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Shehab S, Rehmathulla S, Javed H. A single GABA neuron receives contacts from myelinated primary afferents of two adjacent peripheral nerves. A possible role in neuropathic pain. J Comp Neurol 2018; 526:2984-2999. [PMID: 30069880 DOI: 10.1002/cne.24509] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2018] [Revised: 07/19/2018] [Accepted: 07/20/2018] [Indexed: 12/19/2022]
Abstract
GAD67-EGFP mice were used in a series of experiments to provide anatomical evidence for the role of the reduction in myelinated primary afferent input to GABA spinal neurons in the production of neuropathic pain following peripheral L5 nerve injury. First, we confirmed that L5 injury in these mice produced mechanical and thermal hyperalgesia in the ipsilateral foot. Second, we injected a mixture of cholera toxin subunit-B (CTb) and isolectin B4 (IB4) in the sciatic nerve to selectively label its myelinated and unmyelinated primary afferents. Results showed that primary afferents of sciatic nerve extend from L2-L6 spinal segments. Third, we determined the central terminations of myelinated primary afferents of L4 and L5 spinal nerves following CTb injection in either nerve. The myelinated primary afferents of both nerves terminated in the corresponding and two to three rostral spinal segments with some fibers descending to terminate in the segment caudal to the level at which they entered indicating an intermingling of their terminals at the dorsal horn of the spinal cord. Fourthly, we injected CTb in L5 nerve and CTb HRP-conjugate in L4 nerve. Confocal microscopy and subsequent image analyses showed that individual EGFP-labeled neurons in L4 segment receive myelinated primary afferent contacts from both L4 and L5 nerves. Eliminating inputs from L5 nerve following its injury would result in less involvement of spinal GABA neurons which would very likely initiate neuronal sensitization in L4 segment. This could lead to the development of hyperalgesia in response to the stimulation of the adjacent uninjured L4 nerve.
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Affiliation(s)
- Safa Shehab
- Department of Anatomy, College of Medicine and Health Sciences, United Arab Emirates University, Al-Ain, United Arab Emirates
| | - Sumisha Rehmathulla
- Department of Anatomy, College of Medicine and Health Sciences, United Arab Emirates University, Al-Ain, United Arab Emirates
| | - Hayate Javed
- Department of Anatomy, College of Medicine and Health Sciences, United Arab Emirates University, Al-Ain, United Arab Emirates
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52
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Dopamine enhances signal-to-noise ratio in cortical-brainstem encoding of aversive stimuli. Nature 2018; 563:397-401. [PMID: 30405240 PMCID: PMC6645392 DOI: 10.1038/s41586-018-0682-1] [Citation(s) in RCA: 169] [Impact Index Per Article: 28.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2016] [Accepted: 09/04/2018] [Indexed: 01/07/2023]
Abstract
Despite abundant evidence that dopamine (DA) modulates medial prefrontal cortex (mPFC) activity to mediate diverse behavioral functions1,2, the precise circuit computations remain elusive. One potentially unifying model by which DA can underlie a diversity of functions is to modulate the signal-to-noise ratio (SNR) in subpopulations of mPFC neurons3–6, where neural activity conveying sensory information (signal) is amplified relative to spontaneous firing (noise). Here, we demonstrate that DA increases the SNR of responses to aversive stimuli in mPFC neurons projecting to the dorsal periaqueductal gray (dPAG). Using electrochemical approaches, we reveal the precise time course of pinch-evoked DA release in the mPFC, and show that mPFC DA biases behavioral responses to aversive stimuli. Activation of mPFC-dPAG neurons is sufficient to drive place avoidance and defensive behaviors. mPFC-dPAG neurons displayed robust shock-induced excitations, as visualized by single-cell, projection-defined microendoscopic calcium imaging. Finally, photostimulation of DA terminals in the mPFC revealed an increase in SNR in mPFC-dPAG responses to aversive stimuli. Together, these data highlight how mPFC DA can route sensory information in a valence-specific manner to different downstream circuits.
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53
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Park JY, Park SY, Kwon H, Song Y, Yun B, Lee Y, Cho Y, Joo A, Han PL. A Group of Descending Glutamatergic Neurons Activated by Stress in Corticolimbic Regions Project to the Nucleus Accumbens. Exp Neurobiol 2018; 27:387-396. [PMID: 30429648 PMCID: PMC6221842 DOI: 10.5607/en.2018.27.5.387] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2018] [Revised: 10/02/2018] [Accepted: 10/05/2018] [Indexed: 12/20/2022] Open
Abstract
The nucleus accumbens (NAc) is the major component of the ventral striatum that regulates stress-induced depression. The NAc receives dopaminergic inputs from the ventral tegmental area (VTA), and the role of VTA-NAc neurons in stress response has been recently characterized. The NAc also receives glutamatergic inputs from various forebrain structures including the prelimbic cortex (PL), basolateral amygdala (BLA), and ventral hippocampus (vHIP), whereas the role of those glutamatergic afferents in stress response remains underscored. In the present study, we investigated the extent to which descending glutamatergic neurons activated by stress in the PL, BLA, and vHIP project to the NAc. To specifically label the input neurons into the NAc, fluorescent-tagged cholera toxin subunit B (CTB), which can be used as a retrograde neuronal tracer, was injected into the NAc. After two weeks, the mice were placed under restraint for 1 h. Subsequent histological analyses indicated that CTB-positive cells were detected in 170~680 cells/mm2 in the PL, BLA, and vHIP, and those CTB-positive cells were mostly glutamatergic. In the PL, BLA, and vHIP regions analyzed, stress-induced c-Fos expression was found in 20~100 cells/mm2. Among the CTB-positive cells, 2.6% in the PL, 4.2% in the BLA, and 1.1% in the vHIP were co-labeled by c-Fos, whereas among c-Fos-positive cells, 7.7% in the PL, 19.8% in the BLA, and 8.5% in the vHIP were co-labeled with CTB. These results suggest that the NAc receives a significant but differing proportion of glutamatergic inputs from the PL, BLA, and vHIP in stress response.
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Affiliation(s)
- Jin-Young Park
- Department of Brain and Cognitive Sciences, Ewha Womans University, Seoul 03760, Korea
| | - So Young Park
- Department of Brain and Cognitive Sciences, Ewha Womans University, Seoul 03760, Korea
| | - Hyejin Kwon
- Department of Brain and Cognitive Sciences, Ewha Womans University, Seoul 03760, Korea
| | - Yumi Song
- Department of Brain and Cognitive Sciences, Ewha Womans University, Seoul 03760, Korea
| | - Boin Yun
- Department of Brain and Cognitive Sciences, Ewha Womans University, Seoul 03760, Korea
| | - Yubin Lee
- Department of Brain and Cognitive Sciences, Ewha Womans University, Seoul 03760, Korea
| | - Yeryung Cho
- Department of Brain and Cognitive Sciences, Ewha Womans University, Seoul 03760, Korea
| | - Ahran Joo
- Department of Brain and Cognitive Sciences, Ewha Womans University, Seoul 03760, Korea
| | - Pyung-Lim Han
- Department of Brain and Cognitive Sciences, Ewha Womans University, Seoul 03760, Korea.,Department of Chemistry and Nano Science, Ewha Womans University, Seoul 03760, Korea
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54
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Yao F, Zhang E, Gao Z, Ji H, Marmouri M, Xia X. Did you choose appropriate tracer for retrograde tracing of retinal ganglion cells? The differences between cholera toxin subunit B and Fluorogold. PLoS One 2018; 13:e0205133. [PMID: 30289890 PMCID: PMC6173421 DOI: 10.1371/journal.pone.0205133] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2018] [Accepted: 09/19/2018] [Indexed: 12/31/2022] Open
Abstract
Cholera toxin subunit B (CTB) and Fluorogold(FG) are two widely utilized retrograde tracers to assess the number and function of retinal ganglion cells (RGCs). However, the relative advantages and disadvantages of these tracers remain unclear, which may lead to their inappropriate application. In this study, we compared these tracers by separately injecting the tracer into the superior Colliculi (SC) in rats, one or 2 weeks later, the rats were sacrificed, and their retinas, brains, and optic nerves were collected. From the first to second week, FG displayed a greater number of labeled RGCs and a larger diffusion area in the SC than CTB; The number of CTB labeled RGCs and the diffusion area of CTB in the SC increased significantly, but there was no distinction between FG; Furthermore, CTB exhibited more labeled RGC neurites and longer neurites than FG, but no difference was evident between the same trace; The optic nerves labeled using CTB were much clearer than those labeled using FG. In conclusion, both CTB and FG can be used for the retrograde labeling of RGCs in rats at 1 or 2 weeks. FG achieves retrograde labeling of a greater number of RGCs than CTB, whereas CTB better delineates the morphology of RGCs. Furthermore, CTB seems more suitable for retrograde labeling of some small, non-image forming nuclei in the brain to which certain RGC subtypes project their axons.
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Affiliation(s)
- Fei Yao
- Department of Ophthalmology, Xiangya Hospital, Central South University, Changsha, Hunan, China
| | - Endong Zhang
- Department of Ophthalmology, Xiangya Hospital, Central South University, Changsha, Hunan, China
| | - Zhaolin Gao
- Department of Ophthalmology, Xiangya Hospital, Central South University, Changsha, Hunan, China
| | - Hongpei Ji
- Department of Ophthalmology, The People’s Hospital of Guizhou Province, Guiyang, Guizhou, China
| | - Mahmoud Marmouri
- Department of Ophthalmology, Xiangya Hospital, Central South University, Changsha, Hunan, China
| | - Xiaobo Xia
- Department of Ophthalmology, Xiangya Hospital, Central South University, Changsha, Hunan, China
- * E-mail:
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55
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Sensory representation of an auditory cued tactile stimulus in the posterior parietal cortex of the mouse. Sci Rep 2018; 8:7739. [PMID: 29773806 PMCID: PMC5958066 DOI: 10.1038/s41598-018-25891-x] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2017] [Accepted: 04/27/2018] [Indexed: 01/01/2023] Open
Abstract
Sensory association cortices receive diverse inputs with their role in representing and integrating multi-sensory content remaining unclear. Here we examined the neuronal correlates of an auditory-tactile stimulus sequence in the posterior parietal cortex (PPC) using 2-photon calcium imaging in awake mice. We find that neuronal subpopulations in layer 2/3 of PPC reliably represent texture-touch events, in addition to auditory cues that presage the incoming tactile stimulus. Notably, altering the flow of sensory events through omission of the cued texture touch elicited large responses in a subset of neurons hardly responsive to or even inhibited by the tactile stimuli. Hence, PPC neurons were able to discriminate not only tactile stimulus features (i.e., texture graininess) but also between the presence and omission of the texture stimulus. Whereas some of the neurons responsive to texture omission were driven by looming-like auditory sounds others became recruited only with tactile sensory experience. These findings indicate that layer 2/3 neuronal populations in PPC potentially encode correlates of expectancy in addition to auditory and tactile stimuli.
