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Zolnik TA, Bronec A, Ross A, Staab M, Sachdev RNS, Molnár Z, Eickholt BJ, Larkum ME. Layer 6b controls brain state via apical dendrites and the higher-order thalamocortical system. Neuron 2024; 112:805-820.e4. [PMID: 38101395 DOI: 10.1016/j.neuron.2023.11.021] [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: 03/10/2023] [Revised: 09/11/2023] [Accepted: 11/18/2023] [Indexed: 12/17/2023]
Abstract
The deepest layer of the cortex (layer 6b [L6b]) contains relatively few neurons, but it is the only cortical layer responsive to the potent wake-promoting neuropeptide orexin/hypocretin. Can these few neurons significantly influence brain state? Here, we show that L6b-photoactivation causes a surprisingly robust enhancement of attention-associated high-gamma oscillations and population spiking while abolishing slow waves in sleep-deprived mice. To explain this powerful impact on brain state, we investigated L6b's synaptic output using optogenetics, electrophysiology, and monoCaTChR ex vivo. We found powerful output in the higher-order thalamus and apical dendrites of L5 pyramidal neurons, via L1a and L5a, as well as in superior colliculus and L6 interneurons. L6b subpopulations with distinct morphologies and short- and long-term plasticities project to these diverse targets. The L1a-targeting subpopulation triggered powerful NMDA-receptor-dependent spikes that elicited burst firing in L5. We conclude that orexin/hypocretin-activated cortical neurons form a multifaceted, fine-tuned circuit for the sustained control of the higher-order thalamocortical system.
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Affiliation(s)
- Timothy Adam Zolnik
- Department of Biochemistry, Charité Universitätsmedizin Berlin, Berlin 10117, Germany; Department of Biology, Humboldt Universität zu Berlin, Berlin 10117, Germany.
| | - Anna Bronec
- Department of Biology, Humboldt Universität zu Berlin, Berlin 10117, Germany
| | - Annemarie Ross
- Department of Biology, Humboldt Universität zu Berlin, Berlin 10117, Germany
| | - Marcel Staab
- Department of Biology, Humboldt Universität zu Berlin, Berlin 10117, Germany
| | - Robert N S Sachdev
- Department of Biology, Humboldt Universität zu Berlin, Berlin 10117, Germany
| | - Zoltán Molnár
- Department of Biochemistry, Charité Universitätsmedizin Berlin, Berlin 10117, Germany; Department of Physiology, Anatomy, and Genetics, University of Oxford, Parks Road, Sherrington Building, Oxford OX1 3PT, UK
| | | | - Matthew Evan Larkum
- Department of Biology, Humboldt Universität zu Berlin, Berlin 10117, Germany.
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2
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Feldmeyer D. Structure and function of neocortical layer 6b. Front Cell Neurosci 2023; 17:1257803. [PMID: 37744882 PMCID: PMC10516558 DOI: 10.3389/fncel.2023.1257803] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2023] [Accepted: 08/14/2023] [Indexed: 09/26/2023] Open
Abstract
Cortical layer 6b is considered by many to be a remnant of the subplate that forms during early stages of neocortical development, but its role in the adult is not well understood. Its neuronal complement has only recently become the subject of systematic studies, and its axonal projections and synaptic input structures have remained largely unexplored despite decades of research into neocortical function. In recent years, however, layer 6b (L6b) has attracted increasing attention and its functional role is beginning to be elucidated. In this review, I will attempt to provide an overview of what is currently known about the excitatory and inhibitory neurons in this layer, their pre- and postsynaptic connectivity, and their functional implications. Similarities and differences between different cortical areas will be highlighted. Finally, layer 6b neurons are highly responsive to several neuropeptides such as orexin/hypocretin, neurotensin and cholecystokinin, in some cases exclusively. They are also strongly controlled by neurotransmitters such as acetylcholine and norepinephrine. The interaction of these neuromodulators with L6b microcircuitry and its functional consequences will also be discussed.
