151
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Abstract
Nervous systems use excitatory cell assemblies to encode and represent sensory percepts. Similarly, synaptically connected cell assemblies or "engrams" are thought to represent memories of past experience. Multiple lines of recent evidence indicate that brain systems create and use inhibitory replicas of excitatory representations for important cognitive functions. Such matched "inhibitory engrams" can form through homeostatic potentiation of inhibition onto postsynaptic cells that show increased levels of excitation. Inhibitory engrams can reduce behavioral responses to familiar stimuli, thereby resulting in behavioral habituation. In addition, by preventing inappropriate activation of excitatory memory engrams, inhibitory engrams can make memories quiescent, stored in a latent form that is available for context-relevant activation. In neural networks with balanced excitatory and inhibitory engrams, the release of innate responses and recall of associative memories can occur through focused disinhibition. Understanding mechanisms that regulate the formation and expression of inhibitory engrams in vivo may help not only to explain key features of cognition but also to provide insight into transdiagnostic traits associated with psychiatric conditions such as autism, schizophrenia, and posttraumatic stress disorder.
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152
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Cortical Predictive Mechanisms of Auditory Response Attenuation to Self-Generated Sounds. J Neurosci 2017; 37:5393-5394. [PMID: 28566419 DOI: 10.1523/jneurosci.0216-17.2017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2017] [Revised: 04/24/2017] [Accepted: 04/26/2017] [Indexed: 11/21/2022] Open
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153
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Tao C, Zhang G, Zhou C, Wang L, Yan S, Tao HW, Zhang LI, Zhou Y, Xiong Y. Diversity in Excitation-Inhibition Mismatch Underlies Local Functional Heterogeneity in the Rat Auditory Cortex. Cell Rep 2017; 19:521-531. [PMID: 28423316 DOI: 10.1016/j.celrep.2017.03.061] [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: 10/20/2016] [Revised: 02/09/2017] [Accepted: 03/21/2017] [Indexed: 11/29/2022] Open
Abstract
Cortical neurons are heterogeneous in their functional properties. This heterogeneity is fundamental for the processing of different features of sensory information. However, functional diversity within a local group of neurons is poorly understood. Here, we demonstrate that neighboring cortical neurons in layer 5 but not those of layer 4 of the rat anterior auditory field (AAF) exhibited a surprisingly high level of diversity in tonal receptive fields. In vivo whole-cell voltage-clamp recordings revealed that the diversity of frequency representation was due to a spectral mismatch between synaptic excitation and inhibition to varying degrees. The spectral distribution of excitation was skewed at different levels, whereas inhibition was homogeneous and non-skewed, similar to the summed spiking activity of local neuronal ensembles, which further enhanced diversity. Our results indicate that AAF in the auditory cortex is involved in processing auditory information in a highly refined manner that is important for complex pattern recognition.
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Affiliation(s)
- Can Tao
- Department of Neurobiology, Chongqing Key Laboratory of Neurobiology, Third Military Medical University, Chongqing 400038, China
| | - Guangwei Zhang
- Department of Neurobiology, Chongqing Key Laboratory of Neurobiology, Third Military Medical University, Chongqing 400038, China
| | - Chang Zhou
- Department of Neurobiology, Chongqing Key Laboratory of Neurobiology, Third Military Medical University, Chongqing 400038, China
| | - Lijuan Wang
- Department of Neurobiology, Chongqing Key Laboratory of Neurobiology, Third Military Medical University, Chongqing 400038, China
| | - Sumei Yan
- Department of Neurobiology, Chongqing Key Laboratory of Neurobiology, Third Military Medical University, Chongqing 400038, China
| | - Huizhong Whit Tao
- Zilkha Neurogenetic Institute, Keck School of Medicine, University of Southern California, Los Angeles, CA 90033, USA
| | - Li I Zhang
- Zilkha Neurogenetic Institute, Keck School of Medicine, University of Southern California, Los Angeles, CA 90033, USA
| | - Yi Zhou
- Department of Neurobiology, Chongqing Key Laboratory of Neurobiology, Third Military Medical University, Chongqing 400038, China.
| | - Ying Xiong
- Department of Neurobiology, Chongqing Key Laboratory of Neurobiology, Third Military Medical University, Chongqing 400038, China.
