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PubMed1997

Changing-loudness aftereffects: slope of response functions and spectral dependence.

Aftereffects of azimuthal auditory motion may have two components. A sensory component is inferred from strong aftereffects, because they are spectrally dependent and have shallower response functions than those for non-adaptation. Neither property applies to weak aftereffects, suggesting a cognitive component. Two experiments determined whether changing-loudness aftereffects (CLA) might be understood similarly. In a single-interval forced-choice procedure, listeners responded "growing softer" or "growing louder" to test stimuli changing in intensity. In Exp. 1, adapting and test stimuli were diotic and had the same 1-kHz sinusoidal carrier. Although response functions following adaptation were displaced from response functions for non-adaptation-indicating CLA-their slopes were broadly similar. In Exp. 2, stimuli were monotic; adapting frequency was 1 kHz and test frequencies were between 0.5 and 2.0 kHz. CLA was present in most adaptation conditions, but was strongest when the test frequency was 1.0 kHz; functions' slopes again evinced no systematic variation. The two-component hypothesis for CLA is supported by spectral dependence alone. It is argued that the slope of response functions is due to the nulling procedures for measuring auditory aftereffects. The slope depends on whether the adapted property is processed by "direct" and "indirect" mechanisms; aftereffects tap "direct" mechanisms alone, which may affect sensitivity during measurement.

Adult↗
PubMed1985

Responses to pure tones and linear FM components of the CF-FM biosonar signal by single units in the inferior colliculus of the mustached bat.

The responses of 682 single-units in the inferior colliculus (IC) of 13 mustached bats (Pteronotus parnellii parnellii) were measured using pure tones (CF), frequency modulations (FM) and pairs of CF-FM signals mimicking the species' biosonar signal, which are stimuli known to be essential to the responses of CF/CF and FM-FM facilitation neurons in auditory cortex. Units were arbitrarily classified into 'reference frequency' (RF), 'FM2' and 'Non-echolocation' (NE) categories according to the relationship of their best frequencies (BF) to the biosonar signal frequencies. RF units have high Q10dB values and are tuned to the reference frequency of each bat, which ranged between 60.73 and 62.73 kHz. FM2 units had BF's between 50 and 60 kHz, while NE units had BF's outside the ranges of the RF and FM2 classes. PST histograms of the responses revealed discharge patterns such as 'onset', 'onset-bursting' (most common), 'on-off', 'tonic-on','pauser', and 'chopper'. Changes in discharge patterns usually resulted from changes in the frequency and/or intensity of the stimuli, most often involving a change from onset-bursting to on-off. Different patterns were also elicited by CF and FM stimuli. Frequency characteristics and thresholds to CF and FM stimuli were measured. RF neurons were very sharply tuned with Q10dB's ranging from 50-360. Most (92%) also responded to FM2 stimuli, but 78% were significantly more sensitive (greater than 5 dB) to CF stimuli, and only 3% had significantly lower thresholds to FM2. The best initial frequency for FM2 sweeps in RF units was 65.35 +/- 2.138 kHz (n = 118), well above the natural frequency of the 2nd harmonic. FM2 and NE units were indistinguishable from each other, but were quite different from RF units: 41% of these two classes had lower thresholds to CF, 49% were about equally sensitive, and 10% had lower thresholds to FM. For FM2 units, mean best initial frequency for FM was 60.94 kHz +/- 3.162 kHz (n = 114), which is closely matched to the 2nd harmonic in the biosonar signal. Very few units (5) responded only to FM signals, i.e., were FM-specialized. The characteristics of spike-count functions were determined in 587 units. The vast majority (79%) of RF units (n = 228) were nonmonotonic, and about 22% had upper-thresholds.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1980

[Annoyance and loudness measurements in auditory fatigue and recovery under different sound exposures].