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Affiliation(s)
- Dirk Feldmeyer
- Research Centre Jülich, Institute of Neuroscience and Medicine 10 (INM-10), Jülich, Germany
- Department of Psychiatry, Psychotherapy, and Psychosomatics, RWTH Aachen University Hospital, Aachen, Germany
- Jülich-Aachen Research Alliance, Translational Brain Medicine (JARA Brain), Aachen, Germany
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3
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Duffet L, Kosar S, Panniello M, Viberti B, Bracey E, Zych AD, Radoux-Mergault A, Zhou X, Dernic J, Ravotto L, Tsai YC, Figueiredo M, Tyagarajan SK, Weber B, Stoeber M, Gogolla N, Schmidt MH, Adamantidis AR, Fellin T, Burdakov D, Patriarchi T. A genetically encoded sensor for in vivo imaging of orexin neuropeptides. Nat Methods 2022; 19:231-241. [PMID: 35145320 PMCID: PMC8831244 DOI: 10.1038/s41592-021-01390-2] [Citation(s) in RCA: 45] [Impact Index Per Article: 22.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2021] [Accepted: 12/16/2021] [Indexed: 02/07/2023]
Abstract
Orexins (also called hypocretins) are hypothalamic neuropeptides that carry out essential functions in the central nervous system; however, little is known about their release and range of action in vivo owing to the limited resolution of current detection technologies. Here we developed a genetically encoded orexin sensor (OxLight1) based on the engineering of circularly permutated green fluorescent protein into the human type-2 orexin receptor. In mice OxLight1 detects optogenetically evoked release of endogenous orexins in vivo with high sensitivity. Photometry recordings of OxLight1 in mice show rapid orexin release associated with spontaneous running behavior, acute stress and sleep-to-wake transitions in different brain areas. Moreover, two-photon imaging of OxLight1 reveals orexin release in layer 2/3 of the mouse somatosensory cortex during emergence from anesthesia. Thus, OxLight1 enables sensitive and direct optical detection of orexin neuropeptides with high spatiotemporal resolution in living animals.
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Affiliation(s)
- Loïc Duffet
- Institute of Pharmacology and Toxicology, University of Zurich, Zurich, Switzerland
| | - Seher Kosar
- Department of Health Sciences and Technology, ETH Zurich, Zurich, Switzerland
| | - Mariangela Panniello
- Optical Approaches to Brain Function Laboratory, Istituto Italiano di Tecnologia, Genova, Italy
| | - Bianca Viberti
- Center for Experimental Neurology (ZEN), Department of Neurology, Inselspital University Hospital Bern, University of Bern, Bern, Switzerland
- Department of Biomedical Research, University of Bern, Bern, Switzerland
| | - Edward Bracey
- Department of Health Sciences and Technology, ETH Zurich, Zurich, Switzerland
| | - Anna D Zych
- Circuits for Emotion Research Group, Max Planck Institute of Neurobiology, Martinsried, Germany
- International Max Planck Research School for Translational Psychiatry (IMPRS-TP), Munich, Germany
| | | | - Xuehan Zhou
- Institute of Pharmacology and Toxicology, University of Zurich, Zurich, Switzerland
| | - Jan Dernic
- Institute of Pharmacology and Toxicology, University of Zurich, Zurich, Switzerland
| | - Luca Ravotto
- Institute of Pharmacology and Toxicology, University of Zurich, Zurich, Switzerland
| | - Yuan-Chen Tsai
- Institute of Pharmacology and Toxicology, University of Zurich, Zurich, Switzerland
| | - Marta Figueiredo
- Institute of Pharmacology and Toxicology, University of Zurich, Zurich, Switzerland
| | - Shiva K Tyagarajan
- Institute of Pharmacology and Toxicology, University of Zurich, Zurich, Switzerland
- Optical Approaches to Brain Function Laboratory, Istituto Italiano di Tecnologia, Genova, Italy
| | - Bruno Weber
- Institute of Pharmacology and Toxicology, University of Zurich, Zurich, Switzerland
- Optical Approaches to Brain Function Laboratory, Istituto Italiano di Tecnologia, Genova, Italy
| | - Miriam Stoeber
- Department of Cell Physiology and Metabolism, University of Geneva, Geneva, Switzerland
| | - Nadine Gogolla
- Circuits for Emotion Research Group, Max Planck Institute of Neurobiology, Martinsried, Germany
| | - Markus H Schmidt
- Center for Experimental Neurology (ZEN), Department of Neurology, Inselspital University Hospital Bern, University of Bern, Bern, Switzerland
- Department of Biomedical Research, University of Bern, Bern, Switzerland
| | - Antoine R Adamantidis
- Center for Experimental Neurology (ZEN), Department of Neurology, Inselspital University Hospital Bern, University of Bern, Bern, Switzerland
- Department of Biomedical Research, University of Bern, Bern, Switzerland
| | - Tommaso Fellin
- Optical Approaches to Brain Function Laboratory, Istituto Italiano di Tecnologia, Genova, Italy
| | - Denis Burdakov
- Department of Health Sciences and Technology, ETH Zurich, Zurich, Switzerland
- Neuroscience Center Zurich, University and ETH Zurich, Zurich, Switzerland
| | - Tommaso Patriarchi
- Institute of Pharmacology and Toxicology, University of Zurich, Zurich, Switzerland.
- Neuroscience Center Zurich, University and ETH Zurich, Zurich, Switzerland.
