The Experts below are selected from a list of 156 Experts worldwide ranked by ideXlab platform
Rishikesh Narayanan - One of the best experts on this subject based on the ideXlab platform.
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Robust emergence of sharply tuned place cell responses in hippocampal neurons with structural and biophysical heterogeneities
bioRxiv, 2019Co-Authors: Reshma Basak, Rishikesh NarayananAbstract:Hippocampal pyramidal neurons sustain propagation of fast electrical signals and are electrotonically non-compact structures exhibiting cell-to-cell variability in their complex Dendritic arborization. In this study, we demonstrate that sharp place-field tuning and several somato-Dendritic functional maps concomitantly emerge despite the presence of geometrical heterogeneities in these neurons. We establish this employing an unbiased stochastic search strategy involving thousands of models that spanned several morphologies and distinct profiles of dispersed synaptic localization and channel expression. Mechanistically, employing virtual knockout models, we explored the impact of bidirectional modulation in Dendritic Spike prevalence on place-field tuning sharpness. Consistent with prior literature, we found that across all morphologies, virtual knockout of either Dendritic fast sodium channels or N-methyl-D-aspartate receptors led to a reduction in Dendritic Spike prevalence, whereas A-type potassium channel knockouts resulted in a nonspecific increase in Dendritic Spike prevalence. However, place-field tuning sharpness was critically impaired in all three sets of virtual knockout models, demonstrating that sharpness in feature tuning is maintained by an intricate balance between mechanisms that promote and those that prevent Dendritic Spike initiation. From the functional standpoint of the emergence of sharp feature tuning and intrinsic functional maps, within this framework, geometric variability was compensated by a combination of synaptic democracy, the ability of randomly dispersed synapses to yield sharp tuning through Dendritic Spike initiation, and ion-channel degeneracy. Our results suggest electrotonically non-compact neurons to be endowed with several degrees of freedom, encompassing channel expression, synaptic localization and morphological micro-structure, in achieving sharp feature encoding and excitability homeostasis.
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spatially dispersed synapses yield sharply tuned place cell responses through Dendritic Spike initiation
The Journal of Physiology, 2018Co-Authors: Reshma Basak, Rishikesh NarayananAbstract:A prominent hypothesis spanning several sensory-perceptual systems implicates spatially clustered synapses in the generation of Dendritic Spikes that mediate sharply-tuned neuronal responses to input features. In this conductance-based morphologically-precise computational study, we tested this hypothesis by systematically analysing the impact of distinct synaptic and channel localization profiles on sharpness of spatial tuning in hippocampal pyramidal neurons. We found that the generation of Dendritic Spikes, the emergence of an excitatory ramp in somatic voltage responses, the expression of several intrinsic somatoDendritic functional maps and sharp tuning of place-cell responses were all attainable even when iso-feature synapses are randomly dispersed across the Dendritic arbor of models with disparate channel combinations. Strikingly, the generation and propagation of Dendritic Spikes, reliant on Dendritic sodium channels and N-methyl-d-asparate receptors, mediated the sharpness of spatial tuning achieved with dispersed synaptic localization. To ensure that our results were not artefacts of narrow parametric choices, we confirmed these conclusions with independent multiparametric stochastic search algorithms spanning thousands of unique models for each synaptic localization scenario.Next, employing virtual knockout models, we demonstrated a vital role for Dendritically expressed voltage-gated ion channels, especially the transient potassium channels, in maintaining sharpness of place-cell tuning. Importantly, we established that synaptic potentiation targeted to afferents from one specific place field was sufficient to impart place field selectivity even when intrinsically disparate neurons received randomly dispersed afferents from multiple place field locations. Our results provide quantitative evidence for disparate combinations of channel and synaptic localization profiles to concomitantly yield similar tuning and similar intrinsic properties.
