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At least 1,657 records · Page 92Linked to original sources
PubMed1994

Population responses to multifrequency sounds in the cat auditory cortex: four-tone complexes.

Population responses to two-tone and four-tone sounds were recorded in primary auditory cortex of anesthetized cats. The stimuli were delivered through a sealed, calibrated sound delivery system. The envelope of the neural signal (short time mean absolute value, MABS) was recorded extracellularly from six microelectrodes simultaneously. A new method was developed to describe the responses to the four-tone complexes. The responses were represented as sums of contributions of different orders. The first order contributions described the effect of the single frequencies appearing in the stimulus. The second order contributions described the modulatory effect of the pairs of frequencies. Higher order contributions could in principle be computed. This paper concentrates on the mean onset responses. The extent to which the first and second order contributions described the onset responses was assessed in two ways. First, the actual responses to two-tone stimuli were compared with those predicted using the contributions computed from the four-tone stimuli. Second, the residual variance in the responses, after the subtraction of the first and second order contributions, was computed and compared with the variability in the responses to repetitions of the same stimulus. The first type of analysis showed good quantitative agreement between the predicted and the measured two-tone responses. The second type of analysis showed that the first and second order contributions were often sufficient to predict the responses to four-tone stimuli up to the level of the variability in the responses to repetitions of a single stimulus. In conjunction with the results of the companion paper (Nelken et al., 1994a) it is concluded that the onset responses to multifrequency sounds are shaped mainly by the single frequency content of the sound and by two-tone interactions, and that higher order interactions contribute much less to the responses. It follows that single-tone effects and two-tone interactions are necessary and sufficient to explain the mean population onset responses to the four-tone stimuli. More information can be coded in the temporal evolution of the responses.

Acoustic Stimulation↗
PubMed2004

Use of internal artificial vaginas for breeding soundness evaluation in range bulls: an alternative for electroejaculation allowing observation of sex drive and mating ability.

The objective of this study was to test the efficacy of an inexpensive, reusable internal artificial vagina (IAV) developed for breeding soundness evaluation of range beef bulls. In addition, sexual behavior during semen collection by IAV was compared to behavior during pasture breeding. Breeding soundness exams (BSEs) were conducted on 165 bulls in two consecutive years (96 in Year 1 and 69 in Year 2). In Year 1, BSEs were done twice in all bulls, once by a conventional protocol using electroejaculation (EEJ), followed by the IAV method, one week later. In Year 2, all BSEs were done on one day; 69 bulls by the IAV method followed by EEJ in 21 bulls that failed to serve the IAV. For semen collection using an IAV, mount cows were restrained in breeding crates and an IAV was inserted into the vagina just beyond the depth of the vestibular sphincter. After each copulation, the IAV was replaced for the next bull to be tested. Semen collection by IAV was successful for all bulls that mounted and penetrated cows during the testing period (54.3 and 69.6% of the bulls served the cows with IAVs in Year 1 and 2, respectively). Semen was collected successfully by EEJ from all bulls in both years. Differences were observed between semen collection methods in semen volume and percentage of sperm staining alive; however, the differences were opposite in Year 1 and 2 and, therefore, were probably due to natural variations in time and within bull rather than the method of semen collection. Semen collection by IAV allowed the detection of problems that prevented copulation in 8 bulls (4.8%) that were determined to be satisfactory potential breeders when semen was collected by EEJ. In Year 1, breeding observations were made at pasture for 15 bulls that served, and 15 bulls that did not serve cows with an IAV. Bulls that did not serve the IAV during the test period had fewer mounts, attempts to mount, and completed services at pasture than bulls that had served the IAV, indicating that such bulls are likely to be less efficient breeders. In conclusion, IAVs might be used as an alternative to EEJ for breeding soundness evaluation in about 50-70% of range bulls. Semen collection by IAV also allows observation of sex drive and mating ability thus improves the ability to select sound breeding bulls.

Animals↗
PubMed2004

Auditory location in the irrelevant sound effect: The effects of presenting auditory stimuli to either the left ear, right ear or both ears.

