Chemogenetic and Optogenetic Manipulations of Microglia in Chronic Pain / 神经科学通报·英文版

Chronic pain relief remains an unmet medical need. Current research points to a substantial contribution of glia-neuron interaction in its pathogenesis. Particularly, microglia play a crucial role in the development of chronic pain. To better understand the microglial contribution to chronic pain, specific regional and temporal manipulations of microglia are necessary. Recently, two new approaches have emerged that meet these demands. Chemogenetic tools allow the expression of designer receptors exclusively activated by designer drugs (DREADDs) specifically in microglia. Similarly, optogenetic tools allow for microglial manipulation via the activation of artificially expressed, light-sensitive proteins. Chemo- and optogenetic manipulations of microglia in vivo are powerful in interrogating microglial function in chronic pain. This review summarizes these emerging tools in studying the role of microglia in chronic pain and highlights their potential applications in microglia-related neurological disorders.

Implantes cocleares ópticos: una herramienta promisoria de tratamiento para la hipoacusia / Optical cochlear implants: a promising treatment tool for hearing loss

La hipoacusia afecta a más de 1.500 millones de personas mundialmente. Los principales medios de rehabilitación usados son los audífonos e implantes cocleares (IC). El IC eléctrico convierte el sonido en impulsos eléctricos que estimulan, directamente, a las neuronas del ganglio espiral para proveer sensación auditiva. Tiene como desventaja una amplia dispersión espacial de la corriente, limitando la resolución espectral y el rango dinámico de codificación sonoro, lo que conduce a una mala comprensión del habla en entornos ruidosos y mala apreciación de la música. En los últimos años se ha estudiado utilizar estimulación óptica en vez de eléctrica, pues emite estímulos con mayor selectividad espacial. Se han descrito IC ópticos usando luz infrarroja y otros con métodos de optogenética, estos últimos requieren de la expresión de proteínas fotosensibles inducidas por virus adenoasociados. Se ha visto que la selectividad espectral de la estimulación optogenética es indistinguible de la acústica, y permitió tasas de disparo casi fisiológicas con buena precisión temporal hasta 250 Hz de estimulación. Estudios que compararon un sistema de IC óptico con uno eléctrico concluyen que el uso de optogenética permitiría una restauración de la audición con una selectividad espectral mejorada en comparación con un IC eléctrico.

Hearing loss affects more than 1.5 billion people worldwide. The main means of rehabilitation used are hearing aids and cochlear implants (CI). The electrical CI converts sound into electrical impulses that directly stimulate neurons in the spiral ganglion to provide auditory sensation; it has the disadvantage of a wide spatial dispersion of the current, limiting the spectral resolution and the dynamic range of sound coding, which leads to a poor understanding of speech in noisy environments and a poor appreciation of music. In recent years, the use of optical stimulation instead of electrical stimulation have been studied since it emits stimuli with greater spatial selectivity. Optical CIs have been described using infrared light and others using optogenetic methods, the latter requiring the expression of photosensitive proteins induced by adeno-associated viruses. The spectral selectivity of optogenetic stimulation has been found to be indistinguishable from acoustic stimulation and allowed near-physiological firing rates with good temporal accuracy up to 250 Hz stimulation. Studies comparing an optical and an electrical CI system conclude that the use of optogenetics would allow hearing restoration with improved spectral selectivity compared to an electrical CI.

Dissecting the Neural Circuitry for Pain Modulation and Chronic Pain: Insights from Optogenetics / 神经科学通报·英文版

Pain is an unpleasant sensory and emotional experience associated with, or resembling that associated with, actual or potential tissue damage. The processing of pain involves complicated modulation at the levels of the periphery, spinal cord, and brain. The pathogenesis of chronic pain is still not fully understood, which makes the clinical treatment challenging. Optogenetics, which combines optical and genetic technologies, can precisely intervene in the activity of specific groups of neurons and elements of the related circuits. Taking advantage of optogenetics, researchers have achieved a body of new findings that shed light on the cellular and circuit mechanisms of pain transmission, pain modulation, and chronic pain both in the periphery and the central nervous system. In this review, we summarize recent findings in pain research using optogenetic approaches and discuss their significance in understanding the pathogenesis of chronic pain.

