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Tzavellas NP, Tsamis KI, Katsenos AP, Davri AS, Simos YV, Nikas IP, Bellos S, Lekkas P, Kanellos FS, Konitsiotis S, Labrakakis C, Vezyraki P, Peschos D. Firing Alterations of Neurons in Alzheimer's Disease: Are They Merely a Consequence of Pathogenesis or a Pivotal Component of Disease Progression? Cells 2024; 13:434. [PMID: 38474398 DOI: 10.3390/cells13050434] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2024] [Revised: 02/26/2024] [Accepted: 02/28/2024] [Indexed: 03/14/2024] Open
Abstract
Alzheimer's disease (AD) is the most prevalent neurodegenerative disorder, yet its underlying causes remain elusive. The conventional perspective on disease pathogenesis attributes alterations in neuronal excitability to molecular changes resulting in synaptic dysfunction. Early hyperexcitability is succeeded by a progressive cessation of electrical activity in neurons, with amyloid beta (Aβ) oligomers and tau protein hyperphosphorylation identified as the initial events leading to hyperactivity. In addition to these key proteins, voltage-gated sodium and potassium channels play a decisive role in the altered electrical properties of neurons in AD. Impaired synaptic function and reduced neuronal plasticity contribute to a vicious cycle, resulting in a reduction in the number of synapses and synaptic proteins, impacting their transportation inside the neuron. An understanding of these neurophysiological alterations, combined with abnormalities in the morphology of brain cells, emerges as a crucial avenue for new treatment investigations. This review aims to delve into the detailed exploration of electrical neuronal alterations observed in different AD models affecting single neurons and neuronal networks.
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Affiliation(s)
- Nikolaos P Tzavellas
- Department of Physiology, Faculty of Medicine, School of Health Sciences, University of Ioannina, 451 10 Ioannina, Greece
| | - Konstantinos I Tsamis
- Department of Physiology, Faculty of Medicine, School of Health Sciences, University of Ioannina, 451 10 Ioannina, Greece
- Department of Neurology, Faculty of Medicine, School of Health Sciences, University Hospital of Ioannina, 455 00 Ioannina, Greece
| | - Andreas P Katsenos
- Department of Physiology, Faculty of Medicine, School of Health Sciences, University of Ioannina, 451 10 Ioannina, Greece
| | - Athena S Davri
- Department of Physiology, Faculty of Medicine, School of Health Sciences, University of Ioannina, 451 10 Ioannina, Greece
| | - Yannis V Simos
- Department of Physiology, Faculty of Medicine, School of Health Sciences, University of Ioannina, 451 10 Ioannina, Greece
| | - Ilias P Nikas
- Medical School, University of Cyprus, 2029 Nicosia, Cyprus
| | - Stefanos Bellos
- Department of Physiology, Faculty of Medicine, School of Health Sciences, University of Ioannina, 451 10 Ioannina, Greece
| | - Panagiotis Lekkas
- Department of Physiology, Faculty of Medicine, School of Health Sciences, University of Ioannina, 451 10 Ioannina, Greece
| | - Foivos S Kanellos
- Department of Physiology, Faculty of Medicine, School of Health Sciences, University of Ioannina, 451 10 Ioannina, Greece
| | - Spyridon Konitsiotis
- Department of Neurology, Faculty of Medicine, School of Health Sciences, University Hospital of Ioannina, 455 00 Ioannina, Greece
| | - Charalampos Labrakakis
- Department of Biological Applications and Technology, University of Ioannina, 451 10 Ioannina, Greece
| | - Patra Vezyraki
- Department of Physiology, Faculty of Medicine, School of Health Sciences, University of Ioannina, 451 10 Ioannina, Greece
| | - Dimitrios Peschos
- Department of Physiology, Faculty of Medicine, School of Health Sciences, University of Ioannina, 451 10 Ioannina, Greece
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2
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Bigelow J, Morrill RJ, Olsen T, Hasenstaub AR. Visual modulation of firing and spectrotemporal receptive fields in mouse auditory cortex. CURRENT RESEARCH IN NEUROBIOLOGY 2022; 3:100040. [DOI: 10.1016/j.crneur.2022.100040] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2022] [Revised: 04/26/2022] [Accepted: 05/06/2022] [Indexed: 10/18/2022] Open
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Vanattou-Saïfoudine N, Han C, Krause R, Vasilaki E, von der Behrens W, Indiveri G. A robust model of Stimulus-Specific Adaptation validated on neuromorphic hardware. Sci Rep 2021; 11:17904. [PMID: 34504155 PMCID: PMC8429557 DOI: 10.1038/s41598-021-97217-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2021] [Accepted: 08/10/2021] [Indexed: 02/08/2023] Open
Abstract
Stimulus-Specific Adaptation (SSA) to repetitive stimulation is a phenomenon that has been observed across many different species and in several brain sensory areas. It has been proposed as a computational mechanism, responsible for separating behaviorally relevant information from the continuous stream of sensory information. Although SSA can be induced and measured reliably in a wide variety of conditions, the network details and intracellular mechanisms giving rise to SSA still remain unclear. Recent computational studies proposed that SSA could be associated with a fast and synchronous neuronal firing phenomenon called Population Spikes (PS). Here, we test this hypothesis using a mean-field rate model and corroborate it using a neuromorphic hardware. As the neuromorphic circuits used in this study operate in real-time with biologically realistic time constants, they can reproduce the same dynamics observed in biological systems, together with the exploration of different connectivity schemes, with complete control of the system parameter settings. Besides, the hardware permits the iteration of multiple experiments over many trials, for extended amounts of time and without losing the networks and individual neural processes being studied. Following this "neuromorphic engineering" approach, we therefore study the PS hypothesis in a biophysically inspired recurrent networks of spiking neurons and evaluate the role of different linear and non-linear dynamic computational primitives such as spike-frequency adaptation or short-term depression (STD). We compare both the theoretical mean-field model of SSA and PS to previously obtained experimental results in the area of novelty detection and observe its behavior on its neuromorphic physical equivalent model. We show how the approach proposed can be extended to other computational neuroscience modelling efforts for understanding high-level phenomena in mechanistic models.
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Affiliation(s)
- Natacha Vanattou-Saïfoudine
- Institute of Neuroinformatics, University of Zurich and ETH Zurich, Zurich, Switzerland.
- Department of Computer Science, University of Sheffield, Sheffield, UK.
| | - Chao Han
- Department of Computer Science, University of Sheffield, Sheffield, UK
| | - Renate Krause
- Institute of Neuroinformatics, University of Zurich and ETH Zurich, Zurich, Switzerland
| | - Eleni Vasilaki
- Department of Computer Science, University of Sheffield, Sheffield, UK
| | | | - Giacomo Indiveri
- Institute of Neuroinformatics, University of Zurich and ETH Zurich, Zurich, Switzerland
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4
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Mathematical framework for place coding in the auditory system. PLoS Comput Biol 2021; 17:e1009251. [PMID: 34339409 PMCID: PMC8360601 DOI: 10.1371/journal.pcbi.1009251] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2020] [Revised: 08/12/2021] [Accepted: 07/06/2021] [Indexed: 11/18/2022] Open
Abstract
In the auditory system, tonotopy is postulated to be the substrate for a place code, where sound frequency is encoded by the location of the neurons that fire during the stimulus. Though conceptually simple, the computations that allow for the representation of intensity and complex sounds are poorly understood. Here, a mathematical framework is developed in order to define clearly the conditions that support a place code. To accommodate both frequency and intensity information, the neural network is described as a space with elements that represent individual neurons and clusters of neurons. A mapping is then constructed from acoustic space to neural space so that frequency and intensity are encoded, respectively, by the location and size of the clusters. Algebraic operations -addition and multiplication- are derived to elucidate the rules for representing, assembling, and modulating multi-frequency sound in networks. The resulting outcomes of these operations are consistent with network simulations as well as with electrophysiological and psychophysical data. The analyses show how both frequency and intensity can be encoded with a purely place code, without the need for rate or temporal coding schemes. The algebraic operations are used to describe loudness summation and suggest a mechanism for the critical band. The mathematical approach complements experimental and computational approaches and provides a foundation for interpreting data and constructing models.
