The 5-choice serial reaction time task: behavioural pharmacology and functional neurochemistry

Abstract Rationale. The developmental history and application of the 5-choice serial reaction time task (5CSRTT) for measuring effects of drugs and other manipulations on attentional performance (and stimulus control) in rats is reviewed. Objectives. The 5CSRTT has been used for measuring effects of systemic drug treatments and also central manipulations such as neurochemical lesions on various aspects of attentional control, including sustained, selective and divided attention – and is relevant to the definition of neural systems of attention and applications to human disorders such as attention deficit/hyperactivity disorder (ADHD) and Alzheimer's disease. Methods. The 5CSRTT is implemented in a specially designed operant chamber with multiple response locations ('nine-hole box') using food reinforcers to maintain performance on baseline sessions (about 100 trials) at criterion levels of accuracy and trials completed. The 5CSRTT can be used for measuring various aspects of attentional control over performance with its main measures of accuracy, premature responding, correct response latencies and latency to collect earned food pellets. Results. The data reviewed include studies mainly of systemic and intra-cerebral effects of adrenoceptor, dopamine receptor, serotoninergic receptor and cholinergic receptor agents. These are compared with investigations of effects of selective chemical neurotoxins and excitotoxins applied to discrete parts of the forebrain, in order to define the neural and neurochemical substrates of attentional function. Furthermore, these results are integrated with findings from in vivo microdialysis in freely moving rats or metabolic studies. Conclusions. The monoaminergic and cholinergic systems appear to play separable roles in different aspects of performance controlled by the 5CSRTT, in neural systems centred on the prefrontal cortex, cingulate cortex and striatum. These conclusions are considered in the methodological and theoretical context of other psychopharmacological studies of attention in animals and humans. Electronic Publication     

Distributed perfusion educational model: a shift in perfusion economic realities

In recent years, a steady decline in the number of perfusion education programs in the United States has been noted. At the same time, there has been a parallel decline in the number of students graduated from perfusion educational programs in the United States. Also, as noted by several authors, there has been an increase in demand for perfusion graduates. The decline in programs and graduates has also been noted in anesthesia and surgical residency programs. The shift is caused by a combination of economic and clinical factors. First, decreased reimbursement has led to reallocation of hospital resources. Second, the original enthusiasm for beating heart coronary artery bypass surgery was grossly overestimated and has led to further reallocation of hospital resources and denigration of cardiopulmonary bypass. This paper describes two models of perfusion education programs: serial perfusion education model (SPEM) and the distributed perfusion education model (DPEM). Arguments are presented that the SPEM has some serious limitations and challenges for long-term economic survival. The authors feel the DPEM along with dependence on tuition funding can survive the current clinical and economic conditions and allow the profession to adapt to changes in scope of practice.     

Do Myoepithelial Cells Hold the Key for Breast Tumor Progression?

Mammary myoepithelial cells have been a neglected facet of breast cancer biology, largely ignored since they have been considered to be less important for tumorigenesis than luminal epithelial cells from which most of breast carcinomas are thought to arise. In recent years as our knowledge of stem cell biology and the cellular microenvironment has been increasing, myoepithelial cells are slowly starting to gain more attention. Emerging data raise the hypothesis whether myoepithelial cells play a key role in breast tumor progression by regulating the in situ to invasive carcinoma transition and that myoepithelial cells are part of the mammary stem cell niche. Paracrine interactions between myoepithelial and luminal epithelial cells are known to be important for regulation of cell cycle progression, establishing epithelial cell polarity, and inhibiting cell migration and invasion. Based on these functions, normal mammary myoepithelial cells have been called “natural tumor suppressors.” However, during tumor progression myoepithelial cells seem to loose these properties, and eventually this cell population diminishes as tumors become invasive. Better understanding of myoepithelial cell function and their role in tumor progression may lead to their exploitation for cancer therapeutic and preventative measures.     

