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Alonso-Calviño E, Fernández-López E, Zaforas M, Rosa JM, Aguilar J. Increased excitability and reduced GABAergic levels in somatosensory cortex under chronic spinal cord injury. Exp Neurol 2023; 369:114504. [PMID: 37591355 DOI: 10.1016/j.expneurol.2023.114504] [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: 04/29/2023] [Revised: 07/07/2023] [Accepted: 08/11/2023] [Indexed: 08/19/2023]
Abstract
The complete or partial damage of ascending somatosensory pathways produced by a spinal cord injury triggers changes in the somatosensory cortex consisting in a functional expansion of activity from intact cortical regions towards deafferented ones, a process known as cortical reorganization. However, it is still unclear whether cortical reorganization depends on the severity of the spinal cord damage or if a spinal cord injury always leads to a similar cortical reorganization process in the somatosensory cortex. To answer these open questions in the field, we obtained longitudinal somatosensory evoked responses from bilateral hindlimb and forelimb cortex from animals with chronic full-transection or contusive spinal cord injury at thoracic level (T9-T10) to induce sensory deprivation of hindlimb cortex while preserving intact the forelimb cortex. Electrophysiological recordings from the four locations were obtained before lesion and weekly for up to 4 weeks. Our results show that cortical reorganization depends on the type of spinal cord injury, which tends to be more bilateral in full transection while is more unilateral in the model of contusive spinal cord injury. Moreover, in full transection of spinal cord, the deafferented and intact cortex exhibited similar increments of somatosensory evoked responses in both models of spinal cord injury - a feature observed in about 80% of subjects. The other 20% were unaffected by the injury indicating that cortical reorganization does not undergo in all subjects. In addition, we demonstrated an increased probability of triggered up-states in animals with spinal cord injury. This data indicates increased cortical excitability that could be proposed as a new feature of cortical reorganization. Finally, decreased levels of GABA marker GAD67 across cortical layers were only found in those animals with increased somatosensory evoked responses, but not in the unaffected population. In conclusion, cortical reorganization depends on the types of spinal cord injuries, and suggest that the phenomenon is strongly determined by cortical circuits. Moreover, changes in GABAergic transmission at the deprived cortex may be considered one of the mechanisms underlying the process of cortical reorganization and increased excitability.
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Affiliation(s)
- Elena Alonso-Calviño
- Experimental Neurophysiology Group, Hospital Nacional de Parapléjicos, SESCAM, Toledo, Spain; Instituto de Investigación Sanitaria de Castilla-La Mancha (IDISCAM), Toledo, Spain
| | - Elena Fernández-López
- Experimental Neurophysiology Group, Hospital Nacional de Parapléjicos, SESCAM, Toledo, Spain; Instituto de Investigación Sanitaria de Castilla-La Mancha (IDISCAM), Toledo, Spain
| | - Marta Zaforas
- Experimental Neurophysiology Group, Hospital Nacional de Parapléjicos, SESCAM, Toledo, Spain; Instituto de Investigación Sanitaria de Castilla-La Mancha (IDISCAM), Toledo, Spain
| | - Juliana M Rosa
- Neuronal Circuits and Behaviour Group, Hospital Nacional de Parapléjicos, SESCAM, Toledo, Spain; Instituto de Investigación Sanitaria de Castilla-La Mancha (IDISCAM), Toledo, Spain
| | - Juan Aguilar
- Experimental Neurophysiology Group, Hospital Nacional de Parapléjicos, SESCAM, Toledo, Spain; Instituto de Investigación Sanitaria de Castilla-La Mancha (IDISCAM), Toledo, Spain.