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Staiger JF, Petersen CCH. Neuronal Circuits in Barrel Cortex for Whisker Sensory Perception. Physiol Rev 2020; 101:353-415. [PMID: 32816652 DOI: 10.1152/physrev.00019.2019] [Citation(s) in RCA: 48] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
The array of whiskers on the snout provides rodents with tactile sensory information relating to the size, shape and texture of objects in their immediate environment. Rodents can use their whiskers to detect stimuli, distinguish textures, locate objects and navigate. Important aspects of whisker sensation are thought to result from neuronal computations in the whisker somatosensory cortex (wS1). Each whisker is individually represented in the somatotopic map of wS1 by an anatomical unit named a 'barrel' (hence also called barrel cortex). This allows precise investigation of sensory processing in the context of a well-defined map. Here, we first review the signaling pathways from the whiskers to wS1, and then discuss current understanding of the various types of excitatory and inhibitory neurons present within wS1. Different classes of cells can be defined according to anatomical, electrophysiological and molecular features. The synaptic connectivity of neurons within local wS1 microcircuits, as well as their long-range interactions and the impact of neuromodulators, are beginning to be understood. Recent technological progress has allowed cell-type-specific connectivity to be related to cell-type-specific activity during whisker-related behaviors. An important goal for future research is to obtain a causal and mechanistic understanding of how selected aspects of tactile sensory information are processed by specific types of neurons in the synaptically connected neuronal networks of wS1 and signaled to downstream brain areas, thus contributing to sensory-guided decision-making.
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Affiliation(s)
- Jochen F Staiger
- University Medical Center Göttingen, Institute for Neuroanatomy, Göttingen, Germany; and Laboratory of Sensory Processing, Faculty of Life Sciences, Brain Mind Institute, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
| | - Carl C H Petersen
- University Medical Center Göttingen, Institute for Neuroanatomy, Göttingen, Germany; and Laboratory of Sensory Processing, Faculty of Life Sciences, Brain Mind Institute, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
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6
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Glutamatergic fast-spiking parvalbumin neurons in the lateral hypothalamus: Electrophysiological properties to behavior. Physiol Behav 2020; 221:112912. [PMID: 32289319 DOI: 10.1016/j.physbeh.2020.112912] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2019] [Revised: 02/14/2020] [Accepted: 04/06/2020] [Indexed: 01/10/2023]
Abstract
Throughout the central nervous system, neurons expressing the calcium-binding protein parvalbumin have been typically classified as GABAergic with fast-spiking characteristics. However, new methods that allow systematic characterization of the cytoarchitectural organization, connectivity, activity patterns, neurotransmitter nature, and function of genetically-distinct cell types have revealed populations of parvalbumin-positive neurons that are glutamatergic. Remarkably, such findings challenge longstanding concepts that fast-spiking neurons are exclusively GABAergic, suggesting conservation of the fast-spiking phenotype across at least two neurotransmitter systems. This review focuses on the recent advancements that have begun to reveal the functional roles of lateral hypothalamic parvalbumin-positive neurons in regulating behaviors essential for survival.
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7
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Wen TH, Afroz S, Reinhard SM, Palacios AR, Tapia K, Binder DK, Razak KA, Ethell IM. Genetic Reduction of Matrix Metalloproteinase-9 Promotes Formation of Perineuronal Nets Around Parvalbumin-Expressing Interneurons and Normalizes Auditory Cortex Responses in Developing Fmr1 Knock-Out Mice. Cereb Cortex 2019; 28:3951-3964. [PMID: 29040407 DOI: 10.1093/cercor/bhx258] [Citation(s) in RCA: 94] [Impact Index Per Article: 18.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2017] [Indexed: 01/08/2023] Open
Abstract
Abnormal sensory responses associated with Fragile X Syndrome (FXS) and autism spectrum disorders include hypersensitivity and impaired habituation to repeated stimuli. Similar sensory deficits are also observed in adult Fmr1 knock-out (KO) mice and are reversed by genetic deletion of Matrix Metalloproteinase-9 (MMP-9) through yet unknown mechanisms. Here we present new evidence that impaired development of parvalbumin (PV)-expressing inhibitory interneurons may underlie hyper-responsiveness in auditory cortex of Fmr1 KO mice via MMP-9-dependent regulation of perineuronal nets (PNNs). First, we found that PV cell development and PNN formation around GABAergic interneurons were impaired in developing auditory cortex of Fmr1 KO mice. Second, MMP-9 levels were elevated in P12-P18 auditory cortex of Fmr1 KO mice and genetic reduction of MMP-9 to WT levels restored the formation of PNNs around PV cells. Third, in vivo single-unit recordings from auditory cortex neurons showed enhanced spontaneous and sound-driven responses in developing Fmr1 KO mice, which were normalized following genetic reduction of MMP-9. These findings indicate that elevated MMP-9 levels contribute to the development of sensory hypersensitivity by influencing formation of PNNs around PV interneurons suggesting MMP-9 as a new therapeutic target to reduce sensory deficits in FXS and potentially other autism spectrum disorders.
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Affiliation(s)
- Teresa H Wen
- Division of Biomedical Sciences, University of California Riverside School of Medicine, Riverside, CA, USA.,Neuroscience Graduate Program, University of California Riverside, Riverside, CA, USA
| | - Sonia Afroz
- Division of Biomedical Sciences, University of California Riverside School of Medicine, Riverside, CA, USA
| | - Sarah M Reinhard
- Psychology Department and Psychology Graduate Program, University of California Riverside, Riverside, CA, USA
| | - Arnold R Palacios
- Division of Biomedical Sciences, University of California Riverside School of Medicine, Riverside, CA, USA
| | - Kendal Tapia
- Division of Biomedical Sciences, University of California Riverside School of Medicine, Riverside, CA, USA
| | - Devin K Binder
- Division of Biomedical Sciences, University of California Riverside School of Medicine, Riverside, CA, USA
| | - Khaleel A Razak
- Neuroscience Graduate Program, University of California Riverside, Riverside, CA, USA.,Psychology Department and Psychology Graduate Program, University of California Riverside, Riverside, CA, USA
| | - Iryna M Ethell
- Division of Biomedical Sciences, University of California Riverside School of Medicine, Riverside, CA, USA.,Neuroscience Graduate Program, University of California Riverside, Riverside, CA, USA
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8
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Abstract
Sleep spindles are burstlike signals in the electroencephalogram (EEG) of the sleeping mammalian brain and electrical surface correlates of neuronal oscillations in thalamus. As one of the most inheritable sleep EEG signatures, sleep spindles probably reflect the strength and malleability of thalamocortical circuits that underlie individual cognitive profiles. We review the characteristics, organization, regulation, and origins of sleep spindles and their implication in non-rapid-eye-movement sleep (NREMS) and its functions, focusing on human and rodent. Spatially, sleep spindle-related neuronal activity appears on scales ranging from small thalamic circuits to functional cortical areas, and generates a cortical state favoring intracortical plasticity while limiting cortical output. Temporally, sleep spindles are discrete events, part of a continuous power band, and elements grouped on an infraslow time scale over which NREMS alternates between continuity and fragility. We synthesize diverse and seemingly unlinked functions of sleep spindles for sleep architecture, sensory processing, synaptic plasticity, memory formation, and cognitive abilities into a unifying sleep spindle concept, according to which sleep spindles 1) generate neural conditions of large-scale functional connectivity and plasticity that outlast their appearance as discrete EEG events, 2) appear preferentially in thalamic circuits engaged in learning and attention-based experience during wakefulness, and 3) enable a selective reactivation and routing of wake-instated neuronal traces between brain areas such as hippocampus and cortex. Their fine spatiotemporal organization reflects NREMS as a physiological state coordinated over brain and body and may indicate, if not anticipate and ultimately differentiate, pathologies in sleep and neurodevelopmental, -degenerative, and -psychiatric conditions.
