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1.
PLoS One ; 15(9): e0239487, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32976532

RESUMO

BACKGROUND: For patients with single-sided deafness (SSD), restoration of binaural function via cochlear implant (CI) has been shown to improve speech understanding in noise. The objective of this study was to investigate changes in behavioral performance and cortical auditory responses following cochlear implantation. DESIGN: Prospective longitudinal study. SETTING: Tertiary referral center. METHODS: Six adults with SSD were tested before and 12 months post-activation of the CI. Six normal hearing (NH) participants served as experimental controls. Speech understanding in noise was evaluated for various spatial conditions. Cortical auditory evoked potentials were recorded with /ba/ stimuli in quiet and in noise. Global field power and responses at Cz were analyzed. RESULTS: Speech understanding in noise significantly improved with the CI when speech was presented to the CI ear and noise to the normal ear (p<0.05), but remained poorer than that of NH controls (p<0.05). N1 peak amplitude measure in noise significantly increased after CI activation (p<0.05), but remained lower than that of NH controls (p<0.05) at 12 months. After 12 months of CI experience, cortical responses in noise became more comparable between groups. CONCLUSION: Binaural restoration in SSD patients via cochlear implantation improved speech performance noise and cortical responses. While behavioral performance and cortical auditory responses improved, SSD-CI outcomes remained poorer than that of NH controls in most cases, suggesting only partial restoration of binaural hearing.


Assuntos
Córtex Auditivo/fisiologia , Surdez/fisiopatologia , Perda Auditiva Unilateral/fisiopatologia , Percepção da Fala/fisiologia , Fala/fisiologia , Idoso , Implante Coclear/métodos , Implantes Cocleares , Compreensão/fisiologia , Potenciais Evocados Auditivos/fisiologia , Feminino , Audição/fisiologia , Perda Auditiva Neurossensorial/fisiopatologia , Testes Auditivos/métodos , Humanos , Estudos Longitudinais , Masculino , Pessoa de Meia-Idade , Ruído , Estudos Prospectivos , Localização de Som/fisiologia
2.
Nat Commun ; 11(1): 4361, 2020 08 31.
Artigo em Inglês | MEDLINE | ID: mdl-32868773

RESUMO

The sensory responses of cortical neuronal populations following training have been extensively studied. However, the spike firing properties of individual cortical neurons following training remain unknown. Here, we have combined two-photon Ca2+ imaging and single-cell electrophysiology in awake behaving mice following auditory associative training. We find a sparse set (~5%) of layer 2/3 neurons in the primary auditory cortex, each of which reliably exhibits high-rate prolonged burst firing responses to the trained sound. Such bursts are largely absent in the auditory cortex of untrained mice. Strikingly, in mice trained with different multitone chords, we discover distinct subsets of neurons that exhibit bursting responses specifically to a chord but neither to any constituent tone nor to the other chord. Thus, our results demonstrate an integrated representation of learned complex sounds in a small subset of cortical neurons.


Assuntos
Córtex Auditivo/fisiologia , Percepção Auditiva/fisiologia , Neurônios/fisiologia , Estimulação Acústica/métodos , Córtex Auditivo/citologia , Sinalização do Cálcio , Eletrofisiologia/métodos , Aprendizagem/fisiologia , Microscopia de Fluorescência por Excitação Multifotônica/métodos , Neurônios/metabolismo , Análise de Célula Única/métodos
3.
PLoS Comput Biol ; 16(8): e1008152, 2020 08.
Artigo em Inglês | MEDLINE | ID: mdl-32853256

RESUMO

A repeating triplet-sequence ABA- of non-overlapping brief tones, A and B, is a valued paradigm for studying auditory stream formation and the cocktail party problem. The stimulus is "heard" either as a galloping pattern (integration) or as two interleaved streams (segregation); the initial percept is typically integration then followed by spontaneous alternations between segregation and integration, each being dominant for a few seconds. The probability of segregation grows over seconds, from near-zero to a steady value, defining the buildup function, BUF. Its stationary level increases with the difference in tone frequencies, DF, and the BUF rises faster. Percept durations have DF-dependent means and are gamma-like distributed. Behavioral and computational studies usually characterize triplet streaming either during alternations or during buildup. Here, our experimental design and modeling encompass both. We propose a pseudo-neuromechanistic model that incorporates spiking activity in primary auditory cortex, A1, as input and resolves perception along two network-layers downstream of A1. Our model is straightforward and intuitive. It describes the noisy accumulation of evidence against the current percept which generates switches when reaching a threshold. Accumulation can saturate either above or below threshold; if below, the switching dynamics resemble noise-induced transitions from an attractor state. Our model accounts quantitatively for three key features of data: the BUFs, mean durations, and normalized dominance duration distributions, at various DF values. It describes perceptual alternations without competition per se, and underscores that treating triplets in the sequence independently and averaging across trials, as implemented in earlier widely cited studies, is inadequate.


