1
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McCollum M, Manning A, Bender PTR, Mendelson BZ, Anderson CT. Cell-type-specific enhancement of deviance detection by synaptic zinc in the mouse auditory cortex. Proc Natl Acad Sci U S A 2024; 121:e2405615121. [PMID: 39312661 PMCID: PMC11459170 DOI: 10.1073/pnas.2405615121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2024] [Accepted: 08/15/2024] [Indexed: 09/25/2024] Open
Abstract
Stimulus-specific adaptation is a hallmark of sensory processing in which a repeated stimulus results in diminished successive neuronal responses, but a deviant stimulus will still elicit robust responses from the same neurons. Recent work has established that synaptically released zinc is an endogenous mechanism that shapes neuronal responses to sounds in the auditory cortex. Here, to understand the contributions of synaptic zinc to deviance detection of specific neurons, we performed wide-field and 2-photon calcium imaging of multiple classes of cortical neurons. We find that intratelencephalic (IT) neurons in both layers 2/3 and 5 as well as corticocollicular neurons in layer 5 all demonstrate deviance detection; however, we find a specific enhancement of deviance detection in corticocollicular neurons that arises from ZnT3-dependent synaptic zinc in layer 2/3 IT neurons. Genetic deletion of ZnT3 from layer 2/3 IT neurons removes the enhancing effects of synaptic zinc on corticocollicular neuron deviance detection and results in poorer acuity of detecting deviant sounds by behaving mice.
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Affiliation(s)
- Mason McCollum
- Department of Neuroscience, Rockefeller Neuroscience Institute, West Virginia University School of Medicine, Morgantown, WV26505
| | - Abbey Manning
- Department of Neuroscience, Rockefeller Neuroscience Institute, West Virginia University School of Medicine, Morgantown, WV26505
| | - Philip T. R. Bender
- Department of Neuroscience, Rockefeller Neuroscience Institute, West Virginia University School of Medicine, Morgantown, WV26505
| | - Benjamin Z. Mendelson
- Department of Neuroscience, Rockefeller Neuroscience Institute, West Virginia University School of Medicine, Morgantown, WV26505
| | - Charles T. Anderson
- Department of Neuroscience, Rockefeller Neuroscience Institute, West Virginia University School of Medicine, Morgantown, WV26505
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2
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Quass GL, Rogalla MM, Ford AN, Apostolides PF. Mixed Representations of Sound and Action in the Auditory Midbrain. J Neurosci 2024; 44:e1831232024. [PMID: 38918064 PMCID: PMC11270520 DOI: 10.1523/jneurosci.1831-23.2024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2023] [Revised: 06/05/2024] [Accepted: 06/14/2024] [Indexed: 06/27/2024] Open
Abstract
Linking sensory input and its consequences is a fundamental brain operation. During behavior, the neural activity of neocortical and limbic systems often reflects dynamic combinations of sensory and task-dependent variables, and these "mixed representations" are suggested to be important for perception, learning, and plasticity. However, the extent to which such integrative computations might occur outside of the forebrain is less clear. Here, we conduct cellular-resolution two-photon Ca2+ imaging in the superficial "shell" layers of the inferior colliculus (IC), as head-fixed mice of either sex perform a reward-based psychometric auditory task. We find that the activity of individual shell IC neurons jointly reflects auditory cues, mice's actions, and behavioral trial outcomes, such that trajectories of neural population activity diverge depending on mice's behavioral choice. Consequently, simple classifier models trained on shell IC neuron activity can predict trial-by-trial outcomes, even when training data are restricted to neural activity occurring prior to mice's instrumental actions. Thus, in behaving mice, auditory midbrain neurons transmit a population code that reflects a joint representation of sound, actions, and task-dependent variables.
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Affiliation(s)
- Gunnar L Quass
- Department of Otolaryngology-Head & Neck Surgery, Kresge Hearing Research Institute, University of Michigan Medical School, Ann Arbor, Michigan 48109
| | - Meike M Rogalla
- Department of Otolaryngology-Head & Neck Surgery, Kresge Hearing Research Institute, University of Michigan Medical School, Ann Arbor, Michigan 48109
| | - Alexander N Ford
- Department of Otolaryngology-Head & Neck Surgery, Kresge Hearing Research Institute, University of Michigan Medical School, Ann Arbor, Michigan 48109
| | - Pierre F Apostolides
- Department of Otolaryngology-Head & Neck Surgery, Kresge Hearing Research Institute, University of Michigan Medical School, Ann Arbor, Michigan 48109
- Department of Molecular and Integrative Physiology, University of Michigan Medical School, Ann Arbor, Michigan 48109
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3
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Ying R, Stolzberg DJ, Caras ML. Neural correlates of flexible sound perception in the auditory midbrain and thalamus. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.04.12.589266. [PMID: 38645241 PMCID: PMC11030403 DOI: 10.1101/2024.04.12.589266] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/23/2024]
Abstract
Hearing is an active process in which listeners must detect and identify sounds, segregate and discriminate stimulus features, and extract their behavioral relevance. Adaptive changes in sound detection can emerge rapidly, during sudden shifts in acoustic or environmental context, or more slowly as a result of practice. Although we know that context- and learning-dependent changes in the spectral and temporal sensitivity of auditory cortical neurons support many aspects of flexible listening, the contribution of subcortical auditory regions to this process is less understood. Here, we recorded single- and multi-unit activity from the central nucleus of the inferior colliculus (ICC) and the ventral subdivision of the medial geniculate nucleus (MGV) of Mongolian gerbils under two different behavioral contexts: as animals performed an amplitude modulation (AM) detection task and as they were passively exposed to AM sounds. Using a signal detection framework to estimate neurometric sensitivity, we found that neural thresholds in both regions improved during task performance, and this improvement was driven by changes in firing rate rather than phase locking. We also found that ICC and MGV neurometric thresholds improved and correlated with behavioral performance as animals learn to detect small AM depths during a multi-day perceptual training paradigm. Finally, we reveal that in the MGV, but not the ICC, context-dependent enhancements in AM sensitivity grow stronger during perceptual training, mirroring prior observations in the auditory cortex. Together, our results suggest that the auditory midbrain and thalamus contribute to flexible sound processing and perception over rapid and slow timescales.
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Affiliation(s)
- Rose Ying
- Neuroscience and Cognitive Science Program, University of Maryland, College Park, Maryland, 20742
- Department of Biology, University of Maryland, College Park, Maryland, 20742
- Center for Comparative and Evolutionary Biology of Hearing, University of Maryland, College Park, Maryland, 20742
| | - Daniel J. Stolzberg
- Department of Biology, University of Maryland, College Park, Maryland, 20742
| | - Melissa L. Caras
- Neuroscience and Cognitive Science Program, University of Maryland, College Park, Maryland, 20742
- Department of Biology, University of Maryland, College Park, Maryland, 20742
- Center for Comparative and Evolutionary Biology of Hearing, University of Maryland, College Park, Maryland, 20742
- Department of Hearing and Speech Sciences, University of Maryland, College Park, Maryland, 20742
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4
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Asokan MM, Watanabe Y, Kimchi EY, Polley DB. Potentiation of cholinergic and corticofugal inputs to the lateral amygdala in threat learning. Cell Rep 2023; 42:113167. [PMID: 37742187 PMCID: PMC10879743 DOI: 10.1016/j.celrep.2023.113167] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2023] [Revised: 07/07/2023] [Accepted: 09/07/2023] [Indexed: 09/26/2023] Open
Abstract
The amygdala, cholinergic basal forebrain, and higher-order auditory cortex (HO-AC) regulate brain-wide plasticity underlying auditory threat learning. Here, we perform multi-regional extracellular recordings and optical measurements of acetylcholine (ACh) release to characterize the development of discriminative plasticity within and between these brain regions as mice acquire and recall auditory threat memories. Spiking responses are potentiated for sounds paired with shock (CS+) in the lateral amygdala (LA) and optogenetically identified corticoamygdalar projection neurons, although not in neighboring HO-AC units. Spike- or optogenetically triggered local field potentials reveal enhanced corticofugal-but not corticopetal-functional coupling between HO-AC and LA during threat memory recall that is correlated with pupil-indexed memory strength. We also note robust sound-evoked ACh release that rapidly potentiates for the CS+ in LA but habituates across sessions in HO-AC. These findings highlight a distributed and cooperative plasticity in LA inputs as mice learn to reappraise neutral stimuli as possible threats.
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Affiliation(s)
- Meenakshi M Asokan
- Eaton-Peabody Laboratories, Massachusetts Eye and Ear, Boston, MA 02114, USA; Division of Medical Sciences, Harvard Medical School, Boston, MA 02114, USA.
| | - Yurika Watanabe
- Eaton-Peabody Laboratories, Massachusetts Eye and Ear, Boston, MA 02114, USA
| | - Eyal Y Kimchi
- Eaton-Peabody Laboratories, Massachusetts Eye and Ear, Boston, MA 02114, USA; Department of Neurology, Massachusetts General Hospital, Boston, MA 02114, USA
| | - Daniel B Polley
- Eaton-Peabody Laboratories, Massachusetts Eye and Ear, Boston, MA 02114, USA; Division of Medical Sciences, Harvard Medical School, Boston, MA 02114, USA; Department of Otolaryngology - Head and Neck Surgery, Harvard Medical School, Boston, MA 02114, USA
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5
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Ying R, Hamlette L, Nikoobakht L, Balaji R, Miko N, Caras ML. Organization of orbitofrontal-auditory pathways in the Mongolian gerbil. J Comp Neurol 2023; 531:1459-1481. [PMID: 37477903 PMCID: PMC10529810 DOI: 10.1002/cne.25525] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2023] [Revised: 06/11/2023] [Accepted: 06/26/2023] [Indexed: 07/22/2023]
Abstract
Sound perception is highly malleable, rapidly adjusting to the acoustic environment and behavioral demands. This flexibility is the result of ongoing changes in auditory cortical activity driven by fluctuations in attention, arousal, or prior expectations. Recent work suggests that the orbitofrontal cortex (OFC) may mediate some of these rapid changes, but the anatomical connections between the OFC and the auditory system are not well characterized. Here, we used virally mediated fluorescent tracers to map the projection from OFC to the auditory midbrain, thalamus, and cortex in a classic animal model for auditory research, the Mongolian gerbil (Meriones unguiculatus). We observed no connectivity between the OFC and the auditory midbrain, and an extremely sparse connection between the dorsolateral OFC and higher order auditory thalamic regions. In contrast, we observed a robust connection between the ventral and medial subdivisions of the OFC and the auditory cortex, with a clear bias for secondary auditory cortical regions. OFC axon terminals were found in all auditory cortical lamina but were significantly more concentrated in the infragranular layers. Tissue-clearing and lightsheet microscopy further revealed that auditory cortical-projecting OFC neurons send extensive axon collaterals throughout the brain, targeting both sensory and non-sensory regions involved in learning, decision-making, and memory. These findings provide a more detailed map of orbitofrontal-auditory connections and shed light on the possible role of the OFC in supporting auditory cognition.
