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  • 1
    Online Resource
    Online Resource
    Ketamine anaesthesia induces gain enhancement via recurrent excitation in granular input layers of the auditory cortex
    Wiley ; 2020
    In:  The Journal of Physiology Vol. 598, No. 13 ( 2020-07), p. 2741-2755
    Details
    In: The Journal of Physiology, Wiley, Vol. 598, No. 13 ( 2020-07), p. 2741-2755
    Abstract: 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.
    Type of Medium: Online Resource
    ISSN: 0022-3751 , 1469-7793
    URL: Issue
    URL: Article
    DOI: 10.1113/tjp.v598.13
    DOI: 10.1113/JP279705
    RVK:
    WA 15000
    Language: English
    Publisher: Wiley
    Publication Date: 2020
    detail.hit.zdb_id: 1475290-6
    SSG: 12
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  • 2
    Online Resource
    Online Resource
    Optogenetic stimulation of the VTA modulates a frequency-specific gain of thalamocortical inputs in infragranular layers of the auditory cortex
    Springer Science and Business Media LLC ; 2019
    In:  Scientific Reports Vol. 9, No. 1 ( 2019-12-31)
    Details
    In: Scientific Reports, Springer Science and Business Media LLC, Vol. 9, No. 1 ( 2019-12-31)
    Abstract: Reward associations during auditory learning induce cortical plasticity in the primary auditory cortex. A prominent source of such influence is the ventral tegmental area (VTA), which conveys a dopaminergic teaching signal to the primary auditory cortex. Yet, it is unknown, how the VTA influences cortical frequency processing and spectral integration. Therefore, we investigated the temporal effects of direct optogenetic stimulation of the VTA onto spectral integration in the auditory cortex on a synaptic circuit level by current-source-density analysis in anesthetized Mongolian gerbils. While auditory lemniscal input predominantly terminates in the granular input layers III/IV, we found that VTA-mediated modulation of spectral processing is relayed by a different circuit, namely enhanced thalamic inputs to the infragranular layers Vb/VIa. Activation of this circuit yields a frequency-specific gain amplification of local sensory input and enhances corticocortical information transfer, especially in supragranular layers I/II. This effects persisted over more than 30 minutes after VTA stimulation. Altogether, we demonstrate that the VTA exhibits a long-lasting influence on sensory cortical processing via infragranular layers transcending the signaling of a mere reward-prediction error. We thereby demonstrate a cellular and circuit substrate for the influence of reinforcement-evaluating brain systems on sensory processing in the auditory cortex.
    Type of Medium: Online Resource
    ISSN: 2045-2322
    URL: Article
    DOI: 10.1038/s41598-019-56926-6
    Language: English
    Publisher: Springer Science and Business Media LLC
    Publication Date: 2019
    detail.hit.zdb_id: 2615211-3
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  • 3
    Online Resource
    Online Resource
    Task rule and choice are reflected by layer-specific processing in rodent auditory cortical microcircuits
    Springer Science and Business Media LLC ; 2020
    In:  Communications Biology Vol. 3, No. 1 ( 2020-07-03)
    Details
    In: Communications Biology, Springer Science and Business Media LLC, Vol. 3, No. 1 ( 2020-07-03)
    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.
    Type of Medium: Online Resource
    ISSN: 2399-3642
    URL: Article
    DOI: 10.1038/s42003-020-1073-3
    Language: English
    Publisher: Springer Science and Business Media LLC
    Publication Date: 2020
    detail.hit.zdb_id: 2919698-X
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  • 4
    Online Resource
    Online Resource
    Dopaminergic neuromodulation of high gamma stimulus phase‐locking in gerbil primary auditory cortex mediated by D1/D5‐receptors
    Wiley ; 2020
    In:  European Journal of Neuroscience Vol. 51, No. 5 ( 2020-03), p. 1315-1327
    Details
    In: European Journal of Neuroscience, Wiley, Vol. 51, No. 5 ( 2020-03), p. 1315-1327
    Abstract: Cortical release of the neurotransmitter dopamine has been implied in adapting cortical processing with respect to various functions including coding of stimulus salience, expectancy, error prediction, behavioral relevance and learning. Dopamine agonists have been shown to modulate recurrent cortico‐thalamic feedback, and should therefore also affect synchronization and amplitude of thalamo‐cortical oscillations. In this study, we have used multitaper spectral and time–frequency analysis of stimulus‐evoked and spontaneous current source density patterns in primary auditory cortex of Mongolian gerbils to characterize dopaminergic neuromodulation of the oscillatory structure of current sources and sinks. We systemically applied D1/D5‐receptor agonist SKF ‐38393 followed by competitive D1/D5‐receptor antagonist SCH ‐23390. Our results reveal an increase in stimulus phase‐locking in the high gamma‐band (88–97 Hz) by SKF ‐38393, specifically in layers III / IV at the best frequency, which occurred at 20 ms after tone onset, and was reversed by SCH ‐23390. However, changes in induced oscillatory power after SKF ‐38393 treatment occurred stimulus‐independently in the background activity in different layers than phase‐locking effects and were not reversed by SCH ‐23390. These effects might either reflect longer‐lasting changes in neural background noise, non‐specific changes due to ketamine anesthesia, or an interaction of both. Without concomitant stimulus‐induced power increase, increased stimulus phase‐locking in layers III / IV indicates enhanced phase‐resetting of neural oscillations by the stimulus after D1/D5‐receptor activation. The frequency characteristics, together with the demonstrated stimulus specificity and layer specificity, suggest that changes in phase‐resetting originate from dopaminergic neuromodulation of thalamo‐cortical interactions. Enhanced phase‐resetting might be a key step in the recruitment of cortical activity modes interpreting sensory input.
    Type of Medium: Online Resource
    ISSN: 0953-816X , 1460-9568
    URL: Issue
    URL: Article
    DOI: 10.1111/ejn.v51.5
    DOI: 10.1111/ejn.13898
    Language: English
    Publisher: Wiley
    Publication Date: 2020
    detail.hit.zdb_id: 2005178-5
    SSG: 12
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