Assuntos
Córtex Auditivo/fisiologia , Estimulação Acústica , Percepção Auditiva , Feminino , Humanos , Masculino
4.
PLoS One ; 15(7): e0235310, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32697776

RESUMO

BACKGROUND: Auditory steady-state responses (ASSRs) are ongoing evoked brain responses to continuous auditory stimuli that play a role for auditory processing of complex sounds and speech perception. Transient auditory event-related responses (AERRs) have previously been recorded using fetal magnetoencephalography (fMEG) but involve different neurological pathways. Previous studies in children and adults demonstrated that the cortical components of the ASSR are significantly affected by state of consciousness and by maturational changes in neonates and young infants. To our knowledge, this is the first study to investigate ASSRs in human fetuses. METHODS: 47 fMEG sessions were conducted with 24 healthy pregnant women in three gestational age groups (30-32 weeks, 33-35 weeks and 36-39 weeks). The stimulation consisted of amplitude-modulated (AM) tones with a duration of one second, a carrier frequency (CF) of 500 Hz and a modulation frequency (MF) of 27 Hz or 42 Hz. Both tones were presented in a random order with equal probability adding up to 80-100 repetitions per tone. The ASSR across trials was quantified by assessing phase synchrony in the cortical signals at the stimulation frequency. RESULTS AND CONCLUSION: Ten out of 47 recordings were excluded due to technical problems or maternal movements. Analysis of the included 37 fetal recordings revealed a statistically significant response for the phase coherence between trials for the MF of 27 Hz but not for 42 Hz. An exploratory subgroup analysis moreover suggested an advantage in detectability for fetal behavioral state 2F (active asleep) compared to 1F (quiet asleep) detected using fetal heart rate. In conclusion, this pilot study is the first description of a method to detect human ASSRs in fetuses. The findings warrant further investigations of the developing fetal brain.


Assuntos
Córtex Auditivo/fisiologia , Encéfalo/fisiologia , Potenciais Evocados Auditivos/fisiologia , Magnetoencefalografia , Córtex Auditivo/diagnóstico por imagem , Percepção Auditiva/fisiologia , Encéfalo/diagnóstico por imagem , Pré-Escolar , Eletroencefalografia , Feminino , Feto/diagnóstico por imagem , Feto/fisiologia , Humanos , Lactente , Recém-Nascido , Masculino , Gravidez
5.
PLoS One ; 15(7): e0235770, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32639987

RESUMO

In real music, the original melody may appear intact, with little elaboration only, or significantly modified. Since a melody is most easily perceived in music, hearing significantly modified melody may change a brain connectivity. Mozart KV 265 is comprised of a theme with an original melody of "Twinkle Twinkle Little Star" and its significant variations. We studied whether effective connectivity changes with significantly modified melody, between bilateral inferior frontal gyri (IFGs) and Heschl's gyri (HGs) using magnetoencephalography (MEG). Among the 12 connectivities, the connectivity from the left IFG to the right HG was consistently increased with significantly modified melody compared to the original melody in 2 separate sets of the same rhythmic pattern with different melody (p = 0.005 and 0.034, Bonferroni corrected). Our findings show that the modification of an original melody in a real music changes the brain connectivity.


Assuntos
Córtex Auditivo/fisiologia , Percepção Auditiva , Conectoma , Música , Córtex Pré-Frontal/fisiologia , Adulto , Encéfalo/fisiologia , Feminino , Humanos , Magnetoencefalografia , Masculino , Rede Nervosa/fisiologia , Adulto Jovem
6.
PLoS Comput Biol ; 16(7): e1007992, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-32614826

