Theta Oscillations Support Prefrontal-hippocampal Interactions in Sequential Working Memory / 神经科学通报·英文版

The prefrontal cortex and hippocampus may support sequential working memory beyond episodic memory and spatial navigation. This stereoelectroencephalography (SEEG) study investigated how the dorsolateral prefrontal cortex (DLPFC) interacts with the hippocampus in the online processing of sequential information. Twenty patients with epilepsy (eight women, age 27.6 ± 8.2 years) completed a line ordering task with SEEG recordings over the DLPFC and the hippocampus. Participants showed longer thinking times and more recall errors when asked to arrange random lines clockwise (random trials) than to maintain ordered lines (ordered trials) before recalling the orientation of a particular line. First, the ordering-related increase in thinking time and recall error was associated with a transient theta power increase in the hippocampus and a sustained theta power increase in the DLPFC (3-10 Hz). In particular, the hippocampal theta power increase correlated with the memory precision of line orientation. Second, theta phase coherences between the DLPFC and hippocampus were enhanced for ordering, especially for more precisely memorized lines. Third, the theta band DLPFC → hippocampus influence was selectively enhanced for ordering, especially for more precisely memorized lines. This study suggests that theta oscillations may support DLPFC-hippocampal interactions in the online processing of sequential information.

Potential Role of Right Cerebellum in Post-stroke Aphasia: A Preliminary Study Based on Granger Causality Analysis / 中国康复理论与实践

Objective To explore the recovery mechanism of language network among post-stroke aphasic patients by investigating the difference of whole-brain amplitude of low frequency fluctuations (ALFF) and the Granger causality analysis (GCA) between the patients and the controls. Methods From May, 2019 to May, 2021, 19 patients with aphasia after left hemispheric stroke and 17 age- and sex- matched healthy controls finished functional magnetic resonance imaging scanning. All the patients assessed with Chinese version of Western Aphasia Battery (WAB). Restplus was used for fMRI data analysis. Regions with significant difference of ALFF between groups were chosen as regions of interests (ROI) for the following GCA analysis. Results ALFF in left inferior frontal gyrus triangle (LIFGtri) and left medial frontal gyrus (LMFG) were significantly lower in the patients than in the controls. Effective connectivity from LIFGtri to LMFG and from LMFG to the right cerebellar Crus I were significantly lower in the patients. Effective connectivity from right cerebellar Crus II to LIFGtri, from right cerebellar Crus I to LMFG were significantly greater in the patients. Conclusion Unidirectional negative regulatory pathway such as LIFGtri→LMFG might be injured in post-stroke aphasia, while, connectivities between right cerebellar Crus II→LIFGtri and right cerebellar Crus I →LMFG enhanced. Right cerebellum might be the potential target for the language recovery.

Potential Role of Right Cerebellum in Post-stroke Aphasia: A Preliminary Study Based on Granger Causality Analysis / 中国康复理论与实践

Objective To explore the recovery mechanism of language network among post-stroke aphasic patients by investigating the difference of whole-brain amplitude of low frequency fluctuations (ALFF) and the Granger causality analysis (GCA) between the patients and the controls. Methods From May, 2019 to May, 2021, 19 patients with aphasia after left hemispheric stroke and 17 age- and sex- matched healthy controls finished functional magnetic resonance imaging scanning. All the patients assessed with Chinese version of Western Aphasia Battery (WAB). Restplus was used for fMRI data analysis. Regions with significant difference of ALFF between groups were chosen as regions of interests (ROI) for the following GCA analysis. Results ALFF in left inferior frontal gyrus triangle (LIFGtri) and left medial frontal gyrus (LMFG) were significantly lower in the patients than in the controls. Effective connectivity from LIFGtri to LMFG and from LMFG to the right cerebellar Crus I were significantly lower in the patients. Effective connectivity from right cerebellar Crus II to LIFGtri, from right cerebellar Crus I to LMFG were significantly greater in the patients. Conclusion Unidirectional negative regulatory pathway such as LIFGtri→LMFG might be injured in post-stroke aphasia, while, connectivities between right cerebellar Crus II→LIFGtri and right cerebellar Crus I →LMFG enhanced. Right cerebellum might be the potential target for the language recovery.