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4
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Valle-Bautista R, Márquez-Valadez B, Fragoso-Cabrera AD, García-López G, Díaz NF, Herrera-López G, Griego E, Galván EJ, Arias-Montaño JA, Molina-Hernández A. Impaired Cortical Cytoarchitecture and Reduced Excitability of Deep-Layer Neurons in the Offspring of Diabetic Rats. Front Cell Dev Biol 2020; 8:564561. [PMID: 33042999 PMCID: PMC7527606 DOI: 10.3389/fcell.2020.564561] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2020] [Accepted: 08/17/2020] [Indexed: 12/26/2022] Open
Abstract
Maternal diabetes has been related to low verbal task scores, impaired fine and gross motor skills, and poor performance in graphic and visuospatial tasks during childhood. The primary motor cortex is important for controlling motor functions, and embryos exposed to high glucose show changes in cell proliferation, migration, and differentiation during corticogenesis. However, the existing studies do not discriminate between embryos with or without neural tube defects, making it difficult to conclude whether the reported changes are related to neural tube defects or other anomalies. Furthermore, postnatal effects on central nervous system cytoarchitecture and function have been scarcely addressed. Through molecular, biochemical, morphological, and electrophysiological approaches, we provide evidence of impaired primary motor cerebral cortex lamination and neuronal function in pups from diabetic rats, showing an altered distribution of SATB2, FOXP2, and TBR1, impaired cell migration and polarity, and decreased excitability of deep-layer cortical neurons, suggesting abnormalities in cortico-cortical and extra-cortical innervation. Furthermore, phase-plot analysis of action potentials suggests changes in the activity of potassium channels. These results indicate that high-glucose insult during development promotes complex changes in migration, neurogenesis, cell polarity establishment, and dendritic arborization, which in turn lead to reduced excitability of deep-layer cortical neurons.
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Affiliation(s)
- Rocío Valle-Bautista
- Departamento de Fisiología, Biofísica y Neurociencias, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, Mexico City, Mexico.,Laboratorio de Investigación en Células Troncales y Biología del Desarrollo, Departamento de Fisiología y Desarrollo Celular, Subdirección de Investigación Biomédica, Instituto Nacional de Perinatología Isidro Espinosa de los Reyes, Mexico City, Mexico
| | - Berenice Márquez-Valadez
- Laboratorio de Investigación en Células Troncales y Biología del Desarrollo, Departamento de Fisiología y Desarrollo Celular, Subdirección de Investigación Biomédica, Instituto Nacional de Perinatología Isidro Espinosa de los Reyes, Mexico City, Mexico
| | - América D Fragoso-Cabrera
- Laboratorio de Investigación en Células Troncales y Biología del Desarrollo, Departamento de Fisiología y Desarrollo Celular, Subdirección de Investigación Biomédica, Instituto Nacional de Perinatología Isidro Espinosa de los Reyes, Mexico City, Mexico
| | - Guadalupe García-López
- Laboratorio de Investigación en Células Troncales y Biología del Desarrollo, Departamento de Fisiología y Desarrollo Celular, Subdirección de Investigación Biomédica, Instituto Nacional de Perinatología Isidro Espinosa de los Reyes, Mexico City, Mexico
| | - Néstor Fabián Díaz
- Laboratorio de Investigación en Células Troncales y Biología del Desarrollo, Departamento de Fisiología y Desarrollo Celular, Subdirección de Investigación Biomédica, Instituto Nacional de Perinatología Isidro Espinosa de los Reyes, Mexico City, Mexico
| | - Gabriel Herrera-López
- Departamento de Farmacobiología, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, Mexico City, Mexico
| | - Ernesto Griego
- Departamento de Farmacobiología, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, Mexico City, Mexico
| | - Emilio J Galván
- Departamento de Farmacobiología, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, Mexico City, Mexico
| | - José-Antonio Arias-Montaño
- Departamento de Fisiología, Biofísica y Neurociencias, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, Mexico City, Mexico
| | - Anayansi Molina-Hernández
- Laboratorio de Investigación en Células Troncales y Biología del Desarrollo, Departamento de Fisiología y Desarrollo Celular, Subdirección de Investigación Biomédica, Instituto Nacional de Perinatología Isidro Espinosa de los Reyes, Mexico City, Mexico
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5
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Rasmussen R, O'Donnell J, Ding F, Nedergaard M. Interstitial ions: A key regulator of state-dependent neural activity? Prog Neurobiol 2020; 193:101802. [PMID: 32413398 PMCID: PMC7331944 DOI: 10.1016/j.pneurobio.2020.101802] [Citation(s) in RCA: 45] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2019] [Revised: 03/24/2020] [Accepted: 03/26/2020] [Indexed: 02/08/2023]
Abstract
Throughout the nervous system, ion gradients drive fundamental processes. Yet, the roles of interstitial ions in brain functioning is largely forgotten. Emerging literature is now revitalizing this area of neuroscience by showing that interstitial cations (K+, Ca2+ and Mg2+) are not static quantities but change dynamically across states such as sleep and locomotion. In turn, these state-dependent changes are capable of sculpting neuronal activity; for example, changing the local interstitial ion composition in the cortex is sufficient for modulating the prevalence of slow-frequency neuronal oscillations, or potentiating the gain of visually evoked responses. Disturbances in interstitial ionic homeostasis may also play a central role in the pathogenesis of central nervous system diseases. For example, impairments in K+ buffering occur in a number of neurodegenerative diseases, and abnormalities in neuronal activity in disease models disappear when interstitial K+ is normalized. Here we provide an overview of the roles of interstitial ions in physiology and pathology. We propose the brain uses interstitial ion signaling as a global mechanism to coordinate its complex activity patterns, and ion homeostasis failure contributes to central nervous system diseases affecting cognitive functions and behavior.
