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Qiao X, Grieco SF, Yu Z, Holmes TC, Xu X. Intranasal Delivery of Ketamine Induces Cortical Disinhibition. eNeuro 2024; 11:ENEURO.0107-23.2023. [PMID: 38164560 PMCID: PMC10849039 DOI: 10.1523/eneuro.0107-23.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2023] [Revised: 11/02/2023] [Accepted: 11/21/2023] [Indexed: 01/03/2024] Open
Abstract
Our previous studies find that subcutaneously administered (s.c.) subanesthetic ketamine promotes sustained cortical disinhibition and plasticity in adult mouse binocular visual cortex (bV1). We hypothesized that intranasal delivery (i.n.) of subanesthetic ketamine may have similar actions. To test this, we delivered ketamine (10 mg/kg, i.n.) to adult mice and then recorded excitatory pyramidal neurons or PV+ interneurons in L2/3 of bV1 slices. In pyramidal neurons the baseline IPSC amplitudes from mice treated with ketamine are significantly weaker than those in control mice. Acute bath application of neuregulin-1 (NRG1) to cortical slices increases these IPSC amplitudes in mice treated with ketamine but not in controls. In PV+ interneurons, the baseline EPSC amplitudes from mice treated with ketamine are significantly weaker than those in control mice. Acute bath application of NRG1 to cortical slices increases these EPSC amplitudes in mice treated with ketamine but not in controls. We also found that mice treated with ketamine exhibit increased pCREB staining in L2/3 of bV1. Together, our results show that a single intranasal delivery of ketamine reduces PV+ interneuron excitation and reduces pyramidal neuron inhibition and that these effects are acutely reversed by NRG1. These results are significant as they show that intranasal delivery of ketamine induces cortical disinhibition, which has implications for the treatment of psychiatric, neurologic, and ophthalmic disorders.
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Affiliation(s)
- Xin Qiao
- Department of Anatomy and Neurobiology, School of Medicine, University of California, Irvine 92697, California
| | - Steven F Grieco
- Department of Anatomy and Neurobiology, School of Medicine, University of California, Irvine 92697, California
- Center for Neural Circuit Mapping, University of California, Irvine 92697, California
| | - Zhaoxia Yu
- Center for Neural Circuit Mapping, University of California, Irvine 92697, California
- Department of Statistics, Donald Bren School of Information and Computer Sciences, Irvine 92697, California
| | - Todd C Holmes
- Center for Neural Circuit Mapping, University of California, Irvine 92697, California
- Department of Physiology and Biophysics, School of Medicine, University of California, Irvine 92697, California
| | - Xiangmin Xu
- Department of Anatomy and Neurobiology, School of Medicine, University of California, Irvine 92697, California
- Center for Neural Circuit Mapping, University of California, Irvine 92697, California
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Navarro P, Oweiss K. Compressive sensing of functional connectivity maps from patterned optogenetic stimulation of neuronal ensembles. PATTERNS (NEW YORK, N.Y.) 2023; 4:100845. [PMID: 37876895 PMCID: PMC10591201 DOI: 10.1016/j.patter.2023.100845] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/26/2022] [Revised: 04/04/2023] [Accepted: 08/25/2023] [Indexed: 10/26/2023]
Abstract
Mapping functional connectivity between neurons is an essential step toward probing the neural computations mediating behavior. Accurately determining synaptic connectivity maps in populations of neurons is challenging in terms of yield, accuracy, and experimental time. Here, we developed a compressive sensing approach to reconstruct synaptic connectivity maps based on random two-photon cell-targeted optogenetic stimulation and membrane voltage readout of many putative postsynaptic neurons. Using a biophysical network model of interconnected populations of excitatory and inhibitory neurons, we characterized mapping recall and precision as a function of network observability, sparsity, number of neurons stimulated, off-target stimulation, synaptic reliability, propagation latency, and network topology. We found that mapping can be achieved with far fewer measurements than the standard pairwise sequential approach, with network sparsity and synaptic reliability serving as primary determinants of the performance. Our results suggest a rapid and efficient method to reconstruct functional connectivity of sparsely connected neuronal networks.
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Affiliation(s)
- Phillip Navarro
- Electrical and Computer Engineering Department, University of Florida, Gainesville, FL 32611, USA
| | - Karim Oweiss
- Electrical and Computer Engineering Department, University of Florida, Gainesville, FL 32611, USA
- Department of Biomedical Engineering, University of Florida, Gainesville, FL 32611, USA
- Department of Neurology, University of Florida, Gainesville, FL 32611, USA
- Department of Neuroscience, McKnight Brain Institute, University of Florida, Gainesville, FL 32611, USA
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Grieco SF, Qiao X, Johnston KG, Chen L, Nelson RR, Lai C, Holmes TC, Xu X. Neuregulin signaling mediates the acute and sustained antidepressant effects of subanesthetic ketamine. Transl Psychiatry 2021; 11:144. [PMID: 33627623 PMCID: PMC7904825 DOI: 10.1038/s41398-021-01255-4] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/17/2020] [Revised: 01/09/2021] [Accepted: 02/01/2021] [Indexed: 01/03/2023] Open
Abstract
Subanesthetic ketamine evokes rapid antidepressant effects in human patients that persist long past ketamine's chemical half-life of ~2 h. Ketamine's sustained antidepressant action may be due to modulation of cortical plasticity. We find that ketamine ameliorates depression-like behavior in the forced swim test in adult mice, and this depends on parvalbumin-expressing (PV) neuron-directed neuregulin-1 (NRG1)/ErbB4 signaling. Ketamine rapidly downregulates NRG1 expression in PV inhibitory neurons in mouse medial prefrontal cortex (mPFC) following a single low-dose ketamine treatment. This NRG1 downregulation in PV neurons co-tracks with the decreases in synaptic inhibition to mPFC excitatory neurons for up to a week. This results from reduced synaptic excitation to PV neurons, and is blocked by exogenous NRG1 as well as by PV targeted ErbB4 receptor knockout. Thus, we conceptualize that ketamine's effects are mediated through rapid and sustained cortical disinhibition via PV-specific NRG1 signaling. Our findings reveal a novel neural plasticity-based mechanism for ketamine's acute and long-lasting antidepressant effects.
