Inter-and intra-hemispheric EEG coherence in patients with mild cognitive impairment at rest and during working memory task

Objective： To assess functional relationship by calculating inter- and intra-hemispheric electroencephalography （EEG） coherence at rest and during a working memory task of patients with mild cognitive impairment （MCI）. Methods： The sample consisted of 69 subjects： 35 patients （n = 17 males, n = 18 females; 52-71 years old） and 34 normal controls （n = 17 males, n = 17 females; 51 -63 years old）. Mini-mental state examination （MMSE） of two groups revealed that the scores of MCI patients did not differ significantly from those of normal controls （P〉0.05）. In EEG recording, subjects were performed at rest and during working memory task. EEG signals from F3-F4, C3-C4, P3-P4, T5-T6 and O1-O2 electrode pairs are resulted from the inter-hemispheric action, and EEG signals from F3-C3, F4-C4, C3-P3, C4-P4, P3-O1, P4-O2, T5-C3, T6-C4, T5-P3 and T6-P4 electrode pairs are resulted from the intra-hemispheric action for delta （1.0-3.5 Hz）, theta （4.0-7.5 Hz）, alpha-1 （8.0-10.0 Hz）, alpha-2 （10.5-13.0 Hz）, beta-1 （13.5-18.0 Hz） and beta-2 （18.5-30.0 Hz） frequency bands. The influence of inter- and intra-hemispheric coherence on EEG activity with eyes closed was examined using fast Fourier transformation from the 16 sampled channels. Results： During working memory tasks, the inter- and intra-hemispheric EEG coherences in all bands were significantly higher in the MCI group in comparison with those in the control group （P〈0.05）. However, there was no significant difference in inter- and intra-hemispheric EEG coherences between two groups at rest. Conclusion： Experimental results comprise evidence that MCI patients have higher degree of functional connectivity between hemispheres and in hemispheres during working condition, It suggests that MCI may be associated with compensatory processes during working memory tasks between hemispheres and in hemispheres. Moreover, failure of normal cortical connections may exist in MCI patients.     

Abnormal cortical functional connections in Alzheimer＇s disease： analysis of inter- and intra-hemispheric EEG coherence

To investigate inter- and intra-hemispheric electroencephalography (EEG) coherence at rest and during photic stimulation of patients with Alzheimer‘s disease (AD). Thirty-five patients (12 males, 23 females; 52-64 y) and 33 sex- and age-matched controls (12 males, 21 females; 56-65 y) were recruited in the present study. EEG signals from C3-C4, P3-P4, TS-T6 and O1-O2 electrode pairs resulted from the inter-hemispheric action, and EEG signals from C3-P3, C4-P4, P3-O1, P4-O2, C3-O1, C4-O2, TS-O1 and T6-O2 electrode pairs resulted from the intra-hemispheric action. The influence of inter- and intra-hemispheric coherence on EEG activity with eyes closed was examined, using fast Fourier transformation from the 16 sampled channels. The frequencies of photic stimulation were fixed at 5, l0 and 15 Hz, respectively. The general decrease of AD patients in inter- and intra-hemispheric EEG coherence was more significant than that of the normal controls at the resting EEG, with most striking decrease observed in the alpha-1 (8.0-9.0 Hz) and alpha-2 (9.5-12.5 Hz) bands. During photic stimulation, inter- and intra-hemispheric EEG coherences of the AD patients having lower values in the alpha (9.5-10.5 Hz) band than those of the control group. It suggests that under stimulated and non-stimulated conditions, AD patients had impaired inter- and intra-hemispheric functional connections, indicating failure of brain activation in alpha-related frequency.     