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Affiliation(s)
- Laura M J Fernandez
- Department of Fundamental Neurosciences, University of Lausanne, Lausanne, Switzerland
| | - Anita Lüthi
- Department of Fundamental Neurosciences, University of Lausanne, Lausanne, Switzerland
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9
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Rock C, Zurita H, Lebby S, Wilson CJ, Apicella AJ. Cortical Circuits of Callosal GABAergic Neurons. Cereb Cortex 2019; 28:1154-1167. [PMID: 28174907 DOI: 10.1093/cercor/bhx025] [Citation(s) in RCA: 43] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2016] [Accepted: 01/18/2017] [Indexed: 12/24/2022] Open
Abstract
Anatomical studies have shown that the majority of callosal axons are glutamatergic. However, a small proportion of callosal axons are also immunoreactive for glutamic acid decarboxylase, an enzyme required for gamma-aminobutyric acid (GABA) synthesis and a specific marker for GABAergic neurons. Here, we test the hypothesis that corticocortical parvalbumin-expressing (CC-Parv) neurons connect the two hemispheres of multiple cortical areas, project through the corpus callosum, and are a functional part of the local cortical circuit. Our investigation of this hypothesis takes advantage of viral tracing and optogenetics to determine the anatomical and electrophysiological properties of CC-Parv neurons of the mouse auditory, visual, and motor cortices. We found a direct inhibitory pathway made up of parvalbumin-expressing (Parv) neurons which connects corresponding cortical areas (CC-Parv neurons → contralateral cortex). Like other Parv cortical neurons, these neurons provide local inhibition onto nearby pyramidal neurons and receive thalamocortical input. These results demonstrate a previously unknown long-range inhibitory circuit arising from a genetically defined type of GABAergic neuron that is engaged in interhemispheric communication.
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Affiliation(s)
- Crystal Rock
- Department of Biology, Neurosciences Institute, University of Texas at San Antonio, Biosciences Building 1.03.26, One UTSA Circle, San Antonio, TX 78249, USA
| | - Hector Zurita
- Department of Biology, Neurosciences Institute, University of Texas at San Antonio, Biosciences Building 1.03.26, One UTSA Circle, San Antonio, TX 78249, USA
| | - Sharmon Lebby
- Department of Biology, Neurosciences Institute, University of Texas at San Antonio, Biosciences Building 1.03.26, One UTSA Circle, San Antonio, TX 78249, USA
| | - Charles J Wilson
- Department of Biology, Neurosciences Institute, University of Texas at San Antonio, Biosciences Building 1.03.26, One UTSA Circle, San Antonio, TX 78249, USA
| | - Alfonso Junior Apicella
- Department of Biology, Neurosciences Institute, University of Texas at San Antonio, Biosciences Building 1.03.26, One UTSA Circle, San Antonio, TX 78249, USA
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Sedigh-Sarvestani M, Palmer LA, Contreras D. Thalamocortical synapses in the cat visual system in vivo are weak and unreliable. eLife 2019; 8:41925. [PMID: 31032799 PMCID: PMC6506206 DOI: 10.7554/elife.41925] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2018] [Accepted: 04/27/2019] [Indexed: 01/05/2023] Open
Abstract
The thalamocortical synapse of the visual system has been central to our understanding of sensory computations in the cortex. Although we have a fair understanding of the functional properties of the pre and post-synaptic populations, little is known about their synaptic properties, particularly in vivo. We used simultaneous recordings in LGN and V1 in cat in vivo to characterize the dynamic properties of thalamocortical synaptic transmission in monosynaptically connected LGN-V1 neurons. We found that thalamocortical synapses in vivo are unreliable, highly variable and exhibit short-term plasticity. Using biologically constrained models, we found that variable and unreliable synapses serve to increase cortical firing by means of increasing membrane fluctuations, similar to high conductance states. Thus, synaptic variability and unreliability, rather than acting as system noise, do serve a computational function. Our characterization of LGN-V1 synaptic properties constrains existing mathematical models, and mechanistic hypotheses, of a fundamental circuit in computational neuroscience.
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Affiliation(s)
- Madineh Sedigh-Sarvestani
- Department of Neuroscience, School of Medicine, University of Pennsylvania, Philadelphia, United States
| | - Larry A Palmer
- Department of Neuroscience, School of Medicine, University of Pennsylvania, Philadelphia, United States
| | - Diego Contreras
- Department of Neuroscience, School of Medicine, University of Pennsylvania, Philadelphia, United States
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11
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Ueno H, Suemitsu S, Murakami S, Kitamura N, Wani K, Matsumoto Y, Okamoto M, Ishihara T. Layer-specific expression of extracellular matrix molecules in the mouse somatosensory and piriform cortices. IBRO Rep 2018; 6:1-17. [PMID: 30582064 PMCID: PMC6293036 DOI: 10.1016/j.ibror.2018.11.006] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2018] [Accepted: 11/24/2018] [Indexed: 02/04/2023] Open
Abstract
In the developing central nervous system (CNS), extracellular matrix (ECM) molecules have regulating roles such as in brain development, neural-circuit maturation, and synaptic-function control. However, excluding the perineuronal net (PNN) area, the distribution, constituent elements, and expression level of granular ECM molecules (diffuse ECM) present in the mature CNS remain unclear. Diffuse ECM molecules in the CNS share the components of PNNs and are likely functional. As cortical functions are greatly region-dependent, we hypothesized that ECM molecules would differ in distribution, expression level, and components in a region- and layer-dependent manner. We examined the layer-specific expression of several chondroitin sulfate proteoglycans (aggrecan, neurocan, and brevican), tenascin-R, Wisteria floribunda agglutinin (WFA)-positive molecules, hyaluronic acid, and link protein in the somatosensory and piriform cortices of mature mice. Furthermore, we investigated expression changes in WFA-positive molecules due to aging. In the somatosensory cortex, PNN density was particularly high at layer 4 (L4), but not all diffuse ECM molecules were highly expressed at L4 compared to the other layers. There was almost no change in tenascin-R and hyaluronic acid in any somatosensory-cortex layer. Neurocan showed high expression in L1 of the somatosensory cortex. In the piriform cortex, many ECM molecules showed higher expression in L1 than in the other layers. However, hyaluronic acid showed high expression in deep layers. Here, we clarified that ECM molecules differ in constituent elements and expression in a region- and layer-dependent manner. Region-specific expression of ECM molecules is possibly related to functions such as region-specific plasticity and vulnerability.