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Affiliation(s)
- Steven F. Grieco
- grid.266093.80000 0001 0668 7243Department of Anatomy and Neurobiology, School of Medicine, University of California, Irvine, CA 92697-1275 USA
| | - Xin Qiao
- grid.266093.80000 0001 0668 7243Department of Anatomy and Neurobiology, School of Medicine, University of California, Irvine, CA 92697-1275 USA
| | - Kevin G. Johnston
- grid.266093.80000 0001 0668 7243Department of Mathematics, University of California, Irvine, CA 92697-3875 USA
| | - Lujia Chen
- grid.266093.80000 0001 0668 7243Department of Anatomy and Neurobiology, School of Medicine, University of California, Irvine, CA 92697-1275 USA
| | - Renetta R. Nelson
- grid.266093.80000 0001 0668 7243Department of Anatomy and Neurobiology, School of Medicine, University of California, Irvine, CA 92697-1275 USA
| | - Cary Lai
- grid.411377.70000 0001 0790 959XDepartment of Psychological and Brain Sciences, Indiana University, Bloomington, IN 47405-7000 USA
| | - Todd C. Holmes
- grid.19006.3e0000 0000 9632 6718Department of Physiology and Biophysics, School of Medicine, Universityof California, Irvine, CA 92697- 4560 USA ,grid.266093.80000 0001 0668 7243The Center for Neural Circuit Mapping, University of California, Irvine, CA 92697 USA
| | - Xiangmin Xu
- Department of Anatomy and Neurobiology, School of Medicine, University of California, Irvine, CA, 92697-1275, USA. .,The Center for Neural Circuit Mapping, University of California, Irvine, CA, 92697, USA. .,Department of Biomedical Engineering, University of California, Irvine, CA, 92697-2715, USA. .,Department of Microbiology and Molecular Genetics, University of California, Irvine, CA, 92697-4025, USA. .,Department of Computer Science, University of California, Irvine, CA, 92697-3435, USA.
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4
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Microglia Elimination Increases Neural Circuit Connectivity and Activity in Adult Mouse Cortex. J Neurosci 2020; 41:1274-1287. [PMID: 33380470 DOI: 10.1523/jneurosci.2140-20.2020] [Citation(s) in RCA: 70] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2020] [Revised: 11/16/2020] [Accepted: 12/13/2020] [Indexed: 12/21/2022] Open
Abstract
Microglia have crucial roles in sculpting synapses and maintaining neural circuits during development. To test the hypothesis that microglia continue to regulate neural circuit connectivity in adult brain, we have investigated the effects of chronic microglial depletion, via CSF1R inhibition, on synaptic connectivity in the visual cortex in adult mice of both sexes. We find that the absence of microglia dramatically increases both excitatory and inhibitory synaptic connections to excitatory cortical neurons assessed with functional circuit mapping experiments in acutely prepared adult brain slices. Microglia depletion leads to increased densities and intensities of perineuronal nets. Furthermore, in vivo calcium imaging across large populations of visual cortical neurons reveals enhanced neural activities of both excitatory neurons and parvalbumin-expressing interneurons in the visual cortex following microglia depletion. These changes recover following adult microglia repopulation. In summary, our new results demonstrate a prominent role of microglia in sculpting neuronal circuit connectivity and regulating subsequent functional activity in adult cortex.SIGNIFICANCE STATEMENT Microglia are the primary immune cell of the brain, but recent evidence supports that microglia play an important role in synaptic sculpting during development. However, it remains unknown whether and how microglia regulate synaptic connectivity in adult brain. Our present work shows chronic microglia depletion in adult visual cortex induces robust increases in perineuronal nets, and enhances local excitatory and inhibitory circuit connectivity to excitatory neurons. Microglia depletion increases in vivo neural activities of both excitatory neurons and parvalbumin inhibitory neurons. Our new results reveal new potential avenues to modulate adult neural plasticity by microglia manipulation to better treat brain disorders, such as Alzheimer's disease.
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Grieco SF, Qiao X, Zheng X, Liu Y, Chen L, Zhang H, Yu Z, Gavornik JP, Lai C, Gandhi SP, Holmes TC, Xu X. Subanesthetic Ketamine Reactivates Adult Cortical Plasticity to Restore Vision from Amblyopia. Curr Biol 2020; 30:3591-3603.e8. [PMID: 32822611 PMCID: PMC7925140 DOI: 10.1016/j.cub.2020.07.008] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2020] [Revised: 05/07/2020] [Accepted: 07/01/2020] [Indexed: 12/09/2022]
Abstract
Subanesthetic ketamine evokes rapid and long-lasting antidepressant effects in human patients. The mechanism for ketamine's effects remains elusive, but ketamine may broadly modulate brain plasticity processes. We show that single-dose ketamine reactivates adult mouse visual cortical plasticity and promotes functional recovery of visual acuity defects from amblyopia. Ketamine specifically induces downregulation of neuregulin-1 (NRG1) expression in parvalbumin-expressing (PV) inhibitory neurons in mouse visual cortex. NRG1 downregulation in PV neurons co-tracks both the fast onset and sustained decreases in synaptic inhibition to excitatory neurons, along with reduced synaptic excitation to PV neurons in vitro and in vivo following a single ketamine treatment. These effects are blocked by exogenous NRG1 as well as PV targeted receptor knockout. Thus, ketamine reactivation of adult visual cortical plasticity is mediated through rapid and sustained cortical disinhibition via downregulation of PV-specific NRG1 signaling. Our findings reveal the neural plasticity-based mechanism for ketamine-mediated functional recovery from adult amblyopia.
