Cognition and affective style: Individual differences in brain electrical activity during spatial and verbal tasks

Relations between brain electrical activity and performance on two cognitive tasks were examined in a normal population selected to be high on self-reported measures of Positive or Negative Affectivity. Twenty-five right-handed women, from an original pool of 308 college undergraduates, were the participants. EEG was recorded during baseline and during psychometrically matched spatial and verbal tasks. As predicted, participants who were high in Positive Affectivity performed equally well on the verbal and spatial tasks, while participants who were high in Negative Affectivity had spatial scores that were lower than their verbal scores. There were no group differences in baseline EEG. Both groups exhibited left central activation (i.e., alpha suppression) during the verbal and spatial tasks. When EEG data were analyzed separately for the group high in Positive Affectivity, there was evidence of parietal activation for the spatial task relative to the verbal task. The EEG data for the group high in Negative Affectivity had comparable EEG power values during verbal and spatial tasks at parietal scalp locations. These data suggest that, within a selected normal population, differences in affective style may interact with cognitive performance and with the brain electrical activity associated with that performance.     

Comparison of magneto-and electroencephalographic techniques in event-related response research—a brief survey

Event-related brain potentials are widely used in psychophysiological and neurophysiological research. Recently it has become possible to record weak magnetic fields associated with the electric events of the human brain. In this short survey the magnetoencephalo-graphic (MEG) techniques are compared with the conventional electric measures. MEG and EEG are sensitive to current sources of different orientation. Extracerebral tissues smear and damp the electric potentials but they do not have any significant effect on the magnetic fields. EEG measures potential differences whereas the actual current paths determine the magnetic fields measured outside the skull. In general MEG provides better spatial resolution than the electric recordings, as far as the cortical sources are concerned. It is concluded that EEG and MEG are complementary noninvasive techniques in brain research. As an example slow EEG and MEG shifts preceding voluntary foot movements are compared.     

Non-invasive estimation of local field potentials for neuroprosthesis control

Recent experiments have shown the possibility of using the brain electrical activity to directly control the movement of robots or prosthetic devices in real time. Such neuroprostheses can be invasive or non-invasive, depending on how the brain signals are recorded. In principle, invasive approaches will provide a more natural and flexible control of neuroprostheses, but their use in humans is debatable given the inherent medical risks. Non-invasive approaches mainly use scalp electroencephalogram (EEG) signals and their main disadvantage is that these signals represent the noisy spatiotemporal overlapping of activity arising from very diverse brain regions, i.e., a single scalp electrode picks up and mixes the temporal activity of myriads of neurons at very different brain areas. In order to combine the benefits of both approaches, we propose to rely on the non-invasive estimation of local field potentials (LFP) in the whole human brain from the scalp measured EEG data using a recently developed inverse solution (ELECTRA) to the EEG inverse problem. The goal of a linear inverse procedure is to de-convolve or un-mix the scalp signals attributing to each brain area its own temporal activity. To illustrate the advantage of this approach we compare, using an identical set of spectral features, classification of rapid voluntary finger self-tapping with left and right hands based on scalp EEG and non-invasively estimated LFP on two subjects using a different number of electrodes.

Relations between infants’ emerging reach‐grasp competence and event‐related desynchronization in EEG

Recent reports of similar patterns of brain electrical activity (electroencephalogram: EEG) during action execution and observation, recorded from scalp locations over motor‐related regions in infants and adults, have raised the possibility that two foundational abilities – controlling one's own intentional actions and perceiving others’ actions – may be integrally related during ontogeny. However, to our knowledge, there are no published reports of the relations between developments in motor skill (i.e. recording actual motor skill performance) and EEG during both action execution and action observation. In the present study we collected EEG from 21 9‐month‐olds who were given opportunities to reach for toys and who also observed an experimenter reach for toys. Event‐related desynchronization (ERD) was computed from the EEG during the reaching events. We assessed infants’ reaching‐grasping competence, including reach latency, errors, preshaping of the hand, and bimanual reaches, and found that desynchronization recorded in scalp electrodes over motor‐related regions during action observation was associated with action competence during execution. Infants who were more competent reachers, compared to less competent reachers, exhibited greater ERD while observing reaching‐grasping. These results provide initial evidence for an early emerging neural system integrating one's own actions with the perception of others’ actions.     

