The Experts below are selected from a list of 1440 Experts worldwide ranked by ideXlab platform
Jeffrey C Magee - One of the best experts on this subject based on the ideXlab platform.
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Active Dendritic Integration and mixed neocortical network representations during an adaptive sensing behavior.
Nature neuroscience, 2018Co-Authors: Gayathri Nattar Ranganathan, Mark T Harnett, Pierre F. Apostolides, Shaul Druckmann, Jeffrey C MageeAbstract:Animals strategically scan the environment to form an accurate perception of their surroundings. Here we investigated the neuronal representations that mediate this behavior. Ca2+ imaging and selective optogenetic manipulation during an active sensing task reveals that layer 5 pyramidal neurons in the vibrissae cortex produce a diverse and distributed representation that is required for mice to adapt their whisking motor strategy to changing sensory cues. The optogenetic perturbation degraded single-neuron selectivity and network population encoding through a selective inhibition of active Dendritic Integration. Together the data indicate that active Dendritic Integration in pyramidal neurons produces a nonlinearly mixed network representation of joint sensorimotor parameters that is used to transform sensory information into motor commands during adaptive behavior. The prevalence of the layer 5 cortical circuit motif suggests that this is a general circuit computation.
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Variable Dendritic Integration in Hippocampal CA3 Pyramidal Neurons
Neuron, 2013Co-Authors: Judit K. Makara, Jeffrey C MageeAbstract:The hippocampal CA3 region is essential for pattern completion and generation of sharp-wave ripples. During these operations, coordinated activation of ensembles of CA3 pyramidal neurons produces spatiotemporally structured input patterns arriving onto dendrites of recurrently connected CA3 neurons. To understand how such input patterns are translated into specific output patterns, we characterized Dendritic Integration in CA3 pyramidal cells using two-photon imaging and glutamate uncaging. We found that thin dendrites of CA3 pyramidal neurons integrate synchronous synaptic input in a highly supralinear fashion. The amplification was primarily mediated by NMDA receptor activation and was present over a relatively broad range of spatiotemporal input patterns. The decay of voltage responses, temporal summation, and action potential output was regulated in a compartmentalized fashion mainly by a G-protein-activated inwardly rectifying K+ current. Our results suggest that plastic Dendritic integrative mechanisms may support ensemble behavior in pyramidal neurons of the hippocampal circuitry.
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Potassium Channels Control the Interaction between Active Dendritic Integration Compartments in Layer 5 Cortical Pyramidal Neurons
Neuron, 2013Co-Authors: Mark T Harnett, Jeffrey C Magee, Stephen R WilliamsAbstract:Active Dendritic synaptic Integration enhances the computational power of neurons. Such nonlinear processing generates an object-localization signal in the apical Dendritic tuft of layer 5B cortical pyramidal neurons during sensory-motor behavior. Here, we employ electrophysiological and optical approaches in brain slices and behaving animals to investigate how excitatory synaptic input to this distal Dendritic compartment influences neuronal output. We find that active Dendritic Integration throughout the apical Dendritic tuft is highly compartmentalized by voltage-gated potassium (KV) channels. A high density of both transient and sustained KV channels was observed in all apical Dendritic compartments. These channels potently regulated the interaction between apical Dendritic tuft, trunk, and axosomatic Integration zones to control neuronal output in vitro as well as the engagement of Dendritic nonlinear processing in vivo during sensory-motor behavior. Thus, KV channels dynamically tune the interaction between active Dendritic Integration compartments in layer 5B pyramidal neurons to shape behaviorally relevant neuronal computations.