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Key Words
- CNS, central nervous system
- CSPG, chondroitin sulfate proteoglycans
- ChABC, chondroitinase ABC
- ECM, extracellular cellular matrix
- Extracellular matrix
- HA, hyaluronic acid
- HABP, hyaluronic acid binding protein
- Hapln1, hyaluronan and proteoglycan link protein 1
- PNN, perineuronal ntes
- Perineuronal nets
- Piriform cortex
- Proteoglycans
- Somatosensory cortex
- WFA, Wisteria floribunda agglutinin
- Wisteria floribunda
- a.u., arbitrary units
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Affiliation(s)
- Hiroshi Ueno
- Department of Medical Technology, Kawasaki University of Medical Welfare, 288, Matsushima, Kurashiki, Okayama, 701-0193, Japan
| | - Shunsuke Suemitsu
- Department of Psychiatry, Kawasaki Medical School, Kurashiki, 701-0192, Japan
| | - Shinji Murakami
- Department of Psychiatry, Kawasaki Medical School, Kurashiki, 701-0192, Japan
| | - Naoya Kitamura
- Department of Psychiatry, Kawasaki Medical School, Kurashiki, 701-0192, Japan
| | - Kenta Wani
- Department of Psychiatry, Kawasaki Medical School, Kurashiki, 701-0192, Japan
| | - Yosuke Matsumoto
- Department of Neuropsychiatry, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Okayama, 700-8558, Japan
| | - Motoi Okamoto
- Department of Medical Technology, Graduate School of Health Sciences, Okayama University, Okayama, 700-8558, Japan
| | - Takeshi Ishihara
- Department of Psychiatry, Kawasaki Medical School, Kurashiki, 701-0192, Japan
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12
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Audette NJ, Urban-Ciecko J, Matsushita M, Barth AL. POm Thalamocortical Input Drives Layer-Specific Microcircuits in Somatosensory Cortex. Cereb Cortex 2018; 28:1312-1328. [PMID: 28334225 PMCID: PMC6093433 DOI: 10.1093/cercor/bhx044] [Citation(s) in RCA: 68] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2016] [Revised: 02/03/2017] [Indexed: 12/11/2022] Open
Abstract
Higher-order thalamic nuclei, such as the posterior medial nucleus (POm) in the somatosensory system or the pulvinar in the visual system, densely innervate the cortex and can influence perception and plasticity. To systematically evaluate how higher-order thalamic nuclei can drive cortical circuits, we investigated cell-type selective responses to POm stimulation in mouse primary somatosensory (barrel) cortex, using genetically targeted whole-cell recordings in acute brain slices. We find that ChR2-evoked thalamic input selectively targets specific cell types in the neocortex, revealing layer-specific modules for the summation and processing of POm input. Evoked activity in pyramidal neurons from deep layers is fast and synchronized by rapid feedforward inhibition from GABAergic parvalbumin-expressing neurons, and activity in superficial layers is weaker and prolonged, facilitated by slow inhibition from GABAergic neurons expressing the 5HT3a receptor. Somatostatin-expressing GABAergic neurons do not receive direct input in either layer and their spontaneous activity is suppressed during POm stimulation. This novel pattern of weak, delayed, thalamus-evoked inhibition in layer 2 suggests a longer integration window for incoming sensory information and may facilitate stimulus detection and plasticity in superficial pyramidal neurons.
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Affiliation(s)
- Nicholas J Audette
- Department of Biological Sciences and Center for the Neural Basis of Cognition, Carnegie Mellon University, 4400 Fifth Avenue, Pittsburgh, PA, USA
| | - Joanna Urban-Ciecko
- Department of Biological Sciences and Center for the Neural Basis of Cognition, Carnegie Mellon University, 4400 Fifth Avenue, Pittsburgh, PA, USA
| | - Megumi Matsushita
- Department of Biological Sciences and Center for the Neural Basis of Cognition, Carnegie Mellon University, 4400 Fifth Avenue, Pittsburgh, PA, USA
| | - Alison L Barth
- Department of Biological Sciences and Center for the Neural Basis of Cognition, Carnegie Mellon University, 4400 Fifth Avenue, Pittsburgh, PA, USA
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13
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Abstract
Cortical networks are composed of glutamatergic excitatory projection neurons and local GABAergic inhibitory interneurons that gate signal flow and sculpt network dynamics. Although they represent a minority of the total neocortical neuronal population, GABAergic interneurons are highly heterogeneous, forming functional classes based on their morphological, electrophysiological, and molecular features, as well as connectivity and in vivo patterns of activity. Here we review our current understanding of neocortical interneuron diversity and the properties that distinguish cell types. We then discuss how the involvement of multiple cell types, each with a specific set of cellular properties, plays a crucial role in diversifying and increasing the computational power of a relatively small number of simple circuit motifs forming cortical networks. We illustrate how recent advances in the field have shed light onto the mechanisms by which GABAergic inhibition contributes to network operations.
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14
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Jercog D, Roxin A, Barthó P, Luczak A, Compte A, de la Rocha J. UP-DOWN cortical dynamics reflect state transitions in a bistable network. eLife 2017; 6:22425. [PMID: 28826485 PMCID: PMC5582872 DOI: 10.7554/elife.22425] [Citation(s) in RCA: 75] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2016] [Accepted: 07/21/2017] [Indexed: 11/21/2022] Open
Abstract
In the idling brain, neuronal circuits transition between periods of sustained firing (UP state) and quiescence (DOWN state), a pattern the mechanisms of which remain unclear. Here we analyzed spontaneous cortical population activity from anesthetized rats and found that UP and DOWN durations were highly variable and that population rates showed no significant decay during UP periods. We built a network rate model with excitatory (E) and inhibitory (I) populations exhibiting a novel bistable regime between a quiescent and an inhibition-stabilized state of arbitrarily low rate. Fluctuations triggered state transitions, while adaptation in E cells paradoxically caused a marginal decay of E-rate but a marked decay of I-rate in UP periods, a prediction that we validated experimentally. A spiking network implementation further predicted that DOWN-to-UP transitions must be caused by synchronous high-amplitude events. Our findings provide evidence of bistable cortical networks that exhibit non-rhythmic state transitions when the brain rests.
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Affiliation(s)
- Daniel Jercog
- Institut d'Investigacions Biomèdiques August Pi i Sunyer, Barcelona, Spain
| | - Alex Roxin
- Centre de Recerca Matemàtica, Bellaterra, Spain
| | - Peter Barthó
- MTA TTK NAP B Research Group of Sleep Oscillations, Budapest, Hungary
| | - Artur Luczak
- Canadian Center for Behavioural Neuroscience, University of Lethbridge, Lethbridge, Canada
| | - Albert Compte
- Institut d'Investigacions Biomèdiques August Pi i Sunyer, Barcelona, Spain
| | - Jaime de la Rocha
- Institut d'Investigacions Biomèdiques August Pi i Sunyer, Barcelona, Spain
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15
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Intracellular, In Vivo, Dynamics of Thalamocortical Synapses in Visual Cortex. J Neurosci 2017; 37:5250-5262. [PMID: 28438969 DOI: 10.1523/jneurosci.3370-16.2017] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2016] [Revised: 02/24/2017] [Accepted: 04/01/2017] [Indexed: 11/21/2022] Open
Abstract
Seminal studies of the thalamocortical circuit in the visual system of the cat have been central to our understanding of sensory encoding. However, thalamocortical synaptic properties remain poorly understood. We used paired recordings, in the lateral geniculate nucleus (LGN) and primary visual cortex (V1), to provide the first in vivo characterization of sensory-driven thalamocortical potentials in V1. The amplitudes of EPSPs we characterized were smaller than those previously reported in vitro Consistent with prior findings, connected LGN-V1 pairs were only found when their receptive fields (RFs) overlapped, and the probability of connection increased steeply with degree of RF overlap and response similarity. However, surprisingly, we found no relationship between EPSP amplitudes and the similarity of RFs or responses, suggesting different connectivity models for intracortical and thalamocortical circuits. Putative excitatory regular-spiking (RS) and inhibitory fast-spiking (FS) V1 cells had similar EPSP characteristics, showing that in the visual system, feedforward excitation and inhibition are driven with equal strength by the thalamus. Similar to observations in the somatosensory cortex, FS V1 cells received less specific input from LGN. Finally, orientation tuning in V1 was not inherited from single presynaptic LGN cells, suggesting that it must emerge exclusively from the combined input of all presynaptic LGN cells. Our results help to decipher early visual encoding circuits and have immediate utility in providing physiological constraints to computational models of the visual system.SIGNIFICANCE STATEMENT To understand how the brain encodes the visual environment, we must understand the transfer of visual signals between various regions of the brain. Therefore, understanding synaptic dynamics is critical to our understanding of sensory encoding. This study provides the first characterization of visually evoked synaptic potentials between the visual thalamus and visual cortex in an intact animal. To record these potentials, we simultaneously recorded the extracellular potential of presynaptic thalamic cells and the intracellular potential of postsynaptic cortical cells in input layers of primary visual cortex. Our characterization of synaptic potentials in vivo disagreed with prior findings in vitro This study will increase our understanding of thalamocortical circuits and will improve computational models of visual encoding.
