bioRxiv Science⌕ Search

Biology subjects

Zeldenrust, F.

Publications and source records attributed to Zeldenrust, F..

16 recordsLinked to original sources

Neuromodulatory Control of Cortical Function: Cell-Type Specific Regulation of Neuronal Information Transfer

Neuromodulatory systems such as dopamine and acetylcholine enable cortical circuits to rapidly shift between behavioral states, yet it remains unclear how receptor-specific signaling reshapes what single neurons compute. Here we combined whole-cell recordings from excitatory and inhibitory neurons in layer 2/3 of mouse somatosensory cortex with information-theoretic analyses under frozen-noise stimulation. We quantified stimulus-to-spike information transfer and profiled each neuron across four functional domains: passive membrane biophysics, action potential dynamics, intrinsic adaptation currents, and input feature selectivity captured by spike-triggered averages. Activation of D1, D2, or M1 receptors produced cell-type and receptor-specific changes in fractional information and firing output, demonstrating that neuromodulators regulate encoding beyond simple gain control. Unsupervised clustering revealed that receptor activation reshapes neuronal functional identities, consistent with a dynamic computational phenotype. To identify the organizing principle underlying these transitions, we applied multi-set correlation and factor analysis and found that neuromodulation systematically reorganizes covariance among functional domains. In excitatory neurons, dopaminergic activation led to a decreased coordination between input feature selectivity and other functional properties while strengthening coordination among response based features such as spike dynamics and adaptation. Inhibitory neurons, by contrast, generally exhibited increased coordination across domains. These findings identify neuromodulation as a reconfiguration signal that reshapes not only individual cellular properties but also the architecture linking them, thereby dynamically expanding the computational repertoire of cortical circuits.

neuroscience↗

Neuronal degeneracy reflects context-specific trade-offs between energy and information

Among neurons of the same type, the different electrophysiological parameters vary drastically. It is presently unclear if there is any hidden structure in this diversity and how it relates to neuronal function. One potential source of structure is the evolutionary pressure that has sculpted brains to work in an energy-efficient manner. Here we show that neurons parameters do not vary randomly, but that neurons populate a manifold within their parameter space permitting energy-efficient signaling. This manifold represents a Pareto front of degenerate solutions to the problem of energy-efficiency and explains the prevalence of low to intermediate firing rates (2 - 5 Hz) in neocortex. Furthermore, we show that neurons in different sensory brain areas populate different manifolds and that food restriction induces systematic shifts of neuronal parameters along this manifold. Our results suggest that the large diversity of neuronal properties is actually tightly regulated to ensure energy-efficient signaling in different contexts. In briefWe show that there is hidden structure in the diversity of electrophysiological properties of neurons that is governed by trade-offs between energy consumption and information transmission. HighlightsO_LIWe derive an updated neuronal energy budget for a large class of neuron models. C_LIO_LIComputational modeling predicts a manifold of degenerate solutions to energy-efficient information coding forming a Pareto front in the neuronal parameter space. C_LIO_LINeurons from visual and somatosensory cortex fall on the predicted manifold. C_LIO_LIOptimal energy-efficiency is achieved for intermediate-low firing rates (2 - 5 Hz) as observed in neocortex. C_LIO_LIWe observe an energy-efficient form of non-multiplicative synaptic scaling during food deprivation. C_LI O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=164 SRC="FIGDIR/small/708507v2_ufig1.gif" ALT="Figure 1"> View larger version (36K): org.highwire.dtl.DTLVardef@ca6d36org.highwire.dtl.DTLVardef@1c81ca3org.highwire.dtl.DTLVardef@d03833org.highwire.dtl.DTLVardef@19bc7c_HPS_FORMAT_FIGEXP M_FIG C_FIG

neuroscience↗

From Skin to Cortex: End-to-End Spiking Neural Network Simulation of Tactile Information Flow

