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Hu C, Hasenstaub AR, Schreiner CE. Basic Properties of Coordinated Neuronal Ensembles in the Auditory Thalamus. J Neurosci 2024; 44:e1729232024. [PMID: 38561224 PMCID: PMC11079962 DOI: 10.1523/jneurosci.1729-23.2024] [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: 09/13/2023] [Revised: 03/04/2024] [Accepted: 03/11/2024] [Indexed: 04/04/2024] Open
Abstract
Coordinated neuronal activity has been identified to play an important role in information processing and transmission in the brain. However, current research predominantly focuses on understanding the properties and functions of neuronal coordination in hippocampal and cortical areas, leaving subcortical regions relatively unexplored. In this study, we use single-unit recordings in female Sprague Dawley rats to investigate the properties and functions of groups of neurons exhibiting coordinated activity in the auditory thalamus-the medial geniculate body (MGB). We reliably identify coordinated neuronal ensembles (cNEs), which are groups of neurons that fire synchronously, in the MGB. cNEs are shown not to be the result of false-positive detections or by-products of slow-state oscillations in anesthetized animals. We demonstrate that cNEs in the MGB have enhanced information-encoding properties over individual neurons. Their neuronal composition is stable between spontaneous and evoked activity, suggesting limited stimulus-induced ensemble dynamics. These MGB cNE properties are similar to what is observed in cNEs in the primary auditory cortex (A1), suggesting that ensembles serve as a ubiquitous mechanism for organizing local networks and play a fundamental role in sensory processing within the brain.
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Affiliation(s)
- Congcong Hu
- John & Edward Coleman Memorial Laboratory, University of California-San Francisco, San Francisco, California 94158
- Neuroscience Graduate Program, University of California-San Francisco, San Francisco, California 94158
- Department of Otolaryngology-Head and Neck Surgery, University of California-San Francisco, San Francisco, California 94158
| | - Andrea R Hasenstaub
- John & Edward Coleman Memorial Laboratory, University of California-San Francisco, San Francisco, California 94158
- Neuroscience Graduate Program, University of California-San Francisco, San Francisco, California 94158
- Department of Otolaryngology-Head and Neck Surgery, University of California-San Francisco, San Francisco, California 94158
| | - Christoph E Schreiner
- John & Edward Coleman Memorial Laboratory, University of California-San Francisco, San Francisco, California 94158
- Neuroscience Graduate Program, University of California-San Francisco, San Francisco, California 94158
- Department of Otolaryngology-Head and Neck Surgery, University of California-San Francisco, San Francisco, California 94158
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2
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Schultheiβ H, Zulfiqar I, Verardo C, Jolivet RB, Moerel M. Modelling homeostatic plasticity in the auditory cortex results in neural signatures of tinnitus. Neuroimage 2023; 271:119987. [PMID: 36940510 DOI: 10.1016/j.neuroimage.2023.119987] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2022] [Revised: 12/23/2022] [Accepted: 02/25/2023] [Indexed: 03/22/2023] Open
Abstract
Tinnitus is a clinical condition where a sound is perceived without an external sound source. Homeostatic plasticity (HSP), serving to increase neural activity as compensation for the reduced input to the auditory pathway after hearing loss, has been proposed as a mechanism underlying tinnitus. In support, animal models of tinnitus show evidence of increased neural activity after hearing loss, including increased spontaneous and sound-driven firing rate, as well as increased neural noise throughout the auditory processing pathway. Bridging these findings to human tinnitus, however, has proven to be challenging. Here we implement hearing loss-induced HSP in a Wilson-Cowan Cortical Model of the auditory cortex to predict how homeostatic principles operating at the microscale translate to the meso- to macroscale accessible through human neuroimaging. We observed HSP-induced response changes in the model that were previously proposed as neural signatures of tinnitus, but that have also been reported as correlates of hearing loss and hyperacusis. As expected, HSP increased spontaneous and sound-driven responsiveness in hearing-loss affected frequency channels of the model. We furthermore observed evidence of increased neural noise and the appearance of spatiotemporal modulations in neural activity, which we discuss in light of recent human neuroimaging findings. Our computational model makes quantitative predictions that require experimental validation, and may thereby serve as the basis of future human studies of hearing loss, tinnitus, and hyperacusis.
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Affiliation(s)
- Hannah Schultheiβ
- Department of Cognitive Neuroscience, Faculty of Psychology and Neuroscience, Maastricht University, Maastricht, the Netherlands; Master Systems Biology, Faculty of Science and Engineering, Maastricht University, Maastricht, the Netherlands
| | - Isma Zulfiqar
- Department of Cognitive Neuroscience, Faculty of Psychology and Neuroscience, Maastricht University, Maastricht, the Netherlands
| | - Claudio Verardo
- Maastricht Centre for Systems Biology, Maastricht University, Maastricht, the Netherlands; The BioRobotics Institute and Department of Excellence in Robotics and AI, Scuola Superiore Sant'Anna, Pisa, Italy
| | - Renaud B Jolivet
- Maastricht Centre for Systems Biology, Maastricht University, Maastricht, the Netherlands
| | - Michelle Moerel
- Department of Cognitive Neuroscience, Faculty of Psychology and Neuroscience, Maastricht University, Maastricht, the Netherlands; Maastricht Brain Imaging Center (MBIC), Maastricht, the Netherlands; Maastricht Centre for Systems Biology, Maastricht University, Maastricht, the Netherlands.
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3
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Lage-Castellanos A, De Martino F, Ghose GM, Gulban OF, Moerel M. Selective attention sharpens population receptive fields in human auditory cortex. Cereb Cortex 2022; 33:5395-5408. [PMID: 36336333 PMCID: PMC10152083 DOI: 10.1093/cercor/bhac427] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2022] [Revised: 10/03/2022] [Accepted: 10/04/2022] [Indexed: 11/09/2022] Open
Abstract
Abstract
Selective attention enables the preferential processing of relevant stimulus aspects. Invasive animal studies have shown that attending a sound feature rapidly modifies neuronal tuning throughout the auditory cortex. Human neuroimaging studies have reported enhanced auditory cortical responses with selective attention. To date, it remains unclear how the results obtained with functional magnetic resonance imaging (fMRI) in humans relate to the electrophysiological findings in animal models. Here we aim to narrow the gap between animal and human research by combining a selective attention task similar in design to those used in animal electrophysiology with high spatial resolution ultra-high field fMRI at 7 Tesla. Specifically, human participants perform a detection task, whereas the probability of target occurrence varies with sound frequency. Contrary to previous fMRI studies, we show that selective attention resulted in population receptive field sharpening, and consequently reduced responses, at the attended sound frequencies. The difference between our results to those of previous fMRI studies supports the notion that the influence of selective attention on auditory cortex is diverse and may depend on context, stimulus, and task.
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Affiliation(s)
- Agustin Lage-Castellanos
- Department of Cognitive Neuroscience , Faculty of Psychology and Neuroscience, , 6200 MD, Maastricht , The Netherlands
- Maastricht University , Faculty of Psychology and Neuroscience, , 6200 MD, Maastricht , The Netherlands
- Maastricht Brain Imaging Center (MBIC) , 6200 MD, Maastricht , The Netherlands
- Department of NeuroInformatics, Cuban Neuroscience Center , Havana City 11600 , Cuba
| | - Federico De Martino
- Department of Cognitive Neuroscience , Faculty of Psychology and Neuroscience, , 6200 MD, Maastricht , The Netherlands
- Maastricht University , Faculty of Psychology and Neuroscience, , 6200 MD, Maastricht , The Netherlands
- Maastricht Brain Imaging Center (MBIC) , 6200 MD, Maastricht , The Netherlands
- Center for Magnetic Resonance Research , Department of Radiology, , Minneapolis, MN 55455 , United States
- University of Minnesota , Department of Radiology, , Minneapolis, MN 55455 , United States
| | - Geoffrey M Ghose
- Center for Magnetic Resonance Research , Department of Radiology, , Minneapolis, MN 55455 , United States
- University of Minnesota , Department of Radiology, , Minneapolis, MN 55455 , United States
| | | | - Michelle Moerel
- Department of Cognitive Neuroscience , Faculty of Psychology and Neuroscience, , 6200 MD, Maastricht , The Netherlands
- Maastricht University , Faculty of Psychology and Neuroscience, , 6200 MD, Maastricht , The Netherlands
- Maastricht Brain Imaging Center (MBIC) , 6200 MD, Maastricht , The Netherlands
- Maastricht Centre for Systems Biology, Maastricht University , 6200 MD, Maastricht , The Netherlands
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4
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Distinct integration of spectrally complex sounds in mouse primary auditory cortices. Hear Res 2022; 417:108455. [DOI: 10.1016/j.heares.2022.108455] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/30/2021] [Revised: 01/07/2022] [Accepted: 01/26/2022] [Indexed: 11/21/2022]
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5
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Chen F, Takemoto M, Nishimura M, Tomioka R, Song WJ. Postnatal development of subfields in the core region of the mouse auditory cortex. Hear Res 2020; 400:108138. [PMID: 33285368 DOI: 10.1016/j.heares.2020.108138] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/27/2020] [Revised: 11/24/2020] [Accepted: 11/25/2020] [Indexed: 10/22/2022]
Abstract
The core region of the rodent auditory cortex has two subfields: the primary auditory area (A1) and the anterior auditory field (AAF). Although the postnatal development of A1 has been studied in several mammalian species, few studies have been conducted on the postnatal development of AAF. Using a voltage-sensitive-dye-based imaging method, we examined and compared the postnatal development of AAF and A1 in mice from postnatal day 11 (P11) to P40. We focused on the postnatal development of tonotopy, the relative position between A1 and AAF, and the properties of tone-evoked responses in the subfields. Tone-evoked responses in the mouse auditory cortex were first observed at P12, and tonotopy was found in both A1 and AAF at this age. Quantification of tonotopy using the cortical magnification factor (CMF; octave difference per unit cortical distance) revealed a rapid change from P12 to P14 in both A1 and AAF, and a stable level from P14. A similar time course of postnatal development was found for the distance between the 4 kHz site in A1 and AAF, the distance between the 16 kHz site in A1 and AAF, and the angle between the frequency axis of A1 and AAF. The maximum amplitude and rise time of tone-evoked signals in both A1 and AAF showed no significant change from P12 to P40, but the latency of the responses to both the 4 kHz and 16 kHz tones decreased during this period, with a more rapid decrease in the latency to 16 kHz tones in both subfields. The duration of responses evoked by 4 kHz tones in both A1 and AAF showed no significant postnatal change, but the duration of responses to 16 kHz tones decreased exponentially in both subfields. The cortical area activated by 4 kHz tones in AAF was always larger than that in A1 at all ages (P12-P40). Our results demonstrated that A1 and AAF developed in parallel postnatally, showing a rapid maturation of tonotopy, slow maturation of response latency and response duration, and a dorsal-to-ventral order (high-frequency site to low-frequency site) of functional maturation.
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Affiliation(s)
- Feifan Chen
- Department of Sensory and Cognitive Physiology, Graduate School of Medical Sciences, Kumamoto University, Japan; Program for Leading Graduate Schools HIGO Program, Kumamoto University, Kumamoto, Japan
| | - Makoto Takemoto
- Department of Sensory and Cognitive Physiology, Graduate School of Medical Sciences, Kumamoto University, Japan
| | - Masataka Nishimura
- Department of Sensory and Cognitive Physiology, Graduate School of Medical Sciences, Kumamoto University, Japan
| | - Ryohei Tomioka
- Department of Sensory and Cognitive Physiology, Graduate School of Medical Sciences, Kumamoto University, Japan
| | - Wen-Jie Song
- Department of Sensory and Cognitive Physiology, Graduate School of Medical Sciences, Kumamoto University, Japan; Program for Leading Graduate Schools HIGO Program, Kumamoto University, Kumamoto, Japan; Center for Metabolic Regulation of Healthy Aging, Faculty of Life Sciences, Kumamoto University, Kumamoto 860-8556, Japan.