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154
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Rao VR, Leonard MK, Kleen JK, Lucas BA, Mirro EA, Chang EF. Chronic ambulatory electrocorticography from human speech cortex. Neuroimage 2017; 153:273-282. [PMID: 28396294 DOI: 10.1016/j.neuroimage.2017.04.008] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2017] [Revised: 03/15/2017] [Accepted: 04/04/2017] [Indexed: 01/07/2023] Open
Abstract
Direct intracranial recording of human brain activity is an important approach for deciphering neural mechanisms of cognition. Such recordings, usually made in patients with epilepsy undergoing inpatient monitoring for seizure localization, are limited in duration and depend on patients' tolerance for the challenges associated with recovering from brain surgery. Thus, typical intracranial recordings, similar to most non-invasive approaches in humans, provide snapshots of brain activity in acute, highly constrained settings, limiting opportunities to understand long timescale and natural, real-world phenomena. A new device for treating some forms of drug-resistant epilepsy, the NeuroPace RNS® System, includes a cranially-implanted neurostimulator and intracranial electrodes that continuously monitor brain activity and respond to incipient seizures with electrical counterstimulation. The RNS System can record epileptic brain activity over years, but whether it can record meaningful, behavior-related physiological responses has not been demonstrated. Here, in a human subject with electrodes implanted over high-level speech-auditory cortex (Wernicke's area; posterior superior temporal gyrus), we report that cortical evoked responses to spoken sentences are robust, selective to phonetic features, and stable over nearly 1.5 years. In a second subject with RNS System electrodes implanted over frontal cortex (Broca's area, posterior inferior frontal gyrus), we found that word production during a naming task reliably evokes cortical responses preceding speech onset. The spatiotemporal resolution, high signal-to-noise, and wireless nature of this system's intracranial recordings make it a powerful new approach to investigate the neural correlates of human cognition over long timescales in natural ambulatory settings.
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Affiliation(s)
- Vikram R Rao
- University of California, San Francisco, Department of Neurology, San Francisco, CA 94143, United States.
| | - Matthew K Leonard
- University of California, San Francisco, Department of Neurosurgery, San Francisco, CA 94143, United States; Weill Institute for Neurosciences, University of California, San Francisco, San Francisco, CA 94143, United States
| | - Jonathan K Kleen
- University of California, San Francisco, Department of Neurology, San Francisco, CA 94143, United States
| | - Ben A Lucas
- University of California, San Francisco, Department of Neurosurgery, San Francisco, CA 94143, United States; Weill Institute for Neurosciences, University of California, San Francisco, San Francisco, CA 94143, United States
| | - Emily A Mirro
- NeuroPace, Inc., Mountain View, CA 94043, United States
| | - Edward F Chang
- University of California, San Francisco, Department of Neurosurgery, San Francisco, CA 94143, United States; Weill Institute for Neurosciences, University of California, San Francisco, San Francisco, CA 94143, United States
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155
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Engaging in a tone-detection task differentially modulates neural activity in the auditory cortex, amygdala, and striatum. Sci Rep 2017; 7:677. [PMID: 28386101 PMCID: PMC5429729 DOI: 10.1038/s41598-017-00819-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2016] [Accepted: 03/14/2017] [Indexed: 11/19/2022] Open
Abstract
The relationship between attention and sensory coding is an area of active investigation. Previous studies have revealed that an animal’s behavioral state can play a crucial role in shaping the characteristics of neural responses in the auditory cortex (AC). However, behavioral modulation of auditory response in brain areas outside the AC is not well studied. In this study, we used the same experimental paradigm to examine the effects of attention on neural activity in multiple brain regions including the primary auditory cortex (A1), posterior auditory field (PAF), amygdala (AMY), and striatum (STR). Single-unit spike activity was recorded while cats were actively performing a tone-detection task or passively listening to the same tones. We found that tone-evoked neural responses in A1 were not significantly affected by task-engagement; however, those in PAF and AMY were enhanced, and those in STR were suppressed. The enhanced effect was associated with an improvement of accuracy of tone detection, which was estimated from the spike activity. Additionally, the firing rates of A1 and PAF neurons decreased upon motor response (licking) during the detection task. Our results suggest that attention may have different effects on auditory responsive brain areas depending on their physiological functions.