Autonomous systems and neuroprosthetic devices demand real-time tactile processing under strict energy and latency constraints. Designing these systems using neuromorphic principles, where communication is event-based and node activity is sparse, could improve their speed and energy efficiency. Here we present an end-to-end spiking neural network model of the ascending tactile pathway, from mechanoreceptors in the skin in humans (or whisker follicles in rodents) to cortical neurons, that operates in an event-driven neuromorphic fashion. The model comprises distinct anatomical stages, (1) three types of mechanoreceptor afferents, (2) trigeminal ganglion, (3) brainstem, (4) thalamic nucleus, and (5) three cortical layers, connected in a feed-forward hierarchy. We demonstrate the models responses to both rodent whisker deflection and human fingertip skin displacement, using information-theoretic analysis, pairwise correlation, and stimulus decoding at each layer. Our results show that tactile information is efficiently encoded and transformed at each stage: stimulus features are represented with high fidelity and reduced redundancy as signals ascend. Notably, simple linear or Bayesian decoders can reliably classify stimulus features from single-neuron activity in the thalamus and cortex for low-noise inputs, highlighting the emergence of robust neural representations. This open-source model is the first to include the mechanosensory periphery in a full tactile pathway simulation, enabling researchers to study how perturbations at any stage affect tactile encoding. Moreover, the network is well-suited for deployment on low-power, real-time neuromorphic hardware, facilitating the development of multi-layer signal processing and tactile navigation algorithms.

neuroscience↗

Stability and Adaptability in Balance: A Dual Mechanism for Metaplasticity in Cortical Networks

1.Circuit dynamics arise from the interaction between the networks connectivity structure and intrinsic neuronal nonlinearities, yet the roles of key structural parameters -- synaptic weight (W) and connection probability (P) -- are usually examined in simplified network models. Using a biologically grounded, multilayer spiking model of thalamocortical microcircuitry, incorporating conductance-based neurons and rodent somatosensory cortex connectivity, we systematically scaled W and P and identified four organising principles of population dynamics. First, stronger synapses monotonically amplified spiking across all populations. Second, increasing connection density produced a weight-dependent bidirectional outcome: adding weak synapses preserved baseline activity, whereas adding strong ones suppressed firing. Third, concurrent increases in W and P yielded sublinear effects, where population activity increased less than expected from the sum of their individual impacts. Fourth, two functional neuronal classes emerged -- scaling-invariant neurons that reliably transmitted thalamic input across connectivity regimes, and variant neurons that spiked selectively under specific connectivity scales. These classes differed in their excitation-inhibition balance, shaped by the strength of recurrent inhibition. Together, our findings show that synaptic weight and connection probability work in concert to define cortical operating regimes and generate the functional diversity in neuronal responses that supports flexible computation.

neuroscience↗

How the layer-dependent ratio of excitatory to inhibitory cells shapes cortical coding in balanced networks

The cerebral cortex exhibits a sophisticated neural architecture across its six layers. Recently, it was found that these layers exhibit different ratios of excitatory to inhibitory (EI) neurons, ranging from 4 to 9. This ratio is a key factor for achieving the often reported balance of excitation and inhibition, a hallmark of cortical computation. Although previous studies have explored various biologically realistic aspects of classical balanced networks, such as the effects of more complex neuronal properties including spike frequency adaptation using adaptive exponential integrate and fire (AdEx) neuron models (1), the temporal evolution of randomly connected balanced networks through second order mean field approximations (2), predictions of nonlinear dynamics across diverse neuron models ranging from integrate and fire to Hodgkin-Huxley formulations, thus bridging population dynamics to neuronal electrophysiology (3), the impact of spatial heterogeneity in balanced networks (4-6), and variations in synaptic timescales (7), the specific effects of differences in excitatory-inhibitory (EI) ratios on layer-specific dynamics and computational properties have, to the best of our knowledge, not yet been addressed. We investigate this question using a sparsely connected network model of excitatory and inhibitory neurons. To keep the network in a physiological range of firing rates, we varied the inhibitory firing threshold or the synaptic strength between excitatory and inhibitory neurons. We find that decreasing the EI ratio allows the network to explore a higher-dimensional space and enhance its capacity to represent complex input. By comparing the empirical EI ratios of layer 2/3 and layer 4 in the rodent barrel cortex, we predict that layer 2/3 has a higher dimensionality and coding capacity than layer 4. Furthermore, our analysis of primary visual cortex data from the Allen Brain Institute corroborates these modeling results, also demonstrating increased dimensionality and coding capabilities of layer 2/3.

neuroscience↗

Understanding Neuronal Diversity: Role of Input Dynamics and Selectivity

Neuronal classification based on morphology, electrophysiology, and molecular markers is often considered static. Here, we challenge this view, showing that functional classification depends on input patterns. Using single-cell recordings from layer 2/3 barrel cortex neurons in mice, we compared responses to step-and-hold versus dynamic frozen noise inputs that mimic presynaptic activity. Action potential and waveform-based classifications varied significantly, highlighting the dynamic nature of neuronal identity. To assess the contribution of input versus neuronal attributes toward classification, we analyzed four attribute sets, namely action potential, passive biophysical, adaptation currents, and linear input filters derived via spike-triggered averages (STA). Our findings revealed that the STA, which captures a neurons selective responsiveness to presynaptic activity, explained the most variance within the population. This highlights input-driven dynamics as key to functional identity, emphasizing the need for physiologically relevant inputs in defining neuronal classes and shifting the focus from static properties to dynamic functional diversity.