Changes of Effective Connectivity in the Alpha Band Characterize Differential Processing of Audiovisual Information in Cross-Modal Selective Attention / 神经科学通报·英文版

Cross-modal selective attention enhances the processing of sensory inputs that are most relevant to the task at hand. Such differential processing could be mediated by a swift network reconfiguration on the macroscopic level, but this remains a poorly understood process. To tackle this issue, we used a behavioral paradigm to introduce a shift of selective attention between the visual and auditory domains, and recorded scalp electroencephalographic signals from eight healthy participants. The changes in effective connectivity caused by the cross-modal attentional shift were delineated by analyzing spectral Granger Causality (GC), a metric of frequency-specific effective connectivity. Using data-driven methods of pattern-classification and feature-analysis, we found that a change in the α band (12 Hz-15 Hz) of GC is a stable feature across different individuals that can be used to decode the attentional shift. Specifically, auditory attention induces more pronounced information flow in the α band, especially from the parietal-occipital areas to the temporal-parietal areas, compared to the case of visual attention, reflecting a reconfiguration of interaction in the macroscopic brain network accompanying different processing. Our results support the role of α oscillation in organizing the information flow across spatially-separated brain areas and, thereby, mediating cross-modal selective attention.

Changes of Effective Connectivity in the Alpha Band Characterize Differential Processing of Audiovisual Information in Cross-Modal Selective Attention / 神经科学通报·英文版

Cross-modal selective attention enhances the processing of sensory inputs that are most relevant to the task at hand. Such differential processing could be mediated by a swift network reconfiguration on the macroscopic level, but this remains a poorly understood process. To tackle this issue, we used a behavioral paradigm to introduce a shift of selective attention between the visual and auditory domains, and recorded scalp electroencephalographic signals from eight healthy participants. The changes in effective connectivity caused by the cross-modal attentional shift were delineated by analyzing spectral Granger Causality (GC), a metric of frequency-specific effective connectivity. Using data-driven methods of pattern-classification and feature-analysis, we found that a change in the α band (12 Hz-15 Hz) of GC is a stable feature across different individuals that can be used to decode the attentional shift. Specifically, auditory attention induces more pronounced information flow in the α band, especially from the parietal-occipital areas to the temporal-parietal areas, compared to the case of visual attention, reflecting a reconfiguration of interaction in the macroscopic brain network accompanying different processing. Our results support the role of α oscillation in organizing the information flow across spatially-separated brain areas and, thereby, mediating cross-modal selective attention.

Study on Chinese medicinal materials origin market integration--Taking Lonicerae Japonicae Flos, Lycii Fructus, Isatidis Radix and Pseudostellariae Radix for examples / 中草药

Trading volume in Chinese medicinal materials market has gradually declined, and origin market trade has become a trend. Studying the degree of market integration is helpful to understand the operation of origin market of Chinese medicinal materials, which is of great significance for rational planning of the production of Chinese medicinal materials and improving market efficiency. In this study, four varieties (Lonicerae Japonicae Flos, Lycii Fructus, Isatidis Radix and Pseudostellariae Radix) were selected to study the market integration degree of Chinese medicinal materials. Based on the price index data from 2013 to 2019, this paper makes an empirical analysis by using co-integration test, error correction model and Granger causality test. The results showed that the long-term integration of Chinese medicinal materials market was relatively high, but the short-term integration was far lower than the long-term integration. Finally, the author puts forward four policy suggestions: improving the price information platform conduction of Chinese medicinal materials, building high-quality brand of Chinese medicinal materials in non-authentic producing areas, speeding up the establishment quality traceability system and building modern logistics system of Chinese medicinal materials.

Research progress on analysis methods in electroencephalography-electromyography synchronous coupling / 生物医学工程学杂志

The motor nervous system transmits motion control information through nervous oscillations, which causes the synchronous oscillatory activity of the corresponding muscle to reflect the motion response information and give the cerebral cortex feedback, so that it can sense the state of the limbs. This synchronous oscillatory activity can reflect connectivity information of electroencephalography-electromyography (EEG-EMG) functional coupling. The strength of the coupling is determined by various factors including the strength of muscle contraction, attention, motion intention etc. It is very significant to study motor functional evaluation and control methods to analyze the changes of EEG-EMG synchronous coupling caused by different factors. This article mainly introduces and compares coherence and Granger causality of linear methods, the mutual information and transfer entropy of nonlinear methods in EEG-EMG synchronous coupling, and summarizes the application of each method, so that researchers in related fields can understand the current research progress on analysis methods of EEG-EMG synchronous systematically.

