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Li D, Wang G, Werner R, Xie H, Guan JS, Hilgetag CC. Single Image-Based Vignetting Correction for Improving the Consistency of Neural Activity Analysis in 2-Photon Functional Microscopy. Front Neuroinform 2022; 15:674439. [PMID: 35069164 PMCID: PMC8766855 DOI: 10.3389/fninf.2021.674439] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2021] [Accepted: 12/01/2021] [Indexed: 12/04/2022] Open
Abstract
High-resolution functional 2-photon microscopy of neural activity is a cornerstone technique in current neuroscience, enabling, for instance, the image-based analysis of relations of the organization of local neuron populations and their temporal neural activity patterns. Interpreting local image intensity as a direct quantitative measure of neural activity presumes, however, a consistent within- and across-image relationship between the image intensity and neural activity, which may be subject to interference by illumination artifacts. In particular, the so-called vignetting artifact—the decrease of image intensity toward the edges of an image—is, at the moment, widely neglected in the context of functional microscopy analyses of neural activity, but potentially introduces a substantial center-periphery bias of derived functional measures. In the present report, we propose a straightforward protocol for single image-based vignetting correction. Using immediate-early gene-based 2-photon microscopic neural image data of the mouse brain, we show the necessity of correcting both image brightness and contrast to improve within- and across-image intensity consistency and demonstrate the plausibility of the resulting functional data.
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Affiliation(s)
- Dong Li
- Institute of Computational Neuroscience, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
- *Correspondence: Dong Li,
| | - Guangyu Wang
- School of Life Sciences and Technology, ShanghaiTech University, Shanghai, China
| | - René Werner
- Institute of Computational Neuroscience, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
- Center for Biomedical Artificial Intelligence (bAIome), University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Hong Xie
- Institute of Photonic Chips, University of Shanghai for Science and Technology, Shanghai, China
- School of Health Science and Engineering, University of Shanghai for Science and Technology, Shanghai, China
| | - Ji-Song Guan
- School of Life Sciences and Technology, ShanghaiTech University, Shanghai, China
- Institute of Psychology, Chinese Academy of Sciences, Beijing, China
| | - Claus C. Hilgetag
- Institute of Computational Neuroscience, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
- Center for Biomedical Artificial Intelligence (bAIome), University Medical Center Hamburg-Eppendorf, Hamburg, Germany
- Department of Health Sciences, Boston University, Boston, MA, United States
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2
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Cassel JC, Pereira de Vasconcelos A. Routes of the thalamus through the history of neuroanatomy. Neurosci Biobehav Rev 2021; 125:442-465. [PMID: 33676963 DOI: 10.1016/j.neubiorev.2021.03.001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2020] [Revised: 02/19/2021] [Accepted: 03/01/2021] [Indexed: 12/24/2022]
Abstract
The most distant roots of neuroanatomy trace back to antiquity, with the first human dissections, but no document which would identify the thalamus as a brain structure has reached us. Claudius Galenus (Galen) gave to the thalamus the name 'thalamus nervorum opticorum', but later on, other names were used (e.g., anchae, or buttocks-like). In 1543, Andreas Vesalius provided the first quality illustrations of the thalamus. During the 19th century, tissue staining techniques and ablative studies contributed to the breakdown of the thalamus into subregions and nuclei. The next step was taken using radiomarkers to identify connections in the absence of lesions. Anterograde and retrograde tracing methods arose in the late 1960s, supporting extension, revision, or confirmation of previously established knowledge. The use of the first viral tracers introduced a new methodological breakthrough in the mid-1970s. Another important step was supported by advances in neuroimaging of the thalamus in the 21th century. The current review follows the history of the thalamus through these technical revolutions from Antiquity to the present day.
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Affiliation(s)
- Jean-Christophe Cassel
- Laboratoire de Neurosciences Cognitives et Adaptatives, Université de Strasbourg, F-67000 Strasbourg, France; LNCA, UMR 7364 - CNRS, F-67000 Strasbourg, France.
| | - Anne Pereira de Vasconcelos
- Laboratoire de Neurosciences Cognitives et Adaptatives, Université de Strasbourg, F-67000 Strasbourg, France; LNCA, UMR 7364 - CNRS, F-67000 Strasbourg, France
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3
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Williams PDE, Verma S, Robertson AP, Martin RJ. Adapting techniques for calcium imaging in muscles of adult Brugia malayi. INVERTEBRATE NEUROSCIENCE 2020; 20:12. [PMID: 32803437 DOI: 10.1007/s10158-020-00247-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/01/2020] [Accepted: 08/06/2020] [Indexed: 02/07/2023]
Abstract
Brugia malayi is a human filarial nematode parasite that causes lymphatic filariasis or 'elephantiasis' a disfiguring neglected tropical disease. This parasite is a more tractable nematode parasite for the experimental study of anthelmintic drugs and has been studied with patch-clamp and RNAi techniques. Unlike in C. elegans however, calcium signaling in B. malayi or other nematode parasites has not been achieved, limiting the studies of the mode of action of anthelmintic drugs. We describe here the development of calcium imaging methods that allow us to characterize changes in cellular calcium in the muscles of B. malayi. This is a powerful technique that can help in elucidating the mode of action of selected anthelmintics. We developed two approaches that allow the recording of calcium signals in the muscles of adult B. malayi: (a) soaking the muscles with Fluo-3AM, promoting large-scale imaging of multiple cells simultaneously and, (b) direct insertion of Fluo-3 using microinjection, providing the possibility of performing dual calcium and electrophysiological recordings. Here, we describe the techniques used to optimize dye entry into the muscle cells and demonstrate that detectable increases in Fluo-3 fluorescence to elevated calcium concentrations can be achieved in B. malayi using both techniques.
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Affiliation(s)
- Paul D E Williams
- Department of Biomedical Sciences, College of Veterinary Medicine, Iowa State University, 1800 Christensen Dr, Ames, IA, 50011, USA
| | - Saurabh Verma
- Department of Biomedical Sciences, College of Veterinary Medicine, Iowa State University, 1800 Christensen Dr, Ames, IA, 50011, USA
| | - Alan P Robertson
- Department of Biomedical Sciences, College of Veterinary Medicine, Iowa State University, 1800 Christensen Dr, Ames, IA, 50011, USA
| | - Richard J Martin
- Department of Biomedical Sciences, College of Veterinary Medicine, Iowa State University, 1800 Christensen Dr, Ames, IA, 50011, USA.
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4
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Saleeba C, Dempsey B, Le S, Goodchild A, McMullan S. Corrigendum: A Student's Guide to Neural Circuit Tracing. Front Neurosci 2020; 14:177. [PMID: 32210751 PMCID: PMC7076267 DOI: 10.3389/fnins.2020.00177] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2020] [Accepted: 02/17/2020] [Indexed: 11/13/2022] Open
Affiliation(s)
- Christine Saleeba
- Neurobiology of Vital Systems Node, Faculty of Medicine and Health Sciences, Macquarie University, Sydney, NSW, Australia
- The School of Physiology, Pharmacology and Neuroscience, University of Bristol, Bristol, United Kingdom
| | - Bowen Dempsey
- CNRS, Hindbrain Integrative Neurobiology Laboratory, Neuroscience Paris-Saclay Institute (Neuro-PSI), Université Paris-Saclay, Gif-sur-Yvette, France
| | - Sheng Le
- Neurobiology of Vital Systems Node, Faculty of Medicine and Health Sciences, Macquarie University, Sydney, NSW, Australia
| | - Ann Goodchild
- Neurobiology of Vital Systems Node, Faculty of Medicine and Health Sciences, Macquarie University, Sydney, NSW, Australia
| | - Simon McMullan
- Neurobiology of Vital Systems Node, Faculty of Medicine and Health Sciences, Macquarie University, Sydney, NSW, Australia
- *Correspondence: Simon McMullan
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5
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Abstract
The zebrafish (Danio rerio) has emerged as a widely used model system during the last four decades. The fact that the zebrafish larva is transparent enables sophisticated in vivo imaging, including calcium imaging of intracellular transients in many different tissues. While being a vertebrate, the reduced complexity of its nervous system and small size make it possible to follow large-scale activity in the whole brain. Its genome is sequenced and many genetic and molecular tools have been developed that simplify the study of gene function in health and disease. Since the mid 90's, the development and neuronal function of the embryonic, larval, and later, adult zebrafish have been studied using calcium imaging methods. This updated chapter is reviewing the advances in methods and research findings of zebrafish calcium imaging during the last decade. The choice of calcium indicator depends on the desired number of cells to study and cell accessibility. Synthetic calcium indicators, conjugated to dextrans and acetoxymethyl (AM) esters, are still used to label specific neuronal cell types in the hindbrain and the olfactory system. However, genetically encoded calcium indicators, such as aequorin and the GCaMP family of indicators, expressed in various tissues by the use of cell-specific promoters, are now the choice for most applications, including brain-wide imaging. Calcium imaging in the zebrafish has contributed greatly to our understanding of basic biological principles during development and adulthood, and the function of disease-related genes in a vertebrate system.