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56
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Sharma SK, Seven ES, Micic M, Li S, Leblanc RM. Surface Chemistry and Spectroscopic Study of a Cholera Toxin B Langmuir Monolayer. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2018; 34:2557-2564. [PMID: 29378405 DOI: 10.1021/acs.langmuir.7b04252] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
In this article, we explored the surface chemistry properties of a cholera toxin B (CTB) monolayer at the air-subphase interface and investigated the change in interfacial properties through in situ spectroscopy. The study showed that the impact of the blue shift was negligible, suggesting that the CTB molecules were minimally affected by the subphase molecules. The stability of the CTB monolayer was studied by maintaining the constant surface pressure for a long time and also by using the compression-decompression cycle experiments. The high stability of the Langmuir monolayer of CTB clearly showed that the driving force of CTB going to the amphiphilic membrane was its amphiphilic nature. In addition, no major change was detected in the various in situ spectroscopy results (such as UV-vis, fluorescence, and IR ER) of the CTB Langmuir monolayer with the increase in surface pressure. This indicates that no aggregation occurs in the Langmuir monolayer of CTB.
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Affiliation(s)
- Shiv K Sharma
- Department of Chemistry, University of Miami , 1301 Memorial Drive, Coral Gables, Florida 33146, United States
| | - Elif S Seven
- Department of Chemistry, University of Miami , 1301 Memorial Drive, Coral Gables, Florida 33146, United States
| | - Miodrag Micic
- MP Biomedicals LLC, 3 Hutton Center, Santa Ana, California 92707, United States
- Department of Engineering Design Technology, Cerritos College , 11110 Alondra Boulevard, Norwalk, California 90650, United States
| | - Shanghao Li
- MP Biomedicals LLC, 3 Hutton Center, Santa Ana, California 92707, United States
| | - Roger M Leblanc
- Department of Chemistry, University of Miami , 1301 Memorial Drive, Coral Gables, Florida 33146, United States
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57
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Tröster P, Haseleu J, Petersen J, Drees O, Schmidtko A, Schwaller F, Lewin GR, Ter-Avetisyan G, Winter Y, Peters S, Feil S, Feil R, Rathjen FG, Schmidt H. The Absence of Sensory Axon Bifurcation Affects Nociception and Termination Fields of Afferents in the Spinal Cord. Front Mol Neurosci 2018; 11:19. [PMID: 29472841 PMCID: PMC5809486 DOI: 10.3389/fnmol.2018.00019] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2017] [Accepted: 01/15/2018] [Indexed: 12/16/2022] Open
Abstract
A cGMP signaling cascade composed of C-type natriuretic peptide, the guanylyl cyclase receptor Npr2 and cGMP-dependent protein kinase I (cGKI) controls the bifurcation of sensory axons upon entering the spinal cord during embryonic development. However, the impact of axon bifurcation on sensory processing in adulthood remains poorly understood. To investigate the functional consequences of impaired axon bifurcation during adult stages we generated conditional mouse mutants of Npr2 and cGKI (Npr2fl/fl;Wnt1Cre and cGKIKO/fl;Wnt1Cre) that lack sensory axon bifurcation in the absence of additional phenotypes observed in the global knockout mice. Cholera toxin labeling in digits of the hind paw demonstrated an altered shape of sensory neuron termination fields in the spinal cord of conditional Npr2 mouse mutants. Behavioral testing of both sexes indicated that noxious heat sensation and nociception induced by chemical irritants are impaired in the mutants, whereas responses to cold sensation, mechanical stimulation, and motor coordination are not affected. Recordings from C-fiber nociceptors in the hind limb skin showed that Npr2 function was not required to maintain normal heat sensitivity of peripheral nociceptors. Thus, the altered behavioral responses to noxious heat found in Npr2fl/fl;Wnt1Cre mice is not due to an impaired C-fiber function. Overall, these data point to a critical role of axonal bifurcation for the processing of pain induced by heat or chemical stimuli.
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Affiliation(s)
- Philip Tröster
- Developmental Neurobiology, Max Delbrück Center for Molecular Medicine in the Helmholtz Association, Berlin, Germany
| | - Julia Haseleu
- Molecular Physiology of Somatic Sensation, Max Delbrück Center for Molecular Medicine in the Helmholtz Association, Berlin, Germany
| | - Jonas Petersen
- Institute of Pharmacology, College of Pharmacy, Goethe University, Frankfurt am Main, Germany.,Institute of Pharmacology and Toxicology, Zentrum für Biomedizinische Ausbildung und Forschung (ZBAF), Witten/Herdecke University, Witten, Germany
| | - Oliver Drees
- Institute of Pharmacology and Toxicology, Zentrum für Biomedizinische Ausbildung und Forschung (ZBAF), Witten/Herdecke University, Witten, Germany
| | - Achim Schmidtko
- Institute of Pharmacology, College of Pharmacy, Goethe University, Frankfurt am Main, Germany.,Institute of Pharmacology and Toxicology, Zentrum für Biomedizinische Ausbildung und Forschung (ZBAF), Witten/Herdecke University, Witten, Germany
| | - Frederick Schwaller
- Molecular Physiology of Somatic Sensation, Max Delbrück Center for Molecular Medicine in the Helmholtz Association, Berlin, Germany
| | - Gary R Lewin
- Molecular Physiology of Somatic Sensation, Max Delbrück Center for Molecular Medicine in the Helmholtz Association, Berlin, Germany
| | - Gohar Ter-Avetisyan
- Developmental Neurobiology, Max Delbrück Center for Molecular Medicine in the Helmholtz Association, Berlin, Germany
| | - York Winter
- Cognitive Neurobiology, Humboldt University of Berlin, Berlin, Germany
| | - Stefanie Peters
- Interfaculty Institute of Biochemistry, University of Tübingen, Tübingen, Germany
| | - Susanne Feil
- Interfaculty Institute of Biochemistry, University of Tübingen, Tübingen, Germany
| | - Robert Feil
- Interfaculty Institute of Biochemistry, University of Tübingen, Tübingen, Germany
| | - Fritz G Rathjen
- Developmental Neurobiology, Max Delbrück Center for Molecular Medicine in the Helmholtz Association, Berlin, Germany
| | - Hannes Schmidt
- Developmental Neurobiology, Max Delbrück Center for Molecular Medicine in the Helmholtz Association, Berlin, Germany
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58
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Sellers KK, Yu C, Zhou ZC, Stitt I, Li Y, Radtke-Schuller S, Alagapan S, Fröhlich F. Oscillatory Dynamics in the Frontoparietal Attention Network during Sustained Attention in the Ferret. Cell Rep 2017; 16:2864-2874. [PMID: 27626658 DOI: 10.1016/j.celrep.2016.08.055] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2016] [Revised: 07/15/2016] [Accepted: 08/17/2016] [Indexed: 01/08/2023] Open
Abstract
Sustained attention requires the coordination of neural activity across multiple cortical areas in the frontoparietal network, in particular the prefrontal cortex (PFC) and posterior parietal cortex (PPC). Previous work has demonstrated that activity in these brain regions is coordinated by neuronal oscillations of the local field potential (LFP). However, the underlying coordination of activity in terms of organization of single unit (SU) spiking activity has remained poorly understood, particularly in the freely moving animal. We found that long-range functional connectivity between anatomically connected PFC and PPC was mediated by oscillations in the theta frequency band. SU activity in PFC was phase locked to theta oscillations in PPC, and spiking activity in PFC and PPC was locked to local high-gamma activity. Together, our results support a model in which frequency-specific synchronization mediates functional connectivity between and within PFC and PPC of the frontoparietal attention network in the freely moving animal.
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Affiliation(s)
- Kristin K Sellers
- Department of Psychiatry, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA; Neurobiology Curriculum, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Chunxiu Yu
- Department of Psychiatry, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Zhe Charles Zhou
- Department of Psychiatry, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA; Neurobiology Curriculum, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Iain Stitt
- Department of Psychiatry, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Yuhui Li
- Department of Psychiatry, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Susanne Radtke-Schuller
- Department of Psychiatry, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Sankaraleengam Alagapan
- Department of Psychiatry, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Flavio Fröhlich
- Department of Psychiatry, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA; Neurobiology Curriculum, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA; Department of Cell Biology and Physiology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA; Department of Biomedical Engineering, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA; Neuroscience Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA; Department of Neurology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA.
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59
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Diepenbroek C, Quinn D, Stephens R, Zollinger B, Anderson S, Pan A, de Lartigue G. Validation and characterization of a novel method for selective vagal deafferentation of the gut. Am J Physiol Gastrointest Liver Physiol 2017; 313:G342-G352. [PMID: 28705805 PMCID: PMC5668568 DOI: 10.1152/ajpgi.00095.2017] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/24/2017] [Revised: 06/01/2017] [Accepted: 06/23/2017] [Indexed: 01/31/2023]
Abstract
There is a lack of tools that selectively target vagal afferent neurons (VAN) innervating the gut. We use saporin (SAP), a potent neurotoxin, conjugated to the gastronintestinal (GI) hormone cholecystokinin (CCK-SAP) injected into the nodose ganglia (NG) of male Wistar rats to specifically ablate GI-VAN. We report that CCK-SAP ablates a subpopulation of VAN in culture. In vivo, CCK-SAP injection into the NG reduces VAN innervating the mucosal and muscular layers of the stomach and small intestine but not the colon, while leaving vagal efferent neurons intact. CCK-SAP abolishes feeding-induced c-Fos in the NTS, as well as satiation by CCK or glucagon like peptide-1 (GLP-1). CCK-SAP in the NG of mice also abolishes CCK-induced satiation. Therefore, we provide multiple lines of evidence that injection of CCK-SAP in NG is a novel selective vagal deafferentation technique of the upper GI tract that works in multiple vertebrate models. This method provides improved tissue specificity and superior separation of afferent and efferent signaling compared with vagotomy, capsaicin, and subdiaphragmatic deafferentation.NEW & NOTEWORTHY We develop a new method that allows targeted lesioning of vagal afferent neurons that innervate the upper GI tract while sparing vagal efferent neurons. This reliable approach provides superior tissue specificity and selectivity for vagal afferent over efferent targeting than traditional approaches. It can be used to address questions about the role of gut to brain signaling in physiological and pathophysiological conditions.
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Affiliation(s)
- Charlene Diepenbroek
- The John B. Pierce Laboratory, New Haven, Connecticut
- Department of Cellular and Molecular Physiology, Yale Medical School, New Haven, Connecticut; and
| | | | - Ricky Stephens
- Department of Anatomy, Physiology, and Cell Biology, University of California Davis, Davis, California
| | | | - Seth Anderson
- The John B. Pierce Laboratory, New Haven, Connecticut
| | - Annabelle Pan
- The John B. Pierce Laboratory, New Haven, Connecticut
| | - Guillaume de Lartigue
- The John B. Pierce Laboratory, New Haven, Connecticut;
- Department of Cellular and Molecular Physiology, Yale Medical School, New Haven, Connecticut; and
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60
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Kamitakahara A, Wu HH, Levitt P. Distinct projection targets define subpopulations of mouse brainstem vagal neurons that express the autism-associated MET receptor tyrosine kinase. J Comp Neurol 2017; 525:3787-3808. [PMID: 28758209 DOI: 10.1002/cne.24294] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2017] [Revised: 07/14/2017] [Accepted: 07/17/2017] [Indexed: 12/11/2022]
Abstract
Detailed anatomical tracing and mapping of the viscerotopic organization of the vagal motor nuclei has provided insight into autonomic function in health and disease. To further define specific cellular identities, we paired information based on visceral connectivity with a cell-type specific marker of a subpopulation of neurons in the dorsal motor nucleus of the vagus (DMV) and nucleus ambiguus (nAmb) that express the autism-associated MET receptor tyrosine kinase. As gastrointestinal disturbances are common in children with autism spectrum disorder (ASD), we sought to define the relationship between MET-expressing (MET+) neurons in the DMV and nAmb, and the gastrointestinal tract. Using wholemount tissue staining and clearing, or retrograde tracing in a METEGFP transgenic mouse, we identify three novel subpopulations of EGFP+ vagal brainstem neurons: (a) EGFP+ neurons in the nAmb projecting to the esophagus or laryngeal muscles, (b) EGFP+ neurons in the medial DMV projecting to the stomach, and (b) EGFP+ neurons in the lateral DMV projecting to the cecum and/or proximal colon. Expression of the MET ligand, hepatocyte growth factor (HGF), by tissues innervated by vagal motor neurons during fetal development reveal potential sites of HGF-MET interaction. Furthermore, similar cellular expression patterns of MET in the brainstem of both the mouse and nonhuman primate suggests that MET expression at these sites is evolutionarily conserved. Together, the data suggest that MET+ neurons in the brainstem vagal motor nuclei are anatomically positioned to regulate distinct portions of the gastrointestinal tract, with implications for the pathophysiology of gastrointestinal comorbidities of ASD.
