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1.
Resusc Plus ; 11: 100272, 2022 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-35832320

RESUMEN

We describe a case of new onset movement disorder in a patient with ventricular tachycardia storm supported with peripheral VA ECMO. The differential diagnosis of abnormal movements in a post cardiac arrest patient requiring temporary mechanical circulatory support for cardiogenic shock is explored.

2.
J Vasc Surg Venous Lymphat Disord ; 9(3): 621-626, 2021 05.
Artículo en Inglés | MEDLINE | ID: mdl-32858244

RESUMEN

OBJECTIVE: Catheter-directed interventions (CDIs) have been increasingly used for selected patients with acute intermediate-risk (submassive) pulmonary embolism (sPE) to prevent decompensation, mortality, and potentially long-term sequelae. The purpose of the present study was to determine whether the choice of anesthetic during these interventions has an effect on the postprocedural outcomes. METHODS: Patients who had undergone CDI for acute sPE from 2009 to 2019 were identified and grouped according to the intraprocedural use of propofol. The primary outcome was in-hospital intra- or postprocedural major adverse events, defined as the need for intubation, progression to massive pulmonary embolism, and in-hospital death. Major bleeding events (ie, intracerebral hemorrhage, transfusion of ≥2 U, the need for reintervention) were also assessed. Multivariate logistic regression analysis was used to evaluate the predictors of the studied outcomes. RESULTS: During the study period, 340 patients (age, 58.74 ± 15.22 years; 51.2% men) had undergone CDI for sPE (85 standard thrombolysis, 229 ultrasound-assisted thrombolysis, 26 suction thrombectomy). Propofol had been used for 36 patients (10.6%); the remaining 304 patients (89.4%) had received midazolam plus fentanyl, morphine, or hydromorphone for anesthesia. The baseline characteristics of both groups were similar, except for age, hypertension, American Society of Anesthesiologists class, and procedure type, with ultrasound-assisted thrombolysis the predominant procedure for the no-propofol group (74%). Overall, 18 patients had experienced ≥1 events of the composite outcome (ie, 10 intubations, 11 decompensations, 2 surgical conversions, 3 deaths). The propofol group had a significantly greater adverse event rate (13.8%; n = 5) compared with the no-propofol group (4.2%; n = 13; P = .015). On multivariate analysis, propofol was still a predictive factor for adverse events (odds ratio, 3.79; 95% confidence interval, 1.11-12.93; P = .03). A total of 16 patients had experienced major bleeding or other procedure-related events, including stroke in 4 (1.17%), coronary sinus perforation in 1, tricuspid valve rupture in 1, and the need for transfusion in 10 patients. The type of intervention (ie, standard thrombolysis, ultrasound-assisted thrombolysis, suction thrombectomy) was not a predictive factor for any studied outcome. CONCLUSIONS: CDIs are low-risk procedures with minimal postoperative morbidity and mortality in the setting of acute sPE. However, the use of propofol for intraprocedural sedation should be avoided because it can have detrimental effects.


Asunto(s)
Anestésicos Intravenosos/efectos adversos , Propofol/efectos adversos , Embolia Pulmonar/terapia , Trombectomía/efectos adversos , Terapia Trombolítica/efectos adversos , Adulto , Anciano , Anestésicos Intravenosos/administración & dosificación , Femenino , Humanos , Masculino , Persona de Mediana Edad , Propofol/administración & dosificación , Embolia Pulmonar/diagnóstico por imagen , Embolia Pulmonar/mortalidad , Estudios Retrospectivos , Medición de Riesgo , Factores de Riesgo , Trombectomía/mortalidad , Terapia Trombolítica/mortalidad , Factores de Tiempo , Resultado del Tratamiento
4.
J Acoust Soc Am ; 136(6): EL424, 2014 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-25480093

RESUMEN

Selective adaptation studies in dichotic sound lateralization have contributed to a three-channel model of lateralization mechanisms. They usually have employed highly-lateralized adaptor stimuli, and the expression of the selective adaptation is the perceptual shift of test tone locations away from that of the adaptor. The present study employed modestly lateralized adaptors so that any repulsion mechanism could be visualized in distorted position judgments for test tones on both sides of the adaptor stimuli. Comparison of position reports for tones lateralized using interaural time differences before and after selective adaptation provided no evidence for a repulsion effect.

