Tone Frequency Maps and Receptive Fields in the Developing Chinchilla Auditory Cortex

2005 ◽  
Vol 93 (1) ◽  
pp. 454-466 ◽  
Author(s):  
Martin Pienkowski ◽  
Robert V. Harrison
Keyword(s):  
Auditory Cortex ◽  
Receptive Fields ◽  
Sound Stimulation ◽  
Tone Frequency ◽  
Acoustic Environment ◽  
Hearing Sensitivity ◽  
Temporal Complexity ◽  
Ketamine Anesthesia ◽  
Middle Ear Disease ◽  
Cortical Receptive Fields

Single-unit responses to tone pip stimuli were isolated from numerous microelectrode penetrations of auditory cortex (under ketamine anesthesia) in the developing chinchilla ( laniger), a precocious mammal. Results are reported at postnatal day 3 (P3), P15, and P30, and from adult animals. Hearing sensitivity and spike firing rates were mature in the youngest group. The topographic representation of sound frequency (tonotopic map) in primary and secondary auditory cortex was also well ordered and sharply tuned by P3. The spectral-temporal complexity of cortical receptive fields, on the other hand, increased progressively (past P30) to adulthood. The (purported) refinement of initially diffuse tonotopic projections to cortex thus seems to occur in utero in the chinchilla, where external (and maternal) sounds are considerably attenuated and might not contribute to the mechanism(s) involved. This compares well with recent studies of vision, suggesting that the refinement of the retinotopic map does not require external light, but rather waves of (correlated) spontaneous activity on the retina. In contrast, it is most probable that selectivity for more complex sound features, such as frequency stacks and glides, develops under the influence of the postnatal acoustic environment and that inadequate sound stimulation in early development (e.g., due to chronic middle ear disease) impairs the formation of the requisite intracortical (and/or subcortical) circuitry.

Delayed Inhibition in Cortical Receptive Fields and the Discrimination of Complex Stimuli

2005 ◽  
Vol 94 (4) ◽  
pp. 2970-2975 ◽  
Author(s):  
Rajiv Narayan ◽  
Ayla Ergün ◽  
Kamal Sen
Keyword(s):  
Auditory Cortex ◽  
Temporal Structure ◽  
Receptive Fields ◽  
Primary Auditory Cortex ◽  
Natural Sounds ◽  
Functional Roles ◽  
Complex Stimuli ◽  
Animal Vocalizations ◽  
Field L ◽  
Cortical Receptive Fields

Although auditory cortex is thought to play an important role in processing complex natural sounds such as speech and animal vocalizations, the specific functional roles of cortical receptive fields (RFs) remain unclear. Here, we study the relationship between a behaviorally important function: the discrimination of natural sounds and the structure of cortical RFs. We examine this problem in the model system of songbirds, using a computational approach. First, we constructed model neurons based on the spectral temporal RF (STRF), a widely used description of auditory cortical RFs. We focused on delayed inhibitory STRFs, a class of STRFs experimentally observed in primary auditory cortex (ACx) and its analog in songbirds (field L), which consist of an excitatory subregion and a delayed inhibitory subregion cotuned to a characteristic frequency. We quantified the discrimination of birdsongs by model neurons, examining both the dynamics and temporal resolution of discrimination, using a recently proposed spike distance metric (SDM). We found that single model neurons with delayed inhibitory STRFs can discriminate accurately between songs. Discrimination improves dramatically when the temporal structure of the neural response at fine timescales is considered. When we compared discrimination by model neurons with and without the inhibitory subregion, we found that the presence of the inhibitory subregion can improve discrimination. Finally, we modeled a cortical microcircuit with delayed synaptic inhibition, a candidate mechanism underlying delayed inhibitory STRFs, and showed that blocking inhibition in this model circuit degrades discrimination.

scholarly journals Acoustical Enrichment during Early Development Improves Response Reliability in the Adult Auditory Cortex of the Rat

2018 ◽  
Vol 2018 ◽  
pp. 1-11 ◽  
Author(s):  
Zbyněk Bureš ◽  
Kateryna Pysanenko ◽  
Jiří Lindovský ◽  
Josef Syka
Keyword(s):  
Auditory Cortex ◽  
Early Development ◽  
Phase Locking ◽  
Receptive Fields ◽  
Acoustic Environment ◽  
Rat Pups ◽  
Temporal Course ◽  
Rate Coding ◽  
Auditory Experience ◽  
Discharge Patterns

