Rapid instructed task learning: A new window into the human brain’s unique capacity for flexible cognitive control

The human ability to flexibly adapt to novel circumstances is extraordinary. Perhaps the most illustrative, yet underappreciated, form of this cognitive flexibility is rapid instructed task learning (RITL)—the ability to rapidly reconfigure our minds to perform new tasks from instructions. This ability is important for everyday life (e.g., learning to use new technologies) and is used to instruct participants in nearly every study of human cognition. We review the development of RITL as a circumscribed domain of cognitive neuroscience investigation, culminating in recent demonstrations that RITL is implemented via brain circuits centered on lateral prefrontal cortex. We then build on this and the recent discovery of compositional representations within lateral prefrontal cortex to develop an integrative theory of cognitive flexibility and cognitive control that identifies mechanisms that may enable RITL within the human brain. The insights gained from this new theoretical account have important implications for further developments and applications of RITL research.     

Inhibition and the right inferior frontal cortex

It is controversial whether different cognitive functions can be mapped to discrete regions of the prefrontal cortex (PFC). The localisationist tradition has associated one cognitive function - inhibition - by turns with dorsolateral prefrontal cortex (DLPFC), inferior frontal cortex (IFC), or orbital frontal cortex (OFC). Inhibition is postulated to be a mechanism by which PFC exerts its effects on subcortical and posterior-cortical regions to implement executive control. We review evidence concerning inhibition of responses and task-sets. Whereas neuroimaging implicates diverse PFC foci, advances in human lesion-mapping support the functional localization of such inhibition to right IFC alone. Future research should investigate the generality of this proposed inhibitory function to other task domains, and its interaction within a wider network.     

人际互动中社会学习的计算神经机制

人类在社会互动中通过他人的行为对他人特质、意图及特定情境下的社会规范进行学习, 是优化决策、维护积极社会互动的重要条件。近年来, 越来越多的研究通过结合计算模型与神经影像技术对社会学习的认知计算机制及其神经基础进行了深入考察。已有研究发现, 人类的社会学习过程能够较好地被强化学习模型与贝叶斯模型刻画, 主要涉及的认知计算过程包括主观期望、预期误差和不确定性的表征以及信息整合的过程。大脑对这些计算过程的执行主要涉及奖惩加工相关脑区(如腹侧纹状体与腹内侧前额叶)、社会认知加工相关脑区(如背内侧前额叶和颞顶联合区)及认知控制相关脑区(如背外侧前额叶)。需要指出的是, 计算过程与大脑区域之间并不是一一映射的关系, 提示未来研究可借助多变量分析与脑网络分析等技术从系统神经科学的角度来考察大尺度脑网络如何执行不同计算过程。此外, 将来研究应注重生态效度, 利用超扫描技术考察真实互动下的社会学习过程, 并更多地关注内隐社会学习的计算与神经机制。     

Laminar cortical dynamics of cognitive and motor working memory, sequence learning and performance: toward a unified theory of how the cerebral cortex works

How does the brain carry out working memory storage, categorization, and voluntary performance of event sequences? The LIST PARSE neural model proposes an answer that unifies the explanation of cognitive, neurophysiological, and anatomical data. It quantitatively simulates human cognitive data about immediate serial recall and free recall, and monkey neurophysiological data from the prefrontal cortex obtained during sequential sensory-motor imitation and planned performance. The model clarifies why spatial and non-spatial working memories share the same type of circuit design. It proposes how laminar circuits of lateral prefrontal cortex carry out working memory storage of event sequences within layers 6 and 4, how these event sequences are unitized through learning into list chunks within layer 2/3, and how these stored sequences can be recalled at variable rates that are under volitional control by the basal ganglia. These laminar prefrontal circuits are variations of visual cortical circuits that explained data about how the brain sees. These examples from visual and prefrontal cortex illustrate how laminar neocortex can represent both spatial and temporal information, and open the way towards understanding how other behaviors derive from shared laminar neocortical designs.     

