The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform

Giuliana Mazzoni - One of the best experts on this subject based on the ideXlab platform.

  • brain activation in highly superior autobiographical memory the role of the precuneus in the autobiographical memory retrieval network
    Cortex, 2019
    Co-Authors: Adriana De Bartolo, Zacharia Nahouli, Davide Duzzi, Matteo De Marco, Giuliana Mazzoni, Andrew Clark, William J. Mcgeown, Chiara Guerrini, Annalena Venneri
    Abstract:

    Abstract This is the first study to examine functional brain activation in a single case of Highly Superior Autobiographical Memory (HSAM) who shows no sign of obsessive compulsive disorder (OCD). While previous work has documented the existence of HSAM, information about brain areas involved in this exceptional form of memory for personal events relies on structural and resting state Connectivity Data, with mixed results so far. In this first task-based functional magnetic resonance Imaging (fMRI) study of a normal individual with HSAM, dates were presented as cues and two phases were assessed during memory retrieval, initial access and later elaboration. Results showed that initial access was very fast, did not activate the hippocampus, and involved activation of predominantly posterior visual areas, including the precuneus. These areas typically become active during later stages of elaboration of personal memories rather than during initial access. Elaboration involved a balanced bilateral activation of most of the autobiographical network areas, rather than the more typical shifts observed in people without HSAM. Overall, the pattern of brain activations, which rests on repeated observations in a single individual, highlights a strong involvement of the precuneus and an idiosyncratic initial access to personal memory representations. Implications for the nature of personal memories in HSAM are discussed.

  • brain activation in highly superior autobiographical memory the role of the precuneus in the autobiographical memory retrieval network
    Cortex, 2019
    Co-Authors: Adriana De Bartolo, Zacharia Nahouli, Davide Duzzi, Matteo De Marco, Giuliana Mazzoni, Andrew Clark, William J. Mcgeown, Chiara Guerrini, Annalena Venneri
    Abstract:

    Abstract This is the first study to examine functional brain activation in a single case of Highly Superior Autobiographical Memory (HSAM) who shows no sign of obsessive compulsive disorder (OCD). While previous work has documented the existence of HSAM, information about brain areas involved in this exceptional form of memory for personal events relies on structural and resting state Connectivity Data, with mixed results so far. In this first task-based functional magnetic resonance Imaging (fMRI) study of a normal individual with HSAM, dates were presented as cues and two phases were assessed during memory retrieval, initial access and later elaboration. Results showed that initial access was very fast, did not activate the hippocampus, and involved activation of predominantly posterior visual areas, including the precuneus. These areas typically become active during later stages of elaboration of personal memories rather than during initial access. Elaboration involved a balanced bilateral activation of most of the autobiographical network areas, rather than the more typical shifts observed in people without HSAM. Overall, the pattern of brain activations, which rests on repeated observations in a single individual, highlights a strong involvement of the precuneus and an idiosyncratic initial access to personal memory representations. Implications for the nature of personal memories in HSAM are discussed.

Eric A. Treml - One of the best experts on this subject based on the ideXlab platform.

  • operationalizing ecological Connectivity in spatial conservation planning with marxan connect
    Methods in Ecology and Evolution, 2020
    Co-Authors: Anna Metaxas, Arieanna C Balbar, Caitlin D Kuempel, Jennifer Mcgowan, Rémi M. Daigle, Eric A. Treml, Hugh P. Possingham
    Abstract:

    Globally, protected areas are being established to protect biodiversity and to promote ecosystem resilience. The typical spatial conservation planning process leading to the creation of these protected areas focuses on representation and replication of ecological features, often using decision support tools such as Marxan. Yet, despite the important role ecological Connectivity has in metapopulation persistence and resilience, Marxan currently requires manual input or specialized scripts to explicitly consider Connectivity. ‘Marxan Connect’ is a new open source, open access Graphical User Interface (GUI) tool designed to assist conservation planners with the appropriate use of Data on ecological Connectivity in protected area network planning. Marxan Connect can facilitate the use of estimates of demographic Connectivity (e.g. derived from animal tracking Data, dispersal models, or genetic tools) or structural landscape Connectivity (e.g. isolation by resistance). This is accomplished by calculating metapopulation-relevant Connectivity metrics (e.g. eigenvector centrality) and treating those as conservation features or by including the Connectivity Data as a spatial dependency amongst sites in the prioritization process. Marxan Connect allows a wide group of users to incorporate directional ecological Connectivity into conservation planning with Marxan. The solutions provided by Marxan Connect, combined with ecologically relevant post-hoc testing, are more likely to support persistent and resilient metapopulations (e.g. fish stocks) and provide better protection for biodiversity.

