Speech-associated gestures, Broca’s area, and the human mirror system

Speech-associated gestures are hand and arm movements that not only convey semantic information to listeners but are themselves actions. Broca’s area has been assumed to play an important role both in semantic retrieval or selection (as part of a language comprehension system) and in action recognition (as part of a “mirror” or “observation–execution matching” system). We asked whether the role that Broca’s area plays in processing speech-associated gestures is consistent with the semantic retrieval/selection account (predicting relatively weak interactions between Broca’s area and other cortical areas because the meaningful information that speech-associated gestures convey reduces semantic ambiguity and thus reduces the need for semantic retrieval/selection) or the action recognition account (predicting strong interactions between Broca’s area and other cortical areas because speech-associated gestures are goal-direct actions that are “mirrored”). We compared the functional connectivity of Broca’s area with other cortical areas when participants listened to stories while watching meaningful speech-associated gestures, speech-irrelevant self-grooming hand movements, or no hand movements. A network analysis of neuroimaging data showed that interactions involving Broca’s area and other cortical areas were weakest when spoken language was accompanied by meaningful speech-associated gestures, and strongest when spoken language was accompanied by self-grooming hand movements or by no hand movements at all. Results are discussed with respect to the role that the human mirror system plays in processing speech-associated movements.     

时间知觉的注意调节：一项ERP研究

采用双任务实验范式探讨时间知觉注意调节的动态过程。通过指导语使被试按照比例将注意分配到声音刺激的时间属性与音调属性上,形成对时间因素不同注意程度的五种注意条件,同时记录反应时、错误率和事件相关电位数据。对峰值分析发现,P2注意条件主效应不显著,但多重比较时T（只注意时间）与P（只注意音调）条件差异显著;对CNV平均波幅分析,发现注意条件主效应显著,随着分配在时间属性上的注意的减少,其波幅逐渐降低;对T与P条件的差异波地形图分析发现,波幅最大的区域位于额叶、中央区和顶叶;该差异波的偶极子定位于辅助运动区（额上回、额中回）和顶下小叶。以上结果表明,P2阶段存在时间信息加工;CNV反映时间知觉的注意调节,时间知觉中存在控制加工应该以CNV的出现为指标;辅助运动区可能为时间知觉的核心成分,具有跨通道效应;顶下小叶也与对时间的注意有关,但并不是特异性的。本研究不支持Lewis提出的 “自动”与“认知控制”计时系统理论中 “秒”为两系统分界点以及辅助运动区只属于“自动计时系统”的观点     

Hierarchically organized behavior and its neural foundations: a reinforcement learning perspective

Research on human and animal behavior has long emphasized its hierarchical structure—the divisibility of ongoing behavior into discrete tasks, which are comprised of subtask sequences, which in turn are built of simple actions. The hierarchical structure of behavior has also been of enduring interest within neuroscience, where it has been widely considered to reflect prefrontal cortical functions. In this paper, we reexamine behavioral hierarchy and its neural substrates from the point of view of recent developments in computational reinforcement learning. Specifically, we consider a set of approaches known collectively as hierarchical reinforcement learning, which extend the reinforcement learning paradigm by allowing the learning agent to aggregate actions into reusable subroutines or skills. A close look at the components of hierarchical reinforcement learning suggests how they might map onto neural structures, in particular regions within the dorsolateral and orbital prefrontal cortex. It also suggests specific ways in which hierarchical reinforcement learning might provide a complement to existing psychological models of hierarchically structured behavior. A particularly important question that hierarchical reinforcement learning brings to the fore is that of how learning identifies new action routines that are likely to provide useful building blocks in solving a wide range of future problems. Here and at many other points, hierarchical reinforcement learning offers an appealing framework for investigating the computational and neural underpinnings of hierarchically structured behavior.     

Enhanced divergent thinking and creativity in musicians: a behavioral and near-infrared spectroscopy study

Empirical studies of creativity have focused on the importance of divergent thinking, which supports generating novel solutions to loosely defined problems. The present study examined creativity and frontal cortical activity in an externally-validated group of creative individuals (trained musicians) and demographically matched control participants, using behavioral tasks and near-infrared spectroscopy (NIRS). Experiment 1 examined convergent and divergent thinking with respect to intelligence and personality. Experiment 2 investigated frontal oxygenated and deoxygenated hemoglobin concentration changes during divergent thinking with NIRS. Results of Experiment 1 indicated enhanced creativity in musicians who also showed increased verbal ability and schizotypal personality but their enhanced divergent thinking remained robust after co-varying out these two factors. In Experiment 2, NIRS showed greater bilateral frontal activity in musicians during divergent thinking compared with nonmusicians. Overall, these results suggest that creative individuals are characterized by enhanced divergent thinking, which is supported by increased frontal cortical activity.     

