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Macedo-Lima M, Hamlette LS, Caras ML. Orbitofrontal cortex modulates auditory cortical sensitivity and sound perception in Mongolian gerbils. Curr Biol 2024:S0960-9822(24)00820-0. [PMID: 38996534 DOI: 10.1016/j.cub.2024.06.036] [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: 01/05/2024] [Revised: 04/25/2024] [Accepted: 06/12/2024] [Indexed: 07/14/2024]
Abstract
Sensory perception is dynamic, quickly adapting to sudden shifts in environmental or behavioral context. Although decades of work have established that these dynamics are mediated by rapid fluctuations in sensory cortical activity, we have a limited understanding of the brain regions and pathways that orchestrate these changes. Neurons in the orbitofrontal cortex (OFC) encode contextual information, and recent data suggest that some of these signals are transmitted to sensory cortices. Whether and how these signals shape sensory encoding and perceptual sensitivity remain uncertain. Here, we asked whether the OFC mediates context-dependent changes in auditory cortical sensitivity and sound perception by monitoring and manipulating OFC activity in freely moving Mongolian gerbils of both sexes under two behavioral contexts: passive sound exposure and engagement in an amplitude modulation (AM) detection task. We found that the majority of OFC neurons, including the specific subset that innervates the auditory cortex, were strongly modulated by task engagement. Pharmacological inactivation of the OFC prevented rapid context-dependent changes in auditory cortical firing and significantly impaired behavioral AM detection. Our findings suggest that contextual information from the OFC mediates rapid plasticity in the auditory cortex and facilitates the perception of behaviorally relevant sounds.
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Affiliation(s)
| | | | - Melissa L Caras
- Department of Biology, University of Maryland, College Park, MD 20742, USA.
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2
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Deane KE, Klymentiev R, Heck J, Mark MD, Ohl FW, Heine M, Happel MFK. Inhibiting presynaptic calcium channel motility in the auditory cortex suppresses synchronized input processing. Front Cell Neurosci 2024; 18:1369047. [PMID: 38660672 PMCID: PMC11041022 DOI: 10.3389/fncel.2024.1369047] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2024] [Accepted: 03/18/2024] [Indexed: 04/26/2024] Open
Abstract
Introduction The emergent coherent population activity from thousands of stochastic neurons in the brain is believed to constitute a key neuronal mechanism for salient processing of external stimuli and its link to internal states like attention and perception. In the sensory cortex, functional cell assemblies are formed by recurrent excitation and inhibitory influences. The stochastic dynamics of each cell involved is largely orchestrated by presynaptic CAV2.1 voltage-gated calcium channels (VGCCs). Cav2.1 VGCCs initiate the release of neurotransmitters from the presynaptic compartment and are therefore able to add variability into synaptic transmission which can be partly explained by their mobile organization around docked vesicles. Methods To investigate the relevance of Cav2.1 channel surface motility for the input processing in the primary auditory cortex (A1) in vivo, we make use of a new optogenetic system which allows for acute, reversable cross-linking Cav2.1 VGCCs via a photo-cross-linkable cryptochrome mutant, CRY2olig. In order to map neuronal activity across all cortical layers of the A1, we performed laminar current-source density (CSD) recordings with varying auditory stimulus sets in transgenic mice with a citrine tag on the N-terminus of the VGCCs. Results Clustering VGCCs suppresses overall sensory-evoked population activity, particularly when stimuli lead to a highly synchronized distribution of synaptic inputs. Discussion Our findings reveal the importance of membrane dynamics of presynaptic calcium channels for sensory encoding by dynamically adjusting network activity across a wide range of synaptic input strength.
