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Lee Cossell - One of the best experts on this subject based on the ideXlab platform.

  • functional organization of excitatory synaptic strength in primary visual cortex
    Nature, 2015
    Co-Authors: Lee Cossell, Maria Florencia Iacaruso, Dylan R Muir, Rachael Houlton, Elie Sader, Sonja B Hofer, Thomas D Mrsicflogel
    Abstract:

    The strength of synaptic connections fundamentally determines how neurons influence each other's firing. Excitatory connection amplitudes between pairs of cortical neurons vary over two orders of magnitude, comprising only very few strong connections among many weaker ones. Although this highly skewed distribution of connection strengths is observed in diverse cortical areas, its functional significance remains unknown: it is not clear how connection strength relates to neuronal response properties, nor how strong and weak inputs contribute to information processing in local microcircuits. Here we reveal that the strength of connections between layer 2/3 (L2/3) pyramidal neurons in mouse primary visual cortex (V1) obeys a simple rule--the few strong connections occur between neurons with most correlated responses, while only weak connections link neurons with uncorrelated responses. Moreover, we show that strong and reciprocal connections occur between cells with similar spatial receptive field structure. Although weak connections far outnumber strong connections, each neuron receives the majority of its local excitation from a small number of strong inputs provided by the few neurons with similar responses to visual features. By dominating recurrent excitation, these infrequent yet powerful inputs disproportionately contribute to feature preference and selectivity. Therefore, our results show that the apparently complex organization of excitatory connection strength reflects the similarity of neuronal responses, and suggest that rare, strong connections mediate stimulus-specific response amplification in cortical microcircuits.

  • functional organization of excitatory synaptic strength in primary visual cortex
    Nature, 2015
    Co-Authors: Lee Cossell, Maria Florencia Iacaruso, Dylan R Muir, Rachael Houlton, Elie Sader, Ho Ko, Sonja B Hofer
    Abstract:

    In complex networks of the cerebral cortex, the majority of connections are weak and only a minority strong, but it is not known why; here the authors show that excitatory neurons in primary visual cortex follow a rule by which strong connections are sparse and occur between neurons with correlated responses to visual stimuli, whereas only weak connections link neurons with uncorrelated responses. The degree to which a neuron influences the activity of others is dependent on the strength of the synaptic connections it makes with its partners, and it is known that this connection strength can vary over two orders of magnitude. Using a combination of two-photon calcium imaging and simultaneous intracellular recordings from pairs of neurons, Thomas Mrsic-Flogel and colleagues show that layer 2/3 neurons in mouse primary visual cortex (V1) follow a simple rule: strong connections are sparse and occur between neurons with correlated responses to visual stimuli, whereas only weak connections link neurons with uncorrelated responses. This bias in functional connection strength may be a means by which neuronal selectivity for visual features is computed in areas downstream of V1. The strength of synaptic connections fundamentally determines how neurons influence each other’s firing. Excitatory connection amplitudes between pairs of cortical neurons vary over two orders of magnitude, comprising only very few strong connections among many weaker ones1,2,3,4,5,6,7,8,9. Although this highly skewed distribution of connection strengths is observed in diverse cortical areas1,2,3,4,5,6,7,8,9, its functional significance remains unknown: it is not clear how connection strength relates to neuronal response properties, nor how strong and weak inputs contribute to information processing in local microcircuits. Here we reveal that the strength of connections between layer 2/3 (L2/3) pyramidal neurons in mouse primary visual cortex (V1) obeys a simple rule—the few strong connections occur between neurons with most correlated responses, while only weak connections link neurons with uncorrelated responses. Moreover, we show that strong and reciprocal connections occur between cells with similar spatial receptive field structure. Although weak connections far outnumber strong connections, each neuron receives the majority of its local excitation from a small number of strong inputs provided by the few neurons with similar responses to visual features. By dominating recurrent excitation, these infrequent yet powerful inputs disproportionately contribute to feature preference and selectivity. Therefore, our results show that the apparently complex organization of excitatory connection strength reflects the similarity of neuronal responses, and suggest that rare, strong connections mediate stimulus-specific response amplification in cortical microcircuits.

Sonja B Hofer - One of the best experts on this subject based on the ideXlab platform.