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Ljungquist B, Akram MA, Ascoli GA. Large scale similarity search across digital reconstructions of neural morphology. Neurosci Res 2022; 181:39-45. [PMID: 35580795 PMCID: PMC9960175 DOI: 10.1016/j.neures.2022.05.004] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2022] [Revised: 04/12/2022] [Accepted: 05/12/2022] [Indexed: 01/18/2023]
Abstract
Most functions of the nervous system depend on neuronal and glial morphology. Continuous advances in microscopic imaging and tracing software have provided an increasingly abundant availability of 3D reconstructions of arborizing dendrites, axons, and processes, allowing their detailed study. However, efficient, large-scale methods to rank neural morphologies by similarity to an archetype are still lacking. Using the NeuroMorpho.Org database, we present a similarity search software enabling fast morphological comparison of hundreds of thousands of neural reconstructions from any species, brain regions, cell types, and preparation protocols. We compared the performance of different morphological measurements: 1) summary morphometrics calculated by L-Measure, 2) persistence vectors, a vectorized descriptor of branching structure, 3) the combination of the two. In all cases, we also investigated the impact of applying dimensionality reduction using principal component analysis (PCA). We assessed qualitative performance by gauging the ability to rank neurons in order of visual similarity. Moreover, we quantified information content by examining explained variance and benchmarked the ability to identify occasional duplicate reconstructions of the same specimen. We also compared two different methods for selecting the number of principal components using this benchmark. The results indicate that combining summary morphometrics and persistence vectors with applied PCA using maximum likelihood based automatic dimensionality selection provides an information rich characterization that enables efficient and precise comparison of neural morphology. We have deployed the similarity search as open-source online software both through a user-friendly graphical interface and as an API for programmatic access.
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Affiliation(s)
- Bengt Ljungquist
- Center for Neural Informatics, Structures, & Plasticity and Bioengineering Department, George Mason University, Mail Stop 2A1, 4400 University Dr, Fairfax, VA, United States of America
| | - Masood A Akram
- Center for Neural Informatics, Structures, & Plasticity and Bioengineering Department, George Mason University, Mail Stop 2A1, 4400 University Dr, Fairfax, VA, United States of America
| | - Giorgio A Ascoli
- Center for Neural Informatics, Structures, & Plasticity and Bioengineering Department, George Mason University, Mail Stop 2A1, 4400 University Dr, Fairfax, VA, United States of America.
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Zaforas M, Rosa JM, Alonso-Calviño E, Fernández-López E, Miguel-Quesada C, Oliviero A, Aguilar J. Cortical layer-specific modulation of neuronal activity after sensory deprivation due to spinal cord injury. J Physiol 2021; 599:4643-4669. [PMID: 34418097 PMCID: PMC9292026 DOI: 10.1113/jp281901] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2021] [Accepted: 08/19/2021] [Indexed: 11/28/2022] Open
Abstract
Abstract Cortical areas have the capacity of large‐scale reorganization following sensory deafferentation. However, it remains unclear whether this phenomenon is a unique process that homogeneously affects the entire deprived cortical region or whether it is susceptible to changes depending on neuronal networks across distinct cortical layers. Here, we studied how the local circuitry within each layer of the deafferented cortex forms the basis for neuroplastic changes after immediate thoracic spinal cord injury (SCI) in anaesthetized rats. In vivo electrophysiological recordings from deafferented hindlimb somatosensory cortex showed that SCI induces layer‐specific changes mediating evoked and spontaneous activity. In supragranular layer 2/3, SCI increased gamma oscillations and the ability of these neurons to initiate up‐states during spontaneous activity, suggesting an altered corticocortical network and/or intrinsic properties that may serve to maintain the excitability of the cortical column after deafferentation. On the other hand, SCI enhanced the infragranular layers’ ability to integrate evoked sensory inputs leading to increased and faster neuronal responses. Delayed evoked response onsets were also observed in layer 5/6, suggesting alterations in thalamocortical connectivity. Altogether, our data indicate that SCI immediately modifies the local circuitry within the deafferented cortex allowing supragranular layers to better integrate spontaneous corticocortical information, thus modifying column excitability, and infragranular layers to better integrate evoked sensory inputs to preserve subcortical outputs. These layer‐specific neuronal changes may guide the long‐term alterations in neuronal excitability and plasticity associated with the rearrangements of somatosensory networks and the appearance of central sensory pathologies usually associated with spinal cord injury. Key points Sensory stimulation of forelimb produces cortical evoked responses in the somatosensory hindlimb cortex in a layer‐dependent manner. Spinal cord injury favours the input statistics of corticocortical connections between intact and deafferented cortices. After spinal cord injury supragranular layers exhibit better integration of spontaneous corticocortical information while infragranular layers exhibit better integration of evoked sensory stimulation. Cortical reorganization is a layer‐specific phenomenon.