In the course of two experimental studies the individual evaluations of noise annoyance during sound exposure were compared with the experimental auditory fatigue (TTS) and the recovery functions. In both studies, in fourteen young men with normal hearing capacity, a temporary threshold shift was built up and then the subjects were submitted during the recovery period to different second-noise levels (narrow band noise and white noise). The loudness estimations and the evaluations of noise annoyance were scaled at the same points as TTS was measured. The poststimulatory recovery of hearing was significantly delayed, even at noise levels of 65 and 75 db. The evaluations of loudness and noise annoyance corresponded well with the recovery of hearing. In the first experiment, the mean values of noise annoyance ratings increased after 16 min of the second noise exposure, in spite of a further decrement of auditory fatigue. In the second experiment, the mean values of noise annoyance ratings remained almost unchanged during the secondary noise exposure. Regarding individual evaluations, however, the noise annoyance ratings of half of the subjects increased whereas the other half decreased. These results are interpreted as a habituation respectively a sensitization process.

Acoustic Stimulation↗
PubMed2001

[Loudness scaling in children].

BACKGROUND AND OBJECTIVE: Loudness measurements in children have been carried out using different psychoacoustical methods. Besides absolute magnitude estimation (AME) and cross modality matching (CMM) category and non-category loudness scalings have been performed. However, there is a lack of systematic evaluation in loudness scalings with children. PATIENTS/METHODS: A clinically feasible categorical method is presented which was evaluated in 10 normally hearing children of 7 to 8 years. Furthermore, measurements with hearing disabled children were performed in the framework of hearing aid evaluation. RESULTS: Normal hearing children scaled slightly louder than a group of adult subjects with normal hearing. Regarding the shape of the loudness functions measured they were very similar. Particularly, they showed a steeper course at higher levels than for low input signals. Intraindividual scatter of the loudness judgements was larger for children than for adults. However, high correlation appeared between the data across test and retest. Hence, the outcome of the scalings appears to be sufficient reliable. CONCLUSIONS: Clinical measurements confirmed that the method is appropriate for children from approximately 5-10 years. Loudness judgements became more consistent and more subtly differentiated with increasing age and decreasing hearing loss. Especially with view of hearing aid evaluation the method can give valuable indications because of the possibility to directly measure individual loudness over a broad range of levels and frequencies.

Adult↗
PubMed1980

Binaural response-specific bands in primary auditory cortex (AI) of the cat: topographical organization orthogonal to isofrequency contours.

The spatial distribution of neurons with different binaural response properties has been studied within the three dimensions of the primary auditory cortex (AI) in the cat. Using dichotic stimulation, 92% of neurons encountered could be classified into either the excitatory/excitatory (EE) or excitatory/inhibitory (EI) interaction class. In nearly all of almost 800 penetrations introduced along radial axes, all neurons encountered along a given penetration were of the same binaural response class. Neurons of different binaural interaction classes were spatially segregated within the plane of the cortex. Electrode penetrations made parallel to isofrequency contours traversed the mediolateral extent of AI through the middle layers of the cortex. A sharp segregation of units by binaural response class was observed in these penetrations, i.e. sequences of neurons that were all of the EE class alternated with sequences of EI neurons. The regions of uniform response to binaural stimulation formed radially organized topographical subunits that were elongated along the rostrocaudal dimension of AI. These binaural interaction bands intersect the lines of re-representation of the cochlear sensory epithelium ('isofrequency contours') and, thus, create subdivisions of AI that each contain a representation of the entire audible frequency domain. The implications of these results for the concept of AI as a unitary element in auditory processing are discussed.

Acoustic Stimulation↗
PubMed1991

Coordinating cognitive information: task effects and individual differences in integrating information from several sources.

In many tasks people have to coordinate the information from several sources. An example would be driving a car while listening to directions. The driver has to establish a correspondence between a visual picture and verbal instructions. This paper addresses two questions concerning information coordination. Is there an ability to coordinate information received from several sources that is different from the ability to deal with information from each source, alone? Does coordination simply involve allocating resources to deal with the component tasks, or does the act of coordination itself constitute a separate task? Four experiments examined the coordination of a verbal component task with a visual-spatial and with an auditory component task. The results showed that the ability to coordinate perceptual and verbal information is separate from the ability to deal with either perceptual or verbal information, alone. A simple resource sharing model was not adequate in explaining how coordination occurred. We relate our results to a model in which perceptual reasoning occurs independently of verbal processing, but transforming perceptual information into a propositional form is affected by concurrent verbal processing.

Adult↗
PubMed1990

Startle-inducing acoustic stimuli evoke ultrasonic vocalization in the rat.