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6
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Gaucher Q, Panniello M, Ivanov AZ, Dahmen JC, King AJ, Walker KM. Complexity of frequency receptive fields predicts tonotopic variability across species. eLife 2020; 9:53462. [PMID: 32420865 PMCID: PMC7269667 DOI: 10.7554/elife.53462] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2019] [Accepted: 05/18/2020] [Indexed: 12/17/2022] Open
Abstract
Primary cortical areas contain maps of sensory features, including sound frequency in primary auditory cortex (A1). Two-photon calcium imaging in mice has confirmed the presence of these global tonotopic maps, while uncovering an unexpected local variability in the stimulus preferences of individual neurons in A1 and other primary regions. Here we show that local heterogeneity of frequency preferences is not unique to rodents. Using two-photon calcium imaging in layers 2/3, we found that local variance in frequency preferences is equivalent in ferrets and mice. Neurons with multipeaked frequency tuning are less spatially organized than those tuned to a single frequency in both species. Furthermore, we show that microelectrode recordings may describe a smoother tonotopic arrangement due to a sampling bias towards neurons with simple frequency tuning. These results help explain previous inconsistencies in cortical topography across species and recording techniques.
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Affiliation(s)
- Quentin Gaucher
- Department of Physiology, Anatomy & Genetics, University of Oxford, Oxford, United Kingdom
| | - Mariangela Panniello
- Department of Physiology, Anatomy & Genetics, University of Oxford, Oxford, United Kingdom
| | - Aleksandar Z Ivanov
- Department of Physiology, Anatomy & Genetics, University of Oxford, Oxford, United Kingdom
| | - Johannes C Dahmen
- Department of Physiology, Anatomy & Genetics, University of Oxford, Oxford, United Kingdom
| | - Andrew J King
- Department of Physiology, Anatomy & Genetics, University of Oxford, Oxford, United Kingdom
| | - Kerry Mm Walker
- Department of Physiology, Anatomy & Genetics, University of Oxford, Oxford, United Kingdom
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7
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Shih JY, Yuan K, Atencio CA, Schreiner CE. Distinct Manifestations of Cooperative, Multidimensional Stimulus Representations in Different Auditory Forebrain Stations. Cereb Cortex 2020; 30:3130-3147. [PMID: 32047882 DOI: 10.1093/cercor/bhz299] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Classic spectrotemporal receptive fields (STRFs) for auditory neurons are usually expressed as a single linear filter representing a single encoded stimulus feature. Multifilter STRF models represent the stimulus-response relationship of primary auditory cortex (A1) neurons more accurately because they can capture multiple stimulus features. To determine whether multifilter processing is unique to A1, we compared the utility of single-filter versus multifilter STRF models in the medial geniculate body (MGB), anterior auditory field (AAF), and A1 of ketamine-anesthetized cats. We estimated STRFs using both spike-triggered average (STA) and maximally informative dimension (MID) methods. Comparison of basic filter properties of first maximally informative dimension (MID1) and second maximally informative dimension (MID2) in the 3 stations revealed broader spectral integration of MID2s in MGBv and A1 as opposed to AAF. MID2 peak latency was substantially longer than for STAs and MID1s in all 3 stations. The 2-filter MID model captured more information and yielded better predictions in many neurons from all 3 areas but disproportionately more so in AAF and A1 compared with MGBv. Significantly, information-enhancing cooperation between the 2 MIDs was largely restricted to A1 neurons. This demonstrates significant differences in how these 3 forebrain stations process auditory information, as expressed in effective and synergistic multifilter processing.
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Affiliation(s)
- Jonathan Y Shih
- Department of Otolaryngology-Head and Neck Surgery, Coleman Memorial Laboratory, UCSF Center for Integrative Neuroscience, University of California, San Francisco, CA 94158-0444, USA
| | - Kexin Yuan
- Department of Otolaryngology-Head and Neck Surgery, Coleman Memorial Laboratory, UCSF Center for Integrative Neuroscience, University of California, San Francisco, CA 94158-0444, USA.,Department of Biomedical Engineering, School of Medicine, Tsinghua University, Beijing, 100084, China
| | - Craig A Atencio
- Department of Otolaryngology-Head and Neck Surgery, Coleman Memorial Laboratory, UCSF Center for Integrative Neuroscience, University of California, San Francisco, CA 94158-0444, USA
| | - Christoph E Schreiner
- Department of Otolaryngology-Head and Neck Surgery, Coleman Memorial Laboratory, UCSF Center for Integrative Neuroscience, University of California, San Francisco, CA 94158-0444, USA
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8
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Nakata S, Takemoto M, Song WJ. Differential cortical and subcortical projection targets of subfields in the core region of mouse auditory cortex. Hear Res 2020; 386:107876. [PMID: 31881516 DOI: 10.1016/j.heares.2019.107876] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/27/2019] [Revised: 12/17/2019] [Accepted: 12/20/2019] [Indexed: 11/15/2022]
Abstract
The core region of the rodent auditory cortex has two areas: the primary auditory area (A1) and the anterior auditory field (AAF). However, the functional difference between these areas is unclear. To elucidate this issue, here we studied the projections from A1 and AAF in mice using adeno-associated virus (AAV) vectors expressing either a green fluorescent protein or a red fluorescent protein. After mapping A1 and AAF using optical imaging, we injected a distinct AAV vector into each of the two fields at a frequency-matched high-frequency location. We found that A1 and AAF projected commonly to virtually all target areas examined, but each field had its own preference for projection targets. Frontal and parietal regions were the major cortical targets: in the frontal cortex, A1 and AAF showed dominant projections to the anterior cingulate cortex Cg1 and the secondary motor cortex (M2), respectively; in the parietal cortex, A1 and AAF exhibited dense projections to the medial secondary visual cortex and the posterior parietal cortex (PPC), respectively. Although M2 and PPC received considerable input from A1 as well, A1 innervated the medial part whereas AAF innervated the lateral part of these cortical regions. A1 also projected to the orbitofrontal cortex, while AAF also projected to the primary somatosensory cortex and insular auditory cortex. As for subcortical projections, A1 and AAF projected to a common ventromedial region in the caudal striatum with a comparable strength; they also both projected to the medial geniculate body and the inferior colliculus, innervating common and distinct divisions of the nuclei. A1 also projected to visual subcortical structures, such as the superior colliculus and the lateral posterior nucleus of the thalamus, where fibres from AAF were sparse. Our results demonstrate the preference of A1 and AAF for cortical and subcortical targets, and for divisions in individual target. The preference of A1 and AAF for sensory-related structures suggest a role for A1 in providing auditory information for audio-visual association at both the cortical and subcortical level, and a distinct role of AAF in providing auditory information for association with somatomotor information in the cortex.
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Affiliation(s)
- Shiro Nakata
- Department of Sensory and Cognitive Physiology, Graduate School of Medical Sciences, Kumamoto University, Kumamoto, 860-8556, Japan
| | - Makoto Takemoto
- Department of Sensory and Cognitive Physiology, Graduate School of Medical Sciences, Kumamoto University, Kumamoto, 860-8556, Japan
| | - Wen-Jie Song
- Department of Sensory and Cognitive Physiology, Graduate School of Medical Sciences, Kumamoto University, Kumamoto, 860-8556, Japan; Center for Metabolic Regulation of Healthy Aging, Faculty of Life Sciences, Kumamoto University, Kumamoto, 860-8556, Japan.
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9
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Distinct processing of tone offset in two primary auditory cortices. Sci Rep 2019; 9:9581. [PMID: 31270350 PMCID: PMC6610078 DOI: 10.1038/s41598-019-45952-z] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2019] [Accepted: 06/19/2019] [Indexed: 11/08/2022] Open
Abstract
In the rodent auditory system, the primary cortex is subdivided into two regions, both receiving direct inputs from the auditory thalamus: the primary auditory cortex (A1) and the anterior auditory field (AAF). Although neurons in the two regions display different response properties, like response latency, firing threshold or tuning bandwidth, it is still not clear whether they process sound in a distinct way. Using in vivo electrophysiological recordings in the mouse auditory cortex, we found that AAF neurons have significantly stronger responses to tone offset than A1 neurons. AAF neurons also display faster and more transient responses than A1 neurons. Additionally, offset responses in AAF – unlike in A1, increase with sound duration. Local field potential (LFP) and laminar analyses suggest that the differences in sound responses between these two primary cortices are both of subcortical and intracortical origin. These results emphasize the potentially critical role of AAF for temporal processing. Our study reveals a distinct role of two primary auditory cortices in tone processing and highlights the complexity of sound encoding at the cortical level.
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10
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Zhu S, Allitt B, Samuel A, Lui L, Rosa MGP, Rajan R. Sensitivity to Vocalization Pitch in the Caudal Auditory Cortex of the Marmoset: Comparison of Core and Belt Areas. Front Syst Neurosci 2019; 13:5. [PMID: 30774587 PMCID: PMC6367263 DOI: 10.3389/fnsys.2019.00005] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2018] [Accepted: 01/14/2019] [Indexed: 11/13/2022] Open
Abstract
Based on anatomical connectivity and basic response characteristics, primate auditory cortex is divided into a central core surrounded by belt and parabelt regions. The encoding of pitch, a prototypical element of sound identity, has been studied in primary auditory cortex (A1) but little is known about how it is encoded and represented beyond A1. The caudal auditory belt and parabelt cortical fields process spatial information but also contain information on non-spatial aspects of sounds. In this study, we examined neuronal responses in these areas to pitch-varied marmoset vocalizations, to derive the consequent representation of pitch in these regions and the potential underlying mechanisms, to compare to the encoding and representation of pitch of the same sounds in A1. With respect to response patterns to the vocalizations, neurons in caudal medial belt (CM) showed similar short-latency and short-duration response patterns to A1, but caudal lateral belt (CL) neurons at the same hierarchical level and caudal parabelt (CPB) neurons at a higher hierarchical level showed delayed or much delayed response onset and prolonged response durations. With respect to encoding of pitch, neurons in all cortical fields showed sensitivity to variations in the vocalization pitch either through modulation of spike-count or of first spike-latency. The utility of the encoding mechanism differed between fields: pitch sensitivity was reliably represented by spike-count variations in A1 and CM, while first spike-latency variation was better for encoding pitch in CL and CPB. In summary, our data show that (a) the traditionally-defined belt area CM is functionally very similar to A1 with respect to the representation and encoding of complex naturalistic sounds, (b) the CL belt area, at the same hierarchical level as CM, and the CPB area, at a higher hierarchical level, have very different response patterns and appear to use different pitch-encoding mechanisms, and (c) caudal auditory fields, proposed to be specialized for encoding spatial location, can also contain robust representations of sound identity.
