151
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Straka MM, Schmitz S, Lim HH. Response features across the auditory midbrain reveal an organization consistent with a dual lemniscal pathway. J Neurophysiol 2014; 112:981-98. [PMID: 25128560 DOI: 10.1152/jn.00008.2014] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The central auditory system has traditionally been divided into lemniscal and nonlemniscal pathways leading from the midbrain through the thalamus to the cortex. This view has served as an organizing principle for studying, modeling, and understanding the encoding of sound within the brain. However, there is evidence that the lemniscal pathway could be further divided into at least two subpathways, each potentially coding for sound in different ways. We investigated whether such an interpretation is supported by the spatial distribution of response features in the central nucleus of the inferior colliculus (ICC), the part of the auditory midbrain assigned to the lemniscal pathway. We recorded responses to pure tone stimuli in the ICC of ketamine-xylazine-anesthetized guinea pigs and used three-dimensional brain reconstruction techniques to map the location of the recording sites. Compared with neurons in caudal-and-medial regions within an isofrequency lamina of the ICC, neurons in rostral-and-lateral regions responded with shorter first-spike latencies with less spiking jitter, shorter durations of spiking responses, a higher proportion of spikes occurring near the onset of the stimulus, lower thresholds, and larger local field potentials with shorter latencies. Further analysis revealed two distinct clusters of response features located in either the caudal-and-medial or the rostral-and-lateral parts of the isofrequency laminae of the ICC. Thus we report substantial differences in coding properties in two regions of the ICC that are consistent with the hypothesis that the lemniscal pathway is made up of at least two distinct subpathways from the midbrain up to the cortex.
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Affiliation(s)
- Małgorzata M Straka
- Department of Biomedical Engineering, University of Minnesota, Twin Cities, Minneapolis, Minnesota;
| | - Samuel Schmitz
- Department of Biomedical Engineering, University of Minnesota, Twin Cities, Minneapolis, Minnesota
| | - Hubert H Lim
- Department of Biomedical Engineering, University of Minnesota, Twin Cities, Minneapolis, Minnesota; Institute for Translational Neuroscience, University of Minnesota, Twin Cities, Minneapolis, Minnesota; and Department of Otolaryngology, University of Minnesota, Twin Cities, Minneapolis, Minnesota
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152
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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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153
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Degraded speech sound processing in a rat model of fragile X syndrome. Brain Res 2014; 1564:72-84. [PMID: 24713347 DOI: 10.1016/j.brainres.2014.03.049] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2014] [Revised: 03/29/2014] [Accepted: 03/31/2014] [Indexed: 12/29/2022]
Abstract
Fragile X syndrome is the most common inherited form of intellectual disability and the leading genetic cause of autism. Impaired phonological processing in fragile X syndrome interferes with the development of language skills. Although auditory cortex responses are known to be abnormal in fragile X syndrome, it is not clear how these differences impact speech sound processing. This study provides the first evidence that the cortical representation of speech sounds is impaired in Fmr1 knockout rats, despite normal speech discrimination behavior. Evoked potentials and spiking activity in response to speech sounds, noise burst trains, and tones were significantly degraded in primary auditory cortex, anterior auditory field and the ventral auditory field. Neurometric analysis of speech evoked activity using a pattern classifier confirmed that activity in these fields contains significantly less information about speech sound identity in Fmr1 knockout rats compared to control rats. Responses were normal in the posterior auditory field, which is associated with sound localization. The greatest impairment was observed in the ventral auditory field, which is related to emotional regulation. Dysfunction in the ventral auditory field may contribute to poor emotional regulation in fragile X syndrome and may help explain the observation that later auditory evoked responses are more disturbed in fragile X syndrome compared to earlier responses. Rodent models of fragile X syndrome are likely to prove useful for understanding the biological basis of fragile X syndrome and for testing candidate therapies.
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154
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Engineer CT, Centanni TM, Im KW, Borland MS, Moreno NA, Carraway RS, Wilson LG, Kilgard MP. Degraded auditory processing in a rat model of autism limits the speech representation in non-primary auditory cortex. Dev Neurobiol 2014; 74:972-86. [PMID: 24639033 DOI: 10.1002/dneu.22175] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2013] [Revised: 02/17/2014] [Accepted: 03/07/2014] [Indexed: 01/22/2023]
Abstract
Although individuals with autism are known to have significant communication problems, the cellular mechanisms responsible for impaired communication are poorly understood. Valproic acid (VPA) is an anticonvulsant that is a known risk factor for autism in prenatally exposed children. Prenatal VPA exposure in rats causes numerous neural and behavioral abnormalities that mimic autism. We predicted that VPA exposure may lead to auditory processing impairments which may contribute to the deficits in communication observed in individuals with autism. In this study, we document auditory cortex responses in rats prenatally exposed to VPA. We recorded local field potentials and multiunit responses to speech sounds in primary auditory cortex, anterior auditory field, ventral auditory field. and posterior auditory field in VPA exposed and control rats. Prenatal VPA exposure severely degrades the precise spatiotemporal patterns evoked by speech sounds in secondary, but not primary auditory cortex. This result parallels findings in humans and suggests that secondary auditory fields may be more sensitive to environmental disturbances and may provide insight into possible mechanisms related to auditory deficits in individuals with autism.
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Affiliation(s)
- C T Engineer
- School of Behavioral and Brain Sciences, The University of Texas at Dallas, Richardson, Texas, 75080
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155
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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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156
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Yokota R, Aihara K, Kanzaki R, Takahashi H. Learning-stage-dependent plasticity of temporal coherence in the auditory cortex of rats. Brain Topogr 2014; 28:401-10. [PMID: 24615394 DOI: 10.1007/s10548-014-0359-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2013] [Accepted: 02/20/2014] [Indexed: 10/25/2022]
Abstract
Temporal coherence among neural populations may contribute importantly to signal encoding, specifically by providing an optimal tradeoff between encoding reliability and efficiency. Here, we considered the possibility that learning modulates the temporal coherence among neural populations in association with well-characterized map plasticity. We previously demonstrated that, in appetitive operant conditioning tasks, the tone-responsive area globally expanded during the early stage of learning, but shrank during the late stage. The present study further showed that phase locking of the first spike to band-specific oscillations of local field potentials (LFPs) significantly increased during the early stage of learning but decreased during the late stage, suggesting that neurons in A1 were more synchronously activated during early learning, whereas they were more asynchronously activated once learning was completed. Furthermore, LFP amplitudes increased during early learning but decreased during later learning. These results suggest that, compared to naïve encoding, early-stage encoding is more reliable but energy-consumptive, whereas late-stage encoding is more energetically efficient. Such a learning-stage-dependent encoding strategy may underlie learning-induced, non-monotonic map plasticity. Accumulating evidence indicates that the cholinergic system is likely to be a shared neural substrate of the processes for perceptual learning and attention, both of which modulate neural encoding in an adaptive manner. Thus, a better understanding of the links between map plasticity and modulation of temporal coherence will likely lead to a more integrated view of learning and attention.
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Affiliation(s)
- Ryo Yokota
- Research Center for Advanced Science and Technology, The University of Tokyo, Komaba 4-6-1, Meguro-ku, Tokyo, 153-8904, Japan
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157
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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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158
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Antunes FM, Malmierca MS. An Overview of Stimulus-Specific Adaptation in the Auditory Thalamus. Brain Topogr 2013; 27:480-99. [DOI: 10.1007/s10548-013-0342-6] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2013] [Accepted: 12/05/2013] [Indexed: 12/30/2022]
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159
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Schreiner CE, Polley DB. Auditory map plasticity: diversity in causes and consequences. Curr Opin Neurobiol 2013; 24:143-56. [PMID: 24492090 DOI: 10.1016/j.conb.2013.11.009] [Citation(s) in RCA: 74] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2013] [Revised: 11/15/2013] [Accepted: 11/19/2013] [Indexed: 01/11/2023]
Abstract
Auditory cortical maps have been a long-standing focus of studies that assess the expression, mechanisms, and consequences of sensory plasticity. Here we discuss recent progress in understanding how auditory experience transforms spatially organized sound representations at higher levels of the central auditory pathways. New insights into the mechanisms underlying map changes have been achieved and more refined interpretations of various map plasticity effects and their consequences in terms of behavioral corollaries and learning as well as other cognitive aspects have been offered. The systematic organizational principles of cortical sound processing remain a key aspect in studying and interpreting the role of plasticity in hearing.