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Spatially dispersed synapses yield sharply‐tuned place cell responses through Dendritic Spike initiation
The Journal of Physiology, 2018Co-Authors: Reshma Basak, Rishikesh NarayananAbstract:A prominent hypothesis spanning several sensory-perceptual systems implicates spatially clustered synapses in the generation of Dendritic Spikes that mediate sharply-tuned neuronal responses to input features. In this conductance-based morphologically-precise computational study, we tested this hypothesis by systematically analysing the impact of distinct synaptic and channel localization profiles on sharpness of spatial tuning in hippocampal pyramidal neurons. We found that the generation of Dendritic Spikes, the emergence of an excitatory ramp in somatic voltage responses, the expression of several intrinsic somatoDendritic functional maps and sharp tuning of place-cell responses were all attainable even when iso-feature synapses are randomly dispersed across the Dendritic arbor of models with disparate channel combinations. Strikingly, the generation and propagation of Dendritic Spikes, reliant on Dendritic sodium channels and N-methyl-d-asparate receptors, mediated the sharpness of spatial tuning achieved with dispersed synaptic localization. To ensure that our results were not artefacts of narrow parametric choices, we confirmed these conclusions with independent multiparametric stochastic search algorithms spanning thousands of unique models for each synaptic localization scenario.Next, employing virtual knockout models, we demonstrated a vital role for Dendritically expressed voltage-gated ion channels, especially the transient potassium channels, in maintaining sharpness of place-cell tuning. Importantly, we established that synaptic potentiation targeted to afferents from one specific place field was sufficient to impart place field selectivity even when intrinsically disparate neurons received randomly dispersed afferents from multiple place field locations. Our results provide quantitative evidence for disparate combinations of channel and synaptic localization profiles to concomitantly yield similar tuning and similar intrinsic properties.
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spatially dispersed synapses yield sharply tuned place cell responses through Dendritic Spike initiation
bioRxiv, 2017Co-Authors: Reshma Basak, Rishikesh NarayananAbstract:The literature offers evidence for a critical role of spatially-clustered iso-feature synapses in eliciting Dendritic Spikes essential for sharp feature selectivity, with apparently contradictory evidence demonstrating spatial dispersion of iso-feature synapses. Here, we reconcile this apparent contradiction by demonstrating that the generation of Dendritic Spikes, the emergence of an excitatory ramp in somatic voltage responses and sharp tuning of place-cell responses are all attainable even when iso-feature synapses are randomly dispersed across the Dendritic arbor. We found this tuning sharpness to be critically reliant on Dendritic sodium and transient potassium channels and on N-methyl-D-asparate receptors. Importantly, we demonstrate that synaptic potentiation targeted to afferents from one specific place field is sufficient to effectuate place-field selectivity even when intrinsically disparate neurons received randomly dispersed afferents from multiple place-field locations. These conclusions proffer dispersed localization of iso-feature synapses as a strong candidate for achieving sharp feature selectivity in neurons across sensory-perceptual systems.
Yingxue Wang - One of the best experts on this subject based on the ideXlab platform.
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Mismatch reduction through Dendritic nonlinearities in a 2D silicon Dendritic neuron array
2011 IEEE International Symposium of Circuits and Systems (ISCAS), 2011Co-Authors: Yingxue WangAbstract:This paper describes a novel 2D programmable Dendritic neuron array consisting of a 3×32 Dendritic compartment array and a 1×32 somatic compartment array. Each Dendritic compartment contains two types of regenerative nonlinearities: an NMDA nonlinearity and a Dendritic Spike nonlinearity. The chip supports the programmability of local synaptic weights and the configuration of Dendritic morphology for individual neurons through the address-event representation protocol. With a novel local cable circuit between neighboring compartments, different Dendritic morphologies can be constructed. From results measured on a chip fabricated in a 4-metal, 2-poly, 0.35μm CMOS technology, we show one instance of how Dendritic non- linearities can contribute to neuronal computation: the Dendritic Spike mechanism dynamically reduces the mismatch-induced coefficient of variation of the somatic response amplitude from approximately 40% to 3.5%.
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ISCAS - Mismatch reduction through Dendritic nonlinearities in a 2D silicon Dendritic neuron array
2011 IEEE International Symposium of Circuits and Systems (ISCAS), 2011Co-Authors: Yingxue WangAbstract:This paper describes a novel 2D programmable Dendritic neuron array consisting of a 3×32 Dendritic compartment array and a 1×32 somatic compartment array. Each Dendritic compartment contains two types of regenerative nonlinearities: an NMDA nonlinearity and a Dendritic Spike nonlinearity. The chip supports the programmability of local synaptic weights and the configuration of Dendritic morphology for individual neurons through the address-event representation protocol. With a novel local cable circuit between neighboring compartments, different Dendritic morphologies can be constructed. From results measured on a chip fabricated in a 4-metal, 2-poly, 0.35µm CMOS technology, we show one instance of how Dendritic nonlinearities can contribute to neuronal computation: the Dendritic Spike mechanism dynamically reduces the mismatch-induced coefficient of variation of the somatic response amplitude from approximately 40% to 3.5%.