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Affiliation(s)
- Shuyu Zhu
- Biomedicine Discovery Institute and Department of Physiology, Monash University, Clayton, VIC, Australia.,Australian Research Council, Centre of Excellence in Integrative Brain Function, Clayton, VIC, Australia
| | - Benjamin Allitt
- Biomedicine Discovery Institute and Department of Physiology, Monash University, Clayton, VIC, Australia
| | - Anil Samuel
- Biomedicine Discovery Institute and Department of Physiology, Monash University, Clayton, VIC, Australia
| | - Leo Lui
- Biomedicine Discovery Institute and Department of Physiology, Monash University, Clayton, VIC, Australia.,Australian Research Council, Centre of Excellence in Integrative Brain Function, Clayton, VIC, Australia
| | - Marcello G P Rosa
- Biomedicine Discovery Institute and Department of Physiology, Monash University, Clayton, VIC, Australia.,Australian Research Council, Centre of Excellence in Integrative Brain Function, Clayton, VIC, Australia
| | - Ramesh Rajan
- Biomedicine Discovery Institute and Department of Physiology, Monash University, Clayton, VIC, Australia.,Australian Research Council, Centre of Excellence in Integrative Brain Function, Clayton, VIC, Australia
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11
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Excitatory effects of the primary auditory cortex on the sound-evoked responses in the ipsilateral anterior auditory field in rat. Neuroscience 2017; 361:157-166. [PMID: 28827180 DOI: 10.1016/j.neuroscience.2017.08.019] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2017] [Revised: 08/08/2017] [Accepted: 08/09/2017] [Indexed: 11/22/2022]
Abstract
In the neocortex, interaction and cooperation between different areas are important for information processing, which also applies to different areas within one sensory modality. In the temporal cortex of rodents and cats, both the primary auditory cortex (A1) and the anterior auditory field (AAF) have tonotopicity but with a mirrored frequency gradient. However, whether and how A1 modulates the responses in AAF is largely unknown. Here, we functionally identified the locations of A1 and AAF in rats and used an optogenetic approach to manipulate the activity of A1 in vivo. We found that activation of A1 axon terminals in AAF did not change AAF responses, but activating A1 neuronal cell bodies could increase the sound-evoked responses in AAF, as well as decrease the intensity threshold and broaden the frequency bandwidth, while suppressing A1 could cause the opposite effects. Our results suggested that A1 could modulate the general excitability of AAF through indirect pathways, which provides a potential relationship between these two parallel auditory ascending pathways.
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12
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Moerel M, De Martino F, Kemper VG, Schmitter S, Vu AT, Uğurbil K, Formisano E, Yacoub E. Sensitivity and specificity considerations for fMRI encoding, decoding, and mapping of auditory cortex at ultra-high field. Neuroimage 2017; 164:18-31. [PMID: 28373123 DOI: 10.1016/j.neuroimage.2017.03.063] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2016] [Revised: 12/18/2016] [Accepted: 03/29/2017] [Indexed: 01/05/2023] Open
Abstract
Following rapid technological advances, ultra-high field functional MRI (fMRI) enables exploring correlates of neuronal population activity at an increasing spatial resolution. However, as the fMRI blood-oxygenation-level-dependent (BOLD) contrast is a vascular signal, the spatial specificity of fMRI data is ultimately determined by the characteristics of the underlying vasculature. At 7T, fMRI measurement parameters determine the relative contribution of the macro- and microvasculature to the acquired signal. Here we investigate how these parameters affect relevant high-end fMRI analyses such as encoding, decoding, and submillimeter mapping of voxel preferences in the human auditory cortex. Specifically, we compare a T2* weighted fMRI dataset, obtained with 2D gradient echo (GE) EPI, to a predominantly T2 weighted dataset obtained with 3D GRASE. We first investigated the decoding accuracy based on two encoding models that represented different hypotheses about auditory cortical processing. This encoding/decoding analysis profited from the large spatial coverage and sensitivity of the T2* weighted acquisitions, as evidenced by a significantly higher prediction accuracy in the GE-EPI dataset compared to the 3D GRASE dataset for both encoding models. The main disadvantage of the T2* weighted GE-EPI dataset for encoding/decoding analyses was that the prediction accuracy exhibited cortical depth dependent vascular biases. However, we propose that the comparison of prediction accuracy across the different encoding models may be used as a post processing technique to salvage the spatial interpretability of the GE-EPI cortical depth-dependent prediction accuracy. Second, we explored the mapping of voxel preferences. Large-scale maps of frequency preference (i.e., tonotopy) were similar across datasets, yet the GE-EPI dataset was preferable due to its larger spatial coverage and sensitivity. However, submillimeter tonotopy maps revealed biases in assigned frequency preference and selectivity for the GE-EPI dataset, but not for the 3D GRASE dataset. Thus, a T2 weighted acquisition is recommended if high specificity in tonotopic maps is required. In conclusion, different fMRI acquisitions were better suited for different analyses. It is therefore critical that any sequence parameter optimization considers the eventual intended fMRI analyses and the nature of the neuroscience questions being asked.
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Affiliation(s)
- Michelle Moerel
- Center for Magnetic Resonance Research, Department of Radiology, University of Minnesota, Minneapolis, USA; Maastricht Centre for Systems Biology, Maastricht University, Maastricht, The Netherlands; Department of Cognitive Neuroscience, Faculty of Psychology and Neuroscience, Maastricht University, Maastricht, The Netherlands; Maastricht Brain Imaging Center (MBIC), Maastricht, The Netherlands.
| | - Federico De Martino
- Center for Magnetic Resonance Research, Department of Radiology, University of Minnesota, Minneapolis, USA; Department of Cognitive Neuroscience, Faculty of Psychology and Neuroscience, Maastricht University, Maastricht, The Netherlands; Maastricht Brain Imaging Center (MBIC), Maastricht, The Netherlands.
| | - Valentin G Kemper
- Department of Cognitive Neuroscience, Faculty of Psychology and Neuroscience, Maastricht University, Maastricht, The Netherlands; Maastricht Brain Imaging Center (MBIC), Maastricht, The Netherlands.
| | - Sebastian Schmitter
- Center for Magnetic Resonance Research, Department of Radiology, University of Minnesota, Minneapolis, USA; Department of Biomedical Magnetic Resonance, Physikalisch-Technische Bundesanstalt, Berlin, Germany.
| | - An T Vu
- Center for Magnetic Resonance Research, Department of Radiology, University of Minnesota, Minneapolis, USA; Helen Wills Neuroscience Institute, University of California, Berkeley, CA, USA; Advanced MRI Technologies, Sebastopol, CA, USA.
| | - Kâmil Uğurbil
- Center for Magnetic Resonance Research, Department of Radiology, University of Minnesota, Minneapolis, USA.
| | - Elia Formisano
- Maastricht Centre for Systems Biology, Maastricht University, Maastricht, The Netherlands; Department of Cognitive Neuroscience, Faculty of Psychology and Neuroscience, Maastricht University, Maastricht, The Netherlands; Maastricht Brain Imaging Center (MBIC), Maastricht, The Netherlands.
| | - Essa Yacoub
- Center for Magnetic Resonance Research, Department of Radiology, University of Minnesota, Minneapolis, USA.
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Quantitative map of multiple auditory cortical regions with a stereotaxic fine-scale atlas of the mouse brain. Sci Rep 2016; 6:22315. [PMID: 26924462 PMCID: PMC4770424 DOI: 10.1038/srep22315] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2015] [Accepted: 02/12/2016] [Indexed: 11/08/2022] Open
Abstract
Optical imaging studies have recently revealed the presence of multiple auditory cortical regions in the mouse brain. We have previously demonstrated, using flavoprotein fluorescence imaging, at least six regions in the mouse auditory cortex, including the anterior auditory field (AAF), primary auditory cortex (AI), the secondary auditory field (AII), dorsoanterior field (DA), dorsomedial field (DM), and dorsoposterior field (DP). While multiple regions in the visual cortex and somatosensory cortex have been annotated and consolidated in recent brain atlases, the multiple auditory cortical regions have not yet been presented from a coronal view. In the current study, we obtained regional coordinates of the six auditory cortical regions of the C57BL/6 mouse brain and illustrated these regions on template coronal brain slices. These results should reinforce the existing mouse brain atlases and support future studies in the auditory cortex.
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Bizley JK, Bajo VM, Nodal FR, King AJ. Cortico-Cortical Connectivity Within Ferret Auditory Cortex. J Comp Neurol 2015; 523:2187-210. [PMID: 25845831 PMCID: PMC4737260 DOI: 10.1002/cne.23784] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2014] [Revised: 03/29/2015] [Accepted: 04/01/2015] [Indexed: 12/29/2022]
Abstract
Despite numerous studies of auditory cortical processing in the ferret (Mustela putorius), very little is known about the connections between the different regions of the auditory cortex that have been characterized cytoarchitectonically and physiologically. We examined the distribution of retrograde and anterograde labeling after injecting tracers into one or more regions of ferret auditory cortex. Injections of different tracers at frequency‐matched locations in the core areas, the primary auditory cortex (A1) and anterior auditory field (AAF), of the same animal revealed the presence of reciprocal connections with overlapping projections to and from discrete regions within the posterior pseudosylvian and suprasylvian fields (PPF and PSF), suggesting that these connections are frequency specific. In contrast, projections from the primary areas to the anterior dorsal field (ADF) on the anterior ectosylvian gyrus were scattered and non‐overlapping, consistent with the non‐tonotopic organization of this field. The relative strength of the projections originating in each of the primary fields differed, with A1 predominantly targeting the posterior bank fields PPF and PSF, which in turn project to the ventral posterior field, whereas AAF projects more heavily to the ADF, which then projects to the anteroventral field and the pseudosylvian sulcal cortex. These findings suggest that parallel anterior and posterior processing networks may exist, although the connections between different areas often overlap and interactions were present at all levels. J. Comp. Neurol. 523:2187–2210, 2015. © 2015 Wiley Periodicals, Inc.
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Affiliation(s)
- Jennifer K Bizley
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, OX1 3PT, United Kingdom.,Ear Institute, University College London, London, WC1X 8EE, United Kingdom
| | - Victoria M Bajo
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, OX1 3PT, United Kingdom
| | | | - Andrew J King
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, OX1 3PT, United Kingdom
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15
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Washington SD, Tillinghast JS. Conjugating time and frequency: hemispheric specialization, acoustic uncertainty, and the mustached bat. Front Neurosci 2015; 9:143. [PMID: 25926767 PMCID: PMC4410141 DOI: 10.3389/fnins.2015.00143] [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: 11/24/2014] [Accepted: 04/07/2015] [Indexed: 11/23/2022] Open
Abstract
A prominent hypothesis of hemispheric specialization for human speech and music states that the left and right auditory cortices (ACs) are respectively specialized for precise calculation of two canonically-conjugate variables: time and frequency. This spectral-temporal asymmetry does not account for sex, brain-volume, or handedness, and is in opposition to closed-system hypotheses that restrict this asymmetry to humans. Mustached bats have smaller brains, but greater ethological pressures to develop such a spectral-temporal asymmetry, than humans. Using the Heisenberg-Gabor Limit (i.e., the mathematical basis of the spectral-temporal asymmetry) to frame mustached bat literature, we show that recent findings in bat AC (1) support the notion that hemispheric specialization for speech and music is based on hemispheric differences in temporal and spectral resolution, (2) discredit closed-system, handedness, and brain-volume theories, (3) underscore the importance of sex differences, and (4) provide new avenues for phonological research.
