1
|
El Hajj R, Al Sagheer T, Ballout N. Optogenetics in chronic neurodegenerative diseases, controlling the brain with light: A systematic review. J Neurosci Res 2024; 102:e25321. [PMID: 38588013 DOI: 10.1002/jnr.25321] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2023] [Revised: 02/20/2024] [Accepted: 03/09/2024] [Indexed: 04/10/2024]
Abstract
Neurodegenerative diseases are progressive disorders characterized by synaptic loss and neuronal death. Optogenetics combines optical and genetic methods to control the activity of specific cell types. The efficacy of this approach in neurodegenerative diseases has been investigated in many reviews, however, none of them tackled it systematically. Our study aimed to review systematically the findings of optogenetics and its potential applications in animal models of chronic neurodegenerative diseases and compare it with deep brain stimulation and designer receptors exclusively activated by designer drugs techniques. The search strategy was performed based on the PRISMA guidelines and the risk of bias was assessed following the Systematic Review Centre for Laboratory Animal Experimentation tool. A total of 247 articles were found, of which 53 were suitable for the qualitative analysis. Our data revealed that optogenetic manipulation of distinct neurons in the brain is efficient in rescuing memory impairment, alleviating neuroinflammation, and reducing plaque pathology in Alzheimer's disease. Similarly, this technique shows an advanced understanding of the contribution of various neurons involved in the basal ganglia pathways with Parkinson's disease motor symptoms and pathology. However, the optogenetic application using animal models of Huntington's disease, multiple sclerosis, and amyotrophic lateral sclerosis was limited. Optogenetics is a promising technique that enhanced our knowledge in the research of neurodegenerative diseases and addressed potential therapeutic solutions for managing these diseases' symptoms and delaying their progression. Nevertheless, advanced investigations should be considered to improve optogenetic tools' efficacy and safety to pave the way for their translatability to the clinic.
Collapse
Affiliation(s)
- Rojine El Hajj
- Neuroscience Research Center, Faculty of Medical Sciences, Lebanese University, Beirut, Lebanon
| | - Tareq Al Sagheer
- Neuroscience Research Center, Faculty of Medical Sciences, Lebanese University, Beirut, Lebanon
| | - Nissrine Ballout
- Neuroscience Research Center, Faculty of Medical Sciences, Lebanese University, Beirut, Lebanon
| |
Collapse
|
2
|
Mateus JC, Sousa MM, Burrone J, Aguiar P. Beyond a Transmission Cable-New Technologies to Reveal the Richness in Axonal Electrophysiology. J Neurosci 2024; 44:e1446232023. [PMID: 38479812 PMCID: PMC10941245 DOI: 10.1523/jneurosci.1446-23.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2023] [Revised: 12/13/2023] [Accepted: 12/14/2023] [Indexed: 03/17/2024] Open
Abstract
The axon is a neuronal structure capable of processing, encoding, and transmitting information. This assessment contrasts with a limiting, but deeply rooted, perspective where the axon functions solely as a transmission cable of somatodendritic activity, sending signals in the form of stereotypical action potentials. This perspective arose, at least partially, because of the technical difficulties in probing axons: their extreme length-to-diameter ratio and intricate growth paths preclude the study of their dynamics through traditional techniques. Recent findings are challenging this view and revealing a much larger repertoire of axonal computations. Axons display complex signaling processes and structure-function relationships, which can be modulated via diverse activity-dependent mechanisms. Additionally, axons can exhibit patterns of activity that are dramatically different from those of their corresponding soma. Not surprisingly, many of these recent discoveries have been driven by novel technology developments, which allow for in vitro axon electrophysiology with unprecedented spatiotemporal resolution and signal-to-noise ratio. In this review, we outline the state-of-the-art in vitro toolset for axonal electrophysiology and summarize the recent discoveries in axon function it has enabled. We also review the increasing repertoire of microtechnologies for controlling axon guidance which, in combination with the available cutting-edge electrophysiology and imaging approaches, have the potential for more controlled and high-throughput in vitro studies. We anticipate that a larger adoption of these new technologies by the neuroscience community will drive a new era of experimental opportunities in the study of axon physiology and consequently, neuronal function.
Collapse
Affiliation(s)
- J C Mateus
- i3S- Instituto de Investigação e Inovação em Saúde, Universidade do Porto, 4200-135 Porto, Portugal
| | - M M Sousa
- i3S- Instituto de Investigação e Inovação em Saúde, Universidade do Porto, 4200-135 Porto, Portugal
| | - J Burrone
- MRC Centre for Neurodevelopmental Disorders, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London SE1 1UL, United Kingdom
- Centre for Developmental Neurobiology, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London SE1 1UL, United Kingdom
| | - P Aguiar
- i3S- Instituto de Investigação e Inovação em Saúde, Universidade do Porto, 4200-135 Porto, Portugal
| |
Collapse
|
3
|
Wang J, Platz-Baudin E, Noetzel E, Offenhäusser A, Maybeck V. Expressing Optogenetic Actuators Fused to N-terminal Mucin Motifs Delivers Targets to Specific Subcellular Compartments in Polarized Cells. Adv Biol (Weinh) 2024; 8:e2300428. [PMID: 38015104 DOI: 10.1002/adbi.202300428] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2023] [Revised: 10/31/2023] [Indexed: 11/29/2023]
Abstract
Optogenetics is a powerful approach in neuroscience research. However, other tissues of the body may benefit from controlled ion currents and neuroscience may benefit from more precise optogenetic expression. The present work constructs three subcellularly-targeted optogenetic actuators based on the channelrhodopsin ChR2-XXL, utilizing 5, 10, or 15 tandem repeats (TR) from mucin as N-terminal targeting motifs and evaluates expression in several polarized and non-polarized cell types. The modified channelrhodopsin maintains its electrophysiological properties, which can be used to produce continuous membrane depolarization, despite the expected size of the repeats. This work then shows that these actuators are subcellularly localized in polarized cells. In polarized epithelial cells, all three actuators localize to just the lateral membrane. The TR-tagged constructs also express subcellularly in cortical neurons, where TR5-ChR2XXL and TR10-ChR2XXL mainly target the somatodendrites. Moreover, the transfection efficiencies are shown to be dependent on cell type and tandem repeat length. Overall, this work verifies that the targeting motifs from epithelial cells can be used to localize optogenetic actuators in both epithelia and neurons, opening epithelia processes to optogenetic manipulation and providing new possibilities to target optogenetic tools.
Collapse
Affiliation(s)
- Jiali Wang
- Institute of Biological Information Processing IBI-3, Forschungszentrum Jülich GmbH, 52428, Jülich, Germany
- Faculty of Mathematics, Computer Science and Natural Sciences, RWTH Aachen University, 52062, Aachen, Germany
| | - Eric Platz-Baudin
- Institute of Biological Information Processing IBI-2, Forschungszentrum Jülich GmbH, 52428, Jülich, Germany
| | - Erik Noetzel
- Institute of Biological Information Processing IBI-2, Forschungszentrum Jülich GmbH, 52428, Jülich, Germany
| | - Andreas Offenhäusser
- Institute of Biological Information Processing IBI-3, Forschungszentrum Jülich GmbH, 52428, Jülich, Germany
- Faculty of Mathematics, Computer Science and Natural Sciences, RWTH Aachen University, 52062, Aachen, Germany
| | - Vanessa Maybeck
- Institute of Biological Information Processing IBI-3, Forschungszentrum Jülich GmbH, 52428, Jülich, Germany
| |
Collapse
|
4
|
Singh NK, Ramamourthy B, Hage N, Kappagantu KM. Optogenetics: Illuminating the Future of Hearing Restoration and Understanding Auditory Perception. Curr Gene Ther 2024; 24:208-216. [PMID: 38676313 DOI: 10.2174/0115665232269742231213110937] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2023] [Revised: 10/07/2023] [Accepted: 10/25/2023] [Indexed: 04/28/2024]
Abstract
Hearing loss is a prevalent sensory impairment significantly affecting communication and quality of life. Traditional approaches for hearing restoration, such as cochlear implants, have limitations in frequency resolution and spatial selectivity. Optogenetics, an emerging field utilizing light-sensitive proteins, offers a promising avenue for addressing these limitations and revolutionizing hearing rehabilitation. This review explores the methods of introducing Channelrhodopsin- 2 (ChR2), a key light-sensitive protein, into cochlear cells to enable optogenetic stimulation. Viral- mediated gene delivery is a widely employed technique in optogenetics. Selecting a suitable viral vector, such as adeno-associated viruses (AAV), is crucial in efficient gene delivery to cochlear cells. The ChR2 gene is inserted into the viral vector through molecular cloning techniques, and the resulting viral vector is introduced into cochlear cells via direct injection or round window membrane delivery. This allows for the expression of ChR2 and subsequent light sensitivity in targeted cells. Alternatively, direct cell transfection offers a non-viral approach for ChR2 delivery. The ChR2 gene is cloned into a plasmid vector, which is then combined with transfection agents like liposomes or nanoparticles. This mixture is applied to cochlear cells, facilitating the entry of the plasmid DNA into the target cells and enabling ChR2 expression. Optogenetic stimulation using ChR2 allows for precise and selective activation of specific neurons in response to light, potentially overcoming the limitations of current auditory prostheses. Moreover, optogenetics has broader implications in understanding the neural circuits involved in auditory processing and behavior. The combination of optogenetics and gene delivery techniques provides a promising avenue for improving hearing restoration strategies, offering the potential for enhanced frequency resolution, spatial selectivity, and improved auditory perception.
Collapse
Affiliation(s)
- Namit Kant Singh
- Department of Otorhinolaryngology and Head and Neck Surgery, All India institute of Medical Sciences, Bibinagar, Hyderabad, India
| | - Balaji Ramamourthy
- Department of Otorhinolaryngology and Head and Neck Surgery, All India institute of Medical Sciences, Bibinagar, Hyderabad, India
| | - Neemu Hage
- Department of Otorhinolaryngology and Head and Neck Surgery, All India institute of Medical Sciences, Bibinagar, Hyderabad, India
| | - Krishna Medha Kappagantu
- Department of Otorhinolaryngology and Head and Neck Surgery, All India institute of Medical Sciences, Bibinagar, Hyderabad, India
| |
Collapse
|
5
|
vom Dahl C, Müller CE, Berisha X, Nagel G, Zimmer T. Coupling the Cardiac Voltage-Gated Sodium Channel to Channelrhodopsin-2 Generates Novel Optical Switches for Action Potential Studies. MEMBRANES 2022; 12:907. [PMID: 36295666 PMCID: PMC9607247 DOI: 10.3390/membranes12100907] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/26/2022] [Revised: 09/09/2022] [Accepted: 09/12/2022] [Indexed: 06/16/2023]
Abstract
Voltage-gated sodium (Na+) channels respond to short membrane depolarization with conformational changes leading to pore opening, Na+ influx, and action potential (AP) upstroke. In the present study, we coupled channelrhodopsin-2 (ChR2), the key ion channel in optogenetics, directly to the cardiac voltage-gated Na+ channel (Nav1.5). Fusion constructs were expressed in Xenopus laevis oocytes, and electrophysiological recordings were performed by the two-microelectrode technique. Heteromeric channels retained both typical Nav1.5 kinetics and light-sensitive ChR2 properties. Switching to the current-clamp mode and applying short blue-light pulses resulted either in subthreshold depolarization or in a rapid change of membrane polarity typically seen in APs of excitable cells. To study the effect of individual K+ channels on the AP shape, we co-expressed either Kv1.2 or hERG with one of the Nav1.5-ChR2 fusions. As expected, both delayed rectifier K+ channels shortened AP duration significantly. Kv1.2 currents remarkably accelerated initial repolarization, whereas hERG channel activity efficiently restored the resting membrane potential. Finally, we investigated the effect of the LQT3 deletion mutant ΔKPQ on the AP shape and noticed an extremely prolonged AP duration that was directly correlated to the size of the non-inactivating Na+ current fraction. In conclusion, coupling of ChR2 to a voltage-gated Na+ channel generates optical switches that are useful for studying the effect of individual ion channels on the AP shape. Moreover, our novel optogenetic approach provides the potential for an application in pharmacology and optogenetic tissue-engineering.