It is well known that auditory experience during early development shapes response properties of auditory cortex (AC) neurons, influencing, for example, tonotopical arrangement, response thresholds and strength, or frequency selectivity. Here, we show that rearing rat pups in a complex acoustically enriched environment leads to an increased reliability of responses of AC neurons, affecting both the rate and the temporal codes. For a repetitive stimulus, the neurons exhibit a lower spike count variance, indicating a more stable rate coding. At the level of individual spikes, the discharge patterns of individual neurons show a higher degree of similarity across stimulus repetitions. Furthermore, the neurons follow more precisely the temporal course of the stimulus, as manifested by improved phase-locking to temporally modulated sounds. The changes are persistent and present up to adulthood. The results document that besides basic alterations of receptive fields presented in our previous study, the acoustic environment during the critical period of postnatal development also leads to a decreased stochasticity and a higher reproducibility of neuronal spiking patterns.

scholarly journals Dissociable influences of primary auditory cortex and the posterior auditory field on neuronal responses in the dorsal zone of auditory cortex

2015 ◽  
Vol 113 (2) ◽  
pp. 475-486
Author(s):  
Melanie A. Kok ◽  
Daniel Stolzberg ◽  
Trecia A. Brown ◽  
Stephen G. Lomber
Keyword(s):  
Auditory Cortex ◽  
Receptive Fields ◽  
Primary Auditory Cortex ◽  
Population Level ◽  
Noise Burst ◽  
Hierarchical Organization ◽  
Neuronal Responses ◽  
Tone Frequency ◽  
Hierarchical Processing ◽  
Auditory Field

Current models of hierarchical processing in auditory cortex have been based principally on anatomical connectivity while functional interactions between individual regions have remained largely unexplored. Previous cortical deactivation studies in the cat have addressed functional reciprocal connectivity between primary auditory cortex (A1) and other hierarchically lower level fields. The present study sought to assess the functional contribution of inputs along multiple stages of the current hierarchical model to a higher order area, the dorsal zone (DZ) of auditory cortex, in the anaesthetized cat. Cryoloops were placed over A1 and posterior auditory field (PAF). Multiunit neuronal responses to noise burst and tonal stimuli were recorded in DZ during cortical deactivation of each field individually and in concert. Deactivation of A1 suppressed peak neuronal responses in DZ regardless of stimulus and resulted in increased minimum thresholds and reduced absolute bandwidths for tone frequency receptive fields in DZ. PAF deactivation had less robust effects on DZ firing rates and receptive fields compared with A1 deactivation, and combined A1/PAF cooling was largely driven by the effects of A1 deactivation at the population level. These results provide physiological support for the current anatomically based model of both serial and parallel processing schemes in auditory cortical hierarchical organization.

Sensory-Motor Interaction in the Primate Auditory Cortex During Self-Initiated Vocalizations

2003 ◽  
Vol 89 (4) ◽  
pp. 2194-2207 ◽  
Author(s):  
Steven J. Eliades ◽  
Xiaoqin Wang
Keyword(s):  
Auditory Cortex ◽  
Cortical Neurons ◽  
Vocal Communication ◽  
Dynamic Range ◽  
Common Marmoset ◽  
Acoustic Environment ◽  
Hearing Sensitivity ◽  
Sensory Motor ◽  
Excitatory Responses ◽  
Motor Interaction

Little is known about sensory-motor interaction in the auditory cortex of primates at the level of single neurons and its role in supporting vocal communication. The present study investigated single-unit activities in the auditory cortex of a vocal primate, the common marmoset ( Callithrix jacchus), during self-initiated vocalizations. We found that 1) self-initiated vocalizations resulted in suppression of neural discharges in a majority of auditory cortical neurons. The vocalization-induced inhibition suppressed both spontaneous and stimulus-driven discharges. Suppressed units responded poorly to external acoustic stimuli during vocalization. 2) Vocalization-induced suppression began several hundred milliseconds prior to the onset of vocalization. 3) The suppression of cortical discharges reduced neural firings to below the rates expected from a unit's rate-level function, adjusted for known subcortical attenuation, and therefore was likely not entirely caused by subcortical attenuation mechanisms. 4) A smaller population of auditory cortical neurons showed increased discharges during self-initiated vocalizations. This vocalization-related excitation began after the onset of vocalization and is likely the result of acoustic feedback. Units showing this excitation responded nearly normally to external stimuli during vocalization. Based on these findings, we propose that the suppression of auditory cortical neurons, possibly originating from cortical vocal production centers, acts to increase the dynamic range of cortical responses to vocalization feedback for self monitoring. The excitatory responses, on the other hand, likely play a role in maintaining hearing sensitivity to the external acoustic environment during vocalization.

