scholarly journals Parallel distributed networks dissociate episodic and social functions within the individual

2020 ◽  
Vol 123 (3) ◽  
pp. 1144-1179 ◽  
Author(s):  
Lauren M. DiNicola ◽  
Rodrigo M. Braga ◽  
Randy L. Buckner
Keyword(s):  
Theory Of Mind ◽  
Large Scale ◽  
Distributed Networks ◽  
Association Cortex ◽  
Default Network ◽  
Multiple Forms ◽  
Social Functions ◽  
Temporoparietal Junction ◽  
Parahippocampal Cortex ◽  
The Individual

Association cortex is organized into large-scale distributed networks. One such network, the default network (DN), is linked to diverse forms of internal mentation, opening debate about whether shared or distinct anatomy supports multiple forms of cognition. Using within-individual analysis procedures that preserve idiosyncratic anatomical details, we probed whether multiple tasks from two domains, episodic projection and theory of mind (ToM), rely on the same or distinct networks. In an initial experiment (6 subjects, each scanned 4 times), we found evidence that episodic projection and ToM tasks activate separate regions distributed throughout the cortex, with adjacent regions in parietal, temporal, prefrontal, and midline zones. These distinctions were predicted by the hypothesis that the DN comprises two parallel, interdigitated networks. One network, linked to parahippocampal cortex (PHC), is preferentially recruited during episodic projection, including both remembering and imagining the future. A second juxtaposed network, which includes the temporoparietal junction (TPJ), is differentially engaged during multiple forms of ToM. In two prospectively acquired independent experiments, we replicated and triplicated the dissociation (each with 6 subjects scanned 4 times). Furthermore, the dissociation was found in all zones when analyzed independently, including robustly in midline regions previously described as hubs. The TPJ-linked network is interwoven with the PHC-linked network across the cortex, making clear why it is difficult to fully resolve the two networks in group-averaged or lower-resolution data. These results refine our understanding of the functional-anatomical organization of association cortex and raise fundamental questions about how specialization might arise in parallel, juxtaposed association networks. NEW & NOTEWORTHY Two distributed, interdigitated networks exist within the bounds of the canonical default network. Here we used repeated scanning of individuals, across three independent samples, to provide evidence that tasks requiring episodic projection or theory of mind differentially recruit the two networks across multiple cortical zones. The two distributed networks thus appear to preferentially subserve distinct functions.

scholarly journals Parallel Distributed Networks Dissociate Episodic and Social Functions Within the Individual

2019 ◽  
Author(s):  
Lauren M. DiNicola ◽  
Rodrigo M. Braga ◽  
Randy L. Buckner
Keyword(s):  
Large Scale ◽  
Distributed Networks ◽  
Association Cortex ◽  
Multiple Forms ◽  
Social Functions ◽  
Temporoparietal Junction ◽  
Cortical Organization ◽  
Functional Regions ◽  
Parahippocampal Cortex ◽  
The Individual

Association cortex is organized into large-scale distributed networks. One such network, the default network (DN), is linked to diverse forms of internal mentation, opening debate about whether shared anatomy supports multiple forms of cognition. Alternatively, subtle distinctions in cortical organization could remain to be resolved. Using within-individual analysis procedures that preserve idiosyncratic details of cortical anatomy, we probed whether multiple tasks from two domains - Episodic Projection and Theory of Mind (ToM) - rely upon the same or distinct networks. In an initial experiment (n=6, subjects scanned 4 times each), we found evidence that Episodic Projection and ToM tasks activate distinct functional regions distributed throughout cortex, with adjacent regions in parietal, temporal, prefrontal and midline zones. These distinctions were predicted by the hypothesis that the DN comprises two parallel, interdigitated networks. One network, linked to parahippocampal cortex (PHC), is preferentially recruited during Episodic Projection, including both remembering the past and imagining the future. A second juxtaposed network, which includes the temporoparietal junction (TPJ), is differentially engaged during multiple forms of ToM tasks. The TPJ-linked network is interwoven with the PHC-linked network in multiple zones, including the posterior and anterior midline, making clear why it is difficult to fully resolve the two networks in group-averaged or lower-resolution data. We replicated all aspects of this network dissociation in a second, prospectively acquired dataset (n=6). These results refine our understanding of the functional-anatomical organization of association cortex as well as raise questions about how functional specialization might arise in parallel, juxtaposed association networks.

scholarly journals Parallel Distributed Networks Resolved at High Resolution Reveal Close Juxtaposition of Distinct Regions