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Affiliation(s)
- Steven F Grieco
- Department of Anatomy and Neurobiology, School of Medicine, University of California, Irvine, CA 92697-1275, USA
| | - Xin Qiao
- Department of Anatomy and Neurobiology, School of Medicine, University of California, Irvine, CA 92697-1275, USA
| | - Xiaoting Zheng
- Department of Neurobiology and Behavior, School of Biology, University of California, Irvine, CA 92697-1275, USA
| | - Yongjun Liu
- Department of Anatomy and Neurobiology, School of Medicine, University of California, Irvine, CA 92697-1275, USA; Key Laboratory of Pollinating Insect Biology, Institute of Agricultural Research, Chinese Academy of Agricultural Sciences, Beijing 100093, China
| | - Lujia Chen
- Department of Anatomy and Neurobiology, School of Medicine, University of California, Irvine, CA 92697-1275, USA
| | - Hai Zhang
- Department of Anatomy and Neurobiology, School of Medicine, University of California, Irvine, CA 92697-1275, USA
| | - Zhaoxia Yu
- Department of Statistics, University of California, Irvine, CA 92697-1250, USA
| | | | - Cary Lai
- Department of Psychological and Brain Sciences, Indiana University, Bloomington, IN 47405-7000, USA
| | - Sunil P Gandhi
- Department of Neurobiology and Behavior, School of Biology, University of California, Irvine, CA 92697-1275, USA
| | - Todd C Holmes
- Department of Physiology and Biophysics, School of Medicine, University of California, Irvine, CA 92697- 4560, USA
| | - Xiangmin Xu
- Department of Anatomy and Neurobiology, School of Medicine, University of California, Irvine, CA 92697-1275, USA; Department of Biomedical Engineering, University of California, Irvine, CA 92697-2715, USA; Department of Microbiology and Molecular Genetics, University of California, Irvine, CA 92697-4025, USA.
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Functional Reorganization of Local Circuit Connectivity in Superficial Spinal Dorsal Horn with Neuropathic Pain States. eNeuro 2019; 6:ENEURO.0272-19.2019. [PMID: 31533959 PMCID: PMC6787342 DOI: 10.1523/eneuro.0272-19.2019] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2019] [Revised: 08/27/2019] [Accepted: 09/05/2019] [Indexed: 01/12/2023] Open
Abstract
The spinal dorsal horn is the first relay structure coding for pain transmission and modulation. Previous anatomical and electrophysiological studies have examined spinal dorsal horn circuit connections and network activity. Further work is required to understand spinal cord sensory information processing that underlies pathological neuropathic pain states. Our previous studies suggest that peripheral nerve injury enhances presynaptic excitatory input onto spinal superficial dorsal horn neurons, which in turn contributes to pathologic nociception. The potential changes in local postsynaptic circuits in the dorsal horn that lead to pathologically heightened behavioral responses to pain remain largely unexplored. We combined whole-cell electrophysiological recordings with laser-scanning photostimulation to test whether peripheral nerve injury in the spinal nerve ligation (SNL) mouse model of neuropathic pain leads to alterations in the functional connectivity of spinal cord circuits including lamina II excitatory interneurons. Here we show that SNL enhances excitation and decreases inhibition to lamina II excitatory interneurons along with their increased glutamate-evoked excitability. The enhanced excitatory postsynaptic input and connectivity evoked by SNL eventually return to normal levels concurrently with the resolution of the neuropathic pain states. The physiological pattern highly correlates with mouse pain behaviors following SNL, supporting a neurophysiological mechanism of central sensitization and neuropathic pain that is functionally localized to the spinal dorsal horn. Together, these data support that SNL induces functional changes in synaptic input and connectivity to lamina II excitatory interneurons that code for pain perception, and thus provide new insights into the mechanism and locus of pain hypersensitivity.
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7
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Rojas P, Plath JA, Gestrich J, Ananthasubramaniam B, Garcia ME, Herzel H, Stengl M. Beyond spikes: Multiscale computational analysis of in vivo long-term recordings in the cockroach circadian clock. Netw Neurosci 2019; 3:944-968. [PMID: 31637333 PMCID: PMC6777951 DOI: 10.1162/netn_a_00106] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2018] [Accepted: 07/27/2019] [Indexed: 11/28/2022] Open
Abstract
The circadian clock of the nocturnal Madeira cockroach is located in the accessory medulla, a small nonretinotopic neuropil in the brain's visual system. The clock comprises about 240 neurons that control rhythms in physiology and behavior such as sleep-wake cycles. The clock neurons contain an abundant number of partly colocalized neuropeptides, among them pigment-dispersing factor (PDF), the insects' most important circadian coupling signal that controls sleep-wake rhythms. We performed long-term loose-patch clamp recordings under 12:12-hr light-dark cycles in the cockroach clock in vivo. A wide range of timescales, from milliseconds to seconds, were found in spike and field potential patterns. We developed a framework of wavelet transform-based methods to detect these multiscale electrical events. We analyzed frequencies and patterns of events with interesting dynamic features, such as mixed-mode oscillations reminiscent of sharp-wave ripples. Oscillations in the beta/gamma frequency range (20-40 Hz) were observed to rise at dawn, when PDF is released, peaking just before the onset of locomotor activity of the nocturnal cockroach. We expect that in vivo electrophysiological recordings combined with neuropeptide/antagonist applications and behavioral analysis will determine whether specific patterns of electrical activity recorded in the network of the cockroach circadian clock are causally related to neuropeptide-dependent control of behavior.
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Affiliation(s)
- Pablo Rojas
- Theoretical Physics, University of Kassel, Kassel, Germany
| | - Jenny A. Plath
- Animal Physiology, University of Kassel, Kassel, Germany
| | - Julia Gestrich
- Animal Physiology, University of Kassel, Kassel, Germany
| | - Bharath Ananthasubramaniam
- Institute for Theoretical Biology, Humboldt University of Berlin and Charité Universitätsmedizin, Berlin, Germany
| | - Martin E. Garcia
- Theoretical Physics, University of Kassel, Kassel, Germany
- Center for Interdisciplinary Nanostructure Science and Technology (CINSaT), University of Kassel, Kassel, Germany
| | - Hanspeter Herzel
- Institute for Theoretical Biology, Humboldt University of Berlin and Charité Universitätsmedizin, Berlin, Germany
| | - Monika Stengl
- Animal Physiology, University of Kassel, Kassel, Germany
- Center for Interdisciplinary Nanostructure Science and Technology (CINSaT), University of Kassel, Kassel, Germany
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8
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Lazaro MT, Taxidis J, Shuman T, Bachmutsky I, Ikrar T, Santos R, Marcello GM, Mylavarapu A, Chandra S, Foreman A, Goli R, Tran D, Sharma N, Azhdam M, Dong H, Choe KY, Peñagarikano O, Masmanidis SC, Rácz B, Xu X, Geschwind DH, Golshani P. Reduced Prefrontal Synaptic Connectivity and Disturbed Oscillatory Population Dynamics in the CNTNAP2 Model of Autism. Cell Rep 2019; 27:2567-2578.e6. [PMID: 31141683 PMCID: PMC6553483 DOI: 10.1016/j.celrep.2019.05.006] [Citation(s) in RCA: 67] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2018] [Revised: 02/20/2019] [Accepted: 04/30/2019] [Indexed: 11/25/2022] Open
Abstract
Loss-of-function mutations in CNTNAP2 cause a syndromic form of autism spectrum disorder in humans and produce social deficits, repetitive behaviors, and seizures in mice. However, the functional effects of these mutations at cellular and circuit levels remain elusive. Using laser-scanning photostimulation, whole-cell recordings, and electron microscopy, we found a dramatic decrease in excitatory and inhibitory synaptic inputs onto L2/3 pyramidal neurons of the medial prefrontal cortex (mPFC) of Cntnap2 knockout (KO) mice, concurrent with reduced spines and synapses, despite normal dendritic complexity and intrinsic excitability. Moreover, recording of mPFC local field potentials (LFPs) and unit spiking in vivo revealed increased activity in inhibitory neurons, reduced phase-locking to delta and theta oscillations, and delayed phase preference during locomotion. Excitatory neurons showed similar phase modulation changes at delta frequencies. Finally, pairwise correlations increased during immobility in KO mice. Thus, reduced synaptic inputs can yield perturbed temporal coordination of neuronal firing in cortical ensembles.
