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PubMed1988

Auditory long latency event-related potentials in Alzheimer's disease and multi-infarct dementia.

An auditory discrimination paradigm was employed to elicit event-related brain potentials in 13 patients with Alzheimer's disease and 14 patients with multi-infarct dementia. The P300 latency was significantly prolonged in 12 patients with dementia compared with age-matched controls and showed a significant negative correlation with the score of Wechsler Adult Intelligence Scale (WAIS), especially with that of Digit Span subtest. There was no disease specificity. After physostigmine treatment, P300 latency decreased and WAIS score increased in 6 among 10 cases.

Aged↗
PubMed2003

Modulation rate discrimination for unresolved components: temporal cues related to fine structure and envelope.

The present study investigated the hypothesis that the cues for modulation rate discrimination for unresolved spectral components differ as a function of the spectral region occupied by the stimuli. Specifically, it was hypothesized that when components occupy relatively low spectral regions, phase locking both to the fine structure and to the envelope are useful cues. However, as the spectral region occupied by the components increases, phase locking to the fine structure becomes less robust, whereas phase locking to the envelope remains as a potentially strong cue. Observers were asked to detect a decrease in modulation rate for carrier frequencies between 1500 and 6000 Hz. Both amplitude-modulated (AM) and quasifrequency-modulated (QFM) tones were used in order to produce stimuli having strong and weak envelope cues, respectively. Although there were marked individual differences, the results showed an interaction between modulation type and spectral region, with AM and QFM performance being relatively similar at low spectral region, but with QFM showing a steeper reduction in performance as the spectral region of the carrier frequency increased. Overall, the data are consistent with an interpretation that pitch perception for unresolved components depends upon both fine structure and envelope cues, and that the relative importance of these cues depends upon the spectral region occupied by the stimuli.

Adult↗
PubMed2004

Are nonlinguistic functions in "Broca's area" prerequisites for language acquisition? FMRI findings from an ontogenetic viewpoint.

There is incomplete consensus on the anatomical demarcation of Broca's area in the left inferior frontal gyrus and its functional characterization remains a matter of debate. Exclusive syntactic specialization has been proposed, but is overall inconsistent with the neuroimaging literature. We examined three functional MRI (fMRI) datasets on lexicosemantic decision, tone discrimination, and visuomotor coordination for potential overlap of activation. A single site of convergent activation across all three paradigms was found in the left inferior frontal lobe (area 44/45). This result is discussed in the context of animal and human studies showing inferior frontal participation in visuomotor and audiomotor functions as well as working memory. We propose that Broca's area involvement in lexical semantics and syntax emerges from these nonlinguistic functions, which are prerequisites for language acquisition.

Adult↗
PubMed1993

The influence of light drowsiness on the latency and amplitude of P300.

Light drowsiness affected the P300 obtained with a standard auditory oddball paradigm. A simple two-tone discrimination paradigm was used. The frequent nontarget stimuli were 1000 Hz pure tones and the infrequent target stimuli were 2000 Hz pure tones. The subjects were required to press a button whenever infrequent target tones were presented. With light drowsiness, P300 increased in latency and decreased in amplitude, but the counts of infrequent tones remained correct nevertheless. It was concluded that electrophysiological brain function differs in the light drowsy and awake states. In studies on P300, it is essential to rule out light drowsiness to obtain valid P300 amplitudes and latencies.

Adult↗
PubMed2004

An fMRI investigation of speech and tone segmentation.

Recent research strongly indicates that phonological tasks activate a subregion of the inferior frontal gyrus. The purpose of the present fMRI study was to investigate the extent to which activation of this region during phonological processing is due to speech processes per se such as articulatory recoding or to other cognitive task demands such as working memory. Thus, we compared activation patterns during segmentation of speech and tone sequences to a tone discrimination task. In particular, participants performed same/different judgments on pairs of words, pseudowords, and tone sequences that required segmentation of a continuous acoustic signal as well as tone pairs that did not require segmentation. Accuracy and reaction time data showed that speech and tone sequence segmentation conditions patterned more similarly to each other than to tone discrimination pairs. Analyses of group data revealed strong activation of the region at the border of the left inferior and middle frontal gyrus for all three segmentation conditions compared to tone discrimination, but no consistent differences were observed when word and pseudoword segmentation were directly contrasted. Analyses of individual subjects indicated that a large number of participants activated a small area of the middle frontal gyrus during the speech conditions compared to the sequences. These results suggest that a significant portion of active frontal areas is recruited for extracting acoustic information and maintaining it in memory for decision. However, some regions at the border of the inferior/middle frontal gyrus may be unique to speech segmentation.

