选择性颞叶梗塞对鼠学习记忆能力影响的定量研究

应用光化学的方法选择性诱导颞叶梗塞,同时测定学习记忆能力、神经功能缺失及梗塞面积。结果表明：颞叶梗塞鼠的学习记忆能力显著受损,但无明显感觉运动障碍;颞叶梗塞鼠的学习记忆受损程度与梗塞面积大小有关。结果提示选择性颞叶梗塞是一种理想的痴呆动物模型。     

动画呈现速度对多媒体学习效果影响的眼动研究

多媒体学习过程中,动画学习材料的呈现速度是影响学习效果的一个重要因素。基于认知负荷理论,已有研究对动画速度是否影响多媒体学习中的注意转换和学习效果存在不一致的结论。研究采用闪电形成原理动画作为实验材料,操纵慢速、正常速度和快速三个速度水平,利用Eyelink 1000眼动仪记录学习过程中的眼睛注视,探讨多媒体学习中动画呈现速度对学习效果和注意转换的影响。结果发现,在记忆测验的成绩上,慢速水平的迁移测验成绩要好于正常速度和快速;慢速在注视次数、眼跳次数、任务相关区停留时间和进出兴趣区次数这些总体眼动指标上比其他两组显著要高,但是对相关指标按时间进行加权后发现,只在兴趣区停留时间上慢速和快速长于正常速度。结论认为多媒体学习过程中,动画呈现速度会影响学习的理解效果,但是对识记不产生影响;材料呈现速度影响知识深层次加工,它独立于学习者的注意转换。并且材料呈现速度对学习者眼动的影响是微弱的。     

物理大小和面积的无意识空间表征

意识水平的研究发现,数字量的比较机制与物理刺激比较的机制是一样的;在无意识水平上的研究发现,数字加工存在无意识语义启动现象。我们假设,在数字的物理特性的比较任务中可能存在无意识启动效应和类SNARC效应。实验一的数字比较任务和数字的物理大小比较任务发现,在33毫秒的无意识启动条件下,数字语义比较任务和数字物理大小比较任务中都发现了类SNARC效应、启动效应以及Stroop效应。实验二的数字覆盖面积比较任务中发现,在33毫秒的启动水平,数字比较与数字覆盖面积的比较任务中均存在SNARC效应、Stroop效应和启动效应。     

大脑视觉词形区及其在阅读神经网络中的作用

大脑梭状回中部被认为是视觉词形加工区(Visual Word Form Area, VWFA)。近年来的研究对VWFA的功能提出了质疑, 研究者开始关注VWFA作为复杂阅读网络的一部分与其它脑区的动态联结机制, 主要集中在三个方面：一是梭状回中部对于视觉词形选择性敏感的本质; 二是它在词汇阅读的神经网络中的作用; 最后是语言经验对于VWFA认知神经功能的塑造作用。结合以上研究的最新进展, 文中指明从动态神经网络的角度揭示大脑功能成为今后认知神经科学研究的最新取向。     

伏隔核和中脑腹侧被盖区内食欲素在吗啡奖赏中的作用

实验采用条件性位置偏爱（CPP）模型考察中脑腹侧被盖区（VTA）和伏隔核壳区（NAcSh）内食欲素（orexin）在吗啡奖赏中的作用。Wistar大鼠分为盐水训练组和吗啡训练组。3轮吗啡（或盐水）匹配训练前,双侧VTA或NAcSh内给予OXR1拮抗剂SB334867（VTA: 0, 1, 5μg;NAcSh: 0, 1, 3μg）;或2轮吗啡（或盐水）匹配训练前NAcSh内给予orexin A（0, 2, 4, 6μg）,观察其对吗啡CPP建立的影响。结果表明,VTA内给予SB334867抑制吗啡CPP建立,并存在剂量效应关系;NAcSh内给予SB334867或orexin A均未影响吗啡CPP建立,而orexin A可增加吗啡处理大鼠的运动性。以上结果表明,VTA和NAcSh内的orexin在吗啡奖赏中扮演的角色不同,可能调控成瘾行为的不同成分     

OSP parameters and the cognitive component of reaction time to a missing stimulus: Linking brain and behavior

This within-subjects experiment tested the relationship between the premotor (cognitive) component of reaction time (RT) to a missing stimulus and parameters of the omitted stimulus potential (OSP) brain wave. Healthy young men (N = 28) completed trials with an auditory stimulus that recurred at 2 s intervals and ceased unpredictably. Premotor RT and Motor RT were measured on active trials that required an immediate response to a missing stimulus. Passive trials required no response in order to measure the complete set of OSP parameters (i.e., onset, rate of rise, amplitude and peak latency). The results showed that faster Premotor RT was strongly associated with a faster rate of rise in the OSP wave. Motor RT was unrelated the OSP parameters. This new evidence is consistent with the occurrence of some common cognitive processes generating behavioral and brain reactions to a missing stimulus.     

Metaphor explanation attenuates the right-hand preference for depictive co-speech gestures that imitate actions

Differential activation levels of the two hemispheres due to hemispheric specialization for various linguistic processes might determine hand choice for co-speech gestures. To test this hypothesis, we compared hand choices for gesturing in 20 healthy right-handed participants during explanation of metaphorical vs. non-metaphorical meanings, on the assumption that metaphor explanation enhances the right hemisphere contribution to speech production. Hand choices were analyzed separately for: depictive gestures that imitate action ("character viewpoint gestures," [McNeill, D. (1992). Hand and mind. What gestures reveal about thought. Chicago: University of Chicago Press.]), depictive gestures that express motion, relative locations, and shape ("observer viewpoint gestures"), and "abstract deictic gestures." It was found that the right-hand over left-hand preference was significantly weaker in the metaphor condition than in the non-metaphor conditions for depictive gestures that imitated action. Findings suggest that the activation of the right hemisphere in the metaphor condition reduces the likelihood of left hemisphere generation of gestures that imitate action, thus attenuating the right-hand preference.     

Functional heterogeneity of inferior frontal gyrus is shaped by linguistic experience

A crosslinguistic, positron emission tomography (PET) study was conducted to determine the influence of linguistic experience on the perception of segmental (consonants and vowels) and suprasegmental (tones) information. Chinese and English subjects (10 per group) were presented binaurally with lists consisting of five Chinese monosyllabic morphemes (speech) or low-pass-filtered versions of the same stimuli (nonspeech). The first and last items were targeted for comparison; the time interval between target tones was filled with irrelevant distractor tones. A speeded-response, selective attention paradigm required subjects to make discrimination judgments of the target items while ignoring intervening distractor tones. PET scans were acquired for five tasks presented twice: one passive listening to pitch (nonspeech) and four active (speech = consonant, vowel, and tone; nonspeech = pitch). Significant regional changes in blood flow were identified from comparisons of group-averaged images of active tasks relative to passive listening. Chinese subjects show increased activity in left premotor cortex, pars opercularis, and pars triangularis across the four tasks. English subjects, on the other hand, show increased activity in left inferior frontal gyrus regions only in the vowel task and in right inferior frontal gyrus regions in the pitch task. Findings suggest that functional circuits engaged in speech perception depend on linguistic experience. All linguistic information signaled by prosodic cues engages left-hemisphere mechanisms. Storage and executive processes of working memory that are implicated in phonological processing are mediated in discrete regions of the left frontal lobe.