Optimization of the Light-On system in a lentiviral platform to a light-controlled expression of genes in neurons

BACKGROUND: Molecular brain therapies require the development of molecular switches to control gene expression in a limited and regulated manner in time and space. Light-switchable gene systems allow precise control of gene expression with an enhanced spatio-temporal resolution compared to chemical inducers. In this work, we adapted the existing light-switchable Light-On system into a lentiviral platform, which consists of two modules: (i) one for the expression of the blue light-switchable transactivator GAVPO and (ii) a second module containing an inducible-UAS promoter (UAS) modulated by a light-activated GAVPO. RESULTS: In the HEK293-T cell line transfected with this lentiviral plasmids system, the expression of the reporter mCherry increased between 4 to 5 fold after light induction. A time expression analysis after light induction during 24 h revealed that mRNA levels continuously increased up to 9 h, while protein levels increased throughout the experiment. Finally, transduction of cultured rat hippocampal neurons with this dual Light-On lentiviral system showed that CDNF, a potential therapeutic trophic factor, was induced only in cells exposed to blue light. CONCLUSIONS: In conclusion, the optimized lentiviral platform of the Light-On system provides an efficient way to control gene expression in neurons, suggesting that this platform could potentially be used in biomedical and neuroscience research, and eventually in brain therapies for neurodegenerative diseases.

The effects of optical genetic techniques on new neurons through the Wnt/β-Catenin pathway / 中国应用生理学杂志

OBJECTIVE@#To investigate the effects of optical genetic techniques on new neurons through the Wnt/β-Catenin pathway.@*METHODS@#Neural stem cells (ESCs)were extracted from the cerebral cortex of fetal rat and transfected by lentivirus carrying DCX-ChR2-EGFP gene and the expression of DCX of newborn neurons differentiated from neural stem cells were observed. All cells were divided into 3 groups(n=9): control group, NSCs+EGFP and NSCs+ChR2 groups. The control group was normal cultured NSCs (NSCs group); the neural stem cells in NSCs+EGFP group were transfected with lentivirus carrying EGFP gene. The neural stem cells in NSCs+ChR2 group were infected with lentivirus carrying DCX-ChR2-EGFP gene. After 48 hours of lentivirus infection, 470 nm blue laser irradiation was performed for 3 consecutive days. NeuN positive cell density(the maturation of neural stem cells)and the ratio of NeuN/Hoechst in each group were observed. Western blot was used to detect the expression levels of MAP2, NeuN, Neurog2, NeuroD1 and GluR2. Western blot was used to detect the expressions of β-catenin and TCF4 associated with Wnt/β-catenin signaling channel. Verapamil (100 μmol/L, L-type calcium channel blockers) and Dkk1 (50 μg/ml, β-catenin inhibitor) were used to treat stem cells of the NSCs+ChR2 group and then the expressions of MAP2, NeuN, Neurog2, NeuroD1 and GluR were detected by Western blot.@*RESULTS@#After 3 days of 470 nm blue laser irradiation, NeuN positive cell density(the maturation of neural stem cells)and the ratio of NeuN/Hoechst, the expression levels of the protein MAP2, NeuN, Neurog2, NeuroD1, GluR and the protein β-catenin and TCF4 associated with Wnt/β-catenin signaling channel detected by Western blot were significantly increased in the group of NSCs+ChR2, compared with NSCs and NSCs+EGFP groups. The expressions of MAP2, NeuN, Neurog2, NeuroD1 and GluR were remarkably decreased after treated by verapamil and Dkk1 in the group of NSCs+ChR2. It was proved that the opening of ChR2 channel producing cationic influx promoted the maturation of neural stem cells and induced by the Wnt/β-catenin signaling pathway.@*CONCLUSION@#Optical genetic promoted the maturation of newborn neurons through the Wnt/β-catenin signaling pathway.

