scholarly journals Information flow across the cortical timescales hierarchy during narrative comprehension

2021 ◽  
Author(s):  
Claire H. C. Chang ◽  
Samuel A. Nastase ◽  
Uri Hasson

AbstractWhen listening to spoken narratives, we must integrate information over multiple, concurrent timescales, building up from words to phrases to sentences to a coherent narrative. Recent evidence suggests that the brain relies on a chain of hierarchically organized areas with increasing temporal receptive windows to process naturalistic narratives. In this study, we use inter-subject functional connectivity to reveal a stimulus-driven information flow along the cortical hierarchy. Using cross-correlation analysis to estimate the time lags between six functional networks, we found a fixed temporal sequence of information flow, starting in early auditory areas, followed language areas, the attention network, and lastly the default mode network. This gradient is consistent across eight distinct stories but absent in resting-state and scrambled story data, indicating that the lag gradient reflects the construction of narrative features. Finally, we simulate a variety of narrative integration models and demonstrate that nested narrative structure along with the gradual accumulation of information within the boundaries of linguistic events at each level of the processing hierarchy is sufficient to reproduce the lag gradient. Taken together, this study provides a computational framework for how information flows along the cortical hierarchy during narrative comprehension.

2021 ◽  
Author(s):  
Wei Wang ◽  
Yunzhong Shen ◽  
Fengwei Wang ◽  
Weiwei Li

<p>Climate change has led to increased droughts and floods over mainland Australia, resulting in water scarcity, excessive surplus and socioeconomic losses. Therefore, it is of great significance to comprehensively evaluate droughts and floods from the meteorological and hydrological perspective. Firstly, we determine the Standard Precipitation and Evapotranspiration Index (SPEI) by correlation analysis to represent the meteorological conditions. To characterize the hydrological conditions, we calculate the hydrological drought indices including Standard Runoff Index (SRI), Soil Moisture Deficit Index (SMDI), and Total Storage Deficit Index (TSDI), using the runoff and soil moisture data from the Global Land Data Assimilation System (GLDAS) and the Terrestrial Water Storage Change (TWSC) data from Gravity Recovery And Climate Experiment (GRACE) respectively. Results show that the most severe hydrological drought over mainland Australia during the study period occurred from May 2006 to Jan. 2009 with the drought severity of -58.28 (cm months) and the most severe flood from Jun. 2010 to Jan. 2013 is with the severity of 151.36 (cm months). The comprehensive analysis of both meteorological and hydrological drought indices shows that both meteorological and hydrological drought indices can effectively detect the droughts and floods over mainland Australia. Moreover, the meteorological drought and flood are of higher frequency, while hydrological drought and flood have a relatively longer duration. Based on the cross-correlation analysis, we find that the SPEI can firstly reflect the droughts or floods over mainland Australia, and then the SRI, SMDI and TSDI reflect with the time lags of one, three and six months respectively. Furthermore, we calculate the frequency of drought and flood at the basin scale and find that SPEI and SMDI are equally sensitive to drought and flood, while TSDI is more sensitive to flood than drought. This study reveals the relationship between meteorological and hydrological conditions in mainland Australia in the last two decades and highlights its intensifying extreme climate conditions under the circumstances of the increasing temperature and complex changing precipitation.</p>


2021 ◽  
Author(s):  
Chin-Hsien Cheng ◽  
Simon A. T. Redfern

Abstract. To understand the plethora of important processes that are characterized by their complexity, from global pandemics to global climate change, it may be critical to quantify causal contributions between time series variables. Here, we examine an empirical linear relationship between the rate of changing causes and effects with various multipliers. Sign corrected normalized information flow (nIFc) tends to provide the best estimates of causal contributions, often in situations where such causality is poorly reflected by regressions. These include: i) causal contributions with alternating feedback (correlation) sign, ii) significant causal time-lags, iii) significant noise contributions, and iv) comparison among many causes to an overall mean effect, especially with teleconnection. Estimates of methane-climate feedbacks with both observational and Earth system model CESM2 data are given as examples of nonlinear process quantification and model assessment. The relative causal contribution is hypothesized to be proportional to |nIF|, i.e. the ratio between entropy (degree of uncertainty) received from the cause-variable (i.e. information flow, |IF|) and the total entropy change of the effect-variable. Large entropy, associated with noise, deteriorates the estimates of total entropy change, and hence nIF, while the proportional relationship between the relative causal contribution and IF improves.