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Saleeba C, Dempsey B, Le S, Goodchild A, McMullan S. A Student's Guide to Neural Circuit Tracing. Front Neurosci 2019; 13:897. [PMID: 31507369 PMCID: PMC6718611 DOI: 10.3389/fnins.2019.00897] [Citation(s) in RCA: 83] [Impact Index Per Article: 16.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2019] [Accepted: 08/12/2019] [Indexed: 12/17/2022] Open
Abstract
The mammalian nervous system is comprised of a seemingly infinitely complex network of specialized synaptic connections that coordinate the flow of information through it. The field of connectomics seeks to map the structure that underlies brain function at resolutions that range from the ultrastructural, which examines the organization of individual synapses that impinge upon a neuron, to the macroscopic, which examines gross connectivity between large brain regions. At the mesoscopic level, distant and local connections between neuronal populations are identified, providing insights into circuit-level architecture. Although neural tract tracing techniques have been available to experimental neuroscientists for many decades, considerable methodological advances have been made in the last 20 years due to synergies between the fields of molecular biology, virology, microscopy, computer science and genetics. As a consequence, investigators now enjoy an unprecedented toolbox of reagents that can be directed against selected subpopulations of neurons to identify their efferent and afferent connectomes. Unfortunately, the intersectional nature of this progress presents newcomers to the field with a daunting array of technologies that have emerged from disciplines they may not be familiar with. This review outlines the current state of mesoscale connectomic approaches, from data collection to analysis, written for the novice to this field. A brief history of neuroanatomy is followed by an assessment of the techniques used by contemporary neuroscientists to resolve mesoscale organization, such as conventional and viral tracers, and methods of selecting for sub-populations of neurons. We consider some weaknesses and bottlenecks of the most widely used approaches for the analysis and dissemination of tracing data and explore the trajectories that rapidly developing neuroanatomy technologies are likely to take.
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Affiliation(s)
- Christine Saleeba
- Neurobiology of Vital Systems Node, Faculty of Medicine and Health Sciences, Macquarie University, Sydney, NSW, Australia
- The School of Physiology, Pharmacology and Neuroscience, University of Bristol, Bristol, United Kingdom
| | - Bowen Dempsey
- CNRS, Hindbrain Integrative Neurobiology Laboratory, Neuroscience Paris-Saclay Institute (Neuro-PSI), Université Paris-Saclay, Gif-sur-Yvette, France
| | - Sheng Le
- Neurobiology of Vital Systems Node, Faculty of Medicine and Health Sciences, Macquarie University, Sydney, NSW, Australia
| | - Ann Goodchild
- Neurobiology of Vital Systems Node, Faculty of Medicine and Health Sciences, Macquarie University, Sydney, NSW, Australia
| | - Simon McMullan
- Neurobiology of Vital Systems Node, Faculty of Medicine and Health Sciences, Macquarie University, Sydney, NSW, Australia
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7
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Discrimination of the hierarchical structure of cortical layers in 2-photon microscopy data by combined unsupervised and supervised machine learning. Sci Rep 2019; 9:7424. [PMID: 31092841 PMCID: PMC6520410 DOI: 10.1038/s41598-019-43432-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2018] [Accepted: 04/18/2019] [Indexed: 12/22/2022] Open
Abstract
The laminar organization of the cerebral cortex is a fundamental characteristic of the brain, with essential implications for cortical function. Due to the rapidly growing amount of high-resolution brain imaging data, a great demand arises for automated and flexible methods for discriminating the laminar texture of the cortex. Here, we propose a combined approach of unsupervised and supervised machine learning to discriminate the hierarchical cortical laminar organization in high-resolution 2-photon microscopic neural image data of mouse brain without observer bias, that is, without the prerequisite of manually labeled training data. For local cortical foci, we modify an unsupervised clustering approach to identify and represent the laminar cortical structure. Subsequently, supervised machine learning is applied to transfer the resulting layer labels across different locations and image data, to ensure the existence of a consistent layer label system. By using neurobiologically meaningful features, the discrimination results are shown to be consistent with the layer classification of the classical Brodmann scheme, and provide additional insight into the structure of the cerebral cortex and its hierarchical organization. Thus, our work paves a new way for studying the anatomical organization of the cerebral cortex, and potentially its functional organization.
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Chamanzar M, Scopelliti MG, Bloch J, Do N, Huh M, Seo D, Iafrati J, Sohal VS, Alam MR, Maharbiz MM. Ultrasonic sculpting of virtual optical waveguides in tissue. Nat Commun 2019; 10:92. [PMID: 30626873 PMCID: PMC6327026 DOI: 10.1038/s41467-018-07856-w] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2016] [Accepted: 11/21/2018] [Indexed: 12/19/2022] Open
Abstract
Optical imaging and stimulation are widely used to study biological events. However, scattering processes limit the depth to which externally focused light can penetrate tissue. Optical fibers and waveguides are commonly inserted into tissue when delivering light deeper than a few millimeters. This approach, however, introduces complications arising from tissue damage. In addition, it makes it difficult to steer light. Here, we demonstrate that ultrasound can be used to define and steer the trajectory of light within scattering media by exploiting local pressure differences created by acoustic waves that result in refractive index contrasts. We show that virtual light pipes can be created deep into the tissue (>18 scattering mean free paths). We demonstrate the application of this technology in confining light through mouse brain tissue. This technology is likely extendable to form arbitrary light patterns within tissue, extending both the reach and the flexibility of light-based methods.
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Affiliation(s)
- Maysamreza Chamanzar
- Electrical and Computer Engineering Department, Carnegie Mellon University, Pittsburgh, 15213, PA, USA.
- Electrical Engineering and Computer Science Department, University of California, Berkeley, 94720, CA, USA.
| | | | - Julien Bloch
- Mechanical Engineering Department, University of California, 94720, Berkeley, CA, USA
| | - Ninh Do
- Mechanical Engineering Department, University of California, 94720, Berkeley, CA, USA
| | - Minyoung Huh
- Electrical Engineering and Computer Science Department, University of California, Berkeley, 94720, CA, USA
| | - Dongjin Seo
- Electrical Engineering and Computer Science Department, University of California, Berkeley, 94720, CA, USA
| | - Jillian Iafrati
- Department of Psychiatry, University of California, San Francisco, 94103, CA, USA
- Center for Integrative Neuroscience, University of California, San Francisco, 94158, CA, USA
| | - Vikaas S Sohal
- Department of Psychiatry, University of California, San Francisco, 94103, CA, USA
- Center for Integrative Neuroscience, University of California, San Francisco, 94158, CA, USA
| | - Mohammad-Reza Alam
- Mechanical Engineering Department, University of California, 94720, Berkeley, CA, USA
| | - Michel M Maharbiz
- Electrical Engineering and Computer Science Department, University of California, Berkeley, 94720, CA, USA
- Bioengineering Department, University of California, Berkeley, 94720, CA, USA
- Center for Neural Engineering and Prostheses, University of California, Berkeley, 94720, CA, USA
- Chan Zuckerberg Biohub, San Francisco, 94158, CA, USA
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9
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Shaping the Output of Lumbar Flexor Motoneurons by Sacral Neuronal Networks. J Neurosci 2016; 37:1294-1311. [PMID: 28025254 DOI: 10.1523/jneurosci.2213-16.2016] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2016] [Revised: 12/11/2016] [Accepted: 12/14/2016] [Indexed: 12/27/2022] Open
Abstract
The ability to improve motor function in spinal cord injury patients by reactivating spinal central pattern generators (CPGs) requires the elucidation of neurons and pathways involved in activation and modulation of spinal networks in accessible experimental models. Previously we reported on adrenoceptor-dependent sacral control of lumbar flexor motoneuron firing in newborn rats. The current work focuses on clarification of the circuitry and connectivity involved in this unique modulation and its potential use. Using surgical manipulations of the spinal gray and white matter, electrophysiological recordings, and confocal microscopy mapping, we found that methoxamine (METH) activation of sacral networks within the ventral aspect of S2 segments was sufficient to produce alternating rhythmic bursting (0.15-1 Hz) in lumbar flexor motoneurons. This lumbar rhythm depended on continuity of the ventral funiculus (VF) along the S2-L2 segments. Interrupting the VF abolished the rhythm and replaced it by slow unstable bursting. Calcium imaging of S1-S2 neurons, back-labeled via the VF, revealed that ∼40% responded to METH, mostly by rhythmic firing. All uncrossed projecting METH responders and ∼70% of crossed projecting METH responders fired with the concurrent ipsilateral motor output, while the rest (∼30%) fired with the contralateral motor output. We suggest that METH-activated sacral CPGs excite ventral clusters of sacral VF neurons to deliver the ascending drive required for direct rhythmic activation of lumbar flexor motoneurons. The capacity of noradrenergic-activated sacral CPGs to modulate the activity of lumbar networks via sacral VF neurons provides a novel way to recruit rostral lumbar motoneurons and modulate the output required to execute various motor behaviors. SIGNIFICANCE STATEMENT Spinal central pattern generators (CPGs) produce the rhythmic output required for coordinating stepping and stabilizing the body axis during movements. Electrical stimulation and exogenous drugs can reactivate the spinal CPGs and improve the motor function in the absence of descending supraspinal control. Since the body-stabilizing sacral networks can activate and modulate the limb-moving lumbar circuitry, it is important to clarify the functional organization of sacral and lumbar networks and their linking pathways. Here we decipher the ascending circuitry linking adrenoceptor-activated sacral CPGs and lumbar flexor motoneurons, thereby providing novel insights into mechanisms by which sacral circuitry recruits lumbar flexors, and enhances the motor output during lumbar afferent-induced locomotor rhythms. Moreover, our findings might help to improve drug/electrical stimulation-based therapy to accelerate locomotor-based rehabilitation.