Collapse
Affiliation(s)
- Christian vom Dahl
- Institute of Physiology II, University Hospital Jena, Friedrich Schiller University, 07740 Jena, Germany
| | - Christoph Emanuel Müller
- Institute of Physiology II, University Hospital Jena, Friedrich Schiller University, 07740 Jena, Germany
| | - Xhevat Berisha
- Institute of Physiology II, University Hospital Jena, Friedrich Schiller University, 07740 Jena, Germany
| | - Georg Nagel
- Institute of Physiology—Neurophysiology, Julius Maximilians University, 97070 Wuerzburg, Germany
| | - Thomas Zimmer
- Institute of Physiology II, University Hospital Jena, Friedrich Schiller University, 07740 Jena, Germany
| |
Collapse
|
6
|
Papaioannou S, Medini P. Advantages, Pitfalls, and Developments of All Optical Interrogation Strategies of Microcircuits in vivo. Front Neurosci 2022; 16:859803. [PMID: 35837124 PMCID: PMC9274136 DOI: 10.3389/fnins.2022.859803] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2022] [Accepted: 05/30/2022] [Indexed: 12/03/2022] Open
Abstract
The holy grail for every neurophysiologist is to conclude a causal relationship between an elementary behaviour and the function of a specific brain area or circuit. Our effort to map elementary behaviours to specific brain loci and to further manipulate neural activity while observing the alterations in behaviour is in essence the goal for neuroscientists. Recent advancements in the area of experimental brain imaging in the form of longer wavelength near infrared (NIR) pulsed lasers with the development of highly efficient optogenetic actuators and reporters of neural activity, has endowed us with unprecedented resolution in spatiotemporal precision both in imaging neural activity as well as manipulating it with multiphoton microscopy. This readily available toolbox has introduced a so called all-optical physiology and interrogation of circuits and has opened new horizons when it comes to precisely, fast and non-invasively map and manipulate anatomically, molecularly or functionally identified mesoscopic brain circuits. The purpose of this review is to describe the advantages and possible pitfalls of all-optical approaches in system neuroscience, where by all-optical we mean use of multiphoton microscopy to image the functional response of neuron(s) in the network so to attain flexible choice of the cells to be also optogenetically photostimulated by holography, in absence of electrophysiology. Spatio-temporal constraints will be compared toward the classical reference of electrophysiology methods. When appropriate, in relation to current limitations of current optical approaches, we will make reference to latest works aimed to overcome these limitations, in order to highlight the most recent developments. We will also provide examples of types of experiments uniquely approachable all-optically. Finally, although mechanically non-invasive, all-optical electrophysiology exhibits potential off-target effects which can ambiguate and complicate the interpretation of the results. In summary, this review is an effort to exemplify how an all-optical experiment can be designed, conducted and interpreted from the point of view of the integrative neurophysiologist.
Collapse
|
7
|
Kaneko K, Currin CB, Goff KM, Wengert ER, Somarowthu A, Vogels TP, Goldberg EM. Developmentally regulated impairment of parvalbumin interneuron synaptic transmission in an experimental model of Dravet syndrome. Cell Rep 2022; 38:110580. [PMID: 35354025 PMCID: PMC9003081 DOI: 10.1016/j.celrep.2022.110580] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2021] [Revised: 01/09/2022] [Accepted: 03/06/2022] [Indexed: 11/25/2022] Open
Abstract
Dravet syndrome is a neurodevelopmental disorder characterized by epilepsy, intellectual disability, and sudden death due to pathogenic variants in SCN1A with loss of function of the sodium channel subunit Nav1.1. Nav1.1-expressing parvalbumin GABAergic interneurons (PV-INs) from young Scn1a+/− mice show impaired action potential generation. An approach assessing PV-IN function in the same mice at two time points shows impaired spike generation in all Scn1a+/− mice at postnatal days (P) 16–21, whether deceased prior or surviving to P35, with normalization by P35 in surviving mice. However, PV-IN synaptic transmission is dysfunctional in young Scn1a+/− mice that did not survive and in Scn1a+/− mice ≥ P35. Modeling confirms that PV-IN axonal propagation is more sensitive to decreased sodium conductance than spike generation. These results demonstrate dynamic dysfunction in Dravet syndrome: combined abnormalities of PV-IN spike generation and propagation drives early disease severity, while ongoing dysfunction of synaptic transmission contributes to chronic pathology. Dravet syndrome is caused by variants in SCN1A with loss of function of Nav1.1 sodium channels. Kaneko et al. use the “mini-slice” to record at two developmental time points. Impaired spike generation of Nav1.1-expressing PV interneurons in Scn1a+/− mice is transient, while abnormalities of PV interneuron synaptic transmission persist.
Collapse
Affiliation(s)
- Keisuke Kaneko
- Division of Neurology, Department of Pediatrics, The Children's Hospital of Philadelphia, Abramson Research Center, Philadelphia, PA 19104, USA
| | - Christopher B Currin
- The Institute of Science and Technology Austria, Am Campus 1, Klosterneuburg, Austria
| | - Kevin M Goff
- Medical Scientist Training Program (MSTP), The University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA; Neuroscience Graduate Group, The University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA
| | - Eric R Wengert
- Division of Neurology, Department of Pediatrics, The Children's Hospital of Philadelphia, Abramson Research Center, Philadelphia, PA 19104, USA
| | - Ala Somarowthu
- Division of Neurology, Department of Pediatrics, The Children's Hospital of Philadelphia, Abramson Research Center, Philadelphia, PA 19104, USA
| | - Tim P Vogels
- The Institute of Science and Technology Austria, Am Campus 1, Klosterneuburg, Austria
| | - Ethan M Goldberg
- Division of Neurology, Department of Pediatrics, The Children's Hospital of Philadelphia, Abramson Research Center, Philadelphia, PA 19104, USA; Neuroscience Graduate Group, The University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA; Department of Neurology, The University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA; Department of Neuroscience, The University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA.
| |
Collapse
|
8
|
Idzhilova OS, Roshchin MV, Smirnova GR, Malyshev AY. Central Targeting of Channelrhodopsin2 by the Motif of Potassium Channel Kv2.1 Can be Altered Due to Overexpression of the Construct. BIONANOSCIENCE 2021. [DOI: 10.1007/s12668-021-00863-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
|
9
|
An engineered channelrhodopsin optimized for axon terminal activation and circuit mapping. Commun Biol 2021; 4:461. [PMID: 33846537 PMCID: PMC8042110 DOI: 10.1038/s42003-021-01977-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2020] [Accepted: 03/11/2021] [Indexed: 11/09/2022] Open
Abstract
Optogenetic tools such as channelrhodopsin-2 (ChR2) enable the manipulation and mapping of neural circuits. However, ChR2 variants selectively transported down a neuron’s long-range axonal projections for precise presynaptic activation remain lacking. As a result, ChR2 activation is often contaminated by the spurious activation of en passant fibers that compromise the accurate interpretation of functional effects. Here, we explored the engineering of a ChR2 variant specifically localized to presynaptic axon terminals. The metabotropic glutamate receptor 2 (mGluR2) C-terminal domain fused with a proteolytic motif and axon-targeting signal (mGluR2-PA tag) localized ChR2-YFP at axon terminals without disturbing normal transmission. mGluR2-PA-tagged ChR2 evoked transmitter release in distal projection areas enabling lower levels of photostimulation. Circuit connectivity mapping in vivo with the Spike Collision Test revealed that mGluR2-PA-tagged ChR2 is useful for identifying axonal projection with significant reduction in the polysynaptic excess noise. These results suggest that the mGluR2-PA tag helps actuate trafficking to the axon terminal, thereby providing abundant possibilities for optogenetic experiments. Hamada et al. engineer and utilise a channelrhodopsin-2 variant that is localized to presynaptic axon terminals. They demonstrate its use for circuitry mapping in vivo and thus provide a useful tool for future optogenetic experiments
Collapse
|
10
|
Paez Segala MG, Looger LL. Optogenetics. Mol Imaging 2021. [DOI: 10.1016/b978-0-12-816386-3.00092-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
|
11
|
Shemesh OA, Linghu C, Piatkevich KD, Goodwin D, Celiker OT, Gritton HJ, Romano MF, Gao R, Yu CCJ, Tseng HA, Bensussen S, Narayan S, Yang CT, Freifeld L, Siciliano CA, Gupta I, Wang J, Pak N, Yoon YG, Ullmann JFP, Guner-Ataman B, Noamany H, Sheinkopf ZR, Park WM, Asano S, Keating AE, Trimmer JS, Reimer J, Tolias AS, Bear MF, Tye KM, Han X, Ahrens MB, Boyden ES. Precision Calcium Imaging of Dense Neural Populations via a Cell-Body-Targeted Calcium Indicator. Neuron 2020; 107:470-486.e11. [PMID: 32592656 DOI: 10.1016/j.neuron.2020.05.029] [Citation(s) in RCA: 68] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2018] [Revised: 05/09/2019] [Accepted: 05/20/2020] [Indexed: 01/11/2023]
Abstract
Methods for one-photon fluorescent imaging of calcium dynamics can capture the activity of hundreds of neurons across large fields of view at a low equipment complexity and cost. In contrast to two-photon methods, however, one-photon methods suffer from higher levels of crosstalk from neuropil, resulting in a decreased signal-to-noise ratio and artifactual correlations of neural activity. We address this problem by engineering cell-body-targeted variants of the fluorescent calcium indicators GCaMP6f and GCaMP7f. We screened fusions of GCaMP to natural, as well as artificial, peptides and identified fusions that localized GCaMP to within 50 μm of the cell body of neurons in mice and larval zebrafish. One-photon imaging of soma-targeted GCaMP in dense neural circuits reported fewer artifactual spikes from neuropil, an increased signal-to-noise ratio, and decreased artifactual correlation across neurons. Thus, soma-targeting of fluorescent calcium indicators facilitates usage of simple, powerful, one-photon methods for imaging neural calcium dynamics.