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Affiliation(s)
- Rose Ying
- Neuroscience and Cognitive Science Program, University of Maryland, College Park, Maryland, 20742
- Department of Biology, University of Maryland, College Park, Maryland, 20742
- Center for Comparative and Evolutionary Biology of Hearing, University of Maryland, College Park, Maryland, 20742
| | - Lashaka Hamlette
- Department of Biology, University of Maryland, College Park, Maryland, 20742
| | - Laudan Nikoobakht
- Department of Biology, University of Maryland, College Park, Maryland, 20742
| | - Rakshita Balaji
- Department of Biology, University of Maryland, College Park, Maryland, 20742
| | - Nicole Miko
- Department of Biology, University of Maryland, College Park, Maryland, 20742
| | - Melissa L. Caras
- Neuroscience and Cognitive Science Program, University of Maryland, College Park, Maryland, 20742
- Department of Biology, University of Maryland, College Park, Maryland, 20742
- Center for Comparative and Evolutionary Biology of Hearing, University of Maryland, College Park, Maryland, 20742
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6
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Rizzi R, Bidelman GM. Duplex perception reveals brainstem auditory representations are modulated by listeners' ongoing percept for speech. Cereb Cortex 2023; 33:10076-10086. [PMID: 37522248 PMCID: PMC10502779 DOI: 10.1093/cercor/bhad266] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2023] [Revised: 06/27/2023] [Accepted: 07/10/2023] [Indexed: 08/01/2023] Open
Abstract
So-called duplex speech stimuli with perceptually ambiguous spectral cues to one ear and isolated low- versus high-frequency third formant "chirp" to the opposite ear yield a coherent percept supporting their phonetic categorization. Critically, such dichotic sounds are only perceived categorically upon binaural integration. Here, we used frequency-following responses (FFRs), scalp-recorded potentials reflecting phase-locked subcortical activity, to investigate brainstem responses to fused speech percepts and to determine whether FFRs reflect binaurally integrated category-level representations. We recorded FFRs to diotic and dichotic stop-consonants (/da/, /ga/) that either did or did not require binaural fusion to properly label along with perceptually ambiguous sounds without clear phonetic identity. Behaviorally, listeners showed clear categorization of dichotic speech tokens confirming they were heard with a fused, phonetic percept. Neurally, we found FFRs were stronger for categorically perceived speech relative to category-ambiguous tokens but also differentiated phonetic categories for both diotically and dichotically presented speech sounds. Correlations between neural and behavioral data further showed FFR latency predicted the degree to which listeners labeled tokens as "da" versus "ga." The presence of binaurally integrated, category-level information in FFRs suggests human brainstem processing reflects a surprisingly abstract level of the speech code typically circumscribed to much later cortical processing.
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Affiliation(s)
- Rose Rizzi
- Department of Speech, Language, and Hearing Sciences, Indiana University, Bloomington, IN, United States
- Program in Neuroscience, Indiana University, Bloomington, IN, United States
- School of Communication Sciences and Disorders, University of Memphis, Memphis, TN, United States
| | - Gavin M Bidelman
- Department of Speech, Language, and Hearing Sciences, Indiana University, Bloomington, IN, United States
- Program in Neuroscience, Indiana University, Bloomington, IN, United States
- Cognitive Science Program, Indiana University, Bloomington, IN, United States
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7
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Rizzi R, Bidelman GM. Duplex perception reveals brainstem auditory representations are modulated by listeners' ongoing percept for speech. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.05.09.540018. [PMID: 37214801 PMCID: PMC10197666 DOI: 10.1101/2023.05.09.540018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
So-called duplex speech stimuli with perceptually ambiguous spectral cues to one ear and isolated low- vs. high-frequency third formant "chirp" to the opposite ear yield a coherent percept supporting their phonetic categorization. Critically, such dichotic sounds are only perceived categorically upon binaural integration. Here, we used frequency-following responses (FFRs), scalp-recorded potentials reflecting phase-locked subcortical activity, to investigate brainstem responses to fused speech percepts and to determine whether FFRs reflect binaurally integrated category-level representations. We recorded FFRs to diotic and dichotic stop-consonants (/da/, /ga/) that either did or did not require binaural fusion to properly label along with perceptually ambiguous sounds without clear phonetic identity. Behaviorally, listeners showed clear categorization of dichotic speech tokens confirming they were heard with a fused, phonetic percept. Neurally, we found FFRs were stronger for categorically perceived speech relative to category-ambiguous tokens but also differentiated phonetic categories for both diotically and dichotically presented speech sounds. Correlations between neural and behavioral data further showed FFR latency predicted the degree to which listeners labeled tokens as "da" vs. "ga". The presence of binaurally integrated, category-level information in FFRs suggests human brainstem processing reflects a surprisingly abstract level of the speech code typically circumscribed to much later cortical processing.
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Affiliation(s)
- Rose Rizzi
- Department of Speech, Language, and Hearing Sciences, Indiana University, Bloomington, IN, USA
- Program in Neuroscience, Indiana University, Bloomington, IN, USA
- School of Communication Sciences and Disorders, University of Memphis, Memphis, TN, USA
| | - Gavin M. Bidelman
- Department of Speech, Language, and Hearing Sciences, Indiana University, Bloomington, IN, USA
- Program in Neuroscience, Indiana University, Bloomington, IN, USA
- Cognitive Science Program, Indiana University, Bloomington, IN, USA
- School of Communication Sciences and Disorders, University of Memphis, Memphis, TN, USA
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8
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Asokan MM, Watanabe Y, Kimchi EY, Polley DB. Potentiated cholinergic and corticofugal inputs support reorganized sensory processing in the basolateral amygdala during auditory threat acquisition and retrieval. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.01.31.526307. [PMID: 36778308 PMCID: PMC9915656 DOI: 10.1101/2023.01.31.526307] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Reappraising neutral stimuli as environmental threats reflects rapid and discriminative changes in sensory processing within the basolateral amygdala (BLA). To understand how BLA inputs are also reorganized during discriminative threat learning, we performed multi-regional measurements of acetylcholine (ACh) release, single unit spiking, and functional coupling in the mouse BLA and higher-order auditory cortex (HO-AC). During threat memory recall, sounds paired with shock (CS+) elicited relatively higher firing rates in BLA units and optogenetically targeted corticoamygdalar (CAmy) units, though not in neighboring HO-AC units. Functional coupling was potentiated for descending CAmy projections prior to and during CS+ threat memory recall but ascending amygdalocortical coupling was unchanged. During threat acquisition, sound-evoked ACh release was selectively enhanced for the CS+ in BLA but not HO-AC. These findings suggest that phasic cholinergic inputs facilitate discriminative plasticity in the BLA during threat acquisition that is subsequently reinforced through potentiated auditory corticofugal inputs during memory recall.
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Affiliation(s)
- Meenakshi M. Asokan
- Eaton-Peabody Laboratories, Massachusetts Eye and Ear, Boston MA 02114 USA
- Division of Medical Sciences, Harvard Medical School, Boston MA 02114 USA
| | - Yurika Watanabe
- Eaton-Peabody Laboratories, Massachusetts Eye and Ear, Boston MA 02114 USA
| | - Eyal Y. Kimchi
- Eaton-Peabody Laboratories, Massachusetts Eye and Ear, Boston MA 02114 USA
- Department of Neurology, Massachusetts General Hospital, Boston, MA 02114, USA
| | - Daniel B. Polley
- Eaton-Peabody Laboratories, Massachusetts Eye and Ear, Boston MA 02114 USA
- Division of Medical Sciences, Harvard Medical School, Boston MA 02114 USA
- Department of Otolaryngology - Head and Neck Surgery, Harvard Medical School, Boston MA 02114 USA
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9
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Cheng FY, Xu C, Gold L, Smith S. Rapid Enhancement of Subcortical Neural Responses to Sine-Wave Speech. Front Neurosci 2022; 15:747303. [PMID: 34987356 PMCID: PMC8721138 DOI: 10.3389/fnins.2021.747303] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2021] [Accepted: 12/02/2021] [Indexed: 01/15/2023] Open
Abstract
The efferent auditory nervous system may be a potent force in shaping how the brain responds to behaviorally significant sounds. Previous human experiments using the frequency following response (FFR) have shown efferent-induced modulation of subcortical auditory function online and over short- and long-term time scales; however, a contemporary understanding of FFR generation presents new questions about whether previous effects were constrained solely to the auditory subcortex. The present experiment used sine-wave speech (SWS), an acoustically-sparse stimulus in which dynamic pure tones represent speech formant contours, to evoke FFRSWS. Due to the higher stimulus frequencies used in SWS, this approach biased neural responses toward brainstem generators and allowed for three stimuli (/bɔ/, /bu/, and /bo/) to be used to evoke FFRSWSbefore and after listeners in a training group were made aware that they were hearing a degraded speech stimulus. All SWS stimuli were rapidly perceived as speech when presented with a SWS carrier phrase, and average token identification reached ceiling performance during a perceptual training phase. Compared to a control group which remained naïve throughout the experiment, training group FFRSWS amplitudes were enhanced post-training for each stimulus. Further, linear support vector machine classification of training group FFRSWS significantly improved post-training compared to the control group, indicating that training-induced neural enhancements were sufficient to bolster machine learning classification accuracy. These results suggest that the efferent auditory system may rapidly modulate auditory brainstem representation of sounds depending on their context and perception as non-speech or speech.
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Affiliation(s)
- Fan-Yin Cheng
- Department of Speech, Language, and Hearing Sciences, University of Texas at Austin, Austin, TX, United States
| | - Can Xu
- Department of Speech, Language, and Hearing Sciences, University of Texas at Austin, Austin, TX, United States
| | - Lisa Gold
- Department of Speech, Language, and Hearing Sciences, University of Texas at Austin, Austin, TX, United States
| | - Spencer Smith
- Department of Speech, Language, and Hearing Sciences, University of Texas at Austin, Austin, TX, United States
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10
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Qi J, Zhang Z, He N, Liu X, Zhang C, Yan J. Cortical Stimulation Induces Excitatory Postsynaptic Potentials of Inferior Colliculus Neurons in a Frequency-Specific Manner. Front Neural Circuits 2020; 14:591986. [PMID: 33192337 PMCID: PMC7649762 DOI: 10.3389/fncir.2020.591986] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2020] [Accepted: 09/24/2020] [Indexed: 11/30/2022] Open
Abstract
Corticofugal modulation of auditory responses in subcortical nuclei has been extensively studied whereas corticofugal synaptic transmission must still be characterized. This study examined postsynaptic potentials of the corticocollicular system, i.e., the projections from the primary auditory cortex (AI) to the central nucleus of the inferior colliculus (ICc) of the midbrain, in anesthetized C57 mice. We used focal electrical stimulation at the microampere level to activate the AI (ESAI) and in vivo whole-cell current-clamp to record the membrane potentials of ICc neurons. Following the whole-cell patch-clamp recording of 88 ICc neurons, 42 ICc neurons showed ESAI-evoked changes in the membrane potentials. We found that the ESAI induced inhibitory postsynaptic potentials in 6 out of 42 ICc neurons but only when the stimulus current was 96 μA or higher. In the remaining 36 ICc neurons, excitatory postsynaptic potentials (EPSPs) were induced at a much lower stimulus current. The 36 ICc neurons exhibiting EPSPs were categorized into physiologically matched neurons (n = 12) when the characteristic frequencies of the stimulated AI and recorded ICc neurons were similar (≤1 kHz) and unmatched neurons (n = 24) when they were different (>1 kHz). Compared to unmatched neurons, matched neurons exhibited a significantly lower threshold of evoking noticeable EPSP, greater EPSP amplitude, and shorter EPSP latency. Our data allow us to propose that corticocollicular synaptic transmission is primarily excitatory and that synaptic efficacy is dependent on the relationship of the frequency tunings between AI and ICc neurons.