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10
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Mandadi S, Leduc-Pessah H, Hong P, Ejdrygiewicz J, Sharples SA, Trang T, Whelan PJ. Modulatory and plastic effects of kinins on spinal cord networks. J Physiol 2016; 594:1017-36. [PMID: 26634895 DOI: 10.1113/jp271152] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2015] [Accepted: 11/24/2015] [Indexed: 12/22/2022] Open
Abstract
KEY POINTS Inflammatory kinins are released following spinal cord injury or neurotrauma. The effects of these kinins on ongoing locomotor activity of central pattern generator networks are unknown. In the present study, kinins were shown to have short- and long-term effects on motor networks. The short-term effects included direct depolarization of interneurons and motoneurons in the ventral horn accompanied by modulation of transient receptor potential vanilloid 1-sensitive nociceptors in the dorsal horn. Over the long-term, we observed a bradykinin-mediated effect on promoting plasticity in the spinal cord. In a model of spinal cord injury, we observed an increase in microglia numbers in both the dorsal and ventral horn and, in a microglia cell culture model, we observed bradykinin-induced expression of glial-derived neurotrophic factor. ABSTRACT The expression and function of inflammatory mediators in the developing spinal cord remain poorly characterized. We discovered novel, short and long-term roles for the inflammatory nonapeptide bradykinin (BK) and its receptor bradykinin receptor B2 (B2R) in the neuromodulation of developing sensorimotor networks following a spinal cord injury (SCI), suggesting that BK participates in an excitotoxic cascade. Functional expression of B2R was confirmed by a transient disruptive action of BK on fictive locomotion generated by a combination of NMDA, 5-HT and dopamine. The role of BK in the dorsal horn nociceptive afferents was tested using spinal cord attached to one-hind-limb (HL) preparations. In the HL preparations, BK at a subthreshold concentration induced transient disruption of fictive locomotion only in the presence of: (1) noxious heat applied to the hind paw and (2) the heat sensing ion channel transient receptor potential vanilloid 1 (TRPV1), known to be restricted to nociceptors in the superficial dorsal horn. BK directly depolarized motoneurons and ascending interneurons in the ventrolateral funiculus. We found a key mechanism for BK in promoting long-term plasticity within the spinal cord. Using a model of neonatal SCI and a microglial cell culture model, we examined the role of BK in inducing activation of microglia and expression of glial-derived neurotrophic factor (GDNF). In the neonatal SCI model, we observed an increase in microglia numbers and increased GDNF expression restricted to microglia. In the microglia cell culture model, we observed a BK-induced increased expression of GDNF via B2R, suggesting a novel mechanism for BK spinal-mediated plasticity.
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Affiliation(s)
- S Mandadi
- Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada.,Department of Physiology and Pharmacology, University of Calgary, Calgary, Alberta, Canada
| | - H Leduc-Pessah
- Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada.,Department of Physiology and Pharmacology, University of Calgary, Calgary, Alberta, Canada.,Department of Comparative Biology and Experimental Medicine, University of Calgary, Calgary, Alberta, Canada
| | - P Hong
- Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada
| | - J Ejdrygiewicz
- Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada.,Department of Comparative Biology and Experimental Medicine, University of Calgary, Calgary, Alberta, Canada
| | - S A Sharples
- Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada.,Department of Comparative Biology and Experimental Medicine, University of Calgary, Calgary, Alberta, Canada
| | - T Trang
- Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada.,Department of Physiology and Pharmacology, University of Calgary, Calgary, Alberta, Canada.,Department of Comparative Biology and Experimental Medicine, University of Calgary, Calgary, Alberta, Canada
| | - P J Whelan
- Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada.,Department of Physiology and Pharmacology, University of Calgary, Calgary, Alberta, Canada.,Department of Comparative Biology and Experimental Medicine, University of Calgary, Calgary, Alberta, Canada
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11
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Abstract
Genetically encoded optical actuators and indicators have changed the landscape of neuroscience, enabling targetable control and readout of specific components of intact neural circuits in behaving animals. Here, we review the development of optical neural interfaces, focusing on hardware designed for optical control of neural activity, integrated optical control and electrical readout, and optical readout of population and single-cell neural activity in freely moving mammals.
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Affiliation(s)
- Melissa R Warden
- Department of Neurobiology and Behavior, Cornell University, Ithaca, New York 14853;
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12
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Nasse JS. A novel slice preparation to study medullary oromotor and autonomic circuits in vitro. J Neurosci Methods 2014; 237:41-53. [PMID: 25196216 DOI: 10.1016/j.jneumeth.2014.08.023] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2014] [Revised: 08/22/2014] [Accepted: 08/24/2014] [Indexed: 11/28/2022]
Abstract
BACKGROUND The medulla is capable of controlling and modulating ingestive behavior and gastrointestinal function. These two functions, which are critical to maintaining homeostasis, are governed by an interconnected group of nuclei dispersed throughout the medulla. As such, in vitro experiments to study the neurophysiologic details of these connections have been limited by spatial constraints of conventional slice preparations. NEW METHOD This study demonstrates a novel method of sectioning the medulla so that sensory, integrative, and motor nuclei that innervate the gastrointestinal tract and the oral cavity remain intact. RESULTS Immunohistochemical staining against choline-acetyl-transferase and dopamine-β-hydroxylase demonstrated that within a 450 μm block of tissue we are able to capture sensory, integrative and motor nuclei that are critical to oromotor and gastrointestinal function. Within slice tracing shows that axonal projections from the NST to the reticular formation and from the reticular formation to the hypoglossal motor nucleus (mXII) persist. Live-cell calcium imaging of the slice demonstrates that stimulation of either the rostral or caudal NST activates neurons throughout the NST, as well as the reticular formation and mXII. COMPARISON WITH EXISTING METHODS This new method of sectioning captures a majority of the nuclei that are active when ingesting a meal. Tradition planes of section, i.e. coronal, horizontal or sagittal, contain only a limited portion of the substrate. CONCLUSIONS Our results demonstrate that both anatomical and physiologic connections of oral and visceral sensory nuclei that project to integrative and motor nuclei remain intact with this new plane of section.
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Affiliation(s)
- Jason S Nasse
- Division of Biosciences, College of Dentistry, 305 West 12th Avenue, 4154 Postle Hall, The Ohio State University, Columbus, OH 43210, United States.
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13
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Finkel E, Etlin A, Cherniak M, Mor Y, Lev-Tov A, Anglister L. Neuroanatomical basis for cholinergic modulation of locomotor networks by sacral relay neurons with ascending lumbar projections. J Comp Neurol 2014; 522:3437-55. [DOI: 10.1002/cne.23613] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2013] [Revised: 04/10/2014] [Accepted: 04/14/2014] [Indexed: 12/28/2022]
Affiliation(s)
- Eran Finkel
- Department of Medical Neurobiology, IMRIC; Hebrew University-Hadassah Medical School; Jerusalem 91120 Israel
| | - Alex Etlin
- Department of Medical Neurobiology, IMRIC; Hebrew University-Hadassah Medical School; Jerusalem 91120 Israel
| | - Meir Cherniak
- Department of Medical Neurobiology, IMRIC; Hebrew University-Hadassah Medical School; Jerusalem 91120 Israel
| | - Yoav Mor
- Department of Medical Neurobiology, IMRIC; Hebrew University-Hadassah Medical School; Jerusalem 91120 Israel
| | - Aharon Lev-Tov
- Department of Medical Neurobiology, IMRIC; Hebrew University-Hadassah Medical School; Jerusalem 91120 Israel
| | - Lili Anglister
- Department of Medical Neurobiology, IMRIC; Hebrew University-Hadassah Medical School; Jerusalem 91120 Israel
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14
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In vivo imaging of immediate early gene expression reveals layer-specific memory traces in the mammalian brain. Proc Natl Acad Sci U S A 2014; 111:2788-93. [PMID: 24550309 DOI: 10.1073/pnas.1316808111] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
The dynamic processes of formatting long-term memory traces in the cortex are poorly understood. The investigation of these processes requires measurements of task-evoked neuronal activities from large numbers of neurons over many days. Here, we present a two-photon imaging-based system to track event-related neuronal activity in thousands of neurons through the quantitative measurement of EGFP proteins expressed under the control of the EGR1 gene promoter. A recognition algorithm was developed to detect GFP-positive neurons in multiple cortical volumes and thereby to allow the reproducible tracking of 4,000 neurons in each volume for 2 mo. The analysis revealed a context-specific response in sparse layer II neurons. The context-evoked response gradually increased during several days of training and was maintained 1 mo later. The formed traces were specifically activated by the training context and were linearly correlated with the behavioral response. Neuronal assemblies that responded to specific contexts were largely separated, indicating the sparse coding of memory-related traces in the layer II cortical circuit.