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Affiliation(s)
- Katrina E. Deane
- Leibniz Institute for Neurobiology, Magdeburg, Germany
- University of California, Riverside, Riverside, CA, United States
| | - Ruslan Klymentiev
- Leibniz Institute for Neurobiology, Magdeburg, Germany
- Institute of Biology, Otto von Guericke University, Magdeburg, Germany
| | - Jennifer Heck
- Leibniz Institute for Neurobiology, Magdeburg, Germany
- European Molecular Biology Laboratory, Heidelberg, Germany
| | - Melanie D. Mark
- Faculty of Biology and Biotechnology, Ruhr-University Bochum, Bochum, Germany
| | - Frank W. Ohl
- Leibniz Institute for Neurobiology, Magdeburg, Germany
- Institute of Biology, Otto von Guericke University, Magdeburg, Germany
- Center for Behavioral Brain Sciences (CBBS), Magdeburg, Germany
| | - Martin Heine
- Leibniz Institute for Neurobiology, Magdeburg, Germany
- Institute of Developmental Biology and Neurobiology, Johannes Gutenberg University Mainz, Mainz, Germany
| | - Max F. K. Happel
- Leibniz Institute for Neurobiology, Magdeburg, Germany
- Center for Behavioral Brain Sciences (CBBS), Magdeburg, Germany
- MSB Medical School Berlin, Medical Faculty, Berlin, Germany
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3
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Non-sensory Influences on Auditory Learning and Plasticity. J Assoc Res Otolaryngol 2022; 23:151-166. [PMID: 35235100 PMCID: PMC8964851 DOI: 10.1007/s10162-022-00837-3] [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: 08/10/2021] [Accepted: 12/30/2021] [Indexed: 10/19/2022] Open
Abstract
Distinguishing between regular and irregular heartbeats, conversing with speakers of different accents, and tuning a guitar-all rely on some form of auditory learning. What drives these experience-dependent changes? A growing body of evidence suggests an important role for non-sensory influences, including reward, task engagement, and social or linguistic context. This review is a collection of contributions that highlight how these non-sensory factors shape auditory plasticity and learning at the molecular, physiological, and behavioral level. We begin by presenting evidence that reward signals from the dopaminergic midbrain act on cortico-subcortical networks to shape sound-evoked responses of auditory cortical neurons, facilitate auditory category learning, and modulate the long-term storage of new words and their meanings. We then discuss the role of task engagement in auditory perceptual learning and suggest that plasticity in top-down cortical networks mediates learning-related improvements in auditory cortical and perceptual sensitivity. Finally, we present data that illustrates how social experience impacts sound-evoked activity in the auditory midbrain and forebrain and how the linguistic environment rapidly shapes speech perception. These findings, which are derived from both human and animal models, suggest that non-sensory influences are important regulators of auditory learning and plasticity and are often implemented by shared neural substrates. Application of these principles could improve clinical training strategies and inform the development of treatments that enhance auditory learning in individuals with communication disorders.
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Amaro D, Ferreiro DN, Grothe B, Pecka M. Source identity shapes spatial preference in primary auditory cortex during active navigation. Curr Biol 2021; 31:3875-3883.e5. [PMID: 34192513 DOI: 10.1016/j.cub.2021.06.025] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2021] [Revised: 05/10/2021] [Accepted: 06/09/2021] [Indexed: 01/05/2023]
Abstract
Information about the position of sensory objects and identifying their concurrent behavioral relevance is vital to navigate the environment. In the auditory system, spatial information is computed in the brain based on the position of the sound source relative to the observer and thus assumed to be egocentric throughout the auditory pathway. This assumption is largely based on studies conducted in either anesthetized or head-fixed and passively listening animals, thus lacking self-motion and selective listening. Yet these factors are fundamental components of natural sensing1 that may crucially impact the nature of spatial coding and sensory object representation.2 How individual objects are neuronally represented during unrestricted self-motion and active sensing remains mostly unexplored. Here, we trained gerbils on a behavioral foraging paradigm that required localization and identification of sound sources during free navigation. Chronic tetrode recordings in primary auditory cortex during task performance revealed previously unreported sensory object representations. Strikingly, the egocentric angle preference of the majority of spatially sensitive neurons changed significantly depending on the task-specific identity (outcome association) of the sound source. Spatial tuning also exhibited large temporal complexity. Moreover, we encountered egocentrically untuned neurons whose response magnitude differed between source identities. Using a neural network decoder, we show that, together, these neuronal response ensembles provide spatiotemporally co-existent information about both the egocentric location and the identity of individual sensory objects during self-motion, revealing a novel cortical computation principle for naturalistic sensing.