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Affiliation(s)
- Marta Zaforas
- Experimental Neurophysiology and Neuronal Circuits Group, Research Unit, Hospital Nacional de Parapléjicos - SESCAM, Toledo, 45071, Spain.,FENNSI Group, Hospital Nacional de Parapléjicos - SESCAM, Research Unit, Toledo, 45071, Spain
| | - Juliana M Rosa
- Experimental Neurophysiology and Neuronal Circuits Group, Research Unit, Hospital Nacional de Parapléjicos - SESCAM, Toledo, 45071, Spain
| | - Elena Alonso-Calviño
- Experimental Neurophysiology and Neuronal Circuits Group, Research Unit, Hospital Nacional de Parapléjicos - SESCAM, Toledo, 45071, Spain
| | - Elena Fernández-López
- Experimental Neurophysiology and Neuronal Circuits Group, Research Unit, Hospital Nacional de Parapléjicos - SESCAM, Toledo, 45071, Spain
| | - Claudia Miguel-Quesada
- Experimental Neurophysiology and Neuronal Circuits Group, Research Unit, Hospital Nacional de Parapléjicos - SESCAM, Toledo, 45071, Spain
| | - Antonio Oliviero
- FENNSI Group, Hospital Nacional de Parapléjicos - SESCAM, Research Unit, Toledo, 45071, Spain
| | - Juan Aguilar
- Experimental Neurophysiology and Neuronal Circuits Group, Research Unit, Hospital Nacional de Parapléjicos - SESCAM, Toledo, 45071, Spain
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Enhanced Thalamocortical Synaptic Transmission and Dysregulation of the Excitatory-Inhibitory Balance at the Thalamocortical Feedforward Inhibitory Microcircuit in a Genetic Mouse Model of Migraine. J Neurosci 2019; 39:9841-9851. [PMID: 31645463 DOI: 10.1523/jneurosci.1840-19.2019] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2019] [Revised: 09/05/2019] [Accepted: 09/22/2019] [Indexed: 12/22/2022] Open
Abstract
Migraine is a complex brain disorder, characterized by attacks of unilateral headache and global dysfunction in multisensory information processing, whose underlying cellular and circuit mechanisms remain unknown. The finding of enhanced excitatory, but unaltered inhibitory, neurotransmission at intracortical synapses in mouse models of familial hemiplegic migraine (FHM) suggested the hypothesis that dysregulation of the excitatory-inhibitory balance in specific circuits is a key pathogenic mechanism. Here, we investigated the thalamocortical (TC) feedforward inhibitory microcircuit in FHM1 mice of both sexes carrying a gain-of-function mutation in CaV2.1. We show that TC synaptic transmission in somatosensory cortex is enhanced in FHM1 mice. Due to similar gain of function of TC excitation of layer 4 excitatory and fast-spiking inhibitory neurons elicited by single thalamic stimulations, neither the excitatory-inhibitory balance nor the integration time window set by the TC feedforward inhibitory microcircuit was altered in FHM1 mice. However, during repetitive thalamic stimulation, the typical shift of the excitatory-inhibitory balance toward excitation and the widening of the integration time window were both smaller in FHM1 compared with WT mice, revealing a dysregulation of the excitatory-inhibitory balance, whereby the balance is relatively skewed toward inhibition. This is due to an unexpected differential effect of the FHM1 mutation on short-term synaptic plasticity at TC synapses on cortical excitatory and fast-spiking inhibitory neurons. Our findings point to enhanced transmission of sensory, including trigeminovascular nociceptive, signals from thalamic nuclei to cortex and TC excitatory-inhibitory imbalance as mechanisms that may contribute to headache, increased sensory gain, and sensory processing dysfunctions in migraine.SIGNIFICANCE STATEMENT Migraine is a complex brain disorder, characterized by attacks of unilateral headache and by global dysfunction in multisensory information processing, whose underlying cellular and circuit mechanisms remain unknown. Here we provide insights into these mechanisms by investigating thalamocortical (TC) synaptic transmission and the function of the TC feedforward inhibitory microcircuit in a mouse model of a rare monogenic migraine. This microcircuit is critical for gating information flow to cortex and for sensory processing. We reveal increased TC transmission and dysregulation of the cortical excitatory-inhibitory balance set by the TC feedforward inhibitory microcircuit, whereby the balance is relatively skewed toward inhibition during repetitive thalamic activity. These alterations may contribute to headache, increased sensory gain, and sensory processing dysfunctions in migraine.