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15
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Mandadi S, Hong P, Tran MA, Bráz JM, Colarusso P, Basbaum AI, Whelan PJ. Identification of multisegmental nociceptive afferents that modulate locomotor circuits in the neonatal mouse spinal cord. J Comp Neurol 2014; 521:2870-87. [PMID: 23436436 DOI: 10.1002/cne.23321] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2012] [Revised: 02/08/2013] [Accepted: 02/11/2013] [Indexed: 11/06/2022]
Abstract
Compared to proprioceptive afferent collateral projections, less is known about the anatomical, neurochemical, and functional basis of nociceptive collateral projections modulating lumbar central pattern generators (CPG). Quick response times are critical to ensure rapid escape from aversive stimuli. Furthermore, sensitization of nociceptive afferent pathways can contribute to a pathological activation of motor circuits. We investigated the extent and role of collaterals of capsaicin-sensitive nociceptive sacrocaudal afferent (nSCA) nerves that directly ascend several spinal segments in Lissauer's tract and the dorsal column and regulate motor activity. Anterograde tracing demonstrated direct multisegmental projections of the sacral dorsal root 4 (S4) afferent collaterals in Lissauer's tract and in the dorsal column. Subsets of the traced S4 afferent collaterals expressed transient receptor potential vanilloid 1 (TRPV1), which transduces a nociceptive response to capsaicin. Electrophysiological data revealed that S4 dorsal root stimulation could evoke regular rhythmic bursting activity, and our data suggested that capsaicin-sensitive collaterals contribute to CPG activation across multiple segments. Capsaicin's effect on S4-evoked locomotor activity was potent until the lumbar 5 (L5) segments, and diminished in rostral segments. Using calcium imaging we found elevated calcium transients within Lissauer's tract and dorsal column at L5 segments when compared to the calcium transients only within the dorsal column at the lumbar 2 (L2) segments, which were desensitized by capsaicin. We conclude that lumbar locomotor networks in the neonatal mouse spinal cord are targets for modulation by direct multisegmental nSCA, subsets of which express TRPV1 in Lissauer's tract and the dorsal column. J. Comp. Neurol. 521:2870-2887, 2013. © 2013 Wiley Periodicals, Inc.
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Affiliation(s)
- Sravan Mandadi
- Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, T2N 4N1, Canada; Department of Physiology and Pharmacology, University of Calgary, Calgary, Alberta, T2N 4N1, Canada
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Perreault MC, Glover JC. Glutamatergic reticulospinal neurons in the mouse: developmental origins, axon projections, and functional connectivity. Ann N Y Acad Sci 2013; 1279:80-9. [PMID: 23531005 DOI: 10.1111/nyas.12054] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Subcortical descending glutamatergic neurons, such as reticulospinal (RS) neurons, play decisive roles in the initiation and control of many motor behaviors in mammals. However, little is known about the mechanisms used by RS neurons to control spinal motor networks because most of the neuronal elements involved have not been identified and characterized. In this review, we compare, in the embryonic mouse, the timing of developmental events that lead to the formation of synaptic connections between RS and spinal cord neurons. We then summarize our recent research in the postnatal mouse on the organization of synaptic connections between RS neurons and lumbar axial motoneurons (MNs), hindlimb MNs, and commissural interneurons. Finally, we give a brief account of some of the most recent studies on the intrinsic capabilities for plasticity of the mammalian RS system. The present review should give an updated insight into how functional specificity in RS motor networks emerges.
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Characterization of sacral interneurons that mediate activation of locomotor pattern generators by sacrocaudal afferent input. J Neurosci 2013; 33:734-47. [PMID: 23303951 DOI: 10.1523/jneurosci.4390-12.2013] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Identification of the neural pathways involved in retraining the spinal central pattern generators (CPGs) by afferent input in the absence of descending supraspinal control is feasible in isolated rodent spinal cords where the locomotor CPGs are potently activated by sacrocaudal afferent (SCA) input. Here we study the involvement of sacral neurons projecting rostrally through the ventral funiculi (VF) in activation of the CPGs by sensory stimulation. Fluorescent labeling and immunostaining showed that VF neurons are innervated by primary afferents immunoreactive for vesicular glutamate transporters 1 and 2 and by intraspinal neurons. Calcium imaging revealed that 55% of the VF neurons were activated by SCA stimulation. The activity of VF neurons and the sacral and lumbar CPGs was abolished when non-NMDA receptors in the sacral segments were blocked by the antagonist CNQX. When sacral NMDA receptors were blocked by APV, the sacral CPGs were suppressed, VF neurons with nonrhythmic activity were recruited and a moderate-drive locomotor rhythm developed during SCA stimulation. In contrast, when the sacral CPGs were activated by SCA stimulation, rhythmic and nonrhythmic VF neurons were recruited and the locomotor rhythm was most powerful. The activity of 73 and 27% of the rhythmic VF neurons was in-phase with the ipsilateral and contralateral motor output, respectively. Collectively, our studies indicate that sacral VF neurons serve as a major link between SCA and the hindlimb CPGs and that the ability of SCA to induce stepping can be enhanced by the sacral CPGs. The nature of the ascending drive to lumbar CPGs, the identity of subpopulations of VF neurons, and their potential role in activating the locomotor rhythm are discussed.
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Blivis D, O'Donovan MJ. Retrograde loading of nerves, tracts, and spinal roots with fluorescent dyes. J Vis Exp 2012:4008. [PMID: 22547001 DOI: 10.3791/4008] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
Retrograde labeling of neurons is a standard anatomical method(1,2) that has also been used to load calcium and voltage-sensitive dyes into neurons(3-6). Generally, the dyes are applied as solid crystals or by local pressure injection using glass pipettes. However, this can result in dilution of the dye and reduced labeling intensity, particularly when several hours are required for dye diffusion. Here we demonstrate a simple and low-cost technique for introducing fluorescent and ion-sensitive dyes into neurons using a polyethylene suction pipette filled with the dye solution. This method offers a reliable way for maintaining a high concentration of the dye in contact with axons throughout the loading procedure.
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Affiliation(s)
- Dvir Blivis
- Developmental Neurobiology Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, USA.
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Brenowitz SD, Regehr WG. Presynaptic imaging of projection fibers by in vivo injection of dextran-conjugated calcium indicators. Cold Spring Harb Protoc 2012; 2012:465-71. [PMID: 22474660 DOI: 10.1101/pdb.prot068551] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Dextran-conjugated calcium indicators are stably retained within neurons. As a result, they are well suited to measuring presynaptic calcium at physiological temperatures. In addition, dextran indicators can be used to label neurons and their presynaptic boutons in vivo. This has allowed measurements of calcium in the presynaptic boutons of projection fibers that cannot be stably loaded with other types of indicators. This protocol describes a technique for in vivo loading of the climbing fiber projection to the cerebellum with dextran-conjugated indicators for subsequent presynaptic calcium imaging in brain slices. This technique is applicable to studies of projection fibers in many species from which brain slices can be prepared. The dextran indicator is injected into the inferior olive using a stereotaxic device. After a period of 1-3 d, cerebellar slices are prepared and presynaptic calcium transients are measured at physiological temperature in labeled climbing fibers. The protocol also discusses important considerations for using dextran-conjugated indicators to measure presynaptic calcium.
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Russell JT. Imaging calcium signals in vivo: a powerful tool in physiology and pharmacology. Br J Pharmacol 2012; 163:1605-25. [PMID: 20718728 DOI: 10.1111/j.1476-5381.2010.00988.x] [Citation(s) in RCA: 88] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
The design and engineering of organic fluorescent Ca(2+) indicators approximately 30 years ago opened the door for imaging cellular Ca(2+) signals with a high degree of temporal and spatial resolution. Over this time, Ca(2+) imaging has revolutionized our approaches for tissue-level spatiotemporal analysis of functional organization and has matured into a powerful tool for in situ imaging of cellular activity in the living animal. In vivo Ca(2+) imaging with temporal resolution at the millisecond range and spatial resolution at micrometer range has been achieved through novel designs of Ca(2+) sensors, development of modern microscopes and powerful imaging techniques such as two-photon microscopy. Imaging Ca(2+) signals in ensembles of cells within tissue in 3D allows for analysis of integrated cellular function, which, in the case of the brain, enables recording activity patterns in local circuits. The recent development of miniaturized compact, fibre-optic-based, mechanically flexible microendoscopes capable of two-photon microscopy opens the door for imaging activity in awake, behaving animals. This development is poised to open a new chapter in physiological experiments and for pharmacological approaches in the development of novel therapies.
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Affiliation(s)
- James T Russell
- Section on Cell Biology and Signal Transduction, Laboratory of Cellular and Molecular Neurophysiology, National Institute of Child Health and Human Development/NIH, 49 Convent Drive, Bethesda, MD 20892-4480, USA.
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Kettunen P. Calcium imaging in the zebrafish. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2012; 740:1039-71. [PMID: 22453983 DOI: 10.1007/978-94-007-2888-2_48] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
The zebrafish (Danio rerio) has emerged as a new model system during the last three decades. The fact that the zebrafish larva is transparent enables sophisticated in vivo imaging. While being the vertebrate, the reduced complexity of its nervous system and small size make it possible to follow large-scale activity in the whole brain. Its genome is sequenced and many genetic and molecular tools have been developed that simplify the study of gene function. Since the mid 1990s, the embryonic development and neuronal function of the larval, and later, adult zebrafish have been studied using calcium imaging methods. The choice of calcium indicator depends on the desired number of cells to study and cell accessibility. Dextran indicators have been used to label cells in the developing embryo from dye injection into the one-cell stage. Dextrans have also been useful for retrograde labeling of spinal cord neurons and cells in the olfactory system. Acetoxymethyl (AM) esters permit labeling of larger areas of tissue such as the tectum, a region responsible for visual processing. Genetically encoded calcium indicators have been expressed in various tissues by the use of cell-specific promoters. These studies have contributed greatly to our understanding of basic biological principles during development and adulthood, and of the function of disease-related genes in a vertebrate system.
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Affiliation(s)
- Petronella Kettunen
- Institute of Neuroscience and Physiology, Sahlgrenska Academy at the University of Gothenburg, Sweden.
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Whelan PJ. Shining light into the black box of spinal locomotor networks. Philos Trans R Soc Lond B Biol Sci 2010; 365:2383-95. [PMID: 20603359 DOI: 10.1098/rstb.2009.0322] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Rhythmic activity is responsible for numerous essential motor functions including locomotion, breathing and chewing. In the case of locomotion, it has been realized for some time that the spinal cord contains sufficient circuitry to produce a sophisticated stepping pattern. However, the central pattern generator for locomotion in mammals has remained a 'black box' where inputs to the network were manipulated and the outputs interpreted. Over the last decade, new genetic approaches and techniques have been developed that provide ways to identify and manipulate the activity of classes of interneurons. The use of these techniques will be critically discussed and related to current models of network function.
