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1.
J Acoust Soc Am ; 144(4): 2400, 2018 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-30404467

RESUMO

The primary tone phase variation (PTPV) technique combines selective sub-averaging with systematic variation of the phases of multitone stimuli. Each response component having a known phase relationship with the stimulus components phases can be isolated in the time domain. The method was generalized to the frequency-following response (FFR) evoked by a two-tone (f 1 and f 2) stimulus comprising both linear and non-linear, as well as transient components. The generalized PTPV technique isolated each spectral component present in the FFR, including those sharing the same frequency, allowing comparison of their latencies. After isolation of the envelope component f 2 - f 1 from its harmonic distortion 2f 2 - 2f 1 and from the transient auditory brainstem response, a computerized analysis of instantaneous amplitudes and phases was applied in order to objectively determine the onset and offset latencies of the response components. The successive activation of two generators separated by 3.7 ms could be detected in all (N = 12) awake adult normal subjects, but in none (N = 10) of the sleeping/sedated children with normal hearing thresholds. The method offers an unprecedented way of disentangling the various FFR subcomponents. These results open the way for renewed investigations of the FFR components in both human and animal research as well as for clinical applications.

2.
Clin Neurophysiol ; 129(6): 1121-1129, 2018 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-29625343

RESUMO

OBJECTIVES: In patients with Friedreich ataxia (FRDA), mitochondrial failure leads to impaired cellular energetics. Since many FRDA patients have impaired hearing in noise, we investigated the objective consequences on standard auditory brainstem-evoked responses (ABRs). METHODS: In 37 FRDA patients, among whom 34 with abnormal standard ABRs, hearing sensitivity, speech-in-noise intelligibility and otoacoustic emissions were controlled. ABR recordings were split into four consecutive segments of the total time frame used for data collection, thus allowing the dynamics of ABR averaging to be observed. RESULTS: Most ears showed features of an auditory neuropathy spectrum disorder with flattened ABRs and impaired speech-in-noise intelligibility contrasting with near-normal hearing sensitivity and normal preneural responses. Yet split-ABRs revealed short-lived wave patterns in 26 out of 68 ears with flattened standard ABRs (38%). While averaging went on, the pattern of waves shifted so that interwave latencies increased by 35% on average. CONCLUSIONS: In FRDA, the assumption of stationarity used for extracting standard ABRs is invalid. The preservation of early split-ABRs indicates no short-term dyssynchrony of action potentials. A large decrease in conduction velocity along auditory neurons occurs within seconds, attributed to fast energetic failure. SIGNIFICANCE: This model of metabolic sensory neuropathy warns against exposure of metabolically-impaired patients to sustained auditory stimulation.

3.
Dev Sci ; 21(3): e12558, 2018 05.
Artigo em Inglês | MEDLINE | ID: mdl-28256107

RESUMO

Noise typically induces both peripheral and central masking of an auditory target. Whereas the idea that a deficit of speech in noise perception is inherent to dyslexia is still debated, most studies have actually focused on the peripheral contribution to the dyslexics' difficulties of perceiving speech in noise. Here, we investigated the respective contribution of both peripheral and central noise in three groups of children: dyslexic, chronological age matched controls (CA), and reading-level matched controls (RL). In all noise conditions, dyslexics displayed significantly lower performance than CA controls. However, they performed similarly or even better than RL controls. Scrutinizing individual profiles failed to reveal a strong consistency in the speech perception difficulties experienced across all noise conditions, or across noise conditions and reading-related performances. Taken together, our results thus suggest that both peripheral and central interference contribute to the poorer speech in noise perception of dyslexic children, but that this difficulty is not a core deficit inherent to dyslexia.