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nonlinear Dendritic Integration of sensory and motor input during an active sensing task
Nature, 2012Co-Authors: Ninglong Xu, Mark T Harnett, Stephen R Williams, Daniel Huber, Daniel H Oconnor, Karel Svoboda, Jeffrey C MageeAbstract:Recordings from cortical neuron dendrites of head-fixed mice during an object-localization task provide direct evidence that a novel global nonlinearity has a role in integrating sensory and motor information during a behaviour-related computation. Neuronal dendrites, the branch-like projections on nerve cells, are increasingly seen as more than just passive integrators of synaptic inputs, but whether their nonlinear electrical properties have a role in vivo has remained unclear. Now Jeffrey Magee and colleagues have recorded from cortical neuron dendrites from mice engaged in object localization using rhythmic whisker movements known as whisking, and show that sensory-evoked Dendritic activity is dependent on input from the adjacent motor cortex. The results demonstrate that active nonlinear Dendritic Integration in cortical neurons is central to the production of a behaviour-related computation — the Integration of sensory and motor information. Active dendrites provide neurons with powerful processing capabilities. However, little is known about the role of neuronal dendrites in behaviourally related circuit computations. Here we report that a novel global Dendritic nonlinearity is involved in the Integration of sensory and motor information within layer 5 pyramidal neurons during an active sensing behaviour. Layer 5 pyramidal neurons possess elaborate Dendritic arborizations that receive functionally distinct inputs, each targeted to spatially separate regions1,2. At the cellular level, coincident input from these segregated pathways initiates regenerative Dendritic electrical events that produce bursts of action potential output3,4 and circuits featuring this powerful Dendritic nonlinearity can implement computations based on input correlation5. To examine this in vivo we recorded Dendritic activity in layer 5 pyramidal neurons in the barrel cortex using two-photon calcium imaging in mice performing an object-localization task. Large-amplitude, global calcium signals were observed throughout the apical tuft dendrites when active touch occurred at particular object locations or whisker angles. Such global calcium signals are produced by Dendritic plateau potentials that require both vibrissal sensory input and primary motor cortex activity. These data provide direct evidence of nonlinear Dendritic processing of correlated sensory and motor information in the mammalian neocortex during active sensation.
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Nonlinear Dendritic Integration of sensory and motor input during an active sensing task
Nature, 2012Co-Authors: Mark T Harnett, Stephen R Williams, Daniel Huber, Karel Svoboda, Daniel T. O'connor, Jeffrey C MageeAbstract:Active dendrites provide neurons with powerful processing capabilities. However, little is known about the role of neuronal dendrites in behaviourally related circuit computations. Here we report that a novel global Dendritic nonlinearity is involved in the Integration of sensory and motor information within layer 5 pyramidal neurons during an active sensing behaviour. Layer 5 pyramidal neurons possess elaborate Dendritic arborizations that receive functionally distinct inputs, each targeted to spatially separate regions. At the cellular level, coincident input from these segregated pathways initiates regenerative Dendritic electrical events that produce bursts of action potential output and circuits featuring this powerful Dendritic nonlinearity can implement computations based on input correlation. To examine this in vivo we recorded Dendritic activity in layer 5 pyramidal neurons in the barrel cortex using two-photon calcium imaging in mice performing an object-localization task. Large-amplitude, global calcium signals were observed throughout the apical tuft dendrites when active touch occurred at particular object locations or whisker angles. Such global calcium signals are produced by Dendritic plateau potentials that require both vibrissal sensory input and primary motor cortex activity. These data provide direct evidence of nonlinear Dendritic processing of correlated sensory and motor information in the mammalian neocortex during active sensation.
Stephen R Williams - One of the best experts on this subject based on the ideXlab platform.
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A Dendritic Substrate for the Cholinergic Control of Neocortical Output Neurons.
Neuron, 2019Co-Authors: Stephen R Williams, Lee N. FletcherAbstract:The ascending cholinergic system dynamically regulates sensory perception and cognitive function, but it remains unclear how this modulation is executed in neocortical circuits. Here, we demonstrate that the cholinergic system controls the integrative operations of neocortical principal neurons by modulating Dendritic excitability. Direct Dendritic recordings revealed that the optogenetic-evoked release of acetylcholine (ACh) transformed the pattern of Dendritic Integration in layer 5B pyramidal neurons, leading to the generation of Dendritic plateau potentials which powerfully drove repetitive action potential output. In contrast, the synaptic release of ACh did not positively modulate axo-somatic excitability. Mechanistically, the transformation of Dendritic Integration was mediated by the muscarinic ACh receptor-dependent enhancement of Dendritic R-type calcium channel activity, a compartment-dependent modulation which decisively controlled the associative computations executed by layer 5B pyramidal neurons. Our findings therefore reveal a biophysical mechanism by which the cholinergic system controls Dendritic computations causally linked to perceptual detection.