RESUMO

Understanding how the human brain processes auditory input remains a challenge. Traditionally, a distinction between lower- and higher-level sound features is made, but their definition depends on a specific theoretical framework and might not match the neural representation of sound. Here, we postulate that constructing a data-driven neural model of auditory perception, with a minimum of theoretical assumptions about the relevant sound features, could provide an alternative approach and possibly a better match to the neural responses. We collected electrocorticography recordings from six patients who watched a long-duration feature film. The raw movie soundtrack was used to train an artificial neural network model to predict the associated neural responses. The model achieved high prediction accuracy and generalized well to a second dataset, where new participants watched a different film. The extracted bottom-up features captured acoustic properties that were specific to the type of sound and were associated with various response latency profiles and distinct cortical distributions. Specifically, several features encoded speech-related acoustic properties with some features exhibiting shorter latency profiles (associated with responses in posterior perisylvian cortex) and others exhibiting longer latency profiles (associated with responses in anterior perisylvian cortex). Our results support and extend the current view on speech perception by demonstrating the presence of temporal hierarchies in the perisylvian cortex and involvement of cortical sites outside of this region during audiovisual speech perception.


Assuntos
Córtex Auditivo/fisiologia , Percepção Auditiva , Modelos Neurológicos , Redes Neurais de Computação , Som , Adolescente , Adulto , Mapeamento Encefálico/métodos , Eletrocorticografia , Feminino , Humanos , Masculino , Filmes Cinematográficos , Fonética , Processamento de Sinais Assistido por Computador , Fala/fisiologia , Percepção da Fala , Fatores de Tempo , Adulto Jovem
7.
PLoS Comput Biol ; 16(7): e1008016, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-32716912

RESUMO

The mammalian sensory cortex is composed of multiple types of inhibitory and excitatory neurons, which form sophisticated microcircuits for processing and transmitting sensory information. Despite rapid progress in understanding the function of distinct neuronal populations, the parameters of connectivity that are required for the function of these microcircuits remain unknown. Recent studies found that two most common inhibitory interneurons, parvalbumin- (PV) and somatostatin-(SST) positive interneurons control sound-evoked responses, temporal adaptation and network dynamics in the auditory cortex (AC). These studies can inform our understanding of parameters for the connectivity of excitatory-inhibitory cortical circuits. Specifically, we asked whether a common microcircuit can account for the disparate effects found in studies by different groups. By starting with a cortical rate model, we find that a simple current-compensating mechanism accounts for the experimental findings from multiple groups. They key mechanisms are two-fold. First, PVs compensate for reduced SST activity when thalamic inputs are strong with less compensation when thalamic inputs are weak. Second, SSTs are generally disinhibited by reduced PV activity regardless of thalamic input strength. These roles are augmented by plastic synapses. These roles reproduce the differential effects of PVs and SSTs in stimulus-specific adaptation, forward suppression and tuning-curve adaptation, as well as the influence of PVs on feedforward functional connectivity in the circuit. This circuit exhibits a balance of inhibitory and excitatory currents that persists on stimulation. This approach brings together multiple findings from different laboratories and identifies a circuit that can be used in future studies of upstream and downstream sensory processing.


Assuntos
Córtex Auditivo/fisiologia , Biologia Computacional , Interneurônios/fisiologia , Modelos Neurológicos , Optogenética , Algoritmos , Animais , Simulação por Computador , Humanos , Interneurônios/classificação , Sinapses/fisiologia , Tálamo/fisiologia , Fatores de Tempo
8.
PLoS One ; 15(7): e0236760, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32726372

RESUMO

The neural mechanisms underlying forward suppression in the auditory cortex remain a puzzle. Little attention is paid to thalamic contribution despite the important fact that the thalamus gates upstreaming information to the auditory cortex. This study compared the time courses of forward suppression in the auditory thalamus, thalamocortical inputs and cortex using the two-tone stimulus paradigm. The preceding and succeeding tones were 20-ms long. Their frequency and amplitude were set at the characteristic frequency and 20 dB above the minimum threshold of given neurons, respectively. In the ventral division of the medial geniculate body of the thalamus, we found that the duration of complete forward suppression was about 75 ms and the duration of partial suppression was from 75 ms to about 300 ms after the onset of the preceding tone. We also found that during the partial suppression period, the responses to the succeeding tone were further suppressed in the primary auditory cortex. The forward suppression of thalamocortical field excitatory postsynaptic potentials was between those of thalamic and cortical neurons but much closer to that of thalamic ones. Our results indicate that early suppression in the cortex could result from complete suppression in the thalamus whereas later suppression may involve thalamocortical and intracortical circuitry. This suggests that the complete suppression that occurs in the thalamus provides the cortex with a "silence" window that could potentially benefit cortical processing and/or perception of the information carried by the preceding sound.