Developmental outcomes after early prefrontal cortex damage

The neuropsychological bases of cognitive, social, and moral development are minimally understood, with a seemingly wide chasm between developmental theories and brain maturation models. As one approach to bridging ideas in these areas, we review 10 cases of early prefrontal cortex damage from the clinical literature, highlighting overall clinical profiles and real life developmental outcomes. Based on these cases, there is preliminary evidence to support distinctive developmental differences after: (1) dorsolateral, (2) mesial, and (3) orbital-polar prefrontal lesions, for more profound impairments after bilateral damage, and possibly for recovery differences after very early vs. later childhood lesion onset. Further case and group studies are needed to confirm reliable effects of specific lesion locations, the influence of age of lesion onset, and related experiential and treatment variables in determining adult outcomes. Rather than a single underlying deficit associated with early prefrontal cortex damage, we interpret the findings to suggest that it is the altered integration and interplay of cognitive, emotional, self-regulatory, and executive/metacognitive deficits that contribute to diverse developmental frontal lobe syndromes. The findings support the fundamental importance of prefrontal cortex maturation in protracted cognitive, social-emotional, and moral development.     

Neurocognitive mechanisms of cognitive control: the role of prefrontal cortex in action selection, response inhibition, performance monitoring, and reward-based learning

Convergent evidence highlights the differential contributions of various regions of the prefrontal cortex in the service of cognitive control, but little is understood about how the brain determines and communicates the need to recruit cognitive control, and how such signals instigate the implementation of appropriate performance adjustments. Here we review recent progress from cognitive neuroscience in examining some of the main constituent processes of cognitive control as involved in dynamic decision making: goal-directed action selection, response activation and inhibition, performance monitoring, and reward-based learning. Medial frontal cortex is found to be involved in performance monitoring: evaluating outcome vis-a-vis expectancy, and detecting performance errors or conflicting response tendencies. Lateral and orbitofrontal divisions of prefrontal cortex are involved in subsequently implementing appropriate adjustments.     

Prefrontal transcranial direct current stimulation over the right prefrontal cortex reduces proactive and reactive control performance towards emotional material in healthy individuals

The prefrontal cortex plays a crucial role in cognitive processes, both during anticipatory and reactive modes of cognitive control. Transcranial Direct Current Stimulation (tDCS) can modulate these cognitive resources. However, there is a lack of research exploring the impact of tDCS on emotional material processing in the prefrontal cortex, particularly in regard to proactive and reactive modes of cognitive control. In this study, 35 healthy volunteers underwent both real and sham tDCS applied to the right prefrontal cortex in a counterbalanced order, and then completed the Cued Emotion Control Task (CECT). Pupil dilation, a measure of cognitive resource allocation, and behavioral outcomes, such as reaction time and accuracy, were collected. The results indicate that, as compared to sham stimulation, active right-sided tDCS reduced performance and resource allocation in both proactive and reactive modes of cognitive control. These findings highlight the importance of further research on the effects of tDCS applied to the right prefrontal cortex on cognitive engagement, particularly for clinical trials utilizing the present electrode montage in combination with cognitive interventions.     

Attention and cognitive control as emergent properties of information representation in working memory

A hallmark of primate, and particularly human, behavior is cognitive control, the ability to integrate information from a multitude of sources and use that information to flexibly guide behavior in order to achieve an infinite number of goals. The neural mechanisms of cognitive control have yet to be fully elucidated, although the prefrontal cortex is known to play a critical role. Here, I review evidence suggesting that a unifying principle regarding the role of various portions of the prefrontal cortex in a wide range of cognitive tasks is the active maintenance in working memory of different types of currently relevant information-from specific stimulus features, to instructional cues, to motivational goals and contexts. I argue that the key to demonstrating the existence of this domain-dependent organization lies in a better understanding of the nature of the representation of this information and the ways in which this information itself controls cognition and behavior.     