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Direction selectivity is computed by active Dendritic Integration in retinal ganglion cells
Nature neuroscience, 2013Co-Authors: Benjamin Sivyer, Stephen R WilliamsAbstract:Active Dendritic Integration is thought to enrich the computational power of central neurons. However, a direct role of active Dendritic processing in the execution of defined neuronal computations in intact neural networks has not been established. Here we used multi-site electrophysiological recording techniques to demonstrate that active Dendritic Integration underlies the computation of direction selectivity in rabbit retinal ganglion cells. Direction-selective retinal ganglion cells fire action potentials in response to visual image movement in a preferred direction. Dendritic recordings revealed that preferred-direction moving-light stimuli led to Dendritic spike generation in terminal dendrites, which were further integrated and amplified as they spread through the Dendritic arbor to the axon to drive action potential output. In contrast, when light bars moved in a null direction, synaptic inhibition vetoed neuronal output by directly inhibiting terminal Dendritic spike initiation. Active Dendritic Integration therefore underlies a physiologically engaged circuit-based computation in the retina.
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Potassium Channels Control the Interaction between Active Dendritic Integration Compartments in Layer 5 Cortical Pyramidal Neurons
Neuron, 2013Co-Authors: Mark T Harnett, Jeffrey C Magee, Stephen R WilliamsAbstract:Active Dendritic synaptic Integration enhances the computational power of neurons. Such nonlinear processing generates an object-localization signal in the apical Dendritic tuft of layer 5B cortical pyramidal neurons during sensory-motor behavior. Here, we employ electrophysiological and optical approaches in brain slices and behaving animals to investigate how excitatory synaptic input to this distal Dendritic compartment influences neuronal output. We find that active Dendritic Integration throughout the apical Dendritic tuft is highly compartmentalized by voltage-gated potassium (KV) channels. A high density of both transient and sustained KV channels was observed in all apical Dendritic compartments. These channels potently regulated the interaction between apical Dendritic tuft, trunk, and axosomatic Integration zones to control neuronal output in vitro as well as the engagement of Dendritic nonlinear processing in vivo during sensory-motor behavior. Thus, KV channels dynamically tune the interaction between active Dendritic Integration compartments in layer 5B pyramidal neurons to shape behaviorally relevant neuronal computations.
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nonlinear Dendritic Integration of sensory and motor input during an active sensing task
Nature, 2012Co-Authors: Ninglong Xu, Mark T Harnett, Stephen R Williams, Daniel Huber, Daniel H Oconnor, Karel Svoboda, Jeffrey C MageeAbstract:Recordings from cortical neuron dendrites of head-fixed mice during an object-localization task provide direct evidence that a novel global nonlinearity has a role in integrating sensory and motor information during a behaviour-related computation. Neuronal dendrites, the branch-like projections on nerve cells, are increasingly seen as more than just passive integrators of synaptic inputs, but whether their nonlinear electrical properties have a role in vivo has remained unclear. Now Jeffrey Magee and colleagues have recorded from cortical neuron dendrites from mice engaged in object localization using rhythmic whisker movements known as whisking, and show that sensory-evoked Dendritic activity is dependent on input from the adjacent motor cortex. The results demonstrate that active nonlinear Dendritic Integration in cortical neurons is central to the production of a behaviour-related computation — the Integration of sensory and motor information. Active dendrites provide neurons with powerful processing capabilities. However, little is known about the role of neuronal dendrites in behaviourally related circuit computations. Here we report that a novel global Dendritic nonlinearity is involved in the Integration of sensory and motor information within layer 5 pyramidal neurons during an active sensing behaviour. Layer 5 pyramidal neurons possess elaborate Dendritic arborizations that receive functionally distinct inputs, each targeted to spatially separate regions1,2. At the cellular level, coincident input from these segregated pathways initiates regenerative Dendritic electrical events that produce bursts of action potential output3,4 and circuits featuring this powerful Dendritic nonlinearity can implement computations based on input correlation5. To examine this in vivo we recorded Dendritic activity in layer 5 pyramidal neurons in the barrel cortex using two-photon calcium imaging in mice performing an object-localization task. Large-amplitude, global calcium signals were observed throughout the apical tuft dendrites when active touch occurred at particular object locations or whisker angles. Such global calcium signals are produced by Dendritic plateau potentials that require both vibrissal sensory input and primary motor cortex activity. These data provide direct evidence of nonlinear Dendritic processing of correlated sensory and motor information in the mammalian neocortex during active sensation.