4.
Neurophysiol Clin ; 48(2): 93-102, 2018 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-29248202

RESUMO

OBJECTIVE: To study the effect of clonidine administrated as a co-analgesic during scoliosis surgery, on the neuromonitoring of spinal motor pathways. METHODS: Using standardized intraoperative monitoring, we compared the time course of peripherally and transcranially electrically evoked motor potentials (TcEMEPs) before and after injection of a single bolus of clonidine in children under total intravenous anesthesia (TIVA). MEP data were obtained from 9 patients and somatosensory evoked potentials (SSEPs) were obtained from 2 patients. The potential effect of clonidine on mean blood pressure (BP) was controlled. RESULTS: TcEMEPs from upper and lower limbs rapidly showed significant drops in amplitude after the injection of clonidine. Amplitudes reached minimal values within five minutes and remained very weak for at least 10-20minutes during which monitoring of the central motor pathways was severely compromised. SSEPs were not altered during maximal amplitude depression of the TcEMEPS. CONCLUSIONS: This is the first report showing that clonidine severely interferes with neuromonitoring of the spinal cord motor pathways. The results are discussed in light of the literature describing the effects of dexmedetomidine, another α-2 adrenergic agonist. The experimental and literature data point to central mechanisms taking place at both the spinal and cerebral levels. Therefore, clonidine as well as other α-2 adrenergic agonists should be used with extreme caution in patients for whom neuromonitoring of the motor pathways is required during surgery.


Assuntos
Clonidina/uso terapêutico , Potencial Evocado Motor/efeitos dos fármacos , Potenciais Somatossensoriais Evocados/efeitos dos fármacos , Monitorização Intraoperatória , Escoliose/cirurgia , Adolescente , Criança , Clonidina/administração & dosagem , Potencial Evocado Motor/fisiologia , Potenciais Somatossensoriais Evocados/fisiologia , Feminino , Humanos , Masculino , Monitorização Intraoperatória/métodos , Estudos Retrospectivos , Escoliose/tratamento farmacológico
5.
Neuroreport ; 29(1): 48-53, 2018 Jan 03.
Artigo em Inglês | MEDLINE | ID: mdl-29189635

RESUMO

Recent research found that configural information is less important for the processing of sexualized bodies than for the processing of nonsexualized bodies. The present investigation aims to expand these findings by directly manipulating configural versus analytic processing of sexualized and nonsexualized bodies. We posited that disrupting first-order relational information through scrambling should be associated with larger N170 amplitudes (scrambling effect) for nonsexualized bodies, whereas the scrambling manipulation should not modulate N170 amplitudes associated with sexualized bodies and objects. We presented images of scrambled versus intact sexualized bodies, nonsexualized bodies, and objects while the N170 was recorded. Consistent with our hypothesis, we found that the scrambling manipulation was associated with larger N170 amplitudes for nonsexualized bodies (i.e. scrambling effect), whereas no scrambling effect emerged for sexualized bodies and objects. This research is the first to show that sexualized bodies are processed analytically at a neural level. Implications for the literature in body perception and objectification will be discussed.


Assuntos
Mapeamento Encefálico , Encéfalo/fisiologia , Potenciais Evocados/fisiologia , Reconhecimento Visual de Modelos/fisiologia , Caracteres Sexuais , Adulto , Análise de Variância , Eletroencefalografia , Feminino , Humanos , Masculino , Estimulação Luminosa , Tempo de Reação , Estatística como Assunto , Adulto Jovem
6.
Behav Brain Funct ; 12(1): 11, 2016 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-26979812