  • operationalizing ecological Connectivity in spatial conservation planning with marxan connect
    bioRxiv, 2018
    Co-Authors: Rémi M. Daigle, Anna Metaxas, Arieanna C Balbar, Caitlin D Kuempel, Jennifer Mcgowan, Eric A. Treml, Hugh P. Possingham, Maria Beger
    Abstract:

    Globally, protected areas are being established to protect biodiversity and to promote ecosystem resilience. The typical spatial conservation planning process leading to the creation of these protected areas focuses on representation and replication of ecological features, often using decision support systems such as Marxan. Unfortunately, Marxan currently requires manual input or specialised scripts to explicitly consider ecological Connectivity, a property critical to metapopulation persistence and resilience. "Marxan Connect" is a new open source, open access Graphical User Interface (GUI) designed to assist conservation planners in the systematic operationalization of ecological Connectivity in protected area network planning. Marxan Connect is able to incorporate estimates of demographic Connectivity (e.g. derived from tracking Data, dispersal models, or genetics) or structural landscape Connectivity (e.g. isolation by resistance). This is accomplished by calculating metapopulation-relevant Connectivity metrics (e.g. eigenvector centrality) and treating those as conservation features, or using the Connectivity Data as a spatial dependency amongst sites to be included in the prioritization process. Marxan Connect allows a wide group of users to incorporate directional ecological Connectivity into conservation plans. The least-cost conservation solutions provided by Marxan Connect, combined with ecologically relevant post-hoc testing, are more likely to support persistent and resilient metapopulations (e.g. fish stocks) and provide better protection for biodiversity than if Connectivity is ignored.

  • marine population Connectivity identifies ecological neighbors for conservation planning in the coral triangle
    Conservation Letters, 2012
    Co-Authors: Eric A. Treml, Patrick N Halpin
    Abstract:

    Robust conservation plans seek to accommodate functional Connectivity by establishing regional priorities and through decisions regarding the size and placement of protected areas. In marine systems, Connectivity refers to the ecological linkages (primarily larval dispersal) between populations and protected areas. Unfortunately, Connectivity Data for the majority of populations are unavailable, requiring managers to rely on expert knowledge and general "scale" and "distance" guidelines. We present a novel approach for integrating model-based Connectivity estimates into the conservation planning framework. We quantify multispecies Connectivity across the Indo-Pacific and demonstrate how this informs conservation planning in the Coral Triangle across three levels: countries, ecoregions, and priority seascapes. The emergent network structure of ecological linkages between planning regions complements the current bioregionalization across the Coral Triangle. This new ecological network perspective will help (re)define partnerships and assist in coordinating policy actions, ultimately leading to a more effective planning process.

Annalena Venneri - One of the best experts on this subject based on the ideXlab platform.

  • brain activation in highly superior autobiographical memory the role of the precuneus in the autobiographical memory retrieval network
    Cortex, 2019
    Co-Authors: Adriana De Bartolo, Zacharia Nahouli, Davide Duzzi, Matteo De Marco, Giuliana Mazzoni, Andrew Clark, William J. Mcgeown, Chiara Guerrini, Annalena Venneri
    Abstract:

    Abstract This is the first study to examine functional brain activation in a single case of Highly Superior Autobiographical Memory (HSAM) who shows no sign of obsessive compulsive disorder (OCD). While previous work has documented the existence of HSAM, information about brain areas involved in this exceptional form of memory for personal events relies on structural and resting state Connectivity Data, with mixed results so far. In this first task-based functional magnetic resonance Imaging (fMRI) study of a normal individual with HSAM, dates were presented as cues and two phases were assessed during memory retrieval, initial access and later elaboration. Results showed that initial access was very fast, did not activate the hippocampus, and involved activation of predominantly posterior visual areas, including the precuneus. These areas typically become active during later stages of elaboration of personal memories rather than during initial access. Elaboration involved a balanced bilateral activation of most of the autobiographical network areas, rather than the more typical shifts observed in people without HSAM. Overall, the pattern of brain activations, which rests on repeated observations in a single individual, highlights a strong involvement of the precuneus and an idiosyncratic initial access to personal memory representations. Implications for the nature of personal memories in HSAM are discussed.