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Nonlinear Dendritic Integration of sensory and motor input during an active sensing task
Nature, 2012Co-Authors: Mark T Harnett, Stephen R Williams, Daniel Huber, Karel Svoboda, Daniel T. O'connor, Jeffrey C MageeAbstract:Active dendrites provide neurons with powerful processing capabilities. However, little is known about the role of neuronal dendrites in behaviourally related circuit computations. Here we report that a novel global Dendritic nonlinearity is involved in the Integration of sensory and motor information within layer 5 pyramidal neurons during an active sensing behaviour. Layer 5 pyramidal neurons possess elaborate Dendritic arborizations that receive functionally distinct inputs, each targeted to spatially separate regions. At the cellular level, coincident input from these segregated pathways initiates regenerative Dendritic electrical events that produce bursts of action potential output and circuits featuring this powerful Dendritic nonlinearity can implement computations based on input correlation. To examine this in vivo we recorded Dendritic activity in layer 5 pyramidal neurons in the barrel cortex using two-photon calcium imaging in mice performing an object-localization task. Large-amplitude, global calcium signals were observed throughout the apical tuft dendrites when active touch occurred at particular object locations or whisker angles. Such global calcium signals are produced by Dendritic plateau potentials that require both vibrissal sensory input and primary motor cortex activity. These data provide direct evidence of nonlinear Dendritic processing of correlated sensory and motor information in the mammalian neocortex during active sensation.
Mu-ming Poo - One of the best experts on this subject based on the ideXlab platform.
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Spike Timing-Dependent Plasticity: From Synapse to Perception
Physiological reviews, 2006Co-Authors: Yang Dan, Mu-ming PooAbstract:Information in the nervous system may be carried by both the rate and timing of neuronal spikes. Recent findings of spike timing-dependent plasticity (STDP) have fueled the interest in the potential roles of spike timing in processing and storage of information in neural circuits. Induction of long-term potentiation (LTP) and long-term depression (LTD) in a variety of in vitro and in vivo systems has been shown to depend on the temporal order of pre- and postsynaptic spiking. Spike timing-dependent modification of neuronal excitability and Dendritic Integration was also observed. Such STDP at the synaptic and cellular level is likely to play important roles in activity-induced functional changes in neuronal receptive fields and human perception.
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Spike Timing-Dependent Plasticity of Neural Circuits
Neuron, 2004Co-Authors: Yang Dan, Mu-ming PooAbstract:Recent findings of spike timing-dependent plasticity (STDP) have stimulated much interest among experimentalists and theorists. Beyond the traditional correlation-based Hebbian plasticity, STDP opens up new avenues for understanding information coding and circuit plasticity that depend on the precise timing of neuronal spikes. Here we summarize experimental characterization of STDP at various synapses, the underlying cellular mechanisms, and the associated changes in neuronal excitability and Dendritic Integration. We also describe STDP in the context of complex spike patterns and its dependence on the Dendritic location of the synapse. Finally, we discuss timing-dependent modification of neuronal receptive fields and human visual perception and the computational significance of STDP as a synaptic learning rule.
