2003年诺贝尔医学奖给科学界的多重启示(上)

2003年诺贝尔医学奖授予了两位美英物理学家,劳特布尔和曼斯菲尔德,表彰他们在磁共振成像方面的发现.这些发现导致现代磁共振技术的开发,这一技术标志着医学诊断学和科学研究中的一项突破.该项发现建筑在核磁和核磁共振现象被发现的基础之上.核磁现象的发现及其应用导致了1943、1944和1952年诺贝尔物理学奖的获得.核磁共振现象的发现及其应用导致了1991年和2002年诺贝尔化学奖的获得.这意味着,2003年诺贝尔医学奖是该系列发现中第六个诺贝尔科学奖.     

语篇理解中背景信息的激活: 情景限制的共振过程

该研究采用双人物线索语篇材料,对语篇理解中背景信息激活过程的共振模型与剧景模型进行检验。实验一发现,如果主角和配角一直同时在故事情景中成为主线索,则目标句中主角的行为可以激活那些经过屏蔽的、与这一行为相关的配角特征。在实验二中,配角只是在特征描述段落中出现,而后通过适当的描述使其在故事情景中消失,使主角成为故事的主线索,结果发现,此时目标句中主角的行为并不会激活经过屏蔽的配角的特征描述。这些结果表明,背景信息的激活虽然具有共振的特点,但共振并不是无范围限制的,而是一种情景限制下的共振。     

Functional recovery of skilled forelimb use in rats obliged to use the impaired limb after grafting of the frontal cortex lesion with homotopic fetal cortex

The long-term effect of transplanting embryonic frontal cortex into a unilateral frontal cortex lesion has been studied in adult rats. Before surgery, activity in an open field, muscular strength of both forelimbs, and performance in a paw-reaching-for-food task were scored in 26 rats. In 21 animals a unilateral cortex lesion was then made in the forelimb motor area of the hemisphere contralateral to the preferred paw in the paw-reaching-for-food task, while the other 5 animals were sham-operated. On retesting, the lesion animals changed the preferred paw. A solid homotopic transplant of embryonic tissue (embryonic day 17) was then placed in the lesion cavity in 11 of the lesion rats. Three months later neither lesion alone nor lesion plus transplantation affected open field behavior and muscular strength, but the lesion permanently affected performance in the paw-reaching-for-food task, as shown by a change of preferred paw and a functional deficit in the paw contralateral to the lesion. Transplantation ameliorated the deficits caused by the lesion, but this was only evident when animals were forced to reach with the paw contralateral to the lesion plus transplant. The behavioral results were independent of the size of the lesion and graft. Connections between graft and host tissue were studied by means of the fluorescent tracer 1,1'-dioctadecyl-3,3,3'3'-tetramethylindocarbocyanine perchlorate (DiI). A dense array of labeled fibers was found in the host cortex adjacent to the transplant. The results suggest that functional recovery depends on grafting but is only evident when the animal is obliged to use the affected limb.     

带状记忆仪的研制

本文介绍了一种最新研制的适用于师范类大专院校教育及心理专业的心理学实验教学装置"带状记忆仪".     

Adaptation in Visuomanual Tracking Depends on Intact Proprioception

The role of arm proprioception in motor learning was investigated in experiments in which, by moving the arm, subjects followed the motion of a target displayed on a monitor screen. Adaptive capabilities were tested in visuomanual tracking tasks following alterations in the relationship between the observer's actual arm movement and visual feedback of the arm movement given by a cursor motion on the screen. Tracking performance and adaptive changes, measured in terms of spatiotemporal error, tracking trajectory curvature, and spatial gain, were compared in 7 control subjects (CSs) and in 1 deafferented subject (DS). CSs adapted appropriately to altered visuomanual relationships; those changes were present in trials immediately after restoration of normal scaling. In contrast, although the DS modified his tracking strategy from trial to trial according to the altered conditions, he did not show plastic changes in internal visuomanual scaling. Like the results of prismatic adaptation experiments, the present results suggest that arm proprioception contributes to the plastic changes that follow alterations in the scaling of visuomanual gain.     

Effect of Aging on Processes of Motor Inhibition

The processes of inhibiting uninstructed motor responses were examined to identify age differences. Younger adults (n = 40) and older adults (n = 38) participated in two experiments using the Stimulus‐Response Compatibility task. They were asked to push the switch on the side contralateral to the stimulus. The results indicated that responses induced by visual stimuli were gradually inhibited as a result of repeated trials on the contralateral (not‐induced) side, and no age differences were noted. The addition of a color‐discrimination task to the Stimulus‐Response Compatibility task inhibited impulsive response induced by visual stimuli in younger adults only. These results indicate that certain processes of inhibiting motor responses are affected by aging, whereas other processes remain unaffected.     