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Affiliation(s)
- Maria T Lazaro
- Interdepartmental Program for Neuroscience, UCLA, Los Angeles, CA, USA; Center for Neurobehavioral Genetics, Semel Institute, UCLA, Los Angeles, CA, USA; Department of Neurology, David Geffen School of Medicine, UCLA, Los Angeles, CA, USA
| | - Jiannis Taxidis
- Department of Neurology, David Geffen School of Medicine, UCLA, Los Angeles, CA, USA; Integrative Center for Learning and Memory, Brain Research Institute, UCLA, Los Angeles, CA, USA
| | - Tristan Shuman
- Department of Neurology, David Geffen School of Medicine, UCLA, Los Angeles, CA, USA; Integrative Center for Learning and Memory, Brain Research Institute, UCLA, Los Angeles, CA, USA; Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Iris Bachmutsky
- Department of Neurology, David Geffen School of Medicine, UCLA, Los Angeles, CA, USA
| | - Taruna Ikrar
- Department of Anatomy and Neurobiology, UC Irvine, Irvine, CA, USA
| | - Rommel Santos
- Department of Anatomy and Neurobiology, UC Irvine, Irvine, CA, USA
| | - G Mark Marcello
- Department of Anatomy and Histology, University of Veterinary Medicine, Budapest, Hungary
| | - Apoorva Mylavarapu
- Department of Neurology, David Geffen School of Medicine, UCLA, Los Angeles, CA, USA
| | - Swasty Chandra
- Department of Neurology, David Geffen School of Medicine, UCLA, Los Angeles, CA, USA
| | - Allison Foreman
- Department of Neurology, David Geffen School of Medicine, UCLA, Los Angeles, CA, USA
| | - Rachna Goli
- Department of Neurology, David Geffen School of Medicine, UCLA, Los Angeles, CA, USA
| | - Duy Tran
- Department of Neurology, David Geffen School of Medicine, UCLA, Los Angeles, CA, USA
| | - Nikhil Sharma
- Department of Neurology, David Geffen School of Medicine, UCLA, Los Angeles, CA, USA
| | - Michelle Azhdam
- Department of Neurology, David Geffen School of Medicine, UCLA, Los Angeles, CA, USA
| | - Hongmei Dong
- Department of Neurology, David Geffen School of Medicine, UCLA, Los Angeles, CA, USA
| | - Katrina Y Choe
- Center for Neurobehavioral Genetics, Semel Institute, UCLA, Los Angeles, CA, USA
| | - Olga Peñagarikano
- Department of Pharmacology, School of Medicine, University of the Basque Country (UPV/EHU), Vizcaya, Spain; Centro de Investigación Biomédica en Red en Salud Mental (CIBERSAM), Madrid, Spain
| | - Sotiris C Masmanidis
- Integrative Center for Learning and Memory, Brain Research Institute, UCLA, Los Angeles, CA, USA
| | - Bence Rácz
- Department of Anatomy and Histology, University of Veterinary Medicine, Budapest, Hungary
| | - Xiangmin Xu
- Department of Anatomy and Neurobiology, UC Irvine, Irvine, CA, USA
| | - Daniel H Geschwind
- Center for Neurobehavioral Genetics, Semel Institute, UCLA, Los Angeles, CA, USA; Department of Neurology, David Geffen School of Medicine, UCLA, Los Angeles, CA, USA; Center for Autism Research and Treatment, Semel Institute, UCLA, Los Angeles, CA, USA; Intellectual Development and Disabilities Research Center, UCLA, Los Angeles, CA, USA.
| | - Peyman Golshani
- Department of Neurology, David Geffen School of Medicine, UCLA, Los Angeles, CA, USA; Integrative Center for Learning and Memory, Brain Research Institute, UCLA, Los Angeles, CA, USA; Intellectual Development and Disabilities Research Center, UCLA, Los Angeles, CA, USA; West Los Angeles VA Medical Center, Los Angeles, CA.
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Development of Local Circuit Connections to Hilar Mossy Cells in the Mouse Dentate Gyrus. eNeuro 2019; 6:eN-NWR-0370-18. [PMID: 30937358 PMCID: PMC6439204 DOI: 10.1523/eneuro.0370-18.2019] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2018] [Revised: 02/15/2019] [Accepted: 02/22/2019] [Indexed: 12/14/2022] Open
Abstract
Hilar mossy cells in the dentate gyrus (DG) shape the firing and function of the hippocampal circuit. However, the neural circuitry providing afferent input to mossy cells is incompletely understood, and little is known about the development of these inputs. Thus, we used whole-cell recording and laser scanning photostimulation (LSPS) to characterize the developmental trajectory of local excitatory and inhibitory synaptic inputs to mossy cells in the mouse hippocampus. Hilar mossy cells were targeted by visualizing non-red fluorescent cells in the dentate hilus of GAD2-Cre; Ai9 mice that expressed tdTomato in GAD+ neurons, and were confirmed by post hoc morphological characterization. Our results show that at postnatal day (P)6–P7, mossy cells received more excitatory input from neurons in the proximal CA3 versus those in the DG. In contrast, at P13–P14 and P21–P28, the largest source of excitatory input originated in DG cells, while the strength of CA3 and hilar inputs declined. A developmental trend was also evident for inhibitory inputs. Overall inhibitory input at P6–P7 was weak, while inhibitory inputs from the DG cell layer and the hilus predominated at P13–P14 and P21–P28. The strength of local DG excitation and inhibition to mossy cells peaked at P13–P14 and decreased slightly in older P21–P28 mice. Together, these data provide new detailed information on the development of local synaptic connectivity of mossy cells, and suggests mechanisms through which developmental changes in local circuit inputs to hilar mossy cells shape their physiology and vulnerability to injury during postnatal periods.