  • functional organization of excitatory synaptic strength in primary visual cortex
    Nature, 2015
    Co-Authors: Lee Cossell, Maria Florencia Iacaruso, Dylan R Muir, Rachael Houlton, Elie Sader, Sonja B Hofer, Thomas D Mrsicflogel
    Abstract:

    The strength of synaptic connections fundamentally determines how neurons influence each other's firing. Excitatory connection amplitudes between pairs of cortical neurons vary over two orders of magnitude, comprising only very few strong connections among many weaker ones. Although this highly skewed distribution of connection strengths is observed in diverse cortical areas, its functional significance remains unknown: it is not clear how connection strength relates to neuronal response properties, nor how strong and weak inputs contribute to information processing in local microcircuits. Here we reveal that the strength of connections between layer 2/3 (L2/3) pyramidal neurons in mouse primary visual cortex (V1) obeys a simple rule--the few strong connections occur between neurons with most correlated responses, while only weak connections link neurons with uncorrelated responses. Moreover, we show that strong and reciprocal connections occur between cells with similar spatial receptive field structure. Although weak connections far outnumber strong connections, each neuron receives the majority of its local excitation from a small number of strong inputs provided by the few neurons with similar responses to visual features. By dominating recurrent excitation, these infrequent yet powerful inputs disproportionately contribute to feature preference and selectivity. Therefore, our results show that the apparently complex organization of excitatory connection strength reflects the similarity of neuronal responses, and suggest that rare, strong connections mediate stimulus-specific response amplification in cortical microcircuits.

  • functional organization of excitatory synaptic strength in primary visual cortex
    Nature, 2015
    Co-Authors: Lee Cossell, Maria Florencia Iacaruso, Dylan R Muir, Rachael Houlton, Elie Sader, Ho Ko, Sonja B Hofer
    Abstract:

    In complex networks of the cerebral cortex, the majority of connections are weak and only a minority strong, but it is not known why; here the authors show that excitatory neurons in primary visual cortex follow a rule by which strong connections are sparse and occur between neurons with correlated responses to visual stimuli, whereas only weak connections link neurons with uncorrelated responses. The degree to which a neuron influences the activity of others is dependent on the strength of the synaptic connections it makes with its partners, and it is known that this connection strength can vary over two orders of magnitude. Using a combination of two-photon calcium imaging and simultaneous intracellular recordings from pairs of neurons, Thomas Mrsic-Flogel and colleagues show that layer 2/3 neurons in mouse primary visual cortex (V1) follow a simple rule: strong connections are sparse and occur between neurons with correlated responses to visual stimuli, whereas only weak connections link neurons with uncorrelated responses. This bias in functional connection strength may be a means by which neuronal selectivity for visual features is computed in areas downstream of V1. The strength of synaptic connections fundamentally determines how neurons influence each other’s firing. Excitatory connection amplitudes between pairs of cortical neurons vary over two orders of magnitude, comprising only very few strong connections among many weaker ones1,2,3,4,5,6,7,8,9. Although this highly skewed distribution of connection strengths is observed in diverse cortical areas1,2,3,4,5,6,7,8,9, its functional significance remains unknown: it is not clear how connection strength relates to neuronal response properties, nor how strong and weak inputs contribute to information processing in local microcircuits. Here we reveal that the strength of connections between layer 2/3 (L2/3) pyramidal neurons in mouse primary visual cortex (V1) obeys a simple rule—the few strong connections occur between neurons with most correlated responses, while only weak connections link neurons with uncorrelated responses. Moreover, we show that strong and reciprocal connections occur between cells with similar spatial receptive field structure. Although weak connections far outnumber strong connections, each neuron receives the majority of its local excitation from a small number of strong inputs provided by the few neurons with similar responses to visual features. By dominating recurrent excitation, these infrequent yet powerful inputs disproportionately contribute to feature preference and selectivity. Therefore, our results show that the apparently complex organization of excitatory connection strength reflects the similarity of neuronal responses, and suggest that rare, strong connections mediate stimulus-specific response amplification in cortical microcircuits.

Maria Florencia Iacaruso - One of the best experts on this subject based on the ideXlab platform.