Magnetic source images of human brain functions

The advent of large arrays of superconducting magnetic field sensors makes it possible to properly sample the topography of the magnetic field pattern across the human scalp with a temporal resolution of a few milliseconds. These capabilities can be exploited for computing a best estimate of the spatiotemporal evolution of electrical currents within coherently active neural populations distributed across the cerebral cortex. Data from 200 sensors can be interpreted by the method of singular value decomposition to compute a best estimate for the strengths of more than 9,000 current elements that define the magnetic source image moment by moment. Recently, an extension of this technique has been developed to characterize the cortical sources of alpha rhythm. This holds promise for providing a means of identifying the cortical regions that participate in cognitive functions such as mental imagery.     

感知音乐音质的EEG探究

欣赏音乐是一种审美的体验活动,不同的音质会使人产生不同的感受。为探究音乐和EEG的关系,本文选用音乐《黑人舞曲》,运用主成分分析等方法,研究了11位在校大学生在欣赏不同音质音乐时的EEG特征。结果发现:在欣赏不同音质音乐时大脑皮层右颞等处快波功率差异显著。大脑对音乐的精细加工与大脑右颞等区的电活动密切相关。     

Longitudinal study of perception of structured optic flow and random visual motion in infants using high‐density EEG

Electroencephalogram (EEG) was used in infants at 3–4 months and 11–12 months to longitudinally study brain electrical activity as the infants were exposed to structured forwards and reversed optic flow, and non‐structured random visual motion. Analyses of visual evoked potential (VEP) and temporal spectral evolution (TSE, time‐dependent amplitude changes) were performed on EEG data recorded with a 128‐channel sensor array. VEP results showed infants to significantly differentiate between the radial motion conditions, but only at 11–12 months where they showed shortest latency for forwards optic flow and longest latency for random visual motion. When the TSE results of the motion conditions were compared with those of a static non‐flow dot pattern, infants at 3–4 and 11–12 months both showed significant differences in induced activity. A decrease in amplitudes at 5–7 Hz was observed as desynchronized theta‐band activity at both 3–4 and 11–12 months, while an increase in amplitudes at 9–13 Hz was observed as synchronized alpha‐band activity only at 11–12 months. It was concluded that brain electrical activities related to visual motion perception change during the first year of life, and these changes can be observed both in the VEP and induced activities of EEG. With adequate neurobiological development and locomotor experience infants around 1 year of age rely, more so than when they were younger, on structured optic flow and show a more adult‐like specialization for motion where faster oscillating cell assemblies have fewer but more specialized neurons, resulting in improved visual motion perception.     

Integrating electrophysiology and neuroimaging in the study of human cognition

Noninvasive recordings of electrical and magnetic fields generated by neuronal activity have helped to characterize the temporal sequencing and mechanisms underlying human cognition. Progress is being made toward the goal of localizing the intracranial loci at which many important electromagnetic signals are generated through the use of new analytic techniques and of scalp recordings of electromagnetic activity in neurological patients and through related work in animals. Such methods alone, however, do not yet have the three-dimensional spatial resolution that is necessary in order to identify the intracranial anatomical structures that are involved in the generation of externally recorded activity and, thus, cannot yet inform us with precision about the anatomical substrates of neural events. In comparison, neuroimaging methods, such as positron emission tomography and functional magnetic resonance imaging, can provide higher spatial resolution information about which brain structures are involved in perceptual, motor, and cognitive processes. However, these imaging methods do not yield much information about the time course of brain activity. One promising approach is to combine electromagnetic recordings and functional neuroimaging in order to gain knowledge about the spatiotemporal organization of human cognition. Here we review how electrophysiology and functional neuroimaging can be combined in the study of attention in normal humans.     