Mirror Neurons and the Evolution of Embodied Language

ABSTRACT— Mirror neurons are a class of neurons first discovered in the monkey premotor cortex that activate both when the monkey executes an action and when it observes the same action made by another individual. These neurons enable individuals to understand actions performed by others. Two subcategories of mirror neurons in monkeys activate when they listen to action sounds and when they observe communicative gestures made by others, respectively. The properties of mirror neurons could constitute a substrate from which more sophisticated forms of communication evolved; this would make sense, given the anatomical and functional homology between part of the monkey premotor cortex and Broca's area (the "speech" area of the brain) in humans. We hypothesize that several components of human language, including some aspects of phonology and syntax, could be embedded in the organizational properties of the motor system and that a deeper knowledge of this system could shed light on how language evolved.     

Multisensory integration in multiple reference frames in the posterior parietal cortex

Spatial information processing takes place in different brain regions that receive converging inputs from several sensory modalities. Because of our own movements—for example, changes in eye position, head rotations, and so forth—unimodal sensory representations move continuously relative to one another. It is generally assumed that for multisensory integration to be an orderly process, it should take place between stimuli at congruent spatial locations. In the monkey posterior parietal cortex, the ventral intraparietal (VIP) area is specialized for the analysis of movement information using visual, somatosensory, vestibular, and auditory signals. Focusing on the visual and tactile modalities, we found that in area VIP, like in the superior colliculus, multisensory signals interact at the single neuron level, suggesting that this area participates in multisensory integration. Curiously, VIP does not use a single, invariant coordinate system to encode locations within and across sensory modalities. Visual stimuli can be encoded with respect to the eye, the head, or halfway between the two reference frames, whereas tactile stimuli seem to be prevalently encoded relative to the body. Hence, while some multisensory neurons in VIP could encode spatially congruent tactile and visual stimuli independently of current posture, in other neurons this would not be the case. Future work will need to evaluate the implications of these observations for theories of optimal multisensory integration.Edited by: Marie-Hélène Giard and Mark Wallace     

The neural basis of mirror symmetry detection: a review

The human visual system is extremely sensitive to the presence of bilateral (mirror) symmetry. In this review, I summarise the results of recent work investigating the neural basis of mirror symmetry detection, focusing in particular on brain stimulation evidence. Overall, available findings converge in pointing to the lateral occipital (LO) complex, especially in the right hemisphere, as a key region causally involved in symmetry detection. Interestingly, they also suggest that another region in the right extrastriate visual cortex, the occipital face area (OFA), is causally implied in symmetry detection, posing an interesting connection at the neural level between visual cortex responses to faces and to symmetry. Finally, this review also considers evidence on haptic symmetry detection in sighted and early blind individuals that points to LO as a multi-modal symmetry-sensitive region, and suggests that symmetry is a salient perceptual feature mediated by LO even when any visual experience is missing.     

从使动句加工的功能性磁共振成像看中文句法加工的独立性

大脑中的句法加工模式是神经认知科学研究的重要课题, 而句法加工是否存在独立性一直是研究者争论较多的问题。有形态标记的英语等印欧语语言的句法可以通过形态变化表现, 而汉语不具备与印欧语有明确对应关系的形态变化, 因此汉语的句法变化几乎不能通过外在形态标记。通过3T场强功能性磁共振成像, 以汉语语义等值使动句为研究材料, 对不依赖形态变化来标记句法变化的汉语句法加工的独立性进行了初步研究。结果显示, 大脑左侧额叶对于汉语句法加工具有重要的作用, 尤其是大脑左侧额叶中回的BA44区和额叶下回的BA47区都对汉语句法加工较为敏感, 这表明即使不通过形态改变来标记句法变化, 汉语句子加工中的句法加工仍然可以被分离, 句法独立性的加工主要由大脑左侧额叶中回及大脑左侧额叶下回等脑区承担, 大脑左侧颞叶并未参与汉语句法的独立性加工。     

大学生问题发现过程的眼动研究

在潜藏式与矛盾式两类问题发现情境中, 以眼动仪为研究工具, 问题发现能力高与低的大学生各20名为被试, 探讨大学生在问题发现总体和4个兴趣区中的眼动特征及其与发现问题数量和质量之间的关系。研究表明：(1)不同能力大学生在不同情境及其兴趣区中的问题发现差异, 能够体现在眼动指标上。回视是反映问题发现能力的敏感指标。回视次数和发现问题数量与质量之间的正相关, 以及在高能力组学生上的优势, 体现了信息的联系和整合性加工在问题发现中具有积极意义。(2)潜藏式问题发现中, 个体平均注视时间更长, 反映其认知加工难度更大。在提供重要信息的区域, 被试会投入更多精力, 表现为在注视时间、注视次数和瞳孔直径大小等指标的上升。(3)眼睛注视区域与发现问题区域间存在对应关系, 显示出“眼随心动”现象。在问题发现的最初和最终阶段, 被试都会出现跨区信息搜寻行为, 分别代表了对问题线索的寻找和最后的检查评估。高能力被试在每个稳定注视阶段的注视时间更短, 这种信息转换的灵活性体现出其信息加工上的优势。动态眼动轨迹分析揭示了单个静态指标难以反映的新特点。