Light-evoked hyperpolarization and silencing of neurons by conjugated polymers

Feyen, Paul; Colombo, Elisabetta; Endeman, Duco; Nova, Mattia; Laudato, Lucia; Martino, Nicola; Antognazza, Maria Rosa; Lanzani, Guglielmo; Benfenati, Fabio; Ghezzi, Diego

doi:10.1038/srep22718

Cited by 92 publications

(112 citation statements)

References 44 publications

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“…When the light was switched off, a rebound of activity to levels above normal activity was often found (Figure B‐D). The rebound spontaneous firing increase is speculated to come from hyperpolarization‐activated currents as noted by Feyen et al For 56 mW pulsing, corresponding to a temperature of 46°C, the rebound activity was decreased (Figure E). However, for this temperature, we sometimes observed damage so the rebound activity decrease may emanate from an unwanted effect that may affect cell health.…”

Section: Discussionmentioning

confidence: 57%

“…We assume that the inhibition is an effect of increased temperature during pulsing . For a neuron, the mechanism of inhibition is a complex function affected by the heat dependence of membrane conductance, membrane potential, and capacitance changes.…”

Section: Discussionmentioning

confidence: 99%

“…For a neuron, the mechanism of inhibition is a complex function affected by the heat dependence of membrane conductance, membrane potential, and capacitance changes. However, hyperpolarization through an increase in the potassium conductance has been pointed out to be of great importance . It is interesting to note that cooling neurons to room temperature makes them hyperexcitable which follows from a strong dependence on the decrease of the potassium conductance when cooling .…”

Section: Discussionmentioning

confidence: 99%

“…Because the TRP channel family is highly expressed in temperature‐sensing neurons such as DRG neurons , we expect these channels to play less effect on our cortex neurons. Feyen et al excluded the influence of TRPV channels by using IR‐light to modulate the firing activity of mouse hippocampal slices. However, we cannot rule out TRPV channels effects since they also exist in the central nervous system and our neurons are from rat cortex.…”

Section: Discussionmentioning

confidence: 99%

“…Among optical modulations developed, the most promising one is the optogenetic method , which has led to the possibility to modulate specific subpopulations of neurons by genetically transfecting cells with light‐sensitive opsins. The combination of light‐absorbing polymers with visible light or infrared (IR) laser and the combination of nanomaterials with near‐IR light have been introduced as means to suppress the neuronal firing with high efficiency. However, all these techniques require the introduction of exogenous additives to the neuronal targets, which hinders their clinical application.…”

Section: Introductionmentioning

confidence: 99%

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Inhibition of cortical neural networks using infrared laser

Xia

Nyberg

2019

Journal of Biophotonics

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The aim of the present study is to optimize parameters for inhibiting neuronal activity safely and investigating thermal inhibition of rat cortex neural networks in vitro by continuous infrared (IR) laser. Rat cortex neurons were cultured on multi‐electrode arrays until neural networks were formed with spontaneous neural activity. Neurons were then irradiated to inhibit the activity of the networks using different powers of 1550 nm IR laser light. A finite element heating model, calibrated by the open glass pipette method, was used to calculate temperature increases at different laser irradiation intensities. A damage signal ratio (DSR) was evaluated to avoid excessive heating that may damage cells. The DSR predicted that cortex neurons should be safe at temperatures up to 49.6°C for 30 seconds, but experiments suggested that cortex neurons should not be exposed to temperatures over 46°C for 30 seconds. Neural response experiments showed that the inhibition of neural activity is temperature dependent. The normal neural activity could be inhibited safely with an inhibition degree up to 80% and induced epileptiform activity could be suppressed. These results show that continuous IR laser radiations provide a possible way to safely inhibit the neural network activity.