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Affiliation(s)
- Patrick J Whelan
- Department of Comparative Biology and Experimental Medicine, Hotchkiss Brain Institute, HS 2119, University of Calgary, Calgary, Alberta, Canada.
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Kasumacic N, Glover JC, Perreault MC. Segmental patterns of vestibular-mediated synaptic inputs to axial and limb motoneurons in the neonatal mouse assessed by optical recording. J Physiol 2010; 588:4905-25. [PMID: 20962007 DOI: 10.1113/jphysiol.2010.195644] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Proper control of movement and posture occurs partly via descending projections from the vestibular nuclei to spinal motor circuits. Days before birth in rodents, vestibulospinal neurons develop axonal projections that extend to the spinal cord. How functional these projections are just after birth is unknown. Our goal was to assess the overall functional organization of vestibulospinal inputs to spinal motoneurons in a brainstem-spinal cord preparation of the neonatal mouse (postnatal day (P) 0-5). Using calcium imaging, we recorded responses evoked by electrical stimulation of the VIIIth nerve, in many motoneurons simultaneously throughout the spinal cord (C2, C6, T7, L2 and L5 segments), in the medial and lateral motor columns. Selective lesions in the brainstem and/or spinal cord distinguished which tracts contributed to the responses: those in the cervical cord originated primarily from the medial vestibulospinal tracts but with a substantial contribution from the lateral vestibulospinal tract; those in the thoracolumbar cord originated exclusively from the lateral vestibulospinal tract. In the thoracolumbar but not the cervical cord, excitatory commissural connections mediated vestibular responses in contralateral motoneurons. Pharmacological blockade of GABA(A) receptors showed that responses involved a convergence of excitatory and inhibitory inputs which in combination produced temporal response patterns specific for different segmental levels. Our results show that by birth vestibulospinal projections in rodents have already established functional synapses and are organized to differentially regulate activity in neck and limb motoneurons in a tract- and segment-specific pattern similar to that in adult mammals. Thus, this particular set of descending projections develops several key features of connectivity appropriately at prenatal stages. We also present novel information about vestibulospinal inputs to axial motoneurons in mammals, providing a more comprehensive platform for future studies into the overall organization of vestibulospinal inputs and their role in regulating postural stability.
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Affiliation(s)
- Nedim Kasumacic
- Department of Physiology, University of Oslo, Institute of Basic Medical Sciences, Sognsvannsveien 9, PB 1103 Blindern, N-0317 Oslo, Norway
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Dorostkar MM, Dreosti E, Odermatt B, Lagnado L. Computational processing of optical measurements of neuronal and synaptic activity in networks. J Neurosci Methods 2010; 188:141-50. [PMID: 20152860 PMCID: PMC2849931 DOI: 10.1016/j.jneumeth.2010.01.033] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2009] [Revised: 01/27/2010] [Accepted: 01/28/2010] [Indexed: 12/20/2022]
Abstract
Imaging of optical reporters of neural activity across large populations of neurones is a widely used approach for investigating the function of neural circuits in slices and in vivo. Major challenges in analysing such experiments include the automatic identification of neurones and synapses, extraction of dynamic signals, and assessing the temporal and spatial relationships between active units in relation to the gross structure of the circuit. We have developed an integrated set of software tools, named SARFIA, by which these aspects of dynamic imaging experiments can be analysed semi-automatically. Key features are image-based detection of structures of interest using the Laplace operator, determining the positions of units in a layered network, clustering algorithms to classify units with similar functional responses, and a database to store, exchange and analyse results across experiments. We demonstrate the use of these tools to analyse synaptic activity in the retina of live zebrafish by multi-photon imaging of SyGCaMP2, a genetically encoded synaptically localised calcium reporter. By simultaneously recording activity across tens of bipolar cell terminals distributed throughout the IPL we made a functional map of the ON and OFF signalling channels and found that these were only partially separated. The automated detection of signals across many neurones in the retina allowed the reliable detection of small populations of neurones generating “ectopic” signals in the “ON” and “OFF” sublaminae. This software should be generally applicable for the analysis of dynamic imaging experiments across hundreds of responding units.
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Delaney KR. Loading neurons with dextran-conjugated calcium indicators in intact nervous tissue. CURRENT PROTOCOLS IN NEUROSCIENCE 2010; Chapter 2:Unit2.5. [PMID: 20066656 DOI: 10.1002/0471142301.ns0205s50] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Dextran-conjugated Ca(2+) indicators are retained well in neurons for many days following loading in intact or semi-intact brain tissue. Methods for loading neurons, as well as discussion of the unique properties of dextran-conjugated dyes which need to be considered for their use, are presented.
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Fields DR, Shneider N, Mentis GZ, O'Donovan MJ. Imaging nervous system activity. CURRENT PROTOCOLS IN NEUROSCIENCE 2009; Chapter 2:Unit 2.3. [PMID: 19802815 DOI: 10.1002/0471142301.ns0203s49] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
This unit describes methods for loading ion- and voltage-sensitive dyes into neurons, with a particular focus on the spinal cord as a model system. In addition, we describe the use of these dyes to visualize neural activity. Although the protocols described here concern spinal networks in culture or an intact in vitro preparation, they can be, and have been, widely used in other parts of the nervous system.
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Affiliation(s)
- Douglas R Fields
- Section on Nervous System Development and Plasticity, National Institute of Child Health and Human Development (NICHD), NIH, Bethesda, Maryland, USA
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Mochida H, Fortin G, Champagnat J, Glover JC. Differential Involvement of Projection Neurons During Emergence of Spontaneous Activity in the Developing Avian Hindbrain. J Neurophysiol 2009; 101:591-602. [DOI: 10.1152/jn.90835.2008] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
To better characterize the emergence of spontaneous neuronal activity in the developing hindbrain, spontaneous activity was recorded optically from defined projection neuron populations in isolated preparations of the brain stem of the chicken embryo. Ipsilaterally projecting reticulospinal (RS) neurons and several groups of vestibuloocular (VO) neurons were labeled retrogradely with Calcium Green-1 dextran amine and spontaneous calcium transients were recorded using a charge-coupled-device camera mounted on a fluorescence microscope. Simultaneous extracellular recordings were made from one of the trigeminal motor nerves (nV) to register the occurrence of spontaneous synchronous bursts of activity. Two types of spontaneous activity were observed: synchronous events (SEs), which occurred in register with spontaneous bursts in nV once every few minutes and were tetrodotoxin (TTX) dependent, and asynchronous events (AEs), which occurred in the intervals between SEs and were TTX resistant. AEs occurred developmentally before SEs and were in general smaller and more variable in amplitude than SEs. SEs appeared at the same stage as nV bursts early on embryonic day 4, first in RS neurons and then in VO neurons. All RS neurons participated equally in SEs from the outset, whereas different subpopulations of VO neurons participated differentially, both in terms of the proportion of neurons that exhibited SEs, the fidelity with which the SEs in individual neurons followed the nV bursts, and the developmental stage at which SEs appeared and matured. The results show that spontaneous activity is expressed heterogeneously among hindbrain projection neuron populations, suggesting its differential involvement in the formation of different functional neuronal circuits.
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Wide-field and two-photon imaging of brain activity with voltage- and calcium-sensitive dyes. Methods Mol Biol 2009; 489:43-79. [PMID: 18839087 DOI: 10.1007/978-1-59745-543-5_3] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
This chapter presents three examples of imaging brain activity with voltage- or calcium-sensitive dyes. Because experimental measurements are limited by low sensitivity, the chapter then discusses the methodological aspects that are critical for optimal signal-to-noise ratio. Two of the examples use wide-field (1-photon) imaging and the third uses two-photon scanning microscopy. These methods have relatively high temporal resolution ranging from 10 to 10,000 Hz. The three examples are the following: (1) Internally injected voltage-sensitive dye can be used to monitor membrane potential in the dendrites of invertebrate and vertebrate neurons in in vitro preparations. These experiments are directed at understanding how individual neurons convert the complex input synaptic activity into the output spike train. (2) Recently developed methods for staining many individual cells in the mammalian brain with calcium-sensitive dyes together with two-photon microscopy made it possible to follow the spike activity of many neurons simultaneously while in vivo preparations are responding to stimulation. (3) Calcium-sensitive dyes that are internalized into olfactory receptor neurons in the nose will, after several days, be transported to the nerve terminals of these cells in the olfactory bulb glomeruli. There, the population signals can be used as a measure of the input from the nose to the bulb. Three kinds of noise in measuring light intensity are discussed: (1) Shot noise from the random emission of photons from the preparation. (2) Extraneous (technical) noise from external sources. (3) Noise that occurs in the absence of light, the dark noise. In addition, we briefly discuss the light sources, the optics, and the detectors and cameras. The commonly used organic voltage and ion sensitive dyes stain all of the cell types in the preparation indiscriminately. A major effort is underway to find methods for staining individual cell types in the brain selectively. Most of these efforts center around fluorescent protein activity sensors because transgenic methods can be used to express them in individual cell types.