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Affiliation(s)
- Christoph E Schreiner
- Coleman Memorial Laboratory, UCSF Center for Integrative Neuroscience, University of California at San Francisco, San Francisco, CA 94143, USA.
| | - Daniel B Polley
- Eaton-Peabody Laboratory, Massachusetts Eye and Ear Infirmary, Department of Otology and Laryngology, Harvard Medical School, Boston, MA 02114, USA
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160
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Kyweriga M, Stewart W, Wehr M. Neuronal interaural level difference response shifts are level-dependent in the rat auditory cortex. J Neurophysiol 2013; 111:930-8. [PMID: 24335208 DOI: 10.1152/jn.00648.2013] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
How does the brain accomplish sound localization with invariance to total sound level? Sensitivity to interaural level differences (ILDs) is first computed at the lateral superior olive (LSO) and is observed at multiple levels of the auditory pathway, including the central nucleus of inferior colliculus (ICC) and auditory cortex. In LSO, this ILD sensitivity is level-dependent, such that ILD response functions shift toward the ipsilateral (excitatory) ear with increasing sound level. Thus early in the processing pathway changes in firing rate could indicate changes in sound location, sound level, or both. In ICC, while ILD responses can shift toward either ear in individual neurons, there is no net ILD response shift at the population level. In behavioral studies of human sound localization acuity, ILD sensitivity is invariant to increasing sound levels. Level-invariant sound localization would suggest transformation in level sensitivity between LSO and perception of sound sources. Whether this transformation is completed at the level of the ICC or continued at higher levels remains unclear. It also remains unknown whether perceptual sound localization is level-invariant in rats, as it is in humans. We asked whether ILD sensitivity is level-invariant in rat auditory cortex. We performed single-unit and whole cell recordings in rat auditory cortex under ketamine anesthesia and measured responses to white noise bursts presented through sealed earphones at a range of ILDs. Surprisingly, we found that with increasing sound levels ILD responses shifted toward the ipsilateral ear (which is typically inhibitory), regardless of whether cells preferred ipsilateral, contralateral, or binaural stimuli. Voltage-clamp recordings suggest that synaptic inhibition does not contribute substantially to this transformation in level sensitivity. We conclude that the level invariance of ILD sensitivity seen in behavioral studies is not present in rat auditory cortex.
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161
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Mylius J, Brosch M, Scheich H, Budinger E. Subcortical auditory structures in the Mongolian gerbil: I. Golgi architecture. J Comp Neurol 2013; 521:1289-321. [PMID: 23047461 DOI: 10.1002/cne.23232] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2012] [Revised: 08/25/2012] [Accepted: 10/02/2012] [Indexed: 12/17/2022]
Abstract
By means of the Golgi-Cox and Nissl methods we investigated the cyto- and fiberarchitecture as well as the morphology of neurons in the subcortical auditory structures of the Mongolian gerbil (Meriones unguiculatus), a frequently used animal model in auditory neuroscience. We describe the divisions and subdivisions of the auditory thalamus including the medial geniculate body, suprageniculate nucleus, and reticular thalamic nucleus, as well as of the inferior colliculi, nuclei of the lateral lemniscus, superior olivary complex, and cochlear nuclear complex. In this study, we 1) confirm previous results about the organization of the gerbil's subcortical auditory pathway using other anatomical staining methods (e.g., Budinger et al. [2000] Eur J Neurosci 12:2452-2474); 2) add substantially to the knowledge about the laminar and cellular organization of the gerbil's subcortical auditory structures, in particular about the orientation of their fibrodendritic laminae and about the morphology of their most distinctive neuron types; and 3) demonstrate that the cellular organization of these structures, as seen by the Golgi technique, corresponds generally to that of other mammalian species, in particular to that of rodents.
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Affiliation(s)
- Judith Mylius
- Special Laboratory Primate Neurobiology, Leibniz Institute for Neurobiology, D-39118 Magdeburg, Germany
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162
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Rode T, Hartmann T, Hubka P, Scheper V, Lenarz M, Lenarz T, Kral A, Lim HH. Neural representation in the auditory midbrain of the envelope of vocalizations based on a peripheral ear model. Front Neural Circuits 2013; 7:166. [PMID: 24155694 PMCID: PMC3800787 DOI: 10.3389/fncir.2013.00166] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2013] [Accepted: 09/24/2013] [Indexed: 11/24/2022] Open
Abstract
The auditory midbrain implant (AMI) consists of a single shank array (20 sites) for stimulation along the tonotopic axis of the central nucleus of the inferior colliculus (ICC) and has been safely implanted in deaf patients who cannot benefit from a cochlear implant (CI). The AMI improves lip-reading abilities and environmental awareness in the implanted patients. However, the AMI cannot achieve the high levels of speech perception possible with the CI. It appears the AMI can transmit sufficient spectral cues but with limited temporal cues required for speech understanding. Currently, the AMI uses a CI-based strategy, which was originally designed to stimulate each frequency region along the cochlea with amplitude-modulated pulse trains matching the envelope of the bandpass-filtered sound components. However, it is unclear if this type of stimulation with only a single site within each frequency lamina of the ICC can elicit sufficient temporal cues for speech perception. At least speech understanding in quiet is still possible with envelope cues as low as 50 Hz. Therefore, we investigated how ICC neurons follow the bandpass-filtered envelope structure of natural stimuli in ketamine-anesthetized guinea pigs. We identified a subset of ICC neurons that could closely follow the envelope structure (up to ß100 Hz) of a diverse set of species-specific calls, which was revealed by using a peripheral ear model to estimate the true bandpass-filtered envelopes observed by the brain. Although previous studies have suggested a complex neural transformation from the auditory nerve to the ICC, our data suggest that the brain maintains a robust temporal code in a subset of ICC neurons matching the envelope structure of natural stimuli. Clinically, these findings suggest that a CI-based strategy may still be effective for the AMI if the appropriate neurons are entrained to the envelope of the acoustic stimulus and can transmit sufficient temporal cues to higher centers.
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Affiliation(s)
- Thilo Rode
- Department of Otorhinolaryngology, Hannover Medical University Hannover, Germany
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163
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Yao JD, Bremen P, Middlebrooks JC. Rat primary auditory cortex is tuned exclusively to the contralateral hemifield. J Neurophysiol 2013; 110:2140-51. [PMID: 23945782 DOI: 10.1152/jn.00219.2013] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The rat is a widely used species for study of the auditory system. Psychophysical results from rats have shown an inability to discriminate sound source locations within a lateral hemifield, despite showing fairly sharp near-midline acuity. We tested the hypothesis that those characteristics of the rat's sound localization psychophysics are evident in the characteristics of spatial sensitivity of its cortical neurons. In addition, we sought quantitative descriptions of in vivo spatial sensitivity of cortical neurons that would support development of an in vitro experimental model to study cortical mechanisms of spatial hearing. We assessed the spatial sensitivity of single- and multiple-neuron responses in the primary auditory cortex (A1) of urethane-anesthetized rats. Free-field noise bursts were varied throughout 360° of azimuth in the horizontal plane at sound levels from 10 to 40 dB above neural thresholds. All neurons encountered in A1 displayed contralateral-hemifield spatial tuning in that they responded strongly to contralateral sound source locations, their responses cut off sharply for locations near the frontal midline, and they showed weak or no responses to ipsilateral sources. Spatial tuning was quite stable across a 30-dB range of sound levels. Consistent with rat psychophysical results, a linear discriminator analysis of spike counts exhibited high spatial acuity for near-midline sounds and poor discrimination for off-midline locations. Hemifield spatial tuning is the most common pattern across all mammals tested previously. The homogeneous population of neurons in rat area A1 will make an excellent system for study of the mechanisms underlying that pattern.
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Affiliation(s)
- Justin D Yao
- Department of Neurobiology and Behavior, University of California at Irvine, Irvine, California
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164
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Stolzberg D, Hayes SH, Kashanian N, Radziwon K, Salvi RJ, Allman BL. A novel behavioral assay for the assessment of acute tinnitus in rats optimized for simultaneous recording of oscillatory neural activity. J Neurosci Methods 2013; 219:224-32. [PMID: 23933328 DOI: 10.1016/j.jneumeth.2013.07.021] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2013] [Revised: 07/26/2013] [Accepted: 07/29/2013] [Indexed: 01/05/2023]
Abstract
BACKGROUND Human magneto/electrophysiology studies suggest that the phantom sound of tinnitus arises from spontaneous oscillatory neural activity in auditory cortex; however, in animal models, behavioral techniques suitable for testing this hypothesis in combination with electrophysiology recordings have yet to be evaluated. While electrophysiological studies of tinnitus have been reported in passive, awake animals, these studies fail to control for attentional mechanisms likely to play a role in the perception of tinnitus. NEW METHOD A novel appetitive operant conditioning, two-alternative identification task was developed for detecting acute tinnitus in rats. The procedure optimizes conditions for simultaneously recording oscillatory neural activity while controlling for the attentional state of the animal. RESULTS Tinnitus was detected in six of seven rats following systemic injection with sodium salicylate (200mg/kg IP), a known inducer of tinnitus. Analysis of ongoing local field potentials recorded from chronically implanted electrodes in auditory cortex of a rat reporting tinnitus revealed changes in the spectrum of ongoing neural activity. Comparison with existing method(s): Existing tinnitus-detection methods were not explicitly designed for the simultaneous recording of neural activity. The behavioral method reported here is the first to provide the conditions necessary for obtaining these recordings in chronically implanted rats. CONCLUSIONS The behavioral assay presented here will facilitate research into the neural mechanisms of tinnitus by allowing researchers to compare the electrophysiological data in animals with confirmed tinnitus.