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Affiliation(s)
- Anna Kamitakahara
- Program in Developmental Neurogenetics, Institute for the Developing Mind, The Saban Resarch Institute, Children's Hospital Los Angeles, Los Angeles, California
| | - Hsiao-Huei Wu
- Keck School of Medicine of University of Southern California, Los Angeles, California
| | - Pat Levitt
- Program in Developmental Neurogenetics, Institute for the Developing Mind, The Saban Resarch Institute, Children's Hospital Los Angeles, Los Angeles, California.,Department of Pediatrics, Keck School of Medicine of University of Southern California, Los Angeles, California.,University of Southern California Program in Neuroscience, Los Angeles, California
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61
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McCall JG, Siuda ER, Bhatti DL, Lawson LA, McElligott ZA, Stuber GD, Bruchas MR. Locus coeruleus to basolateral amygdala noradrenergic projections promote anxiety-like behavior. eLife 2017; 6. [PMID: 28708061 PMCID: PMC5550275 DOI: 10.7554/elife.18247] [Citation(s) in RCA: 178] [Impact Index Per Article: 25.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2016] [Accepted: 07/13/2017] [Indexed: 01/01/2023] Open
Abstract
Increased tonic activity of locus coeruleus noradrenergic (LC-NE) neurons induces anxiety-like and aversive behavior. While some information is known about the afferent circuitry that endogenously drives this neural activity and behavior, the downstream receptors and anatomical projections that mediate these acute risk aversive behavioral states via the LC-NE system remain unresolved. Here we use a combination of retrograde tracing, fast-scan cyclic voltammetry, electrophysiology, and in vivo optogenetics with localized pharmacology to identify neural substrates downstream of increased tonic LC-NE activity in mice. We demonstrate that photostimulation of LC-NE fibers in the BLA evokes norepinephrine release in the basolateral amygdala (BLA), alters BLA neuronal activity, conditions aversion, and increases anxiety-like behavior. Additionally, we report that β-adrenergic receptors mediate the anxiety-like phenotype of increased NE release in the BLA. These studies begin to illustrate how the complex efferent system of the LC-NE system selectively mediates behavior through distinct receptor and projection-selective mechanisms. DOI:http://dx.doi.org/10.7554/eLife.18247.001
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Affiliation(s)
- Jordan G McCall
- Department of Anesthesiology, Division of Basic Research, Washington University School of Medicine, St. Louis, United States.,Washington University Pain Center, Washington University School of Medicine, St. Louis, United States.,Department of Neuroscience, Washington University School of Medicine, St. Louis, United States.,Division of Biology and Biomedical Sciences, Washington University School of Medicine, St. Louis, United States
| | - Edward R Siuda
- Department of Anesthesiology, Division of Basic Research, Washington University School of Medicine, St. Louis, United States.,Washington University Pain Center, Washington University School of Medicine, St. Louis, United States.,Department of Neuroscience, Washington University School of Medicine, St. Louis, United States.,Division of Biology and Biomedical Sciences, Washington University School of Medicine, St. Louis, United States
| | - Dionnet L Bhatti
- Department of Anesthesiology, Division of Basic Research, Washington University School of Medicine, St. Louis, United States.,Division of Biology and Biomedical Sciences, Washington University School of Medicine, St. Louis, United States
| | - Lamley A Lawson
- Department of Anesthesiology, Division of Basic Research, Washington University School of Medicine, St. Louis, United States
| | - Zoe A McElligott
- Department of Psychiatry, University of North Carolina, Chapel Hill, United States.,Bowles Center for Alcohol Studies, University of North Carolina, Chapel Hill, United States
| | - Garret D Stuber
- Department of Psychiatry, University of North Carolina, Chapel Hill, United States.,Department of Cell Biology and Physiology, University of North Carolina, Chapel Hill, United States.,Neuroscience Center, University of North Carolina, Chapel Hill, United States
| | - Michael R Bruchas
- Department of Anesthesiology, Division of Basic Research, Washington University School of Medicine, St. Louis, United States.,Washington University Pain Center, Washington University School of Medicine, St. Louis, United States.,Department of Neuroscience, Washington University School of Medicine, St. Louis, United States.,Division of Biology and Biomedical Sciences, Washington University School of Medicine, St. Louis, United States.,Department of Biomedical Engineering, Washington University, St. Louis, United States
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62
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Selective Motor Neuron Resistance and Recovery in a New Inducible Mouse Model of TDP-43 Proteinopathy. J Neurosci 2017; 36:7707-17. [PMID: 27445147 DOI: 10.1523/jneurosci.1457-16.2016] [Citation(s) in RCA: 57] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2016] [Accepted: 06/09/2016] [Indexed: 12/12/2022] Open
Abstract
UNLABELLED Motor neurons (MNs) are the neuronal class that is principally affected in amyotrophic lateral sclerosis (ALS), but it is widely known that individual motor pools do not succumb to degeneration simultaneously. Because >90% of ALS patients have an accumulation of cytoplasmic TDP-43 aggregates in postmortem brain and spinal cord (SC), it has been suggested that these inclusions in a given population may trigger its death. We investigated seven MN pools in our new inducible rNLS8 transgenic (Tg) mouse model of TDP-43 proteinopathy and found striking differences in MN responses to TDP-43 pathology. Despite widespread neuronal expression of cytoplasmic human TDP-43, only MNs in the hypoglossal nucleus and the SC are lost after 8 weeks of transgene expression, whereas those in the oculomotor, trigeminal, and facial nuclei are spared. Within the SC, slow MNs survive to end stage, whereas fast fatigable MNs are lost. Correspondingly, axonal dieback occurs first from fast-twitch muscle fibers, whereas slow-twitch fibers remain innervated. Individual pools show differences in the downregulation of endogenous nuclear TDP-43, but this does not fully account for vulnerability to degenerate. After transgene suppression, resistant MNs sprout collaterals to reinnervate previously denervated neuromuscular junctions concurrently with expression of matrix metalloproteinase 9 (MMP-9), a marker of fast MNs. Therefore, although pathological TDP-43 is linked to MN degeneration, the process is not stochastic and mirrors the highly selective patterns of MN degeneration observed in ALS patients. SIGNIFICANCE STATEMENT Because TDP-43 is the major pathological hallmark of amyotrophic lateral sclerosis (ALS), we generated mice in which mutant human TDP-43 expression causes progressive neuron loss. We show that these rNLS8 mice have a pattern of axonal dieback and cell death that mirrors that often observed in human patients. This finding demonstrates the diversity of motor neuron (MN) populations in their response to pathological TDP-43. Furthermore, we demonstrate that resistant MNs are able to compensate for the loss of their more vulnerable counterparts and change their phenotype in the process. These findings are important because using a mouse model that closely models human ALS in both the disease pathology and the pattern of degeneration is critical to studying and eventually treating progressive paralysis in ALS patients.
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63
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Maurer AP, Johnson SA, Hernandez AR, Reasor J, Cossio DM, Fertal KE, Mizell JM, Lubke KN, Clark BJ, Burke SN. Age-related Changes in Lateral Entorhinal and CA3 Neuron Allocation Predict Poor Performance on Object Discrimination. Front Syst Neurosci 2017; 11:49. [PMID: 28713251 PMCID: PMC5491840 DOI: 10.3389/fnsys.2017.00049] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2017] [Accepted: 06/19/2017] [Indexed: 11/24/2022] Open
Abstract
Age-related memory deficits correlate with dysfunction in the CA3 subregion of the hippocampus, which includes both hyperactivity and overly rigid activity patterns. While changes in intrinsic membrane currents and interneuron alterations are involved in this process, it is not known whether alterations in afferent input to CA3 also contribute. Neurons in layer II of the lateral entorhinal cortex (LEC) project directly to CA3 through the perforant path, but no data are available regarding the effects of advanced age on LEC activity and whether these activity patterns update in response to environmental change. Furthermore, it is not known the extent to which age-related deficits in sensory discrimination relate to the inability of aged CA3 neurons to update in response to new environments. Young and aged rats were pre-characterized on a LEGO© object discrimination task, comparable to behavioral tests in humans in which CA3 hyperactivity has been linked to impairments. The cellular compartment analysis of temporal activity with fluorescence in situ hybridization for the immediate-early gene Arc was then used to identify the principal cell populations that were active during two distinct epochs of random foraging in different environments. This approach enabled the extent to which rats could discriminate two similar objects to be related to the ability of CA3 neurons to update across different environments. In both young and aged rats, there were animals that performed poorly on the LEGO object discrimination task. In the aged rats only, however, the poor performers had a higher percent of CA3 neurons that were active during random foraging in a novel environment, but this is not related to the ability of CA3 neurons to remap when the environment changed. Afferent neurons to CA3 in LEC, as identified with the retrograde tracer choleratoxin B (CTB), also showed a higher percentage of cells that were positive for Arc mRNA in aged poor performing rats. This suggests that LEC contributes to the hyperactivity seen in CA3 of aged animals with object discrimination deficits and age-related cognitive decline may be the consequence of dysfunction endemic to the larger network.