Two experiments used both irrelevant speech and tones in order to assess the effect of manipulating the spatial location of irrelevant sound. Previous research in this area had produced inconclusive results (e.g., Colle, 1980). The current study demonstrated a novel finding, that sound presented to the left ear produces the greatest level of disruption. These results were explained in terms of hemispheric specialisation for processing of some supra-linguistic components in the unattended sound. Results also supported previous research by demonstrating that both forms of irrelevant sound disrupted performance on serial memory tasks (Bridges & Jones, 1996; Colle & Welsh, 1976; Jones, Alford, Bridges, Tremblay, & Macken, 1999; Jones, Miles, & Page, 1990).

Acoustic Stimulation↗
PubMed2006

Conceptual priming for environmental sounds and words: an ERP study.

In this study we examined conceptual priming using environmental sounds and visually displayed words. Priming for sounds and words was observed in response latency as well as in event-related potentials. Reactions were faster when a related word followed an environmental sound and vice versa. Moreover both stimulus types produced an N400-effect for unrelated compared to related trials. The N400-effect had an earlier onset for environmental sounds than for words. The results support the theoretical notion that conceptual processing may be similar for verbal and non-verbal stimuli.

Acoustic Stimulation↗
PubMed2006

Auditory semantic networks for words and natural sounds.

Does lexical processing rely on a specialized semantic network in the brain, or does it draw on more general semantic resources? The primary goal of this study was to compare behavioral and electrophysiological responses evoked during the processing of words, environmental sounds, and non-meaningful sounds in semantically matching or mismatching visual contexts. A secondary goal was to characterize the dynamic relationship between the behavioral and neural activities related to semantic integration using a novel analysis technique, ERP imaging. In matching trials, meaningful-sound ERPs were characterized by an extended positivity (200-600 ms) that in mismatching trials partly overlapped with centro-parietal N400 and frontal N600 negativities. The mismatch word-N400 peaked later than the environmental sound-N400 and was only slightly more posterior in scalp distribution. Single-trial ERP imaging revealed that for meaningful stimuli, the match-positivity consisted of a sensory P2 (200 ms), a semantic positivity (PS, 300 ms), and a parietal response-related positivity (PR, 500-800 ms). The magnitudes (but not the timing) of the N400 and PS activities correlated with subjects' reaction times, whereas both the latency and magnitude of the PR was correlated with subjects' reaction times. These results suggest that largely overlapping neural networks process verbal and non-verbal semantic information. In addition, it appears that semantic integration operates across different time scales: earlier processes (indexed by the PS and N400) utilize the established meaningful, but not necessarily lexical, semantic representations, whereas later processes (indexed by the PR and N600) are involved in the explicit interpretation of stimulus semantics and possibly of the required response.

Acoustic Stimulation↗
PubMed2004

The old switcheroo: when target environmental sounds elicit a novelty P3.

OBJECTIVE: Novel environmental sounds that are task-irrelevant in the novelty oddball paradigm elicit the novelty P3 or P3a with a fronto-central scalp distribution, while pure tone task-relevant stimuli elicit a P3 with a posterior topography (P3b). To determine whether stimulus nature or its function in the task modulates scalp topography, the role of the two types of stimuli during the novelty oddball task was reversed. METHODS: Brain electrical activity was recorded while 12 young adults listened to frequent tones, infrequent tones, and infrequent environmental sounds. Subjects were not informed about the infrequent tones, but were instructed to press a reaction time (RT) button when they heard the infrequent environmental sounds. RESULTS: Despite the "novelty" nature of the tones, they were associated with a posterior scalp distribution typical of the P3b. Similarly, despite the "target" nature of the environmental sounds, they were associated with a fronto-central scalp topography typical of the P3a. CONCLUSIONS: These data suggest that the elicitation of a novelty P3 depends not only on task demands but also on the physical nature of the stimulus. SIGNIFICANCE: The brain's orienting response is modulated by the contextual environment as well as the physical properties of the eliciting stimulus.

Acoustic Stimulation↗
PubMed2003

The N1 hypothesis and irrelevant sound: evidence from token set size effects.