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Affiliation(s)
- Daniel Stolzberg
- Center for Hearing & Deafness, Department of Communicative Disorders and Sciences, University at Buffalo, The State University of New York, Buffalo, NY 14215, USA; Department of Physiology and Pharmacology, Schulich School of Medicine and Dentistry, University of Western Ontario, Ontario N6A 5C1, Canada.
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165
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Abstract
Although training-based auditory cortical plasticity in the adult brain has been previously demonstrated in multiparametric sound domains, neurochemical mechanisms responsible for this form of plasticity are not well understood. In this study, we trained adult rats to identify a target sound stimulus at a specific azimuth angle by using a reward-contingent auditory discrimination task. We found that auditory spatial discrimination training significantly enhanced representation of sound azimuths in the primary auditory cortex, as shown by sharper azimuth-selective curves and more evenly distributed best angles of cortical neurons. Training also facilitated long-term potentiation of field potentials in the primary auditory cortex induced by theta burst stimulation of the white matter. In parallel, there were significant alterations in expression levels of certain cortical GABA(A) and NMDA receptor subunits, resulting in a marked decrease in the level of GABA(A) relative to NMDA receptors. These changes in the expression profile of inhibitory and excitatory neurotransmitter receptor subunits might enhance synaptic transmission, thereby facilitating training-induced cortical plasticity in the spatial domain.
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166
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Takahashi H, Yokota R, Kanzaki R. Response variance in functional maps: neural darwinism revisited. PLoS One 2013; 8:e68705. [PMID: 23874733 PMCID: PMC3708906 DOI: 10.1371/journal.pone.0068705] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2013] [Accepted: 05/31/2013] [Indexed: 11/23/2022] Open
Abstract
The mechanisms by which functional maps and map plasticity contribute to cortical computation remain controversial. Recent studies have revisited the theory of neural Darwinism to interpret the learning-induced map plasticity and neuronal heterogeneity observed in the cortex. Here, we hypothesize that the Darwinian principle provides a substrate to explain the relationship between neuron heterogeneity and cortical functional maps. We demonstrate in the rat auditory cortex that the degree of response variance is closely correlated with the size of its representational area. Further, we show that the response variance within a given population is altered through training. These results suggest that larger representational areas may help to accommodate heterogeneous populations of neurons. Thus, functional maps and map plasticity are likely to play essential roles in Darwinian computation, serving as effective, but not absolutely necessary, structures to generate diverse response properties within a neural population.
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Affiliation(s)
- Hirokazu Takahashi
- Graduate School of Information Science and Technology, The University of Tokyo, Bunkyo-ku, Tokyo, Japan.
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167
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Kim H, Bao S. Experience-dependent overrepresentation of ultrasonic vocalization frequencies in the rat primary auditory cortex. J Neurophysiol 2013; 110:1087-96. [PMID: 23741037 DOI: 10.1152/jn.00230.2013] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Cortical sensory representation is highly adaptive to the environment, and prevalent or behaviorally important stimuli are often overrepresented. One class of such stimuli is species-specific vocalizations. Rats vocalize in the ultrasonic range >30 kHz, but cortical representation of this frequency range has not been systematically examined. We recorded in vivo cortical electrophysiological responses to ultrasonic pure-tone pips, natural ultrasonic vocalizations, and pitch-shifted vocalizations to assess how rats represent this ethologically relevant frequency range. We find that nearly 40% of the primary auditory cortex (AI) represents an octave-wide band of ultrasonic vocalization frequencies (UVFs; 32-64 kHz) compared with <20% for other octave bands <32 kHz. These UVF neurons respond preferentially and reliably to ultrasonic vocalizations. The UVF overrepresentation matures in the cortex before it develops in the central nucleus of inferior colliculus, suggesting a cortical origin and corticofugal influences. Furthermore, the development of cortical UVF overrepresentation depends on early acoustic experience. These results indicate that natural sensory experience causes large-scale cortical map reorganization and improves representations of species-specific vocalizations.
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Affiliation(s)
- Heesoo Kim
- Helen Wills Neuroscience Institute, University of California, Berkeley, CA 94720-3190, USA
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168
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The neuronal responses to repetitive acoustic pulses in different fields of the auditory cortex of awake rats. PLoS One 2013; 8:e64288. [PMID: 23696877 PMCID: PMC3655960 DOI: 10.1371/journal.pone.0064288] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2013] [Accepted: 04/10/2013] [Indexed: 11/19/2022] Open
Abstract
Cortical representation of time-varying features of acoustic signals is a fundamental issue of acoustic processing remaining unresolved. The rat is a widely used animal model for auditory cortical processing. Though some electrophysiological studies have investigated the neural responses to temporal repetitive sounds in the auditory cortex (AC) of rats, most of them were conducted under anesthetized condition. Recently, it has been shown that anesthesia could significantly alter the temporal patterns of neural response. For this reason, we systematically examined the single-unit neural responses to click-trains in the core region of rat AC under awake condition. Consistent with the reports on anesthetized rats, we confirmed the existence of characteristic tonotopic organizations, which were used to divide the AC into anterior auditory field (AAF), primary auditory cortex (A1) and posterior auditory field (PAF). We further found that the neuron's capability to synchronize to the temporal repetitive stimuli progressively decreased along the anterior-to-posterior direction of AC. The median of maximum synchronization rate was 64, 32 and 16 Hz in AAF, A1 and PAF, respectively. On the other hand, the percentage of neurons, which showed non-synchronized responses and could represent the stimulus repetition rate by the mean firing rate, increased from 7% in AAF and A1 to 20% in PAF. These results suggest that the temporal resolution of acoustic processing gradually increases from the anterior to posterior part of AC, and thus there may be a hierarchical stream along this direction of rat AC.
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169
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Pre-attentive, context-specific representation of fear memory in the auditory cortex of rat. PLoS One 2013; 8:e63655. [PMID: 23671691 PMCID: PMC3646040 DOI: 10.1371/journal.pone.0063655] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2012] [Accepted: 04/04/2013] [Indexed: 11/29/2022] Open
Abstract
Neural representation in the auditory cortex is rapidly modulated by both top-down attention and bottom-up stimulus properties, in order to improve perception in a given context. Learning-induced, pre-attentive, map plasticity has been also studied in the anesthetized cortex; however, little attention has been paid to rapid, context-dependent modulation. We hypothesize that context-specific learning leads to pre-attentively modulated, multiplex representation in the auditory cortex. Here, we investigate map plasticity in the auditory cortices of anesthetized rats conditioned in a context-dependent manner, such that a conditioned stimulus (CS) of a 20-kHz tone and an unconditioned stimulus (US) of a mild electrical shock were associated only under a noisy auditory context, but not in silence. After the conditioning, although no distinct plasticity was found in the tonotopic map, tone-evoked responses were more noise-resistive than pre-conditioning. Yet, the conditioned group showed a reduced spread of activation to each tone with noise, but not with silence, associated with a sharpening of frequency tuning. The encoding accuracy index of neurons showed that conditioning deteriorated the accuracy of tone-frequency representations in noisy condition at off-CS regions, but not at CS regions, suggesting that arbitrary tones around the frequency of the CS were more likely perceived as the CS in a specific context, where CS was associated with US. These results together demonstrate that learning-induced plasticity in the auditory cortex occurs in a context-dependent manner.
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170
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Bieszczad KM, Miasnikov AA, Weinberger NM. Remodeling sensory cortical maps implants specific behavioral memory. Neuroscience 2013; 246:40-51. [PMID: 23639876 DOI: 10.1016/j.neuroscience.2013.04.038] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2013] [Revised: 04/12/2013] [Accepted: 04/18/2013] [Indexed: 10/26/2022]
Abstract
Neural mechanisms underlying the capacity of memory to be rich in sensory detail are largely unknown. A candidate mechanism is learning-induced plasticity that remodels the adult sensory cortex. Here, expansion in the primary auditory cortical (A1) tonotopic map of rats was induced by pairing a 3.66-kHz tone with activation of the nucleus basalis, mimicking the effects of natural associative learning. Remodeling of A1 produced de novo specific behavioral memory, but neither memory nor plasticity was consistently at the frequency of the paired tone, which typically decreased in A1 representation. Rather, there was a specific match between individual subjects' area of expansion and the tone that was strongest in each animal's memory, as determined by post-training frequency generalization gradients. These findings provide the first demonstration of a match between the artificial induction of specific neural representational plasticity and artificial induction of behavioral memory. As such, together with prior and present findings for detection, correlation and mimicry of plasticity with the acquisition of memory, they satisfy a key criterion for neural substrates of memory. This demonstrates that directly remodeling sensory cortical maps is sufficient for the specificity of memory formation.