5.
Crit Care ; 17(3): 319, 2013 May 29.
Artículo en Inglés | MEDLINE | ID: mdl-23731998

RESUMEN

CITATION: Myburgh JA, Finfer S, Bellomo R, Billot L, Cass A, Gattas D, Glass P, Lipman J, Liu B, McArthur C, McGuinness S, Rajbhandari D, Taylor CB, Webb SA; CHEST Investigators; Australian and New Zealand Intensive Care Society Clinical Trials Group: Hydroxyethyl starch or saline for fluid resuscitation in intensive care. N Engl J Med 2012, 367:1901-1911. BACKGROUND: The safety and efficacy of hydroxyethyl starch (HES) for fluid resuscitation have not been fully evaluated, and adverse effects of HES on survival and renal function have been reported. METHODS: We randomly assigned 7,000 patients who had been admitted to an intensive care unit (ICU) in a 1:1 ratio to receive either 6% HES with a molecular weight of 130 kDa and a molar substitution ratio of 0.4 (130/0.4, Voluven; Fresenius Kabi AG, Bad Homburg vor der Höhe, Germany) in 0.9% sodium chloride or 0.9% sodium chloride (saline) for all fluid resuscitation until ICU discharge, death, or 90 days after randomization. The primary outcome was death within 90 days. Secondary outcomes included acute kidney injury and failure and treatment with renal replacement therapy. OBJECTIVE: We conducted a large-scale randomized controlled trial to evaluate the safety and efficacy of 6% HES(130/0.4) in 0.9% saline as compared with 0.9% saline alone for fluid resuscitation in a heterogeneous population of adult patients in the ICU. DESIGN: The Crystalloid versus Hydroxyethyl Starch Trial (CHEST) was an investigator-initiated, multicenter,prospective, blinded, parallel-group, randomized controlled trial. SETTING: The study was set at 32 hospitals in Australia and New Zealand. SUBJECTS: The subjects were adult patients (>18 years) who were admitted to the ICU and who required intravenous fluid above maintenance requirements determined by the treating clinician and supported by at least one objective physiological criterion. Patients were excluded if they received more than 1 L of 6% HES within 24 hours of screening or had one of the following:dialysis-dependent or impending dialysis renal failure,computed tomography evidence of non-traumatic intracranial hemorrhage (ICH) or severe traumatic ICH, creatinine of more than 3.9 mg/dL or urine output of less than 10 mL/hour for 12 hours, sodium of more than 160 meq/L, or chloride of more than 130 meq/L. Also excluded were females of childbearing age (unless proven not to be pregnant) and patients who had post-cardiac surgery status, liver transplant, or burns and those whose death was judged to be imminent or whose underlying disease process indicated a life expectancy of less than 90 days. INTERVENTION: If fluid was deemed necessary by the treating clinician by the parameters described above, the patient received 'study' fluid with identical packaging and appearance. The fluid was either 6% HES (130/0.4) in saline (Voluven) or 0.9% saline. OUTCOMES: Th e primary outcome was death within 90 days. Secondary outcomes were acute kidney injury (AKI) and failure and treatment with renal replacement therapy. RESULTS: A total of 597 (18.0%) of 3,315 patients in the HES group and 566 (17.0%) of 3,336 in the saline group died (relative risk (RR) in the HES group 1.06, 95% confidence interval (CI) 0.96 to 1.18; P=0.26). There was no significant difference in mortality in six predefined subgroups. AKI--defined by RIFLE (Risk, Injury, Failure, Loss, and End-stage kidney disease) criteria--occurred in few patients receiving HES (34.6%) compared with saline (38%) (RR 0.91, 95% CI 0.85 to 0.97). However, renal replacement therapy was used in 235 (7.0%) of 3,352 patients in the HES group and 196 (5.8%) of 3,375 in the saline group (RR 1.21, 95% CI 1.00 to 1.45; P=0.04). HES was significantly associated with more adverse events (5.3% versus 2.8%; P<0.001). CONCLUSIONS: In patients in the ICU, there was no significant difference in 90-day mortality between patients resuscitated with 6% HES (130/0.4) or saline. However, despite a lower overall rate of AKI, more patients who received resuscitation with HES were given renal replacement therapy. (The study was supported by the National Health and Medical Research Council of Australia; the Ministry of Health, New South Wales Government, Australia; and Fresenius Kabi; and by a Practitioner Fellowship from the National Health and Medical Research Council of Australia (to Drs Myburgh and Bellomo), by a Principal Research Fellowship from the National Health and Medical Research Council of Australia (to Dr Cass), and by a Practitioner Fellowship from the Medical Research Foundation of the Royal Perth Hospital (to Dr Webb); CHEST ClinicalTrials.gov number NCT00935168.).