Adult↗
PubMed2006

Change detection and difference detection of tone duration discrimination.

An event-related potential called mismatch negativity is known to exhibit physiological evidence of sensory memory. Mismatch negativity is believed to represent complicated neuronal mechanisms in a variety of animals and in humans. We employed the auditory oddball paradigm varying sound durations and observed two types of duration mismatch negativity in anesthetized guinea pigs. One was a duration mismatch negativity whose increase in peak amplitude occurred immediately after onset of the stimulus difference in a decrement oddball paradigm. The other exhibited a peak amplitude increase closer to the offset of the longer stimulus in an increment oddball paradigm. These results demonstrated a mechanism to percept the difference of duration change and revealed the importance of the end of a stimulus for this perception.

Acoustic Stimulation↗
PubMed2004

Within- and between-channel gap detection in the human auditory cortex.

We examined the neural correlates associated with a short gap between two identical pure tones (within-channel) and between two different tones (between-channel) in an odd-ball paradigm. Gap durations were selected such that a gap between identical tones was as discriminable as a gap between two different tones. Spatio-temporal dipole source modeling of electrophysiological data revealed a significant difference between standard and deviant gap stimuli, with mismatch negativity responses that were comparable in amplitude and latency for within- and between-channel conditions. Therefore, the ability to automatically register discontinuity (i.e., gap) within and between channels is comparable despite significant differences in gap size. The dipole source modeling suggests that both within- and between-gap signals are represented in or near the primary auditory cortex.

Acoustic Stimulation↗
PubMed2004

An investigation of the role of auditory cortex in sound localization using muscimol-releasing Elvax.

Lesion studies suggest that primary auditory cortex (A1) is required for accurate sound localization by carnivores and primates. In order to elucidate further its role in spatial hearing, we examined the behavioural consequences of reversibly inactivating ferret A1 over long periods, using Elvax implants releasing the GABA(A) receptor agonist muscimol. Sub-dural polymer placements were shown to deliver relatively constant levels of muscimol to underlying cortex for >5 months. The measured diffusion of muscimol beneath and around the implant was limited to 1 mm. Cortical silencing was assessed electrophysiologically in both auditory and visual cortices. This exhibited rapid onset and was reversed within a few hours of implant removal. Inactivation of cortical neurons extended to all layers for implants lasting up to 6 weeks and throughout at least layers I-IV for longer placements, whereas thalamic activity in layer IV appeared to be unaffected. Blockade of cortical neurons in the deeper layers was restricted to < or = 500 microm from the edge of the implant, but was usually more widespread in the superficial layers. In contrast, drug-free Elvax implants had little discernible effect on the responses of the underlying cortical neurons. Bilateral implants of muscimol-Elvax over A1 produced significant deficits in the localization of brief sounds in horizontal space and particularly a reduced ability to discriminate between anterior and posterior sound sources. The performance of these ferrets gradually improved over the period in which the Elvax was in place and attained that of control animals following its removal. Although similar in nature, these deficits were less pronounced than those caused by cortical lesions and suggest a specific role for A1 in resolving the spatial ambiguities inherent in auditory localization cues.

Acoustic Stimulation↗
PubMed2005

Examining rhythm and melody processing in young children using FMRI.

While it is often reported that musical experience can have positive effects on cognitive development in young children, the neural basis of such potential effects remains relatively unexplored. Employing functional magnetic resonance imaging (fMRI) for such research presents as many challenges as possibilities, not least of which is the fact that young children can find it difficult to remain still and attentive for long periods of time. Here we describe an fMRI scanning protocol designed specifically for young children using short scanning runs, a sparse temporal sampling data acquisition technique, simple rhythmic and melodic discrimination tasks with a button-press response, and a child-oriented preparation session. Children were recruited as part of a large-scale longitudinal study examining the effects of musical training on cognitive development and the structure and function of the growing brain. Results from an initial analysis of 33 children and from the first five children to be re-scanned after musical training indicate that our scanning protocol is successful and that activation differences can be detected both between conditions and over time.