Quantitative analysis of synaptic distribution along thalamocortical axons in adult mouse barrels

Quantitative data on thalamocortical synapses in adult mouse barrels have been obtained largely by using lesion-nduced degeneration to label thalamic afferents. By the time degenerating axons can be identified with the electron microscope, they have broken up into many separate pieces, making it impossible to assess the distribution of synapses along unbroken lengths of afferent. Here, this deficiency is rectified by examining intact lengths of axon labeled by the injection of biotinylated dextran amine into ipsilateral thalamus. Serial thin section reconstructions were analyzed to determine the numbers of synapses per axon length made with dendritic spines vs. shafts and the locations of synapses with respect to axonal varicosities. Results for seven axonal segments from six mice showed an average of 0.2 synapses/microm; 80% were made with spines and 20% with dendritic shafts. Just over two-thirds of axonal varicosities formed one synapse; most of the remainder formed two and rarely three, whereas 8% formed none. Although most synapses occurred at varicosities (88%), more than 12% were made at cylindrically shaped regions of the reconstructed axonal segments. These results serve as a caveat for the use of light microscopy to quantify synapses, wherein the usual approach is to equate one varicosity with one synapse. For thalamocortical afferents to mouse barrels, equating one varicosity with one synapse would prove to be incorrect more than 30% of the time and would exclude the roughly 12% of synaptic connections made at cylindrical regions of thalamocortical afferents.     

A category-specific advantage for numbers in verbal short-term memory: evidence from semantic dementia

This study explored possible reasons for the striking difference between digit span and word span in patients with semantic dementia. Immediate serial recall (ISR) of number and non-number words was examined in four patients. For every case, the recall of single-digit numbers was normal whereas the recall of non-number words was impaired relative to controls. This difference extended to multi-digit numbers, and remained even when frequency, imageability, word length, set size and size of semantic category were matched for the numbers and words. The advantage for number words also applied to the patients' reading performance. Previous studies have suggested that semantic memory plays a critical role in verbal short-term memory (STM) and reading: patients with semantic dementia show superior recall and reading of words that are still relatively well known compared to previously known but now semantically degraded words. Additional assessments suggested that this semantic locus was the basis of the patients' category-specific advantage for numbers. Comprehension was considerably better for number than non-number words. Number knowledge may be relatively preserved in semantic dementia because the cortical atrophy underlying the condition typically spares the areas of the parietal lobes thought to be crucial in numerical cognition but involves the inferolateral temporal-lobes known to support general conceptual knowledge.     

The meaning of models of nursing to practising nurses

BACKGROUND: It is contended that models of nursing have lost the momentum and challenge that they promised the profession. Their use, value and purpose have been seriously questioned and new perspectives on their use and implementation in practice, education and research are required. In addition, limited evidence exists on the implementation of models into clinical areas. AIM: To explore the meaning of models of nursing to practising nurses. METHODS: Serial interviews with qualified nurses who were undertaking an educational programme or module that explored and examined models of nursing. FINDINGS: The outcome reveals that the use of the terms, models of nursing or nursing model, are limited and confusing as the terms can encompass a range of meanings. It is suggested that a three-model typology exists that clarifies more fully the present position of nursing models. The three models are Theoretical Model, Mental Model and Surrogate Model. LIMITATIONS: The focus on data collection through serial interviews with qualified practitioners could have been broadened to include a range of data sources such as teachers and clinical areas, which could have enriched the phenomenon of models of nursing. CONCLUSIONS: There is a greater need to understand nursing models within the framework of the three-model typology and to reconsider their introduction and use in this context.     