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Affiliation(s)
- K M Bieszczad
- Center for the Neurobiology of Learning and Memory, Department of Neurobiology and Behavior, University of California, Irvine, CA 92697-3800, United States.
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171
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Centanni TM, Engineer CT, Kilgard MP. Cortical speech-evoked response patterns in multiple auditory fields are correlated with behavioral discrimination ability. J Neurophysiol 2013; 110:177-89. [PMID: 23596332 DOI: 10.1152/jn.00092.2013] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Different speech sounds evoke unique patterns of activity in primary auditory cortex (A1). Behavioral discrimination by rats is well correlated with the distinctness of the A1 patterns evoked by individual consonants, but only when precise spike timing is preserved. In this study we recorded the speech-evoked responses in the primary, anterior, ventral, and posterior auditory fields of the rat and evaluated whether activity in these fields is better correlated with speech discrimination ability when spike timing information is included or eliminated. Spike timing information improved consonant discrimination in all four of the auditory fields examined. Behavioral discrimination was significantly correlated with neural discrimination in all four auditory fields. The diversity of speech responses across recordings sites was greater in posterior and ventral auditory fields compared with A1 and anterior auditor fields. These results suggest that, while the various auditory fields of the rat process speech sounds differently, neural activity in each field could be used to distinguish between consonant sounds with accuracy that closely parallels behavioral discrimination. Earlier observations in the visual and somatosensory systems that cortical neurons do not rely on spike timing should be reevaluated with more complex natural stimuli to determine whether spike timing contributes to sensory encoding.
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Affiliation(s)
- T M Centanni
- School of Behavioral and Brain Sciences, University of Texas at Dallas, Richardson, Texas 75080, USA.
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172
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Gaucher Q, Huetz C, Gourévitch B, Laudanski J, Occelli F, Edeline JM. How do auditory cortex neurons represent communication sounds? Hear Res 2013; 305:102-12. [PMID: 23603138 DOI: 10.1016/j.heares.2013.03.011] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/03/2012] [Revised: 03/18/2013] [Accepted: 03/26/2013] [Indexed: 11/30/2022]
Abstract
A major goal in auditory neuroscience is to characterize how communication sounds are represented at the cortical level. The present review aims at investigating the role of auditory cortex in the processing of speech, bird songs and other vocalizations, which all are spectrally and temporally highly structured sounds. Whereas earlier studies have simply looked for neurons exhibiting higher firing rates to particular conspecific vocalizations over their modified, artificially synthesized versions, more recent studies determined the coding capacity of temporal spike patterns, which are prominent in primary and non-primary areas (and also in non-auditory cortical areas). In several cases, this information seems to be correlated with the behavioral performance of human or animal subjects, suggesting that spike-timing based coding strategies might set the foundations of our perceptive abilities. Also, it is now clear that the responses of auditory cortex neurons are highly nonlinear and that their responses to natural stimuli cannot be predicted from their responses to artificial stimuli such as moving ripples and broadband noises. Since auditory cortex neurons cannot follow rapid fluctuations of the vocalizations envelope, they only respond at specific time points during communication sounds, which can serve as temporal markers for integrating the temporal and spectral processing taking place at subcortical relays. Thus, the temporal sparse code of auditory cortex neurons can be considered as a first step for generating high level representations of communication sounds independent of the acoustic characteristic of these sounds. This article is part of a Special Issue entitled "Communication Sounds and the Brain: New Directions and Perspectives".
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Affiliation(s)
- Quentin Gaucher
- Centre de Neurosciences Paris-Sud (CNPS), CNRS UMR 8195, Université Paris-Sud, Bâtiment 446, 91405 Orsay cedex, France
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173
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Profant O, Burianová J, Syka J. The response properties of neurons in different fields of the auditory cortex in the rat. Hear Res 2013; 296:51-9. [DOI: 10.1016/j.heares.2012.11.021] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/04/2012] [Revised: 10/19/2012] [Accepted: 11/18/2012] [Indexed: 10/27/2022]
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174
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Guo F, Intskirveli I, Blake DT, Metherate R. Tone-detection training enhances spectral integration mediated by intracortical pathways in primary auditory cortex. Neurobiol Learn Mem 2013; 101:75-84. [PMID: 23357284 DOI: 10.1016/j.nlm.2013.01.006] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2012] [Revised: 01/11/2013] [Accepted: 01/17/2013] [Indexed: 10/27/2022]
Abstract
Auditory-cued behavioral training can alter neural circuits in primary auditory cortex (A1), but the mechanisms and consequences of experience-dependent cortical plasticity are not fully understood. To address this issue, we trained adult rats to detect a 5 kHz target in order to receive a food reward. After 14 days training we identified three locations within A1: (i) the region representing the characteristic frequency (CF) 5 kHz, (ii) a nearby region with CF ∼10 kHz, and (iii) a more distant region with CF ∼20 kHz. In order to compare functional connectivity in A1 near to, vs. far from, the representation of the target frequency, we placed a 16-channel multiprobe in middle- (∼10 kHz) and high- (∼20 kHz) CF regions and obtained current-source density (CSD) profiles evoked by a range of tone stimuli (CF±1-3 octaves in quarter-octave steps). Our aim was to construct "CSD receptive fields" (CSD RFs) in order to determine the laminar and spectral profile of tone-evoked current sinks, and infer changes to thalamocortical and intracortical inputs. Behavioral training altered CSD RFs at the 10 kHz, but not 20 kHz, site relative to CSD RFs in untrained control animals. At the 10 kHz site, current sinks evoked by the target frequency were enhanced in layer 2/3, but the initial current sink in layer 4 was not altered. The results imply training-induced plasticity along intracortical pathways connecting the target representation with nearby cortical regions. Finally, we related behavioral performance (sensitivity index, d') to CSD responses in individual animals, and found a significant correlation between the development of d' over training and the amplitude of the target-evoked current sink in layer 2/3. The results suggest that plasticity along intracortical pathways is important for auditory learning.
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Affiliation(s)
- Fei Guo
- Department of Neurobiology and Behavior and Center for Hearing Research, University of California, Irvine, CA 92697, USA
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175
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Carcea I, Froemke RC. Cortical plasticity, excitatory-inhibitory balance, and sensory perception. PROGRESS IN BRAIN RESEARCH 2013; 207:65-90. [PMID: 24309251 DOI: 10.1016/b978-0-444-63327-9.00003-5] [Citation(s) in RCA: 78] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Experience shapes the central nervous system throughout life. Structural and functional plasticity confers a remarkable ability on the brain, allowing neural circuits to adequately adapt to dynamic environments. This process can require selective adjustment of many excitatory and inhibitory synapses in an organized manner, in such a way as to enhance representations of behaviorally important sensory stimuli while preserving overall network excitability. The rules and mechanisms that orchestrated these changes across different synapses and throughout neuronal ensembles are beginning to be understood. Here, we review the evidence connecting synaptic plasticity to functional plasticity and perceptual learning, focusing on the roles of various neuromodulatory systems in enabling plasticity of adult neural circuits. However, the challenge remains to appropriately leverage these systems and forms of plasticity to persistently improve perceptual abilities and behavioral performance.
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Affiliation(s)
- Ioana Carcea
- Molecular Neurobiology Program, The Helen and Martin Kimmel Center for Biology and Medicine at the Skirball Institute for Biomolecular Medicine, Department of Physiology and Neuroscience, New York University School of Medicine, New York, NY, USA; Department of Otolaryngology, New York University School of Medicine, New York, NY, USA; Center for Neural Science, New York University, New York, NY, USA
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176
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Storace DA, Higgins NC, Chikar JA, Oliver DL, Read HL. Gene expression identifies distinct ascending glutamatergic pathways to frequency-organized auditory cortex in the rat brain. J Neurosci 2012; 32:15759-68. [PMID: 23136415 PMCID: PMC3752138 DOI: 10.1523/jneurosci.1310-12.2012] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2012] [Revised: 08/07/2012] [Accepted: 09/06/2012] [Indexed: 11/21/2022] Open
Abstract
A conserved feature of sound processing across species is the presence of multiple auditory cortical fields with topographically organized responses to sound frequency. Current organizational schemes propose that the ventral division of the medial geniculate body (MGBv) is a single functionally homogenous structure that provides the primary source of input to all neighboring frequency-organized cortical fields. These schemes fail to account for the contribution of MGBv to functional diversity between frequency-organized cortical fields. Here, we report response property differences for two auditory fields in the rat, and find they have nonoverlapping sources of thalamic input from the MGBv that are distinguished by the gene expression for type 1 vesicular glutamate transporter. These data challenge widely accepted organizational schemes and demonstrate a genetic plurality in the ascending glutamatergic pathways to frequency-organized auditory cortex.