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16
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Yarden TS, Nelken I. Stimulus-specific adaptation in a recurrent network model of primary auditory cortex. PLoS Comput Biol 2017; 13:e1005437. [PMID: 28288158 PMCID: PMC5367837 DOI: 10.1371/journal.pcbi.1005437] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2016] [Revised: 03/27/2017] [Accepted: 03/02/2017] [Indexed: 12/02/2022] Open
Abstract
Stimulus-specific adaptation (SSA) occurs when neurons decrease their responses to frequently-presented (standard) stimuli but not, or not as much, to other, rare (deviant) stimuli. SSA is present in all mammalian species in which it has been tested as well as in birds. SSA confers short-term memory to neuronal responses, and may lie upstream of the generation of mismatch negativity (MMN), an important human event-related potential. Previously published models of SSA mostly rely on synaptic depression of the feedforward, thalamocortical input. Here we study SSA in a recurrent neural network model of primary auditory cortex. When the recurrent, intracortical synapses display synaptic depression, the network generates population spikes (PSs). SSA occurs in this network when deviants elicit a PS but standards do not, and we demarcate the regions in parameter space that allow SSA. While SSA based on PSs does not require feedforward depression, we identify feedforward depression as a mechanism for expanding the range of parameters that support SSA. We provide predictions for experiments that could help differentiate between SSA due to synaptic depression of feedforward connections and SSA due to synaptic depression of recurrent connections. Similar to experimental data, the magnitude of SSA in the model depends on the frequency difference between deviant and standard, probability of the deviant, inter-stimulus interval and input amplitude. In contrast to models based on feedforward depression, our model shows true deviance sensitivity as found in experiments.
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Affiliation(s)
- Tohar S. Yarden
- Department of Neurobiology, the Alexander Silberman Institute of Life Sciences and the Edmond and Lily Safra Center for Brain Sciences, Hebrew University, Jerusalem, Israel
| | - Israel Nelken
- Department of Neurobiology, the Alexander Silberman Institute of Life Sciences and the Edmond and Lily Safra Center for Brain Sciences, Hebrew University, Jerusalem, Israel
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17
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An Ultrastructural Study of the Thalamic Input to Layer 4 of Primary Motor and Primary Somatosensory Cortex in the Mouse. J Neurosci 2017; 37:2435-2448. [PMID: 28137974 DOI: 10.1523/jneurosci.2557-16.2017] [Citation(s) in RCA: 72] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2016] [Revised: 01/17/2017] [Accepted: 01/19/2017] [Indexed: 12/22/2022] Open
Abstract
The traditional classification of primary motor cortex (M1) as an agranular area has been challenged recently when a functional layer 4 (L4) was reported in M1. L4 is the principal target for thalamic input in sensory areas, which raises the question of how thalamocortical synapses formed in M1 in the mouse compare with those in neighboring sensory cortex (S1). We identified thalamic boutons by their immunoreactivity for the vesicular glutamate transporter 2 (VGluT2) and performed unbiased disector counts from electron micrographs. We discovered that the thalamus contributed proportionately only half as many synapses to the local circuitry of L4 in M1 compared with S1. Furthermore, thalamic boutons in M1 targeted spiny dendrites exclusively, whereas ∼9% of synapses were formed with dendrites of smooth neurons in S1. VGluT2+ boutons in M1 were smaller and formed fewer synapses per bouton on average (1.3 vs 2.1) than those in S1, but VGluT2+ synapses in M1 were larger than in S1 (median postsynaptic density areas of 0.064 μm2 vs 0.042 μm2). In M1 and S1, thalamic synapses formed only a small fraction (12.1% and 17.2%, respectively) of all of the asymmetric synapses in L4. The functional role of the thalamic input to L4 in M1 has largely been neglected, but our data suggest that, as in S1, the thalamic input is amplified by the recurrent excitatory connections of the L4 circuits. The lack of direct thalamic input to inhibitory neurons in M1 may indicate temporal differences in the inhibitory gating in L4 of M1 versus S1.SIGNIFICANCE STATEMENT Classical interpretations of the function of primary motor cortex (M1) emphasize its lack of the granular layer 4 (L4) typical of sensory cortices. However, we show here that, like sensory cortex (S1), mouse M1 also has the canonical circuit motif of a core thalamic input to the middle cortical layer and that thalamocortical synapses form a small fraction (M1: 12%; S1: 17%) of all asymmetric synapses in L4 of both areas. Amplification of thalamic input by recurrent local circuits is thus likely to be a significant mechanism in both areas. Unlike M1, where thalamocortical boutons typically form a single synapse, thalamocortical boutons in S1 usually formed multiple synapses, which means they can be identified with high probability in the electron microscope without specific labeling.
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18
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Fukuda T. Structural organization of the dendritic reticulum linked by gap junctions in layer 4 of the visual cortex. Neuroscience 2017; 340:76-90. [DOI: 10.1016/j.neuroscience.2016.10.050] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2016] [Revised: 10/07/2016] [Accepted: 10/20/2016] [Indexed: 11/16/2022]
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19
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Kato HK, Gillet SN, Isaacson JS. Flexible Sensory Representations in Auditory Cortex Driven by Behavioral Relevance. Neuron 2015; 88:1027-1039. [PMID: 26586181 DOI: 10.1016/j.neuron.2015.10.024] [Citation(s) in RCA: 142] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2015] [Revised: 09/10/2015] [Accepted: 10/13/2015] [Indexed: 11/28/2022]
Abstract
Animals require the ability to ignore sensory stimuli that have no consequence yet respond to the same stimuli when they become useful. However, the brain circuits that govern this flexibility in sensory processing are not well understood. Here we show in mouse primary auditory cortex (A1) that daily passive sound exposure causes a long-lasting reduction in representations of the experienced sound by layer 2/3 pyramidal cells. This habituation arises locally in A1 and involves an enhancement in inhibition and selective upregulation in the activity of somatostatin-expressing inhibitory neurons (SOM cells). Furthermore, when mice engage in sound-guided behavior, pyramidal cell excitatory responses to habituated sounds are enhanced, whereas SOM cell responses are diminished. Together, our results demonstrate the bidirectional modulation of A1 sensory representations and suggest that SOM cells gate cortical information flow based on the behavioral relevance of the stimulus.
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Affiliation(s)
- Hiroyuki K Kato
- Center for Neural Circuits and Behavior and Department of Neurosciences, University of California, San Diego, La Jolla, CA 92093, USA.
| | - Shea N Gillet
- Center for Neural Circuits and Behavior and Department of Neurosciences, University of California, San Diego, La Jolla, CA 92093, USA
| | - Jeffry S Isaacson
- Center for Neural Circuits and Behavior and Department of Neurosciences, University of California, San Diego, La Jolla, CA 92093, USA
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20
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Parvalbumin-Positive Inhibitory Interneurons Oppose Propagation But Favor Generation of Focal Epileptiform Activity. J Neurosci 2015; 35:9544-57. [PMID: 26134638 DOI: 10.1523/jneurosci.5117-14.2015] [Citation(s) in RCA: 100] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Parvalbumin (Pv)-positive inhibitory interneurons effectively control network excitability, and their optogenetic activation has been reported to block epileptic seizures. An intense activity in GABAergic interneurons, including Pv interneurons, before seizures has been described in different experimental models of epilepsy, raising the hypothesis that an increased GABAergic inhibitory signal may, under certain conditions, initiate seizures. It is therefore unclear whether the activity of Pv interneurons enhances or opposes epileptiform activities. Here we use a mouse cortical slice model of focal epilepsy in which the epileptogenic focus can be identified and the role of Pv interneurons in the generation and propagation of seizure-like ictal events is accurately analyzed by a combination of optogenetic, electrophysiological, and imaging techniques. We found that a selective activation of Pv interneurons at the focus failed to block ictal generation and induced postinhibitory rebound spiking in pyramidal neurons, enhancing neuronal synchrony and promoting ictal generation. In contrast, a selective activation of Pv interneurons distant from the focus blocked ictal propagation and shortened ictal duration at the focus. We revealed that the reduced ictal duration was a direct consequence of the ictal propagation block, probably by preventing newly generated afterdischarges to travel backwards to the original focus of ictal initiation. Similar results were obtained upon individual Pv interneuron activation by intracellular depolarizing current pulses. The functional dichotomy of Pv interneurons here described opens new perspectives to our understanding of how local inhibitory circuits govern generation and spread of focal epileptiform activities.