Assuntos
Córtex Auditivo/fisiologia , Potenciais Pós-Sinápticos Inibidores , Tálamo/fisiologia , Animais , Córtex Auditivo/citologia , Potenciais Pós-Sinápticos Excitadores , Feminino , Corpos Geniculados/citologia , Corpos Geniculados/fisiologia , Camundongos , Camundongos Endogâmicos C57BL , Neurônios/citologia , Tálamo/citologia
9.
PLoS Comput Biol ; 16(6): e1007558, 2020 06.
Artigo em Inglês | MEDLINE | ID: mdl-32559204

RESUMO

The auditory neural code is resilient to acoustic variability and capable of recognizing sounds amongst competing sound sources, yet, the transformations enabling noise robust abilities are largely unknown. We report that a hierarchical spiking neural network (HSNN) optimized to maximize word recognition accuracy in noise and multiple talkers predicts organizational hierarchy of the ascending auditory pathway. Comparisons with data from auditory nerve, midbrain, thalamus and cortex reveals that the optimal HSNN predicts several transformations of the ascending auditory pathway including a sequential loss of temporal resolution and synchronization ability, increasing sparseness, and selectivity. The optimal organizational scheme enhances performance by selectively filtering out noise and fast temporal cues such as voicing periodicity, that are not directly relevant to the word recognition task. An identical network arranged to enable high information transfer fails to predict auditory pathway organization and has substantially poorer performance. Furthermore, conventional single-layer linear and nonlinear receptive field networks that capture the overall feature extraction of the HSNN fail to achieve similar performance. The findings suggest that the auditory pathway hierarchy and its sequential nonlinear feature extraction computations enhance relevant cues while removing non-informative sources of noise, thus enhancing the representation of sounds in noise impoverished conditions.


Assuntos
Córtex Auditivo/fisiologia , Vias Auditivas/fisiologia , Percepção Auditiva , Idioma , Reconhecimento Fisiológico de Modelo , Estimulação Acústica , Acústica , Encéfalo/fisiologia , Mapeamento Encefálico , Simulação por Computador , Humanos , Modelos Neurológicos , Rede Nervosa , Neurônios , Ruído , Razão Sinal-Ruído , Som
10.
Nat Neurosci ; 23(8): 992-1003, 2020 08.
Artigo em Inglês | MEDLINE | ID: mdl-32572235

RESUMO

Basal forebrain cholinergic neurons (BFCNs) modulate synaptic plasticity, cortical processing, brain states and oscillations. However, whether distinct types of BFCNs support different functions remains unclear. Therefore, we recorded BFCNs in vivo, to examine their behavioral functions, and in vitro, to study their intrinsic properties. We identified two distinct types of BFCNs that differ in their firing modes, synchronization properties and behavioral correlates. Bursting cholinergic neurons (Burst-BFCNs) fired synchronously, phase-locked to cortical theta activity and fired precisely timed bursts after reward and punishment. Regular-firing cholinergic neurons (Reg-BFCNs) were found predominantly in the posterior basal forebrain, displayed strong theta rhythmicity and responded with precise single spikes after behavioral outcomes. In an auditory detection task, synchronization of Burst-BFCNs to the auditory cortex predicted the timing of behavioral responses, whereas tone-evoked cortical coupling of Reg-BFCNs predicted correct detections. We propose that differential recruitment of two basal forebrain cholinergic neuron types generates behavior-specific cortical activation.


Assuntos
Prosencéfalo Basal/fisiologia , Neurônios Colinérgicos/fisiologia , Sincronização Cortical/fisiologia , Potenciais de Ação/fisiologia , Animais , Córtex Auditivo/fisiologia , Camundongos , Plasticidade Neuronal/fisiologia , Ritmo Teta/fisiologia
11.
Nat Commun ; 11(1): 3117, 2020 06 19.
Artigo em Inglês | MEDLINE | ID: mdl-32561726

RESUMO

On-line comprehension of natural speech requires segmenting the acoustic stream into discrete linguistic elements. This process is argued to rely on theta-gamma oscillation coupling, which can parse syllables and encode them in decipherable neural activity. Speech comprehension also strongly depends on contextual cues that help predicting speech structure and content. To explore the effects of theta-gamma coupling on bottom-up/top-down dynamics during on-line syllable identification, we designed a computational model (Precoss-predictive coding and oscillations for speech) that can recognise syllable sequences in continuous speech. The model uses predictions from internal spectro-temporal representations of syllables and theta oscillations to signal syllable onsets and duration. Syllable recognition is best when theta-gamma coupling is used to temporally align spectro-temporal predictions with the acoustic input. This neurocomputational modelling work demonstrates that the notions of predictive coding and neural oscillations can be brought together to account for on-line dynamic sensory processing.