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Affiliation(s)
- Stuart D Washington
- Center for Functional and Molecular Imaging, Georgetown University Medical Center Washington, DC, USA ; Department of Neurology, Georgetown University Medical Center Washington, DC, USA ; Center for Neuroscience Research, Children's National Medical Center Washington, DC, USA
| | - John S Tillinghast
- Department of Mathematics and Statistics, American University Washington, DC, USA ; Department of Statistics, The George Washington University Washington, DC, USA
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Malmierca MS, Anderson LA, Antunes FM. The cortical modulation of stimulus-specific adaptation in the auditory midbrain and thalamus: a potential neuronal correlate for predictive coding. Front Syst Neurosci 2015; 9:19. [PMID: 25805974 PMCID: PMC4353371 DOI: 10.3389/fnsys.2015.00019] [Citation(s) in RCA: 77] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2014] [Accepted: 02/03/2015] [Indexed: 02/02/2023] Open
Abstract
To follow an ever-changing auditory scene, the auditory brain is continuously creating a representation of the past to form expectations about the future. Unexpected events will produce an error in the predictions that should “trigger” the network’s response. Indeed, neurons in the auditory midbrain, thalamus and cortex, respond to rarely occurring sounds while adapting to frequently repeated ones, i.e., they exhibit stimulus specific adaptation (SSA). SSA cannot be explained solely by intrinsic membrane properties, but likely involves the participation of the network. Thus, SSA is envisaged as a high order form of adaptation that requires the influence of cortical areas. However, present research supports the hypothesis that SSA, at least in its simplest form (i.e., to frequency deviants), can be transmitted in a bottom-up manner through the auditory pathway. Here, we briefly review the underlying neuroanatomy of the corticofugal projections before discussing state of the art studies which demonstrate that SSA present in the medial geniculate body (MGB) and inferior colliculus (IC) is not inherited from the cortex but can be modulated by the cortex via the corticofugal pathways. By modulating the gain of neurons in the thalamus and midbrain, the auditory cortex (AC) would refine SSA subcortically, preventing irrelevant information from reaching the cortex.
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Affiliation(s)
- Manuel S Malmierca
- Auditory Neuroscience Laboratory, Institute of Neuroscience of Castilla y León (INCyL), University of Salamanca Salamanca, Spain ; Faculty of Medicine, Department of Cell Biology and Pathology, University of Salamanca Salamanca, Spain
| | - Lucy A Anderson
- Auditory Neuroscience Laboratory, Institute of Neuroscience of Castilla y León (INCyL), University of Salamanca Salamanca, Spain
| | - Flora M Antunes
- Auditory Neuroscience Laboratory, Institute of Neuroscience of Castilla y León (INCyL), University of Salamanca Salamanca, Spain
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Tsukano H, Horie M, Bo T, Uchimura A, Hishida R, Kudoh M, Takahashi K, Takebayashi H, Shibuki K. Delineation of a frequency-organized region isolated from the mouse primary auditory cortex. J Neurophysiol 2015; 113:2900-20. [PMID: 25695649 PMCID: PMC4416634 DOI: 10.1152/jn.00932.2014] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2014] [Accepted: 02/17/2015] [Indexed: 01/30/2023] Open
Abstract
The primary auditory cortex (AI) is the representative recipient of information from the ears in the mammalian cortex. However, the delineation of the AI is still controversial in a mouse. Recently, it was reported, using optical imaging, that two distinct areas of the AI, located ventrally and dorsally, are activated by high-frequency tones, whereas only one area is activated by low-frequency tones. Here, we show that the dorsal high-frequency area is an independent region that is separated from the rest of the AI. We could visualize the two distinct high-frequency areas using flavoprotein fluorescence imaging, as reported previously. SMI-32 immunolabeling revealed that the dorsal region had a different cytoarchitectural pattern from the rest of the AI. Specifically, the ratio of SMI-32-positive pyramidal neurons to nonpyramidal neurons was larger in the dorsal high-frequency area than the rest of the AI. We named this new region the dorsomedial field (DM). Retrograde tracing showed that neurons projecting to the DM were localized in the rostral part of the ventral division of the medial geniculate body with a distinct frequency organization, where few neurons projected to the AI. Furthermore, the responses of the DM to ultrasonic courtship songs presented by males were significantly greater in females than in males; in contrast, there was no sex difference in response to artificial pure tones. Our findings offer a basic outline on the processing of ultrasonic vocal information on the basis of the precisely subdivided, multiple frequency-organized auditory cortex map in mice.
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Affiliation(s)
- Hiroaki Tsukano
- Department of Neurophysiology, Brain Research Institute, Niigata University, Niigata, Japan;
| | - Masao Horie
- Division of Neurobiology and Anatomy, Graduate School of Medicine and Dental Sciences, Niigata University, Niigata, Japan
| | - Takeshi Bo
- Department of Neurophysiology, Brain Research Institute, Niigata University, Niigata, Japan
| | - Arikuni Uchimura
- KOKORO-Biology Group, Laboratories for Integrated Biology, Graduate School of Frontier Biosciences, Osaka University, Osaka, Japan
| | - Ryuichi Hishida
- Department of Neurophysiology, Brain Research Institute, Niigata University, Niigata, Japan
| | - Masaharu Kudoh
- Department of Physiology, Teikyo University School of Medicine, Tokyo, Japan; and
| | - Kuniyuki Takahashi
- Department of Otolaryngology, Graduate School of Medicine and Dental Sciences, Niigata University, Niigata, Japan
| | - Hirohide Takebayashi
- Division of Neurobiology and Anatomy, Graduate School of Medicine and Dental Sciences, Niigata University, Niigata, Japan
| | - Katsuei Shibuki
- Department of Neurophysiology, Brain Research Institute, Niigata University, Niigata, Japan
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Carrasco A, Brown TA, Lomber SG. Spectral and Temporal Acoustic Features Modulate Response Irregularities within Primary Auditory Cortex Columns. PLoS One 2014; 9:e114550. [PMID: 25494365 PMCID: PMC4262427 DOI: 10.1371/journal.pone.0114550] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2014] [Accepted: 11/05/2014] [Indexed: 11/18/2022] Open
Abstract
Assemblies of vertically connected neurons in the cerebral cortex form information processing units (columns) that participate in the distribution and segregation of sensory signals. Despite well-accepted models of columnar architecture, functional mechanisms of inter-laminar communication remain poorly understood. Hence, the purpose of the present investigation was to examine the effects of sensory information features on columnar response properties. Using acute recording techniques, extracellular response activity was collected from the right hemisphere of eight mature cats (felis catus). Recordings were conducted with multichannel electrodes that permitted the simultaneous acquisition of neuronal activity within primary auditory cortex columns. Neuronal responses to simple (pure tones), complex (noise burst and frequency modulated sweeps), and ecologically relevant (con-specific vocalizations) acoustic signals were measured. Collectively, the present investigation demonstrates that despite consistencies in neuronal tuning (characteristic frequency), irregularities in discharge activity between neurons of individual A1 columns increase as a function of spectral (signal complexity) and temporal (duration) acoustic variations.
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Affiliation(s)
- Andres Carrasco
- Cerebral Systems Laboratory, University of Western Ontario, London, Ontario, Canada
- Brain and Mind Institute, University of Western Ontario, London, Ontario, Canada
- Department of Physiology and Pharmacology, University of Western Ontario, London, Ontario, Canada
| | - Trecia A. Brown
- Cerebral Systems Laboratory, University of Western Ontario, London, Ontario, Canada
- Brain and Mind Institute, University of Western Ontario, London, Ontario, Canada
- Department of Physiology and Pharmacology, University of Western Ontario, London, Ontario, Canada
| | - Stephen G. Lomber
- Cerebral Systems Laboratory, University of Western Ontario, London, Ontario, Canada
- Brain and Mind Institute, University of Western Ontario, London, Ontario, Canada
- Department of Physiology and Pharmacology, University of Western Ontario, London, Ontario, Canada
- Department of Psychology, University of Western Ontario, London, Ontario, Canada
- National Centre for Audiology, University of Western Ontario, London, Ontario, Canada
- * E-mail:
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Saldeitis K, Happel MF, Ohl FW, Scheich H, Budinger E. Anatomy of the auditory thalamocortical system in the mongolian gerbil: Nuclear origins and cortical field-, layer-, and frequency-specificities. J Comp Neurol 2014; 522:2397-430. [DOI: 10.1002/cne.23540] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2013] [Revised: 01/03/2014] [Accepted: 01/10/2014] [Indexed: 01/24/2023]
Affiliation(s)
- Katja Saldeitis
- Department of Auditory Learning & Speech; Leibniz Institute for Neurobiology; D-39118 Magdeburg Germany
| | - Max F.K. Happel
- Department of Systems Physiology of Learning; Leibniz Institute for Neurobiology; D-39118 Magdeburg Germany
- Institute of Biology, Otto-von-Guericke University; D-39120 Magdeburg Germany
| | - Frank W. Ohl
- Department of Systems Physiology of Learning; Leibniz Institute for Neurobiology; D-39118 Magdeburg Germany
- Institute of Biology, Otto-von-Guericke University; D-39120 Magdeburg Germany
- Center for Behavioral Brain Sciences; Magdeburg Universitätsplatz 2, D-39106 Germany
| | - Henning Scheich
- Department of Auditory Learning & Speech; Leibniz Institute for Neurobiology; D-39118 Magdeburg Germany
- Center for Behavioral Brain Sciences; Magdeburg Universitätsplatz 2, D-39106 Germany
| | - Eike Budinger
- Department of Auditory Learning & Speech; Leibniz Institute for Neurobiology; D-39118 Magdeburg Germany
- Clinic of Neurology; Otto-von-Guericke-University Magdeburg; D-39120 Magdeburg Germany
- Center for Behavioral Brain Sciences; Magdeburg Universitätsplatz 2, D-39106 Germany
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20
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Takemoto M, Hasegawa K, Nishimura M, Song WJ. The insular auditory field receives input from the lemniscal subdivision of the auditory thalamus in mice. J Comp Neurol 2014; 522:1373-89. [DOI: 10.1002/cne.23491] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2013] [Revised: 09/30/2013] [Accepted: 10/07/2013] [Indexed: 12/19/2022]
Affiliation(s)
- Makoto Takemoto
- Department of Sensory and Cognitive Physiology; Graduate School of Medical Sciences; Kumamoto University; umamoto 860-8556 Japan
| | - Kayoko Hasegawa
- Department of Sensory and Cognitive Physiology; Graduate School of Medical Sciences; Kumamoto University; umamoto 860-8556 Japan
| | - Masataka Nishimura
- Department of Sensory and Cognitive Physiology; Graduate School of Medical Sciences; Kumamoto University; umamoto 860-8556 Japan
| | - Wen-Jie Song
- Department of Sensory and Cognitive Physiology; Graduate School of Medical Sciences; Kumamoto University; umamoto 860-8556 Japan
- Program for Leading Graduate Schools; Health Life Science: Interdisciplinary and Globally Oriented (HIGO) Program, Kumamoto University; Kumamoto 860-8556 Japan
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21
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Joachimsthaler B, Uhlmann M, Miller F, Ehret G, Kurt S. Quantitative analysis of neuronal response properties in primary and higher-order auditory cortical fields of awake house mice (Mus musculus). Eur J Neurosci 2014; 39:904-918. [PMID: 24506843 PMCID: PMC4264920 DOI: 10.1111/ejn.12478] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2013] [Revised: 12/10/2013] [Accepted: 12/11/2013] [Indexed: 12/01/2022]
Abstract
Because of its great genetic potential, the mouse (Mus musculus) has become a popular model species for studies on hearing and sound processing along the auditory pathways. Here, we present the first comparative study on the representation of neuronal response parameters to tones in primary and higher-order auditory cortical fields of awake mice. We quantified 12 neuronal properties of tone processing in order to estimate similarities and differences of function between the fields, and to discuss how far auditory cortex (AC) function in the mouse is comparable to that in awake monkeys and cats. Extracellular recordings were made from 1400 small clusters of neurons from cortical layers III/IV in the primary fields AI (primary auditory field) and AAF (anterior auditory field), and the higher-order fields AII (second auditory field) and DP (dorsoposterior field). Field specificity was shown with regard to spontaneous activity, correlation between spontaneous and evoked activity, tone response latency, sharpness of frequency tuning, temporal response patterns (occurrence of phasic responses, phasic-tonic responses, tonic responses, and off-responses), and degree of variation between the characteristic frequency (CF) and the best frequency (BF) (CF-BF relationship). Field similarities were noted as significant correlations between CFs and BFs, V-shaped frequency tuning curves, similar minimum response thresholds and non-monotonic rate-level functions in approximately two-thirds of the neurons. Comparative and quantitative analyses showed that the measured response characteristics were, to various degrees, susceptible to influences of anesthetics. Therefore, studies of neuronal responses in the awake AC are important in order to establish adequate relationships between neuronal data and auditory perception and acoustic response behavior.