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Affiliation(s)
- Douglas A. Storace
- Department of Psychology, Behavioral Neuroscience Division, University of Connecticut, Storrs, Connecticut 06269
- Department of Neuroscience, University of Connecticut Health Center, Farmington, Connecticut 06030, and
| | - Nathan C. Higgins
- Department of Psychology, Behavioral Neuroscience Division, University of Connecticut, Storrs, Connecticut 06269
| | - Jennifer A. Chikar
- Department of Neuroscience, University of Connecticut Health Center, Farmington, Connecticut 06030, and
| | - Douglas L. Oliver
- Department of Neuroscience, University of Connecticut Health Center, Farmington, Connecticut 06030, and
| | - Heather L. Read
- Department of Psychology, Behavioral Neuroscience Division, University of Connecticut, Storrs, Connecticut 06269
- Biomedical Engineering, University of Connecticut, Storrs, Connecticut 06269
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177
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Noise exposure enhances auditory cortex responses related to hyperacusis behavior. Brain Res 2012; 1485:108-16. [DOI: 10.1016/j.brainres.2012.02.008] [Citation(s) in RCA: 84] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2011] [Revised: 02/01/2012] [Accepted: 02/02/2012] [Indexed: 11/21/2022]
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178
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Functional magnetic resonance imaging of sound pressure level encoding in the rat central auditory system. Neuroimage 2012; 65:119-26. [PMID: 23041525 DOI: 10.1016/j.neuroimage.2012.09.069] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2012] [Revised: 09/27/2012] [Accepted: 09/28/2012] [Indexed: 01/23/2023] Open
Abstract
Intensity is an important physical property of a sound wave and is customarily reported as sound pressure level (SPL). Invasive techniques such as electrical recordings, which typically examine one brain region at a time, have been used to study neuronal encoding of SPL throughout the central auditory system. Non-invasive functional magnetic resonance imaging (fMRI) with large field of view can simultaneously examine multiple auditory structures. We applied fMRI to measure the hemodynamic responses in the rat brain during sound stimulation at seven SPLs over a 72 dB range. This study used a sparse temporal sampling paradigm to reduce the adverse effects of scanner noise. Hemodynamic responses were measured from the central nucleus of the inferior colliculus (CIC), external cortex of the inferior colliculus (ECIC), lateral lemniscus (LL), medial geniculate body (MGB), and auditory cortex (AC). BOLD signal changes generally increase significantly (p<0.001) with SPL and the dependence is monotonic in CIC, ECIC, and LL. The ECIC has higher BOLD signal change than CIC and LL at high SPLs. The difference between BOLD signal changes at high and low SPLs is less in the MGB and AC. This suggests that the SPL dependences of the LL and IC are different from those in the MGB and AC and the SPL dependence of the CIC is different from that of the ECIC. These observations are likely related to earlier observations that neurons with firing rates that increase monotonically with SPL are dominant in the CIC, ECIC, and LL while non-monotonic neurons are dominant in the MGB and AC. Further, the IC's SPL dependence measured in this study is very similar to that measured in our earlier study using the continuous imaging method. Therefore, sparse temporal sampling may not be a prerequisite in auditory fMRI studies of the IC.
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179
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Tonotopic-column-dependent variability of neural encoding in the auditory cortex of rats. Neuroscience 2012; 223:377-87. [DOI: 10.1016/j.neuroscience.2012.07.051] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2012] [Revised: 07/11/2012] [Accepted: 07/19/2012] [Indexed: 11/19/2022]
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180
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Robustness of cortical topography across fields, laminae, anesthetic states, and neurophysiological signal types. J Neurosci 2012; 32:9159-72. [PMID: 22764225 DOI: 10.1523/jneurosci.0065-12.2012] [Citation(s) in RCA: 162] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Topographically organized maps of the sensory receptor epithelia are regarded as cornerstones of cortical organization as well as valuable readouts of diverse biological processes ranging from evolution to neural plasticity. However, maps are most often derived from multiunit activity recorded in the thalamic input layers of anesthetized animals using near-threshold stimuli. Less distinct topography has been described by studies that deviated from the formula above, which brings into question the generality of the principle. Here, we explicitly compared the strength of tonotopic organization at various depths within core and belt regions of the auditory cortex using electrophysiological measurements ranging from single units to delta-band local field potentials (LFP) in the awake and anesthetized mouse. Unit recordings in the middle cortical layers revealed a precise tonotopic organization in core, but not belt, regions of auditory cortex that was similarly robust in awake and anesthetized conditions. In core fields, tonotopy was degraded outside the middle layers or when LFP signals were substituted for unit activity, due to an increasing proportion of recording sites with irregular tuning for pure tones. However, restricting our analysis to clearly defined receptive fields revealed an equivalent tonotopic organization in all layers of the cortical column and for LFP activity ranging from gamma to theta bands. Thus, core fields represent a transition between topographically organized simple receptive field arrangements that extend throughout all layers of the cortical column and the emergence of nontonotopic representations outside the input layers that are further elaborated in the belt fields.
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181
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Kato YX, Furukawa S, Samejima K, Hironaka N, Kashino M. Photosensitive-polyimide based method for fabricating various neural electrode architectures. FRONTIERS IN NEUROENGINEERING 2012; 5:11. [PMID: 22719725 PMCID: PMC3376501 DOI: 10.3389/fneng.2012.00011] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/22/2011] [Accepted: 05/31/2012] [Indexed: 11/13/2022]
Abstract
An extensive photosensitive-polyimide (PSPI)-based method for designing and fabricating various neural electrode architectures was developed. The method aims to broaden the design flexibility and expand the fabrication capability for neural electrodes to improve the quality of recorded signals and integrate other functions. After characterizing PSPI's properties for micromachining processes, we successfully designed and fabricated various neural electrodes even on a non-flat substrate using only one PSPI as an insulation material and without the time-consuming dry etching processes. The fabricated neural electrodes were an electrocorticogram (ECoG) electrode, a mesh intracortical electrode with a unique lattice-like mesh structure to fixate neural tissue, and a guide cannula electrode with recording microelectrodes placed on the curved surface of a guide cannula as a microdialysis probe. In vivo neural recordings using anesthetized rats demonstrated that these electrodes can be used to record neural activities repeatedly without any breakage and mechanical failures, which potentially promises stable recordings for long periods of time. These successes make us believe that this PSPI-based fabrication is a powerful method, permitting flexible design, and easy optimization of electrode architectures for a variety of electrophysiological experimental research with improved neural recording performance.
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Affiliation(s)
- Yasuhiro X Kato
- Brain Science Institute, Tamagawa University, Machida Tokyo, Japan
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182
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Zhang J. Auditory cortex stimulation to suppress tinnitus: mechanisms and strategies. Hear Res 2012; 295:38-57. [PMID: 22683861 DOI: 10.1016/j.heares.2012.05.007] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/04/2012] [Revised: 05/06/2012] [Accepted: 05/14/2012] [Indexed: 01/08/2023]
Abstract
Brain stimulation is an important method used to modulate neural activity and suppress tinnitus. Several auditory and non-auditory brain regions have been targeted for stimulation. This paper reviews recent progress on auditory cortex (AC) stimulation to suppress tinnitus and its underlying neural mechanisms and stimulation strategies. At the same time, the author provides his opinions and hypotheses on both animal and human models. The author also proposes a medial geniculate body (MGB)-thalamic reticular nucleus (TRN)-Gating mechanism to reflect tinnitus-related neural information coming from upstream and downstream projection structures. The upstream structures include the lower auditory brainstem and midbrain structures. The downstream structures include the AC and certain limbic centers. Both upstream and downstream information is involved in a dynamic gating mechanism in the MGB together with the TRN. When abnormal gating occurs at the thalamic level, the spilled-out information interacts with the AC to generate tinnitus. The tinnitus signals at the MGB-TRN-Gating may be modulated by different forms of stimulations including brain stimulation. Each stimulation acts as a gain modulator to control the level of tinnitus signals at the MGB-TRN-Gate. This hypothesis may explain why different types of stimulation can induce tinnitus suppression. Depending on the tinnitus etiology, MGB-TRN-Gating may be different in levels and dynamics, which cause variability in tinnitus suppression induced by different gain controllers. This may explain why the induced suppression of tinnitus by one type of stimulation varies across individual patients.
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Affiliation(s)
- Jinsheng Zhang
- Department of Otolaryngology - Head and Neck Surgery, Wayne State University, School of Medicine, 5E-UHC, 4201 Saint Antoine, Detroit, MI 48201, USA.