Neuroimmune interactions and kidney disease

The autonomic nervous system plays critical roles in maintaining homeostasis in humans, directly regulating inflammation by altering the activity of the immune system. The cholinergic anti-inflammatory pathway is a well-studied neuroimmune interaction involving the vagus nerve. CD4-positive T cells expressing β2 adrenergic receptors and macrophages expressing the alpha 7 subunit of the nicotinic acetylcholine receptor in the spleen receive neurotransmitters such as norepinephrine and acetylcholine and are key mediators of the cholinergic anti-inflammatory pathway. Recent studies have demonstrated that vagus nerve stimulation, ultrasound, and restraint stress elicit protective effects against renal ischemia-reperfusion injury. These protective effects are induced primarily via activation of the cholinergic anti-inflammatory pathway. In addition to these immunological roles, nervous systems are directly related to homeostasis of renal physiology. Whole-kidney three-dimensional visualization using the tissue clearing technique CUBIC (clear, unobstructed brain/body imaging cocktails and computational analysis) has illustrated that renal sympathetic nerves are primarily distributed around arteries in the kidneys and denervated after ischemia-reperfusion injury. In contrast, artificial renal sympathetic denervation has a protective effect against kidney disease progression in murine models. Further studies are needed to elucidate how neural networks are involved in progression of kidney disease.

Next-Generation Tools to Study Autonomic Regulation In Vivo / 神经科学通报·英文版

The recent development of tools to decipher the intricacies of neural networks has improved our understanding of brain function. Optogenetics allows one to assess the direct outcome of activating a genetically-distinct population of neurons. Neurons are tagged with light-sensitive channels followed by photo-activation with an appropriate wavelength of light to functionally activate or silence them, resulting in quantifiable changes in the periphery. Capturing and manipulating activated neuron ensembles, is a recently-designed technique to permanently label activated neurons responsible for a physiological function and manipulate them. On the other hand, neurons can be transfected with genetically-encoded Ca indicators to capture the interplay between them that modulates autonomic end-points or somatic behavior. These techniques work with millisecond temporal precision. In addition, neurons can be manipulated chronically to simulate physiological aberrations by transfecting designer G-protein-coupled receptors exclusively activated by designer drugs. In this review, we elaborate on the fundamental concepts and applications of these techniques in research.

Advances in the simulation of light–tissue interactions in biomedical engineering

Monte Carlo (MC) simulation for light propagation in scattering and absorbing media is the gold standard for studying the interaction of light with biological tissue and has been used for years in a wide variety of cases. The interaction of photons with the medium is simulated based on its optical properties and the original approximation of the scattering phase function. Over the past decade, with the new measurement geometries and recording techniques invented also the corresponding sophisticated methods for the description of the underlying light–tissue interaction taking into account realistic parameters and settings were developed. Applications, such as multiple scattering, optogenetics, optical coherence tomography, Raman spectroscopy, polarimetry and Mueller matrix measurement have emerged and are still constantly improved. Here, we review the advances and recent applications of MC simulation for the active field of the life sciences and the medicine pointing out the new insights enabled by the theoretical concepts.

Development and application of optogenetic tools / 生物工程学报

Dynamic variations of the cell microenvironment can affect cell differentiation, cell signaling pathways, individual growth, and disease. Optogenetics combines gene-encoded protein expression with optical controlling, and offers a novel, reversible, non-invasive and spatiotemporal-specific research tool to dynamically or reversibly regulate cell signaling pathways, subcellular localization and gene expression. This review summarizes the types of optogenetic components and the involved cellular signaling pathways, and explores the application and future prospects of the light-controlled cell signaling pathways.

