Perceptual and Motor Space Representation: An Event-Related Potential Study

The purpose of this experiment was to study the brain potentials generated during spatial tasks related to the “schema corporel” (a mental map of sensory-motor relationships). Seven right-handed subjects performed a choice reaction-time task (Experiment 1), in which the spatial position of a visual stimulus (right or left of a fixation point) was varied independently of the spatial position of the response (right or left hand). The subjects also made self-paced extensions and flexions of the right and left index fingers (Experiment 2). Experiments 1 and 2 were performed with the hands both crossed and uncrossed. Spatio-temporal maps showed that the P300 component elicited by the choice RT situation in Experiment 1 was largest ipsilateral to the hand involved in the response, whether or not the hands were crossed. The later part of the pre-movement potentials during Experiment 2 and the motor potential were significantly larger contralateral to the moving hand under all conditions. Thus this pattern of lateralization can be attributed to the superimposition of a bilateral P300 wave on the asymmetrical motor potential. This suggests that distinct neuronal populations are involved in the generation of these two components. P300 latency and RT reflected the spatial conflict: both were longer when the stimulus and response were on opposite sides than when they were on the same side, even when the hands were crossed. However, the average P300 latency was not increased when the hands were crossed, whereas the average RT was substantially increased. Since the additional time required for programming the movement in the crossed hand situation had no effect on P300 generation, we infer that the P300 does not index this motor programming. However, P300 does reflect the stimulus-response spatial matching, since its latency was delayed by spatial conflict.     

Interaction of a Motor Response, and Reaction Time and Time Estimation Tasks, on Heart Rate and Skin Conductance

The influence of motor responding and typical psychophysiological tasks on heart rate was tested by manipulating motor requirements of reaction time (RT) and time estimation (TE) tasks. Thirty-four volunteers were assigned randomly to four groups. Two groups squeezed a hand dynamometer at the start of a trial and the other two groups squeezed at the finish of the trial. The force of the squeeze was also manipulated: either 3 kg (3) or 7 kg (7). The four groups were Start 3, Start 7, Finish 3, and Finish 7. All subjects participated in the TE and RT tasks. The dependent variables were measurements of forearm flexor muscle tension, heart rate and skin conductance. It was found that the manipulations of when and with what force a person squeezed the dynamometer resulted in reliable group differences in muscle tension. The magnitude of acceleratory components of the triphasic (acceleration-deceleration-acceleration) cardiac response was amplified by tension. The magnitude of the deceleratory component seemed to depend on both muscle tension and stimulus processing. Except for the magnitude of the response-bound deceleration, RT and TE produced very similar heart rate responses, and skin conductance did not differ among groups. The data were interpreted as providing evidence that motor response acts as an amplifier for the phasic HR produced by common psychological paradigms.     

GABA-receptor activation in the globus pallidus and entopeduncular nucleus: opposite effects on reaction time performance in the cat

The possible role of GABAergic mechanisms in the control of the basal ganglia output structures, the globus pallidus (GP) and the entopeduncular nucleus (EP), was studied in cats performing a conditioned flexion movement triggered by an auditory stimulus. The effects of discrete unilateral microinjections of low doses of the GABA_A receptor agonist (muscimol 5–100 ng/ 0.5 l) and antagonist (bicuculline methiodide 25–150 ng/0.5 l) in the GP and the EP were tested on the motor performance of eight animals trained to release a lever in a simple reaction time (RT) schedule after an auditory stimulus. Control injections in neighboring structures did not induce any effect except with five- to tenfold higher doses in the closest injection sites. The dose of 20 ng muscimol injected into the ventral and medial part of the GP produced an arrest of the performance after a few unsuccessful trials (over the RT reinforcement limit of 500 ms), while muscimol injected in sites located in the lateral GP resulted in a dose-dependent lengthening in RTs, with a concomitant increase in the force change latency. In most of the subjects, the force exerted on the lever was higher after muscimol than after vehicle injection. Force change velocity was then significantly increased. In contrast, muscimol injected in the ventral and rostral region of the EP produced a decrease in RTs or a complete cessation of responding after a high number of anticipatory responses (release of the lever before the trigger stimulus). No significant changes in the force change latency could be observed while there was a non-significant tendency for the force levels to be lowered. Bicuculline injections in the EP were found to increase RTs with a concomitant increase in force change latency and a slowness of velocity, while no significant effect was observed following injections in the GP. These results suggest that a balance between GABAergic activity in the two output nuclei of the basal ganglia, the GP and the EP, is crucial for the correct initiation and execution of the conditioned motor task.     

The relative effects of external spatial and motoric factors on the bimanual coordination of discrete movements

The ability to coordinate the two hands effectively is a fundamental requirement for many everyday tasks. To investigate how bimanual coordination is achieved we asked subjects to perform discrete bimanual key-press responses under conditions in which the motoric (i.e., muscles employed) and external spatial (i.e., direction of movement in external space) relationships between the actions of the left and right index fingers were systematically varied. Subjects made simultaneous right and left index finger key-presses in response to an auditory tone. The right finger always made downward flexion movements whilst the left finger either flexed in a downward/upward direction, or extended in a downward/upward direction. Unimanual control trials of each movement type for both hands were also performed. Reaction times for each hand (RTs) and the inter-response interval (IRI) were recorded . Right hand RTs were significantly affected only when the left finger performed motorically different actions, but were unaffected by the external spatial direction in which the left hands actions were made. The IRI results followed a similar pattern with the worst coordination (highest IRI) occurring when the left finger performed different motor actions to the right finger regardless of the direction of the left hand movement. In contrast to other recent results from experiments examining oscillatory tasks (e.g., Mechsner et al. 2001), our results suggest that in discrete tasks there is a dominance of the motor relationship between the hands over the external spatial relationship.     