RESUMO

BACKGROUND: Optimal stimulation theory and moderate brain arousal (MBA) model hypothesize that extra-task stimulation (e.g. white noise) could improve cognitive functions of children with attention-deficit/hyperactivity disorder (ADHD). We investigate benefits of white noise on attention and inhibition in children with and without ADHD (7-12 years old), both at behavioral and at neurophysiological levels. METHODS: Thirty children with and without ADHD performed a visual cued Go/Nogo task in two conditions (white noise or no-noise exposure), in which behavioral and P300 (mean amplitudes) data were analyzed. Spontaneous eye-blink rates were also recorded and participants went through neuropsychological assessment. Two separate analyses were conducted with each child separately assigned into two groups (1) ADHD or typically developing children (TDC), and (2) noise beneficiaries or non-beneficiaries according to the observed performance during the experiment. This latest categorization, based on a new index we called "Noise Benefits Index" (NBI), was proposed to determine a neuropsychological profile positively sensitive to noise. RESULTS: Noise exposure reduced omission rate in children with ADHD, who were no longer different from TDC. Eye-blink rate was higher in children with ADHD but was not modulated by white noise. NBI indicated a significant relationship between ADHD and noise benefit. Strong correlations were observed between noise benefit and neuropsychological weaknesses in vigilance and inhibition. Participants who benefited from noise had an increased Go P300 in the noise condition. CONCLUSION: The improvement of children with ADHD with white noise supports both optimal stimulation theory and MBA model. However, eye-blink rate results question the dopaminergic hypothesis in the latter. The NBI evidenced a profile positively sensitive to noise, related with ADHD, and associated with weaker cognitive control.


Assuntos
Estimulação Acústica/métodos , Transtorno do Deficit de Atenção com Hiperatividade/psicologia , Transtorno do Deficit de Atenção com Hiperatividade/terapia , Cognição/fisiologia , Ruído , Atenção/fisiologia , Transtorno do Deficit de Atenção com Hiperatividade/fisiopatologia , Criança , Sinais (Psicologia) , Eletroencefalografia , Potenciais Evocados Auditivos , Feminino , Humanos , Masculino , Desempenho Psicomotor/fisiologia
7.
Med Hypotheses ; 86: 14-7, 2016 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-26804591

RESUMO

Recent studies reported over-expression of a cytokine (Interleukin (IL)-18) in the serum of sporadic amyotrophic lateral sclerosis (sALS) patients. Here, we report on the first-time detection of in-situ expression of activated IL-18 in the human brain in sALS patients. We also detected cerebral in-situ expression of key-molecules known to be closely related to the molecular network associated with the activation/secretion of IL-18 cytokine, namely, the receptor-interacting serine/threonine-protein kinase 3 (RIPK3 or RIP3), NOD-like receptor pyrin domain containing 3 (NLRP3)-inflammasome, and activated caspase-1. These findings suggest and allow to hypothesize that there might be a role for this cytokine network in molecular mechanisms associated with or implicated in the physiopathology of this neurodegenerative disorder.


Assuntos
Esclerose Amiotrófica Lateral/imunologia , Encéfalo/imunologia , Encefalite/imunologia , Mediadores da Inflamação/imunologia , Interleucina-18/imunologia , Modelos Imunológicos , Humanos , Imunidade Inata/imunologia , Modelos Neurológicos
8.
J Acoust Soc Am ; 137(6): EL496-502, 2015 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-26093461

RESUMO

Studies evaluating speech perception in noise have reported inconsistent results regarding a potential deficit in dyslexic children. So far, most of them investigated energetic masking. The present study evaluated situations inducing mostly informational masking, which reflects cognitive interference induced by the masker. Dyslexic children were asked to identify a female target syllable presented in quiet, babble, unmodulated, and modulated speech-shaped noise. Whereas their performance was comparable to normal-reading children in quiet, it dropped significantly in all noisy conditions compared to age-, but not reading level-matched controls. Interestingly, noise affected similarly the reception of voicing, place, and manner of articulation in dyslexic and normal-reading children.


Assuntos
Comportamento Infantil , Dislexia/psicologia , Ruído/efeitos adversos , Mascaramento Perceptivo , Percepção da Fala , Estimulação Acústica , Fatores Etários , Estudos de Casos e Controles , Criança , Sinais (Psicologia) , Dislexia/diagnóstico , Feminino , Humanos , Alfabetização , Masculino , Fonética , Recognição (Psicologia)
9.
Radiology ; 275(2): 530-7, 2015 May.
Artigo em Inglês | MEDLINE | ID: mdl-25575119