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Affiliation(s)
- Jiyao Qi
- Department of Physiology and Pharmacology, Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada
| | - Zizhen Zhang
- Department of Physiology and Pharmacology, Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada
| | - Na He
- Department of Physiology and Pharmacology, Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada
| | - Xiuping Liu
- Department of Physiology and Pharmacology, Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada
| | - Caseng Zhang
- Department of Physiology and Pharmacology, Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada
| | - Jun Yan
- Department of Physiology and Pharmacology, Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada
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11
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Suga N. Plasticity of the adult auditory system based on corticocortical and corticofugal modulations. Neurosci Biobehav Rev 2020; 113:461-478. [DOI: 10.1016/j.neubiorev.2020.03.021] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2020] [Revised: 03/05/2020] [Accepted: 03/17/2020] [Indexed: 10/24/2022]
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12
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Blackwell JM, Lesicko AMH, Rao W, De Biasi M, Geffen MN. Auditory cortex shapes sound responses in the inferior colliculus. eLife 2020; 9:e51890. [PMID: 32003747 PMCID: PMC7062464 DOI: 10.7554/elife.51890] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2019] [Accepted: 01/31/2020] [Indexed: 12/30/2022] Open
Abstract
The extensive feedback from the auditory cortex (AC) to the inferior colliculus (IC) supports critical aspects of auditory behavior but has not been extensively characterized. Previous studies demonstrated that activity in IC is altered by focal electrical stimulation and pharmacological inactivation of AC, but these methods lack the ability to selectively manipulate projection neurons. We measured the effects of selective optogenetic modulation of cortico-collicular feedback projections on IC sound responses in mice. Activation of feedback increased spontaneous activity and decreased stimulus selectivity in IC, whereas suppression had no effect. To further understand how microcircuits in AC may control collicular activity, we optogenetically modulated the activity of different cortical neuronal subtypes, specifically parvalbumin-positive (PV) and somatostatin-positive (SST) inhibitory interneurons. We found that modulating the activity of either type of interneuron did not affect IC sound-evoked activity. Combined, our results identify that activation of excitatory projections, but not inhibition-driven changes in cortical activity, affects collicular sound responses.
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Affiliation(s)
- Jennifer M Blackwell
- Department of OtorhinolaryngologyUniversity of PennsylvaniaPhiladelphiaUnited States
- Department of Neurobiology and BehaviorStony Brook UniversityStony BrookUnited States
| | - Alexandria MH Lesicko
- Department of OtorhinolaryngologyUniversity of PennsylvaniaPhiladelphiaUnited States
| | - Winnie Rao
- Department of OtorhinolaryngologyUniversity of PennsylvaniaPhiladelphiaUnited States
| | - Mariella De Biasi
- Department of PsychiatryUniversity of PennsylvaniaPhiladelphiaUnited States
- Department of Systems Pharmacology and Experimental TherapeuticsUniversity of PennsylvaniaPhiladelphiaUnited States
- Department of NeuroscienceUniversity of PennsylvaniaPhiladelphiaUnited States
| | - Maria N Geffen
- Department of OtorhinolaryngologyUniversity of PennsylvaniaPhiladelphiaUnited States
- Department of NeuroscienceUniversity of PennsylvaniaPhiladelphiaUnited States
- Department of NeurologyUniversity of PennsylvaniaPhiladelphiaUnited States
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13
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Ito T, Yamamoto R, Furuyama T, Hase K, Kobayasi KI, Hiryu S, Honma S. Three forebrain structures directly inform the auditory midbrain of echolocating bats. Neurosci Lett 2019; 712:134481. [PMID: 31494222 DOI: 10.1016/j.neulet.2019.134481] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2019] [Revised: 09/02/2019] [Accepted: 09/04/2019] [Indexed: 01/10/2023]
Abstract
Echolocating bats emit various types of vocalizations for navigation and communication, and need to pay attention to vocal sounds. Projections from forebrain centers to auditory centers are involved in the attention to vocalizations, with the inferior colliculus (IC) being the main target of the projections. Here, using a retrograde tracer, we demonstrate that three forebrain structures, namely, the medial prefrontal cortex (mPFC), amygdala, and auditory cortex (AC), send direct descending projections to the central nucleus of IC. We found that all three structures projected to the bilateral IC. A comparison of the patterns of retrogradely labeled cells across animals suggests that the ipsilateral AC-IC projection is topographically organized, whereas mPFC-IC or amygdala-IC projections did not show clear topographic organization. Together with evidence from previous studies, these results suggest that three descending projections to the IC form loops between the forebrain and IC to make attention to various vocal sounds.
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Affiliation(s)
- Tetsufumi Ito
- Department of Anatomy, Kanazawa Medical University, Uchinada, Ishikawa, 920-0293, Japan.
| | - Ryo Yamamoto
- Department of Physiology, Kanazawa Medical University, Uchinada, Ishikawa, 920-0293, Japan
| | - Takafumi Furuyama
- Department of Physiology, Kanazawa Medical University, Uchinada, Ishikawa, 920-0293, Japan; Neuroethology and Bioengineering Laboratory, Faculty of Life and Medical Sciences, Doshisha University, Kyotanabe, Kyoto, 610-0394, Japan
| | - Kazuma Hase
- Neuroethology and Bioengineering Laboratory, Faculty of Life and Medical Sciences, Doshisha University, Kyotanabe, Kyoto, 610-0394, Japan
| | - Kohta I Kobayasi
- Neuroethology and Bioengineering Laboratory, Faculty of Life and Medical Sciences, Doshisha University, Kyotanabe, Kyoto, 610-0394, Japan
| | - Shizuko Hiryu
- Neuroethology and Bioengineering Laboratory, Faculty of Life and Medical Sciences, Doshisha University, Kyotanabe, Kyoto, 610-0394, Japan
| | - Satoru Honma
- Department of Anatomy, Kanazawa Medical University, Uchinada, Ishikawa, 920-0293, Japan
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14
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Bajo VM, Nodal FR, Korn C, Constantinescu AO, Mann EO, Boyden ES, King AJ. Silencing cortical activity during sound-localization training impairs auditory perceptual learning. Nat Commun 2019; 10:3075. [PMID: 31300665 PMCID: PMC6625986 DOI: 10.1038/s41467-019-10770-4] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2018] [Accepted: 05/28/2019] [Indexed: 11/09/2022] Open
Abstract
The brain has a remarkable capacity to adapt to changes in sensory inputs and to learn from experience. However, the neural circuits responsible for this flexible processing remain poorly understood. Using optogenetic silencing of ArchT-expressing neurons in adult ferrets, we show that within-trial activity in primary auditory cortex (A1) is required for training-dependent recovery in sound-localization accuracy following monaural deprivation. Because localization accuracy under normal-hearing conditions was unaffected, this highlights a specific role for cortical activity in learning. A1-dependent plasticity appears to leave a memory trace that can be retrieved, facilitating adaptation during a second period of monaural deprivation. However, in ferrets in which learning was initially disrupted by perturbing A1 activity, subsequent optogenetic suppression during training no longer affected localization accuracy when one ear was occluded. After the initial learning phase, the reweighting of spatial cues that primarily underpins this plasticity may therefore occur in A1 target neurons.
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Affiliation(s)
- Victoria M Bajo
- Department of Physiology, Anatomy and Genetics, University of Oxford, Parks Road, Oxford, OX1 3PT, UK.
| | - Fernando R Nodal
- Department of Physiology, Anatomy and Genetics, University of Oxford, Parks Road, Oxford, OX1 3PT, UK
| | - Clio Korn
- Department of Physiology, Anatomy and Genetics, University of Oxford, Parks Road, Oxford, OX1 3PT, UK.,UCSF School of Medicine, San Francisco, CA, 94143-0410, USA
| | - Alexandra O Constantinescu
- Department of Physiology, Anatomy and Genetics, University of Oxford, Parks Road, Oxford, OX1 3PT, UK.,Institute of Cognitive Neuroscience, University College London, London, WC1N 3AR, UK
| | - Edward O Mann
- Department of Physiology, Anatomy and Genetics, University of Oxford, Parks Road, Oxford, OX1 3PT, UK
| | - Edward S Boyden
- Departments of Biological Engineering and Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
| | - Andrew J King
- Department of Physiology, Anatomy and Genetics, University of Oxford, Parks Road, Oxford, OX1 3PT, UK.
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15
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Williamson RS, Polley DB. Parallel pathways for sound processing and functional connectivity among layer 5 and 6 auditory corticofugal neurons. eLife 2019; 8:e42974. [PMID: 30735128 PMCID: PMC6384027 DOI: 10.7554/elife.42974] [Citation(s) in RCA: 56] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2018] [Accepted: 02/06/2019] [Indexed: 11/27/2022] Open
Abstract
Cortical layers (L) 5 and 6 are populated by intermingled cell-types with distinct inputs and downstream targets. Here, we made optogenetically guided recordings from L5 corticofugal (CF) and L6 corticothalamic (CT) neurons in the auditory cortex of awake mice to discern differences in sensory processing and underlying patterns of functional connectivity. Whereas L5 CF neurons showed broad stimulus selectivity with sluggish response latencies and extended temporal non-linearities, L6 CTs exhibited sparse selectivity and rapid temporal processing. L5 CF spikes lagged behind neighboring units and imposed weak feedforward excitation within the local column. By contrast, L6 CT spikes drove robust and sustained activity, particularly in local fast-spiking interneurons. Our findings underscore a duality among sub-cortical projection neurons, where L5 CF units are canonical broadcast neurons that integrate sensory inputs for transmission to distributed downstream targets, while L6 CT neurons are positioned to regulate thalamocortical response gain and selectivity.