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Affiliation(s)
- Diana Amaro
- Division of Neurobiology, Department Biology II, Ludwig-Maximilians-Universität München, Planegg-Martinsried, Germany; Graduate School of Systemic Neurosciences, Ludwig-Maximilians-Universität München, Planegg-Martinsried, Germany
| | - Dardo N Ferreiro
- Division of Neurobiology, Department Biology II, Ludwig-Maximilians-Universität München, Planegg-Martinsried, Germany; Department of General Psychology and Education, Ludwig-Maximilians-Universität München, Germany
| | - Benedikt Grothe
- Division of Neurobiology, Department Biology II, Ludwig-Maximilians-Universität München, Planegg-Martinsried, Germany; Graduate School of Systemic Neurosciences, Ludwig-Maximilians-Universität München, Planegg-Martinsried, Germany; Max Planck Institute of Neurobiology, Planegg-Martinsried, Germany
| | - Michael Pecka
- Division of Neurobiology, Department Biology II, Ludwig-Maximilians-Universität München, Planegg-Martinsried, Germany.
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Saldeitis K, Jeschke M, Budinger E, Ohl FW, Happel MFK. Laser-Induced Apoptosis of Corticothalamic Neurons in Layer VI of Auditory Cortex Impact on Cortical Frequency Processing. Front Neural Circuits 2021; 15:659280. [PMID: 34322001 PMCID: PMC8311662 DOI: 10.3389/fncir.2021.659280] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2021] [Accepted: 06/14/2021] [Indexed: 12/20/2022] Open
Abstract
Corticofugal projections outnumber subcortical input projections by far. However, the specific role for signal processing of corticofugal feedback is still less well understood in comparisonto the feedforward projection. Here, we lesioned corticothalamic (CT) neurons in layers V and/or VI of the auditory cortex of Mongolian gerbils by laser-induced photolysis to investigate their contribution to cortical activation patterns. We have used laminar current-source density (CSD) recordings of tone-evoked responses and could show that, particularly, lesion of CT neurons in layer VI affected cortical frequency processing. Specifically, we found a decreased gain of best-frequency input in thalamocortical (TC)-recipient input layers that correlated with the relative lesion of layer VI neurons, but not layer V neurons. Using cortical silencing with the GABA a -agonist muscimol and layer-specific intracortical microstimulation (ICMS), we found that direct activation of infragranular layers recruited a local recurrent cortico-thalamo-cortical loop of synaptic input. This recurrent feedback was also only interrupted when lesioning layer VI neurons, but not cells in layer V. Our study thereby shows distinct roles of these two types of CT neurons suggesting a particular impact of CT feedback from layer VI to affect the local feedforward frequency processing in auditory cortex.
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Affiliation(s)
- Katja Saldeitis
- Department of Systems Physiology of Learning, Leibniz Institute for Neurobiology, Magdeburg, Germany.,Auditory Neuroscience and Optogenetics Group, Cognitive Hearing in Primates Lab, German Primate Center, Göttingen, Germany.,Institute for Auditory Neuroscience, University Medical Center Goettingen, Göttingen, Germany
| | - Marcus Jeschke
- Department of Systems Physiology of Learning, Leibniz Institute for Neurobiology, Magdeburg, Germany.,Auditory Neuroscience and Optogenetics Group, Cognitive Hearing in Primates Lab, German Primate Center, Göttingen, Germany.,Institute for Auditory Neuroscience, University Medical Center Goettingen, Göttingen, Germany
| | - Eike Budinger
- Department of Systems Physiology of Learning, Leibniz Institute for Neurobiology, Magdeburg, Germany.,Center for Behavioral Brain Sciences, Magdeburg, Germany
| | - Frank W Ohl
- Department of Systems Physiology of Learning, Leibniz Institute for Neurobiology, Magdeburg, Germany.,Institute for Auditory Neuroscience, University Medical Center Goettingen, Göttingen, Germany.,Institute of Biology (IBIO), University Magdeburg, Magdeburg, Germany
| | - Max F K Happel
- Department of Systems Physiology of Learning, Leibniz Institute for Neurobiology, Magdeburg, Germany.,Center for Behavioral Brain Sciences, Magdeburg, Germany.,Medical School Berlin, Berlin, Germany
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6
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Lin X, Brunk MGK, Yuanxiang P, Curran AW, Zhang E, Stöber F, Goldschmidt J, Gundelfinger ED, Vollmer M, Happel MFK, Herrera-Molina R, Montag D. Neuroplastin expression is essential for hearing and hair cell PMCA expression. Brain Struct Funct 2021; 226:1533-1551. [PMID: 33844052 PMCID: PMC8096745 DOI: 10.1007/s00429-021-02269-w] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2020] [Accepted: 03/27/2021] [Indexed: 12/25/2022]