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Affiliation(s)
- Rune Rasmussen
- Center for Translational Neuromedicine, Faculty of Health and Medical Sciences, University of Copenhagen, 2200, Copenhagen, Denmark.
| | - John O'Donnell
- Center for Translational Neuromedicine, University of Rochester Medical Center, Rochester, NY, 14642, United States
| | - Fengfei Ding
- Center for Translational Neuromedicine, University of Rochester Medical Center, Rochester, NY, 14642, United States
| | - Maiken Nedergaard
- Center for Translational Neuromedicine, Faculty of Health and Medical Sciences, University of Copenhagen, 2200, Copenhagen, Denmark; Center for Translational Neuromedicine, University of Rochester Medical Center, Rochester, NY, 14642, United States.
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6
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Williams RH, Black SW, Thomas AM, Piquet J, Cauli B, Kilduff TS. Excitation of Cortical nNOS/NK1R Neurons by Hypocretin 1 is Independent of Sleep Homeostasis. Cereb Cortex 2020; 29:1090-1108. [PMID: 29462275 DOI: 10.1093/cercor/bhy015] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2017] [Accepted: 01/10/2018] [Indexed: 11/14/2022] Open
Abstract
We have proposed that cortical nNOS/NK1R interneurons have a role in sleep homeostasis. The hypocretins (orexins) are wake-promoting neuropeptides and hypocretin/orexin (Hcrt) neurons project to the cortex. Hcrt peptides affect deep layer cortical neurons, and Hcrt receptor 1 (Hcrtr1; Ox1r) mRNA is expressed in cortical nNOS/NK1R cells. Therefore, we investigated whether Hcrt neuron stimulation affects cingulate cortex nNOS/NK1R neurons. Bath application of HCRT1/orexin-A evoked an inward current and membrane depolarization in most nNOS/NK1R cells which persisted in tetrodotoxin; optogenetic stimulation of Hcrt terminals expressing channelrhodopsin-2 confirmed these results, and pharmacological studies determined that HCRTR1 mediated these responses. Single-cell RT-PCR found Hcrtr1 mRNA in 31% of nNOS/NK1R cells without any Hcrtr2 mRNA expression; immunohistochemical studies of Hcrtr1-EGFP mice confirmed that a minority of nNOS/NK1R cells express HCRTR1. When Hcrt neurons degenerated in orexin-tTA;TetO DTA mice, the increased EEG delta power during NREM sleep produced in response to 4 h sleep deprivation and c-FOS expression in cortical nNOS/NK1R cells during recovery sleep were indistinguishable from that of controls. We conclude that Hcrt excitatory input to these deep layer cells is mediated through HCRTR1 but is unlikely to be involved in the putative role of cortical nNOS/NK1R neurons in sleep homeostasis.
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Affiliation(s)
- Rhîannan H Williams
- Center for Neuroscience, Biosciences Division, SRI International, Menlo Park, CA, USA.,Institute for Neurogenomics, Helmholtz Zentrum München, German Research Centre for Environmental Health, Neuherberg, Germany
| | - Sarah W Black
- Center for Neuroscience, Biosciences Division, SRI International, Menlo Park, CA, USA
| | - Alexia M Thomas
- Center for Neuroscience, Biosciences Division, SRI International, Menlo Park, CA, USA
| | - Juliette Piquet
- Sorbonne Universités, UPMC Univ Paris 06, INSERM, CNRS, Neuroscience Paris Seine-Institut de Biologie Paris Seine (NPS-IBPS), Paris, France
| | - Bruno Cauli
- Sorbonne Universités, UPMC Univ Paris 06, INSERM, CNRS, Neuroscience Paris Seine-Institut de Biologie Paris Seine (NPS-IBPS), Paris, France
| | - Thomas S Kilduff
- Center for Neuroscience, Biosciences Division, SRI International, Menlo Park, CA, USA
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7
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Tantirigama MLS, Zolnik T, Judkewitz B, Larkum ME, Sachdev RNS. Perspective on the Multiple Pathways to Changing Brain States. Front Syst Neurosci 2020; 14:23. [PMID: 32457583 PMCID: PMC7225277 DOI: 10.3389/fnsys.2020.00023] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2019] [Accepted: 04/06/2020] [Indexed: 11/13/2022] Open
Abstract
In this review article, we highlight several disparate ideas that are linked to changes in brain state (i.e., sleep to arousal, Down to Up, synchronized to de-synchronized). In any discussion of the brain state, we propose that the cortical pyramidal neuron has a central position. EEG recordings, which typically assess brain state, predominantly reflect the activity of cortical pyramidal neurons. This means that the dominant rhythmic activity that characterizes a particular brain state ultimately has to manifest globally across the pyramidal neuron population. During state transitions, it is the long-range connectivity of these neurons that broadcast the resultant changes in activity to many subcortical targets. Structures like the thalamus, brainstem/hypothalamic neuromodulatory systems, and respiratory systems can also strongly influence brain state, and for many decades we have been uncovering bidirectional pathways that link these structures to state changes in the cerebral cortex. More recently, movement and active behaviors have emerged as powerful drivers of state changes. Each of these systems involve different circuits distributed across the brain. Yet, for a system-wide change in brain state, there must be a collaboration between these circuits that reflects and perhaps triggers the transition between brain states. As we expand our understanding of how brain state changes, our current challenge is to understand how these diverse sets of circuits and pathways interact to produce the changes observed in cortical pyramidal neurons.