Cocaine's effects on speech sound identification and reaction times in baboons

The effects of cocaine on speech sound discriminations was examined to determine whether cocaine's previously demonstrated effect in reducing speech sound discriminability was dependent upon either the type of stimuli employed (simple tones versus complex speech) or the procedure (stimulus detection versus stimulus discrimination). Because of demonstrated similarities in the way that baboons and humans discriminate speech, and in the way the CNS is thought to encode and process speech sounds in these two species, baboons were trained to perform a choice procedure to identify the occurrence of different synthetic vowel sounds (/a/, /æ/, //, /U/, and /љ/). Animals held down a lever and released the lever only when one of four target vowels sounded, and not when a fifth, standard vowel sounded. Acute IM administration of cocaine (0.0032–1.0 mg/kg) produced dose-dependent decreases in vowel discriminability that were mostly due to elevations in false alarms (i.e., releases to the standard vowel) following cocaine. Cocaine also shortened reaction times to the stimuli in two of three baboons, but to a much lesser extent than observed previously. These results suggest that cocaine may interfere with the ability of the CNS to process the acoustic cues in speech sounds, and that the effects of cocaine on reaction times may depend upon the complexity of the reaction time procedure employed.     

MYCN AMPLIFICATION IN MEDULLOBLASTOMA

Prominent neuronal differentiation and MYCN amplification occur only in a small percentage of medulloblastomas (primitive neuroectodermal tumor of the cerebellum). In this article, we describe two medulloblastomas that showed a striking degree of neuronal differentiation with islands of mature neurons associated with abundant neuropil. In these differentiated foci, there were no mitoses or atypia, and the histology was reminiscent of a malformative or hamartomatous lesion. Both tumors were assessed for MYCN amplification by the novel technique of differential polymerase chain reaction (PCR) and fluorescent in situ hybridization (FISH). In case 1, MYCN amplification was in the 10 - fold range determined by differential PCR, while in case 2 the level of amplification was marked, with 20 - 30 copies compared with diploid controls. FISH analysis also confirmed the presence of MYCN amplification in both tumors. These two cases are of great interest, especially as they show MYCN amplification in medulloblastomas with marked degree of neuronal differentiation. Furthermore, in both cases, there was evidence of a slower and more indolent clinical course, suggesting a more favorable outcome in medulloblastoma with this degree of neuronal differentiation.     

349例药物不良反应报告分析

目的：观察药品不良反应（ADR）发生情况,探讨药品不良反应发生因素,总结药品不良反应发生规律,促进合理用药。方法：选取349例药品不良反应报告作为研究对象,从患者年龄、性别、药品种类、给药途径、器官损害表现及程度等方面进行统计分析。结果：经调查分析,年龄较大人群有170例（48．71％）,静脉注射、口服给药引起的ADR分别有161例（46．13％）、177例（50．72％）,中药制剂类不良反应发生率为32．95％。结论：增强合理用药意识,完善防范处理方案,指导患者合理服用药物,同时加强ADR监测,保障用药安全。     

保胎灵胶囊临床应用不良反应调查研究

目的：探讨保胎灵胶囊临床应用效果及不良反应发生情况.方法：选取2 700例诊断为先兆早产的孕妇为研究对象.将其随机分为20岁以下组（A组）,21～30岁组（B组）,31岁以上组（C组）三组,每组900例.以同期收治的一般资料差异无显著性的500例先兆早产产妇为对照组.A、B、C组采取保胎灵胶囊联合盐酸利托君治疗,对照组采取盐酸利托君治疗.比较各组患者分娩后成功保胎率、孕期延长时间以及不良反应情况.结果：A、B、C三组产妇在成功保胎率、孕期延长时间、不良反应方面,组间比较差异无统计学意义（P＞0.05）;A、B、C三组产妇在成功保胎率、孕期延长时间、不良反应方面均优于对照组,差异具有统计学意义（P＜0.05）.结论：保胎灵胶囊联合盐酸利托君治疗先兆早产,可以提高保胎率,延长孕期时间,有利于新生婴儿的预后,是一种提高产科质量安全有效的治疗方法,而且其不良反应发生情况和产妇年龄无直接联系,临床上值得推广使用.     

正交设计优选昧连简单序列重复间扩增多太性反应体系的研究

目的 优化味连简单序列重复间扩增多太性(Coptis chinensis Franch.ISSR)反应体系.方法 利用正交实验设计,从Mg2 ,dNTP.引物,BSA这4种因素3个水平进行优化.结果 确立了适合黄连ISSR分析的反应体系,即在25 μl反应体系中,内含1×PCR buffer,1.5 mmol/L Mg2 ,200 μmol/L dNTP,0.4 μmol/L引物,40 ng模板,1U Taq DNA聚合酶,BSA 1 μg/μl.结论 利用此优化反应体系能得到清晰、稳定的图谱.     

精神药物所致呃逆的识别与处理

多种精神药物可引起呃逆,为了提高临床对精神药物所致呃逆的认识,本文对呃逆的定义与原因、精神药物所致呃逆的诊断、鉴别诊断及发病机制等作一综述。