The present study demonstrates that acoustic stimuli which induce a startle response (ASR) also evoke ultrasonic vocalization in the rat. Sound recordings were done on three consecutive days of testing during sessions of 20 acoustic stimuli each and on the following day for three minutes following 5 acoustic stimuli (nonstimulus condition). Startle-inducing stimuli evoked continuous ultrasonic calling which was maintained throughout testing. Immediately following each acoustic stimulus, however, vocalization was interrupted by a period of silence (gap). The mean duration of sounds was reduced and the interpulse interval tended to increase during acoustic stimulation as compared to the nonstimulus condition. It is concluded that startle-eliciting stimuli induce a state of fear in the rat and that the acoustic-startle-elicited ultrasonic vocalization may provide a novel model in the study of anxiety.

Animals↗
PubMed1984

Properties of spatial receptive fields in the central nucleus of the cat inferior colliculus. II. Stimulus intensity effects.

Single units in the central nucleus of the inferior colliculus (ICC) of barbiturate-anaesthetized cats were studied using pure-tone, best-frequency stimulation presented in the free field. At low stimulus intensities almost all neurones responded most strongly to stimuli positioned along the acoustical axis of the pinna contralateral to the recording electrode and there was little or no response to stimuli positioned in the ipsilateral hemifield. Four major classes of spatial response were distinguished when tones of moderate to high intensity were used. The simplest response (24% of the sample) to increasing intensity consisted of a monotonic increase in discharge level at all effective speaker positions and an expansion of the area of space from which a stimulus influenced the response (receptive field). A second class (21%) of units had a nonmonotonic increase in discharge level and an expanding receptive field with increasing intensity. Neither of these classes showed evidence of influence from the ipsilateral ear. The third class (26%) developed, at higher intensities, a second excitatory response region in the ipsilateral hemifield. The fourth class (20%) had receptive fields with fixed medial borders, irrespective of intensity. The third and fourth classes of units were thought to be binaurally influenced and to be sensitive to interaural phase and intensity differences, respectively.

Animals↗
PubMed1985

The influence of moderate-intensity noise on the compound action potential evoked by tone bursts in the guinea pig, Cavia porcellus.

Noise-induced changes in the compound action potential (CAP) evoked by tone bursts in the frequency range 0.5-24 kHz were studied in 15 pigmented guinea pigs by means of chronically implanted electrodes positioned near the round window. The animals were exposed for 120 h to continuous pink noise at the intensities 80, 90 and 100 dB SPL. During the exposure period, all the animals exhibited an exponential rise in CAP threshold, leveling out after 24-72 h (asymptotic threshold shift, ATS). The largest threshold shifts were recorded during exposure to 100 dB SPL, for frequencies in the range 8-12 kHz. In the recovery phase, after the end of noise exposure, the threshold to tones at all frequencies tested fell exponentially, reaching the original level in about 72 h in all cases.

Animals↗
PubMed1985

Evoked acoustic emissions and cochlear microphonics in the mustache bat, Pteronotus parnellii.

In the echolocating bat, Pteronotus parnellii, otoacoustic responses at a frequency of 62 kHz are measurable in the external ear canal during continuous and after transient acoustic stimulation. These responses are interpreted to represent emissions from the cochlea. They can reach an amplitude as large as 70 dB SPL and occur in the frequency range most important for echolocation, namely on the average about 700 Hz above the constant frequency component of the orientation calls. A sharp maximum of the amplitude of cochlear microphonic potentials at about 62 kHz could be correlated with the emission frequency. In one bat an evoked otoacoustic response changed to a spontaneous otoacoustic emission. The frequency and amplitude of the evoked otoacoustic responses reversibly decreased after exposure for 1 min to continuous sounds of more than 85 dB SPL with frequencies of about 2.5-7.5 kHz above the emission frequency. Similar effects occurred during anaesthesia or cooling. A possible relation between the existence of otoacoustic emissions and morphological specializations of the cochlea is discussed.

Acoustic Impedance Tests↗
PubMed1987

Frequency and time domain comparison of low-frequency auditory fiber responses in two anuran amphibians.