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Prenatal one-carbon metabolism dysregulation programs schizophrenia-like deficits. Mol Psychiatry 2018; 23:282-294. [PMID: 28809400 PMCID: PMC6432924 DOI: 10.1038/mp.2017.164] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/03/2017] [Revised: 06/20/2017] [Accepted: 06/21/2017] [Indexed: 12/13/2022]
Abstract
The methionine-folate cycle-dependent one-carbon metabolism is implicated in the pathophysiology of schizophrenia. Since schizophrenia is a developmental disorder, we examined the effects that perturbation of the one-carbon metabolism during gestation has on mice progeny. Pregnant mice were administered methionine equivalent to double their daily intake during the last week of gestation. Their progeny (MET mice) exhibited schizophrenia-like social deficits, cognitive impairments and elevated stereotypy, decreased neurogenesis and synaptic plasticity, and abnormally reduced local excitatory synaptic connections in CA1 neurons. Neural transcript expression of only one gene, encoding the Npas4 transcription factor, was >twofold altered (downregulated) in MET mice; strikingly, similar Npas4 downregulation occurred in the prefrontal cortex of human patients with schizophrenia. Finally, therapeutic actions of typical (haloperidol) and atypical (clozapine) antipsychotics in MET mice mimicked effects in human schizophrenia patients. Our data support the validity of MET mice as a model for schizophrenia, and uncover methionine metabolism as a potential preventive and/or therapeutic target.
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Local and Long-Range Circuit Connections to Hilar Mossy Cells in the Dentate Gyrus. eNeuro 2017; 4:eN-NWR-0097-17. [PMID: 28451637 PMCID: PMC5396130 DOI: 10.1523/eneuro.0097-17.2017] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2017] [Revised: 04/03/2017] [Accepted: 04/06/2017] [Indexed: 01/04/2023] Open
Abstract
Hilar mossy cells are the prominent glutamatergic cell type in the dentate hilus of the dentate gyrus (DG); they have been proposed to have critical roles in the DG network. To better understand how mossy cells contribute to DG function, we have applied new viral genetic and functional circuit mapping approaches to quantitatively map and compare local and long-range circuit connections of mossy cells and dentate granule cells in the mouse. The great majority of inputs to mossy cells consist of two parallel inputs from within the DG: an excitatory input pathway from dentate granule cells and an inhibitory input pathway from local DG inhibitory neurons. Mossy cells also receive a moderate degree of excitatory and inhibitory CA3 input from proximal CA3 subfields. Long range inputs to mossy cells are numerically sparse, and they are only identified readily from the medial septum and the septofimbrial nucleus. In comparison, dentate granule cells receive most of their inputs from the entorhinal cortex. The granule cells receive significant synaptic inputs from the hilus and the medial septum, and they also receive direct inputs from both distal and proximal CA3 subfields, which has been underdescribed in the existing literature. Our slice-based physiological mapping studies further supported the identified circuit connections of mossy cells and granule cells. Together, our data suggest that hilar mossy cells are major local circuit integrators and they exert modulation of the activity of dentate granule cells as well as the CA3 region through "back-projection" pathways.
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Merel J, Shababo B, Naka A, Adesnik H, Paninski L. Bayesian methods for event analysis of intracellular currents. J Neurosci Methods 2016; 269:21-32. [DOI: 10.1016/j.jneumeth.2016.05.015] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2016] [Revised: 05/13/2016] [Accepted: 05/16/2016] [Indexed: 01/04/2023]
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13
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Xu X, Ikrar T, Sun Y, Santos R, Holmes TC, Francesconi W, Berton F. High-resolution and cell-type-specific photostimulation mapping shows weak excitatory vs. strong inhibitory inputs in the bed nucleus of the stria terminalis. J Neurophysiol 2016; 115:3204-16. [PMID: 27052587 DOI: 10.1152/jn.01148.2015] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2015] [Accepted: 04/04/2016] [Indexed: 11/22/2022] Open
Abstract
The bed nucleus of the stria terminalis (BNST) is a key component of the extended amygdala and has been implicated in anxiety and addiction. As individual neurons function within neural circuits, it is important to understand local microcircuits and larger network connections of identified neuronal types and understand how maladaptive changes in the BNST neural networks are induced by stress and drug abuse. However, due to limitations of classic anatomical and physiological methods, the local circuit organization of synaptic inputs to specific BNST neuron types is not well understood. In this study, we report on the application of high-resolution and cell-type-specific photostimulation methodology developed in our laboratory to local circuit mapping in the BNST. Under calibrated experimental conditions, laser photostimulation via glutamate uncaging or channelrhodopsin-2 photoactivation evokes spiking of BNST neurons perisomatically, without activating spikes from axons of passage or distal dendrites. Whole cell recordings, combined with spatially restricted photostimulation of presynaptic neurons at many different locations over a large region, allow high-resolution mapping of presynaptic input sources to single recorded neurons in the BNST. We constructed maps of synaptic inputs impinging onto corticotrophin-releasing hormone-expressing (CRH+) BNST neurons in the dorsolateral BNST and found that the CRH+ neurons receive predominant local inhibitory synaptic connections with very weak excitatory connections. Through cell-type-specific optogenetic stimulation mapping, we generated maps of somatostatin-expressing neuron-specific inhibitory inputs to BNST neurons. Taken together, the photostimulation-based techniques offer us powerful tools for determining the functional organization of local circuits of specific BNST neuron types.