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156
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Zhang X, Sullivan CS, Kratz MB, Kasten MR, Maness PF, Manis PB. NCAM Regulates Inhibition and Excitability in Layer 2/3 Pyramidal Cells of Anterior Cingulate Cortex. Front Neural Circuits 2017; 11:19. [PMID: 28386219 PMCID: PMC5362729 DOI: 10.3389/fncir.2017.00019] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2016] [Accepted: 03/06/2017] [Indexed: 11/29/2022] Open
Abstract
The neural cell adhesion molecule (NCAM), has been shown to be an obligate regulator of synaptic stability and pruning during critical periods of cortical maturation. However, the functional consequences of NCAM deletion on the organization of inhibitory circuits in cortex are not known. In vesicular gamma-amino butyric acid (GABA) transporter (VGAT)-channelrhodopsin2 (ChR2)-enhanced yellow fluorescent protein (EYFP) transgenic mice, NCAM is expressed postnatally at perisomatic synaptic puncta of EYFP-labeled parvalbumin, somatostatin and calretinin-positive interneurons, and in the neuropil in the anterior cingulate cortex (ACC). To investigate how NCAM deletion affects the spatial organization of inhibitory inputs to pyramidal cells, we used laser scanning photostimulation in brain slices of VGAT-ChR2-EYFP transgenic mice crossed to either NCAM-null or wild type (WT) mice. Laser scanning photostimulation revealed that NCAM deletion increased the strength of close-in inhibitory connections to layer 2/3 pyramidal cells of the ACC. In addition, in NCAM-null mice, the intrinsic excitability of pyramidal cells increased, whereas the intrinsic excitability of GABAergic interneurons did not change. The increase in inhibitory tone onto pyramidal cells, and the increased pyramidal cell excitability in NCAM-null mice will alter the delicate coordination of excitation and inhibition (E/I coordination) in the ACC, and may be a factor contributing to circuit dysfunction in diseases such as schizophrenia and bipolar disorder, in which NCAM has been implicated.
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Affiliation(s)
- Xuying Zhang
- Department of Biochemistry and Biophysics, The University of North Carolina at Chapel Hill Chapel Hill, NC, USA
| | - Chelsea S Sullivan
- Department of Biochemistry and Biophysics, The University of North Carolina at Chapel Hill Chapel Hill, NC, USA
| | - Megan B Kratz
- Department of Otolaryngology/Head and Neck Surgery, The University of North Carolina at Chapel Hill Chapel Hill, NC, USA
| | - Michael R Kasten
- Department of Otolaryngology/Head and Neck Surgery, The University of North Carolina at Chapel Hill Chapel Hill, NC, USA
| | - Patricia F Maness
- Department of Biochemistry and Biophysics, The University of North Carolina at Chapel Hill Chapel Hill, NC, USA
| | - Paul B Manis
- Department of Otolaryngology/Head and Neck Surgery, The University of North Carolina at Chapel HillChapel Hill, NC, USA; Department of Cell Biology and Physiology, The University of North Carolina at Chapel HillChapel Hill, NC, USA
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157
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Guo L, Ponvert ND, Jaramillo S. The role of sensory cortex in behavioral flexibility. Neuroscience 2017; 345:3-11. [DOI: 10.1016/j.neuroscience.2016.03.067] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2015] [Revised: 03/01/2016] [Accepted: 03/29/2016] [Indexed: 12/14/2022]
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158