利用时频分析研究非相位锁定脑电活动

时频分析技术自20世纪80年代被引入到心理学脑电数据分析领域以来, 克服了传统的时域ERP方法只能分析相位锁定成分的缺陷, 可以帮助研究者挖掘到脑电信号中非相位锁定的成分。在心理学领域, 应用最多的时频分析方法是小波变换和Hilbert变换, 而能量、相位一致性和耦合是三个最常用的分析指标。研究者利用不同的分析指标来揭示不同的心智过程。不同频段的能量被认为体现了不同的认知过程, 如α能量被发现与注意选择性有关, 而γ能量则与特征整合相关。相位一致性常被用于讨论ERP产生的机制。耦合则通常说明了长距离脑区之间的信息交流以及高级脑区对低级脑区的认知控制, 在完成各种复杂认知任务的时候会表现出不同的耦合模式。     

Thoughts on the Meaning of Brain Electrical Activity

Recordings of electrical brain activity have provided a rich field of data. These data are harvested at at least two scales of inquiry: scalp recordings from humans have accessed cognitive aspects of the mind/brain relationship, and microelectrode recordings in animals have delineated circuits involved in sensory and motor processes. As yet, there are few studies that have attempted to reconcile the findings obtained at these different scales. It is such reconciliation that we are attempting in experiments performed in our Center for Brain Research and Informational Sciences. A progress report follows.     

Differences in brain information transmission between gifted and normal children during scientific hypothesis generation

The purpose of the present study was to investigate differences in neural information transmission between gifted and normal children involved in scientific hypothesis generation. To investigate changes in the amount of information transmission, the children’s averaged-cross mutual information (A-CMI) of EEGs was estimated during their generation of scientific hypotheses. We recorded EEG from 25 gifted and 25 age-matched normal children using 16 electrodes on each subject’s scalp. To generate hypotheses, the children were asked to observe 20 “quail eggs” that gave rise to questions. After observation, they were asked to generate a scientific hypothesis—a tentative causal explanation for the questions evoked. The results of this study revealed several distinguishing brain activities between gifted and normal children during hypothesis generation. In contrast to normal children, gifted children showed increased A-CMI values between the left temporal and central, between the left temporal and parietal, and between the left central and parietal locations while generating a hypothesis. These results suggested that gifted children more efficiently distribute the cognitive resources essential to cope with hypothesis generation.     

Temporal dynamics of awareness for facial identity revealed with ERP

In this study, we investigated the scalp recorded event-related potential (ERP) responses related to visual awareness. A backward masking procedure was performed while high-density EEG recordings were carried out. Subjects were asked to detect a familiar face, presented at durations that varied parametrically between 16 and 266 ms. ERPs were computed and awareness was assessed using a sensitivity measure from signal detection theory (d'). Modifications in the electrical scalp topographies were found to reflect visual awareness of the stimulus. In particular, an early map topography was found to emerge progressively around 230 ms, showing a pattern of increase similar to the measure of visual awareness. This was followed by an increase in duration of a second, P300-like map. Source localisation for the early awareness-related topography revealed the activation of a distributed network of brain areas including frontal and temporo-occipital regions. Our results suggest that conscious experience emerges in parallel with the activation of a specific neural network that occurs in a time window beginning from about 200 ms.     

Whispering gallery mode sensor for phase transformation and solidification studies

Whispering gallery mode (WGM) sensors are created by coupling a dielectric microresonator with the evanescent field of an optical fiber. Since the sensor is created by two separate entities, most of the existing studies are limited to using them in fluid environments, such as air or water, for the ease of manipulation and placement in the optimum configuration. This work is focused on studying the possibility of using WGM sensors inside a solid material. The sensor is immersed in water, which is cooled to solid state and the sensor survival is monitored. In subsequent studies, three remelting cycles are carried out and temperature measurements are obtained through the sensor. The sensor output is calibrated with the temperature data obtained from a thermocouple. The results show that a linear relationship exists between temperature and WGM shift, which enables application of these sensors in temperature measurement. Considering that the sensitivity of WGM sensors is very high (10^?6 N force and 10^?5 K temperature), they can be used for high resolution studies on solidification in cryogenic environments.     

Magnetoencephalography in pediatric neuroimaging

Neural currents give rise to electroencephalogram (EEG) and magnetoencephalogram (MEG). MEG has selective sensitivity to tangential currents (from fissural cortex), and less distorted signals compared with EEG. A major goal of MEG is to determine the location and timing of cortical generators for event‐related responses, spontaneous brain oscillations or epileptiform activity. MEG provides a spatial accuracy of a few mm under optimal conditions, combined with an excellent submillisecond temporal resolution, which together enable spatiotemporal tracking of distributed neural activities, e.g. during cognitive tasks or epileptic discharges. While the present focus of pediatric MEG is on tailored epilepsy surgery, the complete noninvasiveness of MEG also provides unlimited possibilities to study the brain functions of healthy and developmentally deviant children.     