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Fine-scale mapping of cortical laminar activity during sleep slow oscillations using high-density linear silicon probes. J Neurosci Methods 2018; 316:58-70. [PMID: 30144495 DOI: 10.1016/j.jneumeth.2018.08.020] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2018] [Revised: 08/16/2018] [Accepted: 08/17/2018] [Indexed: 12/14/2022]
Abstract
BACKGROUND The cortical slow (∼1 Hz) oscillation (SO), which is thought to play an active role in the consolidation of memories, is a brain rhythm characteristic of slow-wave sleep, with alternating periods of neuronal activity and silence. Although the laminar distribution of cortical activity during SO is well-studied by using linear neural probes, traditional devices have a relatively low (20-100 μm) spatial resolution along cortical layers. NEW METHOD In this work, we demonstrate a high-density linear silicon probe fabricated to record the SO with very high spatial resolution (∼6 μm), simultaneously from multiple cortical layers. Ketamine/xylazine-induced SO was acquired acutely from the neocortex of rats, followed by the examination of the high-resolution laminar structure of cortical activity. RESULTS The probe provided high-quality extracellular recordings, and the obtained cortical laminar profiles of the SO were in good agreement with the literature data. Furthermore, we could record the simultaneous activity of 30-50 cortical single units. Spiking activity of these neurons showed layer-specific differences. COMPARISON WITH EXISTING METHODS The developed silicon probe measures neuronal activity with at least a three-fold higher spatial resolution compared with traditional linear probes. By exploiting this feature, we could determine the site of up-state initiation with a higher precision than before. Additionally, increased spatial resolution may provide more reliable spike sorting results, as well as a higher single unit yield. CONCLUSIONS The high spatial resolution provided by the electrodes allows to examine the fine structure of local population activity during sleep SO in greater detail.
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Effects of Low Doses of Ketamine on Pyramidal Neurons in Rat Prefrontal Cortex. Neuroscience 2018; 384:178-187. [DOI: 10.1016/j.neuroscience.2018.05.037] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2018] [Revised: 05/22/2018] [Accepted: 05/23/2018] [Indexed: 12/30/2022]
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Sigalas C, Konsolaki E, Skaliora I. Sex differences in endogenous cortical network activity: spontaneously recurring Up/Down states. Biol Sex Differ 2017; 8:21. [PMID: 28630662 PMCID: PMC5471918 DOI: 10.1186/s13293-017-0143-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/25/2016] [Accepted: 06/06/2017] [Indexed: 03/02/2023] Open
Abstract
BACKGROUND Several molecular and cellular processes in the vertebrate brain exhibit differences between males and females, leading to sexual dimorphism in the formation of neural circuits and brain organization. While studies on large-scale brain networks provide ample evidence for both structural and functional sex differences, smaller-scale local networks have remained largely unexplored. In the current study, we investigate sexual dimorphism in cortical dynamics by means of spontaneous Up/Down states, a type of network activity that is exhibited during slow-wave sleep, quiet wakefulness, and anesthesia and is thought to represent the default activity of the cortex. METHODS Up state activity was monitored by local field potential recordings in coronal brain slices of male and female mice across three ages with distinct secretion profiles of sex hormones: (i) pre-puberty (17-21 days old), (ii) 3-9 adult (months old), and (iii) old (19-24 months old). RESULTS Female mice of all ages exhibited longer and more frequent Up states compared to aged-matched male mice. Power spectrum analysis revealed sex differences in the relative power of Up state events, with female mice showing reduced power in the delta range (1-4 Hz) and increased power in the theta range (4-8 Hz) compared to male mice. No sex differences were found in the characteristics of Up state peak voltage and latency. CONCLUSIONS The present study revealed for the first time sex differences in intracortical network activity, using an ex vivo paradigm of spontaneously occurring Up/Down states. We report significant sex differences in Up state properties that are already present in pre-puberty animals and are maintained through adulthood and old age.