  • brain activation in highly superior autobiographical memory the role of the precuneus in the autobiographical memory retrieval network
    Cortex, 2019
    Co-Authors: Adriana De Bartolo, Zacharia Nahouli, Davide Duzzi, Matteo De Marco, Giuliana Mazzoni, Andrew Clark, William J. Mcgeown, Chiara Guerrini, Annalena Venneri
    Abstract:

    Abstract This is the first study to examine functional brain activation in a single case of Highly Superior Autobiographical Memory (HSAM) who shows no sign of obsessive compulsive disorder (OCD). While previous work has documented the existence of HSAM, information about brain areas involved in this exceptional form of memory for personal events relies on structural and resting state Connectivity Data, with mixed results so far. In this first task-based functional magnetic resonance Imaging (fMRI) study of a normal individual with HSAM, dates were presented as cues and two phases were assessed during memory retrieval, initial access and later elaboration. Results showed that initial access was very fast, did not activate the hippocampus, and involved activation of predominantly posterior visual areas, including the precuneus. These areas typically become active during later stages of elaboration of personal memories rather than during initial access. Elaboration involved a balanced bilateral activation of most of the autobiographical network areas, rather than the more typical shifts observed in people without HSAM. Overall, the pattern of brain activations, which rests on repeated observations in a single individual, highlights a strong involvement of the precuneus and an idiosyncratic initial access to personal memory representations. Implications for the nature of personal memories in HSAM are discussed.

Xiao-jing Wang - One of the best experts on this subject based on the ideXlab platform.

  • feedforward and feedback frequency dependent interactions in a large scale laminar network of the primate cortex
    Science Advances, 2016
    Co-Authors: Jorge F Mejias, Henry Kennedy, Xiao-jing Wang, John D Murray
    Abstract:

    Interactions between top-down and bottom-up processes in the cerebral cortex hold the key to understanding attentional processes, predictive coding, executive control, and a gamut of other brain functions. However, the underlying circuit mechanism remains poorly understood and represents a major challenge in neuroscience. We approached this problem using a large-scale computational model of the primate cortex constrained by new directed and weighted Connectivity Data. In our model, the interplay between feedforward and feedback signaling depends on the cortical laminar structure and involves complex dynamics across multiple (intralaminar, interlaminar, interareal, and whole cortex) scales. The model was tested by reproducing, as well as providing insights into, a wide range of neurophysiological findings about frequency-dependent interactions between visual cortical areas, including the observation that feedforward pathways are associated with enhanced gamma (30 to 70 Hz) oscillations, whereas feedback projections selectively modulate alpha/low-beta (8 to 15 Hz) oscillations. Furthermore, the model reproduces a functional hierarchy based on frequency-dependent Granger causality analysis of interareal signaling, as reported in recent monkey and human experiments, and suggests a mechanism for the observed context-dependent hierarchy dynamics. Together, this work highlights the necessity of multiscale approaches and provides a modeling platform for studies of large-scale brain circuit dynamics and functions.

  • feedforward and feedback frequency dependent interactions in a large scale laminar network of the primate cortex
    bioRxiv, 2016
    Co-Authors: Jorge F Mejias, Henry Kennedy, John D Murray, Xiao-jing Wang
    Abstract:

    Interactions between top-down and bottom-up processes in the cerebral cortex hold the key to understanding predictive coding, executive control and a gamut of other brain functions. The underlying circuit mechanism, however, remains poorly understood and represents a major challenge in neuroscience. In the present work we tackled this problem using a large-scale computational model of the primate cortex constrained by new directed and weighted Connectivity Data. In our model, the interplay between feedforward and feedback signaling depends on the cortical laminar structure and involves complex dynamics across multiple (intra-laminar, inter-laminar, inter-areal and whole cortex) scales. The model was tested by reproducing, and shedding insights into, a wide range of neurophysiological findings about frequency-dependent interactions between visual cortical areas: feedforward pathways are associated with enhanced gamma (30-70 Hz) oscillations, whereas feedback projections selectively modulate alpha/low beta (8-15 Hz) oscillations. We found that in order for the model to account for the experimental observations, the feedback projection needs to predominantly target infragranular layers in a target area, which leads to a proposed circuit substrate for predictive coding. The model reproduces a functional hierarchy based on frequency-dependent Granger causality analysis of inter-areal signaling, as reported in recent monkey and human experiments. Taken together, this work highlights the importance of multi-scale approaches and provides a modeling platform for studies of large-scale brain circuit dynamics and functions.