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21
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Kaiser T, Ting JT, Monteiro P, Feng G. Transgenic labeling of parvalbumin-expressing neurons with tdTomato. Neuroscience 2015; 321:236-245. [PMID: 26318335 DOI: 10.1016/j.neuroscience.2015.08.036] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2015] [Revised: 08/08/2015] [Accepted: 08/18/2015] [Indexed: 12/22/2022]
Abstract
Parvalbumin (PVALB)-expressing fast-spiking interneurons subserve important roles in many brain regions by modulating circuit function and dysfunction of these neurons is strongly implicated in neuropsychiatric disorders including schizophrenia and autism. To facilitate the study of PVALB neuron function we need to be able to identify PVALB neurons in vivo. We have generated a bacterial artificial chromosome (BAC) transgenic mouse line expressing the red fluorophore tdTomato under the control of endogenous regulatory elements of the Pvalb gene locus (JAX # 027395). We show that the tdTomato transgene is faithfully expressed relative to endogenous PVALB expression throughout the brain. Furthermore, targeted patch clamp recordings confirm that the labeled populations in neocortex, striatum, and hippocampus are fast-spiking interneurons based on intrinsic properties. This new transgenic mouse line provides a useful tool to study PVALB neuron function in the normal brain as well as in mouse models of psychiatric disease.
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Affiliation(s)
- T Kaiser
- McGovern Institute for Brain Research at MIT, Cambridge, MA 02139, USA; Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - J T Ting
- McGovern Institute for Brain Research at MIT, Cambridge, MA 02139, USA; Human Cell Types Department, Allen Institute for Brain Science, 551 North 34th Street, Seattle, WA 98103, USA
| | - P Monteiro
- McGovern Institute for Brain Research at MIT, Cambridge, MA 02139, USA; Stanley Center for Psychiatric Research, Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA; PhD Program in Experimental Biology and Biomedicine (PDBEB), Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal
| | - G Feng
- McGovern Institute for Brain Research at MIT, Cambridge, MA 02139, USA; Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; Stanley Center for Psychiatric Research, Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA.
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22
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The mediodorsal thalamus drives feedforward inhibition in the anterior cingulate cortex via parvalbumin interneurons. J Neurosci 2015; 35:5743-53. [PMID: 25855185 DOI: 10.1523/jneurosci.4565-14.2015] [Citation(s) in RCA: 144] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Although the medial prefrontal cortex (mPFC) is classically defined by its reciprocal connections with the mediodorsal thalamic nucleus (MD), the nature of information transfer between MD and mPFC is poorly understood. In sensory thalamocortical pathways, thalamic recruitment of feedforward inhibition mediated by fast-spiking, putative parvalbumin-expressing (PV) interneurons is a key feature that enables cortical neurons to represent sensory stimuli with high temporal fidelity. Whether a similar circuit mechanism is in place for the projection from the MD (a higher-order thalamic nucleus that does not receive direct input from the periphery) to the mPFC is unknown. Here we show in mice that inputs from the MD drive disynaptic feedforward inhibition in the dorsal anterior cingulate cortex (dACC) subregion of the mPFC. In particular, we demonstrate that axons arising from MD neurons directly synapse onto and excite PV interneurons that in turn mediate feedforward inhibition of pyramidal neurons in layer 3 of the dACC. This feedforward inhibition in the dACC limits the time window during which pyramidal neurons integrate excitatory synaptic inputs and fire action potentials, but in a manner that allows for greater flexibility than in sensory cortex. These findings provide a foundation for understanding the role of MD-PFC circuit function in cognition.
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23
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Ji XY, Zingg B, Mesik L, Xiao Z, Zhang LI, Tao HW. Thalamocortical Innervation Pattern in Mouse Auditory and Visual Cortex: Laminar and Cell-Type Specificity. Cereb Cortex 2015; 26:2612-25. [PMID: 25979090 DOI: 10.1093/cercor/bhv099] [Citation(s) in RCA: 106] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Despite many previous studies, the functional innervation pattern of thalamic axons and their target specificity remains to be investigated thoroughly. Here, in primary auditory cortical slices, we examined thalamic innervation patterns for excitatory and different types of inhibitory neurons across laminae, by optogenetically stimulating axons from the medial geniculate body. We found that excitatory cells and parvalbumin (PV)-expressing inhibitory neurons across layer 2/3 (L2/3) to L6 are directly innervated by thalamic projections, with the strongest innervation occurring in L4. The innervation of PV neurons is stronger than that of excitatory neurons in the same layer, with a relatively constant ratio between their innervation strengths across layers. For somatostatin and vasoactive intestinal peptide inhibitory neurons, essentially only L4 neurons were innervated by thalamic axons and the innervation was much weaker compared with excitatory and PV cells. In addition, more than half of inhibitory neurons in L1 were innervated, relatively strongly, by thalamic axons. Similar innervation patterns were also observed in the primary visual cortex. Thus, thalamic information can be processed independently and differentially by different cortical layers, in addition to the generally thought hierarchical processing starting from L4. This parallel processing is likely shaped by feedforward inhibition from PV neurons in each individual lamina, and may extend the computation power of sensory cortices.
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Affiliation(s)
- Xu-Ying Ji
- Department of Physiology, School of Basic Medical Sciences, Southern Medical University, Guangzhou 510515, China Zilkha Neurogenetic Institute
| | - Brian Zingg
- Zilkha Neurogenetic Institute Neuroscience Graduate Program, Keck School of Medicine, University of Southern California, Los Angeles, CA 90089, USA
| | - Lukas Mesik
- Zilkha Neurogenetic Institute Neuroscience Graduate Program, Keck School of Medicine, University of Southern California, Los Angeles, CA 90089, USA
| | - Zhongju Xiao
- Department of Physiology, School of Basic Medical Sciences, Southern Medical University, Guangzhou 510515, China
| | - Li I Zhang
- Zilkha Neurogenetic Institute Department of Biophysics and Physiology
| | - Huizhong W Tao
- Zilkha Neurogenetic Institute Department of Cell and Neurobiology
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24
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Bendor D. The role of inhibition in a computational model of an auditory cortical neuron during the encoding of temporal information. PLoS Comput Biol 2015; 11:e1004197. [PMID: 25879843 PMCID: PMC4400160 DOI: 10.1371/journal.pcbi.1004197] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2014] [Accepted: 02/12/2015] [Indexed: 11/19/2022] Open
Abstract
In auditory cortex, temporal information within a sound is represented by two complementary neural codes: a temporal representation based on stimulus-locked firing and a rate representation, where discharge rate co-varies with the timing between acoustic events but lacks a stimulus-synchronized response. Using a computational neuronal model, we find that stimulus-locked responses are generated when sound-evoked excitation is combined with strong, delayed inhibition. In contrast to this, a non-synchronized rate representation is generated when the net excitation evoked by the sound is weak, which occurs when excitation is coincident and balanced with inhibition. Using single-unit recordings from awake marmosets (Callithrix jacchus), we validate several model predictions, including differences in the temporal fidelity, discharge rates and temporal dynamics of stimulus-evoked responses between neurons with rate and temporal representations. Together these data suggest that feedforward inhibition provides a parsimonious explanation of the neural coding dichotomy observed in auditory cortex.