neuroscience↗

Electrical diversity of neurons in sensory cortices

The classification of neuronal types is a complex task with numerous molecular, anatomical, and functional (electrical) features have been identified as informative in discriminating neuronal populations. The functional characterization of neurons has traditionally been carried out with predefined sets of parameters such as firing rate and action potential generation threshold. Here we provide an objective method to choose what parameters are most informative about a neurons functional cell type. Using this method we show that despite the significant molecular and anatomical variability across neurons, functional characterization of neuronal activity identifies 9 and 11 distinct neuronal subpopulations in the upper layers of the somatosensory and visual cortices respectively. This novel classification method will help to unravel the functional (electrophysiological) diversity of cellular classes throughout the nervous system. Further, the thorough comparison between the different classes of cells will provide a solid building block for the study of the sensory cortices.

neuroscience↗

Precision not prediction: Body-ownership illusion as a consequence of online precision adaptation under Bayesian inference

Humans can experience body ownership of new (external) body parts, for instance, via visuotactile stimulation. While there are models that capture the influence of such body illusions in body localization and recalibration, the computational mechanism that drives the experience of body ownership of external limbs is still not well understood and under discussion. Here, we describe a mathematical model of the dynamics of this phenomenon via uncertainty minimization. Using the Rubber Hand Illusion (RHI) as a proxy, we show that to properly estimate ones arm position, an agent needs to infer the least uncertain world model that explains the observed reality through online adaptation of the signals relevance, i.e., its precision parameters (the inverse variance of the prediction error signal). Our computational model describes that the illusion is triggered when the sensory precision estimate quickly adapts to account for the increase of sensory noise during the physical stimulation of the rubber hand due to the occlusion of the real hand. This adaptation produces a change in the uncertainty of the body position estimates, yielding a switch of the perceived reality: the "rubber hand is the agents hand" becomes the most plausible model (i.e., it has the least posterior uncertainty). Overall, our theoretical account, along with the numerical simulations provided, suggests that while the perceptual drifts in body localization may be driven by prediction error minimization, body-ownership illusions may be a consequence of estimating the signals precision, i.e., the uncertainty associated with the prediction error.

neuroscience↗

Where top-down meets bottom-up: Cell-type specific connectivity map of the whisker system

Sensorimotor computation integrates bottom-up world state information with top-down knowledge and task goals to form action plans. In the rodent whisker system, a prime model of active sensing, evidence shows neuromodulatory neurotransmitters shape whisker control, affecting whisking frequency and amplitude. Since neuromodulatory neurotransmitters are mostly released from subcortical nuclei and have long-range projections that reach the rest of the central nervous system, mapping the circuits of top-down neuromodulatory control of sensorimotor nuclei will help to systematically address the mechanisms of active sensing. Therefore, we developed a neuroinformatic target discovery pipeline to mine the Allen Institutes Mouse Brain Connectivity Atlas. Using network connectivity analysis, we identified new putative connections along the whisker system and anatomically confirmed the existence of 42 previously unknown monosynaptic connections. Using this data, we updated the sensorimotor connectivity map of the mouse whisker system and developed the first cell-type-specific map of the network. The map includes 157 projections across 18 principal nuclei of the whisker system and neuro-modulatory neurotransmitter-releasing. Performing a graph network analysis of this connectome, we identified cell-type specific hubs, sources, and sinks, provided anatomical evidence for monosynaptic inhibitory projections into all stages of the ascending pathway, and showed that neuromodulatory projections improve network-wide connectivity. These results argue that beyond the modulatory chemical contributions to information processing and transfer in the whisker system, the circuit connectivity features of the neuromodulatory networks position them as nodes of sensory and motor integration.

neuroscience↗

Nonlinear super-resolution signal processing for subcellular analysis of calcium dynamics