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Bidirectional Changes in Spatial Dendritic Integration Accompanying Long-Term Synaptic Modifications
Neuron, 2003Co-Authors: Zhiru Wang, Shumin Duan, Mu-ming PooAbstract:Information processing in the neuron requires spatial summation of synaptic inputs at the dendrite. In CA1 pyramidal neurons of the hippocampus, a brief period of correlated pre- and postsynaptic activity, which induces long-term potentiation (LTP) or long-term depression (LTD), results in a persistent increase or decrease in the linearity of spatial summation, respectively. Such bidirectional modification of the summation property is specific to the modified input and reflects localized Dendritic changes involving I(h) channels and NMDA receptors. Thus, correlated pre- and postsynaptic activity alters not only the strength of the activated input but also its Dendritic Integration with other inputs.
Mark T Harnett - One of the best experts on this subject based on the ideXlab platform.
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Widespread and Highly Correlated Somato-Dendritic Activity in Cortical Layer 5 Neurons
Neuron, 2019Co-Authors: Lou Beaulieu-laroche, Enrique H.s. Toloza, Norma J. Brown, Mark T HarnettAbstract:Dendritic Integration can expand the information-processing capabilities of neurons. However, the recruitment of active Dendritic processing in vivo and its relationship to somatic activity remain poorly understood. Here, we use two-photon GCaMP6f imaging to simultaneously monitor Dendritic and somatic compartments in the awake primary visual cortex. Activity in layer 5 pyramidal neuron somata and distal apical trunk dendrites shows surprisingly high functional correlation. This strong coupling persists across neural activity levels and is unchanged by visual stimuli and locomotion. Ex vivo combined somato-Dendritic patch-clamp and GCaMP6f recordings indicate that Dendritic signals specifically reflect local electrogenesis triggered by Dendritic inputs or high-frequency bursts of somatic action potentials. In contrast to the view that dendrites are only sparsely recruited under highly specific conditions in vivo, our results provide evidence that active Dendritic Integration is a widespread and intrinsic feature of cortical computation.
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Active Dendritic Integration and mixed neocortical network representations during an adaptive sensing behavior.
Nature neuroscience, 2018Co-Authors: Gayathri Nattar Ranganathan, Mark T Harnett, Pierre F. Apostolides, Shaul Druckmann, Jeffrey C MageeAbstract:Animals strategically scan the environment to form an accurate perception of their surroundings. Here we investigated the neuronal representations that mediate this behavior. Ca2+ imaging and selective optogenetic manipulation during an active sensing task reveals that layer 5 pyramidal neurons in the vibrissae cortex produce a diverse and distributed representation that is required for mice to adapt their whisking motor strategy to changing sensory cues. The optogenetic perturbation degraded single-neuron selectivity and network population encoding through a selective inhibition of active Dendritic Integration. Together the data indicate that active Dendritic Integration in pyramidal neurons produces a nonlinearly mixed network representation of joint sensorimotor parameters that is used to transform sensory information into motor commands during adaptive behavior. The prevalence of the layer 5 cortical circuit motif suggests that this is a general circuit computation.
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Potassium Channels Control the Interaction between Active Dendritic Integration Compartments in Layer 5 Cortical Pyramidal Neurons
Neuron, 2013Co-Authors: Mark T Harnett, Jeffrey C Magee, Stephen R WilliamsAbstract:Active Dendritic synaptic Integration enhances the computational power of neurons. Such nonlinear processing generates an object-localization signal in the apical Dendritic tuft of layer 5B cortical pyramidal neurons during sensory-motor behavior. Here, we employ electrophysiological and optical approaches in brain slices and behaving animals to investigate how excitatory synaptic input to this distal Dendritic compartment influences neuronal output. We find that active Dendritic Integration throughout the apical Dendritic tuft is highly compartmentalized by voltage-gated potassium (KV) channels. A high density of both transient and sustained KV channels was observed in all apical Dendritic compartments. These channels potently regulated the interaction between apical Dendritic tuft, trunk, and axosomatic Integration zones to control neuronal output in vitro as well as the engagement of Dendritic nonlinear processing in vivo during sensory-motor behavior. Thus, KV channels dynamically tune the interaction between active Dendritic Integration compartments in layer 5B pyramidal neurons to shape behaviorally relevant neuronal computations.
