment of chronic pain, although there is a relative lack of evidence as to its utility, and prior studies have not examined low back pain. This investigation compared the MBHI to the MMPI in a sample of low-back pain patients and analyzed subgroups of pain patients based upon their MBHI responses. Subjects were 60 patients who had been admitted to outpatient multidisciplinary pain clinics of two Chicago-area hospitals. Patients completed both the MMPI and the MBHI and provided demographic information. Results of correlational analyses indicated strong relationships between the MBHI psychogenic attitude, psychosomatic correlate, and prognostic index scales and the validity scales of the MMPI. The MBHI Pain Treatment Responsivity scale (PP) correlated with 16 of the other 19 MBHI scales. PP did not demonstrate specificity with low back pain patients. The results of both the scale comparisons and the exploratory two-group cluster subgroup analysis support the notion that responses to the MBHI are largely affected by the respondent's tendency to deny psychopathology or to admit emotional distress.     

Negative emotionality and positive/social behavior in rural appalachian infants: Prediction from caregiver and infant characteristics

This study explored stability and change in two aspects of infant temperamental behavior in a sample of 94 economically-disadvantaged rural Appalachian families. Regressions were used to predict Time 2 temperament for infants who increased and dereased in negative emotionality and positive/social behavior. Both infant and caregiving environment factors contributed to explaining change in first-year behavior. In this sample, maternal social support predicted more optimal change in infants' negative emotionality and positive/social behavior. Receiving public assistance and minor perinatal risk were associated with slower decline in negative emotionality and emergence of positive/social behavior.     

Multidimensional Assessment of Chronic Low Back Pain: Predicting Treatment Outcomes

This study explored responses of chronic low back pain patients to treatment for different types of patients (dysfunctional, interpersonally distressed, and minimizer/adaptive coper), as classified using the Multidimensional Pain Inventory (MPI). In addition, changes in MPI scores during treatment were examined separately for each patient type. Finally, this study explored the relationships between changes in MPI scores and physical improvement. Between-group differences in improvement were significant, with dysfunctional patients showing the most improvement on several scales. MPI scales that best predicted physical improvement differed according to patient type. Implications for treatment of low back pain patients are suggested, based upon differential reactions to treatment and different predictors of physical improvement for each patient group.     

Thinking about the self influences thinking in general: cognitive consequences of salient self-concept

Two studies support our hypothesis that connected and interdependent self-focus evokes a generally context-dependent cognitive mode (focused on object-context relations) and provide some evidence that separate and independent self-focus evokes a generally context-independent cognitive mode (focused on objects, independent of contexts). Consistent with our predictions, experimental manipulation of interdependent self-focus influences cognitive speed/accuracy (Experiment 1) and memory (Experiment 2). When primed self-focus is congruent with the perceptual task at hand, perceptual speed increases (as shown by a significant task by prime interaction effect) and when primed, interdependent self-focus improves memory for incidentally encoded contextual information. Further research to link primed and chronic self-focus effects is called for.     

Is pain-related fear a predictor of somatosensory hypervigilance in chronic low back pain patients?

Pain-related fear has been found to be associated with increased disability and increased pain perception in patients with chronic low back pain. A possible mechanism by which pain-related fear could lead to increased pain perception is heightened attention to somatosensory sensations. In the present study, chronic pain patients reporting either a high or low level of pain related fear and control participants performed an auditory reaction time task, while occasionally non-painful electrical stimuli--accompanied by threatening instructions--were given to the arm or back. In the primary task condition, participants had to perform the auditory task while ignoring the electrical stimuli. Next, the task was presented under dual task conditions in which participants had to respond both to tones as well as to detection of electrical stimuli. It was hypothesized that for the primary task, high fearful patients would show greater disruption of performance on the auditory task than low fearful patients and controls when stimuli were presented to the back. For the dual task, slower reaction times for the auditory task, in combination with faster detection of electrical stimuli was expected. The hypotheses were not confirmed but patients scoring high on pain-related fear did show an overall increase in reaction time for all conditions of the primary task, with or without simultaneous stimulation. Regression analyses demonstrated that high pain-related fear was associated with increased reaction time to tones both in patients and healthy controls, and that within patients pain-related fear was a better predictor of reaction time to tones than present pain intensity. The findings may be interpreted as showing that patients with elevated levels of pain-related fear habitually attend to somatic sensations, giving less priority to other attention-demanding tasks.     

低自尊个体对拒绝性信息的注意偏向

自尊是个体对自我的情感性评价, 影响着个体对周围环境的应对方式。低自尊个体由于容易知觉到外部的拒绝性信息, 也更倾向于将别人的行为知觉为拒绝, 因而存在对拒绝性信息的注意偏向。本文首先综述了低自尊个体的认知与行为特点, 其次简单介绍了低自尊个体注意偏向的常用研究范式(Stroop范式、点探测任务、空间线索任务、惊吓探测范式、注意监测任务、注意转移任务), 随后列举了解释低自尊个体注意偏向的理论(社会计量理论、关系图式理论、注意成分说、注意控制说), 最后总结了低自尊个体注意偏向的脑机制研究。未来的研究应更多关注自尊结构的复杂性, 注意偏向的信息加工阶段性及其脑机制, 注意训练的作用机制及低自尊个体注意偏向的本土研究等问题。     

氧化型低密度脂蛋白：致动脉粥样硬化和抗动脉粥样硬化的双重作用

研究证明,氧化型低密度脂蛋白（oxLDL）,而不是低密度脂蛋白,是致动脉粥样硬化的独立危险因素。oxLDL主要通过巨噬细胞上的清道夫受体摄入oxLDL,引起血管壁泡沫细胞的堆积和脂纹的形成;oxLDL还改变了内皮细胞、平滑肌细胞、血小板的多种功能,使之释放多种致炎细胞因子,促进了炎症细胞的趋化和聚集。但最近有报道认为,口服免疫耐量的oxLDL可弱化早期和晚期动脉粥样硬化。因此,oxLDL不仅能导致动脉粥样硬化,在某些情况下,还具有抗动脉粥样硬化的作用。本文从辩证法的角度出发,系统的阐述oxLDL的这一双重作用。     

下腰痛诊治过程中的临床思考

下腰痛是常见疾病,其病因复杂,治疗方法虽多,但并无特效疗法.因此,下腰痛的诊治比较棘手.本文回顾性分析2002年4月至2008年12月因下腰痛住院的936例患者的诊治过程,探讨如何在科学的临床思维指导下,综合运用各种诊断和治疗的方法,提高下腰痛的诊治水平.