Study on EEG power and coherence in patients with mild cognitive impairment during working memory task

To investigate the features of electroencephalography (EEG) power and coherence at rest and during a working memory task of patients with mild cognitive impairment (MCI). Thirty-five patients (17 males, 18 females; 52～71 years old) and 34 sex- and age-matched controls (17 males, 17 females; 51～63 years old) were recruited in the present study. Mini-Mental State Examination (MMSE) of 35 patients with MCI and 34 normal controls revealed that the scores of MCI patients did not differ significantly from those of normal controls (P＞0.05). Then, EEGs at rest and during working memory task with three levels of working memory load were recorded. The EEG power was computed over 10 channels: right and left frontal (F3, F4), central (C3,C4), parietal (P3, P4), temporal (TS, T6) and occipital (O1, O2); inter-hemispheric coherences were computed from five electrode pairs of F3-F4, C3-C4, P3-P4, T5-T6 and O1-O2 for delta (1.0～3.5 Hz), theta (4.0～7.5 Hz), alpha-1 (8.0～10.0 Hz), alpha-2 (10.5～13.0 Hz), beta-1 (13.5～18.0 Hz) and beta-2 (18.5～30.0 Hz) frequency bands. All values of the EEG power of MCI patients were found to be higher than those of normal controls at rest and during working memory tasks. Furthermore, the values of EEG power in the theta, alpha-1, alpha-2 and beta-1 bands of patients with MCI were significantly high (P＜0.05) in comparison with those of normal controls. Correlation analysis indicated a significant negative correlation between the EEG powers and MMSE scores. In addition, during working memory tasks, the EEG coherences in all bands were significantly higher in the MCI group in comparison with those in the control group (P＜0.05). However, there was no significant difference in EEG coherences between two groups at rest. These findings comprise evidence that MCI patients have higher EEG power at rest, and higher EEG power and coherence during working conditions. It suggests that MCI may be associated with compensatory processes at rest and during working memory tasks. Moreover, failure of normal cortical connections may be exist in MCI patients.     

A psychobiological perspective on working memory performance at 8 months of age

Fifty 8-month-old infants participated in a study of the interrelations among cognition, temperament, and electrophysiology. Better performance on a working memory task (assessed using a looking version of the A-not-B task) was associated with increases in frontal-parietal EEG coherence from baseline to task, as well as elevated levels of frontal-occipital coherence during both baseline and task. Enhanced performance was also associated with decreased heart period (increased heart rate) from baseline to task. Infants with better working memory performance had parents who rated them high on activity level and distress to limitations. When considered collectively, EEG coherence and heart period contributed unique variance in the prediction of high and low performance groups. Implications for the study of infant cognition are discussed.     

The Relations Between Children’s Reading Comprehension, Working Memory, Language Skills and Components of Reading Decoding in a Normal Sample

The primary aim of the current study was to identify the strongest independent predictors of reading comprehension using word reading, language and memory variables in a normal sample of 180 children in grades 3–5, with a range of word reading skills. It was hypothesized that orthographic processing, receptive vocabulary and verbal working memory would all make independent contributions to reading comprehension. The contributions of reading speed, receptive grammatical skills, exposure to print, visuospatial working memory and verbal learning and retrieval (a measure of longer-term retention) were also investigated. Working memory tasks that required the processing and storage of numerical and spatial material were used. One of the numerical working memory tasks was based on the number span task developed by Yuill, Oakhill, and Parkin British Journal of Psychology, 1989, 80, 351–361. A visuospatial equivalent of that task was developed from the forward Corsi block task [Corsi, Abstracts International, 1973, 34, 891]. The results revealed that, after controlling for age and general intellectual ability, the word reading and the language variables had a much stronger relation with reading comprehension than the memory variables. The strongest independent predictor of reading comprehension was orthographic processing since it captured variance in both word reading, language skills and verbal working memory. The forward Corsi task and performance on a measure of verbal learning and retrieval each made small independent contributions to reading comprehension but the contribution of verbal working memory was not significant. It was concluded that tasks measuring the interplay between short-term and long-term memory, in which new information is combined with information already stored in long-term memory, may better predict reading comprehension measured with the text available than working memory tasks which only have a short-term memory component.     