RESUMO

PURPOSE: To evaluate the effects of exposure to routine magnetic resonance (MR) imaging at 1.5 T during pregnancy on fetal growth and neonatal hearing function in relation to the dose and timing of in utero exposure in a group of newborns at low risk for congenital hearing impairment or deafness. MATERIALS AND METHODS: This retrospective case-control study was approved by the local ethics committee, and written informed consent was waived. Between January 2008 and December 2012, a group of 751 neonates exposed to MR imaging in utero and a group of control subjects comprising 10 042 nonexposed neonates, both groups with no risk factors for hearing impairment at birth, were included. Neonatal hearing screening was performed by means of otoacoustic emission testing and auditory brain stem response according to national guidelines, and the prevalence of hearing impairment in the two groups was compared by using a noninferiority test with Wilson score confidence intervals. The effect of MR exposure on birth weight percentile was examined between the singleton neonates in the exposed group and a randomly chosen subset of 1805 singleton newborns of the nonexposed group by performing an analysis of variance. RESULTS: The rate of hearing impairment or deafness was found to be 0% (0 of 751) in the neonates in the exposed group and was not inferior to that in the nonexposed group (34 of 10 042 [0.34%], P < .05). There was no between-group difference in birth weight percentiles (50.6% for exposed vs 48.4% for nonexposed; P = .22). CONCLUSION: This study showed no adverse effects of exposure to 1.5-T MR imaging in utero on neonatal hearing function or birth weight percentiles.


Assuntos
Peso ao Nascer/efeitos da radiação , Feto/efeitos da radiação , Audição/efeitos da radiação , Imagem por Ressonância Magnética/efeitos adversos , Ruído/efeitos adversos , Estudos de Casos e Controles , Feminino , Idade Gestacional , Humanos , Recém-Nascido , Imagem por Ressonância Magnética/métodos , Masculino , Gravidez , Doses de Radiação , Estudos Retrospectivos
10.
Ear Hear ; 36(3): 330-7, 2015 May-Jun.
Artigo em Inglês | MEDLINE | ID: mdl-25401380

RESUMO

OBJECTIVES: Interference between a target and simultaneous maskers occurs both at the cochlear level through energetic masking and more centrally through informational masking (IM). Hence, quantifying the amount of IM requires a strict control of the energetic component. Presenting target and maskers on different sides (i.e., dichotically) reduces energetic masking but provides listeners with important lateralization cues that also drastically reduce IM. The main purpose of this study (Experiment 1) was to evaluate a "switch" manipulation aiming at restoring most of the IM despite dichotic listening. Experiment 2 was designed to investigate the source of the difficulty induced by this switching dichotic condition. DESIGN: In Experiment 1, the authors presented 60 normal-hearing young adults with a detection task in which a regularly repeating target was embedded in a randomly varying background masker. The authors evaluated spatial masking release induced by three different dichotic listening conditions in comparison with a diotic baseline. Dichotic stimuli were presented in either a nonswitching or a switching condition. In the latter case, the presentation sides of dichotic target and maskers alternated several times throughout 10 sec sequences. The impact of the number of switches on IM was investigated parametrically, with both pure and complex tone sequences. In Experiment 2, the authors compared performance of 13 young, normal-hearing listeners in a monotic and dichotic version of the rapidly switching condition, using pure-tone sequences. RESULTS: When target and maskers switched rapidly within sequences, IM was significantly stronger than in nonswitching dichotic sequences and was comparable with the masking effect induced by diotic sequences. Furthermore, Experiment 2 suggests that rapidly switching target and maskers prevent listeners from relying on lateralization cues inherent to the dichotic condition, hence preserving important amounts of IM. CONCLUSIONS: This paradigm thus provides an original tool to isolate IM in signal and maskers having overlapping spectra.