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A Two-Dimensional Configurable Active Silicon Dendritic Neuron Array
IEEE Transactions on Circuits and Systems I: Regular Papers, 2011Co-Authors: Yingxue WangAbstract:This paper presents a 2-D programmable Dendritic neuron array consisting of a 3× 32 Dendritic compartment array and a 1 × 32 somatic compartment array. Each Dendritic compartment contains two types of regenerative nonlinearities: a NMDA synaptic nonlinearity and a Dendritic Spike nonlinearity. The chip supports the programmability of local synaptic weights and the configuration of Dendritic morphology for individual neurons through the address-event representation protocol. Neurons can be stimulated and recorded using the same protocol. A novel local cable circuit between neighboring compartments allows one to construct different Dendritic morphologies. This chip provides a hardware platform for studying the network behavior of neurons with active dendrites and for investigating the role of different Dendritic morphologies in neuronal computation. Based on experimental results from a chip fabricated in a 4-metal, 2-poly, 0.35 μm CMOS technology, this work shows one instance of how Dendritic nonlinearities can contribute to neuronal computation, that is, the Dendritic Spike mechanism can dynamically reduce the mismatch-induced coefficient of variation of the somatic response amplitude from about 40% to 3.5%, and the response timing jitter by a factor of 2.
Alice C. Parker - One of the best experts on this subject based on the ideXlab platform.
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Border ownership in a nano-neuromorphic circuit using nonlinear Dendritic computations
2014 International Joint Conference on Neural Networks (IJCNN), 2014Co-Authors: Alice C. ParkerAbstract:We present an electronic cortical neuron with nonlinear Dendritic computations that performs border-ownership assignment. The circuit is simulated using a carbon nanotube field-effect transistor SPICE model. We demonstrate that our neuron can distinguish convex and concave contours, selectively respond to a figure based on the contour and/or disparity cues, and transform this neural information into a border-ownership signal. We demonstrate that a Dendritic Spike is key to contour detection and increases the robustness of border-ownership neuron firing. We construct an example hierarchical neural network that includes feedforward excitation and lateral inhibition to enhance border-ownership assignment.
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A biomimetic nanoelectronic neuron with enhanced Spike timing
2014 IEEE International Symposium on Circuits and Systems (ISCAS), 2014Co-Authors: Alice C. ParkerAbstract:We present an electronic cortical neuron incorporating both active and passive Dendritic properties. The circuit is simulated using a carbon nanotube field-effect transistor SPICE model. We demonstrate that our neuron can detect coincident spatiotemporal input, and transform this neural information into a precisely-timed output Spike. We also demonstrate that a Dendritic Spike is key to enhance precisely-timed input-output transformation within an individual neuron; without a Dendritic Spike it would require more neurons to achieve the same level of precision. Our simulation results show reliable firing and improved precision of output Spike when a Dendritic Spike is initiated.
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ISCAS - A biomimetic nanoelectronic neuron with enhanced Spike timing
2014 IEEE International Symposium on Circuits and Systems (ISCAS), 2014Co-Authors: Alice C. ParkerAbstract:We present an electronic cortical neuron incorporating both active and passive Dendritic properties. The circuit is simulated using a carbon nanotube field-effect transistor SPICE model. We demonstrate that our neuron can detect coincident spatiotemporal input, and transform this neural information into a precisely-timed output Spike. We also demonstrate that a Dendritic Spike is key to enhance precisely-timed input-output transformation within an individual neuron; without a Dendritic Spike it would require more neurons to achieve the same level of precision. Our simulation results show reliable firing and improved precision of output Spike when a Dendritic Spike is initiated.
