The effects of transcranial direct current stimulation (tDCS) on multitasking performance and oculometrics

Multitasking is the ability to perform more than one task simultaneously. The need to multitask is common in many industries especially within the military with tasks such as air traffic controllers, cyber defense operators and image analysts. However, as the time on task increases, information throughput can become overwhelming resulting in a performance decrement. Through task prioritizing, the operator is able to maintain performance on specific subtasks in which they selected as high importance while other subtasks experience a decrement. The objective of this study was to evaluate the effects of transcranial direct current stimulation (tDCS) applied to the left dorsolateral prefrontal cortex (ldLPFC) on information processing capabilities to improve individual and overall multitasking performance while performing the multi-attribute task battery (MATB). Two groups of 8 participants each received either 2 mA of anodal or sham tDCS while performing MATB. In addition, eye tracking was implemented to record eye movement patterns. In doing so, we were able to determine how much time the operator allocated to each of the subtasks within MATB and how their task priorities changed as workload demands increased. The findings provided evidence that 2 mA of anodal tDCS during MATB significantly improved overall information throughput compared to the sham group. With respect to the individual subtasks, communication and system monitoring displayed the greatest enhancement with anodal tDCS. Our data suggests that tDCS could be a useful tool to enhance information processing capabilities during a multitasking paradigm resulting in improved processing capabilities and information throughput.     

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。     

经颅电刺激与视功能调控

经颅电刺激(Transcranial Electrical Stimulation, TES)通过电极将特定模式的低强度电流作用于大脑头皮以调控皮层活动, 是一种非侵入、无创的神经刺激方法。根据刺激电流的模式的不同, TES分为经颅直流电刺激(tDCS), 经颅交流电刺激(tACS)和经颅随机电刺激(tRNS)。TES能对视功能诸如光幻视阈值、视野、对比敏感度、视知觉运动等进行一定程度上的调控, 并且能够与传统的视觉知觉学习训练相结合以调控视觉功能。对于不同的视觉功能, 不同的TES参数和模式的调控效果有所不同。     

Mind matters: A narrative review on affective state-dependency in non-invasive brain stimulation

Variability in findings related to non-invasive brain stimulation (NIBS) have increasingly been described as a result of differences in neurophysiological state. Additionally, there is some evidence suggesting that individual differences in psychological states may correlate with the magnitude and directionality of effects of NIBS on the neural and behavioural level. In this narrative review, it is proposed that the assessment of baseline affective states can quantify non-reductive properties which are not readily accessible to neuroscientific methods. Particularly, affective-related states are theorized to correlate with physiological, behavioural and phenomenological effects of NIBS. While further systematic research is needed, baseline psychological states are suggested to provide a complementary cost-effective source of information for understanding variability in NIBS outcomes. Implementing measures of psychological state may potentially contribute to increasing the sensitivity and specificity of results in experimental and clinical NIBS studies.     

Affective processing in positive schizotypy: Loose control of social-emotional information

Behavioral studies suggested heightened impact of emotionally laden perceptual input in schizophrenia spectrum disorders, in particular in patients with prominent positive symptoms. De-coupling of prefrontal and posterior cortices during stimulus processing, which is related to loosening of control of the prefrontal cortex over incoming affectively laden information, may underlie this abnormality. Pre-selected groups of individuals with low versus high positive schizotypy (lower and upper quartile of a large screening sample) were tested. During exposure to auditory displays of strong emotions (anger, sadness, cheerfulness), individuals with elevated levels of positive schizotypal symptoms showed lesser prefrontal–posterior coupling (EEG coherence) than their symptom-free counterparts (right hemisphere). This applied to negative emotions in particular and was most pronounced during confrontation with anger. The findings indicate a link between positive symptoms and a heightened impact particularly of threatening emotionally laden stimuli which might lead to exacerbation of positive symptoms and inappropriate behavior in interpersonal situations.     

Why is “blindsight” blind? A new perspective on primary visual cortex,recurrent activity and visual awareness

The neuropsychological phenomenon of blindsight has been taken to suggest that the primary visual cortex (V1) plays a unique role in visual awareness, and that extrastriate activation needs to be fed back to V1 in order for the content of that activation to be consciously perceived. The aim of this review is to evaluate this theoretical framework and to revisit its key tenets. Firstly, is blindsight truly a dissociation of awareness and visual detection? Secondly, is there sufficient evidence to rule out the possibility that the loss of awareness resulting from a V1 lesion simply reflects reduced extrastriate responsiveness, rather than a unique role of V1 in conscious experience? Evaluation of these arguments and the empirical evidence leads to the conclusion that the loss of phenomenal awareness in blindsight may not be due to feedback activity in V1 being the hallmark awareness. On the basis of existing literature, an alternative explanation of blindsight is proposed. In this view, visual awareness is a “global” cognitive function as its hallmark is the availability of information to a large number of perceptual and cognitive systems; this requires inter-areal long-range synchronous oscillatory activity. For these oscillations to arise, a specific temporal profile of neuronal activity is required, which is established through recurrent feedback activity involving V1 and the extrastriate cortex. When V1 is lesioned, the loss of recurrent activity prevents inter-areal networks on the basis of oscillatory activity. However, as limited amount of input can reach extrastriate cortex and some extrastriate neuronal selectivity is preserved, computations involving comparison of neural firing rates within a cortical area remain possible. This enables “local” read-out from specific brain regions, allowing for the detection and discrimination of basic visual attributes. Thus blindsight is blind due to lack of “global” long-range synchrony, and it functions via “local” neural readout from extrastriate areas.     

Family play,reading, and other stimulation and early childhood development in five low-and-middle-income countries

This paper used longitudinal data from five studies conducted in Bangladesh, Bhutan, Cambodia, Ethiopia, and Rwanda to examine the links between family stimulation and early childhood development outcomes (N = 4904; M_age = 51.5; 49% girls). Results from random-effects and more conservative child-fixed effects models indicate that across these studies, family stimulation, measured by caregivers’ engagement in nine activities (e.g., reading, playing, singing), predicted increments in children's early numeracy, literacy, social-emotional, motor, and executive function skills (standardized associations ranged from 0.05 to 0.11 SD). Study-specific models showed variability in the estimates, with null associations in two out of the five studies. These findings indicate the need for additional research on culturally specific ways in which caregivers may support early development and highlight the importance of promoting family stimulation to catalyze positive developmental trajectories in global contexts.

Research Highlights

• Research on the links between family stimulation and early childhood development in low-and-middle-income countries (LMICs) is limited.
• We used longitudinal data from studies conducted in five LMICs to examine the links between family stimulation and early childhood development outcomes.
• Results suggest that family stimulation predicted increments in children's numeracy, literacy, social-emotional, motor, and executive function skills.
• We found variability in the observed estimates, with null associations in two out of the five studies, suggesting the need for additional research in LMICs.

     

Self processing in the brain: A paradigmatic fMRI case study with a professional singer

Understanding the mechanisms involved in perception and conception of oneself is a fundamental psychological topic with high relevance for psychiatric and neurological issues, and it is one of the great challenges in neuroscientific research. The paradigmatic single-case study presented here aimed to investigate different components of self- and other-processes and to elucidate corresponding neurobiological underpinnings. An eminent professional opera singer with profound performance experience has undergone functional magnetic resonance imaging and was exposed to excerpts of Mozart arias, sung by herself or another singer. The results indicate a distinction between self- and other conditions in cortical midline structures, differentially involved in self-related and self-referential processing. This lends further support to the assumption of cortical midline structures being involved in the neural processing of self-specific stimuli and also confirms the power of single case studies as a research tool.