Assuntos
Percepção Auditiva/fisiologia , Mascaramento Perceptivo/fisiologia , Estimulação Acústica/métodos , Adolescente , Adulto , Audiometria , Audiometria de Tons Puros , Testes com Listas de Dissílabos/métodos , Feminino , Humanos , Masculino , Adulto Jovem
11.
Neurosci Lett ; 584: 71-6, 2015 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-25459281

RESUMO

In complex auditory scenes, perceiving a given target signal is often complicated by the presence of competing maskers. In addition to energetic masking (EM), which arises because of peripheral interferences between target and maskers at the cochlear level, informational masking (IM), which takes place at a more central level, is also responsible for the difficulties encountered in typical ecological auditory environments. While recent research has led to mixed results regarding a potential speech-perception-in-noise deficit in dyslexic children, most of them actually investigated EM situations. The current study aimed at evaluating dyslexic children's sensitivity to pure IM in complex auditory sequences. Performance of the control normally-reading children increased throughout the experiment, reaching a significantly better level than dyslexics' in the last blocks. Our results provide evidence for a general auditory deficit in noise in dyslexic children. Although due to central mechanisms, this deficit does not seem to stem from a mere auditory attention impairment. Further research is needed to examine the precise nature of the auditory difficulty, and its link with reading acquisition in dyslexic children.


Assuntos
Percepção Auditiva , Dislexia/psicologia , Mascaramento Perceptivo , Estimulação Acústica , Atenção , Criança , Humanos , Psicoacústica
12.
Handb Clin Neurol ; 113: 1527-38, 2013.
Artigo em Inglês | MEDLINE | ID: mdl-23622376

RESUMO

With prevalence figures close to 0.2% at birth and rising to 0.35% during adolescence, hearing loss is the most frequent sensory impairment in childhood. This silent handicap has to be actively sought for without delay as it will seriously interfere with the development of speech, language, cognitive and socio-emotional behavior. Objective physiological techniques (evoked potentials, oto-acoustic emissions, tympanometry) combined according to the cross-check principle allow early diagnosis. Objective testing yields invaluable information about the mechanism of the loss and the contribution of disruption of the neural code to the handicap. Among the acquired causes, cytomegalovirus (CMV) infections plays a major role and may take elusive forms. Aminoglycoside ototoxicity has a genetic determinant. Meningitis can lead to rapid endocochlear ossification prompting for rapid cochlear implantation. Genetic causes account for more than 60% of congenital hearing loss, new genetic causes being discovered at an amazing rate. The high number of genetic entities and their huge heterogeneity among them requires guidelines for requesting genetic testing when desirable. Several syndromes prone to request neuropediatricians' attention as an early diagnosis followed by specific treatment can considerably limit the ensuing handicap. Whatever the type of assistive device fitted (amplifying hearing aid or cochlear implant) and the importance of associated handicaps, a multidisciplinary rehabilitation combined with educated parental commitment is necessary for optimal results.


Assuntos
Perda Auditiva/diagnóstico , Perda Auditiva/etiologia , Perda Auditiva/reabilitação , Audiometria , Criança , Implante Coclear , Implantes Cocleares , Potenciais Evocados Auditivos/fisiologia , Perda Auditiva/epidemiologia , Humanos , Prevalência , Índice de Gravidade de Doença
13.
Med Hypotheses ; 78(6): 793-5, 2012 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-22498047

RESUMO

Cytokines interact with neurotransmitters and modify neuronal and neuroimmune functions. Intense in situ neuronal IL-2 immunoreactivity was detected in vital human brainstem neuronal centers which are principally implicated in cardio-respiratory control mechanisms. These observations were made in critically-ill aging adult as well as in young infant patients dying from various clinico-pathological conditions. We suggested that this in situ cytokine over-expression might tip a delicate balance in molecular interactions in those vital neuro-vegetative centers, causing disturbed homeostatic control of cardio-respiratory functions and impaired arousal responses; we further hypothesized that this IL-2-induced neuro-molecular disequilibrium in the brainstem microenvironment might thus be part of a final common pathway leading to death.