Abstract
Hearing deficits impact on the communication with the external world and severely compromise perception of the surrounding. Deafness can be caused by particular mutations in the neuroplastin (Nptn) gene, which encodes a transmembrane recognition molecule of the immunoglobulin (Ig) superfamily and plasma membrane Calcium ATPase (PMCA) accessory subunit. This study investigates whether the complete absence of neuroplastin or the loss of neuroplastin in the adult after normal development lead to hearing impairment in mice analyzed by behavioral, electrophysiological, and in vivo imaging measurements. Auditory brainstem recordings from adult neuroplastin-deficient mice (Nptn-/-) show that these mice are deaf. With age, hair cells and spiral ganglion cells degenerate in Nptn-/- mice. Adult Nptn-/- mice fail to behaviorally respond to white noise and show reduced baseline blood flow in the auditory cortex (AC) as revealed by single-photon emission computed tomography (SPECT). In adult Nptn-/- mice, tone-evoked cortical activity was not detectable within the primary auditory field (A1) of the AC, although we observed non-persistent tone-like evoked activities in electrophysiological recordings of some young Nptn-/- mice. Conditional ablation of neuroplastin in Nptnlox/loxEmx1Cre mice reveals that behavioral responses to simple tones or white noise do not require neuroplastin expression by central glutamatergic neurons. Loss of neuroplastin from hair cells in adult NptnΔlox/loxPrCreERT mice after normal development is correlated with increased hearing thresholds and only high prepulse intensities result in effective prepulse inhibition (PPI) of the startle response. Furthermore, we show that neuroplastin is required for the expression of PMCA 2 in outer hair cells. This suggests that altered Ca2+ homeostasis underlies the observed hearing impairments and leads to hair cell degeneration. Our results underline the importance of neuroplastin for the development and the maintenance of the auditory system.
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Affiliation(s)
- Xiao Lin
- Neurogenetics Laboratory, Leibniz Institute for Neurobiology, Brenneckestr. 6, 39118, Magdeburg, Germany
- Department Neurochemistry and Molecular Biology, Leibniz Institute for Neurobiology, Brenneckestr. 6, 39118, Magdeburg, Germany
| | - Michael G K Brunk
- Department System Physiology and Learning, AG CortXplorer, Leibniz Institute for Neurobiology, Brenneckestr. 6, 39118, Magdeburg, Germany
| | - Pingan Yuanxiang
- Research Group Neuroplasticity, Leibniz Institute for Neurobiology, Brenneckestr. 6, 39118, Magdeburg, Germany
| | - Andrew W Curran
- Department System Physiology and Learning, Leibniz Institute for Neurobiology, Brenneckestr. 6, 39118, Magdeburg, Germany
| | - Enqi Zhang
- Institute of Medical Psychology, Otto-Von-Guericke University Magdeburg, University Hospital, Leipziger Str. 44, 39120, Magdeburg, Germany
| | - Franziska Stöber
- Department System Physiology and Learning, Leibniz Institute for Neurobiology, Brenneckestr. 6, 39118, Magdeburg, Germany
| | - Jürgen Goldschmidt
- Department System Physiology and Learning, Leibniz Institute for Neurobiology, Brenneckestr. 6, 39118, Magdeburg, Germany
- Center for Behavioral Brain Sciences (CBBS), 39106, Magdeburg, Germany
| | - Eckart D Gundelfinger
- Department Neurochemistry and Molecular Biology, Leibniz Institute for Neurobiology, Brenneckestr. 6, 39118, Magdeburg, Germany
- Medical Faculty, Molecular Neuroscience, Otto-Von-Guericke University Magdeburg, University Hospital, Leipziger Str. 44, 39120, Magdeburg, Germany
- Center for Behavioral Brain Sciences (CBBS), 39106, Magdeburg, Germany
| | - Maike Vollmer
- Department System Physiology and Learning, Leibniz Institute for Neurobiology, Brenneckestr. 6, 39118, Magdeburg, Germany
- Department of Otolaryngology-Head and Neck Surgery, Otto-Von-Guericke University Magdeburg, University Hospital, Leipziger Str. 44, 39120, Magdeburg, Germany
| | - Max F K Happel
- Department System Physiology and Learning, AG CortXplorer, Leibniz Institute for Neurobiology, Brenneckestr. 6, 39118, Magdeburg, Germany
- Center for Behavioral Brain Sciences (CBBS), 39106, Magdeburg, Germany
| | - Rodrigo Herrera-Molina
- Department Neurochemistry and Molecular Biology, Leibniz Institute for Neurobiology, Brenneckestr. 6, 39118, Magdeburg, Germany
- Centro Integrativo de Biología Y Química Aplicada, Universidad Bernardo O'Higgins, 8307993, Santiago, Chile
- Center for Behavioral Brain Sciences (CBBS), 39106, Magdeburg, Germany
| | - Dirk Montag
- Neurogenetics Laboratory, Leibniz Institute for Neurobiology, Brenneckestr. 6, 39118, Magdeburg, Germany.