A Context-Based Analgesia Model in Rats: Involvement of Prefrontal Cortex / 神经科学通报·英文版

Cognition and pain share common neural substrates and interact reciprocally: chronic pain compromises cognitive performance, whereas cognitive processes modulate pain perception. In the present study, we established a non-drug-dependent rat model of context-based analgesia, where two different contexts (dark and bright) were matched with a high (52°C) or low (48°C) temperature in the hot-plate test during training. Before and after training, we set the temperature to the high level in both contexts. Rats showed longer paw licking latencies in trials with the context originally matched to a low temperature than those to a high temperature, indicating successful establishment of a context-based analgesic effect in rats. This effect was blocked by intraperitoneal injection of naloxone (an opioid receptor antagonist) before the probe. The context-based analgesic effect also disappeared after optogenetic activation or inhibition of the bilateral infralimbic or prelimbic sub-region of the prefrontal cortex. In brief, we established a context-based, non-drug dependent, placebo-like analgesia model in the rat. This model provides a new and useful tool for investigating the cognitive modulation of pain.

Optogenetic activation of dorsal hippocampal astrocytic Rac1 blocks the learning of associative memory / 生理学报

Rac1 belongs to the family of Rho GTPases, and plays important roles in the brain function. It affects the cell migration and axon guidance via regulating the cytoskeleton and cellular morphology. However, the effect of its dynamic activation in regulating physiological function remains unclear. Recently, a photoactivatable analogue of Rac1 (PA-Rac1) has been developed, allowing the activation of Rac1 by the specific wavelength of light in living cells. Thus, we constructed recombinant adeno-associated virus (AAV) of PA-Rac1 and its light-insensitive mutant PA-Rac1-C450A under the control of the mouse glial fibrillary acidic protein (mGFAP) promoter to manipulate Rac1 activity in astrocytes by optical stimulation. Primary culture of hippocampal astrocytes was infected with the recombinant AAV-PA-Rac1 or AAV-PA-Rac1-C450A. Real-time fluorescence imaging showed that the cell membrane of the astrocyte expressing PA-Rac1 protruded near the light spot, while the astrocyte expressing PA-Rac1-C450A did not. We injected AAV-PA-Rac1 and AAV-PA-Rac1-C450A into dorsal hippocampus to investigate the role of the activation of Rac1 in regulating the associative learning. With optical stimulation, the PA-Rac1 group, rather than the PA-Rac1-C450A group, showed slower learning curve during the fear conditioning compared with the control group, indicating that activating astrocytic Rac1 blocks the formation of contextual memory. Our data suggest that the activation of Rac1 in dorsal hippocampal astrocyte plays an important role in the associative learning.

Pulse-train Stimulation of Primary Somatosensory Cortex Blocks Pain Perception in Tail Clip Test

Human studies of brain stimulation have demonstrated modulatory effects on the perception of pain. However, whether the primary somatosensory cortical activity is associated with antinociceptive responses remains unknown. Therefore, we examined the antinociceptive effects of neuronal activity evoked by optogenetic stimulation of primary somatosensory cortex. Optogenetic transgenic mice were subjected to continuous or pulse-train optogenetic stimulation of the primary somatosensory cortex at frequencies of 15, 30, and 40 Hz, during a tail clip test. Reaction time was measured using a digital high-speed video camera. Pulse-train optogenetic stimulation of primary somatosensory cortex showed a delayed pain response with respect to a tail clip, whereas no significant change in reaction time was observed with continuous stimulation. In response to the pulse-train stimulation, video monitoring and local field potential recording revealed associated paw movement and sensorimotor rhythms, respectively. Our results show that optogenetic stimulation of primary somatosensory cortex at beta and gamma frequencies blocks transmission of pain signals in tail clip test.

Optogenetic Rescue of Locomotor Dysfunction and Dopaminergic Degeneration Caused by Alpha-Synuclein and EKO Genes