Strength of default mode resting-state connectivity relates to white matter integrity in children

A default mode network of brain regions is known to demonstrate coordinated activity during the resting state. While the default mode network is well characterized in adults, few investigations have focused upon its development. We scanned 9-13-year-old children with diffusion tensor imaging and resting-state functional magnetic resonance imaging. We identified resting-state networks using Independent Component Analysis and tested whether the functional connectivity between the medial prefrontal cortex (mPFC) and posterior cingulate cortex (PCC) depends upon the maturation of the underlying cingulum white matter tract. To determine the generalizability of this relationship, we also tested whether functional connectivity depends on white matter maturity between bilateral lateral prefrontal cortex (lateral PFC) within the executive control network. We found a positive relationship between mPFC-PCC connectivity and fractional anisotropy of the cingulum bundle; this positive relationship was moderated by the age of the subjects such that it was stronger in older children. By contrast, no such structure-function relationship emerged between right and left lateral PFC. However, functional and structural connectivity of this tract related positively with cognitive speed, fluency, and set-switching neuropsychological measures.     

Remembering the time: a continuous clock

The neural mechanisms for time measurement are currently a subject of much debate. This article argues that our brains can measure time using the same dorsolateral prefrontal cells that are known to be involved in working memory. Evidence for this is: (1) the dorsolateral prefrontal cortex is integral to both cognitive timing and working memory; (2) both behavioural processes are modulated by dopamine and disrupted by manipulation of dopaminergic projections to the dorsolateral prefrontal cortex; (3) the neurons in question ramp their activity in a temporally predictable way during both types of processing; and (4) this ramping activity is modulated by dopamine. The dual involvement of these prefrontal neurons in working memory and cognitive timing supports a view of the prefrontal cortex as a multipurpose processor recruited by a wide variety of tasks.     

人工类别学习的认知神经研究

基于类别学习包含类别归纳、分类和认知控制3个子过程的假设, 设计了人工类别学习的新任务, 利用高密度ERP技术并结合偶极子源分析, 从纵向和横向两个方面研究了人工类别学习的神经基础与机制。结果表明, 人工类别学习涉及前扣带回、前额叶皮质和内侧颞叶等关键脑区, 并在时间序列上显示了这些脑区扮演的不同作用。基于当前发现, 我们从时-空水平上讨论了的人工类别学习的认知神经机制。     

The neuropsychology of ventral prefrontal cortex: decision-making and reversal learning

Converging evidence from human lesion, animal lesion, and human functional neuroimaging studies implicates overlapping neural circuitry in ventral prefrontal cortex in decision-making and reversal learning. The ascending 5-HT and dopamine neurotransmitter systems have a modulatory role in both processes. There is accumulating evidence that measures of decision-making and reversal learning may be useful as functional markers of ventral prefrontal cortex integrity in psychiatric and neurological disorders. Whilst existing measures of decision-making may have superior sensitivity, reversal learning may offer superior selectivity, particularly within prefrontal cortex. Effective decision-making on existing measures requires the ability to adapt behaviour on the basis of changes in emotional significance, and this may underlie the shared neural circuitry with reversal learning.     

Anterior cingulate cortex and cognitive control: Neuropsychological and electrophysiological findings in two patients with lesions to dorsomedial prefrontal cortex