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Affiliation(s)
- Daniel Bendor
- Institute of Behavioural Neuroscience, Department of Experimental Psychology, University College London, London, United Kingdom
- * E-mail:
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25
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Zhao Y, Zhang Z, Liu X, Xiong C, Xiao Z, Yan J. Imbalance of excitation and inhibition at threshold level in the auditory cortex. Front Neural Circuits 2015; 9:11. [PMID: 25852485 PMCID: PMC4364151 DOI: 10.3389/fncir.2015.00011] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2014] [Accepted: 02/28/2015] [Indexed: 11/29/2022] Open
Abstract
The interplay of cortical excitation and inhibition is a fundamental feature of cortical information processing. Excitation and inhibition in single cortical neurons are balanced in their response to optimal sensory stimulation due to thalamocortical feedforward microcircuitry. It is unclear whether the balance between cortical excitation and inhibition is maintained at the threshold stimulus level. Using in vivo whole-cell patch-clamp recording of thalamocortical recipient neurons in the primary auditory cortex of mice, we examined the tone-evoked excitatory and inhibitory postsynaptic currents at threshold levels. Similar to previous reports, tone induced excitatory postsynaptic currents when the membrane potentials were held at 70 mV and inhibitory postsynaptic currents when the membrane potentials were held at 0 mV on single cortical neurons. This coupled excitation and inhibition is not demonstrated when threshold-level tone stimuli are presented. In most cases, tone induced only excitatory postsynaptic current. The best frequencies of excitatory and inhibitory responses were often different and thresholds of inhibitory responses were mostly higher than those of excitatory responses. Our data suggest that the excitatory and inhibitory inputs to single cortical neurons are imbalanced at the threshold level. This imbalance may result from the inherent dynamics of thalamocortical feedforward microcircuitry.
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Affiliation(s)
- Yan Zhao
- Department of Physiology, School of Basic Medical Science, Southern Medical University Guangzhou, China ; Department of Physiology and Pharmacology, Cumming School of Medicine, Hotchkiss Brain Institute, University of Calgary Calgary, AB, Canada
| | - Zizhen Zhang
- Department of Physiology and Pharmacology, Cumming School of Medicine, Hotchkiss Brain Institute, University of Calgary Calgary, AB, Canada
| | - Xiuping Liu
- Department of Physiology and Pharmacology, Cumming School of Medicine, Hotchkiss Brain Institute, University of Calgary Calgary, AB, Canada
| | - Colin Xiong
- Department of Physiology and Pharmacology, Cumming School of Medicine, Hotchkiss Brain Institute, University of Calgary Calgary, AB, Canada
| | - Zhongju Xiao
- Department of Physiology, School of Basic Medical Science, Southern Medical University Guangzhou, China
| | - Jun Yan
- Department of Physiology and Pharmacology, Cumming School of Medicine, Hotchkiss Brain Institute, University of Calgary Calgary, AB, Canada
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26
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Target-specific properties of thalamocortical synapses onto layer 4 of mouse primary visual cortex. J Neurosci 2015; 34:15455-65. [PMID: 25392512 DOI: 10.1523/jneurosci.2595-14.2014] [Citation(s) in RCA: 74] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
In primary sensory cortices, thalamocortical (TC) inputs can directly activate excitatory and inhibitory neurons. In vivo experiments in the main input layer (L4) of primary visual cortex (V1) have shown that excitatory and inhibitory neurons have different tuning properties. The different functional properties may arise from distinct intrinsic properties of L4 neurons, but could also depend on cell type-specific properties of the synaptic inputs from the lateral geniculate nucleus of the thalamus (LGN) onto L4 neurons. While anatomical studies identified LGN inputs onto both excitatory and inhibitory neurons in V1, their synaptic properties have not been investigated. Here we used an optogenetic approach to selectively activate LGN terminal fields in acute coronal slices containing V1, and recorded monosynaptic currents from excitatory and inhibitory neurons in L4. LGN afferents made monosynaptic connections with pyramidal (Pyr) and fast-spiking (FS) neurons. TC EPSCs on FS neurons were larger and showed steeper short-term depression in response to repetitive stimulation than those on Pyr neurons. LGN inputs onto Pyr and FS neurons also differed in postsynaptic receptor composition and organization of presynaptic release sites. Together, our results demonstrate that LGN input onto L4 neurons in mouse V1 have target-specific presynaptic and postsynaptic properties. Distinct mechanisms of activation of feedforward excitatory and inhibitory neurons in the main input layer of V1 are likely to endow neurons with different response properties to incoming visual stimuli.
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27
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Krause BM, Raz A, Uhlrich DJ, Smith PH, Banks MI. Spiking in auditory cortex following thalamic stimulation is dominated by cortical network activity. Front Syst Neurosci 2014; 8:170. [PMID: 25285071 PMCID: PMC4168681 DOI: 10.3389/fnsys.2014.00170] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2014] [Accepted: 08/31/2014] [Indexed: 12/23/2022] Open
Abstract
The state of the sensory cortical network can have a profound impact on neural responses and perception. In rodent auditory cortex, sensory responses are reported to occur in the context of network events, similar to brief UP states, that produce "packets" of spikes and are associated with synchronized synaptic input (Bathellier et al., 2012; Hromadka et al., 2013; Luczak et al., 2013). However, traditional models based on data from visual and somatosensory cortex predict that ascending sensory thalamocortical (TC) pathways sequentially activate cells in layers 4 (L4), L2/3, and L5. The relationship between these two spatio-temporal activity patterns is unclear. Here, we used calcium imaging and electrophysiological recordings in murine auditory TC brain slices to investigate the laminar response pattern to stimulation of TC afferents. We show that although monosynaptically driven spiking in response to TC afferents occurs, the vast majority of spikes fired following TC stimulation occurs during brief UP states and outside the context of the L4>L2/3>L5 activation sequence. Specifically, monosynaptic subthreshold TC responses with similar latencies were observed throughout layers 2-6, presumably via synapses onto dendritic processes located in L3 and L4. However, monosynaptic spiking was rare, and occurred primarily in L4 and L5 non-pyramidal cells. By contrast, during brief, TC-induced UP states, spiking was dense and occurred primarily in pyramidal cells. These network events always involved infragranular layers, whereas involvement of supragranular layers was variable. During UP states, spike latencies were comparable between infragranular and supragranular cells. These data are consistent with a model in which activation of auditory cortex, especially supragranular layers, depends on internally generated network events that represent a non-linear amplification process, are initiated by infragranular cells and tightly regulated by feed-forward inhibitory cells.
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Affiliation(s)
- Bryan M Krause
- Neuroscience Training Program, University of Wisconsin Madison, WI, USA
| | - Aeyal Raz
- Department of Anesthesiology, School of Medicine and Public Health, University of Wisconsin Madison, WI, USA ; Department of Anesthesiology, Rabin Medical Center, Petah-Tikva, Israel, affiliated with Sackler School of Medicine, Tel Aviv University Tel Aviv, Israel
| | - Daniel J Uhlrich
- Department of Neuroscience, School of Medicine and Public Health, University of Wisconsin Madison, WI, USA
| | - Philip H Smith
- Department of Neuroscience, School of Medicine and Public Health, University of Wisconsin Madison, WI, USA
| | - Matthew I Banks
- Department of Anesthesiology, School of Medicine and Public Health, University of Wisconsin Madison, WI, USA ; Department of Neuroscience, School of Medicine and Public Health, University of Wisconsin Madison, WI, USA
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28
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Mechanisms of noise robust representation of speech in primary auditory cortex. Proc Natl Acad Sci U S A 2014; 111:6792-7. [PMID: 24753585 DOI: 10.1073/pnas.1318017111] [Citation(s) in RCA: 74] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Humans and animals can reliably perceive behaviorally relevant sounds in noisy and reverberant environments, yet the neural mechanisms behind this phenomenon are largely unknown. To understand how neural circuits represent degraded auditory stimuli with additive and reverberant distortions, we compared single-neuron responses in ferret primary auditory cortex to speech and vocalizations in four conditions: clean, additive white and pink (1/f) noise, and reverberation. Despite substantial distortion, responses of neurons to the vocalization signal remained stable, maintaining the same statistical distribution in all conditions. Stimulus spectrograms reconstructed from population responses to the distorted stimuli resembled more the original clean than the distorted signals. To explore mechanisms contributing to this robustness, we simulated neural responses using several spectrotemporal receptive field models that incorporated either a static nonlinearity or subtractive synaptic depression and multiplicative gain normalization. The static model failed to suppress the distortions. A dynamic model incorporating feed-forward synaptic depression could account for the reduction of additive noise, but only the combined model with feedback gain normalization was able to predict the effects across both additive and reverberant conditions. Thus, both mechanisms can contribute to the abilities of humans and animals to extract relevant sounds in diverse noisy environments.