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Affiliation(s)
- Ross S Williamson
- Eaton-Peabody LaboratoriesMassachusetts Eye and Ear InfirmaryBostonUnited States
- Department of OtolaryngologyHarvard Medical SchoolBostonUnited States
| | - Daniel B Polley
- Eaton-Peabody LaboratoriesMassachusetts Eye and Ear InfirmaryBostonUnited States
- Department of OtolaryngologyHarvard Medical SchoolBostonUnited States
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16
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Wang H, Shen S, Zheng T, Bi L, Li B, Wang X, Yang Y, Jen PHS. The Role of the Dorsal Nucleus of the Lateral Lemniscus in Shaping the Auditory Response Properties of the Central Nucleus of the Inferior Collicular Neurons in the Albino Mouse. Neuroscience 2018; 390:30-45. [PMID: 30144510 DOI: 10.1016/j.neuroscience.2018.08.015] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2018] [Revised: 08/10/2018] [Accepted: 08/13/2018] [Indexed: 11/17/2022]
Abstract
In the ascending auditory pathway, the central nucleus of the inferior colliculus (IC) receives and integrates excitatory and inhibitory inputs from many bilateral lower auditory nuclei, intrinsic projections within the IC, contralateral IC through the commissure of the IC and from the auditory cortex. All these presynaptic excitatory and inhibitory inputs dynamically shape and modulate the auditory response properties of individual IC neurons. For this reason, acoustic response properties vary among individual IC neurons due to different activity pattern of presynaptic inputs. The present study examines modulation of auditory response properties of IC neurons by combining sound stimulation with focal electrical stimulation of the contralateral dorsal nucleus of the lateral lemniscus (referred to as ESDNLL) in the albino mouse. Brief ESDNLL produces variation (increase or decrease) in the number of impulses, response latency and discharge duration of modulated IC neurons. Additionally, 30-minute short-term ESDNLL alone produces variation in the best frequency (BF) and minimum threshold (MT) of modulated IC neurons. These varied response parameters recover in different manner and time course among individual modulated IC neurons. Possible pathways and neural mechanisms underlying these findings are discussed.
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Affiliation(s)
- Huimei Wang
- College of Special Education, Binzhou Medical College, Yantai, Shandong, People's Republic of China
| | - Shuang Shen
- College of Special Education, Binzhou Medical College, Yantai, Shandong, People's Republic of China
| | - Tihua Zheng
- College of Special Education, Binzhou Medical College, Yantai, Shandong, People's Republic of China
| | - Liyan Bi
- College of Special Education, Binzhou Medical College, Yantai, Shandong, People's Republic of China
| | - Bo Li
- College of Special Education, Binzhou Medical College, Yantai, Shandong, People's Republic of China
| | - Xin Wang
- College of Life Science, Central China Normal University, Wuhan, People's Republic of China
| | - Ying Yang
- College of Special Education, Binzhou Medical College, Yantai, Shandong, People's Republic of China.
| | - Philip H-S Jen
- College of Special Education, Binzhou Medical College, Yantai, Shandong, People's Republic of China; Division of Biological Sciences, University of Missouri-Columbia, Columbia, MO, USA.
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17
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Auditory midbrain coding of statistical learning that results from discontinuous sensory stimulation. PLoS Biol 2018; 16:e2005114. [PMID: 30048446 PMCID: PMC6065201 DOI: 10.1371/journal.pbio.2005114] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2017] [Accepted: 06/21/2018] [Indexed: 11/19/2022] Open
Abstract
Detecting regular patterns in the environment, a process known as statistical
learning, is essential for survival. Neuronal adaptation is a key mechanism in
the detection of patterns that are continuously repeated across short (seconds
to minutes) temporal windows. Here, we found in mice that a subcortical
structure in the auditory midbrain was sensitive to patterns that were repeated
discontinuously, in a temporally sparse manner, across windows of minutes to
hours. Using a combination of behavioral, electrophysiological, and molecular
approaches, we found changes in neuronal response gain that varied in mechanism
with the degree of sound predictability and resulted in changes in frequency
coding. Analysis of population activity (structural tuning) revealed an increase
in frequency classification accuracy in the context of increased overlap in
responses across frequencies. The increase in accuracy and overlap was
paralleled at the behavioral level in an increase in generalization in the
absence of diminished discrimination. Gain modulation was accompanied by changes
in gene and protein expression, indicative of long-term plasticity.
Physiological changes were largely independent of corticofugal feedback, and no
changes were seen in upstream cochlear nucleus responses, suggesting a key role
of the auditory midbrain in sensory gating. Subsequent behavior demonstrated
learning of predictable and random patterns and their importance in auditory
conditioning. Using longer timescales than previously explored, the combined
data show that the auditory midbrain codes statistical learning of temporally
sparse patterns, a process that is critical for the detection of relevant
stimuli in the constant soundscape that the animal navigates through. Some things are learned simply because they are there and not because they are
relevant at that moment in time. This is particularly true of surrounding
sounds, which we process automatically and continuously, detecting their
repetitive patterns or singularities. Learning about rewards and punishment is
typically attributed to cortical structures in the brain and known to occur over
long time windows. Learning of surrounding regularities, on the other hand, is
attributed to subcortical structures and has been shown to occur in seconds. The
brain can, however, also detect the regularity in sounds that are
discontinuously repeated across intervals of minutes and hours. For example, we
learn to identify people by the sound of their steps through an unconscious
process involving repeated but isolated exposures to the coappearance of sound
and person. Here, we show that a subcortical structure, the auditory midbrain,
can code such temporally spread regularities. Neurons in the auditory midbrain
changed their response pattern in mice that heard a fixed tone whenever they
went into one room in the environment they lived in. Learning of temporally
spread sound patterns can, therefore, occur in subcortical structures.
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18
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Brainstem-cortical functional connectivity for speech is differentially challenged by noise and reverberation. Hear Res 2018; 367:149-160. [PMID: 29871826 DOI: 10.1016/j.heares.2018.05.018] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/25/2018] [Revised: 05/18/2018] [Accepted: 05/23/2018] [Indexed: 11/21/2022]
Abstract
Everyday speech perception is challenged by external acoustic interferences that hinder verbal communication. Here, we directly compared how different levels of the auditory system (brainstem vs. cortex) code speech and how their neural representations are affected by two acoustic stressors: noise and reverberation. We recorded multichannel (64 ch) brainstem frequency-following responses (FFRs) and cortical event-related potentials (ERPs) simultaneously in normal hearing individuals to speech sounds presented in mild and moderate levels of noise and reverb. We matched signal-to-noise and direct-to-reverberant ratios to equate the severity between classes of interference. Electrode recordings were parsed into source waveforms to assess the relative contribution of region-specific brain areas [i.e., brainstem (BS), primary auditory cortex (A1), inferior frontal gyrus (IFG)]. Results showed that reverberation was less detrimental to (and in some cases facilitated) the neural encoding of speech compared to additive noise. Inter-regional correlations revealed associations between BS and A1 responses, suggesting subcortical speech representations influence higher auditory-cortical areas. Functional connectivity analyses further showed that directed signaling toward A1 in both feedforward cortico-collicular (BS→A1) and feedback cortico-cortical (IFG→A1) pathways were strong predictors of degraded speech perception and differentiated "good" vs. "poor" perceivers. Our findings demonstrate a functional interplay within the brain's speech network that depends on the form and severity of acoustic interference. We infer that in addition to the quality of neural representations within individual brain regions, listeners' success at the "cocktail party" is modulated based on how information is transferred among subcortical and cortical hubs of the auditory-linguistic network.
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19
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Specialization of the auditory system for the processing of bio-sonar information in the frequency domain: Mustached bats. Hear Res 2018; 361:1-22. [DOI: 10.1016/j.heares.2018.01.012] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/23/2017] [Revised: 01/18/2018] [Accepted: 01/22/2018] [Indexed: 11/20/2022]
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20
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Abstract
Most behaviors in mammals are directly or indirectly guided by prior experience and therefore depend on the ability of our brains to form memories. The ability to form an association between an initially possibly neutral sensory stimulus and its behavioral relevance is essential for our ability to navigate in a changing environment. The formation of a memory is a complex process involving many areas of the brain. In this chapter we review classic and recent work that has shed light on the specific contribution of sensory cortical areas to the formation of associative memories. We discuss synaptic and circuit mechanisms that mediate plastic adaptations of functional properties in individual neurons as well as larger neuronal populations forming topographically organized representations. Furthermore, we describe commonly used behavioral paradigms that are used to study the mechanisms of memory formation. We focus on the auditory modality that is receiving increasing attention for the study of associative memory in rodent model systems. We argue that sensory cortical areas may play an important role for the memory-dependent categorical recognition of previously encountered sensory stimuli.
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Affiliation(s)
- Dominik Aschauer
- Institute of Physiology, Focus Program Translational Neurosciences (FTN), University Medical Center, Johannes Gutenberg University, Mainz, Germany
| | - Simon Rumpel
- Institute of Physiology, Focus Program Translational Neurosciences (FTN), University Medical Center, Johannes Gutenberg University, Mainz, Germany.
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21
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Noise Trauma-Induced Behavioral Gap Detection Deficits Correlate with Reorganization of Excitatory and Inhibitory Local Circuits in the Inferior Colliculus and Are Prevented by Acoustic Enrichment. J Neurosci 2017; 37:6314-6330. [PMID: 28583912 DOI: 10.1523/jneurosci.0602-17.2017] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2017] [Revised: 05/04/2017] [Accepted: 05/14/2017] [Indexed: 01/12/2023] Open
Abstract
Hearing loss leads to a host of cellular and synaptic changes in auditory brain areas that are thought to give rise to auditory perception deficits such as temporal processing impairments, hyperacusis, and tinnitus. However, little is known about possible changes in synaptic circuit connectivity that may underlie these hearing deficits. Here, we show that mild hearing loss as a result of brief noise exposure leads to a pronounced reorganization of local excitatory and inhibitory circuits in the mouse inferior colliculus. The exact nature of these reorganizations correlated with the presence or absence of the animals' impairments in detecting brief sound gaps, a commonly used behavioral sign for tinnitus in animal models. Mice with gap detection deficits (GDDs) showed a shift in the balance of synaptic excitation and inhibition that was present in both glutamatergic and GABAergic neurons, whereas mice without GDDs showed stable excitation-inhibition balances. Acoustic enrichment (AE) with moderate intensity, pulsed white noise immediately after noise trauma prevented both circuit reorganization and GDDs, raising the possibility of using AE immediately after cochlear damage to prevent or alleviate the emergence of central auditory processing deficits.SIGNIFICANCE STATEMENT Noise overexposure is a major cause of central auditory processing disorders, including tinnitus, yet the changes in synaptic connectivity underlying these disorders remain poorly understood. Here, we find that brief noise overexposure leads to distinct reorganizations of excitatory and inhibitory synaptic inputs onto glutamatergic and GABAergic neurons and that the nature of these reorganizations correlates with animals' impairments in detecting brief sound gaps, which is often considered a sign of tinnitus. Acoustic enrichment immediately after noise trauma prevents circuit reorganizations and gap detection deficits, highlighting the potential for using sound therapy soon after cochlear damage to prevent the development of central processing deficits.