A comparative study of the phase-locked response of auditory nerve fibers was performed in two frog species, Eleutherodactylus coqui and Bombina orientalis. From the tuning characteristics and phase response of single auditory nerve fibers to low frequency tones (0.08-1.0 kHz) we attempt to deduce the mechanics of the auditory organ responsible for low-frequency hearing in the frog, the amphibian papilla (a.p.). The phase-locked responses of auditory nerve fibers in B. orientalis were essentially identical to those from cells with similar CFs in E. coqui, despite the presence of a conspicuous caudal extension of the a.p. in E. coqui (an apparently derived morphology), a feature completely absent in B. orientalis. The fine structure of the frequency-dependent phase behavior was examined in both species with a residual phase analysis. The most significant non-linear phase behavior was confined to neurons with CFs less than 0.3 kHz. The intensity dependence of the phase response in E. coqui revealed that the preferred firing phase of an auditory nerve fiber depends upon the relation of test frequency (TF) and CF of the neuron examined. For TFs greater than CF there was a progressive phase lag as stimulus level was increased; the inverse was true for TFs less than CF. Click latencies measured in E. coqui were inversely related to CF and were similar though systematically shorter than the response latencies estimated from the phase-frequency functions. The click response was similar to that documented in other species, showing a significant level dependence and the presence of multiple peaks, with the time between peaks related to the period of the neuron's CF. A 'neurogram' was compiled for a.p. fiber responses in both species in response to several pure tones. Based on the known tonotopy of the a.p. this measure reflects the phase response of the a.p. over the extent of its length. The population phase response in anurans is quite similar to that obtained from mammalian auditory nerve fibers for the same range of test frequencies (0.08-1.0 kHz). The similarity between the responses of auditory fibers in these two anuran species suggests the micromechanics of the a.p. rostral to the tectorial curtain is similar in both species and that it is the likely site for the origin of the CF-dependent time delays.

Acoustic Stimulation↗
PubMed1987

Postnatal development of auditory nerve and cochlear nucleus neuronal responses in kittens.

Neurons located within the auditory periphery of kittens (i.e., primary auditory nerve fibers and neurons of the cochlear nucleus (CN) exhibit similar response properties throughout the early stages of postnatal development. Neural thresholds to acoustic stimuli are uniformly high, spontaneous and acoustically-evoked discharge rates are low, input/output slopes are shallow, and temporal discharge patterns are markedly immature. Phase-locking abilities are poor in developing mammals and all neurons exhibit broad bandpass tuning curves, with center frequencies clustering near 1.5 kHz. Throughout the first week, response thresholds, maximum discharge rates, rate-intensity slopes, dynamic ranges and other response indices remain essentially unchanged. Thereafter, between the 7th and 20th postnatal days, peripheral auditory development proceeds rapidly, such that thresholds, tuning properties, temporal discharge patterns, and input/output functions achieve maturity. The role of synaptogenesis in the development of adult response properties has been studied through microionophoresis of neuroactive molecules onto the surface of neurons in the caudal divisions of the cochlear nuclei of developing kittens. Results of preliminary experiments suggest that inhibitory postsynaptic receptor function precedes intrinsic excitatory neurotransmission. Furthermore, during the first two weeks of postnatal development in kittens, GABA microionophoresis onto immature caudal CN neurons, exhibiting sustained responses to acoustic stimuli, converts response patterns to the onset type in the majority of neurons encountered.

Action Potentials↗
PubMedDate not supplied

P300 from normals and adult children of alcoholics.

The P300 event-related brain potential (ERP) was obtained from 24 pairs of undergraduate male subjects. One member of each pair reported having a father who was alcoholic (FH+), the other reported no alcoholic family member (FH-). Pairs were matched on height, weight, academic performance, and personal drinking history. Three auditory task situations were employed which manipulated stimulus discrimination difficulty. All tasks employed 20% target and 80% standard tones randomly presented with the subjects required to move their index finger whenever a target tone was detected. No differences in P300 amplitude or latency were obtained between the groups. FH+ subjects tended to demonstrate decreased amplitudes with increased amounts of reported alcohol consumption but only for the most difficult task. The results of the present study suggest that the relationship between the P300 and the heritability for alcoholism is not yet clear and may be modulated by differences in task requirements, subject populations, and personal drinking history.

Adolescent↗
PubMed2004

Sound frequency representation in cat auditory cortex.