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Affiliation(s)
| | | | | | - Matthew E. Larkum
- Institut für Biologie, Neurocure Center for Excellence, Charité Universitätsmedizin Berlin & Humboldt Universität, Berlin, Germany
| | - Robert N. S. Sachdev
- Institut für Biologie, Neurocure Center for Excellence, Charité Universitätsmedizin Berlin & Humboldt Universität, Berlin, Germany
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8
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Case L, Broberger C. Neurotensin Broadly Recruits Inhibition via White Matter Neurons in the Mouse Cerebral Cortex: Synaptic Mechanisms for Decorrelation. Cereb Cortex 2019; 28:2711-2724. [PMID: 28981614 DOI: 10.1093/cercor/bhx149] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2017] [Indexed: 12/30/2022] Open
Abstract
The neuropeptide, neurotensin (NT), inhibits UP state generation in the cerebral cortex and temporally restricts the response to thalamic input, likely by a generalized increase in inhibition. To investigate the cellular and circuit substrate(s) for how a neuropeptide can shift the balance between cortical excitation and inhibition, we performed whole-cell recordings on slice preparations from mice expressing enhanced green fluorescent protein under control of the promoter for the homeobox gene, lhx6 (lhx6-EGFP mice). These mice identify the 2 largest classes of cortical interneurons; FS and low-threshold-spiking inhibitory neurons. In the presence of NT, both types of lhx6-EGFP neurons were excited through a direct, Na+-dependent depolarization, and through an increase in synaptic excitation. Paired recordings identified cortical white matter (WM) neurons as a source of this excitatory input, which was strengthened in the presence of NT. NT-driven increased synaptic input caused a functional decorrelation of gap junction transmission between lhx6-EGFP neuron pairs. Finally, the synaptic transmission between pyramidal cells and lhx6-EGFP neurons was modulated by addition of NT in favor of stronger inhibition and weaker excitation. These findings demonstrate the existence and functional consequences of an intracortical WM neuron projection, and suggest mechanisms underlying NT-induced promotion of wakefulness.
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Affiliation(s)
- Lovisa Case
- Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden
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9
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Abstract
Recent studies have expanded our understanding of sleep regulation by elucidating multiple neural circuits that promote sleep. In this issue of Neuron, Ma et al. (2019) identify a novel thalamo-amygdalar circuit which uses neurotensin to initiate and sustain NREM sleep.
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Affiliation(s)
- Milan Halgren
- McGovern Institute for Brain Research and Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Michael M Halassa
- McGovern Institute for Brain Research and Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
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10
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Bidirectional and context-dependent changes in theta and gamma oscillatory brain activity in noradrenergic cell-specific Hypocretin/Orexin receptor 1-KO mice. Sci Rep 2018; 8:15474. [PMID: 30341359 PMCID: PMC6195537 DOI: 10.1038/s41598-018-33069-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2018] [Accepted: 09/21/2018] [Indexed: 11/08/2022] Open
Abstract
Noradrenaline (NA) and hypocretins/orexins (HCRT), and their receptors, dynamically modulate the circuits that configure behavioral states, and their associated oscillatory activities. Salient stimuli activate spiking of locus coeruleus noradrenergic (NALC) cells, inducing NA release and brain-wide noradrenergic signalling, thus resetting network activity, and mediating an orienting response. Hypothalamic HCRT neurons provide one of the densest input to NALC cells. To functionally address the HCRT-to-NA connection, we selectively disrupted the Hcrtr1 gene in NA neurons, and analyzed resulting (Hcrtr1Dbh-CKO) mice’, and their control littermates’ electrocortical response in several contexts of enhanced arousal. Under enforced wakefulness (EW), or after cage change (CC), Hcrtr1Dbh-CKO mice exhibited a weakened ability to lower infra-θ frequencies (1–7 Hz), and mount a robust, narrow-bandwidth, high-frequency θ rhythm (~8.5 Hz). A fast-γ (55–80 Hz) response, whose dynamics closely parallelled θ, also diminished, while β/slow-γ activity (15–45 Hz) increased. Furthermore, EW-associated locomotion was lower. Surprisingly, nestbuilding-associated wakefulness, inversely, featured enhanced θ and fast-γ activities. Thus HCRT-to-NA signalling may fine-tune arousal, up in alarming conditions, and down during self-motivated, goal-driven behaviors. Lastly, slow-wave-sleep following EW and CC, but not nestbuilding, was severely deficient in slow-δ waves (0.75–2.25 Hz), suggesting that HCRT-to-NA signalling regulates the slow-δ rebound characterizing sleep after stress-associated arousal.