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Affiliation(s)
- Bettina Joachimsthaler
- Institute of Neurobiology, University of UlmInstitute of Neurobiology 89081 Ulm, Germany
- Systems Neurophysiology, Department of Cognitive Neurology, Werner Reichardt Centre for Integrative Neuroscience, Hertie Institute for Clinical Brain Research, University of TübingenTübingen, Germany
| | - Michaela Uhlmann
- Institute of Neurobiology, University of UlmInstitute of Neurobiology 89081 Ulm, Germany
| | - Frank Miller
- Institute of Neurobiology, University of UlmInstitute of Neurobiology 89081 Ulm, Germany
| | - Günter Ehret
- Institute of Neurobiology, University of UlmInstitute of Neurobiology 89081 Ulm, Germany
| | - Simone Kurt
- Institute of Neurobiology, University of UlmInstitute of Neurobiology 89081 Ulm, Germany
- Cluster of Excellence “Hearing4all”, Institute of Audioneurotechnology and Hannover Medical School, Department of Experimental Otology, ENT Clinics30625 Hannover, Germany
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22
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Fallon JB, Shepherd RK, Irvine DRF. Effects of chronic cochlear electrical stimulation after an extended period of profound deafness on primary auditory cortex organization in cats. Eur J Neurosci 2013; 39:811-20. [DOI: 10.1111/ejn.12445] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2013] [Revised: 11/06/2013] [Accepted: 11/07/2013] [Indexed: 11/29/2022]
Affiliation(s)
- James B. Fallon
- Bionics Institute; 384-388 Albert Street East Melbourne Vic. 3002 Australia
- Department of Otolaryngology; University of Melbourne; Melbourne Vic. Australia
- Medical Bionics Department; University of Melbourne; Melbourne Vic. Australia
| | - Robert K. Shepherd
- Bionics Institute; 384-388 Albert Street East Melbourne Vic. 3002 Australia
- Department of Otolaryngology; University of Melbourne; Melbourne Vic. Australia
- Medical Bionics Department; University of Melbourne; Melbourne Vic. Australia
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23
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Carrasco A, Lomber SG. Influence of inter-field communication on neuronal response synchrony across auditory cortex. Hear Res 2013; 304:57-69. [DOI: 10.1016/j.heares.2013.05.012] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/31/2013] [Revised: 05/21/2013] [Accepted: 05/27/2013] [Indexed: 11/25/2022]
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Carrasco A, Kok MA, Lomber SG. Effects of core auditory cortex deactivation on neuronal response to simple and complex acoustic signals in the contralateral anterior auditory field. Cereb Cortex 2013; 25:84-96. [PMID: 23960202 DOI: 10.1093/cercor/bht205] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Interhemispheric communication has been implicated in various functions of sensory signal processing and perception. Despite ample evidence demonstrating this phenomenon in the visual and somatosensory systems, to date, limited functional assessment of transcallosal transmission during periods of acoustic signal exposure has hindered our understanding of the role of interhemispheric connections between auditory cortical fields. Consequently, the present investigation examines the impact of core auditory cortical field deactivation on response properties of contralateral anterior auditory field (AAF) neurons in the felis catus. Single-unit responses to simple and complex acoustic signals were measured across AAF before, during, and after individual and combined cooling deactivation of contralateral primary auditory cortex (A1) and AAF neurons. Data analyses revealed that on average: 1) interhemispheric projections from core auditory areas to contralateral AAF neurons are predominantly excitatory, 2) changes in response strength vary based on acoustic features, 3) A1 and AAF projections can modulate AAF activity differently, 4) decreases in response strength are not specific to particular cortical laminae, and 5) contralateral inputs modulate AAF neuronal response thresholds. Collectively, these observations demonstrate that A1 and AAF neurons predominantly modulate AAF response properties via excitatory projections.
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Affiliation(s)
- Andres Carrasco
- Brain and Mind Institute, Department of Physiology and Pharmacology, Schulich School of Medicine and Dentistry, University of Western Ontario, London, ON, Canada N6A 5C1 Cerebral Systems Laboratory, Department of Psychology, University of Western Ontario, London, ON, Canada N6A 5C2
| | - Melanie A Kok
- Brain and Mind Institute, Department of Physiology and Pharmacology, Schulich School of Medicine and Dentistry, University of Western Ontario, London, ON, Canada N6A 5C1 Cerebral Systems Laboratory, Department of Psychology, University of Western Ontario, London, ON, Canada N6A 5C2
| | - Stephen G Lomber
- Brain and Mind Institute, Department of Physiology and Pharmacology, Schulich School of Medicine and Dentistry, University of Western Ontario, London, ON, Canada N6A 5C1 Cerebral Systems Laboratory, Department of Psychology, University of Western Ontario, London, ON, Canada N6A 5C2
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25
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De Martino F, Moerel M, van de Moortele PF, Ugurbil K, Goebel R, Yacoub E, Formisano E. Spatial organization of frequency preference and selectivity in the human inferior colliculus. Nat Commun 2013; 4:1386. [PMID: 23340426 PMCID: PMC3556928 DOI: 10.1038/ncomms2379] [Citation(s) in RCA: 83] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2012] [Accepted: 12/12/2012] [Indexed: 01/10/2023] Open
Abstract
To date, the functional organization of human auditory sub-cortical structures can only be inferred from animal models. Here we use high-resolution functional MRI at ultra-high magnetic fields (7 Tesla) to map the organization of spectral responses in the human inferior colliculus (hIC), a sub-cortical structure fundamental for sound processing. We reveal a tonotopic map with a spatial gradient of preferred frequencies approximately oriented from dorso-lateral (low frequencies) to ventro-medial (high frequencies) locations. Furthermore, we observe a spatial organization of spectral selectivity (tuning) of fMRI responses in the hIC. Along isofrequency contours, fMRI-tuning is narrowest in central locations and broadest in the surrounding regions. Finally, by comparing sub-cortical and cortical auditory areas we show that fMRI-tuning is narrower in hIC than on the cortical surface. Our findings pave the way to non-invasive investigations of sound processing in human sub-cortical nuclei and to studying the interplay between sub-cortical and cortical neuronal populations.
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Affiliation(s)
- Federico De Martino
- Faculty of Psychology and Neuroscience, Department of Cognitive Neurosciences, Maastricht University, Universiteitssingel 40, Maastricht 6229ER, The Netherlands.
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26
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Processing of natural sounds in human auditory cortex: tonotopy, spectral tuning, and relation to voice sensitivity. J Neurosci 2013; 32:14205-16. [PMID: 23055490 DOI: 10.1523/jneurosci.1388-12.2012] [Citation(s) in RCA: 126] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Auditory cortical processing of complex meaningful sounds entails the transformation of sensory (tonotopic) representations of incoming acoustic waveforms into higher-level sound representations (e.g., their category). However, the precise neural mechanisms enabling such transformations remain largely unknown. In the present study, we use functional magnetic resonance imaging (fMRI) and natural sounds stimulation to examine these two levels of sound representation (and their relation) in the human auditory cortex. In a first experiment, we derive cortical maps of frequency preference (tonotopy) and selectivity (tuning width) by mathematical modeling of fMRI responses to natural sounds. The tuning width maps highlight a region of narrow tuning that follows the main axis of Heschl's gyrus and is flanked by regions of broader tuning. The narrowly tuned portion on Heschl's gyrus contains two mirror-symmetric frequency gradients, presumably defining two distinct primary auditory areas. In addition, our analysis indicates that spectral preference and selectivity (and their topographical organization) extend well beyond the primary regions and also cover higher-order and category-selective auditory regions. In particular, regions with preferential responses to human voice and speech occupy the low-frequency portions of the tonotopic map. We confirm this observation in a second experiment, where we find that speech/voice selective regions exhibit a response bias toward the low frequencies characteristic of human voice and speech, even when responding to simple tones. We propose that this frequency bias reflects the selective amplification of relevant and category-characteristic spectral bands, a useful processing step for transforming a sensory (tonotopic) sound image into higher level neural representations.
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27
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Atencio CA, Schreiner CE. Spectrotemporal processing in spectral tuning modules of cat primary auditory cortex. PLoS One 2012; 7:e31537. [PMID: 22384036 PMCID: PMC3288040 DOI: 10.1371/journal.pone.0031537] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2011] [Accepted: 01/09/2012] [Indexed: 12/02/2022] Open
Abstract
Spectral integration properties show topographical order in cat primary auditory cortex (AI). Along the iso-frequency domain, regions with predominantly narrowly tuned (NT) neurons are segregated from regions with more broadly tuned (BT) neurons, forming distinct processing modules. Despite their prominent spatial segregation, spectrotemporal processing has not been compared for these regions. We identified these NT and BT regions with broad-band ripple stimuli and characterized processing differences between them using both spectrotemporal receptive fields (STRFs) and nonlinear stimulus/firing rate transformations. The durations of STRF excitatory and inhibitory subfields were shorter and the best temporal modulation frequencies were higher for BT neurons than for NT neurons. For NT neurons, the bandwidth of excitatory and inhibitory subfields was matched, whereas for BT neurons it was not. Phase locking and feature selectivity were higher for NT neurons. Properties of the nonlinearities showed only slight differences across the bandwidth modules. These results indicate fundamental differences in spectrotemporal preferences - and thus distinct physiological functions - for neurons in BT and NT spectral integration modules. However, some global processing aspects, such as spectrotemporal interactions and nonlinear input/output behavior, appear to be similar for both neuronal subgroups. The findings suggest that spectral integration modules in AI differ in what specific stimulus aspects are processed, but they are similar in the manner in which stimulus information is processed.
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Affiliation(s)
- Craig A Atencio
- Coleman Memorial Laboratory, Department of Otolaryngology-HNS, The UCSF Center for Integrative Neuroscience, University of California San Francisco, San Francisco, California, United States of America.