Collapse
Affiliation(s)
- Or A Shemesh
- The MIT Media Laboratory, Massachusetts Institute of Technology (MIT), Cambridge, MA, USA; Department of Biological Engineering, MIT, Cambridge, MA, USA; MIT Center for Neurobiological Engineering, MIT, Cambridge, MA, USA; Department of Brain and Cognitive Sciences, MIT, Cambridge, MA, USA; MIT McGovern Institute for Brain Research, MIT, Cambridge, MA, USA; Department of Neurobiology and Pittsburgh Institute for Neurodegenerative Diseases, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Changyang Linghu
- The MIT Media Laboratory, Massachusetts Institute of Technology (MIT), Cambridge, MA, USA; MIT Center for Neurobiological Engineering, MIT, Cambridge, MA, USA; MIT McGovern Institute for Brain Research, MIT, Cambridge, MA, USA; Department of Electrical Engineering and Computer Science, MIT, Cambridge, MA, USA
| | - Kiryl D Piatkevich
- The MIT Media Laboratory, Massachusetts Institute of Technology (MIT), Cambridge, MA, USA; Department of Biological Engineering, MIT, Cambridge, MA, USA; MIT Center for Neurobiological Engineering, MIT, Cambridge, MA, USA; Department of Brain and Cognitive Sciences, MIT, Cambridge, MA, USA; MIT McGovern Institute for Brain Research, MIT, Cambridge, MA, USA; School of Life Sciences, Westlake University, Hangzhou, Zhejiang Province, China
| | - Daniel Goodwin
- The MIT Media Laboratory, Massachusetts Institute of Technology (MIT), Cambridge, MA, USA; MIT Center for Neurobiological Engineering, MIT, Cambridge, MA, USA; MIT McGovern Institute for Brain Research, MIT, Cambridge, MA, USA
| | - Orhan Tunc Celiker
- MIT McGovern Institute for Brain Research, MIT, Cambridge, MA, USA; Department of Electrical Engineering and Computer Science, MIT, Cambridge, MA, USA
| | - Howard J Gritton
- Boston University, Department of Biomedical Engineering, Boston, MA 02215, USA
| | - Michael F Romano
- Boston University, Department of Biomedical Engineering, Boston, MA 02215, USA
| | - Ruixuan Gao
- The MIT Media Laboratory, Massachusetts Institute of Technology (MIT), Cambridge, MA, USA; MIT McGovern Institute for Brain Research, MIT, Cambridge, MA, USA
| | - Chih-Chieh Jay Yu
- The MIT Media Laboratory, Massachusetts Institute of Technology (MIT), Cambridge, MA, USA; Department of Biological Engineering, MIT, Cambridge, MA, USA; MIT McGovern Institute for Brain Research, MIT, Cambridge, MA, USA
| | - Hua-An Tseng
- Boston University, Department of Biomedical Engineering, Boston, MA 02215, USA
| | - Seth Bensussen
- Boston University, Department of Biomedical Engineering, Boston, MA 02215, USA
| | - Sujatha Narayan
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA
| | - Chao-Tsung Yang
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA
| | - Limor Freifeld
- The MIT Media Laboratory, Massachusetts Institute of Technology (MIT), Cambridge, MA, USA; MIT Center for Neurobiological Engineering, MIT, Cambridge, MA, USA; MIT McGovern Institute for Brain Research, MIT, Cambridge, MA, USA; Faculty of Biomedical Engineering, Technion, Haifa, Israel
| | - Cody A Siciliano
- Vanderbilt Center for Addiction Research, Department of Pharmacology, Vanderbilt University, Nashville, TN 37232, USA
| | - Ishan Gupta
- The MIT Media Laboratory, Massachusetts Institute of Technology (MIT), Cambridge, MA, USA; Department of Biological Engineering, MIT, Cambridge, MA, USA; MIT Center for Neurobiological Engineering, MIT, Cambridge, MA, USA; MIT McGovern Institute for Brain Research, MIT, Cambridge, MA, USA
| | - Joyce Wang
- The Picower Institute for Learning and Memory, Department of Brain and Cognitive Sciences, MIT, Cambridge, MA 02139, USA
| | - Nikita Pak
- The MIT Media Laboratory, Massachusetts Institute of Technology (MIT), Cambridge, MA, USA; MIT Center for Neurobiological Engineering, MIT, Cambridge, MA, USA; MIT McGovern Institute for Brain Research, MIT, Cambridge, MA, USA; Department of Mechanical Engineering, MIT, Cambridge, MA, USA
| | - Young-Gyu Yoon
- The MIT Media Laboratory, Massachusetts Institute of Technology (MIT), Cambridge, MA, USA; MIT Center for Neurobiological Engineering, MIT, Cambridge, MA, USA; MIT McGovern Institute for Brain Research, MIT, Cambridge, MA, USA; Department of Electrical Engineering and Computer Science, MIT, Cambridge, MA, USA; School of Electrical Engineering, KAIST Institute for Health Science and Technology, Daejeon, Republic of Korea
| | - Jeremy F P Ullmann
- Epilepsy Genetics Program, Department of Neurology, Boston Children's Hospital & Harvard Medical School, Boston, MA, USA
| | - Burcu Guner-Ataman
- The MIT Media Laboratory, Massachusetts Institute of Technology (MIT), Cambridge, MA, USA
| | - Habiba Noamany
- The Picower Institute for Learning and Memory, Department of Brain and Cognitive Sciences, MIT, Cambridge, MA 02139, USA
| | - Zoe R Sheinkopf
- The MIT Media Laboratory, Massachusetts Institute of Technology (MIT), Cambridge, MA, USA; Department of Neurology, Brigham and Women's Hospital, Boston, MA, USA
| | | | - Shoh Asano
- Internal Medicine Research Unit, Pfizer, Cambridge, MA, USA
| | - Amy E Keating
- Department of Biological Engineering, MIT, Cambridge, MA, USA; Department of Biology, MIT, Cambridge, MA, USA; Koch Institute, MIT, Cambridge, MA 02139, USA
| | - James S Trimmer
- Department of Physiology and Membrane Biology, University of California, Davis School of Medicine, Davis, CA, USA
| | - Jacob Reimer
- Department of Neuroscience, Baylor College of Medicine, Houston, TX, USA; Center for Neuroscience and AI, Baylor College of Medicine, Houston, TX, USA
| | - Andreas S Tolias
- Department of Neuroscience, Baylor College of Medicine, Houston, TX, USA; Center for Neuroscience and AI, Baylor College of Medicine, Houston, TX, USA; Department of Electrical and Computer Engineering, Rice University, Houston, TX, USA
| | - Mark F Bear
- The Picower Institute for Learning and Memory, Department of Brain and Cognitive Sciences, MIT, Cambridge, MA 02139, USA
| | - Kay M Tye
- The Picower Institute for Learning and Memory, Department of Brain and Cognitive Sciences, MIT, Cambridge, MA 02139, USA; Salk Institute for Biological Studies, La Jolla, CA 92037, USA
| | - Xue Han
- Boston University, Department of Biomedical Engineering, Boston, MA 02215, USA
| | - Misha B Ahrens
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA
| | - Edward S Boyden
- The MIT Media Laboratory, Massachusetts Institute of Technology (MIT), Cambridge, MA, USA; Department of Biological Engineering, MIT, Cambridge, MA, USA; MIT Center for Neurobiological Engineering, MIT, Cambridge, MA, USA; Department of Brain and Cognitive Sciences, MIT, Cambridge, MA, USA; MIT McGovern Institute for Brain Research, MIT, Cambridge, MA, USA; Koch Institute, MIT, Cambridge, MA 02139, USA.
| |
Collapse
|
12
|
Chen Y, Jang H, Spratt PWE, Kosar S, Taylor DE, Essner RA, Bai L, Leib DE, Kuo TW, Lin YC, Patel M, Subkhangulova A, Kato S, Feinberg EH, Bender KJ, Knight ZA, Garrison JL. Soma-Targeted Imaging of Neural Circuits by Ribosome Tethering. Neuron 2020; 107:454-469.e6. [PMID: 32574560 DOI: 10.1016/j.neuron.2020.05.005] [Citation(s) in RCA: 47] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2018] [Revised: 03/30/2020] [Accepted: 05/01/2020] [Indexed: 12/18/2022]
Abstract
Neuroscience relies on techniques for imaging the structure and dynamics of neural circuits, but the cell bodies of individual neurons are often obscured by overlapping fluorescence from axons and dendrites in surrounding neuropil. Here, we describe two strategies for using the ribosome to restrict the expression of fluorescent proteins to the neuronal soma. We show first that a ribosome-tethered nanobody can be used to trap GFP in the cell body, thereby enabling direct visualization of previously undetectable GFP fluorescence. We then design a ribosome-tethered GCaMP for imaging calcium dynamics. We show that this reporter faithfully tracks somatic calcium dynamics in the mouse brain while eliminating cross-talk between neurons caused by contaminating neuropil. In worms, this reporter enables whole-brain imaging with faster kinetics and brighter fluorescence than commonly used nuclear GCaMPs. These two approaches provide a general way to enhance the specificity of imaging in neurobiology.
Collapse
Affiliation(s)
- Yiming Chen
- Neuroscience Graduate Program, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Heeun Jang
- Buck Institute for Research on Aging, Novato, CA 94945, USA
| | - Perry W E Spratt
- Neuroscience Graduate Program, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Seher Kosar
- Department of Physiology, University of California, San Francisco, San Francisco, CA 94158, USA
| | - David E Taylor
- Neuroscience Graduate Program, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Rachel A Essner
- Department of Physiology, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Ling Bai
- Department of Physiology, University of California, San Francisco, San Francisco, CA 94158, USA
| | - David E Leib
- Neuroscience Graduate Program, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Tzu-Wei Kuo
- Neuroscience Graduate Program, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Yen-Chu Lin
- Department of Physiology, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Mili Patel
- Neuroscience Graduate Program, University of California, San Francisco, San Francisco, CA 94158, USA
| | | | - Saul Kato
- Neuroscience Graduate Program, University of California, San Francisco, San Francisco, CA 94158, USA; Department of Neurology, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Evan H Feinberg
- Neuroscience Graduate Program, University of California, San Francisco, San Francisco, CA 94158, USA; Department of Anatomy, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Kevin J Bender
- Neuroscience Graduate Program, University of California, San Francisco, San Francisco, CA 94158, USA; Department of Neurology, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Zachary A Knight
- Department of Physiology, University of California, San Francisco, San Francisco, CA 94158, USA; Neuroscience Graduate Program, University of California, San Francisco, San Francisco, CA 94158, USA; Howard Hughes Medical Institute, University of California, San Francisco, San Francisco, CA 94158, USA.
| | - Jennifer L Garrison
- Buck Institute for Research on Aging, Novato, CA 94945, USA; Department of Cellular and Molecular Pharmacology, University of California, San Francisco, San Francisco, CA 94158, USA.
| |
Collapse
|
13
|
Gruver KM, Watt AJ. Optimizing Optogenetic Activation of Purkinje Cell Axons to Investigate the Purkinje Cell - DCN Synapse. Front Synaptic Neurosci 2019; 11:31. [PMID: 31824291 PMCID: PMC6883385 DOI: 10.3389/fnsyn.2019.00031] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2019] [Accepted: 11/04/2019] [Indexed: 11/13/2022] Open
Abstract
Optogenetics is a state-of-the-art tool for interrogating neural circuits. In the cerebellum, Purkinje cells serve as the sole output of the cerebellar cortex where they synapse on neurons in the deep cerebellar nuclei (DCN). To investigate the properties of this synaptic connection, we sought to elicit time-locked single action potentials from Purkinje cell axons. Using optical stimulation of channelrhodopsin-2 (ChR2)-expressing Purkinje cells combined with patch-clamp recordings of Purkinje cells and DCN neurons in acute cerebellar slices, we determine the photostimulation parameters required to elicit single time-locked action potentials from Purkinje cell axons. We show that axons require longer light pulses than somata do to elicit single action potentials and that Purkinje cell axons are also more susceptible to light perturbations. We then demonstrate that these empirically determined photostimulation parameters elicit time-locked synaptic currents from postsynaptic cells in the DCN. Our results highlight the importance of optimizing optogenetic stimulation conditions to interrogate synaptic connections.
Collapse
Affiliation(s)
- Kim M Gruver
- Department of Biology, McGill University, Montreal, QC, Canada.,Integrated Program in Neuroscience, McGill University, Montreal, QC, Canada
| | - Alanna J Watt
- Department of Biology, McGill University, Montreal, QC, Canada
| |
Collapse
|
14
|
Alpizar SA, Baker AL, Gulledge AT, Hoppa MB. Loss of Neurofascin-186 Disrupts Alignment of AnkyrinG Relative to Its Binding Partners in the Axon Initial Segment. Front Cell Neurosci 2019; 13:1. [PMID: 30723396 PMCID: PMC6349729 DOI: 10.3389/fncel.2019.00001] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2018] [Accepted: 01/07/2019] [Indexed: 12/14/2022] Open
Abstract
The axon initial segment (AIS) is a specialized region within the proximal portion of the axon that initiates action potentials thanks in large part to an enrichment of sodium channels. The scaffolding protein ankyrinG (AnkG) is essential for the recruitment of sodium channels as well as several other intracellular and extracellular proteins to the AIS. In the present study, we explore the role of the cell adhesion molecule (CAM) neurofascin-186 (NF-186) in arranging the individual molecular components of the AIS in cultured rat hippocampal neurons. Using a CRISPR depletion strategy to ablate NF expression, we found that the loss of NF selectively perturbed AnkG accumulation and its relative proximal distribution within the AIS. We found that the overexpression of sodium channels could restore AnkG accumulation, but not its altered distribution within the AIS without NF present. We go on to show that although the loss of NF altered AnkG distribution, sodium channel function within the AIS remained normal. Taken together, these results demonstrate that the regulation of AnkG and sodium channel accumulation within the AIS can occur independently of one another, potentially mediated by other binding partners such as NF.