Neural Oscillation Reveals Deficits in Visuospatial Working Memory in Children With Developmental Coordination Disorder

The electroencephalographic (EEG) oscillations associated with visuospatial working memory (VSWM) were examined in children with developmental coordination disorder (DCD; 10–11 years; N = 29) and typically developing (TD) children (10–11 years; N = 29). Behaviorally, DCD showed poorer VSWM than TD, which coincided with the diminished ability of DCD in modulating neural oscillations. Furthermore, prestimulus oscillatory alpha activity was correlated with VSWM performance. The results suggest that children with DCD might have a reduced ability to encode and recognize new information, and in particular have difficulty in maintaining task‐relevant information, resulting in poorer VSWM. This study thus concludes that changes in oscillatory EEG activity reflect some of the problems leading to cognitive deficits in DCD.     

Time-frequency analysis of EEG signals evoked by voluntary,stimulated and imaginary motions

In order to investigate the characteristics of sensorimotor cortex during motor execution(ME), voluntary, stimulated and imaginary finger flexions were performed by ten volunteer subjects. Electroencephalogram(EEG) data were recorded according to the modified 10-20 International EEG System. The patterns were compared by the analysis of the motion-evoked EEG signals focusing on the contralateral(C3) and ipsilateral(C4) channels for hemispheric differences. The EEG energy distributions at alpha(8—13 Hz), beta(14—30 Hz) and gamma(30—50 Hz) bands were computed by wavelet transform(WT) and compared by the analysis of variance(ANOVA). The timefrequency(TF) analysis indicated that there existed a contralateral dominance of alpha post-movement event-related synchronization(ERS) pattern during the voluntary task, and that the energy of alpha band increased in the ipsilateral area during the stimulated(median nerve of wrist) task. Besides, the contralateral alpha and beta event-related desynchronization(ERD) patterns were observed in both stimulated and imaginary tasks. Another significant difference was found in the mean power values of gamma band(p0.01)between the imaginary and other tasks. The results show that significant hemispheric differences such as alpha and beta band EEG energy distributions and TF changing phenomena(ERS/ERD) were found between C3 and C4 areas during all of the three patterns. The largest energy distribution was always at the alpha band for each task.     

轻度认知障碍患者早期面孔加工N170的研究

目的研究轻度认知障碍患者面孔早期加工的脑机制。方法被试者分为正常老年对照（NC）组和轻度认知障碍（MCI）组,各16名,均为右利手。刺激包括3种卡通面孔（中性、微笑、愤怒）和3种非面孔,要求被试者进行面孔识别任务,同时记录32导脑电。结果①MCI组及NC组均产生了明显的颞-枕区分布的面孔特异性成分N170;②与NC组相比,MCI组N170潜伏期显著延长、波幅降低。结论MCI患者在面孔表情早期加工阶段即出现异常。     

Long‐Term Episodic Memory in Children with Attention‐Deficit/Hyperactivity Disorder

Twenty‐nine grade‐matched 4th–8th‐grade males, 12 with attention‐deficit/hyperactivity disorder (ADHD) (age M= 12.2 years, SD= 1.48), and 17 without (age M= 11.5, SD= 1.59), completed two working memory tasks (digit span and the Simon game) and three long‐term episodic memory tasks (a personal event memory task, story memory task, and picture recognition task). In line with clinical observations, children with ADHD performed worse than peers on all working memory tasks, but performed as well as or better than peers on long‐term episodic tasks, demonstrating particularly detailed memory for personally experienced past events. Participants' parents also completed questionnaires about their children's memories in daily life. Parents rated children with ADHD lower than children without ADHD on working and semantic memory (e.g., remembering names, spelling, and math), but rated them as high or higher on memory for events. Implications for theory and educational practice are discussed.     