Author(s):  
Heli I. Koskinen ◽  
Rauno Rusko

This study focuses on emphasizing the instrumental role of stakeholder analysis and the concept of business ecosystem. Specifically, a stakeholder relationship might provide the channel for the particular instrumental targets of a business subset. This kind of stakeholder management is based on a principal-agent relationship between industry actors. However, this example, which focuses on horse entrepreneurs and the infectious diseases of this subset of the equine industry, shows that instead of a simple principal-agent relationship, stakeholder management might yield a chain of principal-agent relationships in the form of a principal-agent/principal-agent relationship (for example, one or more of the stakeholders simultaneously takes on the role of both agent and principal). According to the analysis, horse entrepreneurs have this kind of double role in stakeholder management for the prevention of infectious diseases.


2005 ◽  
Vol 15 (2) ◽  
pp. 293-349 ◽  
Author(s):  
KOHEI HONDA ◽  
NOBUKO YOSHIDA

This paper proposes new syntactic inference rules which can directly extract information flow in a given typed process in the π-calculus. In the flow analysis, a flow in a process is captured as a chain of possible interactions which transform differences in behaviours from one part of its interface to another part of its interface. Polarity in types plays a fundamental role in the analysis, which is elucidated via examples. We show that this inductive flow analysis can be used for giving simple proofs of noninterference in the secrecy analyses for the π-calculus with linear/affine typing, including its concurrent, stateful extensions.


2019 ◽  
Author(s):  
Caio Seguin ◽  
Adeel Razi ◽  
Andrew Zalesky

Neural information flow is inherently directional. To date, investigation of directional communication in the human structural connectome has been precluded by the inability of non-invasive neuroimaging methods to resolve axonal directionality. Here, we demonstrate that decentralized measures of network communication, applied to the undirected topology and geometry of brain networks, can predict putative directions of large-scale neural signalling. We propose the concept of send-receive communication asymmetry to characterize cortical regions as senders, receivers or neutral, based on differences between their incoming and outgoing communication efficiencies. Our results reveal a send-receive cortical hierarchy that recapitulates established organizational gradients differentiating sensory-motor and multimodal areas. We find that send-receive asymmetries are significantly associated with the directionality of effective connectivity derived from spectral dynamic causal modeling. Finally, using fruit fly, mouse and macaque connectomes, we provide further evidence suggesting that directionality of neural signalling is significantly encoded in the undirected architecture of nervous systems.


Water ◽  
2019 ◽  
Vol 11 (7) ◽  
pp. 1504 ◽  
Author(s):  
Min Zhang ◽  
Zhipan Niu ◽  
Qinghua Cai ◽  
Yaoyang Xu ◽  
Xiaodong Qu

Hydrodynamic conditions are considered to be very important in the control of algal blooms. Weekly or daily measurements may miss some important events in the hydrodynamic process, resulting in inaccurate evaluations of the impacts of hydrodynamics on phytoplankton. In this study, high-frequency (15-min interval) measurements were used to analyze the effect of water column stability on surface chlorophyll a (Chl a) and lag time under different nutrient backgrounds during a cyanobacterial bloom in the Three Gorges Reservoir, China. Cross-correlation analysis between the relative water column stability (RWCS) and Chl a was performed at different stages. The results showed that the RWCS above the euphotic depth influenced the surface Chl a concentration most significantly. A lower RWCS (<20) limited the increase in the Chl a concentration, and a higher RWCS caused a significant increase in Chl a only when nutrients were not limited (TN/TP < 29) and light and temperature conditions were suitable. It took a short time for a higher RWCS to significantly increase the surface Chl a concentration compared with a lower RWCS. When the waterbody had a very low Chl a concentration (almost 0), approximately 2 days were needed to significantly increase the Chl a concentration, while approximately only half an hour was needed when the background concentration of Chl a was slightly higher. During the bloom period, a decline in the RWCS significantly decreased the Chl a in a very short time (approximately half an hour). Reducing the water column stability could be a good approach to control cyanobacterial blooms.