α-Synuclein (α-Syn) is a small presynaptic protein and its mutant forms (e.g. A53T) are known to be directly associated with Parkinson's disease (PD). Pathophysiological mechanisms underlying α-Syn-mediated neurodegeneration in PD still remain to be explored. However, several studies strongly support that overexpression of mutant α-Syn causes reduced release of dopamine (DA) in the brain, and contributes to motor deficits in PD. Using a favorable genetic model Drosophila larva, we examined whether reduced DA release is enough to induce key PD symptoms (i.e. locomotion deficiency and DA neurodegeneration), mimicking a PD gene α-Syn. In order to reduce DA release, we expressed electrical knockout (EKO) gene in DA neurons, which is known to make neurons hypo-excitable. EKO led to a decrease in a DA neuronal marker signal (i.e., TH – tyrosine hydroxylase) and locomotion deficits in Drosophila larva. In contrast, acute and prolonged exposure to blue light (BL, 470 nm) was sufficient to activate channelrhodopsin 2 (ChR2) and rescue PD symptoms caused by both α-Syn and EKO. We believe this is for the first time to confirm that locomotion defects by a genetic PD factor such as α-Syn can be rescued by increasing DA neuronal excitability with an optogenetic approach. Our findings strongly support that PD is a failure of DA synaptic transmission, which can be rescued by optogenetic activation of ChR2.

Inhibition of anterior cingulate cortex excitatory neuronal activity induces conditioned place preference in a mouse model of chronic inflammatory pain

The anterior cingulate cortex (ACC) is known for its role in perception of nociceptive signals and the associated emotional responses. Recent optogenetic studies, involving modulation of neuronal activity in the ACC, show that the ACC can modulate mechanical hyperalgesia. In the present study, we used optogenetic techniques to selectively modulate excitatory pyramidal neurons and inhibitory interneurons in the ACC in a model of chronic inflammatory pain to assess their motivational effect in the conditioned place preference (CPP) test. Selective inhibition of pyramidal neurons induced preference during the CPP test, while activation of parvalbumin (PV)-specific neurons did not. Moreover, chemogenetic inhibition of the excitatory pyramidal neurons alleviated mechanical hyperalgesia, consistent with our previous result. Our results provide evidence for the analgesic effect of inhibition of ACC excitatory pyramidal neurons and a prospective treatment for chronic pain.

Application of optogenetic technique in pain research / 生理学报

Chronic pain represents a major clinical issue which so far is still in shortage of selective and effective treatment. Multiple components are involved in the pain processing, including peripheral, spinal and supraspinal levels of the nervous system. The core to fight the pain problem effectively is to have a good understanding of nociceptive mechanism and the neurobiology of pain perception. Optogenetic technique allows selective activation of subpopulation neurons and provides possibility for better understanding of complex pathway and modulation mechanism in nervous system. Here we review the researches to date that used optogenetic tools for studying pain pathway, and we also provide a brief overview of some new development in optogenetic techniques that may have great potentials in pain research.

Optogenetic Glia Manipulation: Possibilities and Future Prospects

Our brains are composed of two distinct cell types: neurons and glia. Emerging data from recent investigations show that glial cells, especially astrocytes and microglia, are able to regulate synaptic transmission and thus brain information processing. This suggests that, not only neuronal activity, but communication between neurons and glia also plays a key role in brain function. Thus, it is currently well known that the physiology and pathophysiology of brain function can only be completely understood by considering the interplay between neurons and glia. However, it has not yet been possible to dissect glial cell type-specific roles in higher brain functions in vivo. Meanwhile, the recent development of optogenetics techniques has allowed investigators to manipulate neural activity with unprecedented temporal and spatial precision. Recently, a series of studies suggested the possibility of applying this cutting-edge technique to manipulate glial cell activity. This review briefly discusses the feasibility of optogenetic glia manipulation, which may provide a technical innovation in elucidating the in vivo role of glial cells in complex higher brain functions.

Optogenetic and Chemogenetic Approaches for Studying Astrocytes and Gliotransmitters

The brain consists of heterogeneous populations of neuronal and non-neuronal cells. The revelation of their connections and interactions is fundamental to understanding normal brain functions as well as abnormal changes in pathological conditions. Optogenetics and chemogenetics have been developed to allow functional manipulations both in vitro and in vivo to examine causal relationships between cellular changes and functional outcomes. These techniques are based on genetically encoded effector molecules that respond exclusively to exogenous stimuli, such as a certain wavelength of light or a synthetic ligand. Activation of effector molecules provokes diverse intracellular changes, such as an influx or efflux of ions, depolarization or hyperpolarization of membranes, and activation of intracellular signaling cascades. Optogenetics and chemogenetics have been applied mainly to the study of neuronal circuits, but their use in studying non-neuronal cells has been gradually increasing. Here we introduce recent studies that have employed optogenetics and chemogenetics to reveal the function of astrocytes and gliotransmitters.