The neural correlates of working memory training in typically developing children

Working memory training improves children's cognitive performance on untrained tasks; however, little is known about the underlying neural mechanisms. This was investigated in 32 typically developing children aged 10–14 years (19 girls and 13 boys) using a randomized controlled design and multi-modal magnetic resonance imaging (Devon, UK; 2015–2016). Training improved working memory performance and increased intrinsic functional connectivity between the bilateral intraparietal sulci. Furthermore, improvements in working memory were associated with greater recruitment of the left middle frontal gyrus on a complex span task. Repeated engagement of fronto-parietal regions during training may increase their activity and functional connectivity over time, affording greater working memory performance. The plausibility of generalizable cognitive benefits from a neurobiological perspective and implications for neurodevelopmental theory are discussed.     

Working memory and mathematics: A review of developmental,individual difference,and cognitive approaches

Working memory refers to a mental workspace, involved in controlling, regulating, and actively maintaining relevant information to accomplish complex cognitive tasks (e.g. mathematical processing). Despite the potential relevance of a relation between working memory and math for understanding developmental and individual differences in mathematical skills, the nature of this relationship is not well-understood. This paper reviews four approaches that address the relation of working memory and math: 1) dual task studies establishing the role of working memory during on-line math performance; 2) individual difference studies examining working memory in children with math difficulties; 3) studies of working memory as a predictor of mathematical outcomes; and 4) longitudinal studies of working memory and math. The goal of this review is to evaluate current information on the nature of the relationship between working memory and math provided by these four approaches, and to present some of the outstanding questions for future research.     

Mixture growth models of RAN and RAS row by row: insight into the reading system at work over time

Children (n = 122) and adults (n = 200) with dyslexia completed rapid automatic naming (RAN) letters, rapid automatic switching (RAS) letters and numbers, executive function (inhibition, verbal fluency), and phonological working memory tasks. Typically developing 3rd (n = 117) and 5th (n = 103) graders completed the RAS task. Instead of analyzing RAN/RAS results the usual way (total time), growth mixture modeling assessed trajectories of successive times for naming 10 symbols in each of five rows. For all three samples and both RAN and RAS, two latent classes were identified. The “faster” class performed slowly on the first row and increased time by small increments on subsequent rows. The “slower” latent class performed more slowly on the first row, and children, but not adults, increased time by larger increments on subsequent rows. For children, both the initial row (automaticity index) and slope (sustained controlled processing index) of the trajectory differentiated the classes. For adults, only the initial row separated the classes. The longest time was on row 3 for RAN and row 4 for RAS. For the typically developing 5th graders, close in age to the children with dyslexia, the trajectories were flatter than for children with dyslexia and only the slower class (4%) showed the peak on row 4. For children with dyslexia, inhibition predicted RAN slope within the slower latent class and phonological working memory predicted RAS slope for both latent classes. For adults with dyslexia, inhibition and phonological working memory differentiated both latent classes on RAN intercept and RAS slope. Taken together, RAN, which may assess the phonological loop of working memory, and RAS, which may assess the central executive in working memory, may explain the timing deficit in dyslexia in sustaining coordinated orthographic-phonological processing over time. This research was supported by Grant Ns. P50 33812 and R01 HD25858 from the National Institute of Child Health and Human Development, Virginia W. Berninger, PI.     

Individual differences in spatial text processing: High spatial ability can compensate for spatial working memory interference