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Trujillo M, Measor K, Carrasco MM, Razak KA. Selectivity for the rate of frequency-modulated sweeps in the mouse auditory cortex. J Neurophysiol 2011; 106:2825-37. [DOI: 10.1152/jn.00480.2011] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Frequency-modulated (FM) sweeps are common components of vocalizations, including human speech. Both sweep direction and rate influence discrimination of vocalizations. Across species, relatively less is known about FM rate selectivity compared with direction selectivity. In this study, FM rate selectivity was studied in the auditory cortex of anesthetized 1- to 3-mo-old C57bl/6 mice. Neurons were classified as fast pass, band pass, slow pass, or all pass depending on their selectivity for rates between 0.08 and 20 kHz/ms. Multiunit recordings were used to map FM rate selectivity at depths between 250 and 450 μm across both primary auditory cortex (A1) and the anterior auditory field (AAF). In terms of functional organization of rate selectivity, three patterns were found. First, in both A1 and AAF, neurons clustered according to rate selectivity. Second, most (∼60%) AAF neurons were either fast-pass or band-pass selective. Most A1 neurons (∼72%) were slow-pass selective. This distribution supports the hypothesis that AAF is specialized for faster temporal processing than A1. Single-unit recordings ( n = 223) from A1 and AAF show that the mouse auditory cortex is best poised to detect and discriminate a narrow range of sweep rates between 0.5 and 3 kHz/ms. Third, based on recordings obtained at different depths, neurons in the infragranular layers were less rate selective than neurons in the granular layers, suggesting FM processing undergoes changes within the cortical column. On average, there was very little direction selectivity in the mouse auditory cortex. There was also no correlation between characteristic frequency and direction selectivity. The narrow range of rate selectivity in the mouse cortex indicates that FM rate processing is a useful physiological marker for studying contributions of genetic and environmental factors in auditory system development, aging, and disease.
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Affiliation(s)
| | | | | | - Khaleel A. Razak
- Department of Psychology, University of California, Riverside, California
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29
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Meredith MA, Lomber SG. Somatosensory and visual crossmodal plasticity in the anterior auditory field of early-deaf cats. Hear Res 2011; 280:38-47. [PMID: 21354286 PMCID: PMC3134631 DOI: 10.1016/j.heares.2011.02.004] [Citation(s) in RCA: 82] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/16/2010] [Revised: 02/08/2011] [Accepted: 02/10/2011] [Indexed: 01/28/2023]
Abstract
It is well known that the post-natal loss of sensory input in one modality can result in crossmodal reorganization of the deprived cortical areas, but deafness fails to induce crossmodal effects in cat primary auditory cortex (A1). Because the core auditory regions (A1, and anterior auditory field AAF) are arranged as separate, parallel processors, it cannot be assumed that early-deafness affects one in the same manner as the other. The present experiments were conducted to determine if crossmodal effects occur in the anterior auditory field (AAF). Using mature cats (n = 3), ototoxically deafened postnatally, single-unit recordings were made in the gyral and sulcal portions of the AAF. In contrast to the auditory responsivity found in the hearing controls, none of the neurons in early-deafened AAF were activated by auditory stimulation. Instead, the majority (78%) were activated by somatosensory cues, while fewer were driven by visual stimulation (44%; values include unisensory and bimodal neurons). Somatosensory responses could be activated from all locations on the body surface but most often occurred on the head, were often bilateral (e.g., occupied portions of both sides of the body), and were primarily excited by low-threshold hair receptors. Visual receptive fields were large, collectively represented the contralateral visual field, and exhibited conventional response properties such as movement direction and velocity preferences. These results indicate that, following post-natal deafness, both somatosensory and visual modalities participate in crossmodal reinnervation of the AAF, consistent with the growing literature that documents deafness-induced crossmodal plasticity outside A1.
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Affiliation(s)
- M Alex Meredith
- Department of Anatomy and Neurobiology, Virginia Commonwealth University, School of Medicine, Richmond VA 23298-0709, USA.
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30
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Carrasco A, Lomber SG. Neuronal activation times to simple, complex, and natural sounds in cat primary and nonprimary auditory cortex. J Neurophysiol 2011; 106:1166-78. [DOI: 10.1152/jn.00940.2010] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Interactions between living organisms and the environment are commonly regulated by accurate and timely processing of sensory signals. Hence, behavioral response engagement by an organism is typically constrained by the arrival time of sensory information to the brain. While psychophysical response latencies to acoustic information have been investigated, little is known about how variations in neuronal response time relate to sensory signal characteristics. Consequently, the primary objective of the present investigation was to determine the pattern of neuronal activation induced by simple (pure tones), complex (noise bursts and frequency modulated sweeps), and natural (conspecific vocalizations) acoustic signals of different durations in cat auditory cortex. Our analysis revealed three major cortical response characteristics. First, latency measures systematically increase in an antero-dorsal to postero-ventral direction among regions of auditory cortex. Second, complex acoustic stimuli reliably provoke faster neuronal response engagement than simple stimuli. Third, variations in neuronal response time induced by changes in stimulus duration are dependent on acoustic spectral features. Collectively, these results demonstrate that acoustic signals, regardless of complexity, induce a directional pattern of activation in auditory cortex.
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Affiliation(s)
- Andres Carrasco
- Centre for Brain and Mind, Department of Physiology and Pharmacology, Schulich School of Medicine and Dentistry and Cerebral Systems Laboratory, Department of Psychology, Faculty of Social Science, University of Western Ontario, London, Ontario, Canada
| | - Stephen G. Lomber
- Centre for Brain and Mind, Department of Physiology and Pharmacology, Schulich School of Medicine and Dentistry and Cerebral Systems Laboratory, Department of Psychology, Faculty of Social Science, University of Western Ontario, London, Ontario, Canada
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31
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Bizley J, King R. What Can Multisensory Processing Tell Us about the Functional Organization of Auditory Cortex? Front Neurosci 2011. [DOI: 10.1201/b11092-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
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32
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Bizley J, King R. What Can Multisensory Processing Tell Us about the Functional Organization of Auditory Cortex? Front Neurosci 2011. [DOI: 10.1201/9781439812174-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
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33
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Imaizumi K, Priebe NJ, Cheung SW, Schreiner CE. Spatial organization of repetition rate processing in cat anterior auditory field. Hear Res 2011; 280:70-81. [PMID: 21569829 DOI: 10.1016/j.heares.2011.04.008] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/23/2010] [Revised: 03/30/2011] [Accepted: 04/18/2011] [Indexed: 10/18/2022]
Abstract
Auditory cortex updates incoming information on a segment by segment basis for human speech and animal communication. Measuring repetition rate transfer functions (RRTFs) captures temporal responses to repetitive sounds. In this study, we used repetitive click trains to describe the spatial distribution of RRTF responses in cat anterior auditory field (AAF) and to discern potential variations in local temporal processing capacity. A majority of RRTF filters are band-pass. Temporal parameters estimated from RRTFs and corrected for characteristic frequency or latency dependencies are non-homogeneously distributed across AAF. Unlike the shallow global gradient observed in spectral receptive field parameters, transitions from loci with high to low temporal parameters are steep. Quantitative spatial analysis suggests non-uniform, circumscribed local organization for temporal pattern processing superimposed on global organization for spectral processing in cat AAF.
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Affiliation(s)
- Kazuo Imaizumi
- Coleman Memorial Laboratory, W.M. Keck Center for Integrative Neuroscience, University of California, San Francisco, CA 94143-0732, United States.
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34
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Watkins PV, Barbour DL. Rate-level responses in awake marmoset auditory cortex. Hear Res 2011; 275:30-42. [PMID: 21145961 PMCID: PMC3095711 DOI: 10.1016/j.heares.2010.11.011] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/29/2009] [Revised: 11/24/2010] [Accepted: 11/30/2010] [Indexed: 11/18/2022]
Abstract
Investigations of auditory neuronal firing rate as a function of sound level have revealed a wide variety of rate-level function shapes, including neurons with nonmonotonic or level-tuned functions. These neurons have an unclear role in auditory processing but have been found to be quite common. In the present study of awake marmoset primary auditory cortex (A1) neurons, 56% (305 out of 544), when stimulated with tones at the highest sound level tested, exhibited a decrement in driven rate of at least 50% from the maximum. These nonmonotonic neurons demonstrated significantly lower response thresholds than monotonic neurons, although both populations exhibited thresholds skewed toward lower values. Nonmonotonic neurons significantly outnumbered monotonic neurons in the frequency range 6-13 kHz, which is the frequency range containing most marmoset vocalization energy. Spontaneous rate was inversely correlated with threshold in both populations, and spontaneous rates of nonmonotonic neurons had significantly lower values than spontaneous rates of monotonic neurons, although distributions of maximum driven rates were not significantly different. Finally, monotonicity was found to be organized within electrode penetrations like characteristic frequency but with less structure. These findings are consistent with the hypothesis that nonmonotonic neurons play a unique role in representing sound level, particularly at the lowest sound levels and for complex vocalizations.
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Affiliation(s)
- Paul V Watkins
- Laboratory of Sensory Neuroscience and Neuroengineering, Department of Biomedical Engineering, Washington University, One Brookings Dr., Campus Box 1097, St. Louis, MO 63130, USA
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35
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Read HL, Nauen DW, Escabí MA, Miller LM, Schreiner CE, Winer JA. Distinct core thalamocortical pathways to central and dorsal primary auditory cortex. Hear Res 2011; 274:95-104. [PMID: 21145383 PMCID: PMC3275343 DOI: 10.1016/j.heares.2010.11.010] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/12/2010] [Revised: 11/26/2010] [Accepted: 11/30/2010] [Indexed: 11/20/2022]
Abstract
The cat primary auditory cortex (AI) is usually assumed to form one continuous functional region. However, the dorsal and central parts of the AI iso-frequency domain contain neurons that have distinct response properties to acoustic stimuli. In this study, we asked whether neurons projecting to dorsal versus central regions of AI originate in different parts of the medial geniculate body (MGB). Spike rate responses to variations in the sound level and frequency of pure tones were used to measure characteristic frequency (CF) and frequency resolution. These were mapped with high spatial density in order to place retrograde tracers into matching frequency regions of the central narrow-band region (cNB) and dorsal AI. Labeled neurons projecting to these two parts of AI were concentrated in the middle and rostral thirds of the MGB, respectively. There was little evidence that differences in dorsal and central AI function could be due to convergent input from cells outside the ventral division of the MGB (MGBv). Instead, inputs arising from different locations along the caudal-to-rostral dimension of MGBv represent potential sources of response differences between central and dorsal sub-regions of AI.
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Affiliation(s)
- Heather L Read
- WM Keck Center for Integrative Neuroscience, University of California at San Francisco, San Francisco, CA 94143, USA.
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36
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Storace DA, Higgins NC, Read HL. Thalamocortical pathway specialization for sound frequency resolution. J Comp Neurol 2010; 519:177-93. [DOI: 10.1002/cne.22501] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
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37
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Imaizumi K, Priebe NJ, Sharpee TO, Cheung SW, Schreiner CE. Encoding of temporal information by timing, rate, and place in cat auditory cortex. PLoS One 2010; 5:e11531. [PMID: 20657832 PMCID: PMC2906504 DOI: 10.1371/journal.pone.0011531] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2009] [Accepted: 06/08/2010] [Indexed: 11/19/2022] Open
Abstract
A central goal in auditory neuroscience is to understand the neural coding of species-specific communication and human speech sounds. Low-rate repetitive sounds are elemental features of communication sounds, and core auditory cortical regions have been implicated in processing these information-bearing elements. Repetitive sounds could be encoded by at least three neural response properties: 1) the event-locked spike-timing precision, 2) the mean firing rate, and 3) the interspike interval (ISI). To determine how well these response aspects capture information about the repetition rate stimulus, we measured local group responses of cortical neurons in cat anterior auditory field (AAF) to click trains and calculated their mutual information based on these different codes. ISIs of the multiunit responses carried substantially higher information about low repetition rates than either spike-timing precision or firing rate. Combining firing rate and ISI codes was synergistic and captured modestly more repetition information. Spatial distribution analyses showed distinct local clustering properties for each encoding scheme for repetition information indicative of a place code. Diversity in local processing emphasis and distribution of different repetition rate codes across AAF may give rise to concurrent feed-forward processing streams that contribute differently to higher-order sound analysis.