Brain Stimulation and Modulation for Autism Spectrum Disorder / 한양의대학술지

Autism spectrum disorder (ASD) is characterized by a range of conditions including impairments in social interaction, communication, and restricted and repetitive behaviors. Pharmacological treatments can improve some symptoms of ASD, but the effect is limited and there is a huge unmet demand for successful interventions of ASD. Brain stimulation and modulation are emerging treatment options for ASD: electroconvulsive therapy for catatonia in ASD, vagal nerve stimulation for comorbid epilepsy and ASD, and deep brain stimulation for serious self-injurious behavior. Therapeutic tools are evolving to mechanism-driven treatment. Excitation/Inhibition (E/I) imbalance alters the brain mechanism of information processing and behavioral regulation. Repetitive transcranial magnetic stimulation can stabilize aberrant neuroplasticity by improving E/I balance. These brain stimulation and modulation methods are expected to be used for exploration of the pathophysiology and etiology of ASD and might facilitate the development of a mechanism-driven solution of core domains of ASD in the future.

Closed-loop optogenetic strategy in experimental epilepsy: how affordable Is the implementation of this emergent technique? / Estratégia optogenética de alça fechada na epilepsia experimental: quão acessível é a implementação desta técnica emergente? / Estrategia optogenética de bucle cerrado en la epilepsia experimental: ¿cuán asequible es la aplicación de esta técnica emergente?

To explore complex mechanisms in the brain is an expensive task, which requires a combination of technological development and theoretical advances in neurobiology. In fact, it still is extremely challenging to diagnose accurately and treat some neurological diseases like drug-resistant epilepsy. In some cases, pharmacological interventions, electrical stimulation and surgery in epilepsy can be the specific cause of cognitive impairments and/or psychiatric comorbidities. Therefore, developing more selective strategies to control events produced by abnormal brain activity is mandatory. Our objective was to synthesize and organize information from the literature about the fundamental concepts that support the combination of optogenetics and closed-loop strategies in experimental epilepsy. We also sought to discuss how affordable would be the implementation of these emergent techniques. For this purpose, we first reviewed the literature on the closed-loop optogenetics and its applications for experimental epilepsy. Then, in order to evaluate the feasibility of this approach, we organized the information available in the literature on the materials necessary, and their respective costs. The combination of real-time detection and optogenetics has enormous potential to produce breakthroughs in neuroscience and its use for seizure control will certainly open new possibilities for more effective treatments of epilepsy. Overall, the costs of implementing a robust system with a high temporal precision and accuracy for detection and interference in seizures are relatively small. In addition, costs can be even lower if researchers choose open source hardware tools and software. Therefore, implementation of optogenetics with strategies of closed-loop in experimental epilepsy seems to demand more joint interdisciplinary efforts and innovative scientific questions than financial resources.