The present study investigates the relation between spatial ability and visuo-spatial and verbal working memory in spatial text processing. In two experiments, participants listened to a spatial text (Experiments 1 and 2) and a non-spatial text (Experiment 1), at the same time performing a spatial or a verbal concurrent task, or no secondary task. To understand how individuals who differ in spatial ability process spatial text during dual task performance, spatial individual differences were analyzed. The tasks administered were the Vandenberg and Kuse [Vandenberg, S. G., & Kuse, A. R. (1978). Mental rotation, a group test of three-dimensional spatial visualization. Perceptual and Motor Skills, 47, 599-604.] mental rotation test (MRT) and a reading comprehension task (RCT). Individuals with high (HMR) and low (LMR) mental rotation differed in MRT scores but had similar RCT performance. Results showed that the HMR group, in contrast with LMR counterparts, preserved good spatial text recall even when a spatial concurrent task was performed; however, Experiment 2 revealed a modification of spatial concurrent task performance in LMR as well in HMR group. Overall, results suggest that HMR individuals have more spatial resources than LMR individuals, allowing them to compensate for spatial working memory interference, but only to a limited extent, given that the processing of spatial information is still mediated by VSWM.     

Writing difficulties in Alzheimer’s disease and mild cognitive impairment

The present study addresses the scope of the writing difficulties observed in patients with Alzheimer’s disease (AD) and mild cognitive impairment (MCI). Patients with AD, patients with MCI and healthy controls performed a written picture-naming task and a direct copy transcoding task in which phonology-to-orthography (P–O) consistency was manipulated. Written latencies, inter-letter durations, mean word pen pressure and number of errors were measured. Results revealed that there was a significant difference between the control group and both groups of patients in written latencies and number of errors. However, in inter-letter interval or mean pen pressure there were significant differences only between the group with AD and the other groups. P–O consistency and the type of task produced similar effects in the three groups of participants, suggesting a general deficit affecting the ability to access/generate orthographic representations. The relevance of these results for understanding the spelling impairment in AD and MCI are discussed.

     

Role of working memory in explaining the performance of individuals with specific reading comprehension difficulties: A meta-analysis

It is well established that working memory is related to reading comprehension ability. However, its role in explaining specific reading comprehension difficulties is still under debate: the issue mainly concerns whether the contribution of working memory is dependent on task modality (verbal tasks being more predictive than visuo-spatial tasks) and/or on the attentional control implied in working memory tasks (tasks requiring storage/manipulation being more predictive than storage-only tasks, regardless of task modality). Meta-analysis is used here to examine the relevance of several working memory measures in distinguishing between the performance of poor and good comprehenders in relation to the modality of the working memory task, and the involvement of controlled attention required by such a task. Our results demonstrate that memory tasks that are demanding in terms of attentional control and that require verbal information processing are best at distinguishing between poor and good comprehenders, suggesting that both domain-specific factors as well as general factors of working memory contribute to reading comprehension performance. The implications for different models of working memory in relation to reading comprehension are discussed.     

Cognitive Style and Individual Differences in EEG Alpha During Information Processing

Abstract When presented with a task, it was hypothesised that different people tend to process the same information in different ways, using different areas of the brain, depending upon their cognitive style. The study used 15 adult subjects, who received the computer‐presented Cognitive Styles Analysis to assess their positions on two basic cognitive style dimensions: the Wholist‐Analytic and Verbal‐Imagery. In a computer‐presented task, subjects were asked to view words presented singly at a rate of two, five and 10 words/second and in pairs at five and 10 word‐pairs/second and to press a key when a word appeared which was in a target conceptual category (e.g. a fruit). The task comprised eight 30‐second trials. During the task, alpha band EEG was monitored at 15 locations. For the Wholist‐Analytic style, Analytics had, over all tasks, lower alpha power relative to the Wholists at all locations, and particularly posteriorly. With the Verbal‐Imagery dimension, there was style‐hemisphere effect, with Verbalisers having relatively more suppression on the left posterior temporal location T5 compared to right T6, and Imagers having the reverse. These results justify further exploration of the cerebral basis of individual differences in cognitive style.     