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11
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Tyree SM, Borniger JC, de Lecea L. Hypocretin as a Hub for Arousal and Motivation. Front Neurol 2018; 9:413. [PMID: 29928253 PMCID: PMC5997825 DOI: 10.3389/fneur.2018.00413] [Citation(s) in RCA: 52] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2018] [Accepted: 05/18/2018] [Indexed: 01/01/2023] Open
Abstract
The lateral hypothalamus is comprised of a heterogeneous mix of neurons that serve to integrate and regulate sleep, feeding, stress, energy balance, reward, and motivated behavior. Within these populations, the hypocretin/orexin neurons are among the most well studied. Here, we provide an overview on how these neurons act as a central hub integrating sensory and physiological information to tune arousal and motivated behavior accordingly. We give special attention to their role in sleep-wake states and conditions of hyper-arousal, as is the case with stress-induced anxiety. We further discuss their roles in feeding, drug-seeking, and sexual behavior, which are all dependent on the motivational state of the animal. We further emphasize the application of powerful techniques, such as optogenetics, chemogenetics, and fiber photometry, to delineate the role these neurons play in lateral hypothalamic functions.
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Affiliation(s)
- Susan M Tyree
- Department of Psychiatry and Behavioral Sciences, Stanford University, Stanford, CA, United States
| | - Jeremy C Borniger
- Department of Psychiatry and Behavioral Sciences, Stanford University, Stanford, CA, United States
| | - Luis de Lecea
- Department of Psychiatry and Behavioral Sciences, Stanford University, Stanford, CA, United States
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12
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Hoerder-Suabedissen A, Hayashi S, Upton L, Nolan Z, Casas-Torremocha D, Grant E, Viswanathan S, Kanold PO, Clasca F, Kim Y, Molnár Z. Subset of Cortical Layer 6b Neurons Selectively Innervates Higher Order Thalamic Nuclei in Mice. Cereb Cortex 2018; 28:1882-1897. [PMID: 29481606 PMCID: PMC6018949 DOI: 10.1093/cercor/bhy036] [Citation(s) in RCA: 78] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2017] [Revised: 01/25/2018] [Accepted: 01/28/2018] [Indexed: 12/16/2022] Open
Abstract
The thalamus receives input from 3 distinct cortical layers, but input from only 2 of these has been well characterized. We therefore investigated whether the third input, derived from layer 6b, is more similar to the projections from layer 6a or layer 5. We studied the projections of a restricted population of deep layer 6 cells ("layer 6b cells") taking advantage of the transgenic mouse Tg(Drd1a-cre)FK164Gsat/Mmucd (Drd1a-Cre), that selectively expresses Cre-recombinase in a subpopulation of layer 6b neurons across the entire cortical mantle. At P8, 18% of layer 6b neurons are labeled with Drd1a-Cre::tdTomato in somatosensory cortex (SS), and some co-express known layer 6b markers. Using Cre-dependent viral tracing, we identified topographical projections to higher order thalamic nuclei. VGluT1+ synapses formed by labeled layer 6b projections were found in posterior thalamic nucleus (Po) but not in the (pre)thalamic reticular nucleus (TRN). The lack of TRN collaterals was confirmed with single-cell tracing from SS. Transmission electron microscopy comparison of terminal varicosities from layer 5 and layer 6b axons in Po showed that L6b varicosities are markedly smaller and simpler than the majority from L5. Our results suggest that L6b projections to the thalamus are distinct from both L5 and L6a projections.