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Affiliation(s)
- Andrew P Maurer
- Department of Neuroscience, McKnight Brain Institute, University of FloridaGainesville, FL, United States.,Department of Biomedical Engineering, University of FloridaGainesville, FL, United States
| | - Sarah A Johnson
- Department of Neuroscience, McKnight Brain Institute, University of FloridaGainesville, FL, United States
| | - Abbi R Hernandez
- Department of Neuroscience, McKnight Brain Institute, University of FloridaGainesville, FL, United States
| | - Jordan Reasor
- Department of Neuroscience, McKnight Brain Institute, University of FloridaGainesville, FL, United States
| | - Daniela M Cossio
- Department of Neuroscience, McKnight Brain Institute, University of FloridaGainesville, FL, United States.,UF Summer Neuroscience Internship Program, Department of Neuroscience, McKnight Brain Institute, University of FloridaGainesville, FL, United States
| | - Kaeli E Fertal
- Department of Neuroscience, McKnight Brain Institute, University of FloridaGainesville, FL, United States
| | - Jack M Mizell
- Department of Neuroscience, McKnight Brain Institute, University of FloridaGainesville, FL, United States
| | - Katelyn N Lubke
- Department of Neuroscience, McKnight Brain Institute, University of FloridaGainesville, FL, United States.,Department of Biomedical Engineering, University of FloridaGainesville, FL, United States
| | - Benjamin J Clark
- Department of Psychology, University of New MexicoAlburquerque, NM, United States
| | - Sara N Burke
- Department of Neuroscience, McKnight Brain Institute, University of FloridaGainesville, FL, United States.,Department of Aging and Geriatric Research, UF Institute on Aging, University of FloridaGainesville, FL, United States
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64
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Yang NJ, Chiu IM. Bacterial Signaling to the Nervous System through Toxins and Metabolites. J Mol Biol 2017; 429:587-605. [PMID: 28065740 PMCID: PMC5325782 DOI: 10.1016/j.jmb.2016.12.023] [Citation(s) in RCA: 102] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2016] [Revised: 12/21/2016] [Accepted: 12/29/2016] [Indexed: 12/31/2022]
Abstract
Mammalian hosts interface intimately with commensal and pathogenic bacteria. It is increasingly clear that molecular interactions between the nervous system and microbes contribute to health and disease. Both commensal and pathogenic bacteria are capable of producing molecules that act on neurons and affect essential aspects of host physiology. Here we highlight several classes of physiologically important molecular interactions that occur between bacteria and the nervous system. First, clostridial neurotoxins block neurotransmission to or from neurons by targeting the SNARE complex, causing the characteristic paralyses of botulism and tetanus during bacterial infection. Second, peripheral sensory neurons-olfactory chemosensory neurons and nociceptor sensory neurons-detect bacterial toxins, formyl peptides, and lipopolysaccharides through distinct molecular mechanisms to elicit smell and pain. Bacteria also damage the central nervous system through toxins that target the brain during infection. Finally, the gut microbiota produces molecules that act on enteric neurons to influence gastrointestinal motility, and metabolites that stimulate the "gut-brain axis" to alter neural circuits, autonomic function, and higher-order brain function and behavior. Furthering the mechanistic and molecular understanding of how bacteria affect the nervous system may uncover potential strategies for modulating neural function and treating neurological diseases.
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Affiliation(s)
- Nicole J Yang
- Department of Microbiology and Immunobiology, Division of Immunology, Harvard Medical School, Boston, MA 02115, USA
| | - Isaac M Chiu
- Department of Microbiology and Immunobiology, Division of Immunology, Harvard Medical School, Boston, MA 02115, USA.
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65
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Prefrontal cortex output circuits guide reward seeking through divergent cue encoding. Nature 2017; 543:103-107. [PMID: 28225752 PMCID: PMC5772935 DOI: 10.1038/nature21376] [Citation(s) in RCA: 258] [Impact Index Per Article: 36.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2016] [Accepted: 01/10/2017] [Indexed: 12/19/2022]
Abstract
The prefrontal cortex is a critical neuroanatomical hub for controlling motivated behaviours across mammalian species. In addition to intra-cortical connectivity, prefrontal projection neurons innervate subcortical structures that contribute to reward-seeking behaviours, such as the ventral striatum and midline thalamus. While connectivity among these structures contributes to appetitive behaviours, how projection-specific prefrontal neurons encode reward-relevant information to guide reward seeking is unknown. Here we use in vivo two-photon calcium imaging to monitor the activity of dorsomedial prefrontal neurons in mice during an appetitive Pavlovian conditioning task. At the population level, these neurons display diverse activity patterns during the presentation of reward-predictive cues. However, recordings from prefrontal neurons with resolved projection targets reveal that individual corticostriatal neurons show response tuning to reward-predictive cues, such that excitatory cue responses are amplified across learning. By contrast, corticothalamic neurons gradually develop new, primarily inhibitory responses to reward-predictive cues across learning. Furthermore, bidirectional optogenetic manipulation of these neurons reveals that stimulation of corticostriatal neurons promotes conditioned reward-seeking behaviour after learning, while activity in corticothalamic neurons suppresses both the acquisition and expression of conditioned reward seeking. These data show how prefrontal circuitry can dynamically control reward-seeking behaviour through the opposing activities of projection-specific cell populations.
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66
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Preparation and implementation of optofluidic neural probes for in vivo wireless pharmacology and optogenetics. Nat Protoc 2017; 12:219-237. [PMID: 28055036 DOI: 10.1038/nprot.2016.155] [Citation(s) in RCA: 50] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
This Protocol Extension describes the fabrication and technical procedures for implementing ultrathin, flexible optofluidic neural probe systems that provide targeted, wireless delivery of fluids and light into the brains of awake, freely behaving animals. As a Protocol Extension article, this article describes an adaptation of an existing Protocol that offers additional applications. This protocol serves as an extension of an existing Nature Protocol describing optoelectronic devices for studying intact neural systems. Here, we describe additional features of fabricating self-contained platforms that involve flexible microfluidic probes, pumping systems, microscale inorganic LEDs, wireless-control electronics, and power supplies. These small, flexible probes minimize tissue damage and inflammation, making long-term implantation possible. The capabilities include wireless pharmacological and optical intervention for dissecting neural circuitry during behavior. The fabrication can be completed in 1-2 weeks, and the devices can be used for 1-2 weeks of in vivo rodent experiments. To successfully carry out the protocol, researchers should have basic skill sets in photolithography and soft lithography, as well as experience with stereotaxic surgery and behavioral neuroscience practices. These fabrication processes and implementation protocols will increase access to wireless optofluidic neural probes for advanced in vivo pharmacology and optogenetics in freely moving rodents.This protocol is an extension to: Nat. Protoc. 8, 2413-2428 (2013); doi:10.1038/nprot.2013.158; published online 07 November 2013.
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67
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Abstract
The homeostatic control of body temperature is essential for survival in mammals and is known to be regulated in part by temperature-sensitive neurons in the hypothalamus. However, the specific neural pathways and corresponding neural populations have not been fully elucidated. To identify these pathways, we used cFos staining to identify neurons that are activated by a thermal challenge and found induced expression in subsets of neurons within the ventral part of the lateral preoptic nucleus (vLPO) and the dorsal part of the dorsomedial hypothalamus (DMD). Activation of GABAergic neurons in the vLPO using optogenetics reduced body temperature, along with a decrease in physical activity. Optogenetic inhibition of these neurons resulted in fever-level hyperthermia. These GABAergic neurons project from the vLPO to the DMD and optogenetic stimulation of the nerve terminals in the DMD also reduced body temperature and activity. Electrophysiological recording revealed that the vLPO GABAergic neurons suppressed neural activity in DMD neurons, and fiber photometry of calcium transients revealed that DMD neurons were activated by cold. Accordingly, activation of DMD neurons using designer receptors exclusively activated by designer drugs (DREADDs) or optogenetics increased body temperature with a strong increase in energy expenditure and activity. Finally, optogenetic inhibition of DMD neurons triggered hypothermia, similar to stimulation of the GABAergic neurons in the vLPO. Thus, vLPO GABAergic neurons suppressed the thermogenic effect of DMD neurons. In aggregate, our data identify vLPO→DMD neural pathways that reduce core temperature in response to a thermal challenge, and we show that outputs from the DMD can induce activity-induced thermogenesis.
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68
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Todd TP, Mehlman ML, Keene CS, DeAngeli NE, Bucci DJ. Retrosplenial cortex is required for the retrieval of remote memory for auditory cues. ACTA ACUST UNITED AC 2016; 23:278-88. [PMID: 27194795 PMCID: PMC4880149 DOI: 10.1101/lm.041822.116] [Citation(s) in RCA: 60] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2016] [Accepted: 03/07/2016] [Indexed: 11/25/2022]
Abstract
The restrosplenial cortex (RSC) has a well-established role in contextual and spatial learning and memory, consistent with its known connectivity with visuo-spatial association areas. In contrast, RSC appears to have little involvement with delay fear conditioning to an auditory cue. However, all previous studies have examined the contribution of the RSC to recently acquired auditory fear memories. Since neocortical regions have been implicated in the permanent storage of remote memories, we examined the contribution of the RSC to remotely acquired auditory fear memories. In Experiment 1, retrieval of a remotely acquired auditory fear memory was impaired when permanent lesions (either electrolytic or neurotoxic) were made several weeks after initial conditioning. In Experiment 2, using a chemogenetic approach, we observed impairments in the retrieval of remote memory for an auditory cue when the RSC was temporarily inactivated during testing. In Experiment 3, after injection of a retrograde tracer into the RSC, we observed labeled cells in primary and secondary auditory cortices, as well as the claustrum, indicating that the RSC receives direct projections from auditory regions. Overall our results indicate the RSC has a critical role in the retrieval of remotely acquired auditory fear memories, and we suggest this is related to the quality of the memory, with less precise memories being RSC dependent.
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Affiliation(s)
- Travis P Todd
- Department of Psychological and Brain Sciences, Dartmouth College, Hanover, New Hampshire 03755, USA
| | - Max L Mehlman
- Department of Psychological and Brain Sciences, Dartmouth College, Hanover, New Hampshire 03755, USA
| | - Christopher S Keene
- Department of Psychological and Brain Sciences, Dartmouth College, Hanover, New Hampshire 03755, USA
| | - Nicole E DeAngeli
- Department of Psychological and Brain Sciences, Dartmouth College, Hanover, New Hampshire 03755, USA
| | - David J Bucci
- Department of Psychological and Brain Sciences, Dartmouth College, Hanover, New Hampshire 03755, USA
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69
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Wasserman DI, Tan JMJ, Kim JC, Yeomans JS. Muscarinic control of rostromedial tegmental nucleus GABA neurons and morphine-induced locomotion. Eur J Neurosci 2016; 44:1761-70. [DOI: 10.1111/ejn.13237] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2015] [Revised: 02/20/2016] [Accepted: 03/10/2016] [Indexed: 11/28/2022]
Affiliation(s)
- David I. Wasserman
- Department of Psychology; University of Toronto; Toronto ON Canada
- Department of Psychology; University of Guelph; Guelph ON N1G 2W1 Canada
| | - Joel M. J. Tan
- Department of Psychology; University of Toronto; Toronto ON Canada
| | - Jun Chul Kim
- Department of Psychology; University of Toronto; Toronto ON Canada
| | - John S. Yeomans
- Department of Psychology; University of Toronto; Toronto ON Canada
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70
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Lerner TN, Ye L, Deisseroth K. Communication in Neural Circuits: Tools, Opportunities, and Challenges. Cell 2016; 164:1136-1150. [PMID: 26967281 PMCID: PMC5725393 DOI: 10.1016/j.cell.2016.02.027] [Citation(s) in RCA: 109] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2015] [Revised: 01/27/2016] [Accepted: 02/03/2016] [Indexed: 11/27/2022]
Abstract
Communication, the effective delivery of information, is fundamental to life across all scales and species. Nervous systems (by necessity) may be most specifically adapted among biological tissues for high rate and complexity of information transmitted, and thus, the properties of neural tissue and principles of its organization into circuits may illuminate capabilities and limitations of biological communication. Here, we consider recent developments in tools for studying neural circuits with particular attention to defining neuronal cell types by input and output information streams--i.e., by how they communicate. Complementing approaches that define cell types by virtue of genetic promoter/enhancer properties, this communication-based approach to defining cell types operationally by input/output (I/O) relationships links structure and function, resolves difficulties associated with single-genetic-feature definitions, leverages technology for observing and testing significance of precisely these I/O relationships in intact brains, and maps onto processes through which behavior may be adapted during development, experience, and evolution.