Asunto(s)
Enfermedad Crítica/terapia , Fluidoterapia/métodos , Derivados de Hidroxietil Almidón/uso terapéutico , Femenino , Humanos , Masculino
6.
Ear Hear ; 34(4): e38-51, 2013.
Artículo en Inglés | MEDLINE | ID: mdl-23403808

RESUMEN

OBJECTIVE: The objective of this study was to examine the role of the acoustic stapedius reflex in the protection of speech recognition from the upward spread of masking arising from low-frequency background noise. DESIGN: Speech recognition scores were measured for nine control participants (19-34 years) and six patients with transected stapedius tendons poststapedotomy (39-57 years) as a function of the amplitude of a low-frequency masker, presented at nominal signal to noise ratios of +5 dB, -5 dB, and -15 dB. All participants had pure-tone hearing thresholds in the normal range. Continuous high-pass noise was present in all conditions to avoid ceiling effects; this reduced performance in quiet to approximately 85% for all participants. Scores were measured for soft and loud nonsense syllables (average third octave band levels of 35 and 65 dB SPL), so that a comparison of the low-frequency noise masking functions at the two levels would provide information about the effects of the reflex on speech intelligibility in noise. A third group of nine control participants (19-22 years) listened in the presence of a low-frequency masker gated to come on 1 sec before stimulus onset, to reduce the likelihood of reflex adaptation. The Speech-Intelligibility Index was used to quantify the amount of speech information available in each condition. RESULTS: Patients with transected tendons performed more poorly than control participants as a function of Speech-Intelligibility Index in all conditions, even at levels that were too soft for reflex activation. This could be because of postsurgical differences in sensitivity, the more advanced age of poststapedotomy group, or differences in medial olivocochlear inhibition. For loud speech, patient performance fell nearly linearly with increases in the low-frequency masker, but control participants' performance declined little as the signal to noise ratio declined from +5 to -5 dB, and then fell rapidly as the ratio declined to -15 dB. This plateau in the masking function did not occur for the patients. Masking functions obtained with the gated low-frequency masker were either highly similar or poorer to those obtained with a continuous masker, suggesting that the use of a continuous low frequency masker did not result in significant reflex adaptation. CONCLUSIONS: The stapedius reflex appears to offer some protection from the upward spread of masking of speech by background low-frequency noise at moderate levels, but not at high levels.


Asunto(s)
Enmascaramiento Perceptual/fisiología , Reflejo Acústico/fisiología , Percepción del Habla/fisiología , Estapedio/fisiopatología , Cirugía del Estribo , Adulto , Audiometría de Tonos Puros , Umbral Auditivo , Estudios de Casos y Controles , Femenino , Humanos , Masculino , Persona de Mediana Edad , Ruido , Estapedio/fisiología , Tendones/cirugía , Adulto Joven
7.
J Acoust Soc Am ; 133(1): 417-24, 2013 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-23297913

RESUMEN

Previous psychophysical work on sound localization in humans has proposed that a midline channel be added to the current two-channel model of mammalian sound localization mechanisms. Evidence for this third channel has been found in interaural time difference (ITD) studies with low-frequency tones, and interaural level difference (ILD) studies with both high- and low-frequency tones. The latter is interesting because it suggests that, despite the fact that low frequencies do not generate significant ILDs for humans in natural settings, there is a constancy of ILD coding mechanisms across the frequency domain. To complement this finding, the present study sought to determine whether the three-channel model holds for ITDs at high frequencies. In three experiments, a selective adaptation paradigm was used in combination with transposed tones to probe for the existence of three (left, right, and midline) perceptual channels for sound source azimuth. The experiments provided evidence for lateral hemifield ITD channels but little evidence for a midline ITD channel at high frequencies.