Assuntos
Vias Autônomas/fisiologia , Tronco Encefálico/metabolismo , Morte , Interleucina-2/metabolismo , Modelos Biológicos , Neurônios/metabolismo , Respiração , Tronco Encefálico/citologia , Humanos , Neurotransmissores/metabolismo
14.
Neurosci Lett ; 480(2): 122-6, 2010 Aug 16.
Artigo em Inglês | MEDLINE | ID: mdl-20542085

RESUMO

Dysfunction in vital brainstem centers, including those controlling cardiorespiratory- and sleep/arousal pathophysiology, is reported in sudden infant death syndrome (SIDS). Biological mechanisms underlying SIDS, however, remain unclear. Cytokines are inter-cellular signaling chemicals. They can interact with neurotransmitters and might thus modify neural and neuroimmune functions. Cytokines could therefore act as neuromodulators. Interleukin (IL)-2 is a major immune-related cytokine. It has not been previously depicted in vital brainstem centers. We detected intense neuronal IL-2 immune-reactivity in the SIDS brainstem, namely in vital neural centers. This IL-2 overexpression might interfere with neurotransmitters in those critical brainstem centers, causing disturbed homeostatic control of cardiorespiratory and arousal responses, possibly leading to SIDS.


Assuntos
Tronco Encefálico/metabolismo , Interleucina-2/metabolismo , Neuroimunomodulação , Morte Súbita do Lactente/imunologia , Tronco Encefálico/patologia , Feminino , Humanos , Lactente , Masculino , Morte Súbita do Lactente/patologia
15.
Int J Audiol ; 49(6): 455-62, 2010 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-20482293

RESUMO

Auditory steady-state evoked potential (ASSEP) tuning curves were compared to compound action potential (CAP) tuning curves, both measured at 2 Hz, using sedated beagle puppies. The effect of two types of masker (narrowband noise and sinusoidal) on the tuning curve parameters was assessed. Whatever the masker type, CAP tuning curve parameters were qualitatively and quantitatively similar to the ASSEP ones, with a similar inter-subject variability, but with a greater incidence of upward tip displacement. Whatever the procedure, sinusoidal maskers produced sharper tuning curves than narrow-band maskers. Although these differences are not likely to have significant implications for clinical work, from a fundamental point of view, their origin requires further investigations. The same amount of time was needed to record a CAP and an ASSEP 13-point tuning curve. The data further validate the ASSEP technique, which has the advantages of having a smaller tendency to produce upward tip shifts than the CAP technique. Moreover, being non invasive, ASSEP tuning curves can be easily repeated over time in the same subject for clinical and research purposes.


Assuntos
Potenciais de Ação/fisiologia , Limiar Auditivo/fisiologia , Nervo Coclear/fisiologia , Potenciais Evocados Auditivos/fisiologia , Mascaramento Perceptivo/fisiologia , Nível de Percepção Sonora/fisiologia , Espectrografia do Som , Estimulação Acústica , Fatores Etários , Algoritmos , Animais , Cães , Eletroencefalografia , Feminino , Masculino , Psicoacústica , Processamento de Sinais Assistido por Computador , Software , Especificidade da Espécie
16.
J Exp Child Psychol ; 104(4): 353-66, 2009 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-19709671

RESUMO

By examining voice onset time (VOT) discrimination in 4- and 8-month-olds raised in a French-speaking environment, the current study addresses the question of the role played by linguistic experience in the reshaping of the initial perceptual abilities. Results showed that the language-general -30- and +30-ms VOT boundaries are better discriminated than the 0-ms boundary in 4-month-olds, whereas 8-month-olds better discriminate the 0-ms boundary. These data support explanations of speech development stressing the effects of both language-general boundaries and linguistic environment (attunement theory and coupling theory). Results also suggest that the acquisition of the adult voicing boundary (at 0 ms VOT in French vs. +30 ms VOT in English) is faster and more linear in French than in English. This latter aspect of the results might be related to differences in the consistency of VOT distributions of voiced and voiceless stops between languages.