大脑电刺激在听觉语言加工研究中的应用

大脑电刺激是历史悠久但近年来才广泛应用在人类被试上的实验技术。通过对颅内刺激位点进行电刺激, 并分析引发的暂时性行为功能变化和记录位点的电位活动, 大脑电刺激技术可以揭示认知加工过程中脑区内的功能作用与脑区间的有效连接。通过对听觉语言加工过程相关的丘脑、听觉皮层、高级语言皮层进行电刺激, 现有研究发现了各个脑区的不同功能特点以及不同脑区间的信息传递机制, 为进一步探索听觉语言加工的神经机制提供了新的视角。     

Event-related potential (ERP) evidence for the differential cognitive processing of semantic jokes and pun jokes

Brain-imaging studies report that separate neural correlates are associated with processing of different types of humorous materials. However, such evidence lacks temporal information. In this study, we examined the temporal dynamics of humour comprehension between two types of jokes: semantic (SEMs) and pun (PUNs) jokes, using electroencephalographic (EEG) techniques. Thirty SEMs and 30 PUNs were presented to 16 healthy subjects, and their EEG data were concurrently recorded. PUNs consequently showed a larger N400 amplitude than did SEMs, without a specified scalp site, which implies that PUNs induce greater surprise and semantic violation. Meanwhile, SEMs induced a larger P600-like amplitude at the posterior site, which implies that, in order to understand SEMs, higher working memory loads are needed to form novel associations and successfully frame-shift. A possible explanation is the differing logical mechanisms used to understand SEMs and PUNs: the former builds on semantic relationships, the latter on phonological causality.     

Wearable strain sensor suit for infants to measure limb movements under interaction with caregiver

Development of motion capture technology has enabled the measurement of body movements over long periods of time in daily life. Although accelerometers have been used as primary sensors, problems arise when they are used to measure the movements of infants. Because infants and caregivers interact frequently, accelerometer data from infants may be significantly distorted by a caregiver’s movement. To overcome this problem, a strain sensor suit was developed for infants to measure flexion and extension movements of the limbs. A case study was performed to analyze the strain sensor data of an infant in relation to the accelerometer data of the infant’s and a caregiver’s body under various types of infant–caregiver interaction. The results demonstrated that the strain sensor data had low correlation with the accelerometer data of the infant and caregiver while the accelerometer data between infant and caregiver had higher correlation. This suggests that the strain sensor is suitable to detect limbs’ angular displacements mostly independent from the translational body movements exerted by a caregiver.     

Self‐focused cognitive emotion regulation style as associated with widespread diminished EEG fractal dimension

The cognitive regulation of emotions is important for human adaptation. Self‐focused emotion regulation (ER) strategies have been linked to the development and persistence of anxiety and depression. A vast array of research has provided valuable knowledge about the neural correlates of the use of specific self‐focused ER strategies; however, the resting neural correlates of cognitive ER styles, which reflect an individual's disposition to engage in different forms of ER in order to manage distress, are largely unknown. In this study, associations between theoretically negative ER style (self‐focused or not) and the complexity (fractal dimension, FD) of the resting EEG at frontal, central, parietal, and occipital regions were investigated in 58 healthy volunteers. The Cognitive Emotion Regulation Questionnaire was used as the self‐report measure of ER style. Results showed that a diminished FD over the scalp significantly correlated with self‐focused ER style scores, even after controlling for negative affect, which has been also considered to influence the use of ER strategies. The lower the EEG FD, the higher were the self‐focused ER style scores. Correlational analyses of specific self‐focused ER strategies showed that self‐blaming and rumination were negatively associated with diminished FD of the EEG, but catastrophizing and blaming others were not. No significant correlations were found for ER strategies more focused on situation or others. Results are discussed within the self‐organized criticality theory of brain dynamics: The diminished FD of the EEG may reflect a disposition to engage in self‐focused ER strategies as people prone to ruminate and self‐blame show a less complex resting EEG activity, which may make it more difficult for them to exit their negative emotional state.