2018 ◽  
Author(s):  
Rodrigo M. Braga ◽  
Koene R. A. Van Dijk ◽  
Jonathan R. Polimeni ◽  
Mark C. Eldaief ◽  
Randy L. Buckner
Keyword(s):  
High Resolution ◽  
Large Scale ◽  
Spatial Separation ◽  
Distributed Networks ◽  
Association Cortex ◽  
Default Network ◽  
Network Organization ◽  
Parahippocampal Cortex ◽  
The Individual ◽  
Insight Into

Examination of large-scale distributed networks within the individual reveals details of cortical network organization that are absent in group-averaged studies. One recent discovery is that a distributed transmodal network, often referred to as the ‘default network’, is comprised of two separate but closely interdigitated networks, only one of which is coupled to posterior parahippocampal cortex. Not all studies of individuals have identified the same networks and questions remain about the degree to which the two networks are separate, particularly within regions hypothesized to be interconnected hubs. Here we replicate the observation of network separation across analytical (seed-based connectivity and parcellation) and data projection (volume and surface) methods in 2 individuals each scanned 31 times. Additionally, 3 individuals were examined with high-resolution fMRI to gain further insight into the anatomical details. The two networks were identified with separate regions localized to adjacent portions of the cortical ribbon, sometimes inside the same sulcus. Midline regions previously implicated as hubs revealed near complete spatial separation of the two networks, displaying a complex spatial topography in the posterior cingulate and precuneus. The network coupled to parahippocampal cortex also revealed a separate region directly within the hippocampus at or near the subiculum. These collective results support that the default network is composed of at least two spatially juxtaposed networks. Fine spatial details and juxta-positions of the two networks can be identified within individuals at high resolution, providing insight into the network organization of association cortex and placing further constraints on interpretation of group-averaged neuroimaging data.

scholarly journals Parallel distributed networks resolved at high resolution reveal close juxtaposition of distinct regions

2019 ◽  
Vol 121 (4) ◽  
pp. 1513-1534 ◽  
Author(s):  
Rodrigo M. Braga ◽  
Koene R. A. Van Dijk ◽  
Jonathan R. Polimeni ◽  
Mark C. Eldaief ◽  
Randy L. Buckner
Keyword(s):  
High Resolution ◽  
Large Scale ◽  
Hippocampal Formation ◽  
Spatial Separation ◽  
Distributed Networks ◽  
Association Cortex ◽  
Default Network ◽  
Network Organization ◽  
Parahippocampal Cortex ◽  
Insight Into

Examination of large-scale distributed networks within the individual reveals details of cortical network organization that are absent in group-averaged studies. One recent discovery is that a distributed transmodal network, often referred to as the “default network,” comprises two closely interdigitated networks, only one of which is coupled to posterior parahippocampal cortex. Not all studies of individuals have identified the same networks, and questions remain about the degree to which the two networks are separate, particularly within regions hypothesized to be interconnected hubs. In this study we replicate the observation of network separation across analytical (seed-based connectivity and parcellation) and data projection (volume and surface) methods in two individuals each scanned 31 times. Additionally, three individuals were examined with high-resolution (7T; 1.35 mm) functional magnetic resonance imaging to gain further insight into the anatomical details. The two networks were identified with separate regions localized to adjacent portions of the cortical ribbon, sometimes inside the same sulcus. Midline regions previously implicated as hubs revealed near complete spatial separation of the two networks, displaying a complex spatial topography in the posterior cingulate and precuneus. The network coupled to parahippocampal cortex also revealed a separate region directly within the hippocampus, at or near the subiculum. These collective results support that the default network is composed of at least two spatially juxtaposed networks. Fine spatial details and juxtapositions of the two networks can be identified within individuals at high resolution, providing insight into the network organization of association cortex and placing further constraints on interpretation of group-averaged neuroimaging data. NEW & NOTEWORTHY Recent evidence has emerged that canonical large-scale networks such as the “default network” fractionate into parallel distributed networks when defined within individuals. This research uses high-resolution imaging to show that the networks possess juxtapositions sometimes evident inside the same sulcus and within regions that have been previously hypothesized to be network hubs. Distinct circumscribed regions of one network were also resolved in the hippocampal formation, at or near the parahippocampal cortex and subiculum.

scholarly journals Situating the Left-Lateralized Language Network in the Broader Organization of Multiple Specialized Large-Scale Distributed Networks

2019 ◽  
Author(s):  
Rodrigo M. Braga ◽  
Lauren M. DiNicola ◽  
Randy L. Buckner
Keyword(s):  
Large Scale ◽  
Temporal Cortex ◽  
Distributed Networks ◽  
Inferior Temporal Cortex ◽  
Association Cortex ◽  
Candidate Network ◽  
Motor Region ◽  
Classical Language ◽  
The Individual ◽  
Language Network