Asunto(s)
Oído/fisiología , Localización de Sonidos , Estimulación Acústica , Adaptación Psicológica , Adulto , Análisis de Varianza , Umbral Auditivo , Humanos , Persona de Mediana Edad , Psicoacústica , Factores de Tiempo , Adulto Joven
8.
J Acoust Soc Am ; 132(1): EL22-8, 2012 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-22779568

RESUMEN

Two experiments measured human sensitivity to temporal jitter in 25-click trains with inter-click intervals (ICIs) between 5 and 100 ms. In a naturalistic experiment using wideband clicks, jitter thresholds were a nonmonotonic function of ICI, peaking for ICIs near 40-60 ms. In a subsequent experiment, clicks were high-passed and presented against a low-frequency noise masker. Jitter threshold vs ICI functions lost the positive slope over short ICIs but retained the negative slope at long ICIs. The same behavior was seen in click rate discrimination tasks. Different processes mediate regularity analysis for click trains with ICIs above and below 40-60 ms.


Asunto(s)
Percepción del Habla/fisiología , Estimulación Acústica , Adulto , Umbral Auditivo/fisiología , Femenino , Humanos , Masculino , Persona de Mediana Edad , Ruido , Percepción de la Altura Tonal/fisiología , Adulto Joven
9.
J Acoust Soc Am ; 131(5): 4023-9, 2012 May.
Artículo en Inglés | MEDLINE | ID: mdl-22559375

RESUMEN

The current understanding of mammalian sound localization is that azimuthal (horizontal) position assignments are dependent upon the relative activation of two populations of broadly-tuned hemifield neurons with overlapping medial borders. Recent psychophysical work has provided evidence for a third channel of low-frequency interaural time difference (ITD)-sensitive neurons tuned to the azimuthal midline. However, the neurophysiological data on free-field azimuth receptive fields, especially of cortical neurons, has primarily studied high-frequency cells whose receptive fields are more likely to have been shaped by interaural level differences (ILDs) than ITDs. In four experiments, a selective adaptation paradigm was used to probe for the existence of a midline channel in the domain of ILDs. If no midline channel exists, symmetrical adaptation of the lateral channels should not result in a shift in the perceived intracranial location of subsequent test tones away from the adaptors because the relative activation of the two channels will remain unchanged. Instead, results indicate a shift in perceived test tone location away from the adaptors, which supports the existence of a midline channel in the domain of ILDs. Interestingly, this shift occurs not only at high frequencies, traditionally associated with ILDs in natural settings, but at low frequencies as well.


Asunto(s)
Localización de Sonidos/fisiología , Estimulación Acústica/métodos , Adulto , Análisis de Varianza , Humanos , Juicio/fisiología , Persona de Mediana Edad , Modelos Biológicos , Percepción de la Altura Tonal/fisiología , Espectrografía del Sonido
10.
Neurosci Biobehav Rev ; 36(2): 889-900, 2012 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-22101111

RESUMEN

Heffner (2004) provided an overview of data on the evolutionary pressures on sound localization acuity in mammals. Her most important finding was that sound localization acuity was most strongly correlated with width of field of best vision. This correlation leaves unexplained the mechanism through which evolutionary pressures affect localization acuity in different mammals. A review of the neurophysiology of binaural sound localization cue coding, and the behavioural performance it supports, led us to two hypotheses. First, there is little or no evidence that the neural mechanisms for coding binaural sound location cues, or the dynamic range of the code, vary across mammals. Rather, the neural coding mechanism is remarkably constant both across species, and within species across frequency. Second, there is no need to postulate that evolutionary pressures are exerted on the cue coding mechanism itself. We hypothesize instead that the evolutionary pressure may be on the organism's ability to exploit a 'lower envelope principle' (after Barlow, 1972).