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Affiliation(s)
- Talia N Lerner
- Bioengineering Department, 318 Campus Drive, Stanford University, Stanford, CA 94305, USA
| | - Li Ye
- Bioengineering Department, 318 Campus Drive, Stanford University, Stanford, CA 94305, USA
| | - Karl Deisseroth
- Bioengineering Department, 318 Campus Drive, Stanford University, Stanford, CA 94305, USA; Psychiatry Department, 318 Campus Drive, Stanford University, Stanford, CA 94305, USA; Howard Hughes Medical Institute, 318 Campus Drive, Stanford University, Stanford, CA 94305, USA.
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71
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Hogstrom LJ, Guo SM, Murugadoss K, Bathe M. Advancing multiscale structural mapping of the brain through fluorescence imaging and analysis across length scales. Interface Focus 2016; 6:20150081. [PMID: 26855758 DOI: 10.1098/rsfs.2015.0081] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Brain function emerges from hierarchical neuronal structure that spans orders of magnitude in length scale, from the nanometre-scale organization of synaptic proteins to the macroscopic wiring of neuronal circuits. Because the synaptic electrochemical signal transmission that drives brain function ultimately relies on the organization of neuronal circuits, understanding brain function requires an understanding of the principles that determine hierarchical neuronal structure in living or intact organisms. Recent advances in fluorescence imaging now enable quantitative characterization of neuronal structure across length scales, ranging from single-molecule localization using super-resolution imaging to whole-brain imaging using light-sheet microscopy on cleared samples. These tools, together with correlative electron microscopy and magnetic resonance imaging at the nanoscopic and macroscopic scales, respectively, now facilitate our ability to probe brain structure across its full range of length scales with cellular and molecular specificity. As these imaging datasets become increasingly accessible to researchers, novel statistical and computational frameworks will play an increasing role in efforts to relate hierarchical brain structure to its function. In this perspective, we discuss several prominent experimental advances that are ushering in a new era of quantitative fluorescence-based imaging in neuroscience along with novel computational and statistical strategies that are helping to distil our understanding of complex brain structure.
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Affiliation(s)
- L J Hogstrom
- Department of Biological Engineering , Massachusetts Institute of Technology , 77 Massachusetts Avenue, Building 16, Room 255, Cambridge, MA 02139 , USA
| | - S M Guo
- Department of Biological Engineering , Massachusetts Institute of Technology , 77 Massachusetts Avenue, Building 16, Room 255, Cambridge, MA 02139 , USA
| | - K Murugadoss
- Department of Biological Engineering , Massachusetts Institute of Technology , 77 Massachusetts Avenue, Building 16, Room 255, Cambridge, MA 02139 , USA
| | - M Bathe
- Department of Biological Engineering , Massachusetts Institute of Technology , 77 Massachusetts Avenue, Building 16, Room 255, Cambridge, MA 02139 , USA
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72
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Harb K, Magrinelli E, Nicolas CS, Lukianets N, Frangeul L, Pietri M, Sun T, Sandoz G, Grammont F, Jabaudon D, Studer M, Alfano C. Area-specific development of distinct projection neuron subclasses is regulated by postnatal epigenetic modifications. eLife 2016; 5:e09531. [PMID: 26814051 PMCID: PMC4744182 DOI: 10.7554/elife.09531] [Citation(s) in RCA: 69] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2015] [Accepted: 12/13/2015] [Indexed: 12/25/2022] Open
Abstract
During cortical development, the identity of major classes of long-distance projection neurons is established by the expression of molecular determinants, which become gradually restricted and mutually exclusive. However, the mechanisms by which projection neurons acquire their final properties during postnatal stages are still poorly understood. In this study, we show that the number of neurons co-expressing Ctip2 and Satb2, respectively involved in the early specification of subcerebral and callosal projection neurons, progressively increases after birth in the somatosensory cortex. Ctip2/Satb2 postnatal co-localization defines two distinct neuronal subclasses projecting either to the contralateral cortex or to the brainstem suggesting that Ctip2/Satb2 co-expression may refine their properties rather than determine their identity. Gain- and loss-of-function approaches reveal that the transcriptional adaptor Lmo4 drives this maturation program through modulation of epigenetic mechanisms in a time- and area-specific manner, thereby indicating that a previously unknown genetic program postnatally promotes the acquisition of final subtype-specific features.
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Affiliation(s)
- Kawssar Harb
- Institut de Biologie Valrose, University of Nice Sophia Antipolis, Nice, France.,Institut de Biologie Valrose, Institut national de la santé et de la recherche médicale, Nice, France.,Centre national de la recherche scientifique, Institut de Biologie Valrose, Nice, France
| | - Elia Magrinelli
- Institut de Biologie Valrose, University of Nice Sophia Antipolis, Nice, France.,Institut de Biologie Valrose, Institut national de la santé et de la recherche médicale, Nice, France.,Centre national de la recherche scientifique, Institut de Biologie Valrose, Nice, France
| | - Céline S Nicolas
- Institut de Biologie Valrose, University of Nice Sophia Antipolis, Nice, France.,Institut de Biologie Valrose, Institut national de la santé et de la recherche médicale, Nice, France.,Centre national de la recherche scientifique, Institut de Biologie Valrose, Nice, France
| | - Nikita Lukianets
- Institut de Biologie Valrose, University of Nice Sophia Antipolis, Nice, France.,Institut de Biologie Valrose, Institut national de la santé et de la recherche médicale, Nice, France.,Centre national de la recherche scientifique, Institut de Biologie Valrose, Nice, France
| | - Laura Frangeul
- Department of Basic Neurosciences, University of Geneva, Geneva, Switzerland
| | - Mariel Pietri
- Institut de Biologie Valrose, University of Nice Sophia Antipolis, Nice, France.,Institut de Biologie Valrose, Institut national de la santé et de la recherche médicale, Nice, France.,Centre national de la recherche scientifique, Institut de Biologie Valrose, Nice, France
| | - Tao Sun
- Department of Cell and Developmental Biology, Weill Medical College of Cornell University, New York, United States
| | - Guillaume Sandoz
- Institut de Biologie Valrose, University of Nice Sophia Antipolis, Nice, France.,Institut de Biologie Valrose, Institut national de la santé et de la recherche médicale, Nice, France.,Centre national de la recherche scientifique, Institut de Biologie Valrose, Nice, France
| | - Franck Grammont
- Institut de Biologie Valrose, University of Nice Sophia Antipolis, Nice, France.,Laboratoire J.A. Dieudonné, Nice, France
| | - Denis Jabaudon
- Department of Basic Neurosciences, University of Geneva, Geneva, Switzerland
| | - Michele Studer
- Institut de Biologie Valrose, University of Nice Sophia Antipolis, Nice, France.,Institut de Biologie Valrose, Institut national de la santé et de la recherche médicale, Nice, France.,Centre national de la recherche scientifique, Institut de Biologie Valrose, Nice, France
| | - Christian Alfano
- Institut de Biologie Valrose, University of Nice Sophia Antipolis, Nice, France.,Institut de Biologie Valrose, Institut national de la santé et de la recherche médicale, Nice, France.,Centre national de la recherche scientifique, Institut de Biologie Valrose, Nice, France
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73
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Cholera Toxin B Subunit Shows Transneuronal Tracing after Injection in an Injured Sciatic Nerve. PLoS One 2015; 10:e0144030. [PMID: 26640949 PMCID: PMC4671609 DOI: 10.1371/journal.pone.0144030] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2015] [Accepted: 11/12/2015] [Indexed: 11/25/2022] Open
Abstract
Cholera toxin B subunit (CTB) has been extensively used in the past for monosynaptic mapping. For decades, it was thought to lack the ability of transneuronal tracing. In order to investigate whether biotin conjugates of CTB (b-CTB) would pass through transneurons in the rat spinal cord, it was injected into the crushed left sciatic nerve. For experimental control, the first order afferent neuronal projections were defined by retrograde transport of fluorogold (FG, a non-transneuronal labeling marker as an experimental control) injected into the crushed right sciatic nerve in the same rat. Neurons containing b-CTB or FG were observed in the dorsal root ganglia (DRG) at the L4-L6 levels ipsilateral to the tracer injection. In the spinal cord, b-CTB labeled neurons were distributed in all laminae ipsilaterally between C7 and S1 segments, but labeling of neurons at the cervical segment was abolished when the T10 segment was transected completely. The interneurons, distributed in the intermediate gray matter and identified as gamma-aminobutyric acid-ergic (GABAergic), were labeled by b-CTB. In contrast, FG labeling was confined to the ventral horn neurons at L4-L6 spinal segments ipsilateral to the injection. b-CTB immunoreactivity remained to be restricted to the soma of neurons and often appeared as irregular patches detected by light and electron microscopy. Detection of monosialoganglioside (GM1) in b-CTB labeled neurons suggests that GM1 ganglioside may specifically enhance the uptake and transneuronal passage of b-CTB, thus supporting the notion that it may be used as a novel transneuronal tracer.
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74
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Maejima Y, Kumamoto K, Takenoshita S, Shimomura K. Projections from a single NUCB2/nesfatin-1 neuron in the paraventricular nucleus to different brain regions involved in feeding. Brain Struct Funct 2015; 221:4723-4731. [DOI: 10.1007/s00429-015-1150-4] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2015] [Accepted: 11/19/2015] [Indexed: 12/01/2022]
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75
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Albrecht O, Klug A. Laser-guided Neuronal Tracing In Brain Explants. J Vis Exp 2015:53333. [PMID: 26649948 PMCID: PMC4692760 DOI: 10.3791/53333] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
We present a technique which combines an in vitro tracer injection protocol, which uses a series of electrical and pressure pulses to increase dye uptake through electroporation in brain explants with targeted laser illumination and matching filter goggles during the procedure. The described technique of in vitro electroporation by itself yields relatively good visual control for targetting certain areas of the brain. By combining it with laser excitation of fluorescent genetic markers and their read-out through band-passing filter goggles, which can pick up the emissions of the genetically labeled cells/nuclei and the fluorescent tracing dye, a researcher can substantially increase the accuracy of injections by finding the area of interest and controlling for the dye-spread/uptake in the injection area much more efficiently. In addition, the laser illumination technique allows to study the functionality of a given neurocircuit by providing information about the type of neurons projecting to a certain area in cases where the GFP expression is linked to the type of transmitter expressed by a subpopulation of neurons.
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Affiliation(s)
- Otto Albrecht
- Department of Physiology and Biophysics, University of Colorado School of Medicine;
| | - Achim Klug
- Department of Physiology and Biophysics, University of Colorado School of Medicine
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76
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Zhou N, Hao Z, Zhao X, Maharjan S, Zhu S, Song Y, Yang B, Lu L. A novel fluorescent retrograde neural tracer: cholera toxin B conjugated carbon dots. NANOSCALE 2015; 7:15635-42. [PMID: 26285001 DOI: 10.1039/c5nr04361a] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
The retrograde neuroanatomical tracing method is a key technique to study the complex interconnections of the nervous system. Traditional tracers have several drawbacks, including time-consuming immunohistochemical or immunofluorescent staining procedures, rapid fluorescence quenching and low fluorescence intensity. Carbon dots (CDs) have been widely used as a fluorescent bio-probe due to their ultrasmall size, excellent optical properties, chemical stability, biocompatibility and low toxicity. Herein, we develop a novel fluorescent neural tracer: cholera toxin B-carbon dot conjugates (CTB-CDs). It can be taken up and retrogradely transported by neurons in the peripheral nervous system of rats. Our results show that CTB-CDs possess high photoluminescence intensity, good optical stability, a long shelf-life and non-toxicity. Tracing with CTB-CDs is a direct and more economical way of performing retrograde labelling experiments. Therefore, CTB-CDs are reliable fluorescent retrograde tracers.