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Affiliation(s)
| | - Shuichi Hayashi
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford OX1 3QX, UK
| | - Louise Upton
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford OX1 3QX, UK
| | - Zachary Nolan
- Neural and Behavioral Sciences, Pennsylvania State University, 500 University Drive, Hershey, PA 17033, USA
| | - Diana Casas-Torremocha
- Department of Anatomy, Histology and Neuroscience, School of Medicine, Autónoma University, Madrid, Spain
| | - Eleanor Grant
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford OX1 3QX, UK
| | - Sarada Viswanathan
- Department of Biology, University of Maryland, 1116 Biosciences Building,College Park, MD 20742, USA
| | - Patrick O Kanold
- Department of Biology, University of Maryland, 1116 Biosciences Building,College Park, MD 20742, USA
| | - Francisco Clasca
- Department of Anatomy, Histology and Neuroscience, School of Medicine, Autónoma University, Madrid, Spain
| | - Yongsoo Kim
- Neural and Behavioral Sciences, Pennsylvania State University, 500 University Drive, Hershey, PA 17033, USA
| | - Zoltán Molnár
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford OX1 3QX, UK
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Elliott JE, De Luche SE, Churchill MJ, Moore C, Cohen AS, Meshul CK, Lim MM. Dietary therapy restores glutamatergic input to orexin/hypocretin neurons after traumatic brain injury in mice. Sleep 2018; 41:4791165. [PMID: 29315422 PMCID: PMC6454530 DOI: 10.1093/sleep/zsx212] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Revised: 10/27/2017] [Indexed: 02/06/2023] Open
Abstract
Study Objectives In previous work, dietary branched-chain amino acid (BCAA) supplementation, precursors to de novo glutamate and γ-aminobutyric acid (GABA) synthesis, restored impaired sleep-wake regulation and orexin neuronal activity following traumatic brain injury (TBI) in mice. TBI was speculated to reduce orexin neuronal activity through decreased regional excitatory (glutamate) and/or increased inhibitory (GABA) input. Therefore, we hypothesized that TBI would decrease synaptic glutamate and/or increase synaptic GABA in nerve terminals contacting orexin neurons, and BCAA supplementation would restore TBI-induced changes in synaptic glutamate and/or GABA. Methods Brain tissue was processed for orexin pre-embed diaminobenzidine labeling and glutamate or GABA postembed immunogold labeling. The density of glutamate and GABA immunogold within presynaptic nerve terminals contacting orexin-positive lateral hypothalamic neurons was quantified using electron microscopy in three groups of mice (n = 8 per group): Sham/noninjured controls, TBI without BCAA supplementation, and TBI with BCAA supplementation (given for 5 days, 48 hr post-TBI). Glutamate and GABA were also quantified within the cortical penumbral region (layer VIb) adjacent to the TBI lesion. Results In the hypothalamus and cortex, TBI decreased relative glutamate density in presynaptic terminals making axodendritic contacts. However, BCAA supplementation only restored relative glutamate density within presynaptic terminals contacting orexin-positive hypothalamic neurons. BCAA supplementation did not change relative glutamate density in presynaptic terminals making axosomatic contacts, or relative GABA density in presynaptic terminals making axosomatic or axodendritic contacts, within either the hypothalamus or cortex. Conclusions These results suggest TBI compromises orexin neuron function via decreased glutamate density and highlight BCAA supplementation as a potential therapy to restore glutamate density to orexin neurons.
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Affiliation(s)
- Jonathan E Elliott
- VA Portland Health Care System, Portland, OR
- Department of Neurology, Oregon Health and Science University, Portland, OR
| | | | | | - Cindy Moore
- VA Portland Health Care System, Portland, OR
| | - Akiva S Cohen
- Department of Anesthesiology and Critical Care Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA
- Department of Anesthesiology, Joseph Stokes Research Institute, Children’s Hospital of Philadelphia, Philadelphia, PA
| | - Charles K Meshul
- VA Portland Health Care System, Portland, OR
- Department of Behavioral Neuroscience and Pathology, Oregon Health and Science University, Portland, OR
| | - Miranda M Lim
- VA Portland Health Care System, Portland, OR
- Department of Neurology, Oregon Health and Science University, Portland, OR
- Department of Medicine and Behavioral Neuroscience, Oregon Institute of Occupational Health Sciences, Oregon Health and Science University, Portland, OR
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Radnikow G, Feldmeyer D. Layer- and Cell Type-Specific Modulation of Excitatory Neuronal Activity in the Neocortex. Front Neuroanat 2018; 12:1. [PMID: 29440997 PMCID: PMC5797542 DOI: 10.3389/fnana.2018.00001] [Citation(s) in RCA: 66] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2017] [Accepted: 01/04/2018] [Indexed: 01/08/2023] Open
Abstract
From an anatomical point of view the neocortex is subdivided into up to six layers depending on the cortical area. This subdivision has been described already by Meynert and Brodmann in the late 19/early 20. century and is mainly based on cytoarchitectonic features such as the size and location of the pyramidal cell bodies. Hence, cortical lamination is originally an anatomical concept based on the distribution of excitatory neuron. However, it has become apparent in recent years that apart from the layer-specific differences in morphological features, many functional properties of neurons are also dependent on cortical layer or cell type. Such functional differences include changes in neuronal excitability and synaptic activity by neuromodulatory transmitters. Many of these neuromodulators are released from axonal afferents from subcortical brain regions while others are released intrinsically. In this review we aim to describe layer- and cell-type specific differences in the effects of neuromodulator receptors in excitatory neurons in layers 2–6 of different cortical areas. We will focus on the neuromodulator systems using adenosine, acetylcholine, dopamine, and orexin/hypocretin as examples because these neuromodulator systems show important differences in receptor type and distribution, mode of release and functional mechanisms and effects. We try to summarize how layer- and cell type-specific neuromodulation may affect synaptic signaling in cortical microcircuits.