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Tsukano H, Horie M, Ohga S, Takahashi K, Kubota Y, Hishida R, Takebayashi H, Shibuki K. Reconsidering Tonotopic Maps in the Auditory Cortex and Lemniscal Auditory Thalamus in Mice. Front Neural Circuits 2017; 11:14. [PMID: 28293178 PMCID: PMC5330090 DOI: 10.3389/fncir.2017.00014] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2016] [Accepted: 02/20/2017] [Indexed: 11/13/2022] Open
Abstract
The auditory thalamus and auditory cortex (AC) are pivotal structures in the central auditory system. However, the thalamocortical mechanisms of processing sounds are largely unknown. Investigation of this process benefits greatly from the use of mice because the mouse is a powerful animal model in which various experimental techniques, especially genetic tools, can be applied. However, the use of mice has been limited in auditory research, and thus even basic anatomical knowledge of the mouse central auditory system has not been sufficiently collected. Recently, optical imaging combined with morphological analyses has enabled the elucidation of detailed anatomical properties of the mouse auditory system. These techniques have uncovered fine AC maps with multiple frequency-organized regions, each of which receives point-to-point thalamocortical projections from different origins inside the lemniscal auditory thalamus, the ventral division of the medial geniculate body (MGv). This precise anatomy now provides a platform for physiological research. In this mini review article, we summarize these recent achievements that will facilitate physiological investigations in the mouse auditory system.
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Affiliation(s)
- Hiroaki Tsukano
- Department of Neurophysiology, Brain Research Institute, Niigata University Niigata, Japan
| | - Masao Horie
- Division of Neurobiology and Anatomy, Graduate School of Medicine and Dental Sciences, Niigata University Niigata, Japan
| | - Shinpei Ohga
- Department of Neurophysiology, Brain Research Institute, Niigata University Niigata, Japan
| | - Kuniyuki Takahashi
- Division of Otolaryngology, Graduate School of Medicine and Dental Sciences, Niigata University Niigata, Japan
| | - Yamato Kubota
- Division of Otolaryngology, Graduate School of Medicine and Dental Sciences, Niigata University Niigata, Japan
| | - Ryuichi Hishida
- Department of Neurophysiology, Brain Research Institute, Niigata University Niigata, Japan
| | - Hirohide Takebayashi
- Division of Neurobiology and Anatomy, Graduate School of Medicine and Dental Sciences, Niigata University Niigata, Japan
| | - Katsuei Shibuki
- Department of Neurophysiology, Brain Research Institute, Niigata University Niigata, Japan
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159
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Yamada Y, Bhaukaurally K, Madarász TJ, Pouget A, Rodriguez I, Carleton A. Context- and Output Layer-Dependent Long-Term Ensemble Plasticity in a Sensory Circuit. Neuron 2017; 93:1198-1212.e5. [PMID: 28238548 PMCID: PMC5352733 DOI: 10.1016/j.neuron.2017.02.006] [Citation(s) in RCA: 49] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2016] [Revised: 11/10/2016] [Accepted: 02/03/2017] [Indexed: 01/14/2023]
Abstract