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7
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The extracellular matrix regulates cortical layer dynamics and cross-columnar frequency integration in the auditory cortex. Commun Biol 2021; 4:322. [PMID: 33692502 PMCID: PMC7946889 DOI: 10.1038/s42003-021-01837-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2020] [Accepted: 02/11/2021] [Indexed: 01/31/2023] Open
Abstract
In the adult vertebrate brain, enzymatic removal of the extracellular matrix (ECM) is increasingly recognized to promote learning, memory recall, and restorative plasticity. The impact of the ECM on translaminar dynamics during cortical circuit processing is still not understood. Here, we removed the ECM in the primary auditory cortex (ACx) of adult Mongolian gerbils using local injections of hyaluronidase (HYase). Using laminar current-source density (CSD) analysis, we found layer-specific changes of the spatiotemporal synaptic patterns with increased cross-columnar integration and simultaneous weakening of early local sensory input processing within infragranular layers Vb. These changes had an oscillatory fingerprint within beta-band (25-36 Hz) selectively within infragranular layers Vb. To understand the laminar interaction dynamics after ECM digestion, we used time-domain conditional Granger causality (GC) measures to identify the increased drive of supragranular layers towards deeper infragranular layers. These results showed that ECM degradation altered translaminar cortical network dynamics with a stronger supragranular lead of the columnar response profile.
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8
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Zempeltzi MM, Kisse M, Brunk MGK, Glemser C, Aksit S, Deane KE, Maurya S, Schneider L, Ohl FW, Deliano M, Happel MFK. Task rule and choice are reflected by layer-specific processing in rodent auditory cortical microcircuits. Commun Biol 2020; 3:345. [PMID: 32620808 PMCID: PMC7335110 DOI: 10.1038/s42003-020-1073-3] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2019] [Accepted: 06/11/2020] [Indexed: 01/16/2023] Open
Abstract
The primary auditory cortex (A1) is an essential, integrative node that encodes the behavioral relevance of acoustic stimuli, predictions, and auditory-guided decision-making. However, the realization of this integration with respect to the cortical microcircuitry is not well understood. Here, we characterize layer-specific, spatiotemporal synaptic population activity with chronic, laminar current source density analysis in Mongolian gerbils (Meriones unguiculatus) trained in an auditory decision-making Go/NoGo shuttle-box task. We demonstrate that not only sensory but also task- and choice-related information is represented in the mesoscopic neuronal population code of A1. Based on generalized linear-mixed effect models we found a layer-specific and multiplexed representation of the task rule, action selection, and the animal's behavioral options as accumulating evidence in preparation of correct choices. The findings expand our understanding of how individual layers contribute to the integrative circuit in the sensory cortex in order to code task-relevant information and guide sensory-based decision-making.
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Affiliation(s)
| | - Martin Kisse
- Leibniz Institute for Neurobiology, D-39118, Magdeburg, Germany
| | | | - Claudia Glemser
- Leibniz Institute for Neurobiology, D-39118, Magdeburg, Germany
| | - Sümeyra Aksit
- Leibniz Institute for Neurobiology, D-39118, Magdeburg, Germany
| | - Katrina E Deane
- Leibniz Institute for Neurobiology, D-39118, Magdeburg, Germany
| | - Shivam Maurya
- Leibniz Institute for Neurobiology, D-39118, Magdeburg, Germany
| | - Lina Schneider
- Leibniz Institute for Neurobiology, D-39118, Magdeburg, Germany
| | - Frank W Ohl
- Leibniz Institute for Neurobiology, D-39118, Magdeburg, Germany
- Institute of Biology, Otto von Guericke University, D-39120, Magdeburg, Germany
- Center for Behavioral Brain Sciences (CBBS), 39106, Magdeburg, Germany
| | | | - Max F K Happel
- Leibniz Institute for Neurobiology, D-39118, Magdeburg, Germany.
