双侧前额皮层的语言功能--用近红外技术研究语言功能的初步实验

本文报告一个用近红外技术进行的语言认知脑成像实验.实验通过脑f血流的变化情况考察了双侧前额皮层对由不同通道输入的,不同语言的各个层次的认知反应.实验结果表明,双侧前额皮层对高层语义加工,包括对篇章的归纳与抽象,具有特殊的功能,这种功能的神经学分布是对称的,这种功能及其对称性不随语言和输入通道的变化而变化.相比之下,前额皮层对读、听语言材料以及听音乐却显得不敏感.局部血流的变化只显示其对上述任务的一般性的注意力控制.     

Cerebral blood flow differences between long-term meditators and non-meditators

We have studied a number of long-term meditators in previous studies. The purpose of this study was to determine if there are differences in baseline brain function of experienced meditators compared to non-meditators. All subjects were recruited as part of an ongoing study of different meditation practices. We evaluated 12 advanced meditators and 14 non-meditators with cerebral blood flow (CBF) SPECT imaging at rest. Images were analyzed with both region of interest and statistical parametric mapping. The CBF of long-term meditators was significantly higher (p < .05) compared to non-meditators in the prefrontal cortex, parietal cortex, thalamus, putamen, caudate, and midbrain. There was also a significant difference in the thalamic laterality with long-term meditators having greater asymmetry. The observed changes associated with long-term meditation appear in structures that underlie the attention network and also those that relate to emotion and autonomic function.     

Advanced age brings a greater reliance on visual feedback to maintain balance during walking

We implemented a virtual reality system to quantify differences in the use of visual feedback to maintain balance during walking between healthy young (n = 12, mean age: 24 years) and healthy old (n = 11, 71 years) adults. Subjects walked on a treadmill while watching a speed-matched, virtual hallway with and without mediolateral visual perturbations. A motion capture system tracked center of mass (CoM) motion and foot kinematics. Spectral analysis, detrended fluctuation analysis, and local divergence exponents quantified old and young adults’ dynamic response to visual perturbations. Old and young adults walked normally with comparable CoM spectral characteristics, lateral step placement temporal persistence, and local divergence exponents. Perturbed visual flow induced significantly larger changes in mediolateral CoM motion in old vs. young adults. Moreover, visual perturbations disrupted the control of lateral step placement and compromised local dynamic stability more significantly in old than young adults. Advanced age induces a greater reliance on visual feedback to maintain balance during waking, an effect that may compensate for degradations in somatosensation. Our findings are relevant to the early diagnosis of sensory-induced balance impairments and also point to the potential use of virtual reality to evaluate sensory rehabilitation and balance training programs for old adults.     

The Conceptualization of Team Flow

Despite the noted potential for team flow to enhance a team's effectiveness, productivity, performance, and capabilities, studies on the construct in the workplace context are scarce. Most research on flow at the group level has been focused on performance in athletics or the arts, and looks at the collective experience. But, the context of work has different parameters, which necessitate a look at individual and team level experiences. In this review, we extend current theories and essay a testable, multilevel model of team flow in the workplace that includes its likely prerequisites, characteristics, and benefits.     

实验诊断临床思维程序的必要性及其内容

为提高临床实验诊断的效率和准确性,提出编写“实验诊断临床思维程序”的观点。从实验诊断学的特性及发展趋势方面论述了该程序的必要性,并初步拟定了包括项目选择、结果判断和结果应用三个部分的实验诊断临床思维程序。     

Prior expectation and the interpretation of natural language quantifiers

Abstract

The interpretation of natural language quantifiers depends, in part, on one's prior expectations about what the proportion being described might be. This hypothesis is tested empirically, by comparing the interpretation of 10 different quantifier expressions in three contexts which contained proportions about which subjects' expectations were reliably different (Experiment 1). It is further argued that quantifiers perform many functions which cannot be observed by considering only the proportion(s) denoted by a quantifier. The experimental evidence presented shows that quantifiers can provide information about what the user of the quantifier had expected before “knowing the facts” (Experiment 2). It is also clear that when writers produce a quantifier, they can reveal their assumptions about the prior expectations held by their readers (Experiment 2).     

Event-related cerebral hemodynamics reveal target-specific resource allocation for both “go” and “no-go” response-based vigilance tasks

Transcranial Doppler sonography was used to measure cerebral blood flow velocity (CBFV) in the right and left cerebral hemispheres during the performance of a 50-min visual vigilance session. Observers monitored a simulated flight of unmanned aerial vehicles for cases in which one of the vehicles was flying in an inappropriate direction relative to its cohorts. Two types of vigilance tasks were employed: a traditional task in which observers made button press (“go”) responses to critical signals, and a modification of the traditional task called the Sustained Attention to Response Task (SART) in which “go” responses acknowledged nonsignal events and response withholding (“no-go”) signified signal detection. Signal detections and global CBFV scores declined over time. In addition, fine-grained event-related analyses revealed that the detection of signals was accompanied by an elevation of CBFV that was not present with missed signals. As was the case with the global scores, the magnitude of the transient CBFV increments associated with signal detection also declined over time, and these findings were independent of task type. The results support the view of CBFV as an index of the cognitive evaluation of stimulus significance, and a resource model of vigilance in which the need for continuous attention produces a depletion of information-processing assets that are not replenished as the task progresses. Further, temporal declines in the magnitude of event-related CBFV in response to critical signals only is evidence that the decrement function in vigilance is due to attentional processing and not specific task elements such as the required response format.     

Application of the Theory of Signal Detectability to Kinesthetic Discrimination Tasks

The psychophysical methods of the theory of signal detectability were applied to the measurement of kinesthetic recognition sensitivity. Subjects (n = 12) were tested on a kinesthetic discrimination apparatus, and were randomly assigned to one of four treatment conditions. Each subject operated under five response criteria which were imposed through a priori probabilities of high and low kinesthetic stimuli. The fundamental assumptions of the theory of signal detectability were tested and the basic premises of normality and equality of variance observed in most cases. A subproblem investigated the relationship between kinesthetic recognition sensitivity and the two independent variables of direction and extent of forearm movement, but no relationship was observed. This study was conducted at Kansas State University under the direction of Richard H. Cox with technical assistance from Harold L. Hawkins. The study was funded by a Faculty Research Grant awarded by Kansas State University.     

The relationship between blushing propensity,social anxiety and facial blood flow during embarrassment

To investigate blushing in relation to blushing propensity scores and core elements of social anxiety, facial blood flow was monitored in 86 normal volunteers during an embarrassing task (singing a children's song). Increases in facial blood flow were greater in women than men, as were scores on the Blushing Propensity and Fear of Negative Evaluation scales. In addition, high scores on the Blushing Propensity and Social Interaction Anxiety scales were associated with large increases in facial blood flow during singing. However, this appeared to be due primarily to social anxiety because the association between blushing propensity scores and changes in facial blood flow disappeared when social interaction anxiety scores were taken into account. These findings suggest that people generally base their beliefs about blushing on cues other than changes in facial blood flow. Social anxiety may augment increases in facial blood flow during embarrassment, independently of expected or perceived blushing.