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183
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Stolzberg D, Chrostowski M, Salvi RJ, Allman BL. Intracortical circuits amplify sound-evoked activity in primary auditory cortex following systemic injection of salicylate in the rat. J Neurophysiol 2012; 108:200-14. [PMID: 22496535 DOI: 10.1152/jn.00946.2011] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
A high dose of sodium salicylate temporarily induces tinnitus, mild hearing loss, and possibly hyperacusis in humans and other animals. Salicylate has well-established effects on cochlear function, primarily resulting in the moderate reduction of auditory input to the brain. Despite decreased peripheral sensitivity and output, salicylate induces a paradoxical enhancement of the sound-evoked field potential at the level of the primary auditory cortex (A1). Previous electrophysiologic studies have begun to characterize changes in thalamorecipient layers of A1; however, A1 is a complex neural circuit with recurrent intracortical connections. To describe the effects of acute systemic salicylate treatment on both thalamic and intracortical sound-driven activity across layers of A1, we applied current-source density (CSD) analysis to field potentials sampled across cortical layers in the anesthetized rat. CSD maps were normally characterized by a large, short-latency, monosynaptic, thalamically driven sink in granular layers followed by a lower amplitude, longer latency, polysynaptic, intracortically driven sink in supragranular layers. Following systemic administration of salicylate, there was a near doubling of both granular and supragranular sink amplitudes at higher sound levels. The supragranular sink amplitude input/output function changed from becoming asymptotic at approximately 50 dB to sharply nonasymptotic, often dominating the granular sink amplitude at higher sound levels. The supragranular sink also exhibited a significant decrease in peak latency, reflecting an acceleration of intracortical processing of the sound-evoked response. Additionally, multiunit (MU) activity was altered by salicylate; the normally onset/sustained MU response type was transformed into a primarily onset response type in granular and infragranular layers. The results from CSD analysis indicate that salicylate significantly enhances sound-driven response via intracortical circuits.
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Affiliation(s)
- Daniel Stolzberg
- Center for Hearing and Deafness, State University of New York at Buffalo, Buffalo, NY 14214, USA.
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184
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Chen GD, Manohar S, Salvi R. Amygdala hyperactivity and tonotopic shift after salicylate exposure. Brain Res 2012; 1485:63-76. [PMID: 22464181 DOI: 10.1016/j.brainres.2012.03.016] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2012] [Revised: 03/05/2012] [Accepted: 03/06/2012] [Indexed: 10/28/2022]
Abstract
The amygdala, important in forming and storing memories of aversive events, is believed to play a major role in debilitating tinnitus and hyperacusis. To explore this hypothesis, we recorded from the lateral amygdala (LA) and auditory cortex (AC) before and after treating rats with a dose of salicylate that induces tinnitus and hyperacusis-like behavior. Salicylate unexpectedly increased the amplitude of the local field potential (LFP) in the LA making it hyperactive to sounds≥60 dB SPL. Frequency receptive fields (FRFs) of multiunit (MU) clusters in the LA were also dramatically altered by salicylate. Neuronal activity at frequencies below 10 kHz and above 20 kHz was depressed at low intensities, but was greatly enhanced for stimuli between 10 and 20 kHz (frequencies near the pitch of the salicylate-induced tinnitus in the rat). These frequency-dependent changes caused the FRF of many LA neurons to migrate towards 10-20 kHz thereby amplifying activity from this region. To determine if salicylate-induced changes restricted to the LA would remotely affect neural activity in the AC, we used a micropipette to infuse salicylate (20 μl, 2.8 mM) into the amygdala. Local delivery of salicylate to the amygdala significantly increased the amplitude of the LFP recorded in the AC and selectively enhanced the neuronal activity of AC neurons at the mid-frequencies (10-20 kHz), frequencies associated with the tinnitus pitch. Taken together, these results indicate that systemic salicylate treatment can induce hyperactivity and tonotopic shift in the amygdala and infusion of salicylate into the amygdala can profoundly enhance sound-evoked activity in AC, changes likely to increase the perception and emotional salience of tinnitus and loud sounds. This article is part of a Special Issue entitled: Tinnitus Neuroscience.
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Affiliation(s)
- Guang-Di Chen
- Center for Hearing and Deafness, State University of New York at Buffalo, 137 Cary Hall, 3435 Main Street, Buffalo, NY 14214, USA.
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185
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Kimura A, Yokoi I, Imbe H, Donishi T, Kaneoke Y. Auditory thalamic reticular nucleus of the rat: Anatomical nodes for modulation of auditory and cross-modal sensory processing in the loop connectivity between the cortex and thalamus. J Comp Neurol 2012; 520:1457-80. [DOI: 10.1002/cne.22805] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
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186
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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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187
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Bieszczad KM, Weinberger NM. Extinction reveals that primary sensory cortex predicts reinforcement outcome. Eur J Neurosci 2012; 35:598-613. [PMID: 22304434 DOI: 10.1111/j.1460-9568.2011.07974.x] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Primary sensory cortices are traditionally regarded as stimulus analysers. However, studies of associative learning-induced plasticity in the primary auditory cortex (A1) indicate involvement in learning, memory and other cognitive processes. For example, the area of representation of a tone becomes larger for stronger auditory memories and the magnitude of area gain is proportional to the degree that a tone becomes behaviorally important. Here, we used extinction to investigate whether 'behavioral importance' specifically reflects a sound's ability to predict reinforcement (reward or punishment) vs. to predict any significant change in the meaning of a sound. If the former, then extinction should reverse area gains as the signal no longer predicts reinforcement. Rats (n = 11) were trained to bar-press to a signal tone (5.0 kHz) for water-rewards, to induce signal-specific area gains in A1. After subsequent withdrawal of reward, A1 was mapped to determine representational areas. Signal-specific area gains, estimated from a previously established brain-behavior quantitative function, were reversed, supporting the 'reinforcement prediction' hypothesis. Area loss was specific to the signal tone vs. test tones, further indicating that withdrawal of reinforcement, rather than unreinforced tone presentation per se, was responsible for area loss. Importantly, the amount of area loss was correlated with the amount of extinction (r = 0.82, P < 0.01). These findings show that primary sensory cortical representation can encode behavioral importance as a signal's value to predict reinforcement, and that the number of cells tuned to a stimulus can dictate its ability to command behavior.
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Affiliation(s)
- Kasia M Bieszczad
- Department of Neurobiology and Behavior, Center for the Neurobiology of Learning and Memory, University of California, Irvine, CA 92697-3800, USA
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188
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Guo F, Zhang J, Zhu X, Cai R, Zhou X, Sun X. Auditory discrimination training rescues developmentally degraded directional selectivity and restores mature expression of GABA(A) and AMPA receptor subunits in rat auditory cortex. Behav Brain Res 2012; 229:301-7. [PMID: 22306199 DOI: 10.1016/j.bbr.2011.12.041] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2011] [Revised: 12/27/2011] [Accepted: 12/28/2011] [Indexed: 11/25/2022]
Abstract
Auditory frequency discrimination training can remediate deteriorated frequency representations and temporal information processing in the adult primary auditory cortex induced by early post-natal pulsed noise exposure. In this study, we investigated the neural mechanisms underlying the restoration of directional selectivity by auditory spatial discrimination training. Rats exposed to pulsed noise during a post-natal critical period demonstrated reduced auditory directional selectivity but could be successfully trained to identify a target sound stimulus at a specific azimuth angle using a reward-contingent auditory discrimination task (EXP rats). In contrast, rats passively exposed to the training procedure but no reward for correct identification of the azimuth angle (PNR rats) showed no improvement and behavioral performance remained significantly below EXP rats and control (CON) rats reared under a normal sonic environment. The expression levels of GABA(A) receptor subunits α1, α3, β2, and β3, and the AMPA GluR2 subunit were significantly altered in the auditory cortex of untrained noise-raised (NR and PNR) rats compared to age-matched CON rats, while trained noise-raised (EXP) rats exhibited levels of expression not significantly different from CON rats. Thus, reward-contingent sound-azimuth discrimination training may remediate directional selectivity by restoring the proper expression profile of neurotransmitter receptor subunits in the auditory cortex, allowing for normal spatial selectivity by cortical neurons. The development of auditory directional selectivity depends on the regulated expression of these excitatory and inhibitory neurotransmitter receptor subunits; early pulsed noise may disrupt the normal development of directional selectivity by interfering with receptor expression.