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Affiliation(s)
- Nan Zhou
- Department of Hand Surgery, Jilin Provincial Key Laboratory of Tissue Repair, Reconstruction and Regeneration, First Hospital of Jilin University, Changchun 130021, China.
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McCall JG, Al-Hasani R, Siuda ER, Hong DY, Norris AJ, Ford CP, Bruchas MR. CRH Engagement of the Locus Coeruleus Noradrenergic System Mediates Stress-Induced Anxiety. Neuron 2015; 87:605-20. [PMID: 26212712 PMCID: PMC4529361 DOI: 10.1016/j.neuron.2015.07.002] [Citation(s) in RCA: 392] [Impact Index Per Article: 43.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2015] [Revised: 06/09/2015] [Accepted: 07/01/2015] [Indexed: 01/09/2023]
Abstract
The locus coeruleus noradrenergic (LC-NE) system is one of the first systems engaged following a stressful event. While numerous groups have demonstrated that LC-NE neurons are activated by many different stressors, the underlying neural circuitry and the role of this activity in generating stress-induced anxiety has not been elucidated. Using a combination of in vivo chemogenetics, optogenetics, and retrograde tracing, we determine that increased tonic activity of the LC-NE system is necessary and sufficient for stress-induced anxiety and aversion. Selective inhibition of LC-NE neurons during stress prevents subsequent anxiety-like behavior. Exogenously increasing tonic, but not phasic, activity of LC-NE neurons is alone sufficient for anxiety-like and aversive behavior. Furthermore, endogenous corticotropin-releasing hormone(+) (CRH(+)) LC inputs from the amygdala increase tonic LC activity, inducing anxiety-like behaviors. These studies position the LC-NE system as a critical mediator of acute stress-induced anxiety and offer a potential intervention for preventing stress-related affective disorders.
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Affiliation(s)
- Jordan G McCall
- Division of Basic Research, Department of Anesthesiology, Washington University School of Medicine, St. Louis, MO 63110, USA; Washington University Pain Center, Washington University School of Medicine, St. Louis, MO 63110, USA; Department of Anatomy and Neurobiology, Washington University School of Medicine, St. Louis, MO 63110, USA; Division of Biology and Biomedical Sciences, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Ream Al-Hasani
- Division of Basic Research, Department of Anesthesiology, Washington University School of Medicine, St. Louis, MO 63110, USA; Washington University Pain Center, Washington University School of Medicine, St. Louis, MO 63110, USA; Department of Anatomy and Neurobiology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Edward R Siuda
- Division of Basic Research, Department of Anesthesiology, Washington University School of Medicine, St. Louis, MO 63110, USA; Washington University Pain Center, Washington University School of Medicine, St. Louis, MO 63110, USA; Department of Anatomy and Neurobiology, Washington University School of Medicine, St. Louis, MO 63110, USA; Division of Biology and Biomedical Sciences, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Daniel Y Hong
- Division of Basic Research, Department of Anesthesiology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Aaron J Norris
- Division of Basic Research, Department of Anesthesiology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Christopher P Ford
- Department of Physiology and Biophysics, Department of Neurosciences, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA
| | - Michael R Bruchas
- Division of Basic Research, Department of Anesthesiology, Washington University School of Medicine, St. Louis, MO 63110, USA; Washington University Pain Center, Washington University School of Medicine, St. Louis, MO 63110, USA; Department of Anatomy and Neurobiology, Washington University School of Medicine, St. Louis, MO 63110, USA; Division of Biology and Biomedical Sciences, Washington University School of Medicine, St. Louis, MO 63110, USA.
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78
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The expression of calcitonin gene-related peptide on the neurons associated Zusanli (ST 36) in rats. Chin J Integr Med 2015. [PMID: 26224282 DOI: 10.1007/s11655-015-2111-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
OBJECTIVE To investigate the biochemical characteristic of the neurons associated Zusanli (ST 36) in the rat by using Alexa Fluor 594 conjugated cholera toxin subunit B (AF594-CTB) neural tracing and calcitonin gene-related peptide (CGRP) fluorescent immunohistochemical techniques. METHODS Four male Sprague Dawley rats were injected with AF594-CTB into the corresponding area of the Zusanli in the human body. After 3 surviving days, the rat's spinal cord and dorsal root ganglia (DRGs) at lumbar segments were dissected following perfusion with 4% paraformaldehyde, cut into sections, and then stained with CGRPfluorescent immunohistochemical method. RESULTS AF594-CTB labeled sensory neurons were detected in the L3-L6 DRGs with high concentration in L4 DRG, and the labeled motor neurons located in the dorsolateral and intermediate regions of lamina IX from L3-L5 segments with high concentration at L4. Meanwhile, CGRPpositive neural labeling distributed symmetrically on both sides of DRGs, anterior and dorsal horns of spinal cord. In the AF594-CTB labeled neurons, 37% sensory neurons and 100% motor neurons expressed CGRPpositive. CONCLUSION These findings present the morphological evidence to demonstrate that the sensory and motor neurons associated Zusanli in the rat distributed with segmental and regional patterns, and contained CGRP-expression.
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Chen JL, Margolis DJ, Stankov A, Sumanovski LT, Schneider BL, Helmchen F. Pathway-specific reorganization of projection neurons in somatosensory cortex during learning. Nat Neurosci 2015; 18:1101-8. [DOI: 10.1038/nn.4046] [Citation(s) in RCA: 113] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2015] [Accepted: 05/27/2015] [Indexed: 12/19/2022]
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Human Embryonic Stem Cell-Derived Progenitors Assist Functional Sensory Axon Regeneration after Dorsal Root Avulsion Injury. Sci Rep 2015; 5:10666. [PMID: 26053681 PMCID: PMC4459081 DOI: 10.1038/srep10666] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2015] [Accepted: 04/24/2015] [Indexed: 12/29/2022] Open
Abstract
Dorsal root avulsion results in permanent impairment of sensory functions due to disconnection between the peripheral and central nervous system. Improved strategies are therefore needed to reconnect injured sensory neurons with their spinal cord targets in order to achieve functional repair after brachial and lumbosacral plexus avulsion injuries. Here, we show that sensory functions can be restored in the adult mouse if avulsed sensory fibers are bridged with the spinal cord by human neural progenitor (hNP) transplants. Responses to peripheral mechanical sensory stimulation were significantly improved in transplanted animals. Transganglionic tracing showed host sensory axons only in the spinal cord dorsal horn of treated animals. Immunohistochemical analysis confirmed that sensory fibers had grown through the bridge and showed robust survival and differentiation of the transplants. Section of the repaired dorsal roots distal to the transplant completely abolished the behavioral improvement. This demonstrates that hNP transplants promote recovery of sensorimotor functions after dorsal root avulsion, and that these effects are mediated by spinal ingrowth of host sensory axons. These results provide a rationale for the development of novel stem cell-based strategies for functionally useful bridging of the peripheral and central nervous system.
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81
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Nakayama D, Baraki Z, Onoue K, Ikegaya Y, Matsuki N, Nomura H. Frontal association cortex is engaged in stimulus integration during associative learning. Curr Biol 2014; 25:117-23. [PMID: 25496961 DOI: 10.1016/j.cub.2014.10.078] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2014] [Revised: 10/13/2014] [Accepted: 10/31/2014] [Indexed: 11/28/2022]
Abstract
The frontal association cortex (FrA) is implicated in higher brain function. Aberrant FrA activity is likely to be involved in dementia pathology. However, the functional circuits both within the FrA and with other regions are unclear. A recent study showed that inactivation of the FrA impairs memory consolidation of an auditory fear conditioning in young mice. In addition, dendritic spine remodeling of FrA neurons is sensitive to paired sensory stimuli that produce associative memory. These findings suggest that the FrA is engaged in neural processes critical to associative learning. Here we characterize stimulus integration in the mouse FrA during associative learning. We experimentally separated contextual fear conditioning into context exposure and shock, and found that memory formation requires protein synthesis associated with both context exposure and shock in the FrA. Both context exposure and shock trigger Arc, an activity-dependent immediate-early gene, expression in the FrA, and a subset of FrA neurons was dually activated by both stimuli. In addition, we found that the FrA receives projections from the perirhinal (PRh) and insular (IC) cortices and basolateral amygdala (BLA), which are implicated in context and shock encoding. PRh and IC neurons projecting to the FrA were activated by context exposure and shock, respectively. Arc expression in the FrA associated with context exposure and shock depended on PRh activity and both IC and BLA activities, respectively. These findings indicate that the FrA is engaged in stimulus integration and contributes to memory formation in associative learning.
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Affiliation(s)
- Daisuke Nakayama
- Laboratory of Chemical Pharmacology, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Tokyo 113-0033, Japan
| | - Zohal Baraki
- Laboratory of Chemical Pharmacology, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Tokyo 113-0033, Japan
| | - Kousuke Onoue
- Laboratory of Chemical Pharmacology, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Tokyo 113-0033, Japan
| | - Yuji Ikegaya
- Laboratory of Chemical Pharmacology, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Tokyo 113-0033, Japan; Center for Information and Neural Networks, Suita City, Osaka 565-0871, Japan
| | - Norio Matsuki
- Laboratory of Chemical Pharmacology, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Tokyo 113-0033, Japan
| | - Hiroshi Nomura
- Laboratory of Chemical Pharmacology, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Tokyo 113-0033, Japan.
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82
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Abstract
The piriform cortex (PCX) is the largest component of the olfactory cortex and is hypothesized to be the locus of odor object formation. The distributed odorant representation found in PCX contrasts sharply with the topographical representation seen in other primary sensory cortices, making it difficult to test this view. Recent work in PCX has focused on functional characteristics of these distributed afferent and association fiber systems. However, information regarding the efferent projections of PCX and how those may be involved in odor representation and object recognition has been largely ignored. To investigate this aspect of PCX, we have used the efferent pathway from mouse PCX to the orbitofrontal cortex (OFC). Using double fluorescent retrograde tracing, we identified the output neurons (OPNs) of the PCX that project to two subdivisions of the OFC, the agranular insula and the lateral orbitofrontal cortex (AI-OPNs and LO-OPNs, respectively). We found that both AI-OPNs and LO-OPNs showed a distinct spatial topography within the PCX and fewer than 10% projected to both the AI and the LO as judged by double-labeling. These data revealed that the efferent component of the PCX may be topographically organized. Further, these data suggest a model for functional organization of the PCX in which the OPNs are grouped into parallel output circuits that provide olfactory information to different higher centers. The distributed afferent input from the olfactory bulb and the local PCX association circuits would then ensure a complete olfactory representation, pattern recognition capability, and neuroplasticity in each efferent circuit.