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22
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Lockmann ALV, Mourão FAG, Moraes MFD. Auditory fear conditioning modifies steady-state evoked potentials in the rat inferior colliculus. J Neurophysiol 2017; 118:1012-1020. [PMID: 28446582 DOI: 10.1152/jn.00293.2017] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2017] [Accepted: 04/24/2017] [Indexed: 11/22/2022] Open
Abstract
The rat inferior colliculus (IC) is a major midbrain relay for ascending inputs from the auditory brain stem and has been suggested to play a key role in the processing of aversive sounds. Previous studies have demonstrated that auditory fear conditioning (AFC) potentiates transient responses to brief tones in the IC, but it remains unexplored whether AFC modifies responses to sustained periodic acoustic stimulation-a type of response called the steady-state evoked potential (SSEP). Here we used an amplitude-modulated tone-a 10-kHz tone with a sinusoidal amplitude modulation of 53.7 Hz-as the conditioning stimulus (CS) in an AFC protocol (5 CSs per day in 3 consecutive days) while recording local field potentials (LFPs) from the IC. In the preconditioning session (day 1), the CS elicited prominent 53.7-Hz SSEPs. In the training session (day 2), foot shocks occurred at the end of each CS (paired group) or randomized in the inter-CS interval (unpaired group). In the test session (day 3), SSEPs markedly differed from preconditioning in the paired group: in the first two trials the phase to which the SSEP coupled to the CS amplitude envelope shifted ~90°; in the last two trials the SSEP power and the coherence of SSEP with the CS amplitude envelope increased. LFP power decreased in frequency bands other than 53.7 Hz. In the unpaired group, SSEPs did not change in the test compared with preconditioning. Our results show that AFC causes dissociated changes in the phase and power of SSEP in the IC.NEW & NOTEWORTHY Local field potential oscillations in the inferior colliculus follow the amplitude envelope of an amplitude-modulated tone, originating a neural response called the steady-state evoked potential. We show that auditory fear conditioning of an amplitude-modulated tone modifies two parameters of the steady-state evoked potentials in the inferior colliculus: first the phase to which the evoked oscillation couples to the amplitude-modulated tone shifts; subsequently, the evoked oscillation power increases along with its coherence with the amplitude-modulated tone.
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Affiliation(s)
- André Luiz Vieira Lockmann
- Núcleo de Neurociências, Departamento de Fisiologia e Biofísica, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | - Flávio Afonso Gonçalves Mourão
- Núcleo de Neurociências, Departamento de Fisiologia e Biofísica, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | - Marcio Flávio Dutra Moraes
- Núcleo de Neurociências, Departamento de Fisiologia e Biofísica, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
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23
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Maruthy S, Kumar UA, Gnanateja GN. Functional Interplay Between the Putative Measures of Rostral and Caudal Efferent Regulation of Speech Perception in Noise. J Assoc Res Otolaryngol 2017; 18:635-648. [PMID: 28447225 DOI: 10.1007/s10162-017-0623-y] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2016] [Accepted: 03/22/2017] [Indexed: 01/23/2023] Open
Abstract
Efferent modulation has been demonstrated to be very important for speech perception, especially in the presence of noise. We examined the functional relationship between two efferent systems: the rostral and caudal efferent pathways and their individual influences on speech perception in noise. Earlier studies have shown that these two efferent mechanisms were correlated with speech perception in noise. However, previously, these mechanisms were studied in isolation, and their functional relationship with each other was not investigated. We used a correlational design to study the relationship if any, between these two mechanisms in young and old normal hearing individuals. We recorded context-dependent brainstem encoding as an index of rostral efferent function and contralateral suppression of otoacoustic emissions as an index of caudal efferent function in groups with good and poor speech perception in noise. These efferent mechanisms were analysed for their relationship with each other and with speech perception in noise. We found that the two efferent mechanisms did not show any functional relationship. Interestingly, both the efferent mechanisms correlated with speech perception in noise and they even emerged as significant predictors. Based on the data, we posit that the two efferent mechanisms function relatively independently but with a common goal of fine-tuning the afferent input and refining auditory perception in degraded listening conditions.
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Affiliation(s)
- Sandeep Maruthy
- Electrophysiology Laboratory, Department of Audiology, All India Institute of Speech and Hearing, Manasagangothri, Mysore, Karnataka, IN-570006, India
| | - U Ajith Kumar
- Electrophysiology Laboratory, Department of Audiology, All India Institute of Speech and Hearing, Manasagangothri, Mysore, Karnataka, IN-570006, India
| | - G Nike Gnanateja
- Electrophysiology Laboratory, Department of Audiology, All India Institute of Speech and Hearing, Manasagangothri, Mysore, Karnataka, IN-570006, India.
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24
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Modulation of azimuth tuning plasticity in rat primary auditory cortex by medial prefrontal cortex. Neuroscience 2017; 347:36-47. [PMID: 28188851 DOI: 10.1016/j.neuroscience.2017.01.046] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2016] [Revised: 01/11/2017] [Accepted: 01/27/2017] [Indexed: 11/21/2022]
Abstract
Neurons in the primary auditory cortex (A1) of adult animals exhibit short-term plasticity of frequency selectivity and tonotopic organization in behavioral contexts ranging from classical conditioning to attention tasks. However, it is still largely unknown whether short-term plasticity of spatial tuning takes place in A1 of adult animals and whether this spatial turning plasticity in A1 of adults is mediated by medial prefrontal cortex (mPFC) as there are reciprocal connection between mPFC and auditory cortex (AC). In the present study, we used extracellular recordings to test whether azimuth tuning in A1 of anesthetized rats can be reshaped by repeated sound stimuli at neurons' non-preferred azimuth. We also identified whether and how such A1 azimuth tuning plasticity was modulated by the neural activities of mPFC. Our results showed that A1 neurons in adult rats have azimuth tuning plasticity when repeated acoustic stimuli were delivered at the azimuth with a deviation by less than 15° from the best azimuth (BA). The BA shifted toward the exposure azimuth when repeated acoustic stimuli were played for 20-60min and plasticity decayed within one hour. The less the angle deviated from the BA, the shorter exposure time and longer decay time were required to induce azimuth tuning plasticity. Neural activity in mPFC modulated azimuth tuning plasticity of A1 neurons as reflected by the shorter induction time when mPFC was activated by focal electrical stimulation and the longer induction time when mPFC was inactivated by drug application. Our results suggest that spatial location selectivity in A1 neurons remains plastic in mature animals and that short-term plasticity of spatial tuning can be modulated by the neural activities of mPFC.
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25
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Xie Z, Reetzke R, Chandrasekaran B. Stability and plasticity in neural encoding of linguistically relevant pitch patterns. J Neurophysiol 2017; 117:1407-1422. [PMID: 28077662 DOI: 10.1152/jn.00445.2016] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2016] [Revised: 01/09/2017] [Accepted: 01/09/2017] [Indexed: 12/15/2022] Open
Abstract
While lifelong language experience modulates subcortical encoding of pitch patterns, there is emerging evidence that short-term training introduced in adulthood also shapes subcortical pitch encoding. Here we use a cross-language design to examine the stability of language experience-dependent subcortical plasticity over multiple days. We then examine the extent to which behavioral relevance induced by sound-to-category training leads to plastic changes in subcortical pitch encoding in adulthood relative to adolescence, a period of ongoing maturation of subcortical and cortical auditory processing. Frequency-following responses (FFRs), which reflect phase-locked activity from subcortical neural ensembles, were elicited while participants passively listened to pitch patterns reflective of Mandarin tones. In experiment 1, FFRs were recorded across three consecutive days from native Chinese-speaking (n = 10) and English-speaking (n = 10) adults. In experiment 2, FFRs were recorded from native English-speaking adolescents (n = 20) and adults (n = 15) before, during, and immediately after a session of sound-to-category training, as well as a day after training ceased. Experiment 1 demonstrated the stability of language experience-dependent subcortical plasticity in pitch encoding across multiple days of passive exposure to linguistic pitch patterns. In contrast, experiment 2 revealed an enhancement in subcortical pitch encoding that emerged a day after the sound-to-category training, with some developmental differences observed. Taken together, these findings suggest that behavioral relevance is a critical component for the observation of plasticity in the subcortical encoding of pitch.NEW & NOTEWORTHY We examine the timescale of experience-dependent auditory plasticity to linguistically relevant pitch patterns. We find extreme stability in lifelong experience-dependent plasticity. We further demonstrate that subcortical function in adolescents and adults is modulated by a single session of sound-to-category training. Our results suggest that behavioral relevance is a necessary ingredient for neural changes in pitch encoding to be observed throughout human development. These findings contribute to the neurophysiological understanding of long- and short-term experience-dependent modulation of pitch.
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Affiliation(s)
- Zilong Xie
- Department of Communication Sciences and Disorders, The University of Texas at Austin, Austin, Texas
| | - Rachel Reetzke
- Department of Communication Sciences and Disorders, The University of Texas at Austin, Austin, Texas
| | - Bharath Chandrasekaran
- Department of Communication Sciences and Disorders, The University of Texas at Austin, Austin, Texas; .,Department of Psychology, The University of Texas at Austin, Austin, Texas.,Department of Linguistics, The University of Texas at Austin, Austin, Texas.,Institute for Neuroscience, The University of Texas at Austin, Austin, Texas; and.,Institute for Mental Health Research, The University of Texas at Austin, Austin, Texas
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26
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Maggu AR, Liu F, Antoniou M, Wong PCM. Neural Correlates of Indicators of Sound Change in Cantonese: Evidence from Cortical and Subcortical Processes. Front Hum Neurosci 2016; 10:652. [PMID: 28066218 PMCID: PMC5179532 DOI: 10.3389/fnhum.2016.00652] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2016] [Accepted: 12/08/2016] [Indexed: 12/05/2022] Open
Abstract
Across time, languages undergo changes in phonetic, syntactic, and semantic dimensions. Social, cognitive, and cultural factors contribute to sound change, a phenomenon in which the phonetics of a language undergo changes over time. Individuals who misperceive and produce speech in a slightly divergent manner (called innovators) contribute to variability in the society, eventually leading to sound change. However, the cause of variability in these individuals is still unknown. In this study, we examined whether such misperceptions are represented in neural processes of the auditory system. We investigated behavioral, subcortical (via FFR), and cortical (via P300) manifestations of sound change processing in Cantonese, a Chinese language in which several lexical tones are merging. Across the merging categories, we observed a similar gradation of speech perception abilities in both behavior and the brain (subcortical and cortical processes). Further, we also found that behavioral evidence of tone merging correlated with subjects' encoding at the subcortical and cortical levels. These findings indicate that tone-merger categories, that are indicators of sound change in Cantonese, are represented neurophysiologically with high fidelity. Using our results, we speculate that innovators encode speech in a slightly deviant neurophysiological manner, and thus produce speech divergently that eventually spreads across the community and contributes to sound change.