Using procedures optimized to explore network organization within the individual, the topography of a candidate language network was characterized and situated within the broader context of adjacent networks. The candidate network was first identified using functional connectivity and replicated across individuals, datasets, acquisition tasks, and analytic methods. In addition to classical language regions near to perisylvian cortex and temporal pole, additional regions were observed in dorsal posterior cingulate, midcingulate, anterior superior frontal and inferior temporal cortex. The candidate network was selectively activated when processing meaningful (as contrast to non-word) sentences, while spatially adjacent networks showed minimal or even decreased activity. Examined in relation to adjacent networks, the topography of the language network was found to parallel the motif of other association networks including the transmodal association networks linked to theory of mind and episodic remembering (often collectively called the default network). The several networks contained juxtaposed regions in multiple association zones. Outside of these juxtaposed higher-order networks, we further noted a distinct frontotemporal network situated between language regions and a frontal orofacial motor region and a temporal auditory region. A possibility is that these functionally-related sensorimotor regions might anchor specialization of neighboring association regions that develop into the language network. What is most striking is that the canonical language network appears to be just one of multiple similarly organized, differentially specialized distributed networks that populate the evolutionarily expanded zones of human association cortex.

scholarly journals Situating the left-lateralized language network in the broader organization of multiple specialized large-scale distributed networks

2020 ◽  
Vol 124 (5) ◽  
pp. 1415-1448 ◽  
Author(s):  
Rodrigo M. Braga ◽  
Lauren M. DiNicola ◽  
Hannah C. Becker ◽  
Randy L. Buckner
Keyword(s):  
Functional Connectivity ◽  
Large Scale ◽  
Distributed Networks ◽  
Task Demands ◽  
Association Cortex ◽  
Control Networks ◽  
Language Network

This research shows that a language network can be identified within individuals using functional connectivity. Organizational details reveal that the language network shares a common spatial motif with other association networks, including default and frontoparietal control networks. The language network is activated by language task demands, whereas closely juxtaposed networks are not, suggesting that similarly organized but differentially specialized distributed networks populate association cortex.

scholarly journals The organization of the human cerebral cortex estimated by intrinsic functional connectivity

2011 ◽  
Vol 106 (3) ◽  
pp. 1125-1165 ◽  
Author(s):  
B. T. Thomas Yeo ◽  
Fenna M. Krienen ◽  
Jorge Sepulcre ◽  
Mert R. Sabuncu ◽  
Danial Lashkari ◽  
...  
Keyword(s):  
Cerebral Cortex ◽  
Functional Connectivity ◽  
Large Scale ◽  
Distributed Networks ◽  
Association Cortex ◽  
Resting State Functional Connectivity ◽  
Local Networks ◽  
Temporal Area ◽  
Hierarchical Relations ◽  
Connectivity Patterns

Information processing in the cerebral cortex involves interactions among distributed areas. Anatomical connectivity suggests that certain areas form local hierarchical relations such as within the visual system. Other connectivity patterns, particularly among association areas, suggest the presence of large-scale circuits without clear hierarchical relations. In this study the organization of networks in the human cerebrum was explored using resting-state functional connectivity MRI. Data from 1,000 subjects were registered using surface-based alignment. A clustering approach was employed to identify and replicate networks of functionally coupled regions across the cerebral cortex. The results revealed local networks confined to sensory and motor cortices as well as distributed networks of association regions. Within the sensory and motor cortices, functional connectivity followed topographic representations across adjacent areas. In association cortex, the connectivity patterns often showed abrupt transitions between network boundaries. Focused analyses were performed to better understand properties of network connectivity. A canonical sensory-motor pathway involving primary visual area, putative middle temporal area complex (MT+), lateral intraparietal area, and frontal eye field was analyzed to explore how interactions might arise within and between networks. Results showed that adjacent regions of the MT+ complex demonstrate differential connectivity consistent with a hierarchical pathway that spans networks. The functional connectivity of parietal and prefrontal association cortices was next explored. Distinct connectivity profiles of neighboring regions suggest they participate in distributed networks that, while showing evidence for interactions, are embedded within largely parallel, interdigitated circuits. We conclude by discussing the organization of these large-scale cerebral networks in relation to monkey anatomy and their potential evolutionary expansion in humans to support cognition.

scholarly journals Macroscale Cortical Organization and a Default-Like Transmodal Apex Network in the Marmoset Monkey