  • functional organization of excitatory synaptic strength in primary visual cortex
    Nature, 2015
    Co-Authors: Lee Cossell, Maria Florencia Iacaruso, Dylan R Muir, Rachael Houlton, Elie Sader, Sonja B Hofer, Thomas D Mrsicflogel
    Abstract:

    The strength of synaptic connections fundamentally determines how neurons influence each other's firing. Excitatory connection amplitudes between pairs of cortical neurons vary over two orders of magnitude, comprising only very few strong connections among many weaker ones. Although this highly skewed distribution of connection strengths is observed in diverse cortical areas, its functional significance remains unknown: it is not clear how connection strength relates to neuronal response properties, nor how strong and weak inputs contribute to information processing in local microcircuits. Here we reveal that the strength of connections between layer 2/3 (L2/3) pyramidal neurons in mouse primary visual cortex (V1) obeys a simple rule--the few strong connections occur between neurons with most correlated responses, while only weak connections link neurons with uncorrelated responses. Moreover, we show that strong and reciprocal connections occur between cells with similar spatial receptive field structure. Although weak connections far outnumber strong connections, each neuron receives the majority of its local excitation from a small number of strong inputs provided by the few neurons with similar responses to visual features. By dominating recurrent excitation, these infrequent yet powerful inputs disproportionately contribute to feature preference and selectivity. Therefore, our results show that the apparently complex organization of excitatory connection strength reflects the similarity of neuronal responses, and suggest that rare, strong connections mediate stimulus-specific response amplification in cortical microcircuits.

  • functional organization of excitatory synaptic strength in primary visual cortex
    Nature, 2015
    Co-Authors: Lee Cossell, Maria Florencia Iacaruso, Dylan R Muir, Rachael Houlton, Elie Sader, Ho Ko, Sonja B Hofer
    Abstract:

    In complex networks of the cerebral cortex, the majority of connections are weak and only a minority strong, but it is not known why; here the authors show that excitatory neurons in primary visual cortex follow a rule by which strong connections are sparse and occur between neurons with correlated responses to visual stimuli, whereas only weak connections link neurons with uncorrelated responses. The degree to which a neuron influences the activity of others is dependent on the strength of the synaptic connections it makes with its partners, and it is known that this connection strength can vary over two orders of magnitude. Using a combination of two-photon calcium imaging and simultaneous intracellular recordings from pairs of neurons, Thomas Mrsic-Flogel and colleagues show that layer 2/3 neurons in mouse primary visual cortex (V1) follow a simple rule: strong connections are sparse and occur between neurons with correlated responses to visual stimuli, whereas only weak connections link neurons with uncorrelated responses. This bias in functional connection strength may be a means by which neuronal selectivity for visual features is computed in areas downstream of V1. The strength of synaptic connections fundamentally determines how neurons influence each other’s firing. Excitatory connection amplitudes between pairs of cortical neurons vary over two orders of magnitude, comprising only very few strong connections among many weaker ones1,2,3,4,5,6,7,8,9. Although this highly skewed distribution of connection strengths is observed in diverse cortical areas1,2,3,4,5,6,7,8,9, its functional significance remains unknown: it is not clear how connection strength relates to neuronal response properties, nor how strong and weak inputs contribute to information processing in local microcircuits. Here we reveal that the strength of connections between layer 2/3 (L2/3) pyramidal neurons in mouse primary visual cortex (V1) obeys a simple rule—the few strong connections occur between neurons with most correlated responses, while only weak connections link neurons with uncorrelated responses. Moreover, we show that strong and reciprocal connections occur between cells with similar spatial receptive field structure. Although weak connections far outnumber strong connections, each neuron receives the majority of its local excitation from a small number of strong inputs provided by the few neurons with similar responses to visual features. By dominating recurrent excitation, these infrequent yet powerful inputs disproportionately contribute to feature preference and selectivity. Therefore, our results show that the apparently complex organization of excitatory connection strength reflects the similarity of neuronal responses, and suggest that rare, strong connections mediate stimulus-specific response amplification in cortical microcircuits.

Charles W Roeder - One of the best experts on this subject based on the ideXlab platform.