Collapse
Affiliation(s)
- Scott A Alpizar
- Department of Biological Sciences, Dartmouth College, Hanover, NH, United States
| | - Arielle L Baker
- Department of Molecular and Systems Biology, Geisel School of Medicine at Dartmouth College, Hanover, NH, United States
| | - Allan T Gulledge
- Department of Molecular and Systems Biology, Geisel School of Medicine at Dartmouth College, Hanover, NH, United States
| | - Michael B Hoppa
- Department of Biological Sciences, Dartmouth College, Hanover, NH, United States
| |
Collapse
|
15
|
Mossy Cells Control Adult Neural Stem Cell Quiescence and Maintenance through a Dynamic Balance between Direct and Indirect Pathways. Neuron 2018; 99:493-510.e4. [PMID: 30057205 DOI: 10.1016/j.neuron.2018.07.010] [Citation(s) in RCA: 68] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2017] [Revised: 05/16/2018] [Accepted: 07/05/2018] [Indexed: 11/23/2022]
Abstract
Mossy cells (MCs) represent a major population of excitatory neurons in the adult dentate gyrus, a brain region where new neurons are generated from radial neural stem cells (rNSCs) throughout life. Little is known about the role of MCs in regulating rNSCs. Here we demonstrate that MC commissural projections structurally and functionally interact with rNSCs through both the direct glutamatergic MC-rNSC pathway and the indirect GABAergic MC-local interneuron-rNSC pathway. Specifically, moderate MC activation increases rNSC quiescence through the dominant indirect pathway, while high MC activation increases rNSC activation through the dominant direct pathway. In contrast, MC inhibition or ablation leads to a transient increase of rNSC activation, but rNSC depletion only occurs after chronic ablation of MCs. Together, our study identifies MCs as a critical stem cell niche component that dynamically controls adult NSC quiescence and maintenance under various MC activity states through a balance of direct glutamatergic and indirect GABAergic signaling onto rNSCs.
Collapse
|
16
|
Anastasiades PG, Marques‐Smith A, Butt SJB. Studies of cortical connectivity using optical circuit mapping methods. J Physiol 2018; 596:145-162. [PMID: 29110301 PMCID: PMC5767689 DOI: 10.1113/jp273463] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2017] [Accepted: 10/11/2017] [Indexed: 11/08/2022] Open
Abstract
An important consideration when probing the function of any neuron is to uncover the source of synaptic input onto the cell, its intrinsic physiology and efferent targets. Over the years, electrophysiological approaches have generated considerable insight into these properties in a variety of cortical neuronal subtypes and circuits. However, as researchers explore neuronal function in greater detail, they are increasingly turning to optical techniques to bridge the gap between local network interactions and behaviour. The application of optical methods has increased dramatically over the past decade, spurred on by the optogenetic revolution. In this review, we provide an account of recent innovations, providing researchers with a primer detailing circuit mapping strategies in the cerebral cortex. We will focus on technical aspects of performing neurotransmitter uncaging and channelrhodopsin-assisted circuit mapping, with the aim of identifying common pitfalls that can negatively influence the collection of reliable data.
Collapse
|
17
|
Shemesh OA, Tanese D, Zampini V, Linghu C, Piatkevich K, Ronzitti E, Papagiakoumou E, Boyden ES, Emiliani V. Temporally precise single-cell-resolution optogenetics. Nat Neurosci 2017; 20:1796-1806. [PMID: 29184208 PMCID: PMC5726564 DOI: 10.1038/s41593-017-0018-8] [Citation(s) in RCA: 149] [Impact Index Per Article: 21.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2016] [Accepted: 09/26/2017] [Indexed: 02/07/2023]
Abstract
Optogenetic control of individual neurons with high temporal precision within intact mammalian brain circuitry would enable powerful explorations of how neural circuits operate. Two-photon computer-generated holography enables precise sculpting of light and could in principle enable simultaneous illumination of many neurons in a network, with the requisite temporal precision to simulate accurate neural codes. We designed a high-efficacy soma-targeted opsin, finding that fusing the N-terminal 150 residues of kainate receptor subunit 2 (KA2) to the recently discovered high-photocurrent channelrhodopsin CoChR restricted expression of this opsin primarily to the cell body of mammalian cortical neurons. In combination with two-photon holographic stimulation, we found that this somatic CoChR (soCoChR) enabled photostimulation of individual cells in mouse cortical brain slices with single-cell resolution and <1-ms temporal precision. We used soCoChR to perform connectivity mapping on intact cortical circuits.
Collapse
Affiliation(s)
- Or A Shemesh
- Media Laboratory, Massachusetts Institute of Technology (MIT), Cambridge, MA, USA
- Department of Biological Engineering, MIT, Cambridge, MA, USA
- Center for Neurobiological Engineering, MIT, Cambridge, MA, USA
- Department of Brain and Cognitive Sciences, MIT, Cambridge, MA, USA
- McGovern Institute for Brain Research, MIT, Cambridge, MA, USA
| | - Dimitrii Tanese
- Neurophotonics Laboratory, Wave Front Engineering Microscopy Group, CNRS UMR8250, Université Paris Descartes, Paris, France
| | - Valeria Zampini
- Neurophotonics Laboratory, Wave Front Engineering Microscopy Group, CNRS UMR8250, Université Paris Descartes, Paris, France
- Institut de la Vision, UM 80, UPMC, Paris, France
| | - Changyang Linghu
- Media Laboratory, Massachusetts Institute of Technology (MIT), Cambridge, MA, USA
- Department of Biological Engineering, MIT, Cambridge, MA, USA
- Center for Neurobiological Engineering, MIT, Cambridge, MA, USA
- Department of Brain and Cognitive Sciences, MIT, Cambridge, MA, USA
- McGovern Institute for Brain Research, MIT, Cambridge, MA, USA
| | - Kiryl Piatkevich
- Media Laboratory, Massachusetts Institute of Technology (MIT), Cambridge, MA, USA
- Department of Biological Engineering, MIT, Cambridge, MA, USA
- Center for Neurobiological Engineering, MIT, Cambridge, MA, USA
- Department of Brain and Cognitive Sciences, MIT, Cambridge, MA, USA
- McGovern Institute for Brain Research, MIT, Cambridge, MA, USA
| | - Emiliano Ronzitti
- Neurophotonics Laboratory, Wave Front Engineering Microscopy Group, CNRS UMR8250, Université Paris Descartes, Paris, France
- Institut de la Vision, UM 80, UPMC, Paris, France
| | - Eirini Papagiakoumou
- Neurophotonics Laboratory, Wave Front Engineering Microscopy Group, CNRS UMR8250, Université Paris Descartes, Paris, France
- Institut national de la santé et de la recherche médicale (Inserm), Paris, France
| | - Edward S Boyden
- Media Laboratory, Massachusetts Institute of Technology (MIT), Cambridge, MA, USA.
- Department of Biological Engineering, MIT, Cambridge, MA, USA.
- Center for Neurobiological Engineering, MIT, Cambridge, MA, USA.
- Department of Brain and Cognitive Sciences, MIT, Cambridge, MA, USA.
- McGovern Institute for Brain Research, MIT, Cambridge, MA, USA.
| | - Valentina Emiliani
- Neurophotonics Laboratory, Wave Front Engineering Microscopy Group, CNRS UMR8250, Université Paris Descartes, Paris, France.
| |
Collapse
|
18
|
Temporally precise single-cell-resolution optogenetics. Nat Neurosci 2017; 20. [PMID: 29184208 PMCID: PMC5726564 DOI: 10.1038/s41593-017-0018-8+10.1038/s41593-018-0097-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Optogenetic control of individual neurons with high temporal precision within intact mammalian brain circuitry would enable powerful explorations of how neural circuits operate. Two-photon computer-generated holography enables precise sculpting of light and could in principle enable simultaneous illumination of many neurons in a network, with the requisite temporal precision to simulate accurate neural codes. We designed a high-efficacy soma-targeted opsin, finding that fusing the N-terminal 150 residues of kainate receptor subunit 2 (KA2) to the recently discovered high-photocurrent channelrhodopsin CoChR restricted expression of this opsin primarily to the cell body of mammalian cortical neurons. In combination with two-photon holographic stimulation, we found that this somatic CoChR (soCoChR) enabled photostimulation of individual cells in mouse cortical brain slices with single-cell resolution and <1-ms temporal precision. We used soCoChR to perform connectivity mapping on intact cortical circuits.
Collapse
|
19
|
Optogenetic Tools for Subcellular Applications in Neuroscience. Neuron 2017; 96:572-603. [PMID: 29096074 DOI: 10.1016/j.neuron.2017.09.047] [Citation(s) in RCA: 217] [Impact Index Per Article: 31.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2016] [Revised: 03/30/2017] [Accepted: 09/26/2017] [Indexed: 12/21/2022]
Abstract
The ability to study cellular physiology using photosensitive, genetically encoded molecules has profoundly transformed neuroscience. The modern optogenetic toolbox includes fluorescent sensors to visualize signaling events in living cells and optogenetic actuators enabling manipulation of numerous cellular activities. Most optogenetic tools are not targeted to specific subcellular compartments but are localized with limited discrimination throughout the cell. Therefore, optogenetic activation often does not reflect context-dependent effects of highly localized intracellular signaling events. Subcellular targeting is required to achieve more specific optogenetic readouts and photomanipulation. Here we first provide a detailed overview of the available optogenetic tools with a focus on optogenetic actuators. Second, we review established strategies for targeting these tools to specific subcellular compartments. Finally, we discuss useful tools and targeting strategies that are currently missing from the optogenetics repertoire and provide suggestions for novel subcellular optogenetic applications.
Collapse
|
20
|
|
21
|
Govorunova EG, Sineshchekov OA, Li H, Spudich JL. Microbial Rhodopsins: Diversity, Mechanisms, and Optogenetic Applications. Annu Rev Biochem 2017; 86:845-872. [PMID: 28301742 PMCID: PMC5747503 DOI: 10.1146/annurev-biochem-101910-144233] [Citation(s) in RCA: 242] [Impact Index Per Article: 34.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Microbial rhodopsins are a family of photoactive retinylidene proteins widespread throughout the microbial world. They are notable for their diversity of function, using variations of a shared seven-transmembrane helix design and similar photochemical reactions to carry out distinctly different light-driven energy and sensory transduction processes. Their study has contributed to our understanding of how evolution modifies protein scaffolds to create new protein chemistry, and their use as tools to control membrane potential with light is fundamental to optogenetics for research and clinical applications. We review the currently known functions and present more in-depth assessment of three functionally and structurally distinct types discovered over the past two years: (a) anion channelrhodopsins (ACRs) from cryptophyte algae, which enable efficient optogenetic neural suppression; (b) cryptophyte cation channelrhodopsins (CCRs), structurally distinct from the green algae CCRs used extensively for neural activation and from cryptophyte ACRs; and
Collapse
Affiliation(s)
- Elena G Govorunova
- Center for Membrane Biology, Department of Biochemistry and Molecular Biology, McGovern Medical School, University of Texas Health Science Center at Houston, Houston, Texas 77030; , , ,
| | - Oleg A Sineshchekov
- Center for Membrane Biology, Department of Biochemistry and Molecular Biology, McGovern Medical School, University of Texas Health Science Center at Houston, Houston, Texas 77030; , , ,
| | - Hai Li
- Center for Membrane Biology, Department of Biochemistry and Molecular Biology, McGovern Medical School, University of Texas Health Science Center at Houston, Houston, Texas 77030; , , ,
| | - John L Spudich
- Center for Membrane Biology, Department of Biochemistry and Molecular Biology, McGovern Medical School, University of Texas Health Science Center at Houston, Houston, Texas 77030; , , ,
| |
Collapse
|
22
|
Wu W, Xiong W, Zhang P, Chen L, Fang J, Shields C, Xu XM, Jin X. Increased threshold of short-latency motor evoked potentials in transgenic mice expressing Channelrhodopsin-2. PLoS One 2017; 12:e0178803. [PMID: 28562670 PMCID: PMC5451077 DOI: 10.1371/journal.pone.0178803] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2017] [Accepted: 05/18/2017] [Indexed: 01/28/2023] Open
Abstract
Transgenic mice that express channelrhodopsin-2 or its variants provide a powerful tool for optogenetic study of the nervous system. Previous studies have established that introducing such exogenous genes usually does not alter anatomical, electrophysiological, and behavioral properties of neurons in these mice. However, in a line of Thy1-ChR2-YFP transgenic mice (line 9, Jackson lab), we found that short-latency motor evoked potentials (MEPs) induced by transcranial magnetic stimulation had a longer latency and much lower amplitude than that of wild type mice. MEPs evoked by transcranial electrical stimulation also had a much higher threshold in ChR2 mice, although similar amplitudes could be evoked in both wild and ChR2 mice at maximal stimulation. In contrast, long-latency MEPs evoked by electrically stimulating the motor cortex were similar in amplitude and latency between wild type and ChR2 mice. Whole-cell patch clamp recordings from layer V pyramidal neurons of the motor cortex in ChR2 mice revealed no significant differences in intrinsic membrane properties and action potential firing in response to current injection. These data suggest that corticospinal tract is not accountable for the observed abnormality. Motor behavioral assessments including BMS score, rotarod, and grid-walking test showed no significant differences between the two groups. Because short-latency MEPs are known to involve brainstem reticulospinal tract, while long-latency MEPs mainly involve primary motor cortex and dorsal corticospinal tract, we conclude that this line of ChR2 transgenic mice has normal function of motor cortex and dorsal corticospinal tract, but reduced excitability and responsiveness of reticulospinal tracts. This abnormality needs to be taken into account when using these mice for related optogenetic study.