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Affiliation(s)
- Charalambos Sigalas
- Neurophysiology Laboratory, Centre for Basic Research, Biomedical Research Foundation of the Academy of Athens, 4 Soranou Efessiou Street, Athens, 115 27 Greece
| | - Eleni Konsolaki
- Psychology Department, Deree - The American College of Greece, Athens, 153 42 Greece
| | - Irini Skaliora
- Neurophysiology Laboratory, Centre for Basic Research, Biomedical Research Foundation of the Academy of Athens, 4 Soranou Efessiou Street, Athens, 115 27 Greece
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Distinct mechanisms of Up state maintenance in the medial entorhinal cortex and neocortex. Neuropharmacology 2017; 113:543-555. [PMID: 27838344 PMCID: PMC5154331 DOI: 10.1016/j.neuropharm.2016.11.009] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2016] [Revised: 11/02/2016] [Accepted: 11/08/2016] [Indexed: 02/02/2023]
Abstract
The medial entorhinal cortex (mEC) is a key structure which controls the communication between the hippocampus and the neocortex. During slow-wave sleep, it stands out from other cortical regions by exhibiting persistent activity that outlasts neocortical Up states, decoupling the entorhinal cortex-hippocampal interaction from the neocortex. Here, we compared the mechanisms involved in the maintenance of the Up state in the barrel cortex (BC) and mEC using whole cell recordings in acute mouse brain slices. Bath application of an NMDA receptor antagonist abolished Up states in the BC, and reduced the incidence but not the duration of Up states in the mEC. Conversely, blockade of kainate receptors decreased Up state duration in the mEC, but not in the BC. Voltage clamp recordings demonstrated the presence of a non-NMDA glutamate receptor-mediated slow excitatory postsynaptic current, sensitive to the selective kainate receptor antagonist UBP-302, in layer III neurons of the mEC, which was not observed in the BC. Moreover, we found that kainate receptor-mediated currents assist in recovery back to the Up state membrane potential following a current-induced hyperpolarisation of individual cells in the mEC. Finally, we were able to generate Up state activity in a network model of exponential integrate-and-fire neurons only supported by AMPA and kainate receptor-mediated currents. We propose that synaptic kainate receptors are responsible for the unique properties of mEC Up states.
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Castro-Alamancos MA, Favero M. Whisker-related afferents in superior colliculus. J Neurophysiol 2016; 115:2265-79. [PMID: 26864754 DOI: 10.1152/jn.00028.2016] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2016] [Accepted: 02/03/2016] [Indexed: 11/22/2022] Open
Abstract
Rodents use their whiskers to explore the environment, and the superior colliculus is part of the neural circuits that process this sensorimotor information. Cells in the intermediate layers of the superior colliculus integrate trigeminotectal afferents from trigeminal complex and corticotectal afferents from barrel cortex. Using histological methods in mice, we found that trigeminotectal and corticotectal synapses overlap somewhat as they innervate the lower and upper portions of the intermediate granular layer, respectively. Using electrophysiological recordings and optogenetics in anesthetized mice in vivo, we showed that, similar to rats, whisker deflections produce two successive responses that are driven by trigeminotectal and corticotectal afferents. We then employed in vivo and slice experiments to characterize the response properties of these afferents. In vivo, corticotectal responses triggered by electrical stimulation of the barrel cortex evoke activity in the superior colliculus that increases with stimulus intensity and depresses with increasing frequency. In slices from adult mice, optogenetic activation of channelrhodopsin-expressing trigeminotectal and corticotectal fibers revealed that cells in the intermediate layers receive more efficacious trigeminotectal, than corticotectal, synaptic inputs. Moreover, the efficacy of trigeminotectal inputs depresses more strongly with increasing frequency than that of corticotectal inputs. The intermediate layers of superior colliculus appear to be tuned to process strong but infrequent trigeminal inputs and weak but more persistent cortical inputs, which explains features of sensory responsiveness, such as the robust rapid sensory adaptation of whisker responses in the superior colliculus.