2018 ◽  
Author(s):  
Randy L. Buckner ◽  
Daniel S. Margulies
Keyword(s):  
Temporal Cortex ◽  
Association Cortex ◽  
Temporal Association ◽  
Default Network ◽  
Social Functions ◽  
Cortical Organization ◽  
Marmoset Monkey ◽  
Parietal Association Cortex ◽  
Human Association ◽  
Posterior Midline

Networks of widely distributed regions populate human association cortex. One network, often called the default network, is positioned at the apex of a gradient of sequential networks that radiate outward from primary cortex. Here extensive anatomical data made available through the Marmoset Brain Architecture Project were explored to determine if a homologue exists in marmoset. Results revealed that a gradient of networks extend outward from primary cortex to progressively higher-order transmodal association cortex in both frontal and temporal cortex. The transmodal apex network comprises frontopolar and rostral temporal association cortex, parahippocampal areas TH / TF, the ventral posterior midline, and lateral parietal association cortex. The positioning of this network in the gradient and its composition of areas make it a candidate homologue to the human default network. That the marmoset, a physiologically- and genetically-accessible primate, might possess a default-network-like candidate creates opportunities for study of higher cognitive and social functions.

Models, Practices and Methods of Reading: Evolution in Time and Space

2009 ◽  
pp. 59-64
Author(s):  
Yulia P. Melentyeva
Keyword(s):  
Large Scale ◽  
Social Groups ◽  
National Program ◽  
Time And Space ◽  
Lack Of Information ◽  
The Individual

In recent years as public in general and specialist have been showing big interest to the matters of reading. According to discussion and launch of the “Support and Development of Reading National Program”, many Russian libraries are organizing the large-scale events like marathons, lecture cycles, bibliographic trainings etc. which should draw attention of different social groups to reading. The individual forms of attraction to reading are used much rare. To author’s mind the main reason of such an issue has to be the lack of information about forms and methods of attraction to reading.

Flexibility Effects in a Single Link Robotic Manipulator

1993 ◽  
Author(s):  
C. Nataraj
Keyword(s):  
Large Scale ◽  
Robotic Manipulator ◽  
Flexible Beam ◽  
Rotating Speed ◽  
Weighted Residuals ◽  
Individual Interaction ◽  
Single Link ◽  
Rigid Mass ◽  
The Individual ◽  
Future Work

Abstract A single link robotic manipulator is modeled as a rotating flexible beam with a rigid mass at the tip and accurate energy expressions are derived. The resulting partial differential equations are solved using an approximate method of weighted residuals. From the solutions, coupling between axial and flexural deformations and the interactions with rigid body motions are rigorously analyzed. The emphasis in the current paper is not on an exhaustive analysis of existing systems but it is rather intended to compare and highlight the various flexibility effects in a relatively simple system. Hence, a nondimensional parametric analysis is performed to determine the effect of several parameters (including the rotating speed) on the errors and the individual interaction effects are discussed. Comparison with previous work in the field shows important phenomena often ignored or buried in large scale numerical analyses. Future work including application to multi-link robots is outlined.

scholarly journals HUMAN ENERGY UTILIZATION AND EFFECTIVENESS IN SMALL AND MARGINAL FARM HOLDINGS

2018 ◽  
Vol 6 (11) ◽  
pp. 163-171
Author(s):  
Tandra Mondal ◽  
Pranab Kumar Nag
Keyword(s):  
Large Scale ◽  
Energy Utilization ◽  
Hand Tools ◽  
Present Contribution ◽  
Land Preparation ◽  
Farm Work ◽  
Farm Mechanization ◽  
Power Tiller ◽  
Paddy Cultivation ◽  
The Individual

In India, small and marginal farmers have emerged as a distinct and dominant category. While farm mechanization represents a rapid transformation from traditional to modern methods of farming, it is not uniform across the crops and regions. The level of mechanization, however, remains scattered due to the compulsiveness to the situation dominated by the economic layout of farm holdings, land size, and large-scale deprivation of access to the technology suitable to small holdings. This present contribution elucidates the extent of use tools and machinery among the rice farmers of the state of Wes Bengal, India. Analysis revealed that the total number of man-days involved in paddy cultivation was 120-140 per ha, i.e., 900-1000 man-hours depending upon the availability of labour, tools, and machinery used for the individual operation. Analysis of farm work in small and marginal holdings evolved that over 90% of the total number of farmers use either tractor or power tiller for land preparation. Use of the animal-drawn country plough is gradually phased out in the study regions. For sowing and transplanting operations are primarily manual methods using hand tools. The study provided an insight of the issues of work methods and practices of the farmworkers in small and marginal farm holdings.

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