Collapse
Affiliation(s)
- Wei Wu
- Department of Neurological Surgery, Stark Neuroscience Research Institute, Indiana University School of Medicine, Indianapolis, Indiana, United States of America.,Spinal Cord and Brain Injury Research Group, Stark Neuroscience Research Institute, Indiana University School of Medicine, Indianapolis, Indiana, United States of America
| | - Wenhui Xiong
- Spinal Cord and Brain Injury Research Group, Stark Neuroscience Research Institute, Indiana University School of Medicine, Indianapolis, Indiana, United States of America.,Department of Anatomy and Cell Biology, Stark Neuroscience Research Institute, Indiana University School of Medicine, Indianapolis, Indiana, United States of America
| | - Ping Zhang
- Norton Neuroscience Institute, Norton Healthcare, Louisville, Kentucky, United States of America
| | - Lifang Chen
- Department of Anatomy and Cell Biology, Stark Neuroscience Research Institute, Indiana University School of Medicine, Indianapolis, Indiana, United States of America.,Department of Acupuncture, Third Affiliated Hospital of Zhejiang Chinese Medical University, Hangzhou, Zhejiang Province, China
| | - Jianqiao Fang
- Department of Acupuncture, Third Affiliated Hospital of Zhejiang Chinese Medical University, Hangzhou, Zhejiang Province, China.,Zhejiang Chinese Medical University, Hangzhou, China
| | - Christopher Shields
- Norton Neuroscience Institute, Norton Healthcare, Louisville, Kentucky, United States of America
| | - Xiao-Ming Xu
- Department of Neurological Surgery, Stark Neuroscience Research Institute, Indiana University School of Medicine, Indianapolis, Indiana, United States of America.,Spinal Cord and Brain Injury Research Group, Stark Neuroscience Research Institute, Indiana University School of Medicine, Indianapolis, Indiana, United States of America.,Department of Anatomy and Cell Biology, Stark Neuroscience Research Institute, Indiana University School of Medicine, Indianapolis, Indiana, United States of America
| | - Xiaoming Jin
- Department of Neurological Surgery, Stark Neuroscience Research Institute, Indiana University School of Medicine, Indianapolis, Indiana, United States of America.,Spinal Cord and Brain Injury Research Group, Stark Neuroscience Research Institute, Indiana University School of Medicine, Indianapolis, Indiana, United States of America.,Department of Anatomy and Cell Biology, Stark Neuroscience Research Institute, Indiana University School of Medicine, Indianapolis, Indiana, United States of America
| |
Collapse
|
23
|
Christie IK, Miller P, Van Hooser SD. Cortical amplification models of experience-dependent development of selective columns and response sparsification. J Neurophysiol 2017; 118:874-893. [PMID: 28515285 DOI: 10.1152/jn.00177.2017] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2017] [Revised: 04/28/2017] [Accepted: 05/11/2017] [Indexed: 02/05/2023] Open
Abstract
The development of direction-selective cortical columns requires visual experience, but the neural circuits and plasticity mechanisms that are responsible for this developmental transition are unknown. To gain insight into the mechanisms that could underlie experience-dependent increases in selectivity, we explored families of cortical amplifier models that enhance weakly biased feedforward signals. Here we focused exclusively on possible contributions of cortico-cortical connections and took feedforward input to be constant. We modeled pairs of interconnected columns that received equal and oppositely biased inputs. In a single-element model of cortical columns, we found two ways that cortical columns could receive biased feedforward input and exhibit strong but unselective responses to stimuli: 1) within-column recurrent excitatory connections could be strong enough to amplify both strong and weak feedforward input, or 2) columns that received differently biased inputs could have strong excitatory cross-connections that destroy selectivity. A Hebbian plasticity rule combined with simulated experience with stimuli weakened these strong cross-connections across cortical columns, allowing the individual columns to respond selectively to their biased inputs. In a model that included both excitatory and inhibitory neurons in each column, an additional means of obtaining selectivity through the cortical circuit was uncovered: cross-column suppression of inhibition-stabilized networks. When each column operated as an inhibition-stabilized network, cross-column excitation onto inhibitory neurons forced competition between the columns but in a manner that did not involve strong null-direction inhibition, consistent with experimental measurements of direction selectivity in visual cortex. Experimental predictions of these possible contributions of cortical circuits are discussed.NEW & NOTEWORTHY Sensory circuits are initially constructed via mechanisms that are independent of sensory experience, but later refinement requires experience. We constructed models of how circuits that receive biased feedforward inputs can be initially unselective and then be modified by experience and plasticity so that the resulting circuit exhibits increased selectivity. We propose that neighboring cortical columns may initially exhibit coupling that is too strong for selectivity. Experience-dependent mechanisms decrease this coupling so individual columns can exhibit selectivity.
Collapse
Affiliation(s)
- Ian K Christie
- Department of Biology, Brandeis University, Waltham, Massachusetts.,Volen National Center for Complex Systems, Brandeis University, Waltham, Massachusetts; and
| | - Paul Miller
- Department of Biology, Brandeis University, Waltham, Massachusetts.,Volen National Center for Complex Systems, Brandeis University, Waltham, Massachusetts; and.,Sloan-Swartz Center for Theoretical Neurobiology, Brandeis University, Waltham, Massachusetts
| | - Stephen D Van Hooser
- Department of Biology, Brandeis University, Waltham, Massachusetts; .,Volen National Center for Complex Systems, Brandeis University, Waltham, Massachusetts; and.,Sloan-Swartz Center for Theoretical Neurobiology, Brandeis University, Waltham, Massachusetts
| |
Collapse
|
24
|
Dumitrescu AS, Evans MD, Grubb MS. Evaluating Tools for Live Imaging of Structural Plasticity at the Axon Initial Segment. Front Cell Neurosci 2016; 10:268. [PMID: 27932952 PMCID: PMC5120105 DOI: 10.3389/fncel.2016.00268] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2016] [Accepted: 11/04/2016] [Indexed: 11/20/2022] Open
Abstract
The axon initial segment (AIS) is a specialized neuronal compartment involved in the maintenance of axo-dendritic polarity and in the generation of action potentials. It is also a site of significant structural plasticity—manipulations of neuronal activity in vitro and in vivo can produce changes in AIS position and/or size that are associated with alterations in intrinsic excitability. However, to date all activity-dependent AIS changes have been observed in experiments carried out on fixed samples, offering only a snapshot, population-wide view of this form of plasticity. To extend these findings by following morphological changes at the AIS of individual neurons requires reliable means of labeling the structure in live preparations. Here, we assessed five different immunofluorescence-based and genetically-encoded tools for live-labeling the AIS of dentate granule cells (DGCs) in dissociated hippocampal cultures. We found that an antibody targeting the extracellular domain of neurofascin provided accurate live label of AIS structure at baseline, but could not follow rapid activity-dependent changes in AIS length. Three different fusion constructs of GFP with full-length AIS proteins also proved unsuitable: while neurofascin-186-GFP and NaVβ4-GFP did not localize to the AIS in our experimental conditions, overexpressing 270kDa-AnkyrinG-GFP produced abnormally elongated AISs in mature neurons. In contrast, a genetically-encoded construct consisting of a voltage-gated sodium channel intracellular domain fused to yellow fluorescent protein (YFP-NaVII–III) fulfilled all of our criteria for successful live AIS label: this construct specifically localized to the AIS, accurately revealed plastic changes at the structure within hours, and, crucially, did not alter normal cell firing properties. We therefore recommend this probe for future studies of live AIS plasticity in vitro and in vivo.
Collapse
Affiliation(s)
- Adna S Dumitrescu
- Centre for Developmental Neurobiology, King's College London London, UK
| | - Mark D Evans
- Centre for Developmental Neurobiology, King's College London London, UK
| | - Matthew S Grubb
- Centre for Developmental Neurobiology, King's College London London, UK
| |
Collapse
|
25
|
Genetically Encoded Voltage Indicators: Opportunities and Challenges. J Neurosci 2016; 36:9977-89. [PMID: 27683896 DOI: 10.1523/jneurosci.1095-16.2016] [Citation(s) in RCA: 103] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2016] [Accepted: 07/25/2016] [Indexed: 11/21/2022] Open
Abstract
UNLABELLED A longstanding goal in neuroscience is to understand how spatiotemporal patterns of neuronal electrical activity underlie brain function, from sensory representations to decision making. An emerging technology for monitoring electrical dynamics, voltage imaging using genetically encoded voltage indicators (GEVIs), couples the power of genetics with the advantages of light. Here, we review the properties that determine indicator performance and applicability, discussing both recent progress and technical limitations. We then consider GEVI applications, highlighting studies that have already deployed GEVIs for biological discovery. We also examine which classes of biological questions GEVIs are primed to address and which ones are beyond their current capabilities. As GEVIs are further developed, we anticipate that they will become more broadly used by the neuroscience community to eavesdrop on brain activity with unprecedented spatiotemporal resolution. SIGNIFICANCE STATEMENT Genetically encoded voltage indicators are engineered light-emitting protein sensors that typically report neuronal voltage dynamics as changes in brightness. In this review, we systematically discuss the current state of this emerging method, considering both its advantages and limitations for imaging neural activity. We also present recent applications of this technology and discuss what is feasible now and what we anticipate will become possible with future indicator development. This review will inform neuroscientists of recent progress in the field and help potential users critically evaluate the suitability of genetically encoded voltage indicator imaging to answer their specific biological questions.
Collapse
|
26
|
Klapper SD, Swiersy A, Bamberg E, Busskamp V. Biophysical Properties of Optogenetic Tools and Their Application for Vision Restoration Approaches. Front Syst Neurosci 2016; 10:74. [PMID: 27642278 PMCID: PMC5009148 DOI: 10.3389/fnsys.2016.00074] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2016] [Accepted: 08/17/2016] [Indexed: 11/13/2022] Open
Abstract
Optogenetics is the use of genetically encoded light-activated proteins to manipulate cells in a minimally invasive way using light. The most prominent example is channelrhodopsin-2 (ChR2), which allows the activation of electrically excitable cells via light-dependent depolarization. The combination of ChR2 with hyperpolarizing-light-driven ion pumps such as the Cl(-) pump halorhodopsin (NpHR) enables multimodal remote control of neuronal cells in culture, tissue, and living animals. Very soon, it became obvious that this method offers a chance of gene therapy for many diseases affecting vision. Here, we will give a brief introduction to retinal function and retinal diseases; optogenetic vision restoration strategies will be highlighted. We will discuss the functional and structural properties of rhodopsin-based optogenetic tools and analyze the potential for the application of vision restoration.