Pain processing within the primary somatosensory cortex in humans

To investigate the processing of noxious stimuli within the primary somatosensory cortex (SI), we recorded magnetoencephalography following noxious epidermal electrical stimulation (ES) and innocuous transcutaneous electrical stimulation (TS) applied to the dorsum of the left hand. TS activated two sources sequentially within SI: one in the posterior bank of the central sulcus and another in the crown of the postcentral gyrus, corresponding to Brodmann's areas 3b and 1, respectively. Activities from area 3b consisted of 20- and 30-ms responses. Activities from area 1 consisted of three components peaking at 26, 36 and 49 ms. ES activated one source within SI whose location and orientation were similar to those of the TS-activated area 1 source. Activities from this source consisted of three components peaking at 88, 98 and 109 ms, later by 60 ms than the corresponding TS responses. ES and TS subsequently activated a similar region in the upper bank of the sylvian fissure, corresponding to the secondary somatosensory cortex (SII). The onset latency of the SII activity following ES (109 ms) was later by 29 ms than that of the first SI response (80 ms). Likewise, the onset latency of SII activity following TS (52 ms) was later by 35 ms than that of area 1 of SI (17 ms). Therefore, our results showed that the processing of noxious and innocuous stimuli is similar with respect to the source locations and activation timings within SI and SII except that there were no detectable activations within area 3b following noxious stimulation.     

科学实施IS09004-2促进医院服务业绩提高

介绍了大庆油田总医院实施ISO9000的背景、具体做法、经验体会和取得的成效。指出,医院实施ISO9000要从实际出发,通过吸收国际上先进的管理思想,提高管理水平。通过管理不断提高服务业绩,使患者、医院、社会和主管部门等相关方获益。医院实施ISO9000要转变管理观念,充分理解和运用2000版ISO9000中所提到的八项质量管理原则,创建医院各相关方共同受益的经营 理念和经营机制,以有效和高效的方式实施管理。提倡预防意识、改进意识和创新意识,围绕“方便、快捷、放心、满意”的质量方针,充分引导全体职工向病人提供及时的、无缺陷的医疗服务。     

Effects of antipsychotic drugs on MK-801-induced attentional and motivational deficits in rats

Background

Attentional deficits that accompany schizophrenia are not effectively treated by available antipsychotic medications. Disruption of NMDA receptor function is often used to model aspects of this disorder in rodents. We used the 5-choice serial reaction time task (5CSRTT) to characterize attentional deficits caused by acute administration or withdrawal from chronic administration of the NMDA receptor antagonist MK-801, and determine if they are ameliorated by haloperidol or clozapine.

Methods

Acute studies involved tests in the presence of MK-801: rats were administered haloperidol (0.008-0.125 mg/kg, SC) or clozapine (0.16-2.5 mg/kg, SC) in combination with MK-801 (0.25 mg/kg, IP) prior to daily test sessions. Chronic studies involved tests in the absence of MK-801: following daily tests, rats were administered MK-801 (0.5 mg/kg, IP) and tested 24 h later in the absence or presence of haloperidol or clozapine.

Results

Acute MK-801 disrupted performance: it decreased accuracy while increasing omissions, premature responses, and magazine entries. Haloperidol reduced disruptive effects associated with increased activation, whereas it exacerbated other deficits. Clozapine dose-dependently attenuated several of the MK-801-induced performance deficits. Withdrawal from chronic MK-801 progressively increased omissions and response latencies and decreased premature responding, suggesting an amotivational state. Neither haloperidol nor clozapine ameliorated these performance deficits.

Discussion

Acute administration and withdrawal from chronic MK-801 administration produced distinct behavioral profiles in the 5CSRTT. Acute MK-801 impaired attention and impulse control whereas chronic MK-801 withdrawal caused signs consistent with amotivation. Haloperidol and clozapine were more effective at attenuating deficits caused by acute MK-801 administration.     

连续型电子出版物审读实践研究

以中华医学会电子版系列杂志审读为例,介绍连续型电子出版物的形式特点、质量问题特点、审读要点,并对连续型电子出版物的主要审查点,如外观标识、使用环境、技术质量、信息呈现、艺术表现及编校质量的规范要求及常见质量问题进行总结分析,以探讨连续型电子出版物的审读方法及质量控制.