  • seismic design of circular concrete filled tube bridge pier connections for accelerated bridge construction
    Structures Congress 2014American Society of Civil Engineers, 2014
    Co-Authors: Max Stephens, Lisa M Berg, Dawn E Lehman, Charles W Roeder
    Abstract:

    Concrete-filled tubes (CFT) offer an efficient and economical alternative to conventional reinforced concrete construction; however, their implementation in the United States (US) has been limited mainly due to uncertain design expressions and reliable connections. A research program was undertaken at the University of Washington to develop connection details to use CFT columns in bridge systems. Two types of connections are being investigated, including column-to-foundation and integrated column-to-cap beam connections. Two variations of an embedded CFT-to-foundation connection were experimentally evaluated in which the steel tube was embedded in surrounding concrete. Results from the experimental studies were used to develop engineering expressions for design of the CFT column-to-foundation connection. The second phase of the study focuses on the column-to-cap beam connection which offers many unique design constraints including congested joint reinforcing and limits on geometry. Two variations of the CFT column-to-cap beam connection are being numerically and experimentally evaluated: (1) an embedded connection similar to the proposed foundation connection and (2) a connection in which headed reinforcing bars are welded to the inside of the steel tube and extended into the cap beam. Preliminary numerical and experimental results indicate that the embedded connection can achieve strength and ductility requirements within the constraints of the cap beam.

  • connection performance for seismic design of steel moment frames
    Journal of Structural Engineering-asce, 2002
    Co-Authors: Charles W Roeder
    Abstract:

    Welded-flange-bolted-web connections were damaged during the Northridge Earthquake, and the SAC Steel Project was started to find solutions to the problems caused by this damage. The Connection Performance Team was one of several groups completing the project research, and this group examined all connection performance issues. A number of connections were evaluated, and three strategies were used to improve the seismic performance of different connections. An understanding of all yield mechanisms and failure modes for each connection type is required for applicaiton of these improvement strategies. Variations in yield mechanisms and failure modes obtained for different connection types are described, and the application of these modes and mechanisms to improve the seismic performance of three different connections is summarized. The three connections are the welded-flange-welded-web, reduced-beam-seciton, and bolted-flange-plate connections. These connections are all capable of providing good seismic performance with large plastic rotational capacity, but each connection requires evaluation of different modes and mechanisms and different balance requirements for good seismic performance. The strategies and procedures used for these connections are typical of those used for many other connections.

Ho Ko - One of the best experts on this subject based on the ideXlab platform.

  • functional organization of excitatory synaptic strength in primary visual cortex
    Nature, 2015
    Co-Authors: Lee Cossell, Maria Florencia Iacaruso, Dylan R Muir, Rachael Houlton, Elie Sader, Ho Ko, Sonja B Hofer
    Abstract:

    In complex networks of the cerebral cortex, the majority of connections are weak and only a minority strong, but it is not known why; here the authors show that excitatory neurons in primary visual cortex follow a rule by which strong connections are sparse and occur between neurons with correlated responses to visual stimuli, whereas only weak connections link neurons with uncorrelated responses. The degree to which a neuron influences the activity of others is dependent on the strength of the synaptic connections it makes with its partners, and it is known that this connection strength can vary over two orders of magnitude. Using a combination of two-photon calcium imaging and simultaneous intracellular recordings from pairs of neurons, Thomas Mrsic-Flogel and colleagues show that layer 2/3 neurons in mouse primary visual cortex (V1) follow a simple rule: strong connections are sparse and occur between neurons with correlated responses to visual stimuli, whereas only weak connections link neurons with uncorrelated responses. This bias in functional connection strength may be a means by which neuronal selectivity for visual features is computed in areas downstream of V1. The strength of synaptic connections fundamentally determines how neurons influence each other’s firing. Excitatory connection amplitudes between pairs of cortical neurons vary over two orders of magnitude, comprising only very few strong connections among many weaker ones1,2,3,4,5,6,7,8,9. Although this highly skewed distribution of connection strengths is observed in diverse cortical areas1,2,3,4,5,6,7,8,9, its functional significance remains unknown: it is not clear how connection strength relates to neuronal response properties, nor how strong and weak inputs contribute to information processing in local microcircuits. Here we reveal that the strength of connections between layer 2/3 (L2/3) pyramidal neurons in mouse primary visual cortex (V1) obeys a simple rule—the few strong connections occur between neurons with most correlated responses, while only weak connections link neurons with uncorrelated responses. Moreover, we show that strong and reciprocal connections occur between cells with similar spatial receptive field structure. Although weak connections far outnumber strong connections, each neuron receives the majority of its local excitation from a small number of strong inputs provided by the few neurons with similar responses to visual features. By dominating recurrent excitation, these infrequent yet powerful inputs disproportionately contribute to feature preference and selectivity. Therefore, our results show that the apparently complex organization of excitatory connection strength reflects the similarity of neuronal responses, and suggest that rare, strong connections mediate stimulus-specific response amplification in cortical microcircuits.