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Affiliation(s)
- Manuel A Castro-Alamancos
- Department of Neurobiology and Anatomy, Drexel University College of Medicine, Philadelphia, Pennsylvania
| | - Morgana Favero
- Department of Neurobiology and Anatomy, Drexel University College of Medicine, Philadelphia, Pennsylvania
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Neske GT. The Slow Oscillation in Cortical and Thalamic Networks: Mechanisms and Functions. Front Neural Circuits 2016; 9:88. [PMID: 26834569 PMCID: PMC4712264 DOI: 10.3389/fncir.2015.00088] [Citation(s) in RCA: 136] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2015] [Accepted: 12/21/2015] [Indexed: 12/03/2022] Open
Abstract
During even the most quiescent behavioral periods, the cortex and thalamus express rich spontaneous activity in the form of slow (<1 Hz), synchronous network state transitions. Throughout this so-called slow oscillation, cortical and thalamic neurons fluctuate between periods of intense synaptic activity (Up states) and almost complete silence (Down states). The two decades since the original characterization of the slow oscillation in the cortex and thalamus have seen considerable advances in deciphering the cellular and network mechanisms associated with this pervasive phenomenon. There are, nevertheless, many questions regarding the slow oscillation that await more thorough illumination, particularly the mechanisms by which Up states initiate and terminate, the functional role of the rhythmic activity cycles in unconscious or minimally conscious states, and the precise relation between Up states and the activated states associated with waking behavior. Given the substantial advances in multineuronal recording and imaging methods in both in vivo and in vitro preparations, the time is ripe to take stock of our current understanding of the slow oscillation and pave the way for future investigations of its mechanisms and functions. My aim in this Review is to provide a comprehensive account of the mechanisms and functions of the slow oscillation, and to suggest avenues for further exploration.
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Affiliation(s)
- Garrett T Neske
- Department of Neuroscience, Division of Biology and Medicine, Brown UniversityProvidence, RI, USA; Department of Neurobiology, Yale UniversityNew Haven, CT, USA
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Rigas P, Adamos DA, Sigalas C, Tsakanikas P, Laskaris NA, Skaliora I. Spontaneous Up states in vitro: a single-metric index of the functional maturation and regional differentiation of the cerebral cortex. Front Neural Circuits 2015; 9:59. [PMID: 26528142 PMCID: PMC4603250 DOI: 10.3389/fncir.2015.00059] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2015] [Accepted: 09/22/2015] [Indexed: 12/12/2022] Open
Abstract
Understanding the development and differentiation of the neocortex remains a central focus of neuroscience. While previous studies have examined isolated aspects of cellular and synaptic organization, an integrated functional index of the cortical microcircuit is still lacking. Here we aimed to provide such an index, in the form of spontaneously recurring periods of persistent network activity -or Up states- recorded in mouse cortical slices. These coordinated network dynamics emerge through the orchestrated regulation of multiple cellular and synaptic elements and represent the default activity of the cortical microcircuit. To explore whether spontaneous Up states can capture developmental changes in intracortical networks we obtained local field potential recordings throughout the mouse lifespan. Two independent and complementary methodologies revealed that Up state activity is systematically modified by age, with the largest changes occurring during early development and adolescence. To explore possible regional heterogeneities we also compared the development of Up states in two distinct cortical areas and show that primary somatosensory cortex develops at a faster pace than primary motor cortex. Our findings suggest that in vitro Up states can serve as a functional index of cortical development and differentiation and can provide a baseline for comparing experimental and/or genetic mouse models.
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Affiliation(s)
- Pavlos Rigas
- Neurophysiology Laboratory, Center for Basic Research, Biomedical Research Foundation of the Academy of AthensAthens, Greece
| | - Dimitrios A. Adamos
- Neuroinformatics Group, Aristotle University of ThessalonikiThessaloniki, Greece
- School of Music Studies, Aristotle University of ThessalonikiThessaloniki, Greece
| | - Charalambos Sigalas
- Neurophysiology Laboratory, Center for Basic Research, Biomedical Research Foundation of the Academy of AthensAthens, Greece
| | - Panagiotis Tsakanikas
- Neurophysiology Laboratory, Center for Basic Research, Biomedical Research Foundation of the Academy of AthensAthens, Greece
| | - Nikolaos A. Laskaris
- Neuroinformatics Group, Aristotle University of ThessalonikiThessaloniki, Greece
- AIIA Lab, Department of Informatics, Aristotle University of ThessalonikiThessaloniki, Greece
| | - Irini Skaliora
- Neurophysiology Laboratory, Center for Basic Research, Biomedical Research Foundation of the Academy of AthensAthens, Greece
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Castro-Alamancos MA, Favero M. NMDA receptors are the basis for persistent network activity in neocortex slices. J Neurophysiol 2015; 113:3816-26. [PMID: 25878152 DOI: 10.1152/jn.00090.2015] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2015] [Accepted: 04/15/2015] [Indexed: 11/22/2022] Open
Abstract
During behavioral quiescence the neocortex generates spontaneous slow oscillations that consist of Up and Down states. Up states are short epochs of persistent activity, but their underlying source is unclear. In neocortex slices of adult mice, we monitored several cellular and network variables during the transition between a traditional buffer, which does not cause Up states, and a lower-divalent cation buffer, which leads to the generation of Up states. We found that the resting membrane potential and input resistance of cortical cells did not change with the development of Up states. The synaptic efficacy of excitatory postsynaptic potentials mediated by non-NMDA receptors was slightly reduced, but this is unlikely to facilitate the generation of Up states. On the other hand, we identified two variables that are associated with the generation of Up states: an enhancement of the intrinsic firing excitability of cortical cells and an enhancement of NMDA-mediated responses evoked by electrical or optogenetic stimulation. The fact that blocking NMDA receptors abolishes Up states indicates that the enhancement in intrinsic firing excitability alone is insufficient to generate Up states. NMDA receptors have a crucial role in the generation of Up states in neocortex slices.