This study investigated how increases in the number of different types of sound (token set size) within a heard but ignored sequence influence brain activity and performance in a serial recall task (the irrelevant sound effect). We tested the hypothesis that brain processes affected by the refractory state of the neuronal populations involved in generating the auditory N1 play a role in the memory disruption produced by irrelevant sound. Auditory event-related potentials (ERPs) were recorded when volunteers performed a serial recall task that required remembering lists of visually presented numbers that were followed by a distractor-filled retention interval. The results showed that both increments in set size from 1 to 2 and from 2 to 5 elicited an increase of the N1 amplitude. Furthermore, increases in set size from 2 to 5, but not from 1 to 2, caused a significant decrease of the serial recall performance. This result suggested that, if N1 were to play a role in the disruption produced by irrelevant sound, the processes underlying the N1 wave may only serve as a necessary rather than a sufficient condition for disruption.

Acoustic Stimulation↗
PubMed2004

Middle ear and cochlear disorders result in different DPOAE growth behaviour: implications for the differentiation of sound conductive and cochlear hearing loss.

Input/output functions of distortion product otoacoustic emissions (DPOAE I/O-functions) give an insight into the compressive, non-linear sound processing of the cochlea. With an inner ear dysfunction a steeper I/O-function is observed. Due to the linear sound processing of the middle ear, one can assume that the DPOAE growth behaviour remains unaltered with a sound conduction dysfunction. If that is true, a differentiation between middle and inner ear dysfunction will be possible by using the slope of DPOAE I/O-functions as a means for assessing cochlear compression. In order to test that hypothesis, DPOAE I/O-functions were recorded in a wide primary tone level range at up to 8 f2 frequencies between 2.0 and 8.0 kHz (15 dB SPL < L2< 60 dB SPL; L1=0.46 L2 + 41 dB SPL; f2/f1=1.2) in guinea pigs in which middle (saline solution in the bulla) and inner ear (exposure to loud broadband noise) disorders were induced. Middle ear dysfunction resulted in a reduction of the DPOAE amplitude independent of the primary tone level. Consequently, DPOAE growth behaviour was not affected. In contrast to that, during cochlear impairment, steepened DPOAE I/O-functions were observed reflecting loss of compression of the cochlear amplifier. Accordingly, DPOAE I/O-functions allow a differentiation between middle and inner ear dysfunction. Further studies will have to show the usability of this method for clinical diagnostics, e.g. for detecting sound conduction disturbances in newborn hearing screening due to amniotic fluid or Eustachian tube dysfunctions during the early postnatal period.

Animals↗
PubMed2005

Effects of sound bandwidth on fMRI activation in human auditory brainstem nuclei.

Few neuro-imaging studies of the auditory system have examined the dependence of brain activation on sound bandwidth, a fundamental stimulus parameter, and none have examined bandwidth dependencies in the brainstem. The present study examined the effect of bandwidth on human brainstem activation using fMRI, an indicator of population neural activity. The studied stimuli (broadband, two-, one-, and third-octave continuous noise) activated three brainstem centers: cochlear nucleus, superior olivary complex, and inferior colliculus. Activation could be confidently attributed to these nuclei because it was appropriately punctate (given the small size of the imaged nuclei) and appropriately located (as determined from histological atlases). Activation in all three imaged centers increased monotonically with increasing bandwidth when either stimulus spectrum level or energy was held constant. Supplementary experiments indicated that the measured bandwidth dependencies were not contaminated by the extraneous sounds produced by the scanner. Increases in fMRI activation with increasing bandwidth would be expected from populations of neurons having a single best frequency and only excitatory responses to sound, but not necessarily from lower auditory system neurons with their often more complex responses. Our results provide basic information for designing auditory neuro-imaging studies that need to control for, or manipulate sound bandwidth.

Acoustic Stimulation↗
PubMed2004

Vestibular neuritis in a child with otitis media with effusion; clinical application of vestibular evoked myogenic potential by bone-conducted sound.

Vestibular evoked myogenic potential (VEMP) has been applied for patients with vestibulo-cochlear disorders. The impairment of the sound transmission due to middle ear pathology affects VEMP results. In children, otitis media with effusion (OME) is well documented and it is difficult to apply conventional VEMP in such cases. To overcome the attenuation of stimulation due to middle ear pathology, VEMP by bone-conducted sound has been developed. We report a 3-year-old girl with vestibular neuritis and OME as a representative case of clinical application of VEMP by bone-conducted sound. VEMP by bone-conducted sound can be an alternative method to elicit vestibular-dependent potential.

