Inter-individual neural differences in movement imagery abilities

ObjectivesBuilding on mounting evidence distinguishing the neurological basis of different movement imagery abilities (visual versus kinesthetic), this study compared brain activity (i.e., blood flow changes) through functional magnetic resonance imaging elicited by movement imagery in participants self-reporting good and poor imagery abilities with the Movement Imagery Questionnaire-3. Participants also completed the Vividness of Movement Imagery Questionnaire-2. Method: Thirty-seven females (good imagery ability = 18; poor imagery ability = 19) were randomly presented with four experimental conditions (i.e., Kinesthetic, Internal Perspective, External Perspective and Rest) counterbalanced for condition, during three separate 11-min functional brain scans. Results: Kinesthetic and visual (internal/external) subscale mean differences of the Vividness of Movement Imagery Questionnaire-2 favored good imagers and high Movement Imagery Questionnaire-3 inter-scale correlations evidenced convergent validity. As in prior published work, kinesthetic, internal, and external visual imagery elicited distinct patterns of brain activation relative to rest. Overall, the patterns of brain activity in the good and poor imager groups were remarkably similar, indicating that they both generally relied on a similar brain network during movement imagery. Conclusions: Contrary to processing efficiency hypotheses (i.e., neural efficiency hypothesis) we report that during kinesthetic imagery and external visual imagery only, good imagers actually activated a greater number of spatially distinct cortical sites than did poor imagers. Furthermore, research is needed to fully characterize the neural signature of movement imagery in good and poor imagers. Such research is critical to the appropriate creation and proper application of neuroscience-inspired movement imagery-based learning interventions in healthy and clinical populations.     

捡了西瓜，就该丢掉芝麻吗——浅谈医源性Wernicke脑病

探讨医源性Wernicke脑病（WE）的病因、临床及磁共振图像特点,回顾性分析6例医源性WE病例。医源性WE病前均有禁食史,其临床表现多样。磁共振图像为中脑导水管周围T2WI及Flair高信号。大部分病例补充维生素B1后可好转。提示医源性禁食导致体内维生素B1耗竭是医源性WE的病因,及时补充维生素B1是预防及治疗本病的关键。     

Are errors differentiable from deceptive responses when feigning memory impairment? An fMRI study

Previous neuroimaging studies have suggested that the neural activity associated with truthful recall, with false memory, and with feigned memory impairment are different from one another. Here, we report a functional magnetic resonance imaging (fMRI) study that addressed an important but yet unanswered question: Is the neural activity associated with intentional faked responses and with errors differentiable? Using a word list learning recognition paradigm, the findings of this mixed event-related fMRI study clearly indicated that the brain activity associated with intentional faked responses was different to the activity associated with errors committed unintentionally. For intentional faked responses, significant activation was found in the ventrolateral prefrontal cortex, the posterior cingulate region, and the precuneus. However, no significant activation was observed for unintentional errors. The results suggest that deception, in terms of feigning memory impairment, is not only more cognitively demanding than making unintentional errors but also utilizes different cognitive processes.     

Moving hands, moving entities

In this study we investigated with a priming paradigm whether uni and bimanual actions presented as primes differently affected language processing. Animals’ (self-moving entities) and plants’ (not self-moving entities) names were used as targets. As prime we used grasping hands, presented both as static images and videos. The results showed an interference effect with unimanual action primes (both static and moving) with plants’ names. No modulation of responses for animals’ names was found. We argue that in the present task plants elicit information on unimanual grasping actions they support, while the lack of effect for animals could be due to them being better characterized as active agents.     

多目标追踪的神经机制

多目标追踪任务是研究动态场景中视觉注意加工机制常用的范式。自1998年开始对多目标追踪神经机制的影像学研究以来, 研究者采用ERP和fMRI等技术对多目标注意追踪所涉及的神经电生理活动和脑功能区激活方面开展了大量研究。ERP研究发现, 追踪过程持续的ERP脑电成分如N2pc、CDA的波幅与注意追踪负荷有关, 并且出现在目标与非目标上的探测刺激诱发的脑电成分如N1、P1波幅的差异可反映注意资源的分配, 具体为目标在追踪过程中得到了激活, 而非目标受到了抑制。fMRI研究比较一致地发现了顶叶(包括前顶内沟、后顶内沟、顶上小叶)、背外侧额叶皮层等在注意追踪中的强烈激活。其中顶内沟主要与注意负荷有关, 顶内沟的活动水平直接决定了观察者注意追踪的行为表现。而顶上小叶可能更多的负责注意转移。背外侧额叶皮层可能负责追踪时的感觉运动预测过程。     

高场强MR和CT在急性脑出血中的诊断价值比较

对临床72例急性期脑出血分别进行CT及MR检查,通过脑内血肿量测定及两住有经验诊断医生的分析诊断,比较两项检查的诊断敏感性,探讨高场强MR在诊断急性脑出血中的价值。测量所得MR各序列和CT血肿量差异无统计学意义。敏感性比较T2＊WI和CT组差异无统计学意义,P〈0．01。T1WI和T2WI序列的敏感性相对较差,与CT组比较差异有统计学意义,P〈0．01。MR梯度回波T2＊WI对诊断急性脑内血肿的敏感性和CT检查相当,结合常规扫描序列在急性期脑内血肿的诊断和鉴别诊断中具有实际应用价值。     