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Affiliation(s)
- Xiangmin Xu
- Department of Anatomy and Neurobiology, School of Medicine, University of California, Irvine, California; Department of Biomedical Engineering, University of California, Irvine, California; Department of Microbiology and Molecular Genetics, University of California, Irvine, California;
| | - Taruna Ikrar
- Department of Anatomy and Neurobiology, School of Medicine, University of California, Irvine, California
| | - Yanjun Sun
- Department of Anatomy and Neurobiology, School of Medicine, University of California, Irvine, California
| | - Rommel Santos
- Department of Anatomy and Neurobiology, School of Medicine, University of California, Irvine, California
| | - Todd C Holmes
- Department of Physiology and Biophysics, School of Medicine, University of California, Irvine, California
| | - Walter Francesconi
- Department of Molecular and Cellular Neuroscience, The Scripps Research Institute, La Jolla, California; and
| | - Fulvia Berton
- Department of Chemical Physiology, The Scripps Research Institute, La Jolla, California
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14
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Xu X, Olivas ND, Ikrar T, Peng T, Holmes TC, Nie Q, Shi Y. Primary visual cortex shows laminar-specific and balanced circuit organization of excitatory and inhibitory synaptic connectivity. J Physiol 2016; 594:1891-910. [PMID: 26844927 DOI: 10.1113/jp271891] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2015] [Accepted: 01/27/2016] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS Using functional mapping assays, we conducted a quantitative assessment of both excitatory and inhibitory synaptic laminar connections to excitatory neurons in layers 2/3-6 of the mouse visual cortex (V1). Laminar-specific synaptic wiring diagrams of excitatory neurons were constructed on the basis of circuit mapping. The present study reveals that that excitatory and inhibitory synaptic connectivity is spatially balanced across excitatory neuronal networks in V1. ABSTRACT In the mammalian neocortex, excitatory neurons provide excitation in both columnar and laminar dimensions, which is modulated further by inhibitory neurons. However, our understanding of intracortical excitatory and inhibitory synaptic inputs in relation to principal excitatory neurons remains incomplete, and it is unclear how local excitatory and inhibitory synaptic connections to excitatory neurons are spatially organized on a layer-by-layer basis. In the present study, we combined whole cell recordings with laser scanning photostimulation via glutamate uncaging to map excitatory and inhibitory synaptic inputs to single excitatory neurons throughout cortical layers 2/3-6 in the mouse primary visual cortex (V1). We find that synaptic input sources of excitatory neurons span the radial columns of laminar microcircuits, and excitatory neurons in different V1 laminae exhibit distinct patterns of layer-specific organization of excitatory inputs. Remarkably, the spatial extent of inhibitory inputs of excitatory neurons for a given layer closely mirrors that of their excitatory input sources, indicating that excitatory and inhibitory synaptic connectivity is spatially balanced across excitatory neuronal networks. Strong interlaminar inhibitory inputs are found, particularly for excitatory neurons in layers 2/3 and 5. This differs from earlier studies reporting that inhibitory cortical connections to excitatory neurons are generally localized within the same cortical layer. On the basis of the functional mapping assays, we conducted a quantitative assessment of both excitatory and inhibitory synaptic laminar connections to excitatory cells at single cell resolution, establishing precise layer-by-layer synaptic wiring diagrams of excitatory neurons in the visual cortex.
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Affiliation(s)
- Xiangmin Xu
- Department of Anatomy and Neurobiology, School of Medicine.,Department of Biomedical Engineering
| | - Nicholas D Olivas
- Department of Anatomy and Neurobiology, School of Medicine.,Present address: Department of Neurobiology, David Geffen School of Medicine, University of California, Los Angeles, CA, USA
| | - Taruna Ikrar
- Department of Anatomy and Neurobiology, School of Medicine
| | - Tao Peng
- Department of Mathematics.,Center for Complex Biological Systems
| | - Todd C Holmes
- Department of Physiology and Biophysics, School of Medicine, University of California, Irvine, CA, USA
| | - Qing Nie
- Department of Biomedical Engineering.,Department of Mathematics.,Center for Complex Biological Systems
| | - Yulin Shi
- Department of Anatomy and Neurobiology, School of Medicine
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15
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Shi Y, Ikrar T, Olivas ND, Xu X. Bidirectional global spontaneous network activity precedes the canonical unidirectional circuit organization in the developing hippocampus. J Comp Neurol 2015; 522:2191-208. [PMID: 24357090 PMCID: PMC4293468 DOI: 10.1002/cne.23528] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2013] [Revised: 11/22/2013] [Accepted: 12/17/2013] [Indexed: 11/27/2022]
Abstract
Spontaneous network activity is believed to sculpt developing neural circuits. Spontaneous giant depolarizing potentials (GDPs) were first identified with single-cell recordings from rat CA3 pyramidal neurons, but here we identify and characterize a large-scale spontaneous network activity we term global network activation (GNA) in the developing mouse hippocampal slices, which is measured macroscopically by fast voltage-sensitive dye imaging. The initiation and propagation of GNA in the mouse is largely GABA-independent and dominated by glutamatergic transmission via AMPA receptors. Despite the fact that signal propagation in the adult hippocampus is strongly unidirectional through the canonical trisynaptic circuit (dentate gyrus [DG] to CA3 to CA1), spontaneous GNA in the developing hippocampus originates in distal CA3 and propagates both forward to CA1 and backward to DG. Photostimulation-evoked GNA also shows prominent backward propagation in the developing hippocampus from CA3 to DG. Mouse GNA is strongly correlated to electrophysiological recordings of highly localized single-cell and local field potential events. Photostimulation mapping of neural circuitry demonstrates that the enhancement of local circuit connections to excitatory pyramidal neurons occurs over the same time course as GNA and reveals the underlying pathways accounting for GNA backward propagation from CA3 to DG. The disappearance of GNA coincides with a transition to the adult-like unidirectional circuit organization at about 2 weeks of age. Taken together, our findings strongly suggest a critical link between GNA activity and maturation of functional circuit connections in the developing hippocampus.