Collapse
Affiliation(s)
- Simon D Klapper
- Center for Regenerative Therapies Dresden, Technische Universität Dresden Dresden, Germany
| | - Anka Swiersy
- Center for Regenerative Therapies Dresden, Technische Universität Dresden Dresden, Germany
| | - Ernst Bamberg
- Max Planck Institute of Biophysics Frankfurt, Germany
| | - Volker Busskamp
- Center for Regenerative Therapies Dresden, Technische Universität Dresden Dresden, Germany
| |
Collapse
|
27
|
Baker CA, Elyada YM, Parra A, Bolton MM. Cellular resolution circuit mapping with temporal-focused excitation of soma-targeted channelrhodopsin. eLife 2016; 5. [PMID: 27525487 PMCID: PMC5001837 DOI: 10.7554/elife.14193] [Citation(s) in RCA: 97] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2016] [Accepted: 08/14/2016] [Indexed: 12/18/2022] Open
Abstract
We describe refinements in optogenetic methods for circuit mapping that enable measurements of functional synaptic connectivity with single-neuron resolution. By expanding a two-photon beam in the imaging plane using the temporal focusing method and restricting channelrhodopsin to the soma and proximal dendrites, we are able to reliably evoke action potentials in individual neurons, verify spike generation with GCaMP6s, and determine the presence or absence of synaptic connections with patch-clamp electrophysiological recording.
Collapse
Affiliation(s)
- Christopher A Baker
- Disorders of Neural Circuit Function, Max Planck Florida Institute for Neuroscience, Jupiter, United States
| | - Yishai M Elyada
- Functional Architecture of the Cerebral Cortex, Max Planck Florida Institute for Neuroscience, Jupiter, United States
| | - Andres Parra
- Functional Architecture of the Cerebral Cortex, Max Planck Florida Institute for Neuroscience, Jupiter, United States
| | - M McLean Bolton
- Disorders of Neural Circuit Function, Max Planck Florida Institute for Neuroscience, Jupiter, United States
| |
Collapse
|
28
|
LSPS/Optogenetics to Improve Synaptic Connectivity Mapping: Unmasking the Role of Basket Cell-Mediated Feedforward Inhibition. eNeuro 2016; 3:eN-MNT-0142-15. [PMID: 27517089 PMCID: PMC4976301 DOI: 10.1523/eneuro.0142-15.2016] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2015] [Revised: 06/28/2016] [Accepted: 07/15/2016] [Indexed: 12/20/2022] Open
Abstract
Neocortical pyramidal cells (PYRs) receive synaptic inputs from many types of GABAergic interneurons. Connections between parvalbumin (PV)-positive, fast-spiking interneurons (“PV cells”) and PYRs are characterized by perisomatic synapses and high-amplitude, short-latency IPSCs. Here, we present novel methods to study the functional influence of PV cells on layer 5 PYRs using optogenetics combined with laser-scanning photostimulation (LSPS). First, we examined the strength and spatial distribution of PV-to-PYR inputs. To that end, the fast channelrhodopsin variant AAV5-EF1α-DIO-hChR2(E123T)-eYFP (ChETA) was expressed in PV cells in somatosensory cortex of mice using an adeno-associated virus-based viral construct. Focal blue illumination (100–150 µm half-width) was directed through the microscope objective to excite PV cells along a spatial grid covering layers 2–6, while IPSCs were recorded in layer 5 PYRs. The resulting optogenetic input maps showed evoked PV cell inputs originating from an ∼500-μm-diameter area surrounding the recorded PYR. Evoked IPSCs had the short-latency/high-amplitude characteristic of PV cell inputs. Second, we investigated how PV cell activity modulates PYR output in response to synaptic excitation. We expressed halorhodopsin (eNpHR3.0) in PV cells using the same strategy as for ChETA. Yellow illumination hyperpolarized eNpHR3.0-expressing PV cells, effectively preventing action potential generation and thus decreasing the inhibition of downstream targets. Synaptic input maps onto layer 5 PYRs were acquired using standard glutamate-photolysis LSPS either with or without full-field yellow illumination to silence PV cells. The resulting IPSC input maps selectively lacked short-latency perisomatic inputs, while EPSC input maps showed increased connectivity, particularly from upper layers. This indicates that glutamate uncaging LSPS-based excitatory synaptic maps will consistently underestimate connectivity.
Collapse
|
29
|
Pabst M, Braganza O, Dannenberg H, Hu W, Pothmann L, Rosen J, Mody I, van Loo K, Deisseroth K, Becker AJ, Schoch S, Beck H. Astrocyte Intermediaries of Septal Cholinergic Modulation in the Hippocampus. Neuron 2016; 90:853-65. [PMID: 27161528 DOI: 10.1016/j.neuron.2016.04.003] [Citation(s) in RCA: 83] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2014] [Revised: 07/09/2015] [Accepted: 03/14/2016] [Indexed: 01/17/2023]
Abstract
The neurotransmitter acetylcholine, derived from the medial septum/diagonal band of Broca complex, has been accorded an important role in hippocampal learning and memory processes. However, the precise mechanisms whereby acetylcholine released from septohippocampal cholinergic neurons acts to modulate hippocampal microcircuits remain unknown. Here, we show that acetylcholine release from cholinergic septohippocampal projections causes a long-lasting GABAergic inhibition of hippocampal dentate granule cells in vivo and in vitro. This inhibition is caused by cholinergic activation of hilar astrocytes, which provide glutamatergic excitation of hilar inhibitory interneurons. These results demonstrate that acetylcholine release can cause slow inhibition of principal neuronal activity via astrocyte intermediaries.
Collapse
Affiliation(s)
- Milan Pabst
- Laboratory for Experimental Epileptology and Cognition Research, Department of Epileptology, University of Bonn Medical Center, Sigmund-Freud-Strasse 25, 53105 Bonn, Germany
| | - Oliver Braganza
- Laboratory for Experimental Epileptology and Cognition Research, Department of Epileptology, University of Bonn Medical Center, Sigmund-Freud-Strasse 25, 53105 Bonn, Germany
| | - Holger Dannenberg
- Laboratory for Experimental Epileptology and Cognition Research, Department of Epileptology, University of Bonn Medical Center, Sigmund-Freud-Strasse 25, 53105 Bonn, Germany
| | - Wen Hu
- Laboratory for Experimental Epileptology and Cognition Research, Department of Epileptology, University of Bonn Medical Center, Sigmund-Freud-Strasse 25, 53105 Bonn, Germany
| | - Leonie Pothmann
- Laboratory for Experimental Epileptology and Cognition Research, Department of Epileptology, University of Bonn Medical Center, Sigmund-Freud-Strasse 25, 53105 Bonn, Germany
| | - Jurij Rosen
- Laboratory for Experimental Epileptology and Cognition Research, Department of Epileptology, University of Bonn Medical Center, Sigmund-Freud-Strasse 25, 53105 Bonn, Germany
| | - Istvan Mody
- Department of Neurology, UCLA School of Medicine, 635 Charles Young Drive South, Los Angeles, CA 90095, USA
| | - Karen van Loo
- Section for Translational Epilepsy Research, Department of Neuropathology, University of Bonn Medical Center, Sigmund-Freud-Strasse 25, 53105 Bonn, Germany
| | - Karl Deisseroth
- Department of Bioengineering, Stanford University and Howard Hughes Medical Institute, 318 Campus Drive, Stanford, CA 94305, USA
| | - Albert J Becker
- Section for Translational Epilepsy Research, Department of Neuropathology, University of Bonn Medical Center, Sigmund-Freud-Strasse 25, 53105 Bonn, Germany
| | - Susanne Schoch
- Section for Translational Epilepsy Research, Department of Neuropathology, University of Bonn Medical Center, Sigmund-Freud-Strasse 25, 53105 Bonn, Germany
| | - Heinz Beck
- Laboratory for Experimental Epileptology and Cognition Research, Department of Epileptology, University of Bonn Medical Center, Sigmund-Freud-Strasse 25, 53105 Bonn, Germany; German Center for Neurodegenerative Diseases (DZNE), Sigmund-Freud-Strasse 25, 53105 Bonn, Germany.
| |
Collapse
|
30
|
Pulizzi R, Musumeci G, Van den Haute C, Van De Vijver S, Baekelandt V, Giugliano M. Brief wide-field photostimuli evoke and modulate oscillatory reverberating activity in cortical networks. Sci Rep 2016; 6:24701. [PMID: 27099182 PMCID: PMC4838830 DOI: 10.1038/srep24701] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2015] [Accepted: 04/04/2016] [Indexed: 01/18/2023] Open
Abstract
Cell assemblies manipulation by optogenetics is pivotal to advance neuroscience and neuroengineering. In in vivo applications, photostimulation often broadly addresses a population of cells simultaneously, leading to feed-forward and to reverberating responses in recurrent microcircuits. The former arise from direct activation of targets downstream, and are straightforward to interpret. The latter are consequence of feedback connectivity and may reflect a variety of time-scales and complex dynamical properties. We investigated wide-field photostimulation in cortical networks in vitro, employing substrate-integrated microelectrode arrays and long-term cultured neuronal networks. We characterized the effect of brief light pulses, while restricting the expression of channelrhodopsin to principal neurons. We evoked robust reverberating responses, oscillating in the physiological gamma frequency range, and found that such a frequency could be reliably manipulated varying the light pulse duration, not its intensity. By pharmacology, mathematical modelling, and intracellular recordings, we conclude that gamma oscillations likely emerge as in vivo from the excitatory-inhibitory interplay and that, unexpectedly, the light stimuli transiently facilitate excitatory synaptic transmission. Of relevance for in vitro models of (dys)functional cortical microcircuitry and in vivo manipulations of cell assemblies, we give for the first time evidence of network-level consequences of the alteration of synaptic physiology by optogenetics.
Collapse
Affiliation(s)
- Rocco Pulizzi
- Theoretical Neurobiology &Neuroengineering, University of Antwerp, Antwerp, Belgium
| | - Gabriele Musumeci
- Theoretical Neurobiology &Neuroengineering, University of Antwerp, Antwerp, Belgium
| | - Chris Van den Haute
- Laboratory of Neurobiology and Gene Therapy, Katholieke Universiteit Leuven, Leuven, Belgium.,Leuven Viral Vector Core, Katholieke Universiteit Leuven, Leuven, Belgium
| | | | - Veerle Baekelandt
- Laboratory of Neurobiology and Gene Therapy, Katholieke Universiteit Leuven, Leuven, Belgium
| | - Michele Giugliano
- Theoretical Neurobiology &Neuroengineering, University of Antwerp, Antwerp, Belgium.,Department of Computer Science, University of Sheffield, S1 4DP Sheffield, UK.,Laboratory of Neural Microcircuitry, Brain Mind Institute, EPFL, CH-1015 Lausanne, Switzerland
| |
Collapse
|
31
|
Abstract
After the discovery of Channelrhodopsin, a light-gated ion channel, only a few people saw the diverse range of applications for such a protein. Now, more than 10 years later Channelrhodopsins have become widely accepted as the ultimate tool to control the membrane potential of excitable cells via illumination. The demand for more application-specific Channelrhodopsin variants started a race between protein engineers to design improved variants. Even though many engineered variants have undisputable advantages compared to wild-type variants, many users are alienated by the tremendous amount of new variants and their perplexing names. Here, we review new variants whose efficacy has already been proven in neurophysiological experiments, or variants which are likely to extend the optogenetic toolbox. Variants are described based on their mechanistic and operational properties in terms of expression, kinetics, ion selectivity, and wavelength responsivity.