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Affiliation(s)
- Kazuo Imaizumi
- Coleman Memorial Laboratory, W. M. Keck Center for Integrative Neuroscience, Department of Otolaryngology-Head and Neck Surgery, University of California San Francisco, San Francisco, California, United States of America
- Neuroscience Center, Louisiana State University Health Sciences Center, New Orleans, Louisiana, United States of America
- * E-mail: (KI); (CES)
| | - Nicholas J. Priebe
- Section of Neurobiology, School of Biological Sciences, University of Texas at Austin, Austin, Texas, United States of America
| | - Tatyana O. Sharpee
- Sloan-Swartz Center for Theoretical Neurobiology, University of California San Francisco, San Francisco, California, United States of America
- Computational Neurobiology Laboratory, Salk Institute for Biological Studies, La Jolla, California, United States of America
| | - Steven W. Cheung
- Coleman Memorial Laboratory, W. M. Keck Center for Integrative Neuroscience, Department of Otolaryngology-Head and Neck Surgery, University of California San Francisco, San Francisco, California, United States of America
| | - Christoph E. Schreiner
- Coleman Memorial Laboratory, W. M. Keck Center for Integrative Neuroscience, Department of Otolaryngology-Head and Neck Surgery, University of California San Francisco, San Francisco, California, United States of America
- Sloan-Swartz Center for Theoretical Neurobiology, University of California San Francisco, San Francisco, California, United States of America
- * E-mail: (KI); (CES)
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38
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Reciprocal modulatory influences between tonotopic and nontonotopic cortical fields in the cat. J Neurosci 2010; 30:1476-87. [PMID: 20107075 DOI: 10.1523/jneurosci.5708-09.2009] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Functional and anatomical studies suggest that acoustic signals are processed hierarchically in auditory cortex. Although most regions of acoustically responsive cortex are not tonotopically organized, all previous electrophysiological investigations of interfield interactions have only examined tonotopically represented areas. The purpose of the present study was to investigate the functional interactions between tonotopically and nontonotopically organized fields in auditory cortex. We accomplished this goal by examining the bidirectional contributions between the cochleotopically organized primary auditory cortex (A1) and the noncochleotopically organized second auditory field (A2). Multiunit acute recording procedures in combination with reversible cooling deactivation techniques were used in eight mature cats. The synaptic activity of A1 or A2 was suppressed while the neuronal response to tonal stimuli of the noninactivated area (A1 or A2) was measured. Response strength, neuronal threshold, receptive field bandwidths, and latency measures were collected at each recorded site before, during, and after cooling deactivation epochs. Our analysis revealed comparable changes in A1 and A2 neuronal response properties. Specifically, significant decreases in neuronal response strength, increases in neuronal threshold, and shortening of response latency were found in both fields during periods of cooling deactivation. The weak anatomical connections between the two fields investigated make these findings unexpected. Furthermore, the observed neuronal changes suggest a model of corticocortical interaction among auditory fields in which neither differences in the magnitude of anatomical projections nor cortical representation of sensory stimuli are reliable determinants of modulatory functions.
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39
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Rajan R, Irvine DRF. Severe and extensive neonatal hearing loss in cats results in auditory cortex plasticity that differentiates into two regions. Eur J Neurosci 2010; 31:1999-2013. [PMID: 20497473 DOI: 10.1111/j.1460-9568.2010.07214.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
We examined the response characteristics of primary auditory cortex (A1) neurons in adult cats partially but extensively deafened by ototoxic drugs 2-8 days after birth. The damage evoked extensive A1 topographic map reorganization as also found by others, but a novel finding was that in the majority of cats with low-frequency edges to the cochlear lesion, the area of reorganization segregated into two areas expressing the same novel frequency inputs but differentiated by neuronal sensitivity and responsiveness. Immediately adjacent to normal A1 is an approximately 1.2-mm-wide area of reorganization in which sensitivity and responsiveness to sound are similar to that in normal A1 in the same animals and in unlesioned adult animals. Extending further into deprived A1 is a more extensive area of reorganization where neurons have poorer sensitivity and responsiveness to new inputs. These two areas did not differ in response-area bandwidth and response latency. We interpret these novel changes as the cortical consequences of severe receptor organ lesions extending to low-frequency cochlear regions. We speculate that the two areas of A1 reorganization may reflect differences in the transcortical spatial distribution of thalamo-cortical and horizontal intracortical connections. Qualitatively similar changes in response properties have been seen after retinal lesions producing large areas of visual cortical reorganization, suggesting they might be a general consequence of receptor lesions that deprive large regions of cortex of normal input. These effects may have perceptual implications for the use of cochlear implants in patients with residual low-frequency hearing.
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Affiliation(s)
- R Rajan
- Department of Physiology, Monash University, Vic. 3800, Australia.
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40
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Mellott JG, Van der Gucht E, Lee CC, Carrasco A, Winer JA, Lomber SG. Areas of cat auditory cortex as defined by neurofilament proteins expressing SMI-32. Hear Res 2010; 267:119-36. [PMID: 20430082 DOI: 10.1016/j.heares.2010.04.003] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/12/2009] [Revised: 02/22/2010] [Accepted: 04/05/2010] [Indexed: 10/19/2022]
Abstract
The monoclonal antibody SMI-32 was used to characterize and distinguish individual areas of cat auditory cortex. SMI-32 labels non-phosphorylated epitopes on the high- and medium-molecular weight subunits of neurofilament proteins in cortical pyramidal cells and dendritic trees with the most robust immunoreactivity in layers III and V. Auditory areas with unique patterns of immunoreactivity included: primary auditory cortex (AI), second auditory cortex (AII), dorsal zone (DZ), posterior auditory field (PAF), ventral posterior auditory field (VPAF), ventral auditory field (VAF), temporal cortex (T), insular cortex (IN), anterior auditory field (AAF), and the auditory field of the anterior ectosylvian sulcus (fAES). Unique patterns of labeling intensity, soma shape, soma size, layers of immunoreactivity, laminar distribution of dendritic arbors, and labeled cell density were identified. Features that were consistent in all areas included: layers I and IV neurons are immunonegative; nearly all immunoreactive cells are pyramidal; and immunoreactive neurons are always present in layer V. To quantify the results, the numbers of labeled cells and dendrites, as well as cell diameter, were collected and used as tools for identifying and differentiating areas. Quantification of the labeling patterns also established profiles for ten auditory areas/layers and their degree of immunoreactivity. Areal borders delineated by SMI-32 were highly correlated with tonotopically-defined areal boundaries. Overall, SMI-32 immunoreactivity can delineate ten areas of cat auditory cortex and demarcate topographic borders. The ability to distinguish auditory areas with SMI-32 is valuable for the identification of auditory cerebral areas in electrophysiological, anatomical, and/or behavioral investigations.
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Affiliation(s)
- Jeffrey G Mellott
- Centre for Brain and Mind, Department of Physiology & Pharmacology, Schulich School of Medicine and Dentistry, The University of Western Ontario, Medical Sciences Building, Room 216, 1151 Richmond Street North, London, Ontario N6A 5C1, Canada
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41
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Hackett TA. Information flow in the auditory cortical network. Hear Res 2010; 271:133-46. [PMID: 20116421 DOI: 10.1016/j.heares.2010.01.011] [Citation(s) in RCA: 198] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/08/2009] [Revised: 01/15/2010] [Accepted: 01/22/2010] [Indexed: 11/16/2022]
Abstract
Auditory processing in the cerebral cortex is comprised of an interconnected network of auditory and auditory-related areas distributed throughout the forebrain. The nexus of auditory activity is located in temporal cortex among several specialized areas, or fields, that receive dense inputs from the medial geniculate complex. These areas are collectively referred to as auditory cortex. Auditory activity is extended beyond auditory cortex via connections with auditory-related areas elsewhere in the cortex. Within this network, information flows between areas to and from countless targets, but in a manner that is characterized by orderly regional, areal and laminar patterns. These patterns reflect some of the structural constraints that passively govern the flow of information at all levels of the network. In addition, the exchange of information within these circuits is dynamically regulated by intrinsic neurochemical properties of projecting neurons and their targets. This article begins with an overview of the principal circuits and how each is related to information flow along major axes of the network. The discussion then turns to a description of neurochemical gradients along these axes, highlighting recent work on glutamate transporters in the thalamocortical projections to auditory cortex. The article concludes with a brief discussion of relevant neurophysiological findings as they relate to structural gradients in the network.
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Affiliation(s)
- Troy A Hackett
- Dept. of Hearing and Speech Sciences, Vanderbilt University School of Medicine, 301 Wilson Hall, 111 21st Avenue South Nashville, TN 37203, USA.
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42
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Evidence for hierarchical processing in cat auditory cortex: nonreciprocal influence of primary auditory cortex on the posterior auditory field. J Neurosci 2009; 29:14323-33. [PMID: 19906979 DOI: 10.1523/jneurosci.2905-09.2009] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The auditory cortex of the cat is composed of 13 distinct fields that have been defined on the basis of anatomy, physiology, and behavior. Although an anatomically based hierarchical processing scheme has been proposed in auditory cortex, few functional studies have examined how these areas influence one another. The purpose of the present study was to examine the bidirectional processing contributions between primary auditory cortex (A1) and the nonprimary posterior auditory field (PAF). Multiunit acute recording techniques in eight mature cats were used to measure neuronal responses to tonal stimuli in A1 or PAF while synaptic activity from PAF or A1 was suppressed with reversible cooling deactivation techniques. Specifically, in four animals, electrophysiological recordings in A1 were conducted before, during, and after deactivation of PAF. Similarly, in the other four animals, PAF activity was measured before, during, and after deactivation of A1. The characteristic frequency, bandwidth, and neuronal threshold were calculated at each receptive field collected and the response strength and response latency measures were calculated from cumulative peristimulus time histograms. Two major changes in PAF response properties were observed during A1 deactivation: a decrease in response strength and a reduction in receptive field bandwidths. In comparison, we did not identify any significant changes in A1 neuronal responses during deactivation of PAF neurons. These findings support proposed models of hierarchal processing in cat auditory cortex.
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43
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Pienkowski M, Eggermont JJ. Long-term, partially-reversible reorganization of frequency tuning in mature cat primary auditory cortex can be induced by passive exposure to moderate-level sounds. Hear Res 2009; 257:24-40. [DOI: 10.1016/j.heares.2009.07.011] [Citation(s) in RCA: 98] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/19/2009] [Revised: 07/10/2009] [Accepted: 07/27/2009] [Indexed: 11/26/2022]
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44
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Differential modulatory influences between primary auditory cortex and the anterior auditory field. J Neurosci 2009; 29:8350-62. [PMID: 19571126 DOI: 10.1523/jneurosci.6001-08.2009] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Neuroanatomical studies have revealed a vast network of corticocortical connections among the various fields that form cat auditory cortex. However, few studies have explored the functional communicative properties of these connections. The purpose of the present study was to examine the bidirectional processing contributions between the primary auditory cortex (A1) and the nonprimary anterior auditory field (AAF). Using acute recording techniques, multiunit neuronal activity was collected from the right hemisphere of nine mature cats. Cortical maps were generated, and the precise location of A1 and AAF was identified. Subsequently, the synaptic activity of A1 or AAF was suppressed with reversible thermal deactivation procedures while the neuronal response to tonal stimuli of the non-inactivated area (A1 or AAF) was measured. We examined response strength and latency, characteristic frequency, bandwidth, and neuronal threshold of A1 and AAF receptive fields before and during epochs of deactivation. Three major changes in A1 response properties were observed during AAF neuronal suppression: a decrease in response strength, an increase in neuronal thresholds, and a sharpening of receptive field bandwidths. In contrast, A1 deactivation did not produce any discernible changes in AAF neuronal responses. Collectively, these results suggest that the modulation of acoustic information between A1 and AAF in cat auditory cortex is dominated by a unidirectional AAF to A1 pathway.