Asunto(s)
Umbral Auditivo/fisiología , Lateralidad Funcional/fisiología , Teoría Psicológica , Localización de Sonidos/fisiología , Estimulación Acústica , Animales , Humanos , Mamíferos/fisiología
11.
Anesthesiol Clin ; 29(2): 213-32, 2011 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-21620339

RESUMEN

The use of regional anesthesia (RA) improves cost benefit (hospital-centered) and cost utility (patient-centered) over general anesthesia with volatile agents (GAVA), based upon research in outpatient populations. To make the cost savings a reality, the authors recommend: (1) avoidance of GAVA or at least volatile agents, (2) adopting published postanesthesia care unit (PACU)-bypass criteria conducive to RA, (3) maximizing PACU-bypass rates, and (4) utilizing a block induction area. Inpatient-based acute pain services are not uniform, which makes cost analyses and comparison between practices unreliable. Additional review and commentary address surgical site infections, cancer recurrence, blood transfusions, and chronic postsurgical pain.


Asunto(s)
Anestesia de Conducción/economía , Manejo del Dolor , Enfermedad Aguda , Análisis Costo-Beneficio , Humanos , Tiempo de Internación , Recurrencia Local de Neoplasia/prevención & control , Náusea y Vómito Posoperatorios/prevención & control , Ultrasonografía Intervencional
12.
Ear Hear ; 32(1): 114-20, 2011 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-20808226

RESUMEN

OBJECTIVES: Periodic alternations of the interaural correlation of a noise stimulus evoke an auditory steady state response that can be measured at the scalp, providing an objective measure of binaural integration. The purpose of this study was to examine the effect of interaural level differences on this steady state response. DESIGN: Auditory steady state responses at 4 and 8 Hz were recorded to 4 Hz cycles of interaural correlation change of a Gaussian noise in normal-hearing listeners. Responses were recorded with symmetric presentation levels of 80, 60, and 40 dB SPL and with interaural asymmetries ranging from 10 to 40 dB, varying in 10-dB steps. RESULTS: The 8 Hz response was sensitive to interaural level asymmetry and fell to 50% strength at an asymmetry of 18 dB, although the response was detectable to an asymmetry of 30 dB. A simultaneously present 4 Hz response showed no sensitivity to interaural level difference. Significant responses were recorded in all participants. CONCLUSIONS: The 8 Hz auditory steady state response to a 4 Hz change in noise interaural correlation might be useful as an objective measure of binaural integration in asymmetric hearing loss. Response amplitude is more negatively affected by small amounts of interaural asymmetry than by large reductions in overall presentation level.


Asunto(s)
Estimulación Acústica/métodos , Audiometría de Respuesta Evocada , Pruebas de Audición Dicótica , Corteza Auditiva/fisiología , Umbral Auditivo/fisiología , Femenino , Lateralidad Funcional/fisiología , Humanos , Masculino , Valores de Referencia , Adulto Joven
13.
J Am Acad Audiol ; 21(6): 404-8, 2010 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-20701837

RESUMEN

BACKGROUND: Auditory gap detection is a measure of temporal acuity. The paradigm comes in two forms, distinguished by whether the sounds bounding the silent period are the same (within channel [WC]) or different (between channel [BC]). PURPOSE: The purpose of this study was to test normal children and children referred for auditory processing disorder (APD) assessment, with both gap detection paradigms. RESEARCH DESIGN: Best gap durations (i.e., shortest reliably detected gaps) were measured in a two-interval, two-alternative forced-choice design embedded within a modified method of limits, for both WC and BC paradigms, with stimuli presented at 55 dB HL. STUDY SAMPLE: Sixteen control children and 20 children referred for APD assessment participated in the study. Of the 20 referred children, 9 were diagnostically positive for APD (APD+), and 11 were negative (APD-). The mean age of children in all three groups was 10-11 yr. DATA COLLECTION AND ANALYSIS: Data collected were best gap durations for each paradigm, for each child. Group differences were assessed using Kruskal-Wallis analyses of variance. RESULTS: WC best gap durations were very similar across the three participant groups. BC best gap durations varied significantly between listener groups, with the greatest difference being between controls and APD+ samples. CONCLUSIONS: BC best gap durations differed among the listener groups while WC ones did not. This suggests that the relative timing perceptual operations required by the BC task are more susceptible to the perceptual disturbances in APD than is the simple event detection required by the WC task.