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Dynamic Spike threshold and nonlinear Dendritic computation for coincidence detection in neuromorphic circuits
2014 36th Annual International Conference of the IEEE Engineering in Medicine and Biology Society, 2014Co-Authors: Alice C. ParkerAbstract:We present an electronic cortical neuron incorporating dynamic Spike threshold and active Dendritic properties. The circuit is simulated using a carbon nanotube field-effect transistor SPICE model. We demonstrate that our neuron has lower Spike threshold for coincident synaptic inputs; however when the synaptic inputs are not in synchrony, it requires larger depolarization to evoke the neuron to fire. We also demonstrate that a Dendritic Spike is key to precisely-timed input-output transformation, produces reliable firing and results in more resilience to input jitter within an individual neuron.
Reshma Basak - One of the best experts on this subject based on the ideXlab platform.
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Robust emergence of sharply tuned place cell responses in hippocampal neurons with structural and biophysical heterogeneities
bioRxiv, 2019Co-Authors: Reshma Basak, Rishikesh NarayananAbstract:Hippocampal pyramidal neurons sustain propagation of fast electrical signals and are electrotonically non-compact structures exhibiting cell-to-cell variability in their complex Dendritic arborization. In this study, we demonstrate that sharp place-field tuning and several somato-Dendritic functional maps concomitantly emerge despite the presence of geometrical heterogeneities in these neurons. We establish this employing an unbiased stochastic search strategy involving thousands of models that spanned several morphologies and distinct profiles of dispersed synaptic localization and channel expression. Mechanistically, employing virtual knockout models, we explored the impact of bidirectional modulation in Dendritic Spike prevalence on place-field tuning sharpness. Consistent with prior literature, we found that across all morphologies, virtual knockout of either Dendritic fast sodium channels or N-methyl-D-aspartate receptors led to a reduction in Dendritic Spike prevalence, whereas A-type potassium channel knockouts resulted in a nonspecific increase in Dendritic Spike prevalence. However, place-field tuning sharpness was critically impaired in all three sets of virtual knockout models, demonstrating that sharpness in feature tuning is maintained by an intricate balance between mechanisms that promote and those that prevent Dendritic Spike initiation. From the functional standpoint of the emergence of sharp feature tuning and intrinsic functional maps, within this framework, geometric variability was compensated by a combination of synaptic democracy, the ability of randomly dispersed synapses to yield sharp tuning through Dendritic Spike initiation, and ion-channel degeneracy. Our results suggest electrotonically non-compact neurons to be endowed with several degrees of freedom, encompassing channel expression, synaptic localization and morphological micro-structure, in achieving sharp feature encoding and excitability homeostasis.
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spatially dispersed synapses yield sharply tuned place cell responses through Dendritic Spike initiation
The Journal of Physiology, 2018Co-Authors: Reshma Basak, Rishikesh NarayananAbstract:A prominent hypothesis spanning several sensory-perceptual systems implicates spatially clustered synapses in the generation of Dendritic Spikes that mediate sharply-tuned neuronal responses to input features. In this conductance-based morphologically-precise computational study, we tested this hypothesis by systematically analysing the impact of distinct synaptic and channel localization profiles on sharpness of spatial tuning in hippocampal pyramidal neurons. We found that the generation of Dendritic Spikes, the emergence of an excitatory ramp in somatic voltage responses, the expression of several intrinsic somatoDendritic functional maps and sharp tuning of place-cell responses were all attainable even when iso-feature synapses are randomly dispersed across the Dendritic arbor of models with disparate channel combinations. Strikingly, the generation and propagation of Dendritic Spikes, reliant on Dendritic sodium channels and N-methyl-d-asparate receptors, mediated the sharpness of spatial tuning achieved with dispersed synaptic localization. To ensure that our results were not artefacts of narrow parametric choices, we confirmed these conclusions with independent multiparametric stochastic search algorithms spanning thousands of unique models for each synaptic localization scenario.Next, employing virtual knockout models, we demonstrated a vital role for Dendritically expressed voltage-gated ion channels, especially the transient potassium channels, in maintaining sharpness of place-cell tuning. Importantly, we established that synaptic potentiation targeted to afferents from one specific place field was sufficient to impart place field selectivity even when intrinsically disparate neurons received randomly dispersed afferents from multiple place field locations. Our results provide quantitative evidence for disparate combinations of channel and synaptic localization profiles to concomitantly yield similar tuning and similar intrinsic properties.