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Affiliation(s)
- Yulin Shi
- Department of Anatomy and Neurobiology, School of Medicine, University of California, Irvine, California, 92697-1275
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16
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San Antonio A, Liban K, Ikrar T, Tsyganovskiy E, Xu X. Distinct physiological and developmental properties of hippocampal CA2 subfield revealed by using anti-Purkinje cell protein 4 (PCP4) immunostaining. J Comp Neurol 2014; 522:1333-54. [PMID: 24166578 PMCID: PMC4001794 DOI: 10.1002/cne.23486] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2013] [Revised: 10/14/2013] [Accepted: 10/15/2013] [Indexed: 12/04/2022]
Abstract
The hippocampal CA2 subfield was initially identified by Lorente de Nó as an anatomically distinct region based on its cytoarchitectural features. Although there is an enormous body of literature on other hippocampal subfields (CA1 and CA3), relatively little is known about the physiological and developmental properties of CA2. Here we report identification of the CA2 region in the mouse by immunostaining with a Purkinje cell protein 4 (PCP4) antibody, which effectively delineates CA3/CA2 and CA2/CA1 borders and agrees well with previous cytoarchitectural definitions of CA2. The PCP4 immunostaining–delineated CA2 neurons have distinguishable differences in cell morphology, physiology, and synaptic circuit connections compared with distal CA3 and proximal CA1 regions. The average somatic sizes of excitatory cells differ across CA1–3, with the smallest to largest somatic size being CA1<CA2<CA3. CA2 excitatory cells have dense dendritic spines, but do not have thorny excrescences associated with bordering CA3 neurons. Photostimulation functional circuit mapping shows that CA2 excitatory neurons receives extensive synaptic input from CA3, but no detectable input from the dentate gyrus. CA2 excitatory cells also differ significantly from CA3 cells in intrinsic electrophysiological parameters, such as membrane capacitance and spiking rates. Although CA2 neurons differ from CA1 neurons for PCP4 and other marker expressions, these neurons have less distinct neurophysiological and morphological properties. Developmental examination revealed that PCP4 immunostaining first appears at postnatal day 4–5 and becomes successively more refined around CA2 until reaching adult form by postnatal day 21. J. Comp. Neurol. J. Comp. Neurol. 522:1333–1354, 2014. © 2013 Wiley Periodicals, Inc.
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Affiliation(s)
- Andrew San Antonio
- Department of Anatomy and Neurobiology, School of Medicine, University of California, Irvine, California, 92697-1275
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17
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Shi Y, Veidenbaum AV, Nicolau A, Xu X. Large-scale neural circuit mapping data analysis accelerated with the graphical processing unit (GPU). J Neurosci Methods 2014; 239:1-10. [PMID: 25277633 DOI: 10.1016/j.jneumeth.2014.09.022] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2014] [Revised: 09/19/2014] [Accepted: 09/22/2014] [Indexed: 10/24/2022]
Abstract
BACKGROUND Modern neuroscience research demands computing power. Neural circuit mapping studies such as those using laser scanning photostimulation (LSPS) produce large amounts of data and require intensive computation for post hoc processing and analysis. NEW METHOD Here we report on the design and implementation of a cost-effective desktop computer system for accelerated experimental data processing with recent GPU computing technology. A new version of Matlab software with GPU enabled functions is used to develop programs that run on Nvidia GPUs to harness their parallel computing power. RESULTS We evaluated both the central processing unit (CPU) and GPU-enabled computational performance of our system in benchmark testing and practical applications. The experimental results show that the GPU-CPU co-processing of simulated data and actual LSPS experimental data clearly outperformed the multi-core CPU with up to a 22× speedup, depending on computational tasks. Further, we present a comparison of numerical accuracy between GPU and CPU computation to verify the precision of GPU computation. In addition, we show how GPUs can be effectively adapted to improve the performance of commercial image processing software such as Adobe Photoshop. COMPARISON WITH EXISTING METHOD(S) To our best knowledge, this is the first demonstration of GPU application in neural circuit mapping and electrophysiology-based data processing. CONCLUSIONS Together, GPU enabled computation enhances our ability to process large-scale data sets derived from neural circuit mapping studies, allowing for increased processing speeds while retaining data precision.
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Affiliation(s)
- Yulin Shi
- Department of Anatomy and Neurobiology, School of Medicine, University of California, Irvine, CA 92697-1275, United States
| | - Alexander V Veidenbaum
- Department of Computer Science, University of California, Irvine, CA 92697-3435, United States
| | - Alex Nicolau
- Department of Computer Science, University of California, Irvine, CA 92697-3435, United States
| | - Xiangmin Xu
- Department of Anatomy and Neurobiology, School of Medicine, University of California, Irvine, CA 92697-1275, United States; Department of Biomedical Engineering, University of California, Irvine, CA 92697-2715, United States; Department of Electrical Engineering and Computer Science, University of California, Irvine, CA 92697-2625, United States.
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18
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Kuhlman SJ, Olivas ND, Tring E, Ikrar T, Xu X, Trachtenberg JT. A disinhibitory microcircuit initiates critical-period plasticity in the visual cortex. Nature 2013; 501:543-6. [PMID: 23975100 PMCID: PMC3962838 DOI: 10.1038/nature12485] [Citation(s) in RCA: 291] [Impact Index Per Article: 26.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2012] [Accepted: 07/17/2013] [Indexed: 11/29/2022]
Abstract
Early sensory experience instructs the maturation of neural circuitry in cortex 1,2. This has been extensively studied in the primary visual cortex where loss of vision to one eye permanently degrades cortical responsiveness to that eye 3,4, a phenomenon known as ocular dominance plasticity (ODP). Cortical inhibition mediates this process 4-6, but the precise role of specific classes of inhibitory neurons in ODP is controversial. Here we report that evoked firing rates of binocular excitatory neurons in primary visual cortex immediately drop by half when vision is restricted to one eye, but gradually return to normal over the following 24 hours, despite the fact that vision remains restricted to one eye. This restoration of binocular-like excitatory firing rates following monocular deprivation results from a rapid, though transient reduction in the firing rates of fast-spiking, parvalbumin-positive (PV) interneurons, which in turn can be attributed to a decrease in local excitatory circuit input onto PV interneurons. This reduction in PV cell evoked responses following monocular lid suture is restricted to the critical period for ODP and appears to be necessary for subsequent shifts in excitatory ODP. Pharmacologically enhancing inhibition at the time of sight deprivation blocks ODP and, conversely, pharmaco-genetic reduction of PV cell firing rates can extend the critical period for ODP. These findings define the microcircuit changes initiating competitive plasticity during critical periods of cortical development. Moreover, they show that the restoration of evoked firing rates of L2/3 pyramidal neurons by PV-specific disinhibition is a key step in the progression of ocular dominance plasticity.