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Affiliation(s)
- Akshay R Maggu
- Department of Linguistics and Modern Languages, The Chinese University of Hong Kong Hong Kong, China
| | - Fang Liu
- School of Psychology and Clinical Language Sciences, University of Reading Reading, UK
| | - Mark Antoniou
- The MARCS Institute for Brain, Behaviour and Development, Western Sydney University Penrith, NSW, Australia
| | - Patrick C M Wong
- Department of Linguistics and Modern Languages, The Chinese University of Hong KongHong Kong, China; Brain and Mind Institute, The Chinese University of Hong KongHong Kong, China; The Chinese University of Hong Kong-Utrecht University Joint Center for Language, Mind and BrainHong Kong, China
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27
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Grossberg S. Towards solving the hard problem of consciousness: The varieties of brain resonances and the conscious experiences that they support. Neural Netw 2016; 87:38-95. [PMID: 28088645 DOI: 10.1016/j.neunet.2016.11.003] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2016] [Revised: 10/21/2016] [Accepted: 11/20/2016] [Indexed: 10/20/2022]
Abstract
The hard problem of consciousness is the problem of explaining how we experience qualia or phenomenal experiences, such as seeing, hearing, and feeling, and knowing what they are. To solve this problem, a theory of consciousness needs to link brain to mind by modeling how emergent properties of several brain mechanisms interacting together embody detailed properties of individual conscious psychological experiences. This article summarizes evidence that Adaptive Resonance Theory, or ART, accomplishes this goal. ART is a cognitive and neural theory of how advanced brains autonomously learn to attend, recognize, and predict objects and events in a changing world. ART has predicted that "all conscious states are resonant states" as part of its specification of mechanistic links between processes of consciousness, learning, expectation, attention, resonance, and synchrony. It hereby provides functional and mechanistic explanations of data ranging from individual spikes and their synchronization to the dynamics of conscious perceptual, cognitive, and cognitive-emotional experiences. ART has reached sufficient maturity to begin classifying the brain resonances that support conscious experiences of seeing, hearing, feeling, and knowing. Psychological and neurobiological data in both normal individuals and clinical patients are clarified by this classification. This analysis also explains why not all resonances become conscious, and why not all brain dynamics are resonant. The global organization of the brain into computationally complementary cortical processing streams (complementary computing), and the organization of the cerebral cortex into characteristic layers of cells (laminar computing), figure prominently in these explanations of conscious and unconscious processes. Alternative models of consciousness are also discussed.
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Affiliation(s)
- Stephen Grossberg
- Center for Adaptive Systems, Boston University, 677 Beacon Street, Boston, MA 02215, USA; Graduate Program in Cognitive and Neural Systems, Departments of Mathematics & Statistics, Psychological & Brain Sciences, and Biomedical Engineering Boston University, 677 Beacon Street, Boston, MA 02215, USA.
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Grossberg S, Kazerounian S. Phoneme restoration and empirical coverage of Interactive Activation and Adaptive Resonance models of human speech processing. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2016; 140:1130. [PMID: 27586743 DOI: 10.1121/1.4946760] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Magnuson [J. Acoust. Soc. Am. 137, 1481-1492 (2015)] makes claims for Interactive Activation (IA) models and against Adaptive Resonance Theory (ART) models of speech perception. Magnuson also presents simulations that claim to show that the TRACE model can simulate phonemic restoration, which was an explanatory target of the cARTWORD ART model. The theoretical analysis and review herein show that these claims are incorrect. More generally, the TRACE and cARTWORD models illustrate two diametrically opposed types of neural models of speech and language. The TRACE model embodies core assumptions with no analog in known brain processes. The cARTWORD model defines a hierarchy of cortical processing regions whose networks embody cells in laminar cortical circuits as part of the paradigm of laminar computing. cARTWORD further develops ART speech and language models that were introduced in the 1970s. It builds upon Item-Order-Rank working memories, which activate learned list chunks that unitize sequences to represent phonemes, syllables, and words. Psychophysical and neurophysiological data support Item-Order-Rank mechanisms and contradict TRACE representations of time, temporal order, silence, and top-down processing that exhibit many anomalous properties, including hallucinations of non-occurring future phonemes. Computer simulations of the TRACE model are presented that demonstrate these failures.
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Affiliation(s)
- Stephen Grossberg
- Departments of Mathematics, Psychology, and Biomedical Engineering, Center for Adaptive Systems, Graduate Program in Cognitive and Neural Systems, Center for Computational Neuroscience and Neural Technology, Boston University, Boston, Massachusetts 02215, USA
| | - Sohrob Kazerounian
- Nuance Communications, Inc., 1 Wayside Road, Burlington, Massachusetts 01803, USA
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Grossberg S. How Does the Cerebral Cortex Work? Development, Learning, Attention, and 3-D Vision by Laminar Circuits of Visual Cortex. ACTA ACUST UNITED AC 2016; 2:47-76. [PMID: 17715598 DOI: 10.1177/1534582303002001003] [Citation(s) in RCA: 81] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
A key goal of behavioral and cognitive neuroscience is to link brain mechanisms to behavioral functions. The present article describes recent progress toward explaining how the visual cortex sees. Visual cortex, like many parts of perceptual and cognitive neocortex, is organized into six main layers of cells, as well as characteristic sublamina. Here it is proposed how these layered circuits help to realize processes of development, learning, perceptual grouping, attention, and 3-D vision through a combination of bottom-up, horizontal, and top-down interactions. A main theme is that the mechanisms which enable development and learning to occur in a stable way imply properties of adult behavior. These results thus begin to unify three fields: infant cortical development, adult cortical neurophysiology and anatomy, and adult visual perception. The identified cortical mechanisms promise to generalize to explain how other perceptual and cognitive processes work.
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Plastic Change in the Auditory Minimum Threshold Induced by Intercollicular Effects in Mice. Neural Plast 2016; 2016:4195391. [PMID: 27057363 PMCID: PMC4739261 DOI: 10.1155/2016/4195391] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2015] [Revised: 11/09/2015] [Accepted: 11/19/2015] [Indexed: 11/17/2022] Open
Abstract
In the auditory pathway, the commissure of the inferior colliculus (IC) interconnects the two ICs on both sides of the dorsal midbrain. This interconnection could mediate an interaction between the two ICs during sound signal processing. The intercollicular effects evoked by focal electric stimulation for 30 min could inhibit or facilitate auditory responses and induce plastic changes in the response minimum threshold (MT) of IC neurons. Changes in MT are dependent on the best frequency (BF) and MT difference. The MT shift is larger in IC neurons with BF differences ≤2 kHz than in those with BF differences >2 kHz. Moreover, MTs that shift toward electrically stimulated IC neurons increase with the increasing MT difference between the two ICs. The shift in MT lasts for a certain period of time and then returns to previous levels within ~150 min. The collicular interactions are either reciprocal or unilateral under alternate stimulating and recording conditions in both ICs. Our results suggest that intercollicular effects may be involved in the acoustic experience-dependent plasticity of the MT of IC neurons.
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Wright BA, Baese-Berk MM, Marrone N, Bradlow AR. Enhancing speech learning by combining task practice with periods of stimulus exposure without practice. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2015; 138:928-37. [PMID: 26328708 PMCID: PMC4545053 DOI: 10.1121/1.4927411] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
Language acquisition typically involves periods when the learner speaks and listens to the new language, and others when the learner is exposed to the language without consciously speaking or listening to it. Adaptation to variants of a native language occurs under similar conditions. Here, speech learning by adults was assessed following a training regimen that mimicked this common situation of language immersion without continuous active language processing. Experiment 1 focused on the acquisition of a novel phonetic category along the voice-onset-time continuum, while Experiment 2 focused on adaptation to foreign-accented speech. The critical training regimens of each experiment involved alternation between periods of practice with the task of phonetic classification (Experiment 1) or sentence recognition (Experiment 2) and periods of stimulus exposure without practice. These practice and exposure periods yielded little to no improvement separately, but alternation between them generated as much or more improvement as did practicing during every period. Practice appears to serve as a catalyst that enables stimulus exposures encountered both during and outside of the practice periods to contribute to quite distinct cases of speech learning. It follows that practice-plus-exposure combinations may tap a general learning mechanism that facilitates language acquisition and speech processing.
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Affiliation(s)
- Beverly A Wright
- Department of Communication Sciences and Disorders and Knowles Hearing Center, Northwestern University, 2240 Campus Drive, Evanston, Illinois 60208, USA
| | - Melissa M Baese-Berk
- Department of Linguistics, 217 Agate Hall, 1290, University of Oregon, Eugene, Oregon 97403, USA
| | - Nicole Marrone
- Department of Speech, Language, and Hearing Sciences, University of Arizona, 1131 E. 2nd Street, Tucson, Arizona 85721, USA
| | - Ann R Bradlow
- Department of Linguistics, Northwestern University, 2016 Sheridan Road, Evanston, Illinois 60208, USA
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Suga N. Neural processing of auditory signals in the time domain: Delay-tuned coincidence detectors in the mustached bat. Hear Res 2015; 324:19-36. [DOI: 10.1016/j.heares.2015.02.008] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/15/2014] [Revised: 02/15/2015] [Accepted: 02/24/2015] [Indexed: 11/25/2022]
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Headley DB, Weinberger NM. Relational associative learning induces cross-modal plasticity in early visual cortex. Cereb Cortex 2015; 25:1306-18. [PMID: 24275832 PMCID: PMC4397573 DOI: 10.1093/cercor/bht325] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Neurobiological theories of memory posit that the neocortex is a storage site of declarative memories, a hallmark of which is the association of two arbitrary neutral stimuli. Early sensory cortices, once assumed uninvolved in memory storage, recently have been implicated in associations between neutral stimuli and reward or punishment. We asked whether links between neutral stimuli also could be formed in early visual or auditory cortices. Rats were presented with a tone paired with a light using a sensory preconditioning paradigm that enabled later evaluation of successful association. Subjects that acquired this association developed enhanced sound evoked potentials in their primary and secondary visual cortices. Laminar recordings localized this potential to cortical Layers 5 and 6. A similar pattern of activation was elicited by microstimulation of primary auditory cortex in the same subjects, consistent with a cortico-cortical substrate of association. Thus, early sensory cortex has the capability to form neutral stimulus associations. This plasticity may constitute a declarative memory trace between sensory cortices.
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Affiliation(s)
- Drew B Headley
- Center for the Neurobiology of Learning and Memory, Department of Neurobiology and Behavior, University of California, Irvine, CA 92697-3800, USA
| | - Norman M Weinberger
- Center for the Neurobiology of Learning and Memory, Department of Neurobiology and Behavior, University of California, Irvine, CA 92697-3800, USA
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Neural Mechanism of Corticofugal Modulation of Tuning Property in Frequency Domain of Bat’s Auditory System. Neural Process Lett 2015. [DOI: 10.1007/s11063-015-9425-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Bidelman GM. Towards an optimal paradigm for simultaneously recording cortical and brainstem auditory evoked potentials. J Neurosci Methods 2015; 241:94-100. [PMID: 25561397 DOI: 10.1016/j.jneumeth.2014.12.019] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2014] [Revised: 12/19/2014] [Accepted: 12/23/2014] [Indexed: 11/17/2022]
Abstract
BACKGROUND Simultaneous recording of brainstem and cortical event-related brain potentials (ERPs) may offer a valuable tool for understanding the early neural transcription of behaviorally relevant sounds and the hierarchy of signal processing operating at multiple levels of the auditory system. To date, dual recordings have been challenged by technological and physiological limitations including different optimal parameters necessary to elicit each class of ERP (e.g., differential adaptation/habitation effects and number of trials to obtain adequate response signal-to-noise ratio). NEW METHOD We investigated a new stimulus paradigm for concurrent recording of the auditory brainstem frequency-following response (FFR) and cortical ERPs. The paradigm is "optimal" in that it uses a clustered stimulus presentation and variable interstimulus interval (ISI) to (i) achieve the most ideal acquisition parameters for eliciting subcortical and cortical responses, (ii) obtain an adequate number of trials to detect each class of response, and (iii) minimize neural adaptation/habituation effects. RESULTS AND COMPARISON WITH EXISTING METHOD Comparison between clustered and traditional (fixed, slow ISI) stimulus paradigms revealed minimal change in amplitude or latencies of either the brainstem FFR or cortical ERP. The clustered paradigm offered over a 3× increase in recording efficiency compared to conventional (fixed ISI presentation) and thus, a more rapid protocol for obtaining dual brainstem-cortical recordings in individual listeners. CONCLUSIONS We infer that faster recording of subcortical and cortical potentials might allow more complete and sensitive testing of neurophysiological function and aid in the differential assessment of auditory function.