Frequency-specific adaptation in human auditory cortex depends on the spectral variance in the acoustic stimulation

2013 ◽  
Vol 109 (8) ◽  
pp. 2086-2096 ◽  
Author(s):  
Björn Herrmann ◽  
Molly J. Henry ◽  
Jonas Obleser
Keyword(s):  
Auditory Cortex ◽  
Event Related Potentials ◽  
Acoustic Stimulation ◽  
Neural Adaptation ◽  
Tone Frequency ◽  
Acoustic Environment ◽  
Response Properties ◽  
Related Potentials ◽  
Spectral Variance ◽  
Human Participants

In auditory cortex, activation and subsequent adaptation is strongest for regions responding best to a stimulated tone frequency and less for regions responding best to other frequencies. Previous attempts to characterize the spread of neural adaptation in humans investigated the auditory cortex N1 component of the event-related potentials. Importantly, however, more recent studies in animals show that neural response properties are not independent of the stimulation context. To link these findings in animals to human scalp potentials, we investigated whether contextual factors of the acoustic stimulation, namely, spectral variance, affect the spread of neural adaptation. Electroencephalograms were recorded while human participants listened to random tone sequences varying in spectral variance (narrow vs. wide). Spread of adaptation was investigated by modeling single-trial neural adaptation and subsequent recovery based on the spectro-temporal stimulation history. Frequency-specific neural responses were largest on the N1 component, and the modeled neural adaptation indices were strongly predictive of trial-by-trial amplitude variations. Yet the spread of adaption varied depending on the spectral variance in the stimulation, such that adaptation spread was broadened for tone sequences with wide spectral variance. Thus the present findings reveal context-dependent auditory cortex adaptation and point toward a flexibly adjusting auditory system that changes its response properties with the spectral requirements of the acoustic environment.

Intracortical Pathways Determine Breadth of Subthreshold Frequency Receptive Fields in Primary Auditory Cortex

2004 ◽  
Vol 91 (6) ◽  
pp. 2551-2567 ◽  
Author(s):  
Simranjit Kaur ◽  
Ronit Lazar ◽  
Raju Metherate
Keyword(s):  
Receptive Field ◽  
Auditory Cortex ◽  
Receptive Fields ◽  
Field Potential ◽  
Primary Auditory Cortex ◽  
Response Threshold ◽  
Complex Stimuli ◽  
Cortical Receptive Fields ◽  
Local Field Potential Lfp ◽  
Integrated Responses

To examine the basis of frequency receptive fields in auditory cortex (ACx), we have recorded intracellular (whole cell) and extracellular (local field potential, LFP) responses to tones in anesthetized rats. Frequency receptive fields derived from excitatory postsynaptic potentials (EPSPs) and LFPs from the same location resembled each other in terms of characteristic frequency (CF) and breadth of tuning, suggesting that LFPs reflect local synaptic (including subthreshold) activity. Subthreshold EPSP and LFP receptive fields were remarkably broad, often spanning five octaves (the maximum tested) at moderate intensities (40–50 dB above threshold). To identify receptive-field features that are generated intracortically, we microinjected the GABAA receptor agonist muscimol (0.2–5.1 mM, 1–5 μl) into ACx. Muscimol dramatically reduced LFP amplitude and reduced receptive-field bandwidth, implicating intracortical contributions to these features but had lesser effects on CF response threshold or onset latency, suggesting minimal loss of thalamocortical input. Reversal of muscimol's inhibition preferentially at the recording site by diffusion from the recording pipette of the GABAA receptor antagonist picrotoxin (0.01–100 μM) disinhibited responses to CF stimuli more than responses to spectrally distant, non-CF stimuli. We propose that thalamocortical and intracortical pathways preferentially contribute to responses evoked by CF and non-CF stimuli, respectively, and that intracortical projections linking frequency representations determine the breadth of receptive fields in primary ACx. Broad, subthreshold receptive fields may distinguish ACx from subcortical auditory relay nuclei, promote integrated responses to spectrotemporally complex stimuli, and provide a substrate for plasticity of cortical receptive fields and maps.

scholarly journals Organization of Inhibitory Frequency Receptive Fields in Cat Primary Auditory Cortex

1999 ◽  
Vol 82 (5) ◽  
pp. 2358-2371 ◽  
Author(s):  
M. L. Sutter ◽  
C. E. Schreiner ◽  
M. McLean ◽  
K. N. O'connor ◽  
W. C. Loftus
Keyword(s):  
Auditory Cortex ◽  
Regional Differences ◽  
Receptive Fields ◽  
Primary Auditory Cortex ◽  
Inhibitory Response ◽  
Neuronal Responses ◽  
Acoustic Environment ◽  
High Incidence ◽  
Auditory Systems ◽  
Spectral Patterns