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Affiliation(s)
- Sandra J Kuhlman
- Department of Neurobiology, David Geffen School of Medicine, University of California, Los Angeles, California 90048, USA
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19
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Olivas ND, Quintanar-Zilinskas V, Nenadic Z, Xu X. Laminar circuit organization and response modulation in mouse visual cortex. Front Neural Circuits 2012; 6:70. [PMID: 23060751 PMCID: PMC3464489 DOI: 10.3389/fncir.2012.00070] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2012] [Accepted: 09/12/2012] [Indexed: 01/03/2023] Open
Abstract
The mouse has become an increasingly important animal model for visual system studies, but few studies have investigated local functional circuit organization of mouse visual cortex. Here we used our newly developed mapping technique combining laser scanning photostimulation (LSPS) with fast voltage-sensitive dye (VSD) imaging to examine the spatial organization and temporal dynamics of laminar circuit responses in living slice preparations of mouse primary visual cortex (V1). During experiments, LSPS using caged glutamate provided spatially restricted neuronal activation in a specific cortical layer, and evoked responses from the stimulated layer to its functionally connected regions were detected by VSD imaging. In this study, we first provided a detailed analysis of spatiotemporal activation patterns at specific V1 laminar locations and measured local circuit connectivity. Then we examined the role of cortical inhibition in the propagation of evoked cortical responses by comparing circuit activity patterns in control and in the presence of GABAa receptor antagonists. We found that GABAergic inhibition was critical in restricting layer-specific excitatory activity spread and maintaining topographical projections. In addition, we investigated how AMPA and NMDA receptors influenced cortical responses and found that blocking AMPA receptors abolished interlaminar functional projections, and the NMDA receptor activity was important in controlling visual cortical circuit excitability and modulating activity propagation. The NMDA receptor antagonist reduced neuronal population activity in time-dependent and laminar-specific manners. Finally, we used the quantitative information derived from the mapping experiments and presented computational modeling analysis of V1 circuit organization. Taken together, the present study has provided important new information about mouse V1 circuit organization and response modulation.
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Affiliation(s)
- Nicholas D Olivas
- Department of Anatomy and Neurobiology, School of Medicine, University of California Irvine, CA, USA
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20
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Pernía-Andrade AJ, Goswami SP, Stickler Y, Fröbe U, Schlögl A, Jonas P. A deconvolution-based method with high sensitivity and temporal resolution for detection of spontaneous synaptic currents in vitro and in vivo. Biophys J 2012; 103:1429-39. [PMID: 23062335 DOI: 10.1016/j.bpj.2012.08.039] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2012] [Revised: 08/15/2012] [Accepted: 08/20/2012] [Indexed: 01/25/2023] Open
Abstract
Spontaneous postsynaptic currents (PSCs) provide key information about the mechanisms of synaptic transmission and the activity modes of neuronal networks. However, detecting spontaneous PSCs in vitro and in vivo has been challenging, because of the small amplitude, the variable kinetics, and the undefined time of generation of these events. Here, we describe a, to our knowledge, new method for detecting spontaneous synaptic events by deconvolution, using a template that approximates the average time course of spontaneous PSCs. A recorded PSC trace is deconvolved from the template, resulting in a series of delta-like functions. The maxima of these delta-like events are reliably detected, revealing the precise onset times of the spontaneous PSCs. Among all detection methods, the deconvolution-based method has a unique temporal resolution, allowing the detection of individual events in high-frequency bursts. Furthermore, the deconvolution-based method has a high amplitude resolution, because deconvolution can substantially increase the signal/noise ratio. When tested against previously published methods using experimental data, the deconvolution-based method was superior for spontaneous PSCs recorded in vivo. Using the high-resolution deconvolution-based detection algorithm, we show that the frequency of spontaneous excitatory postsynaptic currents in dentate gyrus granule cells is 4.5 times higher in vivo than in vitro.
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21
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Ikrar T, Olivas ND, Shi Y, Xu X. Mapping inhibitory neuronal circuits by laser scanning photostimulation. J Vis Exp 2011:3109. [PMID: 22006064 DOI: 10.3791/3109] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Inhibitory neurons are crucial to cortical function. They comprise about 20% of the entire cortical neuronal population and can be further subdivided into diverse subtypes based on their immunochemical, morphological, and physiological properties. Although previous research has revealed much about intrinsic properties of individual types of inhibitory neurons, knowledge about their local circuit connections is still relatively limited. Given that each individual neuron's function is shaped by its excitatory and inhibitory synaptic input within cortical circuits, we have been using laser scanning photostimulation (LSPS) to map local circuit connections to specific inhibitory cell types. Compared to conventional electrical stimulation or glutamate puff stimulation, LSPS has unique advantages allowing for extensive mapping and quantitative analysis of local functional inputs to individually recorded neurons. Laser photostimulation via glutamate uncaging selectively activates neurons perisomatically, without activating axons of passage or distal dendrites, which ensures a sub-laminar mapping resolution. The sensitivity and efficiency of LSPS for mapping inputs from many stimulation sites over a large region are well suited for cortical circuit analysis. Here we introduce the technique of LSPS combined with whole-cell patch clamping for local inhibitory circuit mapping. Targeted recordings of specific inhibitory cell types are facilitated by use of transgenic mice expressing green fluorescent proteins (GFP) in limited inhibitory neuron populations in the cortex, which enables consistent sampling of the targeted cell types and unambiguous identification of the cell types recorded. As for LSPS mapping, we outline the system instrumentation, describe the experimental procedure and data acquisition, and present examples of circuit mapping in mouse primary somatosensory cortex. As illustrated in our experiments, caged glutamate is activated in a spatially restricted region of the brain slice by UV laser photolysis; simultaneous voltage-clamp recordings allow detection of photostimulation-evoked synaptic responses. Maps of either excitatory or inhibitory synaptic input to the targeted neuron are generated by scanning the laser beam to stimulate hundreds of potential presynaptic sites. Thus, LSPS enables the construction of detailed maps of synaptic inputs impinging onto specific types of inhibitory neurons through repeated experiments. Taken together, the photostimulation-based technique offers neuroscientists a powerful tool for determining the functional organization of local cortical circuits.
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Affiliation(s)
- Taruna Ikrar
- Department of Anatomy and Neurobiology, School of Medicine, University of California, Irvine, USA
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