Dopamine regulation of human speech and bird song: a critical review

To understand the neural basis of human speech control, extensive research has been done using a variety of methodologies in a range of experimental models. Nevertheless, several critical questions about learned vocal motor control still remain open. One of them is the mechanism(s) by which neurotransmitters, such as dopamine, modulate speech and song production. In this review, we bring together the two fields of investigations of dopamine action on voice control in humans and songbirds, who share similar behavioral and neural mechanisms for speech and song production. While human studies investigating the role of dopamine in speech control are limited to reports in neurological patients, research on dopaminergic modulation of bird song control has recently expanded our views on how this system might be organized. We discuss the parallels between bird song and human speech from the perspective of dopaminergic control as well as outline important differences between these species.     

Reinforcing saccadic amplitude variability

Saccadic endpoint variability is often viewed as the outcome of neural noise occurring during sensorimotor processing. However, part of this variability might result from operant learning. We tested this hypothesis by reinforcing dispersions of saccadic amplitude distributions, while maintaining constant their medians. In a first experiment we reinforced the least frequent saccadic amplitudes to increase variability, and then reinforced the central part of the amplitude distributions to reduce variability. The target was placed at a constant distance from the fovea after the saccade to maintain the postsaccadic visual signal constant and an auditory reinforcement was delivered depending on saccadic amplitude. The second experiment tested the effects of the contingency. We reinforced high levels of variability in 4 participants, whereas 4 other participants were assigned to a yoked control group. On average, saccadic amplitude standard deviations were doubled while the medians remained mostly unchanged in the experimental participants in both experiments, and variability returned to baseline level when low variability was reinforced. In the control group no consistent changes in amplitude distributions were observed. These results, showing that variability can be reinforced, challenge the idea of a stochastic neural noise. We instead propose that selection processes constrain saccadic amplitude distributions.     

睡眠对知觉与动作序列内隐学习离线巩固效应的影响

离线阶段发生的学习被称为离线巩固, 即在最初获得知识之后, 即使没有额外的练习, 其记忆痕迹也会保持稳定或提高。有研究初步探究了睡眠对知觉和动作序列内隐学习离线巩固的影响, 然而, 这些研究未能实现知觉序列与动作序列的完全分离, 序列类型是否调节睡眠对内隐序列学习离线巩固的影响仍需进一步探讨。此外, 既往外显学习的研究发现相对于简单的序列, 复杂的序列更容易从睡眠中获益, 表现出基于睡眠的离线巩固效应。睡眠对知觉序列与动作序列内隐学习离线巩固的影响是否会受到序列复杂程度的调节尚不明确。为此, 本研究在完全分离知觉序列和动作序列的情况下, 通过3个实验操纵序列的长度及结构, 设置3种不同复杂程度的序列规则, 考察了这一问题。结果发现, 对于动作序列, 序列规则复杂程度较低时, 无论是否经过睡眠都会发生离线巩固效应, 而当动作序列规则较为复杂时, 只有经历睡眠才会引起离线巩固效应; 对于知觉序列, 无论何种难易程度的规则, 均未发生离线巩固效应。上述结果表明内隐序列知识基于睡眠的离线巩固会受到序列类型及序列复杂程度的调节, 这为内隐学习的离线巩固争论提供了新的视角。     

Investigating the dose-response relationship between motor imagery and motor recovery of upper-limb impairment and function in chronic stroke: A scoping review

The recovery of upper-limb impairment and dysfunction post-stroke is often incomplete owing to the limited time in therapy focused on upper-limb recovery and the severity of the impairment. In these cases, motor imagery (MI) may be used as a precursor to physical therapies to initiate rehabilitation early on when it would be otherwise impossible to engage in therapy, as well as to increase the dose of therapy when MI is used in adjunct to physical therapy. While previous reviews have shown MI to be effective as a therapeutic option, disparity in findings exists, with some studies suggesting MI is not an effective treatment for post-stroke impairment and dysfunction. One factor contributing to these findings is inconsistency in the dose of MI applied. To explore the relationship between MI dose and recovery, a scoping review of MI literature as a treatment for adult survivors of stroke with chronic upper-limb motor deficit was performed. Embase, Medline and CINHAL databases were searched for articles related to MI and stroke. Following a two-phase review process, 21 papers were included, and data related to treatment dose and measures of impairment and function were extracted. Effect sizes were calculated to investigate the effect of dosage on motor recovery. Findings showed a high degree of variability in dosage regimens across studies, with no clear pattern for the effect of dose on outcome. The present review highlights the gaps in MI literature, including variables that contribute to the dose-response relationship, that future studies should consider when implementing MI.