Bone Conduction↗
PubMed2006

Dimensions of early speech sound disorders: A factor analytic study.

UNLABELLED: The goal of this study was to classify children with speech sound disorders (SSD) empirically, using factor analytic techniques. Participants were 3-7-year olds enrolled in speech/language therapy (N = 185). Factor analysis of an extensive battery of speech and language measures provided support for two distinct factors, representing the skill dimensions of articulation/phonology and semantic/syntactic skills. To validate these factors, 38 of the children were followed to school age to re-evaluate speech and language skills and assess reading/spelling achievement. The validity of the two factors was supported by their differential associations with school-age reading and spelling achievement, persistence of SSD, and affection status in family members. A closer relationship of the family member to the proband and male gender predicted higher odds of a disorder. The findings suggest that articulation/phonology and language abilities are at least partially independent in children with SSD and that these constructs have distinct clinical and biological correlates. LEARNING OUTCOMES: The reader will develop knowledge about subtypes of speech sound disorders, understand the relationship between early speech sound disorders and later reading and spelling difficulties, and obtain information concerning familial transmission of speech sound disorders.

Age Factors↗
PubMed2006

Cortical interactions underlying the production of speech sounds.

UNLABELLED: Speech production involves the integration of auditory, somatosensory, and motor information in the brain. This article describes a model of speech motor control in which a feedforward control system, involving premotor and primary motor cortex and the cerebellum, works in concert with auditory and somatosensory feedback control systems that involve both sensory and motor cortical areas. New speech sounds are learned by first storing an auditory target for the sound, then using the auditory feedback control system to control production of the sound in early repetitions. Repeated production of the sound leads to tuning of feedforward commands which eventually supplant the feedback-based control signals. Although parts of the model remain speculative, it accounts for a wide range of kinematic, acoustic, and neuroimaging data collected during speech production and provides a framework for investigating communication disorders that involve malfunction of the cerebral cortex and interconnected subcortical structures. LEARNING OUTCOMES: Readers will be able to: (1) describe several types of learning that occur in the sensory-motor system during babbling and early speech, (2) identify three neural control subsystems involved in speech production, (3) identify regions of the brain involved in monitoring auditory and somatosensory feedback during speech production, and (4) identify regions of the brain involved in feedforward control of speech.

Brain Mapping↗
PubMed2003

Do we need a systematic activation of alarm soundings for blood pressure monitoring for the safety of ICU patients?

PURPOSE: Evaluation of a protocol of activation-deactivation of alarm soundings on noninvasive mean arterial pressure (MAP) monitoring. MATERIALS AND METHODS: 103 patients were analyzed. Alarm soundings on noninvasive MAP were either activated (group A) or inactivated (group NA) according to a protocol based on patient's hemodynamic status. RESULTS: In the first part of the study (11 periods of 24 hours), we informed the nursing staff before data collection. In the second part of the study (11 periods of 24 hours), we did not inform the nursing staff before data collection. Results of the two parts were assembled and the final analysis consisted of 3,304 hours of monitoring with 12,839 noninvasive MAP measurements, 6,354 in group A and 6,485 in group NA. In group A, 75 of 944 (8%) of abnormal measurements were detected or managed with a delay > 15 minutes and among them 16 required a therapeutic adjustment. In group NA, 140 of 265 (53%) of abnormal measurements were detected or managed with a delay > 15 minutes and among them, only one required a therapeutic adjustment. The number of alarm soundings avoided in group NA was 286. CONCLUSION: In this study, a systematic activation of alarm soundings for non-invasive blood pressure monitoring seemed unnecessary for the safety of ICU patients.

Blood Pressure↗
PubMed2006

Sound conditioning protects hearing by activating the hypothalamic-pituitary-adrenal axis.