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83
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Albrecht O, Dondzillo A, Mayer F, Thompson JA, Klug A. Inhibitory projections from the ventral nucleus of the trapezoid body to the medial nucleus of the trapezoid body in the mouse. Front Neural Circuits 2014; 8:83. [PMID: 25120436 PMCID: PMC4114201 DOI: 10.3389/fncir.2014.00083] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2014] [Accepted: 06/30/2014] [Indexed: 01/17/2023] Open
Abstract
Neurons in the medial nucleus of the trapezoid body (MNTB) receive prominent excitatory input through the calyx of Held, a giant synapse that produces large and fast excitatory currents. MNTB neurons also receive inhibitory glycinergic inputs that are also large and fast, and match the calyceal excitation in terms of synaptic strength. GABAergic inputs provide additional inhibition to MNTB neurons. Inhibitory inputs to MNTB modify spiking of MNTB neurons both in-vitro and in-vivo, underscoring their importance. Surprisingly, the origin of the inhibitory inputs to MNTB has not been shown conclusively. We performed retrograde tracing, anterograde tracing, immunohistochemical experiments, and electrophysiological recordings to address this question. The results support the ventral nucleus of the trapezoid body (VNTB) as at least one major source of glycinergic input to MNTB. VNTB fibers enter the ipsilateral MNTB, travel along MNTB principal neurons and produce several bouton-like presynaptic terminals. Further, the contribution of GABA to the total inhibition declines during development, resulting in only a very minor fraction of GABAergic inhibition in adulthood, which is matched in time by a reduction in expression of a GABA synthetic enzyme in VNTB principal neurons.
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Affiliation(s)
- Otto Albrecht
- Department of Physiology and Biophysics, School of Medicine, University of ColoradoAurora, CO, USA
| | - Anna Dondzillo
- Department of Physiology and Biophysics, School of Medicine, University of ColoradoAurora, CO, USA
| | - Florian Mayer
- Department of Physiology and Biophysics, School of Medicine, University of ColoradoAurora, CO, USA
| | - John A. Thompson
- Department of Neurosurgery, School of Medicine, University of ColoradoAurora, CO, USA
| | - Achim Klug
- Department of Physiology and Biophysics, School of Medicine, University of ColoradoAurora, CO, USA
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84
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Neurogenesis and vascularization of the damaged brain using a lactate-releasing biomimetic scaffold. Biomaterials 2014; 35:4769-81. [PMID: 24636215 DOI: 10.1016/j.biomaterials.2014.02.051] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2014] [Accepted: 02/22/2014] [Indexed: 12/23/2022]
Abstract
Regenerative medicine strategies to promote recovery following traumatic brain injuries are currently focused on the use of biomaterials as delivery systems for cells or bioactive molecules. This study shows that cell-free biomimetic scaffolds consisting of radially aligned electrospun poly-l/dl lactic acid (PLA70/30) nanofibers release L-lactate and reproduce the 3D organization and supportive function of radial glia embryonic neural stem cells. The topology of PLA nanofibers supports neuronal migration while L-lactate released during PLA degradation acts as an alternative fuel for neurons and is required for progenitor maintenance. Radial scaffolds implanted into cavities made in the postnatal mouse brain fostered complete implant vascularization, sustained neurogenesis, and allowed the long-term survival and integration of the newly generated neurons. Our results suggest that the endogenous central nervous system is capable of regeneration through the in vivo dedifferentiation induced by biophysical and metabolic cues, with no need for exogenous cells, growth factors, or genetic manipulation.
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85
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Takemoto M, Hasegawa K, Nishimura M, Song WJ. The insular auditory field receives input from the lemniscal subdivision of the auditory thalamus in mice. J Comp Neurol 2014; 522:1373-89. [DOI: 10.1002/cne.23491] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2013] [Revised: 09/30/2013] [Accepted: 10/07/2013] [Indexed: 12/19/2022]
Affiliation(s)
- Makoto Takemoto
- Department of Sensory and Cognitive Physiology; Graduate School of Medical Sciences; Kumamoto University; umamoto 860-8556 Japan
| | - Kayoko Hasegawa
- Department of Sensory and Cognitive Physiology; Graduate School of Medical Sciences; Kumamoto University; umamoto 860-8556 Japan
| | - Masataka Nishimura
- Department of Sensory and Cognitive Physiology; Graduate School of Medical Sciences; Kumamoto University; umamoto 860-8556 Japan
| | - Wen-Jie Song
- Department of Sensory and Cognitive Physiology; Graduate School of Medical Sciences; Kumamoto University; umamoto 860-8556 Japan
- Program for Leading Graduate Schools; Health Life Science: Interdisciplinary and Globally Oriented (HIGO) Program, Kumamoto University; Kumamoto 860-8556 Japan
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86
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Yamashita T, Pala A, Pedrido L, Kremer Y, Welker E, Petersen CCH. Membrane potential dynamics of neocortical projection neurons driving target-specific signals. Neuron 2014; 80:1477-90. [PMID: 24360548 DOI: 10.1016/j.neuron.2013.10.059] [Citation(s) in RCA: 120] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/23/2013] [Indexed: 11/19/2022]
Abstract
Primary sensory cortex discriminates incoming sensory information and generates multiple processing streams toward other cortical areas. However, the underlying cellular mechanisms remain unknown. Here, by making whole-cell recordings in primary somatosensory barrel cortex (S1) of behaving mice, we show that S1 neurons projecting to primary motor cortex (M1) and those projecting to secondary somatosensory cortex (S2) have distinct intrinsic membrane properties and exhibit markedly different membrane potential dynamics during behavior. Passive tactile stimulation evoked faster and larger postsynaptic potentials (PSPs) in M1-projecting neurons, rapidly driving phasic action potential firing, well-suited for stimulus detection. Repetitive active touch evoked strongly depressing PSPs and only transient firing in M1-projecting neurons. In contrast, PSP summation allowed S2-projecting neurons to robustly signal sensory information accumulated during repetitive touch, useful for encoding object features. Thus, target-specific transformation of sensory-evoked synaptic potentials by S1 projection neurons generates functionally distinct output signals for sensorimotor coordination and sensory perception.
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Affiliation(s)
- Takayuki Yamashita
- Laboratory of Sensory Processing, Brain Mind Institute, Faculty of Life Sciences, École Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland.
| | - Aurélie Pala
- Laboratory of Sensory Processing, Brain Mind Institute, Faculty of Life Sciences, École Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland
| | - Leticia Pedrido
- Department of Fundamental Neurosciences, University of Lausanne, 1005 Lausanne, Switzerland
| | - Yves Kremer
- Laboratory of Sensory Processing, Brain Mind Institute, Faculty of Life Sciences, École Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland
| | - Egbert Welker
- Department of Fundamental Neurosciences, University of Lausanne, 1005 Lausanne, Switzerland
| | - Carl C H Petersen
- Laboratory of Sensory Processing, Brain Mind Institute, Faculty of Life Sciences, École Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland.
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Specificity of Sensory and Motor Neurons Associated with BL40 and GB30 in the Rat: A Dual Fluorescent Labeling Study. EVIDENCE-BASED COMPLEMENTARY AND ALTERNATIVE MEDICINE 2013; 2013:643403. [PMID: 24027595 PMCID: PMC3763267 DOI: 10.1155/2013/643403] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/05/2013] [Accepted: 07/23/2013] [Indexed: 12/04/2022]
Abstract
The purpose of this study is to investigate the specific innervations on “Weizhong” (BL40) and “Huantiao” (GB30) by using a dual neural tracing technique. After Alexa Fluor 488 and 594 conjugates of cholera toxin subunit B (AF488/594-CTB) were, respectively, injected into BL40 and GB30 in the same rat, the labeled sensory and motor neurons were examined in the rat's dorsal root ganglia (DRGs) and spinal cord at thoracic (T) and lumbar (L) segments with a laser scanning confocal microscope. In the cases of BL40 injection, AF488-CTB labeled sensory and motor neurons were located in L2–6 DRGs and on the mediolateral part of spinal ventral horn from L3 to L5 segments, respectively. By contrast, in the cases of GB30 injection, AF594-CTB labeled sensory and motor neurons were distributed in T13-L6 DRGs and on the anterolateral part of spinal ventral horn from L1 to L5 segments, respectively. These results indicate that the sensory and motor neurons associated with BL40 and GB30 are located in different spinal segments and regions in the nervous system, providing the neuroanatomical evidence to serve the specificity of acupoints.
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88
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Takahashi Y, Zhang W, Sameshima K, Kuroki C, Matsumoto A, Sunanaga J, Kono Y, Sakurai T, Kanmura Y, Kuwaki T. Orexin neurons are indispensable for prostaglandin E2-induced fever and defence against environmental cooling in mice. J Physiol 2013; 591:5623-43. [PMID: 23959674 DOI: 10.1113/jphysiol.2013.261271] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
We recently showed using prepro-orexin knockout (ORX-KO) mice and orexin neuron-ablated (ORX-AB) mice that orexin neurons in the hypothalamus, but not orexin peptides per se, are indispensable for stress-induced thermogenesis. To examine whether orexin neurons are more generally involved in central thermoregulatory mechanisms, we applied other forms of thermogenic perturbations, including brain prostaglandin E2 (PGE2) injections which mimic inflammatory fever and environmental cold exposure, to ORX-KO mice, ORX-AB mice and their wild-type (WT) litter mates. ORX-AB mice, but not ORX-KO mice, exhibited a blunted PGE2-induced fever and intolerance to cold (5°C) exposure, and these findings were similar to the results previously obtained with stress-induced thermogenesis. PGE2-induced shivering was also attenuated in ORX-AB mice. Both mutants responded similarly to environmental heating (39°C). In WT and ORX-KO mice, the administration of PGE2 and cold exposure activated orexin neurons, as revealed by increased levels of expression of c-fos. Injection of retrograde tracer into the medullary raphe nucleus revealed direct and indirect projection from the orexin neurons, of which the latter seemed to be preserved in the ORX-AB mice. In addition, we found that glutamate receptor antagonists (D-(-)-2-amino-5-phosphonopentanoic acid and 6-cyano-7-nitroquinoxaline-2,3-dione) but not orexin receptor antagonists (SB334867 and OX2 29) successfully inhibited PGE2-induced fever in WT mice. These results suggest that orexin neurons are important in general thermogenic processes, and their importance is not restricted to stress-induced thermogenesis. In addition, these results indicate the possible involvement of glutamate in orexin neurons implicated in PGE2-induced fever.
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Affiliation(s)
- Yoshiko Takahashi
- T. Kuwaki: Department of Physiology, Kagoshima University Graduate School of Medical and Dental Sciences, Sakuragaoka 8-35-1, Kagoshima 890-8544, Japan.