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Spatially dispersed synapses yield sharply‐tuned place cell responses through Dendritic Spike initiation
The Journal of Physiology, 2018Co-Authors: Reshma Basak, Rishikesh NarayananAbstract:A prominent hypothesis spanning several sensory-perceptual systems implicates spatially clustered synapses in the generation of Dendritic Spikes that mediate sharply-tuned neuronal responses to input features. In this conductance-based morphologically-precise computational study, we tested this hypothesis by systematically analysing the impact of distinct synaptic and channel localization profiles on sharpness of spatial tuning in hippocampal pyramidal neurons. We found that the generation of Dendritic Spikes, the emergence of an excitatory ramp in somatic voltage responses, the expression of several intrinsic somatoDendritic functional maps and sharp tuning of place-cell responses were all attainable even when iso-feature synapses are randomly dispersed across the Dendritic arbor of models with disparate channel combinations. Strikingly, the generation and propagation of Dendritic Spikes, reliant on Dendritic sodium channels and N-methyl-d-asparate receptors, mediated the sharpness of spatial tuning achieved with dispersed synaptic localization. To ensure that our results were not artefacts of narrow parametric choices, we confirmed these conclusions with independent multiparametric stochastic search algorithms spanning thousands of unique models for each synaptic localization scenario.Next, employing virtual knockout models, we demonstrated a vital role for Dendritically expressed voltage-gated ion channels, especially the transient potassium channels, in maintaining sharpness of place-cell tuning. Importantly, we established that synaptic potentiation targeted to afferents from one specific place field was sufficient to impart place field selectivity even when intrinsically disparate neurons received randomly dispersed afferents from multiple place field locations. Our results provide quantitative evidence for disparate combinations of channel and synaptic localization profiles to concomitantly yield similar tuning and similar intrinsic properties.
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spatially dispersed synapses yield sharply tuned place cell responses through Dendritic Spike initiation
bioRxiv, 2017Co-Authors: Reshma Basak, Rishikesh NarayananAbstract:The literature offers evidence for a critical role of spatially-clustered iso-feature synapses in eliciting Dendritic Spikes essential for sharp feature selectivity, with apparently contradictory evidence demonstrating spatial dispersion of iso-feature synapses. Here, we reconcile this apparent contradiction by demonstrating that the generation of Dendritic Spikes, the emergence of an excitatory ramp in somatic voltage responses and sharp tuning of place-cell responses are all attainable even when iso-feature synapses are randomly dispersed across the Dendritic arbor. We found this tuning sharpness to be critically reliant on Dendritic sodium and transient potassium channels and on N-methyl-D-asparate receptors. Importantly, we demonstrate that synaptic potentiation targeted to afferents from one specific place field is sufficient to effectuate place-field selectivity even when intrinsically disparate neurons received randomly dispersed afferents from multiple place-field locations. These conclusions proffer dispersed localization of iso-feature synapses as a strong candidate for achieving sharp feature selectivity in neurons across sensory-perceptual systems.
Michael Häusser - One of the best experts on this subject based on the ideXlab platform.