Child↗
PubMed1986

Infants' attentional responses to frequency modulated sweeps.

In 3 experiments, the attentional responses of 4-month-old infants to frequency-modulated (FM) sweeps corresponding to the frequency range of adult-to-infant and adult-to-adult intonation patterns were assessed. In Experiment 1, infants were observed to discriminate "exaggerated" (i.e., adult-to-infant) FM sweeps from "normal" (i.e., adult-to-adult) FM sweeps in a habituation-dishabituation paradigm but did not selectively attend to one over the other. In Experiment 2, where the same stimuli were used in a paired-comparison paradigm, again no differential attention was observed. In Experiment 3, the most exaggerated sweep was paired against a continuous, monotonic pure tone, but again no difference in salience was observed. These data suggest that the extent of modulation or intonation of an auditory stimulus per se does not constitute a salient cue for infants' attention to sound.

Arousal↗
PubMed1985

Extension of a temporal model of frequency discrimination: intensity effects in normal and hearing-impaired listeners.

The effects of intensity on the difference limen for frequency (DLF) in normal-hearing and in hearing-impaired listeners are incorporated into the temporal model of frequency discrimination proposed by Goldstein and Srulovicz [Psychophysics and Physiology of Hearing, edited by E. F. Evans and J.P. Wilson (Academic, New York, 1977)]. A simple extension of the temporal mode, which includes the dependence of phase locking on intensity, is sufficient to predict the effects of intensity on the DLF in normal-hearing listeners. To account for elevated DLFs in hearing-impaired listeners the impairment is modeled as a reduction in the synchrony of the discharge from VIIIth-nerve fibers that innervate the region of hearing loss. Constraints on the optimal processor and the validity of the temporal model at high frequencies are discussed.

Hearing Loss↗
PubMed1987

Identification of intonation contours by normally hearing and profoundly hearing-impaired listeners.

Fundamental frequency (F0) information extracted from low-pass-filtered speech and aurally presented as frequency-modulated sinusoids can greatly improve speechreading performance [Grant et al., J. Acoust. Soc. Am. 77, 671-677 (1985)]. To use this source of information, listeners must be able to detect the presence or absence of F0 (i.e., voicing), discriminate changes in frequency, and make judgments about the linguistic meaning of perceived variations in F0. In the present study, normally hearing and hearing-impaired subjects were required to locate the stressed peak of an intonation contour according to the extent of frequency transition at the primary peak. The results showed that listeners with profound hearing impairments required frequency transitions that were 1.5-6 times greater than those required by normally hearing subjects. These results were consistent with the subjects' identification performance for intonation and stress patterns in natural speech, and suggest that natural variations in F0 may be too small for some impaired listeners to perceive and follow accurately.

Auditory Threshold↗
PubMed1994

Event-related potentials to an "oddball" auditory paradigm in children with learning disabilities with or without attention deficit hyperactivity disorder.

Event Related Potentials (ERP) were recorded during a two-tone discrimination task in 18 children with Learning Disabilities (LD) and 36 children with Learning Disabilities and Attention Deficit Hyperactivity Disorder (LD-ADHD). Twenty-seven normal children served as a control group. P3 wave amplitude was significantly smaller in the LD and LD-ADHD groups compared with normal children. There was no difference between the LD and LD-ADHD groups. It is suggested that the smaller P3 amplitude in children with LD-ADHD syndromes reflects cognitive and processing difficulties, which frequently coexist with ADHD in these children and is not specifically related to an attention deficit.

Attention Deficit Disorder with Hyperactivity↗
PubMedDate not supplied

Event-related potential measurement of deficits in information processing following moderate to severe closed head injury.

Event-related potentials may offer more precision than behavioural measures for understanding the extent and timing of information processing difficulties that follow closed head injury (CHI). Behavioural tests consistently indicate a general reduction in cognitive function but lack adequate diagnostic or prognostic function. This study compares a group of seven CHI patients, in which time since injury varied between 1 and 5 years following injury, with 10 matched controls on a three-tone discrimination task. Abnormality in the processing of tones as early as 200 ms following their onset, as measured by the P2 and N2 components of the event-related potential, indicated a general difficulty with tone discrimination. This abnormality was obtained despite differing damage profiles over patients and is likely to be due to the diffuse aspects of damage normal in CHI. These results also indicate that functional deficits in CHI patients can extend up to 5 years or more. A correlation between P2/N2 amplitudes and time since injury, however, suggests that both these components normalize with the passage of time and offers the prospect of a sensitive, non-behavioural measure of recovery in cognitive processing.