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nonlinear Dendritic Integration of sensory and motor input during an active sensing task
Nature, 2012Co-Authors: Ninglong Xu, Mark T Harnett, Stephen R Williams, Daniel Huber, Daniel H Oconnor, Karel Svoboda, Jeffrey C MageeAbstract:Recordings from cortical neuron dendrites of head-fixed mice during an object-localization task provide direct evidence that a novel global nonlinearity has a role in integrating sensory and motor information during a behaviour-related computation. Neuronal dendrites, the branch-like projections on nerve cells, are increasingly seen as more than just passive integrators of synaptic inputs, but whether their nonlinear electrical properties have a role in vivo has remained unclear. Now Jeffrey Magee and colleagues have recorded from cortical neuron dendrites from mice engaged in object localization using rhythmic whisker movements known as whisking, and show that sensory-evoked Dendritic activity is dependent on input from the adjacent motor cortex. The results demonstrate that active nonlinear Dendritic Integration in cortical neurons is central to the production of a behaviour-related computation — the Integration of sensory and motor information. Active dendrites provide neurons with powerful processing capabilities. However, little is known about the role of neuronal dendrites in behaviourally related circuit computations. Here we report that a novel global Dendritic nonlinearity is involved in the Integration of sensory and motor information within layer 5 pyramidal neurons during an active sensing behaviour. Layer 5 pyramidal neurons possess elaborate Dendritic arborizations that receive functionally distinct inputs, each targeted to spatially separate regions1,2. At the cellular level, coincident input from these segregated pathways initiates regenerative Dendritic electrical events that produce bursts of action potential output3,4 and circuits featuring this powerful Dendritic nonlinearity can implement computations based on input correlation5. To examine this in vivo we recorded Dendritic activity in layer 5 pyramidal neurons in the barrel cortex using two-photon calcium imaging in mice performing an object-localization task. Large-amplitude, global calcium signals were observed throughout the apical tuft dendrites when active touch occurred at particular object locations or whisker angles. Such global calcium signals are produced by Dendritic plateau potentials that require both vibrissal sensory input and primary motor cortex activity. These data provide direct evidence of nonlinear Dendritic processing of correlated sensory and motor information in the mammalian neocortex during active sensation.
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Nonlinear Dendritic Integration of sensory and motor input during an active sensing task
Nature, 2012Co-Authors: Mark T Harnett, Stephen R Williams, Daniel Huber, Karel Svoboda, Daniel T. O'connor, Jeffrey C MageeAbstract:Active dendrites provide neurons with powerful processing capabilities. However, little is known about the role of neuronal dendrites in behaviourally related circuit computations. Here we report that a novel global Dendritic nonlinearity is involved in the Integration of sensory and motor information within layer 5 pyramidal neurons during an active sensing behaviour. Layer 5 pyramidal neurons possess elaborate Dendritic arborizations that receive functionally distinct inputs, each targeted to spatially separate regions. At the cellular level, coincident input from these segregated pathways initiates regenerative Dendritic electrical events that produce bursts of action potential output and circuits featuring this powerful Dendritic nonlinearity can implement computations based on input correlation. To examine this in vivo we recorded Dendritic activity in layer 5 pyramidal neurons in the barrel cortex using two-photon calcium imaging in mice performing an object-localization task. Large-amplitude, global calcium signals were observed throughout the apical tuft dendrites when active touch occurred at particular object locations or whisker angles. Such global calcium signals are produced by Dendritic plateau potentials that require both vibrissal sensory input and primary motor cortex activity. These data provide direct evidence of nonlinear Dendritic processing of correlated sensory and motor information in the mammalian neocortex during active sensation.
Alain Destexhe - One of the best experts on this subject based on the ideXlab platform.