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O'Donovan MJ, Bonnot A, Mentis GZ, Arai Y, Chub N, Shneider NA, Wenner P. Imaging the spatiotemporal organization of neural activity in the developing spinal cord. Dev Neurobiol 2008; 68:788-803. [PMID: 18383543 DOI: 10.1002/dneu.20620] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
In this review, we discuss the use of imaging to visualize the spatiotemporal organization of network activity in the developing spinal cord of the chick embryo and the neonatal mouse. We describe several different methods for loading ion- and voltage-sensitive dyes into spinal neurons and consider the advantages and limitations of each one. We review work in the chick embryo, suggesting that motoneurons play a critical role in the initiation of each cycle of spontaneous network activity and describe how imaging has been used to identify a class of spinal interneuron that appears to be the avian homolog of mammalian Renshaw cells or 1a-inhibitory interneurons. Imaging of locomotor-like activity in the neonatal mouse revealed a wave-like activation of motoneurons during each cycle of discharge. We discuss the significance of this finding and its implications for understanding how locomotor-like activity is coordinated across different segments of the cord. In the last part of the review, we discuss some of the exciting new prospects for the future.
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Affiliation(s)
- Michael J O'Donovan
- National Institute of Neurological Disorder and Stroke, NIH, Bethesda, Maryland 20892, USA.
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Delaney KR. Loading neurons with dextran-conjugated calcium indicators in intact nervous tissue. ACTA ACUST UNITED AC 2008; Chapter 2:Unit 2.5. [PMID: 18428558 DOI: 10.1002/0471142301.ns0205s20] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
This unit describes methods for filling populations of neurons and their processes, including presynaptic terminals, with dextran-conjugated calcium indicators in central nervous tissue of mammals and lower vertebrates. Techniques for filling neurons in vivo for subsequent analysis either in vivo or in brain slices or en bloc preparations are described. These methods are also suitable for staining neurons in acute and organotypic brain slices.
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Fields RD, O'Donovan MJ. Imaging nervous system activity. CURRENT PROTOCOLS IN NEUROSCIENCE 2008; Chapter 2:Unit 2.3. [PMID: 18428458 DOI: 10.1002/0471142301.ns0203s00] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Optical imaging methods rely upon visualization of three types of signals: (1) intrinsic optical signals, including light scattering and reflectance, birefringence, and spectroscopic changes of intrinsic molecules, such as NADH or oxyhemoglobin; (2) changes in fluorescence or absorbance of voltage-sensitive membrane dyes; and (3) changes in fluorescence or absorbance of calcium-sensitive indicator dyes. Of these, the most widely used approach is fluorescent microscopy of calcium-sensitive dyes. This unit describes protocols for the use of calcium-sensitive dyes and voltage-dependent dyes for studies of neuronal activity in culture, tissue slices, and en-bloc preparations of the central nervous system.
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Affiliation(s)
- R D Fields
- National Institute of Child Health and Human Development, Bethesda, Maryland, USA
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Luo L, Callaway EM, Svoboda K. Genetic dissection of neural circuits. Neuron 2008; 57:634-60. [PMID: 18341986 DOI: 10.1016/j.neuron.2008.01.002] [Citation(s) in RCA: 551] [Impact Index Per Article: 34.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2007] [Revised: 12/24/2007] [Accepted: 01/01/2008] [Indexed: 11/29/2022]
Abstract
Understanding the principles of information processing in neural circuits requires systematic characterization of the participating cell types and their connections, and the ability to measure and perturb their activity. Genetic approaches promise to bring experimental access to complex neural systems, including genetic stalwarts such as the fly and mouse, but also to nongenetic systems such as primates. Together with anatomical and physiological methods, cell-type-specific expression of protein markers and sensors and transducers will be critical to construct circuit diagrams and to measure the activity of genetically defined neurons. Inactivation and activation of genetically defined cell types will establish causal relationships between activity in specific groups of neurons, circuit function, and animal behavior. Genetic analysis thus promises to reveal the logic of the neural circuits in complex brains that guide behaviors. Here we review progress in the genetic analysis of neural circuits and discuss directions for future research and development.
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Affiliation(s)
- Liqun Luo
- Department of Biology, Howard Hughes Medical Institute, Stanford University, Stanford, CA 94305, USA
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Abstract
Spatiotemporal activity patterns in local neural networks are fundamental to brain function. Network activity can now be measured in vivo using two-photon imaging of cell populations that are labeled with fluorescent calcium indicators. In this review, we discuss basic aspects of in vivo calcium imaging and highlight recent developments that will help to uncover operating principles of neural circuits.
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Affiliation(s)
- Werner Göbel
- Department of Neurophysiology, Brain Research Institute, University of Zurich, Zurich, Switzerland
| | - Fritjof Helmchen
- Department of Neurophysiology, Brain Research Institute, University of Zurich, Zurich, Switzerland
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36
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Fetcho JR, Higashijima SI, McLean DL. Zebrafish and motor control over the last decade. ACTA ACUST UNITED AC 2007; 57:86-93. [PMID: 17825423 PMCID: PMC2237884 DOI: 10.1016/j.brainresrev.2007.06.018] [Citation(s) in RCA: 91] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2007] [Accepted: 06/20/2007] [Indexed: 11/23/2022]
Abstract
The combination of transparency and accessible genetics is making zebrafish an increasingly important model in studies of motor control. Much of the work on the model has been done over the past decade. Here we review some of the highlights of this work that serve to reveal both the power of the model and its prospects for providing important future insights into the links between neural networks and behavior.
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Affiliation(s)
- Joseph R Fetcho
- W103 Mudd Hall, Department of Neurobiology and Behavior, Cornell University, Ithaca, NY 14853, USA.
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37
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Nagayama S, Zeng S, Xiong W, Fletcher ML, Masurkar AV, Davis DJ, Pieribone VA, Chen WR. In vivo simultaneous tracing and Ca(2+) imaging of local neuronal circuits. Neuron 2007; 53:789-803. [PMID: 17359915 PMCID: PMC1892750 DOI: 10.1016/j.neuron.2007.02.018] [Citation(s) in RCA: 105] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2006] [Revised: 01/26/2007] [Accepted: 02/20/2007] [Indexed: 11/29/2022]
Abstract
A central question about the brain is how information is processed by large populations of neurons embedded in intricate local networks. Answering this question requires not only monitoring functional dynamics of many neurons simultaneously, but also interpreting such activity patterns in the context of neuronal circuitry. Here, we introduce a versatile approach for loading Ca(2+) indicators in vivo by local electroporation. With this method, Ca(2+) imaging can be performed both at neuron population level and with exquisite subcellular resolution down to dendritic spines and axon boutons. This enabled mitral cell odor-evoked ensemble activity to be analyzed simultaneously with revealing their specific connectivity to different glomeruli. Colabeling of Purkinje cell dendrites and intersecting parallel fibers allowed Ca(2+) imaging of both presynaptic boutons and postsynaptic dendrites. This approach thus provides an unprecedented capability for in vivo visualizing active cell ensembles and tracing their underlying local neuronal circuits.
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Affiliation(s)
- Shin Nagayama
- Deptartment of Neurobiology, Yale University, New Haven, CT 06520-8001
| | - Shaoqun Zeng
- Deptartment of Neurobiology, Yale University, New Haven, CT 06520-8001
- The Key Laboratory of Biomedical Photonics of the Ministry of Education-Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan, 430074, China
| | - Wenhui Xiong
- Deptartment of Neurobiology, Yale University, New Haven, CT 06520-8001
| | - Max L. Fletcher
- Deptartment of Neurobiology, Yale University, New Haven, CT 06520-8001
| | - Arjun V. Masurkar
- Deptartment of Neurobiology, Yale University, New Haven, CT 06520-8001
| | - Douglas J. Davis
- The John B. Pierce Laboratory, New Haven, CT 06519
- Department of Molecular and Cellular Physiology, Yale University, New Haven, CT 06510
| | - Vincent A. Pieribone
- The John B. Pierce Laboratory, New Haven, CT 06519
- Department of Molecular and Cellular Physiology, Yale University, New Haven, CT 06510
| | - Wei R. Chen
- Deptartment of Neurobiology, Yale University, New Haven, CT 06520-8001
- Corresponding Author: Dr. Wei R. Chen, Yale University, Department of Neurobiology, 333 Cedar Street, SHM C303, New Haven, CT 06520-8001, Tel: (203) 785 5459, Fax: (203) 785 6990, E-Mail:
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Xu H, Clement A, Wright TM, Wenner P. Developmental reorganization of the output of a GABAergic interneuronal circuit. J Neurophysiol 2007; 97:2769-79. [PMID: 17251359 DOI: 10.1152/jn.01324.2006] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Locally projecting inhibitory interneurons play a crucial role in the patterning and timing of network activity. However, because of their relative inaccessibility, little is known about their development or incorporation into circuits. In this report we demonstrate that the GABAergic R-interneuron circuit undergoes a reorganization in the chick embryo spinal cord between embryonic days 8 and 15 (E8 and E15). R-interneurons receive synaptic input from and project back to motoneurons. By stimulating motoneurons projecting in one ventral root and recording the disynaptic response from motoneurons in adjacent segments, we show that the output of the R-interneuron circuit is reorganized during development. After stimulation of the LS2 ventral root, disynaptic responses observed in whole cell recordings became more common and stronger for LS3 motoneurons and less common for the more distant LS4 motoneurons from E8 to E10. Optical studies demonstrated that R-interneurons activated by LS2 stimulation were restricted to the LS2 segment and had a small glutamatergic component at both E8 and E10, but that more R-interneurons were activated within the segment by E10. The recruitment of more LS2 R-interneurons at E10 is likely to contribute to stronger projections to LS3 motoneurons, but the fact that fewer LS4 motoneurons receive this input is more consistent with a functional refinement of the more distant projection of the GABAergic R-interneuron. Interestingly, this pattern of reorganization was not observed throughout the rostrocaudal extent of the cord, introducing the possibility that refinement could serve to remove connections between functionally unrelated interneurons and motoneurons.