Asunto(s)
Estimulación Acústica/métodos , Atención , Percepción Auditiva , Trastornos de la Percepción Auditiva/diagnóstico , Umbral Auditivo , Pruebas Auditivas/métodos , Percepción del Tiempo , Niño , Femenino , Humanos , Percepción Sonora , Masculino , Percepción de la Altura Tonal
14.
Hear Res ; 268(1-2): 67-74, 2010 Sep 01.
Artículo en Inglés | MEDLINE | ID: mdl-20457238

RESUMEN

Neurophysiological and psychophysical evidence has driven the formulation of a hemifield model of mammalian sound localization in which the perceived location of a stimulus is based on the relative activity of two hemifield-tuned azimuthal channels that are broadly responsive to contralateral auditory space and have overlapping medial borders. However, neurophysiological work in mammals has consistently found neurons selective for sound sources at the midline, which may indicate the existence of a third, 'midline', perceptual channel. In three experiments, the existence of three (left, right, midline) perceptual channels for azimuth in man was examined using auditory selective adaptation paradigms. If no midline channel exists, exposure to highly lateralized, symmetrical adaptor frequencies should not result in a shift in the perceived intracranial location of subsequent test tones away from the adaptors because the relative activation of the two hemifield channels will remain the same. Rather, our results indicate a shift in perceived test tones towards the azimuthal midline. This result can best be explained by a perceptual/neural channel tuned to sounds located along the midline. The present study gives the first psychophysical evidence of a midline channel serving human auditory localization, adding to the earlier evidence on the same point from animal neurophysiological studies.


Asunto(s)
Vías Auditivas/fisiología , Audición , Modelos Psicológicos , Localización de Sonidos , Estimulación Acústica , Adulto , Audiometría , Umbral Auditivo , Humanos , Persona de Mediana Edad , Psicoacústica , Factores de Tiempo , Adulto Joven
15.
Hear Res ; 245(1-2): 18-23, 2008 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-18761067

RESUMEN

A temporal processing advantage is thought to underlie the left hemisphere dominance for language. One measure of a temporal processing advantage is temporal acuity or resolution. A standard paradigm for measuring auditory temporal resolution is gap detection in its "within-channel" and "between-channel" forms. Previous experiments investigating a right ear advantage for within-channel gap detection have yielded conflicting results, and between-channel gap detection has not previously been studied for ear differences. In the present study, the two types of gap detection task were employed, under each of three contralateral masking conditions (no noise, continuous noise and interrupted noise). An adaptive tracking procedure was used to measure the minimal detectable gap at each ear (and therefore, the temporal acuity of the contralateral hemisphere). A significant effect of masking noise was observed in both of the gap detection tasks. Within-channel gap threshold durations were longer in the interrupted noise condition for both ears. Between-channel gap threshold durations were shorter in the interrupted noise condition at the left ear, with a trend in the same direction at the right ear. The study found no significant difference between the ears in thresholds in either gap detection task in any of the masking conditions. This suggests that if the left cerebral hemisphere has a temporal processing advantage, then it is not in the form of acuity for temporal gap detection.