Assuntos
Córtex Auditivo/fisiologia , Ritmo Gama/fisiologia , Modelos Neurológicos , Percepção da Fala/fisiologia , Ritmo Teta/fisiologia , Estimulação Acústica , Compreensão/fisiologia , Simulação por Computador , Sinais (Psicologia) , Humanos , Fonética
12.
J Neurosci ; 40(27): 5228-5246, 2020 07 01.
Artigo em Inglês | MEDLINE | ID: mdl-32444386

RESUMO

Humans and animals maintain accurate sound discrimination in the presence of loud sources of background noise. It is commonly assumed that this ability relies on the robustness of auditory cortex responses. However, only a few attempts have been made to characterize neural discrimination of communication sounds masked by noise at each stage of the auditory system and to quantify the noise effects on the neuronal discrimination in terms of alterations in amplitude modulations. Here, we measured neural discrimination between communication sounds masked by a vocalization-shaped stationary noise from multiunit responses recorded in the cochlear nucleus, inferior colliculus, auditory thalamus, and primary and secondary auditory cortex at several signal-to-noise ratios (SNRs) in anesthetized male or female guinea pigs. Masking noise decreased sound discrimination of neuronal populations in each auditory structure, but collicular and thalamic populations showed better performance than cortical populations at each SNR. In contrast, in each auditory structure, discrimination by neuronal populations was slightly decreased when tone-vocoded vocalizations were tested. These results shed new light on the specific contributions of subcortical structures to robust sound encoding, and suggest that the distortion of slow amplitude modulation cues conveyed by communication sounds is one of the factors constraining the neuronal discrimination in subcortical and cortical levels.SIGNIFICANCE STATEMENT Dissecting how auditory neurons discriminate communication sounds in noise is a major goal in auditory neuroscience. Robust sound coding in noise is often viewed as a specific property of cortical networks, although this remains to be demonstrated. Here, we tested the discrimination performance of neuronal populations at five levels of the auditory system in response to conspecific vocalizations masked by noise. In each acoustic condition, subcortical neurons better discriminated target vocalizations than cortical ones and in each structure, the reduction in discrimination performance was related to the reduction in slow amplitude modulation cues.


Assuntos
Comunicação Animal , Percepção Auditiva/fisiologia , Discriminação Psicológica/fisiologia , Ruído , Vocalização Animal/fisiologia , Estimulação Acústica , Algoritmos , Animais , Córtex Auditivo/citologia , Córtex Auditivo/fisiologia , Feminino , Cobaias , Masculino , Mascaramento Perceptivo , Razão Sinal-Ruído , Colículos Superiores/citologia , Colículos Superiores/fisiologia , Tálamo/citologia , Tálamo/fisiologia
13.
Proc Natl Acad Sci U S A ; 117(21): 11770-11780, 2020 05 26.
Artigo em Inglês | MEDLINE | ID: mdl-32398367

RESUMO

Despite its ubiquitous use in medicine, and extensive knowledge of its molecular and cellular effects, how anesthesia induces loss of consciousness (LOC) and affects sensory processing remains poorly understood. Specifically, it is unclear whether anesthesia primarily disrupts thalamocortical relay or intercortical signaling. Here we recorded intracranial electroencephalogram (iEEG), local field potentials (LFPs), and single-unit activity in patients during wakefulness and light anesthesia. Propofol infusion was gradually increased while auditory stimuli were presented and patients responded to a target stimulus until they became unresponsive. We found widespread iEEG responses in association cortices during wakefulness, which were attenuated and restricted to auditory regions upon LOC. Neuronal spiking and LFP responses in primary auditory cortex (PAC) persisted after LOC, while responses in higher-order auditory regions were variable, with neuronal spiking largely attenuated. Gamma power induced by word stimuli increased after LOC while its frequency profile slowed, thus differing from local spiking activity. In summary, anesthesia-induced LOC disrupts auditory processing in association cortices while relatively sparing responses in PAC, opening new avenues for future research into mechanisms of LOC and the design of anesthetic monitoring devices.