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Affiliation(s)
- Huaying Xu
- Department of Physiology, Room 601, Whitehead Bldg., Emory University, School of Medicine, Atlanta, GA, 30340, USA
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Chub N, Mentis GZ, O'donovan MJ. Chloride-sensitive MEQ fluorescence in chick embryo motoneurons following manipulations of chloride and during spontaneous network activity. J Neurophysiol 2005; 95:323-30. [PMID: 16192339 DOI: 10.1152/jn.00162.2005] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Intracellular Cl(-) ([Cl(-)](in)) homeostasis is thought to be an important regulator of spontaneous activity in the spinal cord of the chick embryo. We investigated this idea by visualizing the variations of [Cl(-)](in) in motoneurons retrogradely labeled with the Cl-sensitive dye 6-methoxy-N-ethylquinolinium iodide (MEQ) applied to cut muscle nerves in the isolated E10-E12 spinal cord. This labeling procedure obviated the need for synthesizing the reduced, cell-permeable dihydro-MEQ (DiH-MEQ). The specificity of motoneuron labeling was confirmed using retrograde co-labeling with Texas Red Dextran and immunocytochemistry for choline acetyltransferase (ChAT). In MEQ-labeled motoneurons, the GABA(A) receptor agonist isoguvacine (100 muM) increased somatic and dendritic fluorescence by 7.4 and 16.7%, respectively. The time course of this fluorescence change mirrored that of the depolarization recorded from the axons of the labeled motoneurons. Blockade of the inward Na(+)/K(-)/2Cl(-) co-transporter (NKCC1) with bumetanide (20 microM) or with a low-Na(+) bath solution (12 mM), increased MEQ fluorescence by 5.3 and 11.4%, respectively, consistent with a decrease of [Cl(-)](in). After spontaneous episodes of activity, MEQ fluorescence increased and then declined to the pre-episode level during the interepisode interval. The largest fluorescence changes occurred over motoneuron dendrites (19.7%) with significantly smaller changes (5.2%) over somata. Collectively, these results show that retrogradely loaded MEQ can be used to detect [Cl(-)](in) in motoneurons, that the bumetanide-sensitive NKCC1 co-transporter is at least partially responsible for the elevated [Cl(-)](in) of developing motoneurons, and that dendritic [Cl(-)](in) decreases during spontaneous episodes and recovers during the inter-episode interval, presumably due to the action of NKCC1.
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Affiliation(s)
- Nikolai Chub
- Laboratory of Neural Control, NINDS/NIH, Rm. 3BC911, 35 Convent Dr., Bethesda, MD 20892-3700, USA.
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Baker BJ, Kosmidis EK, Vucinic D, Falk CX, Cohen LB, Djurisic M, Zecevic D. Imaging brain activity with voltage- and calcium-sensitive dyes. Cell Mol Neurobiol 2005; 25:245-82. [PMID: 16050036 DOI: 10.1007/s10571-005-3059-6] [Citation(s) in RCA: 121] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
This paper presents three examples of imaging brain activity with voltage- or calcium-sensitive dyes and then discusses the methodological aspects of the measurements that are needed to achieve an optimal signal-to-noise ratio. Internally injected voltage-sensitive dye can be used to monitor membrane potential in the dendrites of invertebrate and vertebrate neurons in in vitro preparations. Both invertebrate and vertebrate ganglia can be bathed in voltage-sensitive dyes to stain all of the cell bodies in the preparation. These dyes can then be used to follow the spike activity of many neurons simultaneously while the preparations are generating behaviors. Calcium-sensitive dyes that are internalized into olfactory receptor neurons in the nose will, after several days, be transported to the nerve terminals of these cells in the olfactory bulb. There they can be used to measure the input from the nose to the bulb. Three kinds of noise are discussed. a. Shot noise from the random emission of photons from the preparation. b. Vibrational noise from external sources. c. Noise that occurs in the absence of light, the dark noise. Three different parts of the light measuring apparatus are discussed: the light sources, the optics, and the cameras. The major effort presently underway to improve the usefulness of optical recordings of brain activity are to find methods for staining individual cell types in the brain. Most of these efforts center around fluorescent protein sensors of activity.
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Affiliation(s)
- Bradley J Baker
- Department of Cellular and Molecular Physiology, Yale University School of Medicine, New Haven, Connecticut 06520, USA.
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Pologruto TA, Yasuda R, Svoboda K. Monitoring neural activity and [Ca2+] with genetically encoded Ca2+ indicators. J Neurosci 2005; 24:9572-9. [PMID: 15509744 PMCID: PMC6730159 DOI: 10.1523/jneurosci.2854-04.2004] [Citation(s) in RCA: 175] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Genetically encoded Ca2+ indicators (GECIs) based on fluorescent proteins (XFPs) and Ca2+-binding proteins [like calmodulin (CaM)] have great potential for the study of subcellular Ca2+ signaling and for monitoring activity in populations of neurons. However, interpreting GECI fluorescence in terms of neural activity and cytoplasmic-free Ca2+ concentration ([Ca2+]) is complicated by the nonlinear interactions between Ca2+ binding and GECI fluorescence. We have characterized GECIs in pyramidal neurons in cultured hippocampal brain slices, focusing on indicators based on circularly permuted XFPs [GCaMP (Nakai et al., 2001), Camgaroo2 (Griesbeck et al., 2001), and Inverse Pericam (Nagai et al., 2001)]. Measurements of fluorescence changes evoked by trains of action potentials revealed that GECIs have little sensitivity at low action potential frequencies compared with synthetic [Ca2+] indicators with similar affinities for Ca2+. The sensitivity of GECIs improved for high-frequency trains of action potentials, indicating that GECIs are supralinear indicators of neural activity. Simultaneous measurement of GECI fluorescence and [Ca2+] revealed supralinear relationships. We compared GECI fluorescence saturation with CaM Ca2+-dependent structural transitions. Our data suggest that GCaMP and Camgaroo2 report CaM structural transitions in the presence and absence of CaM-binding peptide, respectively.
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Affiliation(s)
- Thomas A Pologruto
- Howard Hughes Medical Institute/Cold Spring Harbor Laboratory, Cold Spring Harbor, New York 11724, USA
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O'Donovan MJ, Bonnot A, Wenner P, Mentis GZ. Calcium imaging of network function in the developing spinal cord. Cell Calcium 2005; 37:443-50. [PMID: 15820392 DOI: 10.1016/j.ceca.2005.01.012] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2004] [Accepted: 01/06/2005] [Indexed: 10/25/2022]
Abstract
We have used calcium imaging to visualize the spatiotemporal organization of activity generated by in vitro spinal cord preparations of the developing chick embryo and the neonatal mouse. During each episode of spontaneous activity, we found that chick spinal neurons were activated rhythmically and synchronously throughout the transverse extent of the spinal cord. At the onset of a spontaneous episode, optical activity originated in the ventrolateral part of the cord. Back-labeling of spinal interneurons with calcium dyes suggested that this ventrolateral initiation was mediated by activation of a class of interneurons, located dorsomedial to the motor nucleus, that receive direct monosynaptic input from motoneurons. Studies of locomotor-like activity in the anterior lumbar segments of the neonatal mouse cord revealed the existence of a rostrocaudal wave in the oscillatory component of each cycle of rhythmic motoneuron activity. This finding raises the possibility that the activation of mammalian motoneurons during locomotion may share some of the same rostrocaudally organized mechanisms that evolved to control swimming in fishes.
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Affiliation(s)
- Michael J O'Donovan
- Laboratory of Neural Control, Section on Developmental Neurobiology, NINDS, NIH, Bethesda, MD 20892, USA.
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Xu H, Whelan PJ, Wenner P. Development of an Inhibitory Interneuronal Circuit in the Embryonic Spinal Cord. J Neurophysiol 2005; 93:2922-33. [PMID: 15574794 DOI: 10.1152/jn.01091.2004] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Locally projecting inhibitory interneurons play a crucial role in the patterning and timing of network activity. However, because of their relative inaccessibility, little is known about their development or incorporation into circuits. In this study, we characterized the functional onset, neurotransmitters, rostrocaudal spread, and funicular distribution of one such spinal interneuronal circuit during development. The R-interneuron is the avian homologue of the mammalian Renshaw cell. Both cell types receive input from motoneuron recurrent collaterals and make direct connections back onto motoneurons. By stimulating motoneurons projecting in a given ventral root and recording the response in adjacent ventral roots, we demonstrate that the R-interneuron circuit becomes functional between embryonic day 6 (E6) and E7. This ventral root response is observed at E11 and at E14 until it can no longer be detected at E16. Using bath-applied neurotransmitter receptor antagonists, we were able to demonstrate that the circuit is predominately nicotinic and GABAergic from E7.5 to E15. We also found a glutamatergic component to the pathway throughout this developmental period. The R-interneuron projects three or more segments both rostrally and caudally through the ventrolateral funiculus. The distribution of this circuit may become more locally focused between E7.5 and E15.