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Affiliation(s)
- Gabriele Radnikow
- Research Centre Jülich, Institute of Neuroscience and Medicine, INM-10, Jülich, Germany
| | - Dirk Feldmeyer
- Research Centre Jülich, Institute of Neuroscience and Medicine, INM-10, Jülich, Germany.,Department of Psychiatry, Psychotherapy and Psychosomatics, Medical School, RWTH Aachen University, Aachen, Germany.,Jülich-Aachen Research Alliance - Translational Brain Medicine, Jülich, Germany
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15
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Aracri P, Meneghini S, Coatti A, Amadeo A, Becchetti A. α4β2 ∗ nicotinic receptors stimulate GABA release onto fast-spiking cells in layer V of mouse prefrontal (Fr2) cortex. Neuroscience 2016; 340:48-61. [PMID: 27793780 PMCID: PMC5231322 DOI: 10.1016/j.neuroscience.2016.10.045] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2016] [Revised: 10/08/2016] [Accepted: 10/18/2016] [Indexed: 11/24/2022]
Abstract
α4β2∗ nAChRs stimulate IPSCs in FS interneurons, in layer V of the mouse PFC (Fr2). In P16–P63 mice, nicotine increased both IPSC and mIPSC frequencies. GABAergic terminals adjacent to PV+ cells expressed α4 nAChR. The percentage of FS cells with somatic α4β2∗ currents decreased with age. Hence, nAChRs may be able to induce local circuit disinhibition in Fr2 PFC.
Nicotinic acetylcholine receptors (nAChRs) produce widespread and complex effects on neocortex excitability. We studied how heteromeric nAChRs regulate inhibitory post-synaptic currents (IPSCs), in fast-spiking (FS) layer V neurons of the mouse frontal area 2 (Fr2). In the presence of blockers of ionotropic glutamate receptors, tonic application of 10 μM nicotine augmented the spontaneous IPSC frequency, with minor alterations of amplitudes and kinetics. These effects were studied since the 3rd postnatal week, and persisted throughout the first two months of postnatal life. The action of nicotine was blocked by 1 μM dihydro-β-erythroidine (DHβE; specific for α4∗ nAChRs), but not 10 nM methyllycaconitine (MLA; specific for α7∗ nAChRs). It was mimicked by 10 nM 5-iodo-3-[2(S)-azetidinylmethoxy]pyridine (5-IA; which activates β2∗ nAChRs). Similar results were obtained on miniature IPSCs (mIPSCs). Moreover, during the first five postnatal weeks, approximately 50% of FS cells displayed DHβE-sensitive whole-cell nicotinic currents. This percentage decreased to ∼5% in mice older than P45. By confocal microscopy, the α4 nAChR subunit was immunocytochemically identified on interneurons expressing either parvalbumin (PV), which mainly labels FS cells, or somatostatin (SOM), which labels the other major interneuron population in layer V. GABAergic terminals expressing α4 were observed to be juxtaposed to PV-positive (PV+) cells. A fraction of these terminals displayed PV immunoreactivity. We conclude that α4β2∗ nAChRs can produce sustained regulation of FS cells in Fr2 layer V. The effect presents a presynaptic component, whereas the somatic regulation decreases with age. These mechanisms may contribute to the nAChR-dependent stimulation of excitability during cognitive tasks as well as to the hyperexcitability caused by hyperfunctional heteromeric nAChRs in sleep-related epilepsy.
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Affiliation(s)
- Patrizia Aracri
- Department of Biotechnology and Biosciences, and NeuroMI (Milan Center of Neuroscience), University of Milano-Bicocca, piazza della Scienza 2, Milano 20126, Italy
| | - Simone Meneghini
- Department of Biotechnology and Biosciences, and NeuroMI (Milan Center of Neuroscience), University of Milano-Bicocca, piazza della Scienza 2, Milano 20126, Italy
| | - Aurora Coatti
- Department of Biotechnology and Biosciences, and NeuroMI (Milan Center of Neuroscience), University of Milano-Bicocca, piazza della Scienza 2, Milano 20126, Italy
| | - Alida Amadeo
- Department of Biosciences, University of Milano, Via Celoria 26, Milano 20133, Italy
| | - Andrea Becchetti
- Department of Biotechnology and Biosciences, and NeuroMI (Milan Center of Neuroscience), University of Milano-Bicocca, piazza della Scienza 2, Milano 20126, Italy.
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