Fluorescence imaging of calcium dynamics has revolutionized cellular biology, and especially neuroscience as it allows the study of neural activity across spatially well defined populations. Quantification of fluorescence signals is commonly performed using ratiometric measures. These measures, such as {Delta}F/F, are easy to implement, but they depend on the definition of a baseline, which is often not trivial outside of the measurement of evoked responses, and needs to be defined for every cell (or other cellular compartment) separately. Here, we present a new quantitative measure of fluorescence by taking advantage of the time dimension of the signal. The new method, which we named ARES (Autoregressive RESiduals), is based on the quantification of residuals after linear autoregression and does not require arbitrary baseline assignment. We detail the basic characteristics of the ARES signal, compare it against {Delta}F/F, and quantify the improvement in spatial and temporal resolution of recorded calcium data. We further exemplify its utility in the study of intracellular calcium dynamics by describing the propagation of a calcium wave inside a dendrite. As a robust and accurate method for quantifying fluorescence signals, ARES is particularly well-suited for the study of spontaneous as well as evoked calcium dynamics, subcellular localization of calcium signals, and spatiotemporal tracking of calcium dynamics. HighlightsO_LIA baseline-free quantitative measure of fluorescence is introduced C_LIO_LIThe method, called ARES, is based on autoregression C_LIO_LIARES improves the spatiotemporal resolution of calcium imaging recordings C_LIO_LIIts utility for the localization and spatiotemporal tracking of calcium is shown C_LI

neuroscience↗

A whole-cell recording database of neuromodulatory action in the adult neocortex

BackgroundThe recent release of two large intracellular electrophysiological databases now allows high-dimensional systematic analysis of mechanisms of information processing in the neocortex. Here, to complement these efforts, we introduce a freely and publicly available database that provides a comparative insight into the role of various neuromodulatory transmitters in controlling neural information processing. FindingsA database of in vitro whole-cell patch-clamp recordings from primary somatosensory and motor cortices (layers 2/3) of the adult mice (2-15 months old) from both sexes is introduced. A total of 464 current-clamp experiments from identified excitatory and inhibitory neurons are provided. Experiments include recordings with (i) Step-and-Hold protocol during which the current was transiently held at 10 steps, gradually increasing in amplitude, (ii) "Frozen Noise" injections that model the amplitude and time-varying nature of synaptic inputs to a neuron in biological networks. All experiments follow a within neuron across drug design which includes a vehicle control and a modulation of one of the following targets in the same neuron: dopamine and its receptors D1R, D2R, serotonin 5HT1f receptor, norepinephrine Alpha1, and acetylcholine M1 receptors. ConclusionsThis dataset is the first to provide a systematic and comparative insight into the role of the selected neuromodulators in controlling cellular excitability. The data will help to mechanistically address how bottom-up information processing can be modulated, providing a reference for studying neural coding characteristics and revealing the contribution of neuromodulation to information processing.

neuroscience↗

Information transfer and recovery for the sense of touch

Transformation of postsynaptic potentials (PSPs) into action potentials (APs) is the rate-limiting step of communication in neural networks. The efficiency of this intracellular information transfer also powerfully shapes stimulus representations in sensory cortices. Using whole-cell recordings and information-theoretic measures, we show herein that somatic PSPs accurately represent stimulus location on a trial-by-trial basis in single neurons even 4 synapses away from the sensory periphery in the whisker system. This information is largely lost during AP generation but can be rapidly (<20 ms) recovered using complementary information in local populations in a cell-type-specific manner. These results show that as sensory information is transferred from one neural locus to another, the circuits reconstruct the stimulus with high fidelity so that sensory representations of single neurons faithfully represent the stimulus in the periphery, but only in their PSPs, resulting in lossless information processing for the sense of touch in the primary somatosensory cortex.