Assuntos
Anestesia , Córtex Auditivo , Potenciais Evocados Auditivos , Inconsciência/induzido quimicamente , Anestésicos Intravenosos/farmacologia , Córtex Auditivo/efeitos dos fármacos , Córtex Auditivo/fisiologia , Eletrocorticografia , Potenciais Evocados Auditivos/efeitos dos fármacos , Potenciais Evocados Auditivos/fisiologia , Feminino , Humanos , Masculino , Propofol/farmacologia , Vigília/fisiologia
14.
PLoS Biol ; 18(5): e3000674, 2020 05.
Artigo em Inglês | MEDLINE | ID: mdl-32396574

RESUMO

Animals use auditory cues generated by defensive responses of others to detect impending danger. Here we identify a neural circuit in rats involved in the detection of one such auditory cue, the cessation of movement-evoked sound resulting from freezing. This circuit comprises the dorsal subnucleus of the medial geniculate body (MGD) and downstream areas, the ventral area of the auditory cortex (VA), and the lateral amygdala (LA). This study suggests a role for the auditory offset pathway in processing a natural sound cue of threat.


Assuntos
Córtex Auditivo/fisiologia , Percepção Auditiva/fisiologia , Complexo Nuclear Basolateral da Amígdala/fisiologia , Corpos Geniculados/fisiologia , Animais , Aprendizagem da Esquiva/fisiologia , Sinais (Psicologia) , Masculino , Ratos Sprague-Dawley
15.
Neuron ; 107(3): 566-579.e7, 2020 08 05.
Artigo em Inglês | MEDLINE | ID: mdl-32473095

RESUMO

Mother-infant bonding develops rapidly following parturition and is accompanied by changes in sensory perception and behavior. Here, we study how ultrasonic vocalizations (USVs) are represented in the brain of mothers. Using a mouse line that allows temporally controlled genetic access to active neurons, we find that the temporal association cortex (TeA) in mothers exhibits robust USV responses. Rabies tracing from USV-responsive neurons reveals extensive subcortical and cortical inputs into TeA. A particularly dominant cortical source of inputs is the primary auditory cortex (A1), suggesting strong A1-to-TeA connectivity. Chemogenetic silencing of USV-responsive neurons in TeA impairs auditory-driven maternal preference in a pup-retrieval assay. Furthermore, dense extracellular recordings from awake mice reveal changes of both single-neuron and population responses to USVs in TeA, improving discriminability of pup calls in mothers compared with naive females. These data indicate that TeA plays a key role in encoding and perceiving pup cries during motherhood.


Assuntos
Córtex Auditivo/fisiologia , Percepção Auditiva/fisiologia , Comportamento Materno , Plasticidade Neuronal/fisiologia , Neurônios/fisiologia , Lobo Temporal/fisiologia , Vocalização Animal , Animais , Córtex Auditivo/citologia , Fenômenos Eletrofisiológicos , Feminino , Camundongos , Vias Neurais , Apego ao Objeto , Lobo Temporal/citologia , Ondas Ultrassônicas
16.
J Neurosci ; 40(21): 4158-4171, 2020 05 20.
Artigo em Inglês | MEDLINE | ID: mdl-32295815

RESUMO

Vocal production is a sensory-motor process in which auditory self-monitoring is used to ensure accurate communication. During vocal production, the auditory cortex of both humans and animals is suppressed, a phenomenon that plays an important role in self-monitoring and vocal motor control. However, the underlying neural mechanisms of this vocalization-induced suppression are unknown. γ-band oscillations (>25 Hz) have been implicated a variety of cortical functions and are thought to arise from activity of local inhibitory interneurons, but have not been studied during vocal production. We therefore examined γ-band activity in the auditory cortex of vocalizing marmoset monkeys, of either sex, and found that γ responses increased during vocal production. This increase in γ contrasts with simultaneously recorded suppression of single-unit and multiunit responses. Recorded vocal γ oscillations exhibited two separable components: a vocalization-specific nonsynchronized ("induced") response correlating with vocal suppression, and a synchronized ("evoked") response that was also present during passive sound playback. These results provide evidence for the role of cortical γ oscillations during inhibitory processing. Furthermore, the two distinct components of the γ response suggest possible mechanisms for vocalization-induced suppression, and may correspond to the sensory-motor integration of top-down and bottom-up inputs to the auditory cortex during vocal production.SIGNIFICANCE STATEMENT Vocal communication is important to both humans and animals. In order to ensure accurate information transmission, we must monitor our own vocal output. Surprisingly, spiking activity in the auditory cortex is suppressed during vocal production yet maintains sensitivity to the sound of our own voice ("feedback"). The mechanisms of this vocalization-induced suppression are unknown. Here we show that auditory cortical γ oscillations, which reflect interneuron activity, are actually increased during vocal production, the opposite response of that seen in spiking units. We discuss these results with proposed functions of γ activity during inhibitory sensory processing and coordination of different brain regions, suggesting a role in sensory-motor integration.