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Affiliation(s)
- Gavin M Bidelman
- Institute for Intelligent Systems, University of Memphis, Memphis, TN, USA; School of Communication Sciences & Disorders, University of Memphis, Memphis, TN, USA.
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36
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Offutt SJ, Ryan KJ, Konop AE, Lim HH. Suppression and facilitation of auditory neurons through coordinated acoustic and midbrain stimulation: investigating a deep brain stimulator for tinnitus. J Neural Eng 2014; 11:066001. [PMID: 25307351 PMCID: PMC4244264 DOI: 10.1088/1741-2560/11/6/066001] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
OBJECTIVE The inferior colliculus (IC) is the primary processing center of auditory information in the midbrain and is one site of tinnitus-related activity. One potential option for suppressing the tinnitus percept is through deep brain stimulation via the auditory midbrain implant (AMI), which is designed for hearing restoration and is already being implanted in deaf patients who also have tinnitus. However, to assess the feasibility of AMI stimulation for tinnitus treatment we first need to characterize the functional connectivity within the IC. Previous studies have suggested modulatory projections from the dorsal cortex of the IC (ICD) to the central nucleus of the IC (ICC), though the functional properties of these projections need to be determined. APPROACH In this study, we investigated the effects of electrical stimulation of the ICD on acoustic-driven activity within the ICC in ketamine-anesthetized guinea pigs. MAIN RESULTS We observed ICD stimulation induces both suppressive and facilitatory changes across ICC that can occur immediately during stimulation and remain after stimulation. Additionally, ICD stimulation paired with broadband noise stimulation at a specific delay can induce greater suppressive than facilitatory effects, especially when stimulating in more rostral and medial ICD locations. SIGNIFICANCE These findings demonstrate that ICD stimulation can induce specific types of plastic changes in ICC activity, which may be relevant for treating tinnitus. By using the AMI with electrode sites positioned with the ICD and the ICC, the modulatory effects of ICD stimulation can be tested directly in tinnitus patients.
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Affiliation(s)
- Sarah J. Offutt
- Department of Biomedical Engineering, University of Minnesota, Minneapolis, USA
| | - Kellie J. Ryan
- Department of Biomedical Engineering, University of Minnesota, Minneapolis, USA
| | - Alexander E. Konop
- Department of Biomedical Engineering, University of Minnesota, Minneapolis, USA
| | - Hubert H. Lim
- Department of Biomedical Engineering, University of Minnesota, Minneapolis, USA
- Institute for Translational Neuroscience, University of Minnesota, Minneapolis, USA
- Department of Otolaryngology, Head and Neck Surgery, University of Minnesota, Minneapolis, USA
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Collet G, Leybaert J, Serniclaes W, Deltenre P, Markessis E, Hoonhorst I, Colin C. Les entraînements auditifs : des modifications comportementales aux modifications neurophysiologiques. ANNEE PSYCHOLOGIQUE 2014. [DOI: 10.3917/anpsy.142.0389] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
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Bidelman GM, Villafuerte JW, Moreno S, Alain C. Age-related changes in the subcortical-cortical encoding and categorical perception of speech. Neurobiol Aging 2014; 35:2526-2540. [PMID: 24908166 DOI: 10.1016/j.neurobiolaging.2014.05.006] [Citation(s) in RCA: 134] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2014] [Revised: 04/07/2014] [Accepted: 05/02/2014] [Indexed: 11/18/2022]
Abstract
Aging is associated with declines in auditory processing including speech comprehension abilities. Here, we evaluated both brainstem and cortical speech-evoked brain responses to elucidate how aging impacts the neural transcription and transfer of speech information between functional levels of the auditory nervous system. Behaviorally, older adults showed slower, more variable speech classification performance than younger listeners, which coincided with reduced brainstem amplitude and increased, but delayed, cortical speech-evoked responses. Mild age-related hearing loss showed differential correspondence with neurophysiological responses showing negative (brainstem) and positive (cortical) correlations with brain activity. Spontaneous brain activity, that is, "neural noise," did not differ between older and younger adults. Yet, mutual information and correlations computed between brainstem and cortex revealed higher redundancy (i.e., lower interdependence) in speech information transferred along the auditory pathway implying less neural flexibility in older adults. Results are consistent with the notion that weakened speech encoding in brainstem is overcompensated by increased cortical dysinhibition in the aging brain. Findings suggest aging negatively impacts speech listening abilities by distorting the hierarchy of speech representations, reducing neural flexibility through increased neural redundancy, and ultimately impairing the acoustic-phonetic mapping necessary for robust speech understanding.
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Affiliation(s)
- Gavin M Bidelman
- Institute for Intelligent Systems, University of Memphis, Memphis, TN, USA; School of Communication Sciences & Disorders, University of Memphis, Memphis, TN, USA.
| | - Joshua W Villafuerte
- Rotman Research Institute, Baycrest Centre for Geriatric Care, Toronto, Ontario, Canada; Department of Psychology, University of Toronto, Toronto, Ontario, Canada
| | - Sylvain Moreno
- Rotman Research Institute, Baycrest Centre for Geriatric Care, Toronto, Ontario, Canada; Department of Psychology, University of Toronto, Toronto, Ontario, Canada
| | - Claude Alain
- Rotman Research Institute, Baycrest Centre for Geriatric Care, Toronto, Ontario, Canada; Department of Psychology, University of Toronto, Toronto, Ontario, Canada; Institute of Medical Sciences, University of Toronto, Ontario, Canada
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39
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Skoe E, Chandrasekaran B, Spitzer ER, Wong PC, Kraus N. Human brainstem plasticity: The interaction of stimulus probability and auditory learning. Neurobiol Learn Mem 2014; 109:82-93. [DOI: 10.1016/j.nlm.2013.11.011] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2013] [Revised: 10/14/2013] [Accepted: 11/18/2013] [Indexed: 10/26/2022]
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40
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Moreno S, Bidelman GM. Examining neural plasticity and cognitive benefit through the unique lens of musical training. Hear Res 2014; 308:84-97. [DOI: 10.1016/j.heares.2013.09.012] [Citation(s) in RCA: 118] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/19/2013] [Revised: 09/14/2013] [Accepted: 09/19/2013] [Indexed: 11/30/2022]
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41
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Krizman J, Skoe E, Marian V, Kraus N. Bilingualism increases neural response consistency and attentional control: evidence for sensory and cognitive coupling. BRAIN AND LANGUAGE 2014; 128:34-40. [PMID: 24413593 PMCID: PMC3923605 DOI: 10.1016/j.bandl.2013.11.006] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/10/2013] [Revised: 11/26/2013] [Accepted: 11/29/2013] [Indexed: 05/27/2023]
Abstract
Auditory processing is presumed to be influenced by cognitive processes - including attentional control - in a top-down manner. In bilinguals, activation of both languages during daily communication hones inhibitory skills, which subsequently bolster attentional control. We hypothesize that the heightened attentional demands of bilingual communication strengthens connections between cognitive (i.e., attentional control) and auditory processing, leading to greater across-trial consistency in the auditory evoked response (i.e., neural consistency) in bilinguals. To assess this, we collected passively-elicited auditory evoked responses to the syllable [da] in adolescent Spanish-English bilinguals and English monolinguals and separately obtained measures of attentional control and language ability. Bilinguals demonstrated enhanced attentional control and more consistent brainstem and cortical responses. In bilinguals, but not monolinguals, brainstem consistency tracked with language proficiency and attentional control. We interpret these enhancements in neural consistency as the outcome of strengthened attentional control that emerged from experience communicating in two languages.
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Affiliation(s)
- Jennifer Krizman
- Auditory Neuroscience Laboratory, Evanston, IL, USA(2); Bilingualism and Psycholinguistics Laboratory, Evanston, IL, USA; Department of Communication Sciences, Evanston, IL, USA; Northwestern University, Evanston, IL, USA
| | - Erika Skoe
- Auditory Neuroscience Laboratory, Evanston, IL, USA(2); Department of Communication Sciences, Evanston, IL, USA; Northwestern University, Evanston, IL, USA
| | - Viorica Marian
- Bilingualism and Psycholinguistics Laboratory, Evanston, IL, USA; Department of Communication Sciences, Evanston, IL, USA; Northwestern University, Evanston, IL, USA
| | - Nina Kraus
- Auditory Neuroscience Laboratory, Evanston, IL, USA(2); Department of Communication Sciences, Evanston, IL, USA; Institute for Neuroscience, Evanston, IL, USA; Department of Neurobiology and Physiology, Evanston, IL, USA; Department of Otolaryngology, Evanston, IL, USA; Northwestern University, Evanston, IL, USA.
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42
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Chandrasekaran B, Skoe E, Kraus N. An integrative model of subcortical auditory plasticity. Brain Topogr 2013; 27:539-52. [PMID: 24150692 DOI: 10.1007/s10548-013-0323-9] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2013] [Accepted: 10/05/2013] [Indexed: 11/26/2022]
Abstract
In direct conflict with the concept of auditory brainstem nuclei as passive relay stations for behaviorally-relevant signals, recent studies have demonstrated plasticity of the auditory signal in the brainstem. In this paper we provide an overview of the forms of plasticity evidenced in subcortical auditory regions. We posit an integrative model of auditory plasticity, which argues for a continuous, online modulation of bottom-up signals via corticofugal pathways, based on an algorithm that anticipates and updates incoming stimulus regularities. We discuss the negative implications of plasticity in clinical dysfunction and propose novel methods of eliciting brainstem responses that could specify the biological nature of auditory processing deficits.