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Section: Discussionmentioning

confidence: 57%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Inhibition of cortical neural networks using infrared laser

Xia

Nyberg

2019

Journal of Biophotonics

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Engineering Materials for Neurotechnology

Ghezzi

2023

Adv Eng Mater

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A crucial issue for a neural interface is the chronic foreign body reaction (FBR) upon implantation. [1][2][3] Avoiding the FBR, or at least reducing its severity, is necessary to preserve the long-term functioning of neural interfaces. [4][5][6] Yet, this is still an open research question. The FBR is traditionally described as a passive barrier encapsulating the device, altering the neural interface, and impairing implant-to-cell communication. [2,7,8] Besides acting as a passive insulating barrier, soluble factors released during the inflammatory and fibrotic process can accelerate device degradation and electrode corrosion. [9] The FBR is inevitable whenever any material becomes in contact with body fluids. [10] In contrast, materials engineering and advanced fabrication processes can minimize its severity, for example, by improving the mechanical compliance of the implant, decreasing the device size, and reducing implantation and chronic trauma. [3] One of the most common limitations of neural interfaces is the mechanical mismatch between the stiff neural implant and the soft neural tissue. This mismatch intensifies the neural damage and FBR caused by insertion, compression, and motion. [11] The neural tissue is curved, soft, dynamic, and subject to deformations caused, for example, by blood pulsation, respiratory pressure, and natural body movements. [11,12] By contrast, most neural interfaces are static and struggle to conform to neural tissue in static and dynamic conditions. A large body of research in neural interfaces addresses this issue using flexible, conformable, or stretchable neural interfaces (Figure 1).Polyimide (PI), parylene-C, and SU-8 are widely used materials in flexible neural interfaces. [13][14][15][16][17][18][19][20][21][22] The advantages of these materials are their biochemical and thermal stability, and their compatibility with clean-room microfabrication processes. [23][24][25] However, they exhibit high Young's modulus (GPa range) and limited elastic deformation (<3%). [26] Ultra-thin neural interfaces made of these materials still reach low bending stiffness if sufficiently thin (<15 μm) despite the high Young's modulus. [27] They can conform to a cylindrical body such as a nerve or a smooth brain surface (Figure 1a), thus reducing the FBR severity. [23] Moreover, ultra-thin neural interfaces with a small cross-sectional area also can minimize tissue damage during penetration (Figure 1b). [22,24,28] Conformability to cylindrical or smooth surfaces is sufficient in rodents, but more is needed for large and complex surfaces with gyri, like in primates, where spherical conformability is required. Because of the limited elastic deformation, conformability to convoluted surfaces is difficult to achieve with these materials. Compliance with neural macro-and micro-movements is also reduced. [26] Elastomers exhibit a lower Young's modulus of at least three orders of magnitude (MPa range) and a much broader elastic regime under strain (>20%). Bending stiffness is influenced by both thick...

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Neuro‐Nano Interfaces: Utilizing Nano‐Coatings and Nanoparticles to Enable Next‐Generation Electrophysiological Recording, Neural Stimulation, and Biochemical Modulation

Young

Cornwell

Daniele

2017

Adv Funct Materials

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to record or modulate electrical activity of the nervous system. Although these electrode systems are both mechanically and operationally robust, they have limited utility due to the resultant macroscale damage from invasive implantation. For this reason, novel nanomaterials are being investigated to enable new strategies to chronically interact with the nervous system at both the cellular and network level. In this feature article, the use of nanomaterials to improve current electrophysiological interfaces, as well as enable new nano-interfaces to modulate neural activity via alternative mechanisms, such as remote transduction of electromagnetic fields are explored. Specifically, this article will review the current use of nanoparticle coatings to enhance electrode function, then an analysis of the cuttingedge, targeted nanoparticle technologies being utilized to interface with both the electrophysiological and biochemical behavior of the nervous system will be provided. Furthermore, an emerging, specialized-use case for neural interfaces will be presented: the modulation of the blood-brain barrier.

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Light-evoked hyperpolarization and silencing of neurons by conjugated polymers

Cited by 92 publications

References 44 publications

Inhibition of cortical neural networks using infrared laser

Inhibition of cortical neural networks using infrared laser

Engineering Materials for Neurotechnology

Neuro‐Nano Interfaces: Utilizing Nano‐Coatings and Nanoparticles to Enable Next‐Generation Electrophysiological Recording, Neural Stimulation, and Biochemical Modulation

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