Sensory information is translated into ensemble representations by various populations of projection neurons in brain circuits. The dynamics of ensemble representations formed by distinct channels of output neurons in diverse behavioral contexts remains largely unknown. We studied the two output neuron layers in the olfactory bulb (OB), mitral and tufted cells, using chronic two-photon calcium imaging in awake mice. Both output populations displayed similar odor response profiles. During passive sensory experience, both populations showed reorganization of ensemble odor representations yet stable pattern separation across days. Intriguingly, during active odor discrimination learning, mitral but not tufted cells exhibited improved pattern separation, although both populations showed reorganization of ensemble representations. An olfactory circuitry model suggests that cortical feedback on OB interneurons can trigger both forms of plasticity. In conclusion, we show that different OB output layers display unique context-dependent long-term ensemble plasticity, allowing parallel transfer of non-redundant sensory information to downstream centers. Video Abstract
Mitral and tufted cells in the olfactory bulb show similar odor-evoked responses Passive odor experience reorganizes ensemble odor representations in both cell types Associative odor learning specifically improves pattern separation in mitral cells Cortical feedback can trigger both forms of plasticity in a network model
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Affiliation(s)
- Yoshiyuki Yamada
- Department of Basic Neurosciences, School of Medicine, University of Geneva, 1 Rue Michel-Servet, 1211 Geneva 4, Switzerland; Geneva Neuroscience Center, University of Geneva, 1211 Geneva, Switzerland
| | - Khaleel Bhaukaurally
- Department of Basic Neurosciences, School of Medicine, University of Geneva, 1 Rue Michel-Servet, 1211 Geneva 4, Switzerland; Geneva Neuroscience Center, University of Geneva, 1211 Geneva, Switzerland
| | - Tamás J Madarász
- Department of Basic Neurosciences, School of Medicine, University of Geneva, 1 Rue Michel-Servet, 1211 Geneva 4, Switzerland; Geneva Neuroscience Center, University of Geneva, 1211 Geneva, Switzerland
| | - Alexandre Pouget
- Department of Basic Neurosciences, School of Medicine, University of Geneva, 1 Rue Michel-Servet, 1211 Geneva 4, Switzerland; Geneva Neuroscience Center, University of Geneva, 1211 Geneva, Switzerland; Gatsby Computational Neuroscience Unit, University College London, London, W1T 4JG, UK
| | - Ivan Rodriguez
- Geneva Neuroscience Center, University of Geneva, 1211 Geneva, Switzerland; Department of Genetics and Evolution, University of Geneva, 1211 Geneva, Switzerland.
| | - Alan Carleton
- Department of Basic Neurosciences, School of Medicine, University of Geneva, 1 Rue Michel-Servet, 1211 Geneva 4, Switzerland; Geneva Neuroscience Center, University of Geneva, 1211 Geneva, Switzerland.
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160
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Does Size Really Matter? The Role of Tonotopic Map Area Dynamics for Sound Learning in Mouse Auditory Cortex. eNeuro 2017; 4:eN-COM-0002-17. [PMID: 28197554 PMCID: PMC5307296 DOI: 10.1523/eneuro.0002-17.2017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2017] [Revised: 01/03/2017] [Accepted: 01/04/2017] [Indexed: 11/21/2022] Open
Abstract
This commentary centers on the novel findings by Shepard et al. (2016) published in eNeuro. The authors interrogated tonotopic map dynamics in auditory cortex (ACtx) by employing a natural sound-learning paradigm, where mothers learn the importance of pup ultrasonic vocalizations (USVs), allowing Shepard et al. to probe the role of map area expansion for auditory learning. They demonstrate that auditory learning in this paradigm does not rely on map expansion but is facilitated by increased inhibition of neurons tuned to low-frequency sounds. Here, we discuss the findings in light of the emerging enthusiasm for cortical inhibitory interneurons for circuit function and hypothesize how a particular interneuron type might be causally involved for the intriguing results obtained by Shepard et al.
