Monkey hippocampal neuron responses to complex sensory stimulation during object discrimination.

The purpose of this study was to investigate, during the performance of an object discrimination task, responses of neurons in the monkey hippocampal formation to the sight of several objects that have biological meaning, and compare these responses with those of amygdalar neurons studied previously using the same task. Neuronal activity in the hippocampal formation of conscious monkeys was recorded during performance of a task that led to presentation of familiar rewarding, familiar aversive, or unfamiliar objects. Of 864 neurons recorded in the hippocampal formation and adjacent cortices, 160 (18.5%) responded to the sight of a certain object(s). Responses to the sight of different kinds of objects were analyzed in detail. Nondifferential neurons (n = 73) responded to different objects with no significant difference in response magnitudes, and differential neurons (n = 87) responded to different objects with different response magnitudes. Of the differential neurons, 23 responded more strongly to rewarding objects than to other objects (rewarding-object-dominant neurons), but the magnitude of responses to objects did not necessarily correlates with the order of preferences to the objects as determined from observation of animal behavior. Aversive-object-dominant neurons (n = 13) responded more to aversive objects than to other objects. Unfamiliar-object-dominant neurons (n = 7) responded more to unfamiliar objects than to familiar objects. Selective neurons (n = 10) responded selectively to only one object or one category of objects. Fourteen of the rewarding- or averse-object-dominant neurons were tested in extinction or reversal trials. In 12 of 14 neurons, responses to a rewarding or aversive object did not change, or slightly weakened, in extinction or reversal trials. The results suggest the following. (1) Responses of rewarding- or aversive-object-dominant neurons may be involved in object-reward or object-aversion association. However, responses of many of these neurons might reflect past inputs to reinforcement rather than extant emotional processing. (2) Responses of unfamiliar-object-dominant neurons may be involved in recognition of objects based on their familiar or unfamiliar aspects. These results are further discussed and compared with responsiveness of amygdalar neurons.     

Enhanced stimulus-reward learning by intra-amygdala administration of a D3 dopamine receptor agonist

The amygdala is considered to be a critical neural substrate underlying the formation of stimulus-reward associations, and is known to receive substantial innervation from dopaminergic neurons located within the ventral mesencephalon. However, relat- ively little is known about the function of the mesoamygdaloid dopamine projection in stimulus-reward learning. Recently, we have found post-session intra-amygdala microinjections of d-amphetamine to enhance appetitive Pavlovian conditioning as assessed in a discriminative approach task. In the present study, we have examined the effects of dopamine receptor agonists possessing relative selectivity for the D₁, D₂ and D₃ receptor subtypes in order to examine more fully the role of the mesoamygdaloid dopamine projection in stimulus-reward learning. Thus, subjects were trained to associate an initially neutral stimulus (CS⁺) with 10% sucrose reward (US). A second, control stimulus (CS⁻) was also presented but never paired with sucrose reward. In order to measure specifically the conditioned response to CS⁺/CS⁻ presentation, responding during CS and US presentations was measured separately. Immediately following each training session, subjects received bilateral intra-amygdala infusion of 0.1, 1 or 10 nmol/side of SKF-38393, quinpirole or 7-OH-DPAT. Infusions of SKF-38393 or quinpirole were without effect on CS⁺ approach. However, post-session intra-amygdala infusions of 7-OH-DPAT enhanced selectively CS⁺ approach in a dose-dependent fashion. No dose of any drug affected CS⁻approach, US behaviours, or measures of extraneous behaviour. Subsequent acquisition of a novel conditioned instrumental response was also unaffected. Thus, the present data indicate a selective involvement of the D₃ dopamine receptor subtype in the modulation of stimulus-reward learning by the mesoamygdaloid dopamine projection. Received: 12 December 1996 / Final version: 9 April 1997     

构建学习型军队医院的策略

作介绍了该院制定合理的共同愿景，激发医院员工的学习愿望；建设学习型的领导班子，带动员工自觉学习；强化学习过程管理，不断提高学习效果；处理“学”与“用”的关系，保证学习型组织管理模式长久运行等一系列构建学习型医院的基本做法，为探索医院管理新模式提供了参考。     

Linear relationship between the maintenance of hippocampal long-term potentiation and retention of an associative memory.