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noisy dendrites models of Dendritic Integration in vivo
2014Co-Authors: Alain Destexhe, Michelle RudolphlilithAbstract:While Dendritic processing has been well characterized in vitro, there is little experimental data and models available about the integrative properties of dendrites in vivo. Here, we review existing computational models to infer the Dendritic processing of neocortical pyramidal neurons in vivo. We start by summarizing experimental measurements of the “high-conductance states” of cortical neurons in vivo. Next, we show models predicting that, in such states, the responsiveness of cortical neurons should be greatly enhanced, in particular due to the presence of high-amplitude fluctuations (“synaptic noise”). We infer that in dendrites this effect should be particularly strong, leading to the spontaneous activation of Dendritic spikes. The presence of noise in dendrites also enhances spike propagation. We show that opposite distance dependencies of spike initiation and propagation result in roughly location-independent synaptic efficacies. In addition, in high-conductance states, dendrites display sharper temporal processing capabilities. Thus, we conclude that noisy active dendrites behave more “democratically,” and that dendrites should have enhanced processing capabilities in vivo.
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Location independence and fast conduction of synaptic inputs in neocortical neurons in vivo
Neurocomputing, 2003Co-Authors: Alain Destexhe, Michael RudolphAbstract:Neocortical neurons in vivo operate in a high-conductance state characterized by an intense intracellular fluctuating activity. Here we investigate how these conditions impact on the Dendritic Integration of synaptic inputs by using biophysical models of morphologically reconstructed neocortical pyramidal neurons. We find that the combined effect of high conductance and fluctuating activity due to the synaptic background activity may set pyramidal neurons into an integrative mode which is determined by the intensity of network activity, which is fast-conducting and in which the impact of inputs is roughly location-independent
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Novel dynamics of Dendritic Integration in the high conductance state of cortical neurons
Neurocomputing, 2002Co-Authors: Michael Rudolph, Alain DestexheAbstract:Abstract Neocortical neurons in vivo operate in a high-conductance state which may affect the dynamics of Dendritic Integration, but this aspect remains only barely characterized. We investigated this problem by using biophysical models of morphologically reconstructed neocortical pyramidal neurons in which isolated and paired synaptic events were studied according to their Dendritic location. We show that during active states, there is an ongoing dynamics of randomly occurring forward- and back-propagating Dendritic action potentials. This dynamics determinantly impacts on how individual or paired synaptic events interact, leading to a type of integrative behavior which is different from classical models of Dendritic Integration.
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Novel dynamics of Dendritic Integration in the hight conductance state of cortical neurons
Neurocomputing, 2002Co-Authors: Michael Rudolph, Alain DestexheAbstract:Neocortical neurons in vivo operate in a high-conductance state which may affect the dynamics of Dendritic Integration, but this aspect remains only barely characterized. We investigated this problem by using biophysical models of morphologically reconstructed neocortical pyramidal neurons in which isolated and paired synaptic events were studied according to their Dendritic location. We show that during active states, there is an ongoing dynamics of randomly occurring forward- and back-propagating Dendritic action potentials. This dynamics determinantly impacts on how individual or paired synaptic events interact, leading to a type of integrative behavior which is different from classical models of Dendritic Integration.
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Synaptic background activity affects the dynamics of Dendritic Integration in model neocortical pyramidal neurons
Neurocomputing, 2001Co-Authors: Michael Rudolph, Alain DestexheAbstract:Neocortical pyramidal neurons in vivo are subject to an intense synaptic background activity which may significantly impact on Dendritic Integration, but this aspect is largely unexplored. Here we use computational models of morphologically-reconstructed pyramidal neurons, in which synaptic background activity was simulated according to recent measurements in cat parietal cortex. We show that background activity markedly enhances voltage attenuation, which results in a relative electrotonic “isolation” of different Dendritic segments. On the other hand, the active propagation of action potentials in dendrites is minimally affected. The consequence is that inputs are integrated locally and their impact on the soma is independent on their position in the Dendritic tree. We conclude that background activity sets up a dynamics of Dendritic Integration which is radically different compared to quiescent states