Assuntos
Desenvolvimento da Linguagem , Fala , Voz , Feminino , França , Humanos , Lactente , Masculino , Percepção da Fala
17.
Int J Audiol ; 48(2): 55-62, 2009 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-19219689

RESUMO

The effect of the level of threshold equalizing noise (TEN) on the diagnosis of dead regions (DRs) was investigated. Participants comprised 23 adults with sensorineural hearing impairment. Masked thresholds were measured monaurally with TEN at 60, 70, 80, and 90 dB HL/ERB(N). Absolute and masked thresholds (with TEN at 80 dB HL/ERB(N)) were retested. The diagnosis was unaffected by TEN level at any frequency for eight of the 13 participants who met the criteria for a DR. For four of the latter, increasing the TEN level changed the diagnosis from DR to no DR, mainly at 1.5 kHz, corresponding to the edge frequency, f(e), of the DR. For one participant with a low-frequency DR, increasing the TEN level changed the diagnosis from no DR to DR, only at 1 kHz. The changes with level were too large to be explained in terms of test repeatability. Overall, the results of the TEN test are usually not affected by TEN level, except for test frequencies close to f(e) when absolute thresholds are near-normal for frequencies adjacent to f(e).


Assuntos
Audiometria de Tons Puros/métodos , Limiar Auditivo , Perda Auditiva Neurossensorial/diagnóstico , Psicoacústica , Adulto , Idoso , Idoso de 80 Anos ou mais , Células Ciliadas Auditivas Internas/patologia , Humanos , Pessoa de Meia-Idade , Reprodutibilidade dos Testes
18.
Ear Hear ; 30(1): 43-53, 2009 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-19125026

RESUMO

OBJECTIVES: Assess the feasibility of drawing tuning curves from the masking function of steady state potentials. Develop a noninvasive tool for research applications on cochlear frequency selectivity in sedated animals. Obtain pilot human data validating auditory steady state evoked potential-derived (ASSEP) tuning curves against psychophysical data. DESIGN: ASSEP tuning curves were drawn in 10 Beagle puppies and six human adults using amplitude-modulated probes. Two probe frequencies (1 and 2 kHz) were used in dogs and only one (2 kHz) in humans. The modulation rates of the two probes were set to 81 and 88 Hz, respectively. Psychophysical tuning curves were obtained in 12 normal human subjects using the same maskers and either a pure-tone or an amplitude-modulated probe to verify if the latter had a specific effect on tuning curve parameters. Six of these 12 subjects participated in the electrophysiologic measurements. For each tuning curve, the intensity of the narrowband masker required just to mask the fixed probe was plotted for different masker center frequencies. Masker center frequencies extended to about half an octave above and an octave below the probe frequencies in 100-Hz steps. Tuning curve width (Q10 dB values), high- and low-frequency slopes (in dB/octave) and the masker frequency yielding the lowest masking threshold (maximal masker frequency) were computed. Canine Q10 dB values obtained were compared with those published for several species with other techniques. For humans, ASSEP and psychophysical tuning curves were directly compared in the same subjects and with published data. RESULTS: In dogs, the ASSEP method yielded reproducible tuning curves with qualitative and quantitative parameters similar to other physiologic measures of tuning obtained in various animals. Q10 dB values were greater at 2 than at 1 kHz, reflecting the well-known correlation between sharpness of tuning and central frequency. In humans, ASSEP Q10 dB values were slightly smaller than the psychophysical ones, but were greater by a factor of 2 than those obtained with previously published electrophysiologic procedures. In both species, detuning-a shift of the tip of the curve away from the probe frequency-was frequently observed as upward shifts with a maximal value of 200 Hz. Human psychophysical tuning curves also showed a certain amount of upward detuning. The intraindividual comparison of the two types of probes performed on human subjects with the psychophysical method did not indicate a specific effect of the amplitude-modulated probe on the curve parameters. Neither did the intraindividual comparisons indicate that an amplitude-modulated probe per se promoted detuning. Detuning has been observed with several other techniques and is usually attributed to nonlinear interactions between masker and probe in simultaneous masking. CONCLUSIONS: The results demonstrate the feasibility of measuring realistic ASSEP tuning curves in sedated dogs and in sleeping human adults. The ASSEP tuning curves exhibit a series of classical features similar to those obtained with time-honored methods. These results pave the way for the development of a noninvasive electrophysiologic method for tuning curve recording and its applications in noncooperative experimental animals or clinical subjects.