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Synaptic input patterns triggering local Dendritic Spikes in vivo
BMC Neuroscience, 2015Co-Authors: Lea Goetz, Martine R. Groen, Arnd Roth, Michael HäusserAbstract:Theoretical modelling and experiments in vitro have shown that the computations performed by single neurons critically depend on the spatiotemporal patterns of synaptic input to the neuron [1,2]. While recording the Spike output of neuronal populations in vivo is now routinely possible, the spatiotemporal pattern of synaptic inputs to an entire neuron is still largely inaccessible to experiment. However, recent experiments in which sensory-evoked local Dendritic Spikes were observed in vivo have provided valuable constraints on possible spatiotemporal patterns of synaptic input [3-5]. For example, the synaptic input to layer 2/3 pyramidal neurons in mouse primary visual cortex evokes Dendritic Spikes at high frequencies during visual stimulation at the preferred orientation, but not at non-preferred orientations [3]. Here, we use a biophysical model to explore which spatiotemporal patterns of synaptic inputs can drive the observed Spikes, and in particular the high frequencies in Dendritic Spike bursts. First, we adapted a detailed active compartmental model of a neocortical layer 2/3 pyramidal neuron [3] to reproduce biophysical properties and firing statistics observed in vivo [6], such as firing threshold, mean membrane potentials for UP and DOWN states, and sparse action potential firing in the presence of Poisson distributed background synaptic input. The model generates fast Dendritic Spikes heterogeneous in amplitude, time course and spatial extent, as observed in in vivo experiments [3]. The Dendritic Spikes, together with somatic action potential firing, are abolished by blocking the NMDA receptor-mediated conductance, and their frequency is reduced by hyperpolarization via the Dendritic recording site, again as observed in experiments [3]. Next we analyzed which spatiotemporal synaptic input patterns precede the generation of local Dendritic events. We find that local Spikes are preferentially triggered by excitatory synapses which are spatially and temporally clustered in the local Dendritic branch and neighbouring branches. While there is great variability in the spatial distribution of synapses triggering local Dendritic Spikes, temporal patterns of excitatory synaptic input are stereotyped and tend to be sparse. High-frequency Dendritic Spikes similar to those observed in vivo occur preferentially when excitatory synaptic inputs are interspersed with inhibitory synaptic inputs. Furthermore, local Spikes preceding backpropagating action potentials lead to the highest instantaneous Dendritic Spike frequencies. The highest sustained frequencies are generated by local Spikes initiated sequentially in several neighbouring Dendritic branches. Notably, only some of the high frequency Dendritic events are effective in evoking action potential output, while others remain local. We use cluster analysis to establish the local and global conditions under which specific spatiotemporal patterns of synaptic input can influence neuronal output. In summary, we have derived spatial and temporal rules for synaptic input and identify input patterns that locally exploit the non-linear integration capacities of dendrites. Which computations can be implemented by spiking dendrites receiving such synaptic input patterns? These constraints on synaptic input patterns, together with the realistic intrinsic properties displayed by the model, put us in a position to investigate the role of Dendritic excitability in shaping the input-output relation of the neuron.
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the selfish Spike local and global resets of Dendritic excitability
Neuron, 2009Co-Authors: Tiago Branco, Michael HäusserAbstract:Dendritic Spikes are local events that occasionally propagate successfully to the soma, triggering axonal action potentials that backpropagate into the dendrites. In this issue of Neuron , Remy et al. show that single Dendritic Spikes in hippocampal pyramidal neurons transiently inhibit further Dendritic Spikes in the same branch, while backpropagating action potentials trigger a widespread reduction of Dendritic excitability. Thus, Dendritic Spikes can cause local and global resets of Dendritic Spike generation, which can be exploited for computation and plasticity.
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The origin of the complex Spike in cerebellar Purkinje cells.
J Neurosci, 2008Co-Authors: Michael HäusserAbstract:Activation of the climbing fiber input powerfully excites cerebellar Purkinje cells via hundreds of widespread Dendritic synapses, triggering Dendritic Spikes as well as a characteristic high-frequency burst of somatic Spikes known as the complex Spike. To investigate the relationship between Dendritic Spikes and the Spikelets within the somatic complex Spike, and to evaluate the importance of the Dendritic distribution of climbing fiber synapses, we made simultaneous somatic and Dendritic patch-clamp recordings from Purkinje cells in cerebellar slices. Injection of large climbing fiber-like synaptic conductances at the soma using dynamic clamp was sufficient to reproduce the complex Spike, independently of Dendritic Spikes, indicating that neither a Dendritic synaptic distribution nor Dendritic Spikes are required. Furthermore, we found that Dendritic Spikes are not directly linked to Spikelets in the complex Spike, and that each Dendritic Spike is associated with only 0.24 +/- 0.09 extra somatic Spikelets. Rather, we demonstrate that Dendritic Spikes regulate the pause in firing that follows the complex Spike. Finally, using dual somatic and axonal recording, we show that all Spikelets in the complex Spike are axonally generated. Thus, complex Spike generation proceeds relatively independently of Dendritic Spikes, reflecting the dual functional role of climbing fiber input: triggering plasticity at Dendritic synapses and generating a distinct output signal in the axon. The encoding of Dendritic spiking by the post-complex Spike pause provides a novel computational function for Dendritic Spikes, which could serve to link these two roles at the level of the target neurons in the deep cerebellar nuclei.