Collapse
Affiliation(s)
- Jonas Wietek
- Experimental Biophysics, Humboldt University Berlin, Invalidenstrasse 42, 10115, Berlin, Germany
| | - Matthias Prigge
- Department of Neurobiology, Weizmann Institute of Science, Herzel 234, 76100, Rehovot, Israel.
| |
Collapse
|
32
|
Roy A, Osik JJ, Ritter NJ, Wang S, Shaw JT, Fiser J, Van Hooser SD. Optogenetic spatial and temporal control of cortical circuits on a columnar scale. J Neurophysiol 2015; 115:1043-62. [PMID: 26631152 DOI: 10.1152/jn.00960.2015] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2015] [Accepted: 11/28/2015] [Indexed: 11/22/2022] Open
Abstract
Many circuits in the mammalian brain are organized in a topographic or columnar manner. These circuits could be activated-in ways that reveal circuit function or restore function after disease-by an artificial stimulation system that is capable of independently driving local groups of neurons. Here we present a simple custom microscope called ProjectorScope 1 that incorporates off-the-shelf parts and a liquid crystal display (LCD) projector to stimulate surface brain regions that express channelrhodopsin-2 (ChR2). In principle, local optogenetic stimulation of the brain surface with optical projection systems might not produce local activation of a highly interconnected network like the cortex, because of potential stimulation of axons of passage or extended dendritic trees. However, here we demonstrate that the combination of virally mediated ChR2 expression levels and the light intensity of ProjectorScope 1 is capable of producing local spatial activation with a resolution of ∼200-300 μm. We use the system to examine the role of cortical activity in the experience-dependent emergence of motion selectivity in immature ferret visual cortex. We find that optogenetic cortical activation alone-without visual stimulation-is sufficient to produce increases in motion selectivity, suggesting the presence of a sharpening mechanism that does not require precise spatiotemporal activation of the visual system. These results demonstrate that optogenetic stimulation can sculpt the developing brain.
Collapse
Affiliation(s)
- Arani Roy
- Department of Biology, Brandeis University, Waltham, Massachusetts; Volen Center for Complex Systems, Brandeis University, Waltham, Massachusetts
| | - Jason J Osik
- Department of Biology, Brandeis University, Waltham, Massachusetts; Volen Center for Complex Systems, Brandeis University, Waltham, Massachusetts
| | - Neil J Ritter
- Department of Biology, Brandeis University, Waltham, Massachusetts; Volen Center for Complex Systems, Brandeis University, Waltham, Massachusetts
| | - Shen Wang
- Department of Biology, Brandeis University, Waltham, Massachusetts; Volen Center for Complex Systems, Brandeis University, Waltham, Massachusetts
| | - James T Shaw
- Department of Biology, Brandeis University, Waltham, Massachusetts
| | - József Fiser
- Volen Center for Complex Systems, Brandeis University, Waltham, Massachusetts; Sloan-Swartz Center for Theoretical Neurobiology, Brandeis University, Waltham, Massachusetts; and Department of Cognitive Sciences, Central European University, Budapest, Hungary
| | - Stephen D Van Hooser
- Department of Biology, Brandeis University, Waltham, Massachusetts; Volen Center for Complex Systems, Brandeis University, Waltham, Massachusetts; Sloan-Swartz Center for Theoretical Neurobiology, Brandeis University, Waltham, Massachusetts; and
| |
Collapse
|
33
|
Optogenetic acidification of synaptic vesicles and lysosomes. Nat Neurosci 2015; 18:1845-1852. [PMID: 26551543 PMCID: PMC4869830 DOI: 10.1038/nn.4161] [Citation(s) in RCA: 96] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2015] [Accepted: 10/08/2015] [Indexed: 12/12/2022]
Abstract
Acidification is required for the function of many intracellular organelles, but methods
to acutely manipulate their intraluminal pH have not been available. Here we
present a targeting strategy to selectively express the light-driven proton pump
Arch3 on synaptic vesicles. Our new tool, pHoenix, can functionally replace
endogenous proton pumps, enabling optogenetic control of vesicular acidification
and neurotransmitter accumulation. Under physiological conditions, glutamatergic
vesicles are nearly full, as additional vesicle acidification with pHoenix only
slightly increased the quantal size. By contrast, we found that incompletely
filled vesicles exhibited a lower release probability than full vesicles,
suggesting preferential exocytosis of vesicles with high transmitter content.
Our subcellular targeting approach can be transferred to other organelles, as
demonstrated for a pHoenix variant that allows light-activated acidification of
lysosomes.
Collapse
|
34
|
Targeted Expression of Channelrhodopsin-2 to the Axon Initial Segment Alters the Temporal Firing Properties of Retinal Ganglion Cells. PLoS One 2015; 10:e0142052. [PMID: 26536117 PMCID: PMC4633179 DOI: 10.1371/journal.pone.0142052] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2015] [Accepted: 10/17/2015] [Indexed: 01/09/2023] Open
Abstract
The axon initial segment (AIS) is essential for initiating action potentials and maintaining neuronal excitability in axon-bearing neurons in the CNS. There is increasing interest in the targeting of optogenetic tools to subcellular compartments, including the AIS, to gain precise control of neuronal activity for basic research and clinical applications. In particular, targeted expression of optogenetic tools in retinal ganglion cells (RGCs) has been explored as an approach for restoring vision after photoreceptor degeneration. Thus, understanding the effects of such targeting on spiking abilities and/or patterns is important. Here, we examined the effects of recombinant adeno-associated virus (rAAV)-mediated targeted expression of channelrhodopsin-2 (ChR2)-GFP with a NaV channel motif in mouse RGCs. We found that this targeted expression disrupted NaV channel clustering at the AIS and converted the spike firing patterns of RGCs from sustained to transient. Our results suggest that the clustering of membrane channels, including NaV channels, at the AIS is important for the ability of RGCs to generate sustained spike firing. Additionally, the targeting of optogenetic tools to the AIS with the NaV channel motif may offer a way to create transient light responses in RGCs for vision restoration.
Collapse
|
35
|
Hannon E, Chand AN, Evans MD, Wong CCY, Grubb MS, Mill J. A role for Ca V1 and calcineurin signaling in depolarization-induced changes in neuronal DNA methylation. ACTA ACUST UNITED AC 2015; 3:1-6. [PMID: 26702400 PMCID: PMC4659419 DOI: 10.1016/j.nepig.2015.06.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2015] [Revised: 06/22/2015] [Accepted: 06/23/2015] [Indexed: 01/08/2023]
Abstract
Direct manipulations of neuronal activity have been shown to induce changes in DNA methylation (DNAm), although little is known about the cellular signaling pathways involved. Using reduced representation bisulfite sequencing, we identify DNAm changes associated with moderate chronic depolarization in dissociated rat hippocampal cultures. Consistent with previous findings, these changes occurred primarily in the vicinity of loci implicated in neuronal function, being enriched in intergenic regions and underrepresented in CpG-rich promoter regulatory regions. We subsequently used 2 pharmacological interventions (nifedipine and FK-506) to test whether the identified changes depended on 2 interrelated signaling pathways known to mediate multiple forms of neuronal plasticity. Both pharmacological manipulations had notable effects on the extent and magnitude of depolarization-induced DNAm changes indicating that a high proportion of activity-induced changes are likely to be mediated by calcium entry through L-type CaV1 channels and/or downstream signaling via the calcium-dependent phosphatase calcineurin.
Collapse
Affiliation(s)
- Eilis Hannon
- University of Exeter Medical School, University of Exeter, Exeter, UK
| | - Annisa N Chand
- MRC Centre for Developmental Neurobiology, King's College London, London, UK
| | - Mark D Evans
- MRC Centre for Developmental Neurobiology, King's College London, London, UK
| | - Chloe C Y Wong
- MRC Social, Genetic & Developmental Psychiatry Centre, Institute of Psychiatry, Psychology & Neuroscience, King's College London, London UK
| | - Matthew S Grubb
- MRC Centre for Developmental Neurobiology, King's College London, London, UK
| | - Jonathan Mill
- University of Exeter Medical School, University of Exeter, Exeter, UK ; MRC Social, Genetic & Developmental Psychiatry Centre, Institute of Psychiatry, Psychology & Neuroscience, King's College London, London UK
| |
Collapse
|
36
|
Jeschke M, Moser T. Considering optogenetic stimulation for cochlear implants. Hear Res 2015; 322:224-34. [PMID: 25601298 DOI: 10.1016/j.heares.2015.01.005] [Citation(s) in RCA: 48] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/15/2014] [Revised: 12/09/2014] [Accepted: 01/08/2015] [Indexed: 02/04/2023]
Abstract
Electrical cochlear implants are by far the most successful neuroprostheses and have been implanted in over 300,000 people worldwide. Cochlear implants enable open speech comprehension in most patients but are limited in providing music appreciation and speech understanding in noisy environments. This is generally considered to be due to low frequency resolution as a consequence of wide current spread from stimulation contacts. Accordingly, the number of independently usable stimulation channels is limited to less than a dozen. As light can be conveniently focused, optical stimulation might provide an alternative approach to cochlear implants with increased number of independent stimulation channels. Here, we focus on summarizing recent work on optogenetic stimulation as one way to develop optical cochlear implants. We conclude that proof of principle has been presented for optogenetic stimulation of the cochlea and central auditory neurons in rodents as well as for the technical realization of flexible μLED-based multichannel cochlear implants. Still, much remains to be done in order to advance the technique for auditory research and even more for eventual clinical translation. This article is part of a Special Issue entitled <Lasker Award>.
Collapse
Affiliation(s)
- Marcus Jeschke
- Institute for Auditory Neuroscience, University Medical Center Goettingen, Goettingen, Germany; Auditory Neuroscience Group, German Primate Center, Goettingen, Germany.
| | - Tobias Moser
- Institute for Auditory Neuroscience, University Medical Center Goettingen, Goettingen, Germany; Auditory Neuroscience Group, German Primate Center, Goettingen, Germany; Bernstein Focus for Neurotechnology, University of Göttingen, Goettingen, Germany; Collaborative Research Center 889, University of Goettingen Medical Center, Goettingen, Germany; Center for Nanoscale Microscopy and Molecular Physiology of the Brain, University of Goettingen, Goettingen, Germany.
| |
Collapse
|
37
|
Optical dissection of brain circuits with patterned illumination through the phase modulation of light. J Neurosci Methods 2014; 241:66-77. [PMID: 25497065 DOI: 10.1016/j.jneumeth.2014.12.002] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2014] [Revised: 11/28/2014] [Accepted: 12/02/2014] [Indexed: 12/31/2022]
Abstract
Brain function relies on electrical signaling among ensembles of neurons. These signals are encoded in space - neurons are organized in complex three-dimensional networks - and in time-cells generate electrical signals on a millisecond scale. How the spatial and temporal structure of these signals controls higher brain functions is largely unknown. The recent advent of novel molecules that manipulate and monitor electrical activity in genetically identified cells provides, for the first time, the ability to causally test the contribution of specific cell subpopulations in these complex brain phenomena. However, most of the commonly used approaches are limited in their ability to illuminate brain tissue with high spatial and temporal precision. In this review article, we focus on one technique, patterned illumination through the phase modulation of light using liquid crystal spatial light modulators (LC-SLMs), which has the potential to overcome some of the major limitations of current experimental approaches.