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161
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Keller AJ, Houlton R, Kampa BM, Lesica NA, Mrsic-Flogel TD, Keller GB, Helmchen F. Stimulus relevance modulates contrast adaptation in visual cortex. eLife 2017; 6. [PMID: 28130922 PMCID: PMC5298877 DOI: 10.7554/elife.21589] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2016] [Accepted: 01/27/2017] [Indexed: 12/16/2022] Open
Abstract
A general principle of sensory processing is that neurons adapt to sustained stimuli by reducing their response over time. Most of our knowledge on adaptation in single cells is based on experiments in anesthetized animals. How responses adapt in awake animals, when stimuli may be behaviorally relevant or not, remains unclear. Here we show that contrast adaptation in mouse primary visual cortex depends on the behavioral relevance of the stimulus. Cells that adapted to contrast under anesthesia maintained or even increased their activity in awake naïve mice. When engaged in a visually guided task, contrast adaptation re-occurred for stimuli that were irrelevant for solving the task. However, contrast adaptation was reversed when stimuli acquired behavioral relevance. Regulation of cortical adaptation by task demand may allow dynamic control of sensory-evoked signal flow in the neocortex. DOI:http://dx.doi.org/10.7554/eLife.21589.001
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Affiliation(s)
- Andreas J Keller
- Institute of Neuroinformatics, University of Zurich and ETH Zurich, Zürich, Switzerland.,Brain Research Institute, University of Zurich, Zürich, Switzerland.,Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland
| | - Rachael Houlton
- Department of Neuroscience, Physiology and Pharmacology, University College London, London, United Kingdom
| | - Björn M Kampa
- Brain Research Institute, University of Zurich, Zürich, Switzerland.,Department of Neurophysiology, Institute of Biology II, RWTH Aachen University, Aachen, Germany.,JARA BRAIN Institute for Neuroscience and Medicine, Forschungszentrum Jülich, Jülich, Germany
| | | | - Thomas D Mrsic-Flogel
- Department of Neuroscience, Physiology and Pharmacology, University College London, London, United Kingdom.,Biozentrum, University of Basel, Basel, Switzerland
| | - Georg B Keller
- Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland.,Faculty of Natural Sciences, University of Basel, Basel, Switzerland
| | - Fritjof Helmchen
- Brain Research Institute, University of Zurich, Zürich, Switzerland
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162
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Tsukano H, Horie M, Takahashi K, Hishida R, Takebayashi H, Shibuki K. Independent tonotopy and thalamocortical projection patterns in two adjacent parts of the classical primary auditory cortex in mice. Neurosci Lett 2017; 637:26-30. [DOI: 10.1016/j.neulet.2016.11.062] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2016] [Revised: 11/29/2016] [Accepted: 11/29/2016] [Indexed: 11/28/2022]
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163
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Kurkela JLO, Lipponen A, Hämäläinen JA, Näätänen R, Astikainen P. Passive exposure to speech sounds induces long-term memory representations in the auditory cortex of adult rats. Sci Rep 2016; 6:38904. [PMID: 27996015 PMCID: PMC5171838 DOI: 10.1038/srep38904] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2016] [Accepted: 11/15/2016] [Indexed: 11/09/2022] Open
Abstract
Experience-induced changes in the functioning of the auditory cortex are prominent in early life, especially during a critical period. Although auditory perceptual learning takes place automatically during this critical period, it is thought to require active training in later life. Previous studies demonstrated rapid changes in single-cell responses of anesthetized adult animals while exposed to sounds presented in a statistical learning paradigm. However, whether passive exposure to sounds can form long-term memory representations remains to be demonstrated. To investigate this issue, we first exposed adult rats to human speech sounds for 3 consecutive days, 12 h/d. Two groups of rats exposed to either spectrotemporal or tonal changes in speech sounds served as controls for each other. Then, electrophysiological brain responses from the auditory cortex were recorded to the same stimuli. In both the exposure and test phase statistical learning paradigm, was applied. The exposure effect was found for the spectrotemporal sounds, but not for the tonal sounds. Only the animals exposed to spectrotemporal sounds differentiated subtle changes in these stimuli as indexed by the mismatch negativity response. The results point to the occurrence of long-term memory traces for the speech sounds due to passive exposure in adult animals.