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Affiliation(s)
- Fei Guo
- School of Life Science, Key Laboratory of Brain Functional Genomics, Ministry of Education, East China Normal University, 3663 North Zhongshan Road, Shanghai 200062, China
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189
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Smith PH, Uhlrich DJ, Manning KA, Banks MI. Thalamocortical projections to rat auditory cortex from the ventral and dorsal divisions of the medial geniculate nucleus. J Comp Neurol 2012; 520:34-51. [PMID: 21618239 PMCID: PMC3320111 DOI: 10.1002/cne.22682] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The ventral and dorsal medial geniculate (MGV and MGD) constitute the major auditory thalamic subdivisions providing thalamocortical inputs to layer IV and lower layer III of auditory cortex. No quantitative evaluation of this projection is available. Using biotinylated dextran amine (BDA)/biocytin injections, we describe the cortical projection patterns of MGV and MGD cells. In primary auditory cortex the bulk of MGV axon terminals are in layer IV/lower layer III with minor projections to supragranular layers and intermediate levels in infragranular layers. MGD axons project to cortical regions designated posterodorsal (PD) and ventral (VA) showing laminar terminal distributions that are quantitatively similar to the MGV-to-primary cortex terminal distribution. At the electron microscopic level MGV and MGD terminals are non-γ-aminobutyric acid (GABA)ergic with MGD terminals in PD and VA slightly but significantly larger than MGV terminals in primary cortex. MGV/MGD terminals synapse primarily onto non-GABAergic spines/dendrites. A small number synapse on GABAergic structures, contacting large dendrites or cell bodies primarily in the major thalamocortical recipient layers. For MGV projections to primary cortex or MGD projections to PD or VA, the non-GABAergic postsynaptic structures at each site were the same size regardless of whether they were in supragranular, granular, or infragranular layers. However, the population of MGD terminal-recipient structures in VA were significantly larger than the MGD terminal-recipient structures in PD or the MGV terminal-recipient structures in primary cortex. Thus, if terminal and postsynaptic structure size indicate strength of excitation then MGD to VA inputs are strongest, MGD to PD intermediate, and MGV to primary cortex the weakest.
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Affiliation(s)
- Philip H Smith
- Department of Neuroscience, University of Wisconsin School of Medicine and Public Health, Madison, WI 53705, USA.
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190
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Jakkamsetti V, Chang KQ, Kilgard MP. Reorganization in processing of spectral and temporal input in the rat posterior auditory field induced by environmental enrichment. J Neurophysiol 2011; 107:1457-75. [PMID: 22131375 DOI: 10.1152/jn.01057.2010] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Environmental enrichment induces powerful changes in the adult cerebral cortex. Studies in primary sensory cortex have observed that environmental enrichment modulates neuronal response strength, selectivity, speed of response, and synchronization to rapid sensory input. Other reports suggest that nonprimary sensory fields are more plastic than primary sensory cortex. The consequences of environmental enrichment on information processing in nonprimary sensory cortex have yet to be studied. Here we examine physiological effects of enrichment in the posterior auditory field (PAF), a field distinguished from primary auditory cortex (A1) by wider receptive fields, slower response times, and a greater preference for slowly modulated sounds. Environmental enrichment induced a significant increase in spectral and temporal selectivity in PAF. PAF neurons exhibited narrower receptive fields and responded significantly faster and for a briefer period to sounds after enrichment. Enrichment increased time-locking to rapidly successive sensory input in PAF neurons. Compared with previous enrichment studies in A1, we observe a greater magnitude of reorganization in PAF after environmental enrichment. Along with other reports observing greater reorganization in nonprimary sensory cortex, our results in PAF suggest that nonprimary fields might have a greater capacity for reorganization compared with primary fields.
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Affiliation(s)
- Vikram Jakkamsetti
- School of Behavioral and Brain Sciences, University of Texas at Dallas, Richardson, TX 75083, USA
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191
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Sawatari H, Tanaka Y, Takemoto M, Nishimura M, Hasegawa K, Saitoh K, Song WJ. Identification and characterization of an insular auditory field in mice. Eur J Neurosci 2011; 34:1944-52. [DOI: 10.1111/j.1460-9568.2011.07926.x] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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192
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Szymanski FD, Rabinowitz NC, Magri C, Panzeri S, Schnupp JWH. The laminar and temporal structure of stimulus information in the phase of field potentials of auditory cortex. J Neurosci 2011; 31:15787-801. [PMID: 22049422 PMCID: PMC6623019 DOI: 10.1523/jneurosci.1416-11.2011] [Citation(s) in RCA: 72] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2011] [Revised: 08/26/2011] [Accepted: 09/06/2011] [Indexed: 11/21/2022] Open
Abstract
Recent studies have shown that the phase of low-frequency local field potentials (LFPs) in sensory cortices carries a significant amount of information about complex naturalistic stimuli, yet the laminar circuit mechanisms and the aspects of stimulus dynamics responsible for generating this phase information remain essentially unknown. Here we investigated these issues by means of an information theoretic analysis of LFPs and current source densities (CSDs) recorded with laminar multi-electrode arrays in the primary auditory area of anesthetized rats during complex acoustic stimulation (music and broadband 1/f stimuli). We found that most LFP phase information originated from discrete "CSD events" consisting of granular-superficial layer dipoles of short duration and large amplitude, which we hypothesize to be triggered by transient thalamocortical activation. These CSD events occurred at rates of 2-4 Hz during both stimulation with complex sounds and silence. During stimulation with complex sounds, these events reliably reset the LFP phases at specific times during the stimulation history. These facts suggest that the informativeness of LFP phase in rat auditory cortex is the result of transient, large-amplitude events, of the "evoked" or "driving" type, reflecting strong depolarization in thalamo-recipient layers of cortex. Finally, the CSD events were characterized by a small number of discrete types of infragranular activation. The extent to which infragranular regions were activated was stimulus dependent. These patterns of infragranular activations may reflect a categorical evaluation of stimulus episodes by the local circuit to determine whether to pass on stimulus information through the output layers.
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Affiliation(s)
- Francois D. Szymanski
- Department of Robotics, Brain, and Cognitive Sciences, Italian Institute of Technology, 16163 Genova, Italy
- Department of Physiology, Anatomy, and Genetics, University of Oxford, Oxford OX1 3PT, United Kingdom, and
| | - Neil C. Rabinowitz
- Department of Physiology, Anatomy, and Genetics, University of Oxford, Oxford OX1 3PT, United Kingdom, and
| | - Cesare Magri
- Department of Robotics, Brain, and Cognitive Sciences, Italian Institute of Technology, 16163 Genova, Italy
- Max Planck Institute for Biological Cybernetics, 72076 Tübingen, Germany
| | - Stefano Panzeri
- Department of Robotics, Brain, and Cognitive Sciences, Italian Institute of Technology, 16163 Genova, Italy
| | - Jan W. H. Schnupp
- Department of Robotics, Brain, and Cognitive Sciences, Italian Institute of Technology, 16163 Genova, Italy
- Department of Physiology, Anatomy, and Genetics, University of Oxford, Oxford OX1 3PT, United Kingdom, and
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193
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Takahashi H, Yokota R, Funamizu A, Kose H, Kanzaki R. Learning-stage-dependent, field-specific, map plasticity in the rat auditory cortex during appetitive operant conditioning. Neuroscience 2011; 199:243-58. [PMID: 21985937 DOI: 10.1016/j.neuroscience.2011.09.046] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2011] [Revised: 09/21/2011] [Accepted: 09/21/2011] [Indexed: 01/28/2023]
Abstract
Cortical reorganizations during acquisition of motor skills and experience-dependent recovery after deafferentation consist of several distinct phases, in which expansion of receptive fields is followed by the shrinkage and use-dependent refinement. In perceptual learning, however, such non-monotonic, stage-dependent plasticity remains elusive in the sensory cortex. In the present study, microelectrode mapping characterized plasticity in the rat auditory cortex, including primary, anterior, and ventral/suprarhinal auditory fields (A1, AAF, and VAF/SRAF), at the early and late stages of appetitive operant conditioning. We first demonstrate that most plasticity at the early stage was tentative, and that long-lasting plasticity after extended training was able to be categorized into either early- or late-stage-dominant plasticity. Second, training-induced plasticity occurred both locally and globally with a specific temporal order. Conditioned-stimulus (CS) frequency used in the task tended to be locally over-represented in AAF at the early stage and in VAF/SRAF at the late stage. The behavioral relevance of neural responses suggests that the local plasticity also occurred in A1 at the early stage. In parallel, the tone-responsive area globally shrank at the late stage independently of CS frequency, and this shrinkage was also correlated with the behavioral improvements. Thus, the stage-dependent plasticity may commonly underlie cortical reorganization in the perceptual learning, yet the interactions of local and global plasticity have led to more complicated reorganization than previously thought. Field-specific plasticity has important implications for how each field subserves in the learning; for example, consistent with recent notions, A1 should construct filters to better identify auditory objects at the early stage, while VAF/SRAF contribute to hierarchical computation and storage at the late stage.
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Affiliation(s)
- H Takahashi
- Research Center for Advanced Science and Technology, The University of Tokyo, Komaba 4-6-1, Meguro-ku, Tokyo 153-8904, Japan.