Collapse
|
38
|
Beyeler A, Eckhardt CA, Tye KM. Deciphering Memory Function with Optogenetics. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2014; 122:341-90. [DOI: 10.1016/b978-0-12-420170-5.00012-x] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
|
39
|
rAAV-mediated subcellular targeting of optogenetic tools in retinal ganglion cells in vivo. PLoS One 2013; 8:e66332. [PMID: 23799092 PMCID: PMC3683040 DOI: 10.1371/journal.pone.0066332] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2013] [Accepted: 05/03/2013] [Indexed: 01/01/2023] Open
Abstract
Expression of optogenetic tools in surviving inner retinal neurons to impart retinal light sensitivity has been a new strategy for restoring vision after photoreceptor degeneration. One potential approach for restoring retinal light sensitivity after photoreceptor degeneration is to express optogenetic tools in retinal ganglion cells (RGCs). For this approach, restoration of ON and OFF center-surround receptive fields in RGCs, a key feature of visual information processing, may be important. A possible solution is to differentially express depolarizing and hyperpolarizing optogenetic tools, such as channelrhodopsin-2 and halorhodopsin, to the center and peripheral regions of the RGC dendritic field by using protein targeting motifs. Recombinant adeno-associated virus (rAAV) vectors have proven to be a powerful vehicle for in vitro and in vivo gene delivery, including in the retina. Therefore, the search for protein targeting motifs that can achieve rAAV-mediated subcellular targeted expression would be particularly valuable for developing therapeutic applications. In this study, we identified two protein motifs that are suitable for rAAV-mediated subcellular targeting for generating center-surround receptive fields while reducing the axonal expression in RGCs. Resulting morphological dendritic field and physiological response field by center-targeting were significantly smaller than those produced by surround-targeting. rAAV motif-mediated protein targeting could also be a valuable tool for studying physiological function and clinical applications in other areas of the central nervous system.
Collapse
|
40
|
Lee S, Kwag J. M-channels modulate the intrinsic excitability and synaptic responses of layer 2/3 pyramidal neurons in auditory cortex. Biochem Biophys Res Commun 2012; 426:448-53. [PMID: 22925893 DOI: 10.1016/j.bbrc.2012.08.057] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2012] [Accepted: 08/13/2012] [Indexed: 11/18/2022]
Abstract
Neurons in the auditory cortex are believed to utilize temporal patterns of neural activity to accurately process auditory information but the intrinsic neuronal mechanism underlying the control of auditory neural activity is not known. The slowly activating, persistent K(+) channel, also called M-channel that belongs to the Kv7 family, is already known to be important in regulating subthreshold neural excitability and synaptic summation in neocortical and hippocampal pyramidal neurons. However, its functional role in the primary auditory cortex (A1) has never been characterized. In this study, we investigated the roles of M-channels on neuronal excitability, short-term plasticity, and synaptic summation of A1 layer 2/3 regular spiking pyramidal neurons with whole-cell current-clamp recordings in vitro. We found that blocking M-channels with a selective M-channel blocker, XE991, significantly increased neural excitability of A1 layer 2/3 pyramidal neurons. Furthermore, M-channels controled synaptic responses of intralaminar-evoked excitatory postsynaptic potentials (EPSPs); XE991 significantly increased EPSP amplitude, decreased the rate of short-term depression, and increased the synaptic summation. These results suggest that M-channels are involved in controlling spike output patterns and synaptic responses of A1 layer 2/3 pyramidal neurons, which would have important implications in auditory information processing.
Collapse
Affiliation(s)
- Sujeong Lee
- Department of Brain and Cognitive Engineering, Korea University, Seoul, Republic of Korea
| | | |
Collapse
|
41
|
Piñol RA, Bateman R, Mendelowitz D. Optogenetic approaches to characterize the long-range synaptic pathways from the hypothalamus to brain stem autonomic nuclei. J Neurosci Methods 2012; 210:238-46. [PMID: 22890236 DOI: 10.1016/j.jneumeth.2012.07.022] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2011] [Revised: 07/12/2012] [Accepted: 07/19/2012] [Indexed: 01/23/2023]
Abstract
Recent advances in optogenetic methods demonstrate the feasibility of selective photoactivation at the soma of neurons that express channelrhodopsin-2 (ChR2), but a comprehensive evaluation of different methods to selectively evoke transmitter release from distant synapses using optogenetic approaches is needed. Here we compared different lentiviral vectors, with sub-population-specific and strong promoters, and transgenic methods to express and photostimulate ChR2 in the long-range projections of paraventricular nucleus of the hypothalamus (PVN) neurons to brain stem cardiac vagal neurons (CVNs). Using PVN subpopulation-specific promoters for vasopressin and oxytocin, we were able to depolarize the soma of these neurons upon photostimulation, but these promoters were not strong enough to drive sufficient expression for optogenetic stimulation and synaptic release from the distal axons. However, utilizing the synapsin promoter photostimulation of distal PVN axons successfully evoked glutamatergic excitatory post-synaptic currents in CVNs. Employing the Cre/loxP system, using the Sim-1 Cre-driver mouse line, we found that the Rosa-CAG-LSL-ChR2-EYFP Cre-responder mice expressed higher levels of ChR2 than the Rosa-CAG-LSL-ChR2-tdTomato line in the PVN, judged by photo-evoked currents at the soma. However, neither was able to drive sufficient expression to observe and photostimulate the long-range projections to brainstem autonomic regions. We conclude that a viral vector approach with a strong promoter is required for successful optogenetic stimulation of distal axons to evoke transmitter release in pre-autonomic PVN neurons. This approach can be very useful to study important hypothalamus-brainstem connections, and can be easily modified to selectively activate other long-range projections within the brain.
Collapse
Affiliation(s)
- Ramón A Piñol
- Department of Pharmacology and Physiology, The George Washington University, 2300 Eye Street NW, Washington, DC 20037, USA.
| | | | | |
Collapse
|
42
|
Foutz TJ, Arlow RL, McIntyre CC. Theoretical principles underlying optical stimulation of a channelrhodopsin-2 positive pyramidal neuron. J Neurophysiol 2012; 107:3235-45. [PMID: 22442566 DOI: 10.1152/jn.00501.2011] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Optogenetics is an emerging field of neuromodulation that permits scaled, millisecond temporal control of the membrane dynamics of genetically targeted cells using light. Optogenetic technology has revolutionized neuroscience research; however, numerous biophysical questions remain on the optical and neuronal factors impacting the modulation of neural activity with photon-sensitive ion channels. To begin to address such questions, we developed a computational tool to explore the underlying principles of optogenetic neural stimulation. This "light-neuron" model consists of theoretical representations of the light dynamics generated by a fiber optic in brain tissue, coupled to a multicompartment cable model of a cortical pyramidal neuron embedded with channelrhodopsin-2 (ChR2) membrane dynamics. Simulations revealed that the large energies required to generate an action potential are primarily due to the limited conductivity of ChR2, and that the major determinants of stimulation threshold are the surface area of illuminated cell membrane and proximity to the light source. Our results predict that the activation threshold is sensitive to many of the properties of ChR2 (density, conductivity, and kinetics), tissue medium (scattering and absorbance), and the fiber-optic light source (diameter and numerical aperture). We also illustrate the impact of redistributing the ChR2 expression density (uniform vs. nonuniform) on the activation threshold. The model system developed in this study represents a scientific instrument to characterize the effects of optogenetic neuromodulation, as well as an engineering design tool to help guide future development of optogenetic technology.
Collapse
Affiliation(s)
- Thomas J Foutz
- Cleveland Clinic Foundation, Dept. of Biomedical Engineering, Cleveland, OH 44195, USA.
| | | | | |
Collapse
|
43
|
Histed MH, Ni AM, Maunsell JHR. Insights into cortical mechanisms of behavior from microstimulation experiments. Prog Neurobiol 2012; 103:115-30. [PMID: 22307059 DOI: 10.1016/j.pneurobio.2012.01.006] [Citation(s) in RCA: 80] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2011] [Revised: 01/06/2012] [Accepted: 01/19/2012] [Indexed: 11/15/2022]
Abstract
Even the simplest behaviors depend on a large number of neurons that are distributed across many brain regions. Because electrical microstimulation can change the activity of localized subsets of neurons, it has provided valuable evidence that specific neurons contribute to particular behaviors. Here we review what has been learned about cortical function from behavioral studies using microstimulation in animals and humans. Experiments that examine how microstimulation affects the perception of stimuli have shown that the effects of microstimulation are usually highly specific and can be related to the stimuli preferred by neurons at the stimulated site. Experiments that ask subjects to detect cortical microstimulation in the absence of other stimuli have provided further insights. Although subjects typically can detect microstimulation of primary sensory or motor cortex, they are generally unable to detect stimulation of most of cortex without extensive practice. With practice, however, stimulation of any part of cortex can become detected. These training effects suggest that some patterns of cortical activity cannot be readily accessed to guide behavior, but that the adult brain retains enough plasticity to learn to process novel patterns of neuronal activity arising anywhere in cortex.
Collapse
Affiliation(s)
- Mark H Histed
- Department of Neurobiology, Harvard Medical School, 220 Longwood Avenue, Boston, MA 02115, USA
| | | | | |
Collapse
|
44
|
|
45
|
Action potential generation at an axon initial segment-like process in the axonless retinal AII amacrine cell. J Neurosci 2011; 31:14654-9. [PMID: 21994381 DOI: 10.1523/jneurosci.1861-11.2011] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
In axon-bearing neurons, action potentials conventionally initiate at the axon initial segment (AIS) and are important for neuron excitability and cell-to-cell communication. However in axonless neurons, spike origin has remained unclear. Here we report in the axonless, spiking AII amacrine cell of the mouse retina a dendritic process sharing organizational and functional similarities with the AIS. This process was revealed through viral-mediated expression of channelrhodopsin-2-GFP with the AIS-targeting motif of sodium channels (Na(v)II-III). The AII processes showed clustering of voltage-gated Na+ channel 1.1 (Na(v)1.1) as well as AIS markers ankyrin-G and neurofascin. Furthermore, Na(v)II-III targeting disrupted Na(v)1.1 clustering in the AII process, which drastically decreased Na+ current and abolished the ability of the AII amacrine cell to generate spiking. Our findings indicate that, despite lacking an axon, spiking in the axonless neuron can originate at a specialized AIS-like process.
Collapse
|
46
|
Valley M, Wagner S, Gallarda BW, Lledo PM. Using affordable LED arrays for photo-stimulation of neurons. J Vis Exp 2011:3379. [PMID: 22127025 DOI: 10.3791/3379] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Standard slice electrophysiology has allowed researchers to probe individual components of neural circuitry by recording electrical responses of single cells in response to electrical or pharmacological manipulations(1,2). With the invention of methods to optically control genetically targeted neurons (optogenetics), researchers now have an unprecedented level of control over specific groups of neurons in the standard slice preparation. In particular, photosensitive channel rhodopsin-2 (ChR2) allows researchers to activate neurons with light(3,4). By combining careful calibration of LED-based photostimulation of ChR2 with standard slice electrophysiology, we are able to probe with greater detail the role of adult-born interneurons in the olfactory bulb, the first central relay of the olfactory system. Using viral expression of ChR2-YFP specifically in adult-born neurons, we can selectively control young adult-born neurons in a milieu of older and mature neurons. Our optical control uses a simple and inexpensive LED system, and we show how this system can be calibrated to understand how much light is needed to evoke spiking activity in single neurons. Hence, brief flashes of blue light can remotely control the firing pattern of ChR2-transduced newborn cells.
Collapse
Affiliation(s)
- Matthew Valley
- Laboratory for Perception and Memory, Institut Pasteur and Centre National de la Recherche Scientifique (CNRS)
| | | | | | | |
Collapse
|
47
|
Abstract
Genetically encoded, single-component optogenetic tools have made a significant impact on neuroscience, enabling specific modulation of selected cells within complex neural tissues. As the optogenetic toolbox contents grow and diversify, the opportunities for neuroscience continue to grow. In this review, we outline the development of currently available single-component optogenetic tools and summarize the application of various optogenetic tools in diverse model organisms.
Collapse
Affiliation(s)
- Lief Fenno
- Department of Bioengineering, Stanford University, Stanford, California 94305, USA
| | | | | |
Collapse
|
48
|
Peron S, Svoboda K. From cudgel to scalpel: toward precise neural control with optogenetics. Nat Methods 2010; 8:30-4. [PMID: 21191369 DOI: 10.1038/nmeth.f.325] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Affiliation(s)
- Simon Peron
- Howard Hughes Medical Institute Janelia Farm Research Campus, Ashburn, Virginia, USA
| | | |
Collapse
|