Resting-state Neural Networks and Granger Causal Connectivity for Patients with Cognitive Impairment Associated with Leukoaraiosis / 中国康复理论与实践

Objective:To compare the difference in resting state networks among leukoaraiosis (LA) patients with or without mild cognitive impairment, and healthy controls, as well as the functional connectivity under Granger causality analysis (GCA). Methods:Subjects aged 40 to 80 years, including 34 LA-MCI patients, 15 LA patients with normal cognition and 33 healthy controls, accepted resting-state functional magnetic resonance imaging. Independent component analysis was used to separate functional brain networks, and difference of activation was determined with two sample t-test. GCA was used to analyze effective connectivity of these functional networks. Results:Eight resting state networks were obtained, including default mode network, motor network, medial visual network, lateral visual network, right-memory network, left-memory network, auditory network and executive network. Activation was different among three groups. Effective connectivity of RSNs was also different among three groups. Conclusion:Components of the resting state networks keep changing as LA progressing. Activation decreases as patients' cognition impaired. The direction and strength of connections remodel.

The Causal Relationship Between Infant Mortality Rate, Health Expenditure And Economic Growth In India

The Infant Mortality Rate defined as the risk for a live born child to die before its first birthday, is known to be one of the most sensitive and commonly used indicators of the social and economic development of a nation. This paper investigates the causal relationship between infant mortality rate, economic growth and private health expenditure [% Gross Domestic Product (GDP)] in India using the co-integration and Granger causality frameworks for the period from 1995 to 2013 using secondary data from various sources. We have examined the presence of a long-run equilibrium relationship using the bounds testing approach to co-integration within the Unrestricted Error- Correction Model (UECM). We have also examined the direction of causality between infant mortality rate, economic growth and private health expenditure (% GDP) in India using the Granger causality test within the Vector Error-Correction Model (VECM). As a summary of the empirical findings, we find the Infant Mortality Rate (IMR), Per-Capita Gross Domestic Product (PCGDP) and private health expenditure (% GDP) are co-integrated. The results of Granger Causality suggested that no short-run effect was existing between all the three variables. The error-correction term implies that the variable is non-explosive and long-run equilibrium relationship is attainable.​​

Co-integration relation between residents’ health and economic development in China / 中国卫生政策研究

Objective:This paper aims to explore the relationship between the residents’ health and economic de-velopment to provide a scientific basis which will promote the coordinated economy and health development. Methods:Adopting the entropy method, we could calculate the comprehensive health evaluation index. In combining the co-inte-gration and error correction models, we could analyze the long-term and short-term relationships between our country residents’ level of health since 2000 and the national macro-economic development information. The Granger causality test served as a good method used in testing the casual relationships. Results: The health and economic development has a co-integration relationship which is -0. 6216 in the short-term correction. The economic development extent is the Granger cause of residents’ health status. Conclusion:There is not only a long-term equilibrium, but also a short-term relationship between the residents’ health and economic development in our country. The economic growth pro-motes residents’ health status while the promotion of residents’ health to economic growth is not obvious.

fMRI resting state time series causality: comparison of Granger causality and phase slope index.

Granger causality and Phase Slope Index (PSI) are recent approaches to measure how one signal depends on another, which gives an indication of information flow in complex systems. We show that the Granger causality and PSI mapping, voxel-by-voxel, for functional magnetic resonance imaging (fMRI) resting state data set. Slow fluctuations (< 0.1 Hz) in fMRI signal have been used to map several consistent resting state networks in the brain. The results demonstrate that PSI influence directions among reference regions and gray matter voxels were more consistent with the relevant previous studies compared with Granger causality. The PSI approach proposed is effective, computationally efficient, and easy to interpret.

Effect of scanner acoustic background noise on strict resting-state fMRI

Functional MRI (fMRI) resting-state experiments are aimed at identifying brain networks that support basal brain function. Although most investigators consider a ‘resting-state' fMRI experiment with no specific external stimulation, subjects are unavoidably under heavy acoustic noise produced by the equipment. In the present study, we evaluated the influence of auditory input on the resting-state networks (RSNs). Twenty-two healthy subjects were scanned using two similar echo-planar imaging sequences in the same 3T MRI scanner: a default pulse sequence and a reduced “silent” pulse sequence. Experimental sessions consisted of two consecutive 7-min runs with noise conditions (default or silent) counterbalanced across subjects. A self-organizing group independent component analysis was applied to fMRI data in order to recognize the RSNs. The insula, left middle frontal gyrus and right precentral and left inferior parietal lobules showed significant differences in the voxel-wise comparison between RSNs depending on noise condition. In the presence of low-level noise, these areas Granger-cause oscillations in RSNs with cognitive implications (dorsal attention and entorhinal), while during high noise acquisition, these connectivities are reduced or inverted. Applying low noise MR acquisitions in research may allow the detection of subtle differences of the RSNs, with implications in experimental planning for resting-state studies, data analysis, and ergonomic factors.