Investigar mecanismos complexos no cérebro é uma tarefa dispendiosa, que requer a combinação de desenvolvimento tecnológico e avan- ços teóricos em neurobiologia. De fato, realizar diagnósticos e tratar apropriadamente desordens neurológicas, como epilepsia resistente ao tratamento farmacológico, ainda é um grande desafio. Em alguns casos, as intervenções farmacológicas, a estimulação elétrica e a cirúrgica em epilepsia podem ser as próprias causadoras de prejuízos cognitivos e/ou comorbidades psiquiátricas. Portanto, é mandatório o desenvolvi- mento de estratégias mais seletivas para controlar eventos gerados por atividade anormal do encéfalo. Nosso objetivo foi sintetizar e organizar informações da literatura sobre os conceitos fundamentais que dão suporte à combinação de optogenética e estratégias de alça fechada em epilepsia experimental. Além disso, objetivamos discutir o quão financeiramente acessível seria a implementação dessas novas técnicas. Para isso, primeiramente revisamos a literatura sobre optogenética e estratégias de alça fechada e suas aplicações para epilepsia experimental. Em seguida, com o objetivo de avaliar quão acessível seria essa abordagem, organizamos a informação disponível na literatura sobre os materiais necessários e seus respectivos custos. A combinação de detecção em tempo real e optogenética tem um potencial enorme para produzir avanços em neurociências e seu uso para o controle de crises certamente abrirá novas possibilidades para tratamentos mais eficientes da epilepsia. Em geral, os custos para a implementação de um sistema robusto, com alta precisão temporal e acurácia para detecção e interferência em crises são relativamente pequenos. Além disso, eles podem ser ainda menores se os pesquisadores optarem por ferramentas de hardware e software de fonte aberta. Portanto, a implementação da optogenética com estratégia de alça fechada em epilepsia experimental parece demandar mais esforços interdisciplinares conjuntos e perguntas científicas inovadoras do que recursos financeiros.

Investigar los mecanismos complejos en el cerebro es una tarea costosa, que requiere una combinación de desarrollo tecnológico y los avances teóricos en la neurobiología. De hecho, todavía es um gran desafio diagnosticar con precisión y tratar apropriadamente trastornos neurológicos como la epilepsia resistente al tratamiento farmacológico. En algunos casos, las intervenciones farmacológicas, la estimulación eléctrica y la ciru- gía pueden ser por sí mismas la causa de los deterioros cognitivos y/o comorbilidades psiquiátricas. Por esta razon, es obligatorio el desarrollo de estrategias más selectivas para controlar los eventos producidos por la actividad cerebral anormal. Nuestro objetivo fue sintetizar y organizar la información de la literatura acerca de los conceptos fundamentales que soportan la combinación de la optogenética y estrategias de bucle cerrado en la epilepsia experimental. Además, tratamos de discutir cuán asequible sería la implementación de estas nuevas técnicas. Para ello, primero hemos revisado la literatura sobre la optogenética y las estrategias de bucle cerrado y sus aplicaciones en la epilepsia experimental. Luego, con el fin de evaluar cómo sería este enfoque económico, organizamos la información disponible en la literatura sobre los materiales requeridos y sus costos. La combinación de la detección en tiempo real y la optogenética tiene un enorme potencial para producir avances en la neurociencia y su uso para control de las crisis epilépticas sin duda abrirá nuevas posiblidades para tratamientos más eficaces de la epilepsia. Generalmente, los costos de implementación de un sistema robusto con una alta precisión temporal y la exactitud de detección y de interfencia en las convulsiones son relativamente pequeños. Además, los costos pueden ser incluso más bajos si los pesquisadores eligierenherramientas de hardware y software de código abierto y libre acceso. Por lo tanto, la aplicación de la optogenética con la estrategia de bucle cerrado en la epilepsia experimental parece exigir más esfuerzos interdisciplinarios conjuntos y preguntas científicas innovadoras que recursos financieros.

Optical Tools to Investigate Cellular Activity in the Intestinal Wall

Live imaging has become an essential tool to investigate the coordinated activity and output of cellular networks. Within the last decade, 2 Nobel prizes have been awarded to recognize innovations in the field of imaging: one for the discovery, use, and optimization of the green fluorescent protein (2008) and the second for the development of super-resolved fluorescence microscopy (2014). New advances in both optogenetics and microscopy now enable researchers to record and manipulate activity from specific populations of cells with better contrast and resolution, at higher speeds, and deeper into live tissues. In this review, we will discuss some of the recent developments in microscope technology and in the synthesis of fluorescent probes, both synthetic and genetically encoded. We focus on how live imaging of cellular physiology has progressed our understanding of the control of gastrointestinal motility, and we discuss the hurdles to overcome in order to apply the novel tools in the field of neurogastroenterology and motility.