Assuntos
Córtex Auditivo/fisiologia , Ritmo Gama/fisiologia , Interneurônios/fisiologia , Vocalização Animal/fisiologia , Animais , Callithrix , Eletrodos Implantados , Feminino , Masculino
17.
J Med Life ; 13(1): 102-106, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32341710

RESUMO

Children suffering from conductive or mixed hearing loss may benefit from a bone-anchored hearing aid system (BAHA Attract implantable prosthesis). After audiological rehabilitation, different aspects of development are improving. The objective of this case report is to propose a comprehensive framework for monitoring cortical auditory function after implantation of a bone-anchored hearing aid system by using electrophysiological and neuropsychological measurements. We present the case of a seven-year-old boy with a congenital hearing loss due to a plurimalformative syndrome, including outer and middle ear malformation. After the diagnosis of hearing loss and the audiological rehabilitation with a BAHA Attract implantable prosthesis, the cortical auditory evoked potentials were recorded. We performed a neuropsychological evaluation using the Wechsler Intelligence Scale for Children - Fourth Edition, which was applied according to a standard procedure. The P1 latency was delayed according to the age (an objective biomarker for quantifying cortical auditory function). The neuropsychological evaluation revealed that the child's working memory and verbal reasoning abilities were in the borderline range comparing with his nonverbal reasoning abilities and processing abilities, which were in the average and below-average range, respectively. Cortical auditory evoked potentials, along with neuropsychological evaluation, could be an essential tool for monitoring cortical auditory function in children with hearing loss after a bone-anchored hearing aid implantation.


Assuntos
Córtex Auditivo/fisiologia , Fenômenos Eletrofisiológicos , Auxiliares de Audição , Criança , Orelha Externa/anormalidades , Orelha Externa/fisiopatologia , Potenciais Evocados/fisiologia , Humanos , Anormalidades Maxilomandibulares/fisiopatologia , Masculino , Microstomia/fisiopatologia
18.
J Neurosci ; 40(19): 3783-3798, 2020 05 06.
Artigo em Inglês | MEDLINE | ID: mdl-32273487

RESUMO

Statistical regularities in natural sounds facilitate the perceptual segregation of auditory sources, or streams. Repetition is one cue that drives stream segregation in humans, but the neural basis of this perceptual phenomenon remains unknown. We demonstrated a similar perceptual ability in animals by training ferrets of both sexes to detect a stream of repeating noise samples (foreground) embedded in a stream of random samples (background). During passive listening, we recorded neural activity in primary auditory cortex (A1) and secondary auditory cortex (posterior ectosylvian gyrus, PEG). We used two context-dependent encoding models to test for evidence of streaming of the repeating stimulus. The first was based on average evoked activity per noise sample and the second on the spectro-temporal receptive field. Both approaches tested whether differences in neural responses to repeating versus random stimuli were better modeled by scaling the response to both streams equally (global gain) or by separately scaling the response to the foreground versus background stream (stream-specific gain). Consistent with previous observations of adaptation, we found an overall reduction in global gain when the stimulus began to repeat. However, when we measured stream-specific changes in gain, responses to the foreground were enhanced relative to the background. This enhancement was stronger in PEG than A1. In A1, enhancement was strongest in units with low sparseness (i.e., broad sensory tuning) and with tuning selective for the repeated sample. Enhancement of responses to the foreground relative to the background provides evidence for stream segregation that emerges in A1 and is refined in PEG.SIGNIFICANCE STATEMENT To interact with the world successfully, the brain must parse behaviorally important information from a complex sensory environment. Complex mixtures of sounds often arrive at the ears simultaneously or in close succession, yet they are effortlessly segregated into distinct perceptual sources. This process breaks down in hearing-impaired individuals and speech recognition devices. By identifying the underlying neural mechanisms that facilitate perceptual segregation, we can develop strategies for ameliorating hearing loss and improving speech recognition technology in the presence of background noise. Here, we present evidence to support a hierarchical process, present in primary auditory cortex and refined in secondary auditory cortex, in which sound repetition facilitates segregation.


