China 
Africa 
Explore chapters and articles related to this topic
Optogenetic Modulation of Neural Circuits
Published in Francesco S. Pavone, Shy Shoham, Handbook of Neurophotonics, 2020
Mathias Mahn, Oded Klavir, Ofer Yizhar
Optogenetic technology uses light to control or modulate neuronal function, providing a means of interacting with neurons that is unchallenged in its temporal resolution, spatial resolution, and cell type specificity. First applied in mammalian neurons in 2005 (Boyden et al., 2005; Li et al., 2005), this approach comprises a single-component, genetically encoded system to activate, inhibit, or otherwise modulate the activity of neurons with light. The actuators used in optogenetic technology, essentially converting electromagnetic energy to changes in neuronal excitability, are light-sensitive proteins that serve as ion channels, pumps, or biochemical pathway modulators. These tools, typically proteins of the microbial rhodopsin family (Yizhar et al., 2011a; Zhang et al., 2011), are genetically encoded single-component actuators, which allows for selective targeting to specific cell types and therefore interrogation of individual components of highly complex neural systems. Once the targeted neuronal population expresses the genetically encoded optogenetic tool, its function can be controlled with light. In contrast with pharmacological manipulations, which suffer from diffusion of the active compound and poor temporal control, light is not subject to diffusion and can be delivered with millisecond precision. This provides exquisite experimental control that cannot be matched by other genetically encoded approaches, such as pharmacological manipulation of receptors or another genetically encoded system: designer receptors exclusively activated by designer drugs (DREADDs; Armbruster et al., 2007; Vardy et al., 2015).
Medical device implants for neuromodulation
Published in Ze Zhang, Mahmoud Rouabhia, Simon E. Moulton, Conductive Polymers, 2018
A problem with traditional neuromodulation methods is that stimulation produces undesirable effects at the targeted area and in other brain areas. This lack of precise control can yield side effects from stimulation, such as movement tremors. An optimal neurostimulation technique would produce excitation or inhibition of selected neuronal populations, without producing unwanted effects on other cell populations. Optogenetics is a relatively recent field in biotechnology that integrates genetic engineering, electrophysiology, and optical and electronic engineering (Deisseroth 2015). Optogenetics uses light to control cells, such as neurons, that have been genetically modified to express light-sensitive ion channels. Optogenetics provides millisecond-level control and the ability to selectively activate or inhibit particular genetically defined subpopulations of neurons within a larger neural circuit. At present, optogenetic neuromodulation is at an early stage of development. Technical advances and preclinical animal testing are needed before it can treat human disorders (Williams and Denison 2013).
Bionanotechnological Advances in Neural Recording and Stimulation
Published in Laurent A. Francis, Krzysztof Iniewski, Novel Advances in Microsystems Technologies and Their Applications, 2017
Alper Bozkurt, George C. McConnell
To understand cellular basis of neural computation, neural circuitry needs to be driven with appropriate stimuli. Although arrays of stimulation electrodes have been the most common method to achieve this (Buzsaki 2004), the concerns related to tissue damage caused by electrochemical side reactions have been a limiting factor (Stefan et al. 2001, Merrill et al. 2005). Optical structures of nanoscale biomolecules have been used as a novel way to non-invasively and wirelessly stimulate the neurons with precise temporal and spatial resolution. To replace the traditional current-injection methods and to achieve transduction of optical signal-to-neural response, three nanoscale photostimulation techniques were introduced: activation of a biochemically caged neurotransmitter (glutamate)-containing compound (Callaway and Katz 1993), chemical rendering of ion channels to respond to light (Banghart et al. 2004) and genetic incorporation of light-sensitive proteins into light-insensitive cells (Zhang et al. 2006). Called as ‘optogenetics’, the final method uses specific genetic sequences (opsins) to enable the modulation of ion channels in the presence of light. The convergence of nanotechnology with optogenetics may result in startling and challenging advances over the coming decades (Chamber and Kramer 2008). Optogenetics can be combined with calcium imaging to enable all-optical, high-speed and genetically targeted stimulation and recording of neural activity (Olek et al. 2004). This tool offers promising opportunities to model physiological neural disorders (Gradinaru et al. 2007, Airan et al. 2007a,b).
Deep brain stimulation programming strategies: segmented leads, independent current sources, and future technology
Published in Expert Review of Medical Devices, 2021
Bhavana Patel, Shannon Chiu, Joshua K. Wong, Addie Patterson, Wissam Deeb, Matthew Burns, Pamela Zeilman, Aparna Wagle-Shukla, Leonardo Almeida, Michael S. Okun, Adolfo Ramirez-Zamora
The neuromodulatory effects of DBS are illustrated by computational models that estimate the electric field (EF) and VTA for any given set of programming parameters [147,148]. The EF and VTA generate neuronal activation in a non-selective pattern and can lead to stimulation induced side-effects. One proposal to address the non-selective activation is to incorporate optogenetics into the DBS system. Optogenetic techniques allow specific cells to be selectively activated via a light source [149,150]. In PD rodent models, optogenetics have been shown to be able to selectively inhibit and excite selective local circuitry within the STN [151]. Although the study showed modulation of STN electrophysiology, it did not translate to significant changes in the rodent parkinsonian state. In a similar study, Mastro et al., employed optogenetics in PD mice models to selectively activate various GPe neuronal cell lines [152]. The authors found that global activation of the GPe via optogenetics had no effect on parkinsonian symptoms. However, selective activation of parvalbumin (PV)-expressing GPe neurons provided robust rescue of akinesia and bradykinesia. While these results are encouraging, future studies will be needed to identify the ideal approach or approaches for these types of therapies. Experts have referred to this approach as optogenetically inspired DBS [153].
Mechanism of peripheral nerve modulation and recent applications
Published in International Journal of Optomechatronics, 2021
Heejae Shin, Minseok Kang, Sanghoon Lee
Optogenetics can control ion channels at the cell level, and in the case of LED, on/off can be controlled in microsecond units, so very precise and selective modulation at an accurate time is possible. This has led to the mapping of the brain and peripheral nerves based on function. However, the stability of chronic opsin application has not yet been proven, and the vector targeting human should also be confirmed for stability and efficacy. In addition, in the case of a human with a more bulky and thick tissue, a light transmission technology that can deliver an appropriate intensity of light should be developed.