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Affiliation(s)
- Bharath Chandrasekaran
- Department of Communication Sciences and Disorders, Center for Perceptual Systems, Institute for Neuroscience, The University of Texas at Austin, Austin, TX, USA,
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43
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Liu X, Wang C, Pan C, Yan J. Physiological Correspondence Dictates Cortical Long-Term Potentiation and Depression by Thalamic Induction. Cereb Cortex 2013; 25:545-53. [DOI: 10.1093/cercor/bht259] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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44
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Luo F, Yan J. Sound-specific plasticity in the primary auditory cortex as induced by the cholinergic pedunculopontine tegmental nucleus. Eur J Neurosci 2013; 37:393-9. [PMID: 23373690 DOI: 10.1111/ejn.12046] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2012] [Revised: 09/23/2012] [Accepted: 10/01/2012] [Indexed: 11/30/2022]
Abstract
Brain cholinergic modulation is essential for learning-induced plasticity of the auditory cortex. The pedunculopontine tegmental nucleus (PPTg) is an important cholinergic nucleus in the brainstem, and appears to be involved in learning and subcortical plasticity. This study confirms the involvement of the PPTg in the plasticity of the auditory cortex in mice. We show here that electrical stimulation of the PPTg paired with a tone induced drastic changes in the frequency tunings of auditory cortical neurons. Importantly, the changes in frequency tuning were highly specific to the frequency of the paired tone; the best frequency of auditory cortical neurons shifted towards the frequency of the paired tone. We further demonstrated that such frequency-specific plasticity was largely eliminated by either thalamic or cortical application of the muscarinic acetylcholine receptor antagonist atropine. Our finding suggests that the PPTg significantly contributes to auditory cortical plasticity via the auditory thalamus and cholinergic basal forebrain.
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Affiliation(s)
- Feng Luo
- Hubei Key Laboratory of Genetic Regulation and Integrative Biology, School of Life Sciences, Central China Normal University, Wuhan, Hubei, China.
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45
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Poremba A, Bigelow J, Rossi B. Processing of communication sounds: contributions of learning, memory, and experience. Hear Res 2013; 305:31-44. [PMID: 23792078 DOI: 10.1016/j.heares.2013.06.005] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/19/2012] [Revised: 05/09/2013] [Accepted: 06/10/2013] [Indexed: 11/17/2022]
Abstract
Abundant evidence from both field and lab studies has established that conspecific vocalizations (CVs) are of critical ecological significance for a wide variety of species, including humans, non-human primates, rodents, and other mammals and birds. Correspondingly, a number of experiments have demonstrated behavioral processing advantages for CVs, such as in discrimination and memory tasks. Further, a wide range of experiments have described brain regions in many species that appear to be specialized for processing CVs. For example, several neural regions have been described in both mammals and birds wherein greater neural responses are elicited by CVs than by comparison stimuli such as heterospecific vocalizations, nonvocal complex sounds, and artificial stimuli. These observations raise the question of whether these regions reflect domain-specific neural mechanisms dedicated to processing CVs, or alternatively, if these regions reflect domain-general neural mechanisms for representing complex sounds of learned significance. Inasmuch as CVs can be viewed as complex combinations of basic spectrotemporal features, the plausibility of the latter position is supported by a large body of literature describing modulated cortical and subcortical representation of a variety of acoustic features that have been experimentally associated with stimuli of natural behavioral significance (such as food rewards). Herein, we review a relatively small body of existing literature describing the roles of experience, learning, and memory in the emergence of species-typical neural representations of CVs and auditory system plasticity. In both songbirds and mammals, manipulations of auditory experience as well as specific learning paradigms are shown to modulate neural responses evoked by CVs, either in terms of overall firing rate or temporal firing patterns. In some cases, CV-sensitive neural regions gradually acquire representation of non-CV stimuli with which subjects have training and experience. These results parallel literature in humans describing modulation of responses in face-sensitive neural regions through learning and experience. Thus, although many questions remain, the available evidence is consistent with the notion that CVs may acquire distinct neural representation through domain-general mechanisms for representing complex auditory objects that are of learned importance to the animal. This article is part of a Special Issue entitled "Communication Sounds and the Brain: New Directions and Perspectives".
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Affiliation(s)
- Amy Poremba
- University of Iowa, Dept. of Psychology, Div. Behavioral & Cognitive Neuroscience, E11 SSH, Iowa City, IA 52242, USA; University of Iowa, Neuroscience Program, Iowa City, IA 52242, USA.
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Gnanateja GN, Ranjan R, Firdose H, Sinha SK, Maruthy S. Acoustic basis of context dependent brainstem encoding of speech. Hear Res 2013; 304:28-32. [PMID: 23792077 DOI: 10.1016/j.heares.2013.06.002] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/28/2012] [Revised: 05/28/2013] [Accepted: 06/03/2013] [Indexed: 11/15/2022]
Abstract
The newfound context dependent brainstem encoding of speech is evidence of online regularity detection and modulation of the sub-cortical responses. We studied the influence of spectral structure of the contextual stimulus on context dependent encoding of speech at the brainstem, in an attempt to understand the acoustic basis for this effect. Fourteen normal hearing adults participated in a randomized true experimental design in whom brainstem responses were recorded. Brainstem responses for a high pass filtered /da/ in the context of syllables, that either had same or different spectral structure were compared with each other. The findings suggest that spectral structure is one of the parameters which cue the context dependent sub-cortical encoding of speech. Interestingly, the results also revealed that, brainstem can encode pitch even with negligible acoustic information below the second formant frequency.
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Affiliation(s)
- G Nike Gnanateja
- Department of Audiology, All India Institute of Speech and Hearing, Manasagangothri, Mysore 570006, Karnataka, India.
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Kim H, Bao S. Experience-dependent overrepresentation of ultrasonic vocalization frequencies in the rat primary auditory cortex. J Neurophysiol 2013; 110:1087-96. [PMID: 23741037 DOI: 10.1152/jn.00230.2013] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Cortical sensory representation is highly adaptive to the environment, and prevalent or behaviorally important stimuli are often overrepresented. One class of such stimuli is species-specific vocalizations. Rats vocalize in the ultrasonic range >30 kHz, but cortical representation of this frequency range has not been systematically examined. We recorded in vivo cortical electrophysiological responses to ultrasonic pure-tone pips, natural ultrasonic vocalizations, and pitch-shifted vocalizations to assess how rats represent this ethologically relevant frequency range. We find that nearly 40% of the primary auditory cortex (AI) represents an octave-wide band of ultrasonic vocalization frequencies (UVFs; 32-64 kHz) compared with <20% for other octave bands <32 kHz. These UVF neurons respond preferentially and reliably to ultrasonic vocalizations. The UVF overrepresentation matures in the cortex before it develops in the central nucleus of inferior colliculus, suggesting a cortical origin and corticofugal influences. Furthermore, the development of cortical UVF overrepresentation depends on early acoustic experience. These results indicate that natural sensory experience causes large-scale cortical map reorganization and improves representations of species-specific vocalizations.
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Affiliation(s)
- Heesoo Kim
- Helen Wills Neuroscience Institute, University of California, Berkeley, CA 94720-3190, USA
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Markovitz CD, Tang TT, Lim HH. Tonotopic and localized pathways from primary auditory cortex to the central nucleus of the inferior colliculus. Front Neural Circuits 2013; 7:77. [PMID: 23641201 PMCID: PMC3635033 DOI: 10.3389/fncir.2013.00077] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2012] [Accepted: 04/04/2013] [Indexed: 11/13/2022] Open
Abstract
Descending projections from the cortex to subcortical structures are critical for auditory plasticity, including the ability for central neurons to adjust their frequency tuning to relevant and meaningful stimuli. We show that focal electrical stimulation of primary auditory cortex in guinea pigs produces excitatory responses in the central nucleus of the inferior colliculus (CNIC) with two tonotopic patterns: a narrow tuned pattern that is consistent with previous findings showing direct frequency-aligned projections; and a broad tuned pattern in which the auditory cortex can influence multiple frequency regions. Moreover, excitatory responses could be elicited in the caudomedial portion along the isofrequency laminae of the CNIC but not in the rostrolateral portion. This descending organization may underlie or contribute to the ability of the auditory cortex to induce changes in frequency tuning of subcortical neurons as shown extensively in previous studies.
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Affiliation(s)
- Craig D Markovitz
- Department of Biomedical Engineering, University of Minnesota Minneapolis, MN, USA
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Blundon JA, Zakharenko SS. Presynaptic gating of postsynaptic synaptic plasticity: a plasticity filter in the adult auditory cortex. Neuroscientist 2013; 19:465-78. [PMID: 23558179 DOI: 10.1177/1073858413482983] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Sensory cortices can not only detect and analyze incoming sensory information but can also undergo plastic changes while learning behaviorally important sensory cues. This experience-dependent cortical plasticity is essential for shaping and modifying neuronal circuits to perform computations of multiple, previously unknown sensations, the adaptive process that is believed to underlie perceptual learning. Intensive efforts to identify the mechanisms of cortical plasticity have provided several important clues; however, the exact cellular sites and mechanisms within the intricate neuronal networks that underlie cortical plasticity have yet to be elucidated. In this review, we present several parallels between cortical plasticity in the auditory cortex and recently discovered mechanisms of synaptic plasticity gating at thalamocortical projections that provide the main input to sensory cortices. Striking similarities between the features and mechanisms of thalamocortical synaptic plasticity and those of experience-dependent cortical plasticity in the auditory cortex, especially in terms of regulation of an early critical period, point to thalamocortical projections as an important locus of plasticity in sensory cortices.
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Affiliation(s)
- Jay A Blundon
- Department of Development Neurobiology, St. Jude Children's Research Hospital, Memphis, TN 38105-2794, USA
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50
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Cheng L, Mei HX, Tang J, Fu ZY, Jen PHS, Chen QC. Bilateral collicular interaction: modulation of auditory signal processing in frequency domain. Neuroscience 2013; 235:27-39. [PMID: 23321542 DOI: 10.1016/j.neuroscience.2013.01.011] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2012] [Revised: 12/30/2012] [Accepted: 01/08/2013] [Indexed: 10/27/2022]
Abstract
In the ascending auditory pathway, the inferior colliculus (IC) receives and integrates excitatory and inhibitory inputs from a variety of lower auditory nuclei, intrinsic projections within the IC, contralateral IC through the commissure of the IC and the auditory cortex. All these connections make the IC a major center for subcortical temporal and spectral integration of auditory information. In this study, we examine bilateral collicular interaction in the modulation of frequency-domain signal processing of mice using electrophysiological recording and focal electrical stimulation. Focal electrical stimulation of neurons in one IC produces widespread inhibition and focused facilitation of responses of neurons in the other IC. This bilateral collicular interaction decreases the response magnitude and lengthens the response latency of inhibited IC neurons but produces an opposite effect on the response of facilitated IC neurons. In the frequency domain, the focal electrical stimulation of one IC sharpens or expands the frequency tuning curves (FTCs) of neurons in the other IC to improve frequency sensitivity and the frequency response range. The focal electrical stimulation also produces a shift in the best frequency (BF) of modulated IC (ICMdu) neurons toward that of electrically stimulated IC (ICES) neurons. The degree of bilateral collicular interaction is dependent upon the difference in the BF between the ICES neurons and ICMdu neurons. These data suggest that bilateral collicular interaction is a part of dynamic acoustic signal processing that adjusts and improves signal processing as well as reorganizes collicular representation of signal parameters according to the acoustic experience.
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Affiliation(s)
- L Cheng
- School of Life Sciences & Hubei Key Lab of Genetic Regulation and Integrative Biology, Central China Normal University, Wuhan 430079, China
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