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Affiliation(s)
- Jari L O Kurkela
- Department of Psychology, University of Jyväskylä, Jyväskylä, Finland
| | - Arto Lipponen
- Department of Psychology, University of Jyväskylä, Jyväskylä, Finland
| | | | - Risto Näätänen
- Institute of Psychology, University of Tartu, Tartu, Estonia.,Center of Functionally Integrative Neurosciences (CFIN), University of Århus, Århus, Denmark.,Cognitive Brain Research Unit, Institute of Behavioural Sciences, University of Helsinki, Helsinki, Finland
| | - Piia Astikainen
- Department of Psychology, University of Jyväskylä, Jyväskylä, Finland
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164
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Contrast Enhancement without Transient Map Expansion for Species-Specific Vocalizations in Core Auditory Cortex during Learning. eNeuro 2016; 3:eN-NWR-0318-16. [PMID: 27957529 PMCID: PMC5128782 DOI: 10.1523/eneuro.0318-16.2016] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2016] [Revised: 11/05/2016] [Accepted: 11/07/2016] [Indexed: 11/25/2022] Open
Abstract
Tonotopic map plasticity in the adult auditory cortex (AC) is a well established and oft-cited measure of auditory associative learning in classical conditioning paradigms. However, its necessity as an enduring memory trace has been debated, especially given a recent finding that the areal expansion of core AC tuned to a newly relevant frequency range may arise only transiently to support auditory learning. This has been reinforced by an ethological paradigm showing that map expansion is not observed for ultrasonic vocalizations (USVs) or for ultrasound frequencies in postweaning dams for whom USVs emitted by pups acquire behavioral relevance. However, whether transient expansion occurs during maternal experience is not known, and could help to reveal the generality of cortical map expansion as a correlate for auditory learning. We thus mapped the auditory cortices of maternal mice at postnatal time points surrounding the peak in pup USV emission, but found no evidence of frequency map expansion for the behaviorally relevant high ultrasound range in AC. Instead, regions tuned to low frequencies outside of the ultrasound range show progressively greater suppression of activity in response to the playback of ultrasounds or pup USVs for maternally experienced animals assessed at their pups’ postnatal day 9 (P9) to P10, or postweaning. This provides new evidence for a lateral-band suppression mechanism elicited by behaviorally meaningful USVs, likely enhancing their population-level signal-to-noise ratio. These results demonstrate that tonotopic map enlargement has limits as a construct for conceptualizing how experience leaves neural memory traces within sensory cortex in the context of ethological auditory learning.
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165
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Parallel processing by cortical inhibition enables context-dependent behavior. Nat Neurosci 2016; 20:62-71. [PMID: 27798631 PMCID: PMC5191967 DOI: 10.1038/nn.4436] [Citation(s) in RCA: 224] [Impact Index Per Article: 24.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2016] [Accepted: 10/01/2016] [Indexed: 12/13/2022]
Abstract
Physical features of sensory stimuli are fixed, but sensory perception is context-dependent. The precise mechanisms that govern contextual modulation remain unknown. Here, we trained mice to switch between two contexts: passively listening to pure tones vs. performing a recognition task for the same stimuli. Two-photon imaging showed that many excitatory neurons in auditory cortex were suppressed, while some cells became more active during behavior. Whole-cell recordings showed that excitatory inputs were only modestly affected by context, but inhibition was more sensitive, with PV, SOM+, and VIP+ interneurons balancing inhibition/disinhibition within the network. Cholinergic modulation was involved in context-switching, with cholinergic axons increasing activity during behavior and directly depolarizing inhibitory cells. Network modeling captured these findings, but only when modulation coincidently drove all three interneuron subtypes, ruling out either inhibition or disinhibition alone as sole mechanism for active engagement. Parallel processing of cholinergic modulation by cortical interneurons therefore enables context-dependent behavior.