Gripla ◽  
2021 ◽  
Vol 32 ◽  
pp. 227-256
Author(s):  
Katelin Parsons

The post-medieval revival of the annalistic format in Iceland in the early seventeenth century involved a deliberate and very successful decision to align contemporary history-writing with a long and venerable past tradition. Although the post-medieval annals were not structured around an Easter table like their medieval counterparts, they did not record secular history in a modern sense. Temporal time and space existed within an infinitely vaster eternity, and the true goal of earthly life was accepted to be salvation of the soul. Death was represented in meditative literature of the seventeenth century as a life-long journey rather than a single isolated event, during which journey divine punishments might be deservedly meted out to individuals and communities as corrective action for those who strayed from the straight and narrow path. In this context, annals were a means of situating the past, present and future within a single narrative space. Early modern Icelandic annals such as Skarðsárannáll, compiled by Björn Jónsson of Skarðsá (1574–1655), have been approached as a source of well-structured data on very diverse topics, but far fewer studies have examined their internal narrative structure across and within individual entries. The present article focuses on an entry for the year 1553 in Skarðsárannáll that provides a cautionary tale on discipline and justice for early modern audiences. The entry describes the misfortunes of Bjarni of Efranes in Skagaströnd, who killed his first wife for killing their older son for killing their younger son. What has to date been received as a gory historical account of a chain of deaths set in motion by a mother’s inappropriate threat to castrate her misbehaving young sons is actually a hitherto unknown Icelandic variant of a well-known tale type, AT 2401/ATU 1343* (“The Children Play at Hog-Killing”). Very close parallels can be found in contemporary folklore collected in the twentieth century (Brunvand 03250, “The Mother’s Threat Carried Out”), and the narrative in Skarðsárannáll supports the circulation of older versions of ATU 1343* involving a castration threat. Comparison with a letter written by Bishop Guðbrandur Þorláksson of Hólar suggests that the character of Bjarni of Efranes in Skarðsárannáll is partly based on a farmer in Skagaströnd whose son died suddenly while fishing with a neighbour and his three grown sons. The incident was not investigated as a possible murder case until many years later, but one of the sons was arrested in c. 1611. The bishop’s letter indicates concern that fair judicial procedure had not been followed in detaining the man, who was later released. There was no evidence that murder had taken place, and the accused swore that the young man had died of natural causes. The case was never prosecuted, but it was an unsatisfactory conclusion for all parties involved, and Skarðsárannáll demonstrates that the suspects were widely believed to be guilty within their local community. According to Skarðsárannáll, the neighbour and all three of his sons met a miserable end as starving vagrants in a famine soon thereafter. The narrative implies that death by famine is their punishment for the crime they attempted to conceal. Through the connection of this event to ATU 1343*, the narrative also suggests the guilt of the victim’s family as an explanation for the apparent failure of justice in the case: the victim is the third son of Bjarni of Efranes. Bjarni supposedly walked three times barefoot around Iceland as a penance for the sin of killing his first wife before settling at Efranes, but even this deed was inadequate justice for slaying his spouse, and his temporal life was one of a condemned man. Although he remarried and attempted to start a new life, murder carried the penalty of death, and penance was inadequate to atone for such an act in post-Reformation Iceland. Just as in other versions of ATU 1343* circulating in early modern Europe, Bjarni of Efranes died of grief. As this is a Lutheran exemplum, no saints could materialise to bring him comfort: the practice of life-long repentance was his only hope of salvation.


2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Szymon Smoliński ◽  
Adam Glazaczow

AbstractThe aims of this project were to study: diet composition, food selectivity and the phenology of different prey items in grayling’s (Thymallus thymallus) diet. It was hypothesized, that alterations in mayfly emergence, caused by reservoir-induced thermal changes, have consequences for trophic ecology of drift-feeding fish. Sampling of fish and macroinvertebrates were conducted in two closely located rivers, one human-modified and the other an undisturbed river. Grayling preyed mainly on aquatic insects, but only mayflies were preferred. Seasonal changes of the fish diet were observed, and air temperature is considered a predictor of prey occurrence with different time lags, depending on the biology of the organisms. Significant differences in the abundances and probability of mayfly occurrence between two studied rivers were shown. The observed phenological shift suggests that distorted environmental cues were experienced by the Ephemeroptera in the modified river. The “lost generation” of insects which failed to complete development became a new food for fish. The results presented indicate that reservoir-induced thermal alterations in the rivers, similarly to climate change, can lead to a chain of consequences in the ecosystems. Taking into consideration the projected climate scenarios, further monitoring and forecasting of these effects are considered an important step for future mitigating actions and adaptive management of water resources.


2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Caio Seguin ◽  
Adeel Razi ◽  
Andrew Zalesky

Abstract Neural information flow is inherently directional. To date, investigation of directional communication in the human structural connectome has been precluded by the inability of non-invasive neuroimaging methods to resolve axonal directionality. Here, we demonstrate that decentralized measures of network communication, applied to the undirected topology and geometry of brain networks, can infer putative directions of large-scale neural signalling. We propose the concept of send-receive communication asymmetry to characterize cortical regions as senders, receivers or neutral, based on differences between their incoming and outgoing communication efficiencies. Our results reveal a send-receive cortical hierarchy that recapitulates established organizational gradients differentiating sensory-motor and multimodal areas. We find that send-receive asymmetries are significantly associated with the directionality of effective connectivity derived from spectral dynamic causal modeling. Finally, using fruit fly, mouse and macaque connectomes, we provide further evidence suggesting that directionality of neural signalling is significantly encoded in the undirected architecture of nervous systems.


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