Whereas neuroimaging studies of healthy subjects have demonstrated an association between the anterior cingulate cortex (ACC) and cognitive control functions, including response monitoring and error detection, lesion studies are sparse and have produced mixed results. Due to largely normal behavioral test results in two patients with medial prefrontal lesions, a hypothesis has been advanced claiming that the ACC is not involved in cognitive operations. In the current study, two comparably rare patients with unilateral lesions to dorsal medial prefrontal cortex (MPFC) encompassing the ACC were assessed with neuropsychological tests as well as Event-Related Potentials in two experimental paradigms known to engage prefrontal cortex (PFC). These included an auditory Novelty Oddball task and a visual Stop-signal task. Both patients performed normally on the Stroop test but showed reduced performance on tests of learning and memory. Moreover, altered attentional control was reflected in a diminished Novelty P3, whereas the posterior P3b to target stimuli was present in both patients. The error-related negativity, which has been hypothesized to be generated in the ACC, was present in both patients, but alterations of inhibitory behavior were observed. Although interpretative caution is generally called for in single case studies, and the fact that the lesions extended outside the ACC, the findings nevertheless suggest a role for MPFC in cognitive control that is not restricted to error monitoring.     

Neural correlates of learning and working memory in the primate posterior parietal cortex

The posterior parietal cortex has been traditionally associated with coordinate transformations necessary for interaction with the environment and with visual-spatial attention. More recently, involvement of posterior parietal cortex in other cognitive functions such as working memory and task learning has become evident. Neurophysiological experiments in non-human primates and human imaging studies have revealed neural correlates of memory and learning at the single neuron and at the brain network level. During working memory, posterior parietal neurons continue to discharge and to represent stimuli that are no longer present. This activation resembles the responses of prefrontal neurons, although important differences have been identified in terms of the ability to resist stimulation by distracting stimuli, which is more evident in the prefrontal than the posterior parietal cortex. Posterior parietal neurons also become active during tasks that require the organization of information into larger structured elements and their activity is modulated according to learned context-dependent rules. Neural correlates of learning can be observed in the mean discharge rate and spectral power of neuronal spike trains after training to perform new task sets or rules. These findings demonstrate the importance of posterior parietal cortex in brain networks mediating working memory and learning.     

主观价值计算与整合的神经机制及其影响因素

决策在人类社会发展的历程中扮演着非常重要的作用,而对其神经机制的探讨才不过几十年的时间。基于价值的决策理论,强调人们首先计算和表征事物的价值,随后比较和决策。在人脑中负责主观价值计算的神经基础有腹内侧前额叶皮层、眶额皮层以及其他脑区,而负责价值整合的脑区有腹内侧前额叶皮层、眶额皮层、背外侧前额叶皮层等。其中时间和风险的价值计算有着相同的神经基础,并且人脑可以将不同属性以及成本进行整合形成主观价值,按照曲线交互作用范式进行。通过自我控制、注意和认知调节等方法,同样可以调制人们的主观价值大小。未来需要继续强调模式分析、个体差异、老龄化和基因对价值计算的影响。     

双侧前额皮层的语言功能--用近红外技术研究语言功能的初步实验

本文报告一个用近红外技术进行的语言认知脑成像实验.实验通过脑f血流的变化情况考察了双侧前额皮层对由不同通道输入的,不同语言的各个层次的认知反应.实验结果表明,双侧前额皮层对高层语义加工,包括对篇章的归纳与抽象,具有特殊的功能,这种功能的神经学分布是对称的,这种功能及其对称性不随语言和输入通道的变化而变化.相比之下,前额皮层对读、听语言材料以及听音乐却显得不敏感.局部血流的变化只显示其对上述任务的一般性的注意力控制.     

Neural substrates of cognitive skill learning in Parkinson's disease

While cognitive skill learning is normally acquired implicitly through frontostriatal circuitry in healthy individuals, neuroimaging studies suggest that patients with Parkinson's disease (PD) do so by activating alternate, intact brain areas associated with explicit memory processing. To further test this hypothesis, 10 patients with PD and 12 healthy controls were tested on a modified, learning version of the Tower of London task while undergoing positron emission tomography at four different time points over the course of learning. Despite having less accurate problem solving abilities than controls, PD patients were able to acquire the skill learning task. However, as compared to controls, they maintained higher levels of cerebral blood flow activity in the dorsolateral prefrontal cortex and hippocampus and showed an increase in activity in the frontopolar cortex and posterior cingulate over the course of learning. These findings reflect a shift to the explicit memory system in PD patients, enabling them to learn this cognitive skill, which is normally acquired by control subjects using implicit learning strategies and frontostriatal circuitry.     