多线索语篇阅读中影响背景信息通达的因素

先前的研究发现,在语篇阅读中,背景信息的通达会受到情景的限制,本研究采用实时窗口阅读技术,通过双人物线索材料,进一步探讨影响这种限制作用的因素。在实验所用材料中,配角只是被提及而未在故事情景中出现,其特征描述与目标句中主角的行为形成冲突关系,以配角特征为探测句,要求被试进行意义判断。结果发现,目标句中主角的行为激活了配角的特征描述,使目标句后探测句的反应时显著短于目标句前的反应时,说明起限制作用的所谓"情景"并非故事所发生的"真实情景",而是读者根据故事所建立的"心理情景"。     

Variability in subcortical aphasia is due to variable sites of cortical hypoperfusion

A variety of fluent and nonfluent aphasias have been reported after left basal ganglia stroke. It has been speculated that this heterogeneity may reflect variations in cortical hypoperfusion resulting from large vessel stenosis. To test this hypothesis, a consecutive series of 24 patients with left caudate infarct identified with diffusion-weighted imaging underwent language testing and perfusion-weighted imaging < 24h from onset of symptoms. Specific regions in perisylvian cortex were rated for the percentage of the region that was hypoperfused. Aphasia type was determined on the basis of speech fluency, comprehension, and repetition performance on the language tests. Association between aphasia type/language impairment and regions of hypoperfusion were identified with Fisher's exact tests. Results demonstrated that in patients with acute left caudate infarct, the presence and type of aphasia reflected regions of hypoperfusion, and generally followed predictions based on chronic lesion studies, regarding anatomical lesions associated with classic aphasia types.     

The Moral Contours of Empathy

Morally contoured empathy is a form of reasonable partiality essential to the healthy care of dependents. It is critical as an epistemic aid in determining proper moral responsiveness; it is also, within certain richly normative roles and relationships, itself a crucial constitutive mode of moral connection. Yet the achievement of empathy is no easy feat. Patterns of incuriosity imperil connection, impeding empathic engagement; inappropriate empathic engagement, on the other hand, can result in self-effacement. Impartial moral principles and constraints offer at best meager protection against these perils, and hence serve poorly in securing morally contoured empathy. More nuanced and practical guidance should be sought in normatively substantive conceptions of our roles and relationships and their defining moral stakes. These, joined with more abstract moral tools, can facilitate rich, narratively textured interpretations of moralitys demands. While the content of our normative conceptions must be continually debated, engaging in this debate is vital to the achievement of proper empathy, and thus to effective, respectful, morally healthy care of dependents.This paper was originally presented at the conference on Reasonable Partiality at the Vrije Universiteit, Amsterdam, October 22–24, 2003. I wish to thank all those present for stimulating discussion. Special thanks go to Bert Musschenga, who organized the conference, and who has provided insightful feedback on this paper. Warm thanks as well to Brenda Almond and Bernie Rollin for lively exchanges on the issues addressed here and to Nancy Sherman for sharing with me an ongoing fascination with, and her own fantastic work on, empathy. Comments from an anonymous reviewer for the journal were challenging and helpful. Finally, I wish to express gratitude beyond normal bounds to Maggie Little both for her generosity, keen insight, and artful intervention at key points in this essays evolution and for her ground-breaking work on deontic pluralism that deeply influences the position I frame here.     

Myelin breakdown mediates age-related slowing in cognitive processing speed in healthy elderly men

Background

To assess the hypothesis that in a sample of very healthy elderly men selected to minimize risk for Alzheimer’s disease (AD) and cerebrovascular disease, myelin breakdown in late-myelinating regions mediates age-related slowing in cognitive processing speed (CPS).

Materials and methods

The prefrontal lobe white matter and the genu of the corpus callosum myelinate later in brain development (late-myelinating white matter; LMWM) and are more vulnerable to breakdown due to the effects of normal aging. An in vivo MRI biomarker of myelin integrity (transverse relaxation rates; R₂) of LMWM was obtained for 38 very healthy elderly adult men (mean age = 66.3 years; SD = 6.0; range = 55–76). To evaluate regional specificity, we also assessed a contrasting early-myelinating region (splenium of the corpus callosum; SWM), which primarily contains axons involved in visual processing. CPS was assessed using the Trail Making Test.

Results

LMWM R₂ and CPS measures were significantly correlated (r = .515, p = .0009), but no significant association between R₂ and CPS was detected in the splenium (p = .409). LMWM R₂, but not SWM R₂, was a significant mediator of the relationship between age and CPS (p = .037).

Conclusions

In this very healthy elderly sample, age-related slowing in CPS is mediated by myelin breakdown in highly vulnerable late-myelinating regions but not in the splenium.