Reading,syntactic, and working memory skills of bilingual Portuguese-English Canadian children

The purpose of the study was to examine the nature of language, memory, and reading skills of bilingual students and to determine the relationship between reading problems in English and reading problems in Portuguese. The study assessed the reading, language, and memory skills of 37 bilingual Portuguese-Canadian children, aged 9–12 years. English was their main instructional language and Portuguese was the language spoken at home. All children attended a Heritage Language Program at school where they were taught to read and write Portuguese. The children were administered word and pseudoword reading, language, and working memory tasks in English and Portuguese. The majority of the children (67%) showed at least average proficiency in both languages. The children who had low reading scores in English also had significantly lower scores on the Portuguese tasks. There was a significant relationship between the acquisition of word and pseudoword reading, working memory, and syntactic awareness skills in the two languages. The Portuguese-Canadian children who were normally achieving readers did not differ from a comparison group of monolingual English speaking normally achieving readers except that the bilingual children had significantly lower scores on the English syntactic awareness task. The bilingual reading disabled children had similar scores to the monolingual reading disabled children on word reading and working memory but lower scores on the syntactic awareness task. However, the bilingual reading disabled children had significantlyhigher scores than the monolingual English speaking reading disabled children on the English pseudoword reading test and the English spelling task, perhaps reflecting a positive transfer from the more regular grapheme phoneme conversion rules of Portuguese. In this case, bilingualism does not appear to have negative consequences for the development of reading skills. In both English and Portuguese, reading difficulties appear to be strongly related to deficits in phonological processing.     

Differentiation of Two Working Memory Tasks Normed on a Large U.S. Sample of Children 2–7 Years Old

The Wechsler Preschool and Primary Scale of Intelligence, 4th ed. includes two measures of working memory normed on children 2;6–7;7. The present analyses of the typically developing children (N = 1,591, 812 female, 779 male, with an ethnic distribution approximating the United States) provide new, theoretically important information about these working memory tasks, Picture Memory and Zoo Locations. These new analyses establish developmental trends, individual-difference properties, and cognitive task properties. They show comparable developmental trends for the two tasks, but Picture Memory picks up more individual-difference variation and is more sensitive to knowledge. This analysis of normed tasks starting very young makes possible new methods for research on the early stages of childhood working memory development, about which little is currently known.     

改变音乐节拍对脑电功率谱变异的影响及其心理意义

目的旨在探索音乐节拍对大脑活动主要区域信息加工过程中的脑电波谱变异.方法采用自编的音乐播放软件给被试分别播放(42、65、120 BPM)3种音乐节拍的65 dB音乐,每种节拍曲目播放5 min,并采集16脑区的脑电信号进行离线分析.结果 (1)与安静状态相比播放音乐时被试在7个波段的脑电波谱功率显著降低;播放音乐时脑电波谱重心频率向低频段移动,表明疲劳程度增加;(2)改变音乐节拍显著降低α1波频段的功率而增加α2波频段的功率;(3)从频段功率占比看,加快音乐节拍节奏增加高频段脑电波活动,降低节拍节奏增加低频段活动而降低高频段脑电波活动.结论音乐节拍显著影响脑电波谱功率变异,65 BPM的中等节奏音乐有利于注意力集中和放松休息,120 BPM快节奏音乐有利于激活唤醒水平,加快运动,改变音乐节拍增加注意负荷,消耗更多的心理加工资源,其意义有待于进一步探索.     

The Role of Motor Competences in Predicting Working Memory Maintenance and Preparatory Processing

The purpose of the study was the examination of the longitudinal association between motor competences and changes in preparatory processing during a task requiring working memory maintenance. At baseline, 52 Caucasian children aged 10–12 years completed the MOBAK-5 test battery and a Sternberg task, whereas the cue-P300 and the initial contingent negative variation (iCNV) were recorded via electroencephalography. After 9 months, the Sternberg task was administered again to assess changes in these neurophysiological indices and behavioral performance. Path analyses revealed that motor competences predicted the change in cue-P300 and iCNV from baseline to follow-up. The present findings indicate that the cognitive control strategy during a task demanding working memory maintenance changes as a function of children's baseline motor competences.