Sound conditioning primes the auditory system to low levels of acoustic stimuli and reduces damage caused by a subsequent acoustic trauma. This priming activates the HPA axis resulting in the elevation of plasma corticosterone with a consequent upregulation of glucocorticoid receptors (GR) in the cochlea and the paraventricular nucleus (PVN) of the hypothalamus in the mouse. This protective effect is blocked by adrenalectomy or pharmacological treatment with RU486 + metyrapone. Sound conditioning prevents GR down-regulation induced by acoustic trauma and subsequently enhances GR activity in spiral ganglion neurons. Increased SRC-1 expression, triggered by sound conditioning, positively correlates with the upregulation of GR in the cochlea. These findings will help to define the cellular mechanisms responsible for protecting the auditory system from hearing loss by sound conditioning.

Acoustic Stimulation↗
PubMed2003

Modulatory effect of inaudible high-frequency sounds on human acoustic perception.

We evaluated the effects of the intensity of an inaudible high-frequency component (HFC) of sound on human responses by employing a multi-parametric approach consisting of behavioral measurements of the comfortable listening level (CLL), psychological measurements of the subjective impression of sounds, and physiological measurements using electroencephalogram (EEG). Increasing the intensity of the inaudible HFC resulted in a significant increase in the CLL, the subjective impression of sounds, and the occipital alpha frequency component of the spontaneous EEG. These effects peaked with an increase of 6 dB in HFC intensity. The results of the present study suggest that the intensity of inaudible HFC non-linearly modulates human sound perception.

Acoustic Stimulation↗
PubMed2004

The processing of speech and non-speech sounds in aphasic patients as reflected by the mismatch negativity (MMN).

This study compared the discrimination of speech and non-speech sounds in left-hemisphere stroke patients with aphasia and healthy controls by recording event-related potentials (ERPs) and behavioural responses. It was found that the mismatch negativity (MMN) amplitude for vowel and duration changes in speech sounds was diminished in the patients. In contrast, there was no significant difference between the groups in the MMN for comparable frequency and duration changes in non-speech sounds. In the behavioural session, the patients were slower than the control subjects in discriminating duration changes of both types of sounds. These results suggest that left-hemisphere lesions have differential effects on the discrimination of speech and acoustic features indicating that they have separate neural substrates.

Acoustic Stimulation↗
PubMed2005

Recruitment of fusiform face area associated with listening to degraded speech sounds in auditory-visual speech perception: a PET study.

For the fast and accurate cognition of external information, the human brain seems to integrate information from multi-sensory modalities. We used positron emission tomography (PET) to identify the brain areas related to auditory-visual speech perception. We measured the regional cerebral blood flow (rCBF) of young, normal volunteers during the presentation of dynamic facial movement at vocalization and during a visual control condition (visual noise), both under the two different auditory conditions of normal and degraded speech sounds. The subjects were instructed to listen carefully to the presented speech sound while keeping their eyes open and to say what they heard. The PET data showed that elevation of rCBF in the right fusiform gyrus (known as the "face area") was not significant when the subjects listened to normal speech sound accompanied by a dynamic image of the speaker's face, but was significant when degraded speech sound (filtered with a 500 Hz low-pass filter) was presented with the facial image. The results of the present study confirm the possible involvement of the fusiform face area (FFA) in auditory-visual speech perception, especially when auditory information is degraded, and suggest that visual information is interactively recruited to make up for insufficient auditory information.

Acoustic Stimulation↗
PubMed2005

Sound level dependence of the primary auditory cortex: Simultaneous measurement with 61-channel EEG and fMRI.

Sound level dependence has been investigated for years with event-related potentials (ERP). A serotonergic modulation of the sound level dependence only of the primary auditory cortex but not of the auditory association cortex has been suggested by a number of clinical and preclinical studies. Therefore, a precise covering of the activity of the primary auditory cortex seems necessary if sound level dependence is used as an indicator of the central serotonergic system. Recent fMRI studies described a pronounced sound level dependence only in the Heschl gyrus/primary auditory cortex but not in auditory association areas. In the present simultaneous 61-channel EEG and fMRI study investigating fourteen healthy subjects, we found a high correlation between the loudness-dependent change of the extent of fMRI activation (number of activated voxels) and the corresponding changes of the mean current source density within the same region of interest covering the primary auditory cortex (r = 0.84, P < 0.001). Our findings suggest a close relationship between the fMRI signal and event-related potential activity. In addition, the correspondence of the ERP-based data and the fMRI results further supports the validity of the ERP localization approach.

Acoustic Stimulation↗