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89
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Chen JL, Carta S, Soldado-Magraner J, Schneider BL, Helmchen F. Behaviour-dependent recruitment of long-range projection neurons in somatosensory cortex. Nature 2013; 499:336-40. [DOI: 10.1038/nature12236] [Citation(s) in RCA: 250] [Impact Index Per Article: 22.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2012] [Accepted: 04/30/2013] [Indexed: 12/18/2022]
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90
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Wasserman DI, Wang HG, Rashid AJ, Josselyn SA, Yeomans JS. Cholinergic control of morphine-induced locomotion in rostromedial tegmental nucleus versus ventral tegmental area sites. Eur J Neurosci 2013; 38:2774-85. [DOI: 10.1111/ejn.12279] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2013] [Revised: 05/12/2013] [Accepted: 05/14/2013] [Indexed: 01/01/2023]
Affiliation(s)
- David I. Wasserman
- Department of Psychology; University of Toronto; 100 St. George Street; Toronto; ON; M5S 3G3; Canada
| | - Haoran G. Wang
- Department of Psychology; University of Toronto; 100 St. George Street; Toronto; ON; M5S 3G3; Canada
| | - Asim J. Rashid
- Sick Children's Research Institute; University of Toronto; 555 University Avenue; Toronto; ON; M5G 1X8; Canada
| | - Sheena A. Josselyn
- Sick Children's Research Institute; University of Toronto; 555 University Avenue; Toronto; ON; M5G 1X8; Canada
| | - John S. Yeomans
- Department of Psychology; University of Toronto; 100 St. George Street; Toronto; ON; M5S 3G3; Canada
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91
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Osten P, Margrie TW. Mapping brain circuitry with a light microscope. Nat Methods 2013; 10:515-23. [PMID: 23722211 PMCID: PMC3982327 DOI: 10.1038/nmeth.2477] [Citation(s) in RCA: 159] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2013] [Accepted: 04/15/2013] [Indexed: 12/16/2022]
Abstract
The beginning of the 21st century has seen a renaissance in light microscopy and anatomical tract tracing that together are rapidly advancing our understanding of the form and function of neuronal circuits. The introduction of instruments for automated imaging of whole mouse brains, new cell type–specific and trans-synaptic tracers, and computational methods for handling the whole-brain data sets has opened the door to neuroanatomical studies at an unprecedented scale. We present an overview of the present state and future opportunities in charting long-range and local connectivity in the entire mouse brain and in linking brain circuits to function.
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Affiliation(s)
- Pavel Osten
- Cold Spring Harbor Laboratory, Cold Spring Harbor, New York, USA.
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92
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Identification of functional circuitry between retrosplenial and postrhinal cortices during fear conditioning. J Neurosci 2012; 32:12076-86. [PMID: 22933791 DOI: 10.1523/jneurosci.2814-12.2012] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
The retrosplenial cortex (RSP) and postrhinal cortex (POR) are heavily interconnected with medial temporal lobe structures involved in learning and memory. Previous studies indicate that RSP and POR are necessary for contextual fear conditioning, but it remains unclear whether these regions contribute individually or instead work together as a functional circuit to modulate learning and/or memory. In Experiment 1, learning-related neuronal activity was assessed in RSP from home cage, shock-only, context-only, or fear-conditioned rats using real-time PCR and immunohistochemical methods to quantify immediate-early gene expression. A significant increase in activity-regulated cytoskeleton-associated protein (Arc) mRNA and Arc and c-Fos protein expression was detected in RSP from fear-conditioned rats compared with all other groups. In Experiment 2, retrograde tracing combined with immunohistochemistry revealed that, compared with controls, a significant proportion of cells projecting from RSP to POR were immunopositive for c-Fos in fear-conditioned rats. These results demonstrate that neurons projecting from RSP to POR are indeed active during fear conditioning. In Experiment 3, a functional disconnection paradigm was used to further examine the interaction between RSP and POR during fear conditioning. Compared with controls, rats with unilateral lesions of RSP and POR on opposite sides of the brain exhibited impaired contextual fear memory, whereas rats with unilateral lesions in the same hemisphere displayed intermediate levels of freezing compared with controls and rats with contralateral lesions. Collectively, these results are the first to show that RSP and POR function as a cortical network necessary for contextual fear learning and memory.
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93
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Abstract
The examination of tissue histology by light microscopy is a fundamental tool for investigating the structure and function of organs under normal and disease states. Many current techniques for tissue sectioning, imaging and analysis are time-consuming, and they present major limitations for 3D tissue reconstruction. The introduction of methods to achieve the optical clearing and subsequent light-sheet laser scanning of entire transparent organs without sectioning represents a major advance in the field. We recently developed a highly reproducible and versatile clearing procedure called 3D imaging of solvent-cleared organs, or 3DISCO, which is applicable to diverse tissues including brain, spinal cord, immune organs and tumors. Here we describe a detailed protocol for performing 3DISCO and present its application to various microscopy techniques, including example results from various mouse tissues. The tissue clearing takes as little as 3 h, and imaging can be completed in ∼45 min. 3DISCO is a powerful technique that offers 3D histological views of tissues in a fraction of the time and labor required to complete standard histology studies.
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94
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Mamedov I, Engelmann J, Eschenko O, Beyerlein M, Logothetis NK. Dual-functional probes towards in vivo studies of brain connectivity and plasticity. Chem Commun (Camb) 2012; 48:2755-7. [DOI: 10.1039/c1cc15991g] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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95
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A half century of experimental neuroanatomical tracing. J Chem Neuroanat 2011; 42:157-83. [PMID: 21782932 DOI: 10.1016/j.jchemneu.2011.07.001] [Citation(s) in RCA: 149] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2011] [Revised: 07/04/2011] [Accepted: 07/04/2011] [Indexed: 01/05/2023]
Abstract
Most of our current understanding of brain function and dysfunction has its firm base in what is so elegantly called the 'anatomical substrate', i.e. the anatomical, histological, and histochemical domains within the large knowledge envelope called 'neuroscience' that further includes physiological, pharmacological, neurochemical, behavioral, genetical and clinical domains. This review focuses mainly on the anatomical domain in neuroscience. To a large degree neuroanatomical tract-tracing methods have paved the way in this domain. Over the past few decades, a great number of neuroanatomical tracers have been added to the technical arsenal to fulfill almost any experimental demand. Despite this sophisticated arsenal, the decision which tracer is best suited for a given tracing experiment still represents a difficult choice. Although this review is obviously not intended to provide the last word in the tract-tracing field, we provide a survey of the available tracing methods including some of their roots. We further summarize our experience with neuroanatomical tracers, in an attempt to provide the novice user with some advice to help this person to select the most appropriate criteria to choose a tracer that best applies to a given experimental design.
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96
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Wu CWH, Vasalatiy O, Liu N, Wu H, Cheal S, Chen DY, Koretsky AP, Griffiths GL, Tootell RBH, Ungerleider LG. Development of a MR-visible compound for tracing neuroanatomical connections in vivo. Neuron 2011; 70:229-43. [PMID: 21521610 PMCID: PMC3419536 DOI: 10.1016/j.neuron.2011.03.010] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/16/2011] [Indexed: 10/18/2022]
Abstract
Traditional studies of neuroanatomical connections require injection of tracer compounds into living brains, then histology of the postmortem tissue. Here, we describe and validate a compound that reveals neuronal connections in vivo, using MRI. The classic anatomical tracer CTB (cholera-toxin subunit-B) was conjugated with a gadolinium-chelate to form GdDOTA-CTB. GdDOTA-CTB was injected into the primary somatosensory cortex (S1) or the olfactory pathway of rats. High-resolution MR images were collected at a range of time points at 11.7T and 7T. The transported GdDOTA-CTB was visible for at least 1 month post-injection, clearing within 2 months. Control injections of non-conjugated GdDOTA into S1 were not transported and cleared within 1-2 days. Control injections of Gd-Albumin were not transported either, clearing within 7 days. These MR results were verified by classic immunohistochemical staining for CTB, in the same animals. The GdDOTA-CTB neuronal transport was target specific, monosynaptic, stable for several weeks, and reproducible.
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Affiliation(s)
- Carolyn W-H Wu
- Laboratory of Functional and Molecular Imaging, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20814, USA.
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97
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Abudureheman A, Nakagawa S. Retinopetal neurons located in the diencephalon of the Japanese monkey (Macaca fuscata). Okajimas Folia Anat Jpn 2010; 87:17-23. [PMID: 20715568 DOI: 10.2535/ofaj.87.17] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
After a monocular injection of the cholera toxin B subunit (CTB) into the vitreous chamber of one eye, the retrogradely labeled retinopetal neurons were studied in the diencephalon of the Japanese monkey. The retrogradely transported tracer was visualized using the peroxidase antibody technique and an anti-cholera toxin antibody. The CTB-labeled nerve cell bodies were scattered in the periventricular nucleus of the hypothalamus, lateral hypothalamic area, and midline nuclei of the thalamus on both sides. In addition, a few retrogradely labeled nerve somata were observed in the most rostral portion of the lateral geniculate nucleus on the contralateral side.
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Affiliation(s)
- Abuduaini Abudureheman
- Laboratory for Neuroanatomy, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima 890-8520, Japan
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98
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Davidson S, Truong H, Nakagawa Y, Giesler GJ. A microinjection technique for targeting regions of embryonic and neonatal mouse brain in vivo. Brain Res 2009; 1307:43-52. [PMID: 19840780 DOI: 10.1016/j.brainres.2009.10.024] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2009] [Revised: 10/05/2009] [Accepted: 10/11/2009] [Indexed: 01/30/2023]
Abstract
A simple pressure injection technique was developed to deliver substances into specific regions of the embryonic and neonatal mouse brain in vivo. The retrograde tracers Fluorogold and cholera toxin B subunit were used to test the validity of the technique. Injected animals survived the duration of transport (24-48 h) and then were sacrificed and perfused with fixative. Small injections (<or=50 nL) were contained within targeted structures of the perinatal brain and labeled distant cells of origin in several model neural pathways. Traced neural pathways in the perinatal mouse were further examined with immunohistochemical methods to test the feasibility of double labeling experiments during development. Several experimental situations in which this technique would be useful are discussed, for example, to label projection neurons in slice or culture preparations of mouse embryos and neonates. The administration of pharmacological or genetic vectors directly into specific neural targets during development should also be feasible. An examination of the form of neural pathways during early stages of life may lead to insights regarding the functional changes that occur during critical periods of development and provide an anatomic basis for some neurodevelopmental disorders.
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Affiliation(s)
- Steve Davidson
- Department of Neuroscience, University of Minnesota, Minneapolis, MN 55455, USA
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99
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The efficacy of the fluorescent conjugates of cholera toxin subunit B for multiple retrograde tract tracing in the central nervous system. Brain Struct Funct 2009; 213:367-73. [PMID: 19621243 DOI: 10.1007/s00429-009-0212-x] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2009] [Accepted: 07/07/2009] [Indexed: 10/20/2022]
Abstract
Cholera toxin subunit B (CTB) is a sensitive neuroanatomical tracer that generally transports retrogradely in the nervous system, and has been used extensively in brightfield microscopy. Recently, Alexa Fluor (AF) conjugates of CTB have been made available, which now allows multiple tracing with CTB. In this study, we examined the efficacy of these new AF-CTB conjugates when injected into the brain, and compared the results to our previous experiences using fluorescent 3k dextran amines. To test this, we injected AF 488 and AF 594 CTB into the anterior cingulate cortex and the medial agranular cortex in the rat, and examined the retrograde transport to the lateral posterior nucleus of the thalamus. We found that CTB was very viscous but yet very sensitive: small injection sites revealed very intense and detailed retrograde labeling. Anterograde transport was seen only when tissue at the injection site was damaged. These findings suggest that AF-CTB is a very reliable and sensitive retrograde tracer, and should be the first choice retrograde tracer for experiments examining multiple pathways within the same brain.
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