neuroscience↗

Cell type specific information transfer for sparse coding

Sensory neurons reconstruct the world from action potentials (spikes) impinging on them. To effectively transfer information about the stimulus to the next processing level, a neuron needs to be able to adapt its working range to the properties of the stimulus. Here, we focus on the intrinsic neural properties that influence information transfer in cortical neurons and how tightly their properties need to be tuned to the stimulus statistics for them to be effective. We start by measuring the intrinsic information encoding properties of putative excitatory and inhibitory neurons in L2/3 of the mouse barrel cortex. Excitatory neurons show high thresholds and strong adaptation, making them fire sparsely and resulting in a strong compression of information, whereas inhibitory neurons that favour fast spiking transfer more information. Next, we turn to computational modelling and ask how two properties influence information transfer: 1) spike-frequency adaptation and 2) the shape of the IV-curve. We find that a subthreshold (but not threshold) adaptation, the h-current, and a properly tuned leak conductance can increase the information transfer of a neuron, whereas threshold adaptation can increase its working range. Finally, we verify the effect of the IV-curve slope in our experimental recordings and show that excitatory neurons form a more heterogeneous population than inhibitory neurons. These relationships between intrinsic neural features and neural coding that had not been quantified before will aid computational, theoretical and systems neuroscientists in understanding how neuronal populations can alter their coding properties, such as through the impact of neuromodulators. Why the variability of intrinsic properties of excitatory neurons is larger than that of inhibitory ones is an exciting question, for which future research is needed. Author summaryIntracellular information transfer from synaptic input to output spike train is necessarily lossy. Here, we explicitly measure the mutual information between a neurons input and spike output and show that information transfer is more lossy and heterogeneous for excitatory than for inhibitory neurons. By using computational modelling we show that the shape of the input-output curve as well as how fast a neuron adapts to its input collectively determine the rate of information loss. These insights will help both experimentalists and modellers in designing and simulating experiments that investigate how network coding properties can adapt to the environment, for instance through the effects of neuromodulators.

neuroscience↗

Cortical representation of touch in silico

With its six layers and ~12000 neurons, a cortical column is a complex network whose function is plausibly greater than the sum of its constituents. Functional characterization of its network components will require going beyond the brute-force modulation of the neural activity of a small group of neurons. Here we introduce an open-source, biologically inspired, computationally efficient network model of the somatosensory cortexs granular and supragranular layers after reconstructing the barrel cortex in soma resolution. Comparisons of the network activity to empirical observations showed that the in silico network replicates the known properties of touch representations and whisker deprivation-induced changes in synaptic strength induced in vivo. Simulations show that the history of the membrane potential acts as a spatial filter that determines the presynaptic population of neurons contributing to a post-synaptic action potential; this spatial filtering might be critical for synaptic integration of top-down and bottom-up information.

neuroscience↗

Efficient and robust coding in heterogeneous recurrent networks

Cortical networks show a large heterogeneity of neuronal properties. However, traditional coding models have focused on homogeneous populations of excitatory and inhibitory neurons. Here, we analytically derive a class of recurrent networks of spiking neurons that close to optimally track a continuously varying input online, based on two assumptions: 1) every spike is decoded linearly and 2) the network aims to reduce the mean-squared error between the input and the estimate. From this we derive a class of predictive coding networks, that unifies encoding and decoding and in which we can investigate the difference between homogeneous networks and heterogeneous networks, in which each neurons represents different features and has different spike-generating properties. We find that in this framework, type 1 and type 2 neurons arise naturally and networks consisting of a heterogeneous population of different neuron types are both more efficient and more robust against correlated noise. We make two experimental predictions: 1) we predict that integrators show strong correlations with other integrators and resonators are correlated with resonators, whereas the correlations are much weaker between neurons with different coding properties and 2) that type 2 neurons are more coherent with the overall network activity than type 1 neurons.

neuroscience↗

A databank for intracellular electrophysiological mapping of the adult somatosensory cortex

BackgroundNeurons in the supragranular layers of the somatosensory cortex integrate sensory (bottom-up) and cognitive/perceptual (top-down) information as they orchestrate communication across cortical columns. It has been inferred, based on intracellular recordings from juvenile animals, that supragranular neurons are electrically mature by the fourth postnatal week. However, the dynamics of the neuronal integration in the adulthood is largely unknown. Electrophysiological characterization of the active properties of these neurons throughout adulthood will help to address the biophysical and computational principles of the neuronal integration.\n\nFindingsHere we provide a database of whole-cell intracellular recordings from 315 neurons located in the supragranular layers (L2/3) of the primary somatosensory cortex in adult mice (9-45 weeks old) from both sexes (females, N=195; males, N=120). Data include 361 somatic current-clamp (CC) and 476 voltage-clamp (VC) experiments, recorded using a step-and-hold protocol (CC, N=257; VC, N=46), frozen noise injections (CC, N=104) and triangular voltage sweeps (VC, 10 (N=132), 50 (N=146) and 100 ms (N=152)), from regular spiking (N=169) and fast-spiking neurons (N=66).\n\nConclusionsThe data can be used to systematically study the properties of somatic integration, and the principles of action potential generation across sexes and across electrically characterized neuronal classes in adulthood. Understanding the principles of the somatic transformation of postsynaptic potentials into action potentials will shed light onto the computational principles of intracellular information transfer in single neurons and information processing in neuronal networks, helping to recreate neuronal functions in artificial systems.

neuroscience↗