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Affiliation(s)
- Huaying Xu
- Department of Physiology, Emory University, School of Medicine, Atlanta, GA 30340, USA
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Christie KJ, Whelan PJ. Monoaminergic establishment of rostrocaudal gradients of rhythmicity in the neonatal mouse spinal cord. J Neurophysiol 2005; 94:1554-64. [PMID: 15829596 DOI: 10.1152/jn.00299.2005] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Bath application of monoamines is a potent method for evoking locomotor activity in neonatal rats and mice. Monoamines also promote functional recovery in adult animals with spinal cord injuries by activating spinal cord networks. However, the mechanisms of their actions on spinal networks are largely unknown. In this study, we tested the hypothesis that monoamines establish rostrocaudal gradients of rhythmicity in the thoracolumbar spinal cord. Isolated neonatal mouse spinal cord preparations (P0-P2) were used. To assay excitability of networks by monoamines, we evoked a disinhibited rhythm by bath application of picrotoxin and strychnine and recorded neurograms from several thoracolumbar ventral roots. We first established that rostral and caudal segments of the thoracolumbar spinal cord had equal excitability by completely transecting preparations at the L3 segmental level and recording the frequency of the disinhibited rhythm from both segments. Next we established that a majority of ventral interneurons retrogradely labeled by calcium green dextran were active during network activity. We then bath applied combinations of monoaminergic agonists [5-HT and dopamine (DA)] known to elicit locomotor activity. Our results show that monoamines establish rostrocaudal gradients of rhythmicity in the thoracolumbar spinal cord. This may be one mechanism by which combinations of monoaminergic compounds normally stably activate locomotor networks.
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Bonnot A, Mentis GZ, Skoch J, O'Donovan MJ. Electroporation loading of calcium-sensitive dyes into the CNS. J Neurophysiol 2004; 93:1793-808. [PMID: 15509647 DOI: 10.1152/jn.00923.2004] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Calcium imaging of neural network function has been limited by the extent of tissue labeled or the time taken for labeling. We now describe the use of electroporation-an established technique for transfecting cells with genes-to load neurons with calcium-sensitive dyes in the isolated spinal cord of the neonatal mouse in vitro. The dyes were injected subdurally, intravascularly, or into the central canal. This technique results in rapid and extensive labeling of neurons and their processes at all depths of the spinal cord, over a rostrocaudal extent determined by the position and size of the electrodes. Our results suggest that vascular distribution of the dye is involved in all three types of injections. Electroporation disrupts local reflex and network function only transiently (approximately 1 h), after which time they recover. We describe applications of the method to image activity of neuronal populations and individual neurons during antidromic, reflex, and locomotor-like behaviors. We show that these different motor behaviors are characterized by distinct patterns of activation among the labeled populations of cells.
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Affiliation(s)
- Agnès Bonnot
- Laboratory of Neural Control, Section on Developmental Neurobiology, NINDS, National Institutes of Health, 35 Convent Dr., Rm. 3C1010, Bethesda, MD 20892, USA.
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Hanke J, Sabel BA. L-type calcium channel antagonist nifedipine reduces neurofilament restitution following traumatic optic nerve injury. ACTA NEUROCHIRURGICA. SUPPLEMENT 2004; 89:75-80. [PMID: 15335104 DOI: 10.1007/978-3-7091-0603-7_10] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/30/2023]
Abstract
BACKGROUND The aim of the present study was to observe if the use of the L-type calcium channel antagonist nifedipine would offer advantages for the retinal ganglion cells and the restitution of the axonal cytoskeleton after optic nerve crush. METHODS Retinal ganglion cells were retrogradely labeled with a fluorescent calcium marker. With the in vivo confocal neuroimaging (ICON) method we observed the fluorescent cell metabolism marker Oregon Green BAPTA in the same retinal ganglion cells over 3 weeks after optic nerve crush. 2 micromol nifedipine were injected intraocularly 30 minutes following optic nerve crush. FINDINGS Investigation of the optic nerve immunostained for NF-H presented decreased restitution of the neurofilaments in the axonal cytoskeleton after 3 weeks in the optic nerve crush group treated with nifedipine as compared to the optic nerve crush only group. INTERPRETATION These results show that a single injection of the calcium L-type antagonist nifedipine shortly after optic nerve injury has long-lasting negative effects on the recovery of the retinal ganglion cells.
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Affiliation(s)
- J Hanke
- Institute of Medical Psychology, Otto-von-Guericke University, Magdeburg, Germany.
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Beierlein M, Gee KR, Martin VV, Regehr WG. Presynaptic calcium measurements at physiological temperatures using a new class of dextran-conjugated indicators. J Neurophysiol 2004; 92:591-9. [PMID: 15212445 DOI: 10.1152/jn.00057.2004] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Presynaptic calcium (Ca(pre)) has been studied extensively because of its role in triggering and modulating neurotransmitter release. Although calcium regulation and calcium-driven processes can be strongly temperature dependent, technical difficulties have limited most studies of Ca(pre) to temperatures well below the physiological range. Here we assessed the use of membrane-permeant acetoxymethyl (AM) indicators and dextran-conjugated indicators for measuring Ca(pre) at physiological temperatures. A comparison of these two types of indicators loaded into parallel fibers of rat cerebellar slices revealed striking differences. AM indicators were rapidly extruded from axons and presynaptic terminals and therefore cannot be used for long-term measurements at high temperatures. In contrast, dextran-conjugated indicators were retained within parallel fibers and are therefore well suited to measuring Ca(pre) at physiological temperatures. The limited number of dextran indicators available prompted us to synthesize three new indicators that show peak emission in the red (575-600 nm). These indicators allow for simultaneous use of multiple calcium indicators that can be readily distinguished on the basis of excitation and emission wavelengths, use of excitation and emission wavelengths that are relatively insensitive to tissue autofluorescence, and measurements in systems with expression of green fluorescent protein (GFP). Thus we find that dextran-conjugated indicators are well suited to long-term recordings of Ca(pre) at physiological temperatures and that the development of new red indicators greatly extends their utility.
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Affiliation(s)
- Michael Beierlein
- Department of Neurobiology, Harvard Medical School, 220 Longwood Ave., Boston, MA 02115, USA
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O'Malley DM, Sankrithi NS, Borla MA, Parker S, Banden S, Gahtan E, Detrich HW. Optical physiology and locomotor behaviors of wild-type and nacre zebrafish. Methods Cell Biol 2004; 76:261-84. [PMID: 15602880 DOI: 10.1016/s0091-679x(04)76013-6] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Affiliation(s)
- Donald M O'Malley
- Department of Biology, Northeastern University, Boston, Massachusetts 02115, USA
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Yoshida H, Okada Y, Maruiwa H, Fukuda K, Nakamura M, Chiba K, Toyama Y. Synaptic Blockade Plays a Major Role in the Neural Disturbance of Experimental Spinal Cord Compression. J Neurotrauma 2003; 20:1365-76. [PMID: 14748984 DOI: 10.1089/089771503322686157] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
We analyzed dynamic processes of neural excitation propagation in the experimentally compressed spinal cord using a high-speed optical recording system. Transverse slices of the juvenile rat cervical spinal cord were stained with a voltage-sensitive dye (di-4-ANEPPS). Two components were identified in the depolarizing optical responses to dorsal root electrical stimulation: a fast component of short duration corresponding to pre-synaptic excitation and a slow component of long duration corresponding to post-synaptic excitation. In the directly compressed dorsal horn, the slow component was attenuated more (attenuated to 37.4 +/- 9.1% of the control) than the fast component (to 70.5 +/- 14.9%) (p < 0.01) at 400 msec after stimulation. Depolarizing optical responses to compression and to chemical synaptic blockade were similar. There was a regional difference between white matter (attenuated to 86.2 +/- 10.5%) and gray matter (to 72.6 +/- 10.4%) (p < 0.03) in compression-induced changes of the fast components; neural activity in the white matter was resistant to compression, especially in the dorsal root entry zone. Depolarizing optical signals in the region adjacent to the directly compressed site were also attenuated; the fast component was attenuated to 77.6 +/- 10.4% and the slow component to 31.8 +/- 11.3% of the control signals (p < 0.01). Spinal cord dysfunction induced by purely mechanical compression without tissue destruction was virtually restored with early decompression. We suggest that a disturbance of synaptic transmission plays an important role in the pathophysiological mechanisms of spinal cord compression, at least under in vitro experimental conditions of juvenile rats.
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Affiliation(s)
- Hideaki Yoshida
- Department of Orthopaedic Surgery, School of Medicine, Keio University, Tokyo, Japan.
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Abstract
Embryonic spontaneous activity, in the form of propagating waves, is crucial for refining visual connections. To study what aspects of this correlated activity are instructive, we must first understand how their dynamics change with development and what factors trigger their disappearance after birth. Here we report that in the turtle retina, GABA, rather than glutamate and acetylcholine, influences developmental changes in wave dynamics. Using calcium imaging of the ganglion cell layer, we report how waves switch from fast and broad, when they emerge, to slow and narrow a few days before hatching, coinciding with the emergence of excitatory GABA(A) receptor-mediated activity. Around hatching, waves gradually become stationary patches, whereas GABA(A) shifts from excitatory to inhibitory, coinciding with the upregulation of the cotransporter KCC2, suggesting that changes in intracellular chloride underlie the shift. Dark-rearing from hatching causes correlated spontaneous activity to persist, whereas GABA(A) responses remain excitatory, and KCC2 expression is weaker. We conclude that GABA plays an important regulatory role during the maturation of retinal neural activity. Using a simple and elegant mechanism, namely the switch from excitatory to inhibitory, GABA(A) receptor-mediated activity is necessary and sufficient to cause retinal waves to stop propagating, ultimately leading to the disappearance of correlated spontaneous activity. Moreover, our results suggest that visual experience modulates the GABAergic switch.
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