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166
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Yavorska I, Wehr M. Somatostatin-Expressing Inhibitory Interneurons in Cortical Circuits. Front Neural Circuits 2016; 10:76. [PMID: 27746722 PMCID: PMC5040712 DOI: 10.3389/fncir.2016.00076] [Citation(s) in RCA: 111] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2016] [Accepted: 09/12/2016] [Indexed: 12/30/2022] Open
Abstract
Cortical inhibitory neurons exhibit remarkable diversity in their morphology, connectivity, and synaptic properties. Here, we review the function of somatostatin-expressing (SOM) inhibitory interneurons, focusing largely on sensory cortex. SOM neurons also comprise a number of subpopulations that can be distinguished by their morphology, input and output connectivity, laminar location, firing properties, and expression of molecular markers. Several of these classes of SOM neurons show unique dynamics and characteristics, such as facilitating synapses, specific axonal projections, intralaminar input, and top-down modulation, which suggest possible computational roles. SOM cells can be differentially modulated by behavioral state depending on their class, sensory system, and behavioral paradigm. The functional effects of such modulation have been studied with optogenetic manipulation of SOM cells, which produces effects on learning and memory, task performance, and the integration of cortical activity. Different classes of SOM cells participate in distinct disinhibitory circuits with different inhibitory partners and in different cortical layers. Through these disinhibitory circuits, SOM cells help encode the behavioral relevance of sensory stimuli by regulating the activity of cortical neurons based on subcortical and intracortical modulatory input. Associative learning leads to long-term changes in the strength of connectivity of SOM cells with other neurons, often influencing the strength of inhibitory input they receive. Thus despite their heterogeneity and variability across cortical areas, current evidence shows that SOM neurons perform unique neural computations, forming not only distinct molecular but also functional subclasses of cortical inhibitory interneurons.
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Affiliation(s)
| | - Michael Wehr
- Institute of Neuroscience and Department of Psychology, University of OregonEugene, OR, USA
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Liguz-Lecznar M, Urban-Ciecko J, Kossut M. Somatostatin and Somatostatin-Containing Neurons in Shaping Neuronal Activity and Plasticity. Front Neural Circuits 2016; 10:48. [PMID: 27445703 PMCID: PMC4927943 DOI: 10.3389/fncir.2016.00048] [Citation(s) in RCA: 87] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2016] [Accepted: 06/20/2016] [Indexed: 01/27/2023] Open
Abstract
Since its discovery over four decades ago, somatostatin (SOM) receives growing scientific and clinical interest. Being localized in the nervous system in a subset of interneurons somatostatin acts as a neurotransmitter or neuromodulator and its role in the fine-tuning of neuronal activity and involvement in synaptic plasticity and memory formation are widely recognized in the recent literature. Combining transgenic animals with electrophysiological, anatomical and molecular methods allowed to characterize several subpopulations of somatostatin-containing interneurons possessing specific anatomical and physiological features engaged in controlling the output of cortical excitatory neurons. Special characteristic and connectivity of somatostatin-containing neurons set them up as significant players in shaping activity and plasticity of the nervous system. However, somatostatin is not just a marker of particular interneuronal subpopulation. Somatostatin itself acts pre- and postsynaptically, modulating excitability and neuronal responses. In the present review, we combine the knowledge regarding somatostatin and somatostatin-containing interneurons, trying to incorporate it into the current view concerning the role of the somatostatinergic system in cortical plasticity.
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Affiliation(s)
- Monika Liguz-Lecznar
- Department of Molecular and Cellular Neurobiology, Nencki Institute of Experimental Biology Warsaw, Poland
| | - Joanna Urban-Ciecko
- Department of Molecular and Cellular Neurobiology, Nencki Institute of Experimental BiologyWarsaw, Poland; Department of Biological Sciences and Center for the Neural Basis of Cognition, Carnegie Mellon UniversityPittsburgh, PA, USA
| | - Malgorzata Kossut
- Department of Molecular and Cellular Neurobiology, Nencki Institute of Experimental BiologyWarsaw, Poland; Department of Psychology, University of Social Sciences and Humanities (SWPS)Warsaw, Poland
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