  • A Large-Scale Circuit Mechanism for Hierarchical Dynamical Processing in the Primate Cortex
    Neuron, 2015
    Co-Authors: Rishidev Chaudhuri, Henry Kennedy, Kenneth Knoblauch, Marie Alice Gariel, Xiao-jing Wang
    Abstract:

    We developed a large-scale dynamical model of the macaque neocortex, which is based on recently acquired directed- and weighted-Connectivity Data from tract-tracing experiments, and which incorporates heterogeneity across areas. A hierarchy of timescales naturally emerges from this system: sensory areas show brief, transient responses to input (appropriate for sensory processing), whereas association areas integrate inputs over time and exhibit persistent activity (suitable for decision-making and working memory). The model displays multiple temporal hierarchies, as evidenced by contrasting responses to visual versus somatosensory stimulation. Moreover, slower prefrontal and temporal areas have a disproportionate impact on global brain dynamics. These findings establish a circuit mechanism for "temporal receptive windows" that are progressively enlarged along the cortical hierarchy, suggest an extension of time integration in decision making from local to large circuits, and should prompt a re-evaluation of the analysis of functional Connectivity (measured by fMRI or electroencephalography/magnetoencephalography) by taking into account inter-areal heterogeneity.

  • a large scale circuit mechanism for hierarchical dynamical processing in the primate cortex
    bioRxiv, 2015
    Co-Authors: Rishidev Chaudhuri, Henry Kennedy, Kenneth Knoblauch, Marie Alice Gariel, Xiao-jing Wang
    Abstract:

    We developed a large-scale dynamical model of the macaque neocortex based on recent quantitative Connectivity Data. A hierarchy of timescales naturally emerges from this system: sensory areas show brief, transient responses to input (appropriate for sensory processing), whereas association areas integrate inputs over time and exhibit persistent activity (suitable for decision-making and working memory). The model displays multiple temporal hierarchies, as evidenced by contrasting responses to visual and somatosensory stimulation. Moreover, slower prefrontal and temporal areas have a disproportionate impact on global brain dynamics. These findings establish for the first time a circuit mechanism for "temporal receptive windows" that are progressively enlarged along the cortical hierarchy, extend the concept of working memory from local to large circuits, and suggest a re-interpretation of functional Connectivity measures.

Markus Diesmann - One of the best experts on this subject based on the ideXlab platform.

  • the cell type specific cortical microcircuit relating structure and activity in a full scale spiking network model
    Cerebral Cortex, 2014
    Co-Authors: Tobias C Potjans, Markus Diesmann
    Abstract:

    In the past decade, the cell-type specific Connectivity and activity of local cortical networks have been characterized experimentally to some detail. In parallel, modeling has been established as a tool to relate network structure to activity dynamics. While available comprehensive Connectivity maps ( Thomson, West, et al. 2002; Binzegger et al. 2004) have been used in various computational studies, prominent features of the simulated activity such as the spontaneous firing rates do not match the experimental findings. Here, we analyze the properties of these maps to compile an integrated Connectivity map, which additionally incorporates insights on the specific selection of target types. Based on this integrated map, we build a full-scale spiking network model of the local cortical microcircuit. The simulated spontaneous activity is asynchronous irregular and cell-type specific firing rates are in agreement with in vivo recordings in awake animals, including the low rate of layer 2/3 excitatory cells. The interplay of excitation and inhibition captures the flow of activity through cortical layers after transient thalamic stimulation. In conclusion, the integration of a large body of the available Connectivity Data enables us to expose the dynamical consequences of the cortical microcircuitry.

  • cocomac 2 0 and the future of tract tracing Databases
    Frontiers in Neuroinformatics, 2012
    Co-Authors: Rembrandt Bakker, Thomas Wachtler, Markus Diesmann
    Abstract:

    The CoCoMac Database contains the results of several hundred published axonal tract-tracing studies in the macaque monkey brain. The combined results are used for constructing the macaque macro-connectome. Here we discuss the redevelopment of CoCoMac and compare it to six connectome-related projects: two online resources that provide full access to raw tracing Data in rodents, a connectome viewer for advanced 3D graphics, a partial but highly detailed rat connectome, a brain Data management system that generates custom Connectivity matrices, and a software package that covers the complete pipeline from Connectivity Data to large-scale brain simulations. The second edition of CoCoMac features many enhancements over the original. For example, a search wizard is provided for full access to all tables and their nested dependencies. Connectivity matrices can be computed on demand in a user-selected nomenclature. A new Data entry system is available as a preview, and is to become a generic solution for community-driven Data entry in manually collated Databases. We conclude with the question whether neuronal tracing will remain the gold standard to uncover the wiring of brains, thereby highlighting developments in human connectome construction, tracer substances, polarized light imaging, and serial block-face scanning electron microscopy.