Using the intrinsic signal optical recording technique, we reconstructed the two-dimensional pattern of stimulus-evoked neuronal activities in the auditory cortex of anesthetized and paralyzed cats. The average magnitude of intrinsic signal in response to a pure tone stimulus increased steadily as the sound pressure level increased. A detailed analysis demonstrated that the evoked signals at early frames were scaled by the sound pressure level, which in turn indicated the presence of a minimum level of sound pressure beyond which stimulus-related intrinsic signal can be generated. Intrinsic signals evoked significantly by pure tone stimuli of different frequencies were localized and arranged in an orderly manner in the middle ectosylvian gyrus, which indicates that the primary auditory field (AI) is tonotopically organized. The arrangement of optimal frequencies obtained from optical recordings of the same auditory cortex, which were conducted on different days, was highly reproducible. Furthermore, other auditory fields surrounding AI in the recorded area were allocated based on the observed tonotopicity. We also conducted unit recordings on the cats used for optical recording with the same set of acoustic stimuli. The gross feature of the arrangement of optimal frequencies determined by unit recordings agreed with the tonotopic arrangement determined by the optical recording, although the precise agreement was not obtained.

Acoustic Stimulation↗
PubMed2006

Increased event-related theta activity as a psychophysiological marker of comorbidity in children with tics and attention-deficit/hyperactivity disorders.

OBJECTIVE: The question as to whether coexisting tic disorder (TD) and attention-deficit/hyperactivity disorder (ADHD) in children represent a combination of two independent pathologies, a separate nosologic entity manifested by both tics and hyperactivity or a phenotype subgroup of one of the two major clinical forms has received increasing attention. The aim of the present study was to classify the TD+ADHD comorbidity in the neurocognitive domain and to elucidate the neurophysiological background of TD+ADHD coexistence by analyzing event-related electroencephalographic (EEG) oscillations in the theta (3-7.5 Hz) frequency band. METHODS: Event-related potentials were recorded at 10 electrodes in 53 children (9-13 years old) from four groups (healthy controls, TD-only, ADHD-only, and combined TD+ADHD patients), while they performed an auditory selective attention task requiring a button press to a predefined target. Event-related theta oscillations were analyzed by means of time-frequency decomposition (wavelet analysis) in two latency ranges-early (0-200 ms) and late (200-450 ms). The effects of psychopathology factors (TD and ADHD) and task variables (attended channel and stimulus task relevance) on early (ETR) and late (LTR) theta responses were evaluated statistically. Theta response measures were further correlated with psychopathology scores and spontaneous theta EEG activity. RESULTS: (1) The ETR was enhanced only in comorbid children and did not differ between the control, TD-only, and ADHD-only groups. (2) The LTR was larger in children with ADHD (ADHD-only and comorbid), but this effect was mediated by the spontaneous theta EEG activity. (3) The ETR was larger to attended stimuli at frontal-central electrodes contralateral to the side of attention, to the target stimulus type at frontal locations, and at the hemisphere contralateral to the side of the response. The functional reactivity and scalp distribution of ETRs were modulated by psychopathological factors. CONCLUSIONS: In the neurocognitive domain, the TD+ADHD comorbidity can be identified as a unique nosologic entity. Both the spontaneous theta activity and late event-related theta oscillations appear as neurophysiological markers of the ADHD condition. In children, the early event-related theta oscillations may be associated with representations of relevant target features in working memory. SIGNIFICANCE: (1) A new model is proposed according to which TD+ADHD comorbidity can be classified at different levels (from neurobiological to cognitive). (2) The functional significance of stimulus-synchronized theta oscillations in children is described for the first time.

Adolescent↗
PubMed1993

Representation of acoustic events in the primary auditory cortex.

One approach to the problem of specifying the contribution of the primary auditory cortex to auditory perception has been based on single-neuron recording techniques in animals. These experiments measure the response rates of individual neural elements to parametric variations in 1 or more stimulus dimensions. The patterns of response rates and response failures revealed by these manipulations are quantitative descriptions of the form and fidelity of the cortex's representation of those stimulus dimensions. This strategy has been used to advantage in studies of the cortical representation of the spectral content of auditory events, the spatial location of a sound, and the time structure of sounds. The data constitute new links between neural coding and behavioral performance in normal and impaired listeners.

Animals↗