Based on properties of excitatory frequency (spectral) receptive fields (esRFs), previous studies have indicated that cat primary auditory cortex (A1) is composed of functionally distinct dorsal and ventral subdivisions. Dorsal A1 (A1d) has been suggested to be involved in analyzing complex spectral patterns, whereas ventral A1 (A1v) appears better suited for analyzing narrowband sounds. However, these studies were based on single-tone stimuli and did not consider how neuronal responses to tones are modulated when the tones are part of a more complex acoustic environment. In the visual and peripheral auditory systems, stimulus components outside of the esRF can exert strong modulatory effects on responses. We investigated the organization of inhibitory frequency regions outside of the pure-tone esRF in single neurons in cat A1. We found a high incidence of inhibitory response areas (in 95% of sampled neurons) and a wide variety in the structure of inhibitory bands ranging from a single band to more than four distinct inhibitory regions. Unlike the auditory nerve where most fibers possess two surrounding “lateral” suppression bands, only 38% of A1 cells had this simple structure. The word lateral is defined in this sense to be inhibition or suppression that extends beyond the low- and high-frequency borders of the esRF. Regional differences in the distribution of inhibitory RF structure across A1 were evident. In A1d, only 16% of the cells had simple two-banded lateral RF organization, whereas 50% of A1v cells had this organization. This nonhomogeneous topographic distribution of inhibitory properties is consistent with the hypothesis that A1 is composed of at least two functionally distinct subdivisions that may be part of different auditory cortical processing streams.

Adaptive Changes in Cortical Receptive Fields Induced by Attention to Complex Sounds

2007 ◽  
Vol 98 (4) ◽  
pp. 2337-2346 ◽  
Author(s):  
Jonathan B. Fritz ◽  
Mounya Elhilali ◽  
Shihab A. Shamma
Keyword(s):  
Receptive Field ◽  
Cortical Plasticity ◽  
Matched Filter ◽  
Receptive Fields ◽  
Primary Auditory Cortex ◽  
Population Level ◽  
Comb Filter ◽  
Tone Frequency ◽  
Complex Sounds ◽  
Cortical Receptive Fields

Receptive fields in primary auditory cortex (A1) can be rapidly and adaptively reshaped to enhance responses to salient frequency cues when using single tones as targets. To explore receptive field changes to more complex spectral patterns, we trained ferrets to detect variable, multitone targets in the context of background, rippled noise. Recordings from A1 of behaving ferrets showed a consistent pattern of plasticity, at both the single-neuron level and the population level, with enhancement for each component tone frequency and suppression for intertone frequencies. Plasticity was strongest near neuronal best frequency, rapid in onset, and slow to fade. Although attention may trigger cortical plasticity, the receptive field changes persisted after the behavioral task was completed. The observed comb filter plasticity is an example of an adaptive contrast matched filter, which may generally improve discriminability between foreground and background sounds and, we conjecture, may predict A1 cortical plasticity for any complex spectral target.

scholarly journals Tinnitus, Diminished Sound-Level Tolerance, and Elevated Auditory Activity in Humans With Clinically Normal Hearing Sensitivity

2010 ◽  
Vol 104 (6) ◽  
pp. 3361-3370 ◽  
Author(s):  
Jianwen Wendy Gu ◽  
Christopher F. Halpin ◽  
Eui-Cheol Nam ◽  
Robert A. Levine ◽  
Jennifer R. Melcher
Keyword(s):  
Auditory Cortex ◽  
Primary Auditory Cortex ◽  
Normal Hearing ◽  
Sound Level ◽  
Cortical Activation ◽  
Auditory Midbrain ◽  
Sound Stimulation ◽  
Hearing Sensitivity ◽  
Clinically Normal ◽  
Hearing Thresholds

Phantom sensations and sensory hypersensitivity are disordered perceptions that characterize a variety of intractable conditions involving the somatosensory, visual, and auditory modalities. We report physiological correlates of two perceptual abnormalities in the auditory domain: tinnitus, the phantom perception of sound, and hyperacusis, a decreased tolerance of sound based on loudness. Here, subjects with and without tinnitus, all with clinically normal hearing thresholds, underwent 1) behavioral testing to assess sound-level tolerance and 2) functional MRI to measure sound-evoked activation of central auditory centers. Despite receiving identical sound stimulation levels, subjects with diminished sound-level tolerance (i.e., hyperacusis) showed elevated activation in the auditory midbrain, thalamus, and primary auditory cortex compared with subjects with normal tolerance. Primary auditory cortex, but not subcortical centers, showed elevated activation specifically related to tinnitus. The results directly link hyperacusis and tinnitus to hyperactivity within the central auditory system. We hypothesize that the tinnitus-related elevations in cortical activation may reflect undue attention drawn to the auditory domain, an interpretation consistent with the lack of tinnitus-related effects subcortically where activation is less potently modulated by attentional state. The data strengthen, at a mechanistic level, analogies drawn previously between tinnitus/hyperacusis and other, nonauditory disordered perceptions thought to arise from neural hyperactivity such as chronic neuropathic pain and photophobia.

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