Transmissão e a influência do volume dos estoques públicos sobre o preço do arroz no Brasil / Transmission and influence of volume of public stocks on the price of rice in Brazil

Este trabalho analisou o mecanismo de transmissão dos preços dos principais estados produtores de arroz no Brasil (Rio Grande do Sul, Mato Grosso e Santa Catarina), como variáveis endógenas, e volume dos estoques públicos no Brasil, como variável exógena, para o período de julho de 2004 até dezembro de 2010. A análise compreende o uso da metodologia VAR-VEC para identificar o número de defasagens utilizadas e verificar se existem co-integrações entre as variáveis, por meio do Teste de Co-integração de Johansen. Testou-se a existência de causalidade entre as séries pelo método de causalidade de Granger. Aplicou-se a decomposição da variância do erro de previsão e a função impulso-resposta com decomposição de Cholesky para analisar a relação entre os preços dos estados e volume em estoques públicos. Com a aplicação da metodologia proposta, pode-se observar que o preço do arroz no estado do Rio Grande do Sul influencia no preço no estado de Santa Catarina e no volume armazenado em estoques públicos e é influenciado pelo preço do arroz no estado do Mato Grosso.

This study examined the mechanism of prices from major rice producing states in Brazil (Rio Grande do Sul, Mato Grosso and Santa Catarina), as endogenous variables, and volume of public stocks in Brazil, as exogenous variables for the period July 2004 until December 2010. The analysis includes the use of VAR-VEC methodology to identify the number of lags used and check for co-integration among variables through the test of Johansen Co-integration. We tested the existence of causality between variables by the method of Granger causality. We applied the variance decomposition of forecast error and impulse-response function with Cholesky decomposition to analyze the relationship between prices and volume of the states in public stocks. With the proposed methodology, one can observe that the price of rice in the state of Rio Grande do Sul to the price in the state of Santa Catarina and the volume stored in stockpiles and is influenced by the price of rice in the state of Mato Grosso.

Functional connectivity of EEG's delta-band in epilepsy interictal seizures based on Granger causality analysis / 国际生物医学工程杂志

ObjectiveThe purpose of this research was to investigate functional connectivity of 16-channel electroencephalograph(EEG) in δ frequency band based on Granger causality analysis.MethodsThe experimental data was recorded at a sampling rate of 200 Hz from temporal lobe epilepsy (TLE) patients(6 left and 3 right TLE,and 9 normals as control group.Ten of EEG segments of 20 s length for three different states:epileptiform discharges (ED) state in interictal durations,non-ED state for TLE patients,and control state for the normal.The δ band components (1～4 Hz) were filtered from EEGs.The functional connection values Iδ between two EEG δ components were calculated separately by Granger causality analysis.The two EEG components were from inferoposterior temporal lobe (left:T5,right:T6) to frontal lobe (Fp1,Fp2,F3,F4,and parietal lobe (C3,C4) for three states.ResultsThe Iδ values for ED state was 0.1323±0.0329～0.1670±0.028 9,which was significantly higher than that of non-ED state (0.0300±0.0130～0.0420±0.0072) (P＜0.05).The Iδ values for the control group (0.0153±0.0028～0.0193±0.0057) was much lower than that of ED state (P＜0.01),and no obvious distinctions were observed compared with non-ED state at P=0.05 level.ConclusionThere is a stronger connection of EEG' s δ bands from the inferoposterior temporal lobe to frontal and parietal lobe for the ED state,and the over-discharges transmission is from inferoposterior temporal lobe to other brain regions.There is a weaker connection from the top temporal lobe to frontal and parietal lobe for non-ED state and control group,and the onset zones is not inferoposterior temporal lobe.

Granger causality analysis methods on brain functional signals / 国际生物医学工程杂志

How does brain select and adjust the distributed neural activities to achieve its function? To address this problem,researchers introduce Granger causality analysis method to brain functional study,which deals with the estimation of causal influences among multi-variables.First,basic principles of Granger Causality and its improved algorithm structural vector autoregression (SVAR) are introduced.Then several technical problems are reviewed which should be noted when analyzing brain functional signals by Granger Causality Methods.In the end,the application foreground of Granger Causality in epilepsy localization is introduced by taking idiopathic generalized epilepsy as the example.