自我控制资源与认知资源相互影响的机制:整合模型

尽管有学者认为自我控制资源和认知资源应该是两种独立的资源,但近期的研究却表明两种资源是互相影响的.以往研究从执行控制的角度解释两种资源为什么相互影响,但却没有指出两种资源如何影响执行控制,以及缺乏考虑神经机制和自我控制资源调节变量在其中的作用.为更系统地解释两种资源相互影响的机制,作者提出了一个整合模型,该模型指出:(1)两种资源相互影响的主要原因是两者都受到执行控制和前额叶皮层的影响;(2)个体进行自我控制或认知加工会消耗能量,产生心理疲劳,降低执行任务的动机,表现为前额叶皮层激活水平下降;(3)前额叶皮层激活不足进一步限制了执行控制在随后的自我控制和认知加工任务中的作用,因而影响后续自我控制或认知加工任务的表现;(4)自我控制资源调节变量通过提高个体对疲劳的耐受性、补充能量和提高动机等方法,使前额叶皮层和执行控制在完成前一阶段任务后仍然能够正常发挥作用,从而维持个体在后续自我控制或认知加工任务上的表现.未来的研究可考察自我控制资源与其他认知加工的关系;用动态的认知神经研究方法,建立前额叶皮层激活水平在前后两阶段任务之间的中介作用模型,以及研究自我控制资源调节变量的神经机制.     

慢性应激损害大鼠学习记忆且抑制海马及额叶FGF2蛋白表达

慢性应激能够影响学习和记忆等认知功能。海马和额叶是与学习和记忆联系密切的脑区, 参与信息的获得、保持及提取。碱性成纤维生长因子(FGF2)对神经元发生、存活以及损伤修复具有重要促进作用, 目前成为神经系统退行性疾病相关研究的热点。本研究旨在探索慢性应激如何影响大鼠学习和记忆能力, 以及这一过程中FGF2蛋白在海马和额叶中表达的改变。实验中将16只雄性SD大鼠随机分为对照组和慢性应激组, 采用慢性不可预见温和刺激建立大鼠慢性应激模型, 通过Morris水迷宫实验及Y迷宫实验检测学习与记忆功能的改变, 并对海马及额叶中FGF2蛋白的表达情况进行Western blot及免疫组织化学检测。结果发现, 5周慢性应激导致大鼠学习和记忆能力受损, 海马及额叶FGF2蛋白表达下调。因此认为, FGF2蛋白可能参与慢性应激损害学习记忆能力的机制, 提示FGF2可能是诊断和治疗神经系统退行性病变的分子靶目标。     

The Cognitive Demands of Gait Retraining in Runners: An EEG Study

Abstract

High impact forces during running have been associated with tibial stress injuries. Previous research has demonstrated increasing step rate will decrease impact forces during running. However, no research has determined the cognitive demand of gait retraining. The primary purpose was to determine the cognitive demand and effectiveness of field-based gait retraining. We hypothesized that in-field gait retraining would alter running mechanics without increasing cognitive workload as measured by EEG following learning. Runners with a history of tibial injury completed a gait retraining protocol which included a baseline run, retraining phase, practice phase, and re-assessment following retraining protocol. Results demonstrated an increase in the theta, beta, and gamma power within prefrontal cortex during new learning and corresponding return to baseline following skill acquisition and changes across alpha, beta, gamma, mu, and theta in the motor cortex (p < .05). In the midline superior parietal cortex, spectral power was greater for theta activity during new learning with a corresponding alpha suppression. Overall, the results demonstrated the use of EEG as an effective tool to measure cognitive demand for implicit motor learning and the effectiveness of in-field gait retraining.