Assuntos
Cóclea/fisiologia , Potenciais Evocados Auditivos , Homeostase , Adulto , Animais , Cães , Estudos de Viabilidade , Feminino , Humanos , Hipnóticos e Sedativos , Masculino , Mascaramento Perceptivo , Projetos Piloto , Psicofísica , Reprodutibilidade dos Testes , Sono/fisiologia , Adulto Jovem
19.
Clin Neurophysiol ; 117(8): 1760-71, 2006 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-16798083

RESUMO

OBJECTIVE: To define the optimal stimulation parameters (AM/FM vs AM alone and modulation rate) for frequency-specific threshold measurements using ASSEPs in dogs. Dependent variables were thresholds and recording times needed to obtain a response at threshold. To compare the ASSEP threshold results obtained with the optimal stimulation parameters to those obtained with the Tone-Burst/Auditory Brainstem Response (TB/ABR) combination. METHODS: Thirty-two sedated Beagle puppies were tested at 5 audiometric frequencies (0.5-8 kHz) and 6 ASSEP modulation rates (21-199 Hz). RESULTS: The ASSEP threshold-modulation rate functions had a high-pass profile with corner frequencies of 101 Hz for 0.5, 1 and 2 kHz carriers and of 151 Hz for 4 and 8 kHz carriers. AM stimuli did not yield higher thresholds than the AM/FM ones except at 1 kHz. Modulation type had no effect on testing duration. Audiometric profiles were obtained much more rapidly with ASSEPs than with TB/ABRs (mean: 50 vs 135 min). Both ASSEP and TB/ABR provided thresholds estimates characterized by low intersubject variability. CONCLUSIONS: ASSEPs are a valid and rapid method for audiometric assessment in sedated dogs. SIGNIFICANCE: ASSEPs offer a new, competitive tool for frequency-specific assessment of hearing in the canine species.


Assuntos
Estimulação Acústica , Audiometria de Resposta Evocada , Limiar Auditivo/fisiologia , Tronco Encefálico/fisiologia , Potenciais Evocados Auditivos do Tronco Encefálico/fisiologia , Animais , Audiometria de Resposta Evocada/métodos , Cães , Feminino , Masculino
20.
Pediatr Neurol ; 28(3): 178-83, 2003 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-12770669

RESUMO

Assessment of prognosis of children in hypoxic coma is difficult. The value of clinical evaluation is often limited. The usefulness of electrophysiologic tests has been documented mostly in adults and neonates and in cases of traumatic coma. We reviewed retrospectively 39 consecutive children with nontraumatic hypoxic coma to assess the prognostic value of EEG, visual, and auditory evoked potentials. Correlation between electrophysiology and neurologic outcome after mean follow-up period of 30 months was significant (r(s) = 0.6, P < 0.001). In contrast there was no correlation between Pediatric Risk of Mortality score (PRISM) and outcome (r(s) = -0.42, P = 0.8). Combining magnetic resonance imaging with electrophysiology further enhanced their prognostic value (r(s) = 0.69, P < 0.001). Neuroimaging was highly sensitive but less specific, and electrophysiologic tests were highly specific but less sensitive. We conclude that early electrophysiology can contribute to predicting outcome in pediatric hypoxic coma.


Assuntos
Coma/diagnóstico , Hipóxia Encefálica/diagnóstico , Adolescente , Criança , Pré-Escolar , Coma/fisiopatologia , Eletroencefalografia/métodos , Eletrofisiologia , Potenciais Evocados Auditivos/fisiologia , Potenciais Evocados Visuais/fisiologia , Feminino , Humanos , Hipóxia Encefálica/fisiopatologia , Lactente , Imagem por Ressonância Magnética/métodos , Masculino , Valor Preditivo dos Testes , Estudos Retrospectivos , Estatísticas não Paramétricas
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