The hypothesis that the maintenance or decay of an associative memory trace after an extended retention interval is a function of the residual strength of the synapses originally strengthened during learning was examined in a classical conditioning paradigm in which high-frequency stimulation of a hippocampal input--the medial perforant path--served as a conditioned stimulus. Rats received perforant path stimulus-foot shock pairings while engaged in a previously acquired food-motivated lever-pressing task. Conditioned suppression of lever pressing was the behavioral measure of learning and retention of the association. Stimulus trains to the perforant path at an intensity above the threshold for eliciting a population spike induced long-term potentiation of synaptic transmission in the dentate gyrus. Synaptic potentials recorded extracellularly in the dentate gyrus were subsequently monitored for 31 days to examine quantitatively the decay of synaptic potentiation, a period after which retention of the learned association was assessed. All rats learned the association to a similar extent and displayed equivalent amounts of long-term potentiation by the end of conditioning. A slowly decaying function of synaptic potentiation was observed in remembering rats, i.e., rats with high retention performance after the 31-day learning-to-retention interval, while forgetting was associated with a rapid decay of long-term potentiation. Behavioral performance at the long-term memory test was linearly correlated with the amplitude of long-term potentiation maintained just prior to the retention test. The results favor the hypothesis that long-term associative memory depends, at least in part, on the maintenance of elevated synaptic strengths in the pathway activated during learning and suggest a role for the lasting component of long-term potentiation in the maintenance of memory.     

Independent learning among general practice trainees: an initial survey

Self-directed learning is a natural way for adults to learn. Vocational training for general practice is a preparation for unsupervised clinical work that will be supported, in the main, by continuing medical education. This study uses the Self-Directed Learning Readiness Scale to investigate factors influencing readiness for such learning among a sample of general practice trainees. Three principal factors emerged from analysis: enjoyment and enthusiasm for learning; a positive self-concept as a learner and a factor suggesting the possibility of a 'reproducing' orientation to learning. These factors may reflect approaches to learning in general rather than these adopted for professional learning, but offer helpful pointers for the development of both vocational training and of continuing medical education.     

治疗血浓度下抗癫(癎)药对未成熟脑发育影响的实验研究

目的 探讨抗癫(癎)药物(AEDs)在治疗血浓度下对未成熟脑发育的影响.方法 以AEDs血浓度达到临床治疗稳态血浓度为实验剂量,设立健康幼鼠及成年SD大鼠氯硝西泮(CNP)、苯巴比妥(PB)、丙戊酸(VPA)、托吡酯(TPM)实验组及正常对照组(各18只).AEDs灌胃5周,于停药后次日、2周及1个月末,行Morris水迷宫及穿梭箱测试.停药当天记录体重、脑重,海马及额叶组织行苏木素-伊红(HE)、尼氏染色及电镜观察.结果 (1)停药后次日及2周的穿梭箱实验,幼鼠CNP和PB组逃避潜伏期明显长于对照组.即使停药后1个月,幼鼠CNP[(6.05±2.04)s]及PB组[(5.81±1.75)s]与对照组的差异仍有统计学意义[(4.75±2.43)s,P＜0.01].而停药后2周,成年鼠各AEDs组与对照组已无差异;(2)Morris水迷宫实验,分别于停药后次日、2周及1个月,幼鼠CNP和PB组登平台潜伏期均长于对照组.而成年鼠各组登平台潜伏期于停药后2周已无差异;(3)幼鼠CNP组脑重(1.67±0.04)g,PB组脑重(1.66±0.04)g,较对照[(1.75±0.06)g]轻;(4)神经元广泛变性坏死,神经细胞数[CNP组为(76.87±18.60)个/200倍视野,PB组(72.60±17.26)个/200倍视野]较对照少[(109.13±33.73)个/200倍视野,P＜0.01];(5)停药1个月后,PB组幼鼠神经元超微结构仍异常.结论 长期服用PB、CNP可引起未成熟脑学习记忆功能及脑组织病理学持续异常,PB对未成熟脑的损伤存在可能是不易恢复的.     