Asunto(s)
Umbral Auditivo/fisiología , Enmascaramiento Perceptual/fisiología , Estimulación Acústica , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Femenino , Humanos , Masculino , Persona de Mediana Edad , Factores de Tiempo , Adulto Joven
16.
Hear Res ; 241(1-2): 97-102, 2008 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-18565705

RESUMEN

Auditory saltation is the orderly misperception of the spatial location of repetitive click stimuli emitted from two successive locations when the inter-click intervals (ICIs) are sufficiently short. The clicks are perceived as originating not only from the actual source locations, but also from locations between them. In two tasks, the present experiment compared free-field auditory saltation for 90 degrees excursions centered in the frontal, rear, left and right acoustic hemifields, by measuring the ICI at which subjects report 50% illusion strength (subjective task) and the ICI at which subjects could not distinguish real motion from saltation (objective task). A comparison of the saltation illusion for excursions spanning the midline (i.e. for frontal or rear hemifields) with that for stimuli in the lateral hemifields (left or right) revealed that the illusion was weaker for the midline-straddling conditions (i.e. the illusion was restricted to shorter ICIs). This may reflect the contribution of two perceptual channels to the task in the midline conditions (as opposed to one in the lateral hemifield conditions), or the fact that the temporal dynamics of localization differ between the midline and lateral hemifield conditions. A subsidiary comparison of saltation supported in the left and right auditory hemifields, and therefore by the right and left auditory forebrains, revealed no difference.


Asunto(s)
Vías Auditivas/fisiología , Ilusiones , Enmascaramiento Perceptual , Localización de Sonidos , Estimulación Acústica , Femenino , Humanos , Masculino , Factores de Tiempo
17.
Hear Res ; 238(1-2): 124-32, 2008 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-17980984

RESUMEN

There are two general neurophysiological models of sound lateralization mechanisms which may be active in man. Both of the models are derived from studies in animals (one in barn owls, and one in mammals), and both have displayed some weakness in generalizability. One model advocates a population of neurons narrowly tuned to different interaural disparity values across the behaviorally relevant range, so that the cue value, and therefore the source azimuth, is represented by which neurons of the array are activated by the stimulus. The second model posits the existence of only two neural channels, each broadly tuned to interaural cue values favoring one acoustic hemifield, so that, especially for sources near the midline, cue value and therefore source azimuth is encoded by the relative activation of the two neural populations. The present article reviews three recent psychophysical studies, each using selective adaptation paradigms to probe sound lateralization mechanisms based on interaural disparities in normal human listeners. These experiments provided evidence on the frequency-specificity of interaural disparity coding and revealed its sensitivity to recent stimulus history. The data from those studies, however, also help distinguish the two lateralization models, and favor a perceptual architecture for sound lateralization in man based on the activity of two, hemifield-tuned azimuthal channels.


Asunto(s)
Corteza Auditiva/fisiología , Vías Auditivas/fisiología , Nervio Coclear/fisiología , Modelos Neurológicos , Localización de Sonidos , Estimulación Acústica , Adaptación Fisiológica , Animales , Señales (Psicología) , Potenciales Evocados Auditivos , Humanos , Percepción de la Altura Tonal , Psicoacústica , Estrigiformes
18.
Perception ; 36(6): 918-30, 2007.
Artículo en Inglés | MEDLINE | ID: mdl-17718369

RESUMEN

Three previous psychophysical studies have demonstrated that interaural time difference (ITD) coding mechanisms can undergo frequency-specific, selective adaptation. We sought to determine whether this phenomenon extends to the pitch domain, by employing the same psycho-physical paradigm as one used previously, but with harmonic tone complexes lacking energy at the fundamental frequency. Ten normal listeners participated in experiment 1. Psychometric functions for ITDs were obtained for harmonic tone complexes with fundamental frequencies of 110 Hz and 185 Hz, before and after selective adaptation with complexes of the same fundamental frequencies lateralised to opposite sides. In experiment 1, each subject was tested twice. On separate days, subjects were tested with 110 Hz and 185 Hz stimuli that were either partially resolvable complexes or unresolvable ones. Both partially resolved and unresolved stimuli supported adaptation, and at both fundamental frequencies. In experiment 2, which employed nine listeners, the adaptor tone complexes were presented in conjunction with a diotic noise background designed to mask difference tones generated by the adaptor stimuli. The use of the masker had little effect on the mean strength of the adaptation effected by the unresolved adaptor stimuli, and only slightly weakened the adaptation effect found with the partially resolved adaptor stimuli. Taken together, these data constitute the first demonstration of selective adaptation exerted on a central mechanism in the pitch domain.