- Center for Behavioral Brain Sciences (CBBS), 39106, Magdeburg, Germany.
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9
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Deane KE, Brunk MGK, Curran AW, Zempeltzi MM, Ma J, Lin X, Abela F, Aksit S, Deliano M, Ohl FW, Happel MFK. Ketamine anaesthesia induces gain enhancement via recurrent excitation in granular input layers of the auditory cortex. J Physiol 2020; 598:2741-2755. [PMID: 32329905 DOI: 10.1113/jp279705] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2020] [Accepted: 04/16/2020] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS Ketamine is a common anaesthetic agent used in research and more recently as medication in treatment of depression. It has known effects on inhibition of interneurons and cortical stimulus-locked responses, but the underlying functional network mechanisms are still elusive. Analysing population activity across all layers within the auditory cortex, we found that doses of this anaesthetic induce a stronger activation and stimulus-locked response to pure-tone stimuli. This cortical response is driven by gain enhancement of thalamocortical input processing selectively within granular layers due to an increased recurrent excitation. Time-frequency analysis indicates a higher broadband magnitude response and prolonged phase coherence in granular layers, possibly pointing to disinhibition of this recurrent excitation. These results further the understanding of ketamine's functional mechanisms, which will improve the ability to interpret physiological studies moving from anaesthetized to awake paradigms and may lead to the development of better ketamine-based depression treatments with lower side effects. ABSTRACT Ketamine is commonly used as an anaesthetic agent and has more recently gained attention as an antidepressant. It has been linked to increased stimulus-locked excitability, inhibition of interneurons and modulation of intrinsic neuronal oscillations. However, the functional network mechanisms are still elusive. A better understanding of these anaesthetic network effects may improve upon previous interpretations of seminal studies conducted under anaesthesia and have widespread relevance for neuroscience with awake and anaesthetized subjects as well as in medicine. Here, we investigated the effects of anaesthetic doses of ketamine (15 mg kg-1 h-1 i.p.) on the network activity after pure-tone stimulation within the auditory cortex of male Mongolian gerbils (Meriones unguiculatus). We used laminar current source density (CSD) analysis and subsequent layer-specific continuous wavelet analysis to investigate spatiotemporal response dynamics on cortical columnar processing in awake and ketamine-anaesthetized animals. We found thalamocortical input processing within granular layers III/IV to be significantly increased under ketamine. This layer-dependent gain enhancement under ketamine was not due to changes in cross-trial phase coherence but was rather attributed to a broadband increase in magnitude reflecting an increase in recurrent excitation. A time-frequency analysis was indicative of a prolonged period of stimulus-induced excitation possibly due to a reduced coupling of excitation and inhibition in granular input circuits - in line with the common hypothesis of cortical disinhibition via suppression of GABAergic interneurons.
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Affiliation(s)
- Katrina E Deane
- Leibniz Institute for Neurobiology, Magdeburg, D-39118, Germany
| | | | - Andrew W Curran
- Leibniz Institute for Neurobiology, Magdeburg, D-39118, Germany.,Graduate School of Life Science, Julius Maximilians University, Würzburg, D-97074, Germany
| | | | - Jing Ma
- Leibniz Institute for Neurobiology, Magdeburg, D-39118, Germany
| | - Xiao Lin
- Leibniz Institute for Neurobiology, Magdeburg, D-39118, Germany
| | - Francesca Abela
- Leibniz Institute for Neurobiology, Magdeburg, D-39118, Germany.,University of Pisa, Pisa, I-56126, Italy
| | - Sümeyra Aksit
- Leibniz Institute for Neurobiology, Magdeburg, D-39118, Germany
| | | | - Frank W Ohl
- Leibniz Institute for Neurobiology, Magdeburg, D-39118, Germany.,Institute of Biology, Otto von Guericke University, Magdeburg, D-39120, Germany.,Center for Behavioral Brain Sciences (CBBS), Magdeburg, 39106, Germany
| | - Max F K Happel
- Leibniz Institute for Neurobiology, Magdeburg, D-39118, Germany.,Institute of Biology, Otto von Guericke University, Magdeburg, D-39120, Germany.,Center for Behavioral Brain Sciences (CBBS), Magdeburg, 39106, Germany
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