FQ-I型清创(冲洗)机的研制

介绍一种电脑清创(冲洗)机的工作原理和系统功能。该机由水泵、水箱、压力调节器、温控器、喷枪等组成。操作时仅需打开开关，根据伤口类型调节压力、水温和冲洗水流的方式即可进行伤口冲洗，简单易行、省时省力，特别适合于战时救治。能降低火器伤的感染率、致残率，提高伤口清创冲洗的效率。     

多巴胺受体的结构和功能

多巴胺是大脑中含量最丰富的儿茶酚胺类神经递质。多巴胺作为神经递质调控中枢神经系统的多种生理功能。多巴胺系统调节障碍涉及帕金森病，精神分裂症，Tourette综合征，注意力缺陷多动综合征和垂体肿瘤的发生等。本文综述了多巴胺受体的共同特征和各个受体的独特特征，以及它们在中枢神经系统的分布和功能，重点强调了多巴胺受体与学习记忆的关系。     

Fluctuations in Tumor Blood Flow under Normotension and the Effect of Angiotensin II-induced Hypertension

To elucidate the significance of angiotensin II (AID-induced hypertension chemotherapy, changes of tissue blood flow both in normal subcutis and in tumors (AH109A, LY80) were measured with the hydrogen gas clearance method. A newly-developed anesthetic machine was used to keep the animals' condition constant. Tissue blood flow in normal subcutis and tumors always fluctuated with time under normotension. The nature and the rate of fluctuation in tumor Wood flow were almost identical in two different types of tumors. However, the fluctuation of blood flow in tumor and that in normal subcutis were almost always inversely related when blood flows in these different tissues were measured simultaneously, i.e., when tissue blood flow in normal subcutis decreased, tumor blood flow increased, and vice versa. The findings supported the idea that the connection mode between the tumor vascular bed and normal vascular bed is a parallel circuit. Vascular resistance in the normal vascular bed under All-induced hypertension seemed to be greater than that under normotension, because the All-increased tumor blood flow always exceeded the maximum tumor blood flow under normotension. Due to the fluctuations of tumor blood flow, no-flow or low-flow areas, resistant to delivery of anti-cancer drugs, moved sporadically within the tumor under the normotensive condition. However, good conditions for drug delivery to tumor tissue were induced by All-induced hypertension.     

妊娠压力对大鼠子代早期空间学习记忆能力的影响

【目的】探索妊娠期精神压力对大鼠子代早期空间学习、记忆能力的影响。【方法】实验采取产前束缚压力,建立妊娠期大鼠精神压力暴露模型。然后对子代进行Morris水迷宫测试,分析妊娠期压力对子代早期学习和记忆的影响及性别间的差异,同时检测实验前、后子鼠的血清肾上腺酮的变化。【结果】①在隐蔽平台试验中,对照组的平均潜伏期较实验组短,但差异无显著性(F=0.599,P>0.05)。②在保持力试验中,对照组在原平台所在象限逗留的时间大于实验组,差异有显著性(F=4.588,P<0.05)。③子代血清肾上腺酮的测定结果表明:水迷宫测试前,实验组和对照组相比,差异无显著性(F=0.169,P>0.05);实验后,实验组血清肾上腺酮比对照组高,差异具有显著性(F=6.098,P<0.05)。【结论】①妊娠压力可导致子代学习,记忆能力的改变;②妊娠压力造成子代在应激情况下血清肾上腺酮的过度分泌。③妊娠压力对子代的影响没有明显性别差异。