Asunto(s)
Adaptación Fisiológica , Discriminación de la Altura Tonal/fisiología , Estimulación Acústica , Adulto , Humanos , Psicoacústica , Psicometría
19.
Hear Res ; 224(1-2): 93-100, 2007 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-17223297

RESUMEN

Two experiments examined the effect of highly lateralized adaptor tone pulses on the perceived intracranial location of subsequent test tones. In Experiment 1, adaptor tones of each of two frequencies, highly lateralized to opposite sides by a quarter-period interaural time difference (ITD), were found to shift the perceived intracranial location of test tones of each adaptor frequency away from the side of the adaptor. The shift in perceived location was seen for all test tone ITDs with the same sign as the adaptor tone, and sometimes extended to include test tones with small ITDs favoring the opposite ear. The generality of the effect across test tone ITDs of the same sign as the adaptor suggests that the human auditory lateralization system is built of two (left, right) hemifield-tuned azimuthal channels, and that perceived lateral location depends on the relative outputs of those two channels. In Experiment 2, the perceived location of test tones lateralized by ITD was studied in the same listeners at each of the same two frequencies, but after selective adaptation with tone pulses of only one frequency and laterality. The perceived lateral position of test tones with the same frequency as that of the adaptor underwent the same changes as seen in Experiment 1. The perceived lateral position of test tones of the nonadapted frequency usually shifted weakly in the opposite direction, i.e., in the direction expected if the second adaptor from Experiment 1 had actually been present. These data have implications both for the processes mediating selective adaptation using contingent stimuli, and for the azimuthal tuning of auditory spatial channels in man.


Asunto(s)
Localización de Sonidos/fisiología , Estimulación Acústica , Adaptación Fisiológica , Adolescente , Adulto , Femenino , Humanos , Masculino , Modelos Psicológicos , Discriminación de la Altura Tonal/fisiología , Psicoacústica
20.
Brain Res ; 1124(1): 126-41, 2006 Dec 08.
Artículo en Inglés | MEDLINE | ID: mdl-17069776

RESUMEN

Performance on perceptual tasks requiring the discrimination of brief, temporally proximate or temporally varying sensory stimuli (temporal processing tasks) is impaired in some individuals with developmental language disorder and/or dyslexia. Little is known about how these temporal processes in perception develop and how they relate to language and reading performance in the normal population. The present study examined performance on 8 temporal processing tasks and 5 language/reading tasks in 120 unselected readers who varied in age over a range in which reading and phonological awareness were developing. Performance on all temporal processing tasks except coherent motion detection improved over ages 7 years to adulthood (p<0.01), especially between ages 7 and 13 years. Independent of these age effects, performance on all 8 temporal processing tasks predicted phonological awareness and reading performance (p<0.05), and three auditory temporal processing tasks predicted receptive language function (p<0.05). Furthermore, all temporal processing measures except within-channel gap detection and coherent motion detection predicted unique variance in phonological scores within subjects, whereas only within-channel gap detection performance explained unique variance in orthographic reading performance. These findings partially support the (Farmer, M.E., Klein, R.M., 1995. The evidence for a temporal processing deficit linked to dyslexia: A review. Psychon. Bull. Rev. 2, 460-493) notion of there being separable auditory and visual perceptual contributions to phonological and orthographic reading development. The data also are compatible with the view that the umbrella term "temporal processing" encompasses fundamentally different sensory or cognitive processes that may contribute differentially to language and reading performance, which may have different developmental trajectories and be differentially susceptible to pathology.


Asunto(s)
Percepción Auditiva/fisiología , Discriminación en Psicología/fisiología , Desarrollo Humano , Lectura , Percepción Visual/fisiología , Adolescente , Adulto , Factores de Edad , Niño , Femenino , Humanos , Modelos Lineales , Masculino , Persona de Mediana Edad , Fonética , Factores de Tiempo
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