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194
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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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195
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Pienkowski M, Eggermont JJ. Sound frequency representation in primary auditory cortex is level tolerant for moderately loud, complex sounds. J Neurophysiol 2011; 106:1016-27. [DOI: 10.1152/jn.00291.2011] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The distribution of neuronal characteristic frequencies over the area of primary auditory cortex (AI) roughly reflects the tonotopic organization of the cochlea. However, because the area of AI activated by any given sound frequency increases erratically with sound level, it has generally been proposed that frequency is represented in AI not with a rate-place code but with some more complex, distributed code. Here, on the basis of both spike and local field potential (LFP) recordings in the anesthetized cat, we show that the tonotopic representation in AI is much more level tolerant when mapped with spectrotemporally dense tone pip ensembles rather than with individually presented tone pips. That is, we show that the tuning properties of individual unit and LFP responses are less variable with sound level under dense compared with sparse stimulation, and that the spatial frequency resolution achieved by the AI neural population at moderate stimulus levels (65 dB SPL) is better with densely than with sparsely presented sounds. This implies that nonlinear processing in the central auditory system can compensate (in part) for the level-dependent coding of sound frequency in the cochlea, and suggests that there may be a functional role for the cortical tonotopic map in the representation of complex sounds.
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Affiliation(s)
- Martin Pienkowski
- Department of Physiology and Pharmacology,
- Department of Psychology, and
| | - Jos J. Eggermont
- Department of Physiology and Pharmacology,
- Department of Psychology, and
- Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada
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196
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Krubitzer L, Campi KL, Cooke DF. All rodents are not the same: a modern synthesis of cortical organization. BRAIN, BEHAVIOR AND EVOLUTION 2011; 78:51-93. [PMID: 21701141 PMCID: PMC3182045 DOI: 10.1159/000327320] [Citation(s) in RCA: 80] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Rodents are a major order of mammals that is highly diverse in distribution and lifestyle. Five suborders, 34 families, and 2,277 species within this order occupy a number of different niches and vary along several lifestyle dimensions such as diel pattern (diurnal vs. nocturnal), terrain niche, and diet. For example, the terrain niche of rodents includes arboreal, aerial, terrestrial, semi-aquatic, burrowing, and rock dwelling. Not surprisingly, the behaviors associated with particular lifestyles are also highly variable and thus the neocortex, which generates these behaviors, has undergone corresponding alterations across species. Studies of cortical organization in species that vary along several dimensions such as terrain niche, diel pattern, and rearing conditions demonstrate that the size and number of cortical fields can be highly variable within this order. The internal organization of a cortical field also reflects lifestyle differences between species and exaggerates behaviorally relevant effectors such as vibrissae, teeth, or lips. Finally, at a cellular level, neuronal number and density varies for the same cortical field in different species and is even different for the same species reared in different conditions (laboratory vs. wild-caught). These very large differences across and within rodent species indicate that there is no generic rodent model. Rather, there are rodent models suited for specific questions regarding the development, function, and evolution of the neocortex.
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Affiliation(s)
- Leah Krubitzer
- Center for Neuroscience, University of California, Davis, Davis, CA 95618, USA.
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197
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Abstract
The mouse sensory neocortex is reported to lack several hallmark features of topographic organization such as ocular dominance and orientation columns in primary visual cortex or fine-scale tonotopy in primary auditory cortex (AI). Here, we re-examined the question of auditory functional topography by aligning ultra-dense receptive field maps from the auditory cortex and thalamus of the mouse in vivo with the neural circuitry contained in the auditory thalamocortical slice in vitro. We observed precisely organized tonotopic maps of best frequency (BF) in the middle layers of AI and the anterior auditory field as well as in the ventral and medial divisions of the medial geniculate body (MGBv and MGBm, respectively). Tracer injections into distinct zones of the BF map in AI retrogradely labeled topographically organized MGBv projections and weaker, mixed projections from MGBm. Stimulating MGBv along the tonotopic axis in the slice produced an orderly shift of voltage-sensitive dye (VSD) signals along the AI tonotopic axis, demonstrating topography in the mouse thalamocortical circuit that is preserved in the slice. However, compared with BF maps of neuronal spiking activity, the topographic order of subthreshold VSD maps was reduced in layer IV and even further degraded in layer II/III. Therefore, the precision of AI topography varies according to the source and layer of the mapping signal. Our findings further bridge the gap between in vivo and in vitro approaches for the detailed cellular study of auditory thalamocortical circuit organization and plasticity in the genetically tractable mouse model.
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198
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Natural restoration of critical period plasticity in the juvenile and adult primary auditory cortex. J Neurosci 2011; 31:5625-34. [PMID: 21490203 DOI: 10.1523/jneurosci.6470-10.2011] [Citation(s) in RCA: 86] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Since its first description >40 years ago, the neurological "critical period" has been predominantly described as an early, plastic postnatal brain development stage that rather abruptly advances to an aplastic or less plastic "adult" stage. Here, we show that chronic exposure of juvenile or adult rats to moderate-level acoustic noise results in a broad reversal of maturational changes that mark the infant-to-adult progression in the primary auditory cortex. In time, noise exposure reinstates critical period plasticity. Cortical changes resulting from noise exposure are again reversed to reestablish a physically and functionally normal adult cortex, by returning animals to natural acoustic environments. These studies show that at least some of neurological changes believed to mark the transition from the infantile to the mature (adult) stage are, by their nature, reversible.
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199
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Lu J, Lobarinas E, Deng A, Goodey R, Stolzberg D, Salvi RJ, Sun W. GABAergic neural activity involved in salicylate-induced auditory cortex gain enhancement. Neuroscience 2011; 189:187-98. [PMID: 21664433 DOI: 10.1016/j.neuroscience.2011.04.073] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2011] [Revised: 04/12/2011] [Accepted: 04/16/2011] [Indexed: 12/31/2022]
Abstract
Although high doses of sodium salicylate impair cochlear function, it paradoxically enhances sound-evoked activity in the auditory cortex (AC) and augments acoustic startle reflex responses, neural and behavioral metrics associated with hyperexcitability and hyperacusis. To explore the neural mechanisms underlying salicylate (SS)-induced hyperexcitability and "increased central gain," we examined the effects of GABA receptor agonists and antagonists on SS-induced hyperexcitability in the AC and startle reflex responses. Consistent with our previous findings, local or systemic application of SS significantly increased the amplitude of sound-evoked AC neural activity, but generally reduced spontaneous activity in the AC. Systemic injection of SS also significantly increased the acoustic startle reflex. S-baclofen or R-baclofen, GABA-B agonists, which suppressed sound-evoked AC neural firing rate and local field potentials, also suppressed the SS-induced enhancement of the AC field potential and the acoustic startle reflex. Local application of vigabatrin, which enhances GABA concentration in the brain, suppressed the SS-induced enhancement of AC firing rate. Systemic injection of vigabatrin also reduced the SS-induced enhancement of acoustic startle reflex. Collectively, these results suggest that the sound-evoked behavioral and neural hyperactivity induced by SS may arise from a SS-induced suppression of GABAergic inhibition in the AC.
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Affiliation(s)
- J Lu
- Center for Hearing and Deafness, Department of Communicative Disorders and Sciences, State University of New York at Buffalo, 3435 Main Street, NY 14214, USA
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200
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Ouda L, Druga R, Syka J. Distribution of SMI-32-immunoreactive neurons in the central auditory system of the rat. Brain Struct Funct 2011; 217:19-36. [PMID: 21656307 DOI: 10.1007/s00429-011-0329-6] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2011] [Accepted: 05/11/2011] [Indexed: 02/02/2023]
Abstract
SMI-32 antibody recognizes a non-phosphorylated epitope of neurofilament proteins, which are thought to be necessary for the maintenance of large neurons with highly myelinated processes. We investigated the distribution and quantity of SMI-32-immunoreactive(-ir) neurons in individual parts of the rat auditory system. SMI-32-ir neurons were present in all auditory structures; however, in most regions they constituted only a minority of all neurons (10-30%). In the cochlear nuclei, a higher occurrence of SMI-32-ir neurons was found in the ventral cochlear nucleus. Within the superior olivary complex, SMI-32-ir cells were particularly abundant in the medial nucleus of the trapezoid body (MNTB), the only auditory region where SMI-32-ir neurons constituted an absolute majority of all neurons. In the inferior colliculus, a region with the highest total number of neurons among the rat auditory subcortical structures, the percentage of SMI-32-ir cells was, in contrast to the MNTB, very low. In the medial geniculate body, SMI-32-ir neurons were prevalent in the ventral division. At the cortical level, SMI-32-ir neurons were found mainly in layers III, V and VI. Within the auditory cortex, it was possible to distinguish the Te1, Te2 and Te3 areas on the basis of the variable numerical density and volumes of SMI-32-ir neurons, especially when the pyramidal cells of layer V were taken into account. SMI-32-ir neurons apparently form a representative subpopulation of neurons in all parts of the rat central auditory system and may belong to both the inhibitory and excitatory systems, depending on the particular brain region.
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Affiliation(s)
- Ladislav Ouda
- Institute of Experimental Medicine, Academy of Sciences of the Czech Republic, Vídeňská 1083, 142 20 Prague, Czech Republic.
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