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Affiliation(s)
- Manuel A Castro-Alamancos
- Department of Neurobiology and Anatomy, Drexel University College of Medicine, Philadelphia, Pennsylvania
| | - Morgana Favero
- Department of Neurobiology and Anatomy, Drexel University College of Medicine, Philadelphia, Pennsylvania
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13
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Sceniak MP, Lang M, Enomoto AC, James Howell C, Hermes DJ, Katz DM. Mechanisms of Functional Hypoconnectivity in the Medial Prefrontal Cortex of Mecp2 Null Mice. Cereb Cortex 2015; 26:1938-1956. [PMID: 25662825 DOI: 10.1093/cercor/bhv002] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Frontal cortical dysfunction is thought to contribute to cognitive and behavioral features of autism spectrum disorders; however, underlying mechanisms are poorly understood. The present study sought to define how loss of Mecp2, the gene mutated in Rett syndrome (RTT), disrupts function in the murine medial prefrontal cortex (mPFC) using acute brain slices and behavioral testing. Compared with wildtype, pyramidal neurons in the Mecp2 null mPFC exhibit significant reductions in excitatory postsynaptic currents, the duration of excitatory UP-states, evoked population activity, and the ratio of NMDA:AMPA currents, as well as an increase in the relative fraction of NR2B currents. These functional changes are associated with reductions in the density of excitatory dendritic spines, the ratio of vesicular glutamate to GABA transporters and GluN1 expression. In contrast to recent reports on circuit defects in other brain regions, we observed no effect of Mecp2 loss on inhibitory synaptic currents or expression of the inhibitory marker parvalbumin. Consistent with mPFC hypofunction, Mecp2 nulls exhibit respiratory dysregulation in response to behavioral arousal. Our data highlight functional hypoconnectivity in the mPFC as a potential substrate for behavioral disruption in RTT and other disorders associated with reduced expression of Mecp2 in frontal cortical regions.
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Affiliation(s)
- Michael P Sceniak
- Department of Neurosciences, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA
| | - Min Lang
- Department of Neurosciences, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA
| | - Addison C Enomoto
- Department of Neurosciences, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA
| | - C James Howell
- Department of Neurosciences, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA
| | - Douglas J Hermes
- Department of Neurosciences, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA
| | - David M Katz
- Department of Neurosciences, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA
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Barbosa DJ, Capela JP, de Lourdes Bastos M, Carvalho F. In vitro models for neurotoxicology research. Toxicol Res (Camb) 2015; 4:801-842. [DOI: 10.1039/c4tx00043a] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/01/2023] Open
Abstract
The nervous system has a highly complex organization, including many cell types with multiple functions, with an intricate anatomy and unique structural and functional characteristics; the study of its (dys)functionality following exposure to xenobiotics, neurotoxicology, constitutes an important issue in neurosciences.