Assuntos
Córtex Auditivo/fisiologia , Percepção Auditiva/fisiologia , Ruído , Animais , Feminino , Furões , Masculino , Neurônios/fisiologia
19.
J Neurosci ; 40(23): 4469-4482, 2020 06 03.
Artigo em Inglês | MEDLINE | ID: mdl-32327533

RESUMO

Time-dependent frequency trajectories are an inherent feature of many behaviorally relevant sounds, such as species-specific vocalizations. Dynamic frequency trajectories, even in short sounds, often convey meaningful information, which may be used to differentiate sound categories. However, it is not clear what and where neural responses in the auditory cortical pathway are critical for conveying information about behaviorally relevant frequency trajectories, and how these responses change with experience. Here, we uncover tuning to subtle variations in frequency trajectories in auditory cortex of female mice. We found that auditory cortical responses could be modulated by variations in a pure tone trajectory as small as 1/24th of an octave, comparable to what has been reported in primates. In particular, late spiking after the end of a sound stimulus was more often sensitive to the sound's subtle frequency variation compared with spiking during the sound. Such "Off" responses in the adult A2, but not those in core auditory cortex, were plastic in a way that may enhance the representation of a newly acquired, behaviorally relevant sound category. We illustrate this with the maternal mouse paradigm for natural vocalization learning. By using an ethologically inspired paradigm to drive auditory responses in higher-order neurons, our results demonstrate that mouse auditory cortex can track fine frequency changes, which allows A2 Off responses in particular to better respond to pitch trajectories that distinguish behaviorally relevant, natural sound categories.SIGNIFICANCE STATEMENT A whistle's pitch conveys meaning to its listener, as when dogs learn that distinct pitch trajectories whistled by their owner differentiate specific commands. Many species use pitch trajectories in their own vocalizations to distinguish sound categories, such as in human languages, such as Mandarin. How and where auditory neural activity encodes these pitch trajectories as their meaning is learned but not well understood, especially for short-duration sounds. We studied this in mice, where infants use ultrasonic whistles to communicate to adults. We found that late neural firing after a sound ends can be tuned to how the pitch changes in time, and that this response in a secondary auditory cortical field changes with experience to acquire a pitch change's meaning.


Assuntos
Estimulação Acústica/métodos , Potenciais de Ação/fisiologia , Córtex Auditivo/fisiologia , Nível de Percepção Sonora/fisiologia , Tempo de Reação/fisiologia , Fatores Etários , Animais , Eletrodos Implantados , Feminino , Camundongos , Camundongos Endogâmicos CBA , Distribuição Aleatória
20.
PLoS One ; 15(3): e0221541, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32210448

RESUMO

Stimulus-specific adaptation (SSA) is the reduction in responses to a common stimulus that does not generalize, or only partially generalizes, to other stimuli. SSA has been studied mainly with sounds that bear no behavioral meaning. We hypothesized that the acquisition of behavioral meaning by a sound should modify the amount of SSA evoked by that sound. To test this hypothesis, we used fear conditioning in rats, using two word-like stimuli, derived from the English words "danger" and "safety", as well as pure tones. One stimulus (CS+) was associated with a foot shock whereas the other stimulus (CS-) was presented without a concomitant foot shock. We recorded neural responses to the auditory stimuli telemetrically, using chronically implanted multi-electrode arrays in freely moving animals before and after conditioning. Consistent with our hypothesis, SSA changed in a way that depended on the behavioral role of the sound: the contrast between standard and deviant responses remained the same or decreased for CS+ stimuli but increased for CS- stimuli, showing that SSA is shaped by experience. In most cases the sensory responses underlying these changes in SSA increased following conditioning. Unexpectedly, the responses to CS+ word-like stimuli showed a specific, large decrease, which we interpret as evidence for substantial inhibitory plasticity.


Assuntos
Estimulação Acústica/métodos , Adaptação Fisiológica/fisiologia , Percepção Auditiva/fisiologia , Comportamento Animal/fisiologia , Som , Vigília/fisiologia , Animais , Córtex Auditivo/fisiologia , Escala de Avaliação Comportamental , Condicionamento Clássico/fisiologia , Potenciais Evocados Auditivos/fisiologia , Medo/fisiologia , Feminino , Interneurônios/fisiologia , Ratos
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