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45
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Polley DB, Hillock AR, Spankovich C, Popescu MV, Royal DW, Wallace MT. Development and plasticity of intra- and intersensory information processing. J Am Acad Audiol 2009; 19:780-98. [PMID: 19358458 DOI: 10.3766/jaaa.19.10.6] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The functional architecture of sensory brain regions reflects an ingenious biological solution to the competing demands of a continually changing sensory environment. While they are malleable, they have the constancy necessary to support a stable sensory percept. How does the functional organization of sensory brain regions contend with these antithetical demands? Here we describe the functional organization of auditory and multisensory (i.e., auditory-visual) information processing in three sensory brain structures: (1) a low-level unisensory cortical region, the primary auditory cortex (A1); (2) a higher-order multisensory cortical region, the anterior ectosylvian sulcus (AES); and (3) a multisensory subcortical structure, the superior colliculus (SC). We then present a body of work that characterizes the ontogenic expression of experience-dependent influences on the operations performed by the functional circuits contained within these regions. We will present data to support the hypothesis that the competing demands for plasticity and stability are addressed through a developmental transition in operational properties of functional circuits from an initially labile mode in the early stages of postnatal development to a more stable mode in the mature brain that retains the capacity for plasticity under specific experiential conditions. Finally, we discuss parallels between the central tenets of functional organization and plasticity of sensory brain structures drawn from animal studies and a growing literature on human brain plasticity and the potential applicability of these principles to the audiology clinic.
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Affiliation(s)
- Daniel B Polley
- Vanderbilt Bill Wilkerson Center for Otolaryngology and Communication Sciences, Department of Hearing and Speech Sciences, Vanderbilt Kennedy Center for Human Development, Vanderbilt University Medical School, USA.
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46
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Bizley JK, Walker KMM, Silverman BW, King AJ, Schnupp JWH. Interdependent encoding of pitch, timbre, and spatial location in auditory cortex. J Neurosci 2009; 29:2064-75. [PMID: 19228960 PMCID: PMC2663390 DOI: 10.1523/jneurosci.4755-08.2009] [Citation(s) in RCA: 108] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2008] [Revised: 01/09/2008] [Accepted: 01/13/2009] [Indexed: 11/21/2022] Open
Abstract
Because we can perceive the pitch, timbre, and spatial location of a sound source independently, it seems natural to suppose that cortical processing of sounds might separate out spatial from nonspatial attributes. Indeed, recent studies support the existence of anatomically segregated "what" and "where" cortical processing streams. However, few attempts have been made to measure the responses of individual neurons in different cortical fields to sounds that vary simultaneously across spatial and nonspatial dimensions. We recorded responses to artificial vowels presented in virtual acoustic space to investigate the representations of pitch, timbre, and sound source azimuth in both core and belt areas of ferret auditory cortex. A variance decomposition technique was used to quantify the way in which altering each parameter changed neural responses. Most units were sensitive to two or more of these stimulus attributes. Although indicating that neural encoding of pitch, location, and timbre cues is distributed across auditory cortex, significant differences in average neuronal sensitivity were observed across cortical areas and depths, which could form the basis for the segregation of spatial and nonspatial cues at higher cortical levels. Some units exhibited significant nonlinear interactions between particular combinations of pitch, timbre, and azimuth. These interactions were most pronounced for pitch and timbre and were less commonly observed between spatial and nonspatial attributes. Such nonlinearities were most prevalent in primary auditory cortex, although they tended to be small compared with stimulus main effects.
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Affiliation(s)
- Jennifer K Bizley
- Department of Physiology, Anatomy, and Genetics, University of Oxford, Oxford OX1 3PT, United Kingdom.
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Bizley JK, King AJ. Visual-auditory spatial processing in auditory cortical neurons. Brain Res 2008; 1242:24-36. [PMID: 18407249 PMCID: PMC4340571 DOI: 10.1016/j.brainres.2008.02.087] [Citation(s) in RCA: 102] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2007] [Revised: 02/18/2008] [Accepted: 02/21/2008] [Indexed: 11/27/2022]
Abstract
Neurons responsive to visual stimulation have now been described in the auditory cortex of various species, but their functions are largely unknown. Here we investigate the auditory and visual spatial sensitivity of neurons recorded in 5 different primary and non-primary auditory cortical areas of the ferret. We quantified the spatial tuning of neurons by measuring the responses to stimuli presented across a range of azimuthal positions and calculating the mutual information (MI) between the neural responses and the location of the stimuli that elicited them. MI estimates of spatial tuning were calculated for unisensory visual, unisensory auditory and for spatially and temporally coincident auditory-visual stimulation. The majority of visually responsive units conveyed significant information about light-source location, whereas, over a corresponding region of space, acoustically responsive units generally transmitted less information about sound-source location. Spatial sensitivity for visual, auditory and bisensory stimulation was highest in the anterior dorsal field, the auditory area previously shown to be innervated by a region of extrastriate visual cortex thought to be concerned primarily with spatial processing, whereas the posterior pseudosylvian field and posterior suprasylvian field, whose principal visual input arises from cortical areas that appear to be part of the 'what' processing stream, conveyed less information about stimulus location. In some neurons, pairing visual and auditory stimuli led to an increase in the spatial information available relative to the most effective unisensory stimulus, whereas, in a smaller subpopulation, combined stimulation decreased the spatial MI. These data suggest that visual inputs to auditory cortex can enhance spatial processing in the presence of multisensory cues and could therefore potentially underlie visual influences on auditory localization.
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Affiliation(s)
- Jennifer K Bizley
- Department of Physiology, Anatomy and Genetics, University of Oxford, Parks Road, Oxford, OX1 3PT, UK.
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Bendor D, Wang X. Neural response properties of primary, rostral, and rostrotemporal core fields in the auditory cortex of marmoset monkeys. J Neurophysiol 2008; 100:888-906. [PMID: 18525020 DOI: 10.1152/jn.00884.2007] [Citation(s) in RCA: 162] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The core region of primate auditory cortex contains a primary and two primary-like fields (AI, primary auditory cortex; R, rostral field; RT, rostrotemporal field). Although it is reasonable to assume that multiple core fields provide an advantage for auditory processing over a single primary field, the differential roles these fields play and whether they form a functional pathway collectively such as for the processing of spectral or temporal information are unknown. In this report we compare the response properties of neurons in the three core fields to pure tones and sinusoidally amplitude modulated tones in awake marmoset monkeys (Callithrix jacchus). The main observations are as follows. (1) All three fields are responsive to spectrally narrowband sounds and are tonotopically organized. (2) Field AI responds more strongly to pure tones than fields R and RT. (3) Field RT neurons have lower best sound levels than those of neurons in fields AI and R. In addition, rate-level functions in field RT are more commonly nonmonotonic than in fields AI and R. (4) Neurons in fields RT and R have longer minimum latencies than those of field AI neurons. (5) Fields RT and R have poorer stimulus synchronization than that of field AI to amplitude-modulated tones. (6) Between the three core fields the more rostral regions (R and RT) have narrower firing-rate-based modulation transfer functions than that of AI. This effect was seen only for the nonsynchronized neurons. Synchronized neurons showed no such trend.
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Affiliation(s)
- Daniel Bendor
- Laboratory of Auditory Neurophysiology, Department of Biomedical Engineering, The Johns Hopkins University, 720 Rutland Avenue, Traylor 410, Baltimore, MD 21205, USA
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Harrington IA, Stecker GC, Macpherson EA, Middlebrooks JC. Spatial sensitivity of neurons in the anterior, posterior, and primary fields of cat auditory cortex. Hear Res 2008; 240:22-41. [PMID: 18359176 PMCID: PMC2515616 DOI: 10.1016/j.heares.2008.02.004] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/11/2007] [Revised: 02/11/2008] [Accepted: 02/12/2008] [Indexed: 10/22/2022]
Abstract
We assessed the spatial-tuning properties of units in the cat's anterior auditory field (AAF) and compared them with those observed previously in the primary (A1) and posterior auditory fields (PAF). Multi-channel, silicon-substrate probes were used to record single- and multi-unit activity from the right hemispheres of alpha-chloralose-anesthetized cats. Spatial tuning was assessed using broadband noise bursts that varied in azimuth or elevation. Response latencies were slightly, though significantly, shorter in AAF than A1, and considerably shorter in both of those fields than in PAF. Compared to PAF, spike counts and latencies were more poorly modulated by changes in stimulus location in AAF and A1, particularly at higher sound pressure levels. Moreover, units in AAF and A1 demonstrated poorer level tolerance than units in PAF with spike rates modulated as much by changes in stimulus intensity as changes in stimulus location. Finally, spike-pattern-recognition analyses indicated that units in AAF transmitted less spatial information, on average, than did units in PAF-an observation consistent with recent evidence that PAF is necessary for sound-localization behavior, whereas AAF is not.
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Affiliation(s)
- Ian A. Harrington
- Central Systems Laboratory, Kresge Hearing Research Institute, University of Michigan, Ann Arbor, MI
- Department of Psychology, Augustana College, Rock Island, IL
| | - G. Christopher Stecker
- Central Systems Laboratory, Kresge Hearing Research Institute, University of Michigan, Ann Arbor, MI
- Department of Speech and Hearing Sciences, University of Washington, Seattle, WA
| | - Ewan A. Macpherson
- Central Systems Laboratory, Kresge Hearing Research Institute, University of Michigan, Ann Arbor, MI
| | - John C. Middlebrooks
- Central Systems Laboratory, Kresge Hearing Research Institute, University of Michigan, Ann Arbor, MI
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Abstract
The mammalian auditory cortex (AC) is essential for computing the source and decoding the information contained in sound. Knowledge of AC corticocortical connections is modest other than in the primary auditory regions, nor is there an anatomical framework in the cat for understanding the patterns of connections among the many auditory areas. To address this issue we investigated cat AC connectivity in 13 auditory regions. Retrograde tracers were injected in the same area or in different areas to reveal the areal and laminar sources of convergent input to each region. Architectonic borders were established in Nissl and SMI-32 immunostained material. We assessed the topography, convergence, and divergence of the labeling. Intrinsic input constituted >50% of the projection cells in each area, and extrinsic inputs were strongest from functionally related areas. Each area received significant convergent ipsilateral input from several fields (5 to 8; mean 6). These varied in their laminar origin and projection density. Major extrinsic projections were preferentially from areas of the same functional type (tonotopic to tonotopic, nontonotopic to nontonotopic, limbic-related to limbic-related, multisensory-to-multisensory), while smaller projections link areas belonging to different groups. Branched projections between areas were <2% with deposits of two tracers in an area or in different areas. All extrinsic projections to each area were highly and equally topographic and clustered. Intrinsic input arose from all layers except layer I, and extrinsic input had unique, area-specific infragranular and supragranular origins. The many areal and laminar sources of input may contribute to the complexity of physiological responses in AC and suggest that many projections of modest size converge within each area rather than a simpler area-to-area serial or hierarchical pattern of corticocortical connectivity.
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Affiliation(s)
- Charles C Lee
- Division of Neurobiology, Department of Molecular and Cell Biology, University of California at Berkeley, Berkeley, California 94720-3200, USA.
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