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Affiliation(s)
- Daniel José Barbosa
- REQUIMTE (Rede de Química e Tecnologia)
- Laboratório de Toxicologia
- Departamento de Ciências Biológicas
- Faculdade de Farmácia
- Universidade do Porto
| | - João Paulo Capela
- REQUIMTE (Rede de Química e Tecnologia)
- Laboratório de Toxicologia
- Departamento de Ciências Biológicas
- Faculdade de Farmácia
- Universidade do Porto
| | - Maria de Lourdes Bastos
- REQUIMTE (Rede de Química e Tecnologia)
- Laboratório de Toxicologia
- Departamento de Ciências Biológicas
- Faculdade de Farmácia
- Universidade do Porto
| | - Félix Carvalho
- REQUIMTE (Rede de Química e Tecnologia)
- Laboratório de Toxicologia
- Departamento de Ciências Biológicas
- Faculdade de Farmácia
- Universidade do Porto
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15
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Garcia I, Quast KB, Huang L, Herman AM, Selever J, Deussing JM, Justice NJ, Arenkiel BR. Local CRH signaling promotes synaptogenesis and circuit integration of adult-born neurons. Dev Cell 2014; 30:645-59. [PMID: 25199688 DOI: 10.1016/j.devcel.2014.07.001] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2013] [Revised: 05/02/2014] [Accepted: 06/30/2014] [Indexed: 01/09/2023]
Abstract
Neural activity either enhances or impairs de novo synaptogenesis and circuit integration of neurons, but how this activity is mechanistically relayed in the adult brain is largely unknown. Neuropeptide-expressing interneurons are widespread throughout the brain and are key candidates for conveying neural activity downstream via neuromodulatory pathways that are distinct from classical neurotransmission. With the goal of identifying signaling mechanisms that underlie neuronal circuit integration in the adult brain, we have virally traced local corticotropin-releasing hormone (CRH)-expressing inhibitory interneurons with extensive presynaptic inputs onto new neurons that are continuously integrated into the adult rodent olfactory bulb. Local CRH signaling onto adult-born neurons promotes and/or stabilizes chemical synapses in the olfactory bulb, revealing a neuromodulatory mechanism for continued circuit plasticity, synapse formation, and integration of new neurons in the adult brain.
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Affiliation(s)
- Isabella Garcia
- Program in Developmental Biology, Baylor College of Medicine, Houston, TX 77030, USA; Medical Scientist Training Program, Baylor College of Medicine, Houston, TX 77030, USA
| | - Kathleen B Quast
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Longwen Huang
- Department of Neuroscience, Baylor College of Medicine, Houston, TX 77030, USA
| | - Alexander M Herman
- Program in Developmental Biology, Baylor College of Medicine, Houston, TX 77030, USA
| | - Jennifer Selever
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Jan M Deussing
- Max Planck Institute of Psychiatry, 80804 Munich, Germany
| | - Nicholas J Justice
- Institute of Molecular Medicine, University of Texas Health Science Center at Houston, Houston, TX 77030, USA
| | - Benjamin R Arenkiel
- Program in Developmental Biology, Baylor College of Medicine, Houston, TX 77030, USA; Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA; Department of Neuroscience, Baylor College of Medicine, Houston, TX 77030, USA; Jan and Dan Duncan Neurological Research Institute at Texas Children's Hospital, Houston, TX 77030, USA.
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16
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Gambino F, Pagès S, Kehayas V, Baptista D, Tatti R, Carleton A, Holtmaat A. Sensory-evoked LTP driven by dendritic plateau potentials in vivo. Nature 2014; 515:116-9. [DOI: 10.1038/nature13664] [Citation(s) in RCA: 180] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2014] [Accepted: 07/07/2014] [Indexed: 02/08/2023]
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17
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Abstract
Methods to control neural activity by light have been introduced to the field of neuroscience. During the last decade, several techniques have been established, including optogenetics, thermogenetics, and infrared neural stimulation. The techniques allow investigators to turn-on or turn-off neural activity. This review is an attempt to show the importance of the techniques for the auditory field and provide insight in the similarities, overlap, and differences of the techniques. Discussing the mechanism of each of the techniques will shed light on the abilities and challenges for each of the techniques. The field has been grown tremendously and a review cannot be complete. However, efforts are made to summarize the important points and to refer the reader to excellent papers and reviews to specific topics. This article is part of a Special Issue entitled .
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Affiliation(s)
- Claus-Peter Richter
- Northwestern University Feinberg School of Medicine, Department of Otolaryngology, 303 E. Chicago Ave, Searle 12-561, Chicago, IL 60611, USA; Dept. of Biomedical Engineering, Northwestern University, 2145 Sheridan Road, Tech E310, Evanston, IL 60208, USA; The Hugh Knowles Center, Department of Communication Sciences and Disorders, Northwestern University, Evanston, IL 60208, USA.
| | - Xiaodong Tan
- Northwestern University Feinberg School of Medicine, Department of Otolaryngology, 303 E. Chicago Ave, Searle 12-561, Chicago, IL 60611, USA
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