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29
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De Pasquale R, Sherman SM. A modulatory effect of the feedback from higher visual areas to V1 in the mouse. J Neurophysiol 2013; 109:2618-31. [PMID: 23446698 PMCID: PMC3653048 DOI: 10.1152/jn.01083.2012] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2012] [Accepted: 02/26/2013] [Indexed: 11/22/2022] Open
Abstract
Using a mouse brain slice preparation, we studied the modulatory effects of a feedback projection from higher visual cortical areas, mostly or exclusively area LM (or V2), on two inputs to layer 4 cells in the first visual area (V1). The two inputs to these cells were geniculocortical and an unspecified intracortical input, possibly involving layer 6 cells. We found that activation of metabotropic glutamate receptors (mGluRs) from stimulation of the feedback projection reduced the evoked excitatory postsynaptic currents of both of these inputs to layer 4 but that this modulation acts in an input-specific way. Reducing the strength of the geniculocortical input in adults involved both presynaptic and postsynaptic group I mGluRs (although in younger animals presynaptic group II mGluRs were also involved), whereas modulation of the intracortical input acted entirely via postsynaptic group II mGluRs. These results demonstrate that one of the effects of this feedback pathway is to control the gain of geniculocortical transmission.
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Affiliation(s)
- Roberto De Pasquale
- Department of Neurobiology, University of Chicago, Chicago, Illinois 60637, USA
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30
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Abstract
Flavoprotein autofluorescence imaging was used to examine auditory cortical synaptic responses in aged animals with behavioral evidence of tinnitus and hearing loss. Mice were exposed to noise trauma at 1-3 months of age and were assessed for behavioral evidence of tinnitus and hearing loss immediately after the noise trauma and again at ~24-30 months of age. Within 2 months of the final behavioral assessment, auditory cortical synaptic transmission was examined in brain slices using electrical stimulation of putative thalamocortical afferents, and flavoprotein autofluorescence imaging was used to measure cortical activation. Noise-exposed animals showed a 68% increase in amplitude of cortical activation compared with controls (p = 0.008), and these animals showed a diminished sensitivity to GABA(A)ergic blockade (p = 0.008, using bath-applied 200 nm SR 95531 [6-Imino-3-(4-methoxyphenyl)-1(6H)-p yridazinebutanoic acid hydrobromide]). The strength of cortical activation was significantly correlated to the degree of tinnitus behavior, assessed via a loss of gap detection in a startle paradigm. The decrease in GABA(A) sensitivity was greater in the regions of the cortex farther away from the stimulation site, potentially reflecting a greater sensitivity of corticocortical versus thalamocortical projections to the effects of noise trauma. Finally, there was no relationship between auditory cortical activation and activation of the somatosensory cortex in the same slices, suggesting that the increases in auditory cortical activation were not attributable to a generalized hyperexcitable state in noise-exposed animals. These data suggest that noise trauma can cause long-lasting changes in the auditory cortical physiology and may provide specific targets to ameliorate the effects of chronic tinnitus.
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31
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Broadening of inhibitory tuning underlies contrast-dependent sharpening of orientation selectivity in mouse visual cortex. J Neurosci 2013; 32:16466-77. [PMID: 23152629 DOI: 10.1523/jneurosci.3221-12.2012] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Orientation selectivity (OS) in the visual cortex has been found to be invariant to increases in stimulus contrast, a finding that cannot be accounted for by the original, purely excitatory Hubel and Wiesel model. This property of OS may be important for preserving the quality of perceived stimulus across a range of stimulus intensity. The synaptic mechanisms that can prevent a broadening of OS caused by contrast-dependent strengthening of excitatory inputs to cortical neurons remain unknown. Using in vivo loose-patch recordings, we found in excitatory neurons in layer 4 of mouse primary visual cortex (V1) that the spike response to the preferred orientation was elevated as contrast increased while that to the orthogonal orientation remained unchanged, resulting in an overall sharpening rather than a weakening of OS. Whole-cell voltage-clamp recordings further revealed that contrast increases resulted in a scaling up of excitatory conductance at all stimulus orientations. Inhibitory conductance was enhanced at a similar level as excitation for the preferred orientation, but at a significantly higher level for the orthogonal orientation. Modeling revealed that the resulting broadening of inhibitory tuning is critical for maintaining and sharpening OS at high contrast. Finally, two-photon imaging guided recordings from parvalbumin-positive (PV) inhibitory neurons revealed that the broadening of inhibition can be attributed to a contrast-dependent broadening of spike-response tuning of PV neurons. Together our results suggest that modulation of synaptic inhibition in the mouse V1 cortical circuit preserves the sharpness of response selectivity during changes of stimulus strength.
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Sakata S, Harris KD. Laminar-dependent effects of cortical state on auditory cortical spontaneous activity. Front Neural Circuits 2012; 6:109. [PMID: 23267317 PMCID: PMC3527822 DOI: 10.3389/fncir.2012.00109] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2012] [Accepted: 12/04/2012] [Indexed: 11/24/2022] Open
Abstract
Cortical circuits spontaneously generate coordinated activity even in the absence of external inputs. The character of this activity depends on cortical state. We investigated how state affects the organization of spontaneous activity across layers of rat auditory cortex in vivo, using juxtacellular recording of morphologically identified neurons and large-scale electrophysiological recordings. Superficial pyramidal cells (PCs) and putative fast-spiking interneurons (FSs) were consistently suppressed during cortical desynchronization. PCs in deep layers showed heterogeneous responses to desynchronization, with some cells showing increased rates, typically large tufted PCs of high baseline firing rate, but not FSs. Consistent results were found between desynchronization occurring spontaneously in unanesthetized animals, and desynchronization evoked by electrical stimulation of the pedunculopontine tegmental (PPT) nucleus under urethane anesthesia. We hypothesize that reduction in superficial layer firing may enhance the brain's extraction of behaviorally relevant signals from noisy brain activity.
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Affiliation(s)
- Shuzo Sakata
- Center for Molecular and Behavioral Neuroscience, Rutgers, The State University of New Jersey Newark, NJ, USA ; Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde Glasgow, UK ; Centre for Neuroscience, University of Strathclyde Glasgow, UK
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33
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Abstract
In many sensory systems, the latency of spike responses of individual neurons is found to be tuned for stimulus features and proposed to be used as a coding strategy. Whether the spike latency tuning is simply relayed along sensory ascending pathways or generated by local circuits remains unclear. Here, in vivo whole-cell recordings from rat auditory cortical neurons in layer 4 revealed that the onset latency of their aggregate thalamic input exhibited nearly flat tuning for sound frequency, whereas their spike latency tuning was much sharper with a broadly expanded dynamic range. This suggests that the spike latency tuning is not simply inherited from the thalamus, but can be largely reconstructed by local circuits in the cortex. Dissecting of thalamocortical circuits and neural modeling further revealed that broadly tuned intracortical inhibition prolongs the integration time for spike generation preferentially at off-optimal frequencies, while sharply tuned intracortical excitation shortens it selectively at the optimal frequency. Such push and pull mechanisms mediated likely by feedforward excitatory and inhibitory inputs respectively greatly sharpen the spike latency tuning and expand its dynamic range. The modulation of integration time by thalamocortical-like circuits may represent an efficient strategy for converting information spatially coded in synaptic strength to temporal representation.
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