Multiphysics Finite-Element Modeling of the Neuron/Electrode Electrodiffusive Interaction

Leva, Federico; Verardo, Claudio; Mele, Leandro Julian; Palestri, Pierpaolo; Selmi, L.

doi:10.1109/sensors52175.2022.9967049

Cited by 6 publications

(19 citation statements)

References 13 publications

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“…We point out that further polarization effects may stem from Stern layers at the neuron membrane, but there is no consensus on the necessity to account for them [32], [35] or not [36] in equivalent circuits. Moreover, there are no available strategies to implement them in FEM models while maintaining the ion concentrations close to the membrane within physiological ranges [23]. Thus, we neglect their effects, in line with the other works [14].…”

Section: B Methodology To Derive a Lumped-elements Equivalent Circuitmentioning

confidence: 96%

“…All the physical variables in Figure 1 are space (r and z in a cylindrical reference system) and time (t) dependent but we do not show this explicitly for the sake of a clear notation. Most features of the simulation framework have been detailed in [23]; nevertheless, here we summarize the main model ingredients and the extensions.…”

Section: A Fem Modeling Frameworkmentioning

confidence: 99%

“…For the sake of computationally efficient calculations and differently from [23], we avoid meshing the bulk of the sensing electrode; instead, we collect the transduced electronic signal at the electrode surface (see (13) in Figure 1). The Stern layer on top of the electrode, included via a thin layer approximation, leads to the formation of a diffuse layer in the electrolyte (11) and to a displacement current entering the electrode (12).…”

Section: A Fem Modeling Frameworkmentioning

confidence: 99%

“…The APs are elicited by a transmembrane current pulse lasting 0.5 ms and with an amplitude of ≈0.22 nA applied to the upper HH compartment (i.e., 0.5 A/m 2 ). This choice avoids any overlap between the stimulus and the recorded extracellular signal [23], [35], [56]. We account for the accumulation/depletion of channels in the junctional area (and the consequent depletion/accumulation of non-junctional channels) acting on the µ X i parameter for the sodium and potassium ions in (7) of Figure 1.…”

Section: Validation Of the Equivalent Circuitmentioning

confidence: 99%

“…First, we present an extended version of the FEM model proposed in [23] to investigate continuous and non-uniform ion channel distributions, neuron membranes with domed and ellipsoidal shapes, and realistic planar and mushroom geometries of the sensing electrode. Secondly, we propose a method to derive accurate multicompartmental equivalent circuits for the geometries analyzed with FEM simulations.…”

Section: Introductionmentioning

confidence: 99%

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From Finite Element Simulations to Equivalent Circuit Models of Extracellular Neuronal Recording Systems based on Planar and Mushroom Electrodes

Leva¹,

Verardo²,

Palestri³

et al. 2023

Preprint

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<p>A methodology to build multi-compartment lumped elements equivalent circuits for the neuron/electrode systems is proposed. The equivalent circuit topology is derived by careful scrutiny of accurate multiphysics finite-elements method (FEM) simulations that couple ion transport in the intra- and extracellular fluids, activation of ion channels in the cellular membrane, and signal collection by the electronic readout, thus improving upon most common area contact models.</p> <p>We show that the equivalent circuits derived with our method match with good accuracy the reference FEM simulations over a wide range of geometrical/physical parameters such as the neuron and electrode size, the thickness of the electrolytic cleft, the input impedance of the readout amplifier, even in presence of nonuniform ion channel distributions. The impact of the number of compartments on the model accuracy is also analyzed in detail. We finally illustrate by FEM simulations the effect of extracellular ion transport on the reversal potentials of the Hodgkin-Huxley neuron model and how it can affect the recorded signal for very thin electrolyte clefts between the neuron and the electrode, in a way not yet captured by equivalent circuits of the neuron/electrode system.</p>

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Section: B Methodology To Derive a Lumped-elements Equivalent Circuitmentioning

confidence: 96%

Section: A Fem Modeling Frameworkmentioning

confidence: 99%

Section: A Fem Modeling Frameworkmentioning

confidence: 99%

Section: Validation Of the Equivalent Circuitmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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From Finite Element Simulations to Equivalent Circuit Models of Extracellular Neuronal Recording Systems based on Planar and Mushroom Electrodes

Leva¹,

Verardo²,

Palestri³

et al. 2023

Preprint

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Finite-element modeling of neuromodulation via controlled delivery of potassium ions using conductive polymer-coated microelectrodes

Verardo,

Mele,

Selmi

et al. 2024

J. Neural Eng.

Self Cite

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Objective. The controlled delivery of potassium is an interesting neuromodulation modality, being potassium ions involved in shaping neuron excitability, synaptic transmission, network synchronization, and playing a key role in pathological conditions like epilepsy and spreading depression. Despite many successful examples of pre-clinical devices able to influence the extracellular potassium concentration, computational frameworks capturing the corresponding impact on neuronal activity are still missing. Approach. We present a finite-element model describing a PEDOT:PSS-coated microelectrode (herein, simply ionic actuator) able to release potassium and thus modulate the activity of a cortical neuron in an in-vitro-like setting. The dynamics of ions in the ionic actuator, the neural membrane, and the cellular fluids are solved self-consistently. Main results. We showcase the capability of the model to describe on a physical basis the modulation of the intrinsic excitability of the cell and the synaptic transmission following the electro-ionic stimulation produced by the actuator. We consider three case studies for the ionic actuator with different levels of selectivity to potassium: ideal selectivity, no selectivity, and selectivity achieved by embedding ionophores in the polymer backbone. Significance. This work is the first step toward a comprehensive computational framework aimed to investigate novel neuromodulation devices targeting specific ionic species, as well as to optimize their design and performance, in terms of the induced modulation of neural activity.

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Code Multiplexed Nanocapacitor Arrays for Scalable Neural Recordings

Weaver,

Chen,

Renz

et al. 2024

Preprint

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Large scale neural recordings are redefining our understanding of the brain. However, simultaneously recording potentials from thousands of microelectrodes remains challenging. We overcome this limitation by measuring activity-induced changes in mutual capacitance. Code division multiplexing enabled simultaneous recordings of neural activity from 1,024 nanocapacitor electrodes at a density of 10k electrodes/mm.2Features of neural activityi.e., action potentials, bursts, and local field potentials were measured in recordings, benchmarking our device against the state-of-the-art.SummaryCapacitive sensing of neural activity improves the scalability, fabrication, and miniaturization of microelectrode arrays.

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Multiphysics Finite-Element Modeling of the Neuron/Electrode Electrodiffusive Interaction

Cited by 6 publications

References 13 publications

From Finite Element Simulations to Equivalent Circuit Models of Extracellular Neuronal Recording Systems based on Planar and Mushroom Electrodes

From Finite Element Simulations to Equivalent Circuit Models of Extracellular Neuronal Recording Systems based on Planar and Mushroom Electrodes

Finite-element modeling of neuromodulation via controlled delivery of potassium ions using conductive polymer-coated microelectrodes

Code Multiplexed Nanocapacitor Arrays for Scalable Neural Recordings

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