Adolescent↗
PubMed2005

A case of amusia caused by the infarction of anterior portion of bilateral temporal lobes.

It remains an unsettled question which brain regions participate in music perception. During singing a familiar song, the retrieval from long-term memory is necessary, but the mechanism of that retrieval is still unclear. We carried out a detailed examination of musical ability in a patient with amusia and control subjects and identified the lesion sites of our patient using MRI. Compared with controls, the patient manifested the following impairments in music perception: (i) the recognition and discrimination of familiar melodies; (ii) the discrimination of unfamiliar phrases; (iii) the discrimination of isolated chords. During singing familiar nursery songs, the patient showed the replacement of one phrase of the melody. In MRI, the patient had old infarction in the anterior portion of the temporal lobes bilaterally. In conclusion, the anterior temporal lobes participate in the perception and expression of music. During singing, the song is retrieved from long-term memory by a unit of one phrase. The dysfunction of that retrieval caused the replacement of the succeeding phrases of the original with the wrong tune, and we named this phenomenon paramelodia.

Aged↗
PubMed1997

On the role of the olivocochlear bundle in hearing: 16 case studies.

Earlier we presented data (Scharf et al. (1994) Hear. Res. 75, 11-26) from a young patient (S.B.) who had undergone a vestibular neurotomy, during which the olivocochlear bundle (OCB) was severed. Those data are complemented by measurements on 15 other patients-some like S.B. with normal audiometric thresholds, none with a loss greater than 35 dB at experimental frequencies. Comparisons of performance for the same ear before and after surgery or between the operated and healthy ears do not provide evidence that the lack of OCB input impairs the following psychoacoustical functions: (1) detection of tonal signals, (2) intensity discrimination, (3) frequency selectivity, (4) loudness adaptation, (5) frequency discrimination within a tonal series, (6) in-head lateralization. Data on single-tone frequency discrimination are equivocal. These mostly negative results apply to listening both in the quiet and, where relevant, in noise. The only clear change in hearing after a vestibular neurotomy is that most patients detect signals at unexpected frequencies better than before. This change suggests an impaired ability to focus attention in the frequency domain. Although limited in scope, our finding that human hearing without OCB input is essentially normal agrees with much of the relevant literature on animal behavior and with the patients' self-reports.

Acoustic Stimulation↗
PubMed2003

Detection and direction-discrimination of diotic and dichotic ramp modulations in amplitude and phase.

When the source of a tone moves with respect to a listener's ears, dichotic (or interaural) phase and amplitude modulations (PM and AM) are produced. Two experiments investigated the psychophysical characteristics of dichotic linear ramp modulations in phase and amplitude, and compared them with the psychophysics of diotic PM and AM. In experiment 1, subjects were substantially more sensitive to dichotic PM than diotic PM, but AM sensitivity was equivalent in the dichotic and diotic conditions. Thresholds for discriminating modulation direction were smaller than detection thresholds for dichotic AM, and both diotic AM and PM. Dichotic PM discrimination thresholds were similar to detection thresholds. In experiment 2, the effects of ramp duration were examined. Sensitivity to dichotic AM and PM, and diotic AM increased as duration was increased from 20 ms to 200 ms. The functions relating sensitivity to ramp duration differed across the stimuli; sensitivity to dichotic PM increased more rapidly than sensitivity to dichotic or diotic AM. This was also reflected in shorter time-constants and minimum integration times for dichotic PM detection. These findings support the hypothesis that the analysis of dichotic PM and AM rely on separate mechanisms.

Adult↗
PubMed1994

[New aspects of hearing aid fitting].

Improved methods to diagnose a hearing loss and the enormous progress in the development of digital and programmable hearing aids have been helpful in promoting the social integration of patients, even of those affected by a profound deafness. Besides the hearing loss, recruitment effects and alteration of sound can also be compensated by the new hearing aids. However, one precondition is that the hearing aid fitting is carried out professionally, with plenty of time, and including the new hearing aid fitting methods. The new techniques developed in our hospital to optimize hearing aid fitting are pointed out. Fitting should start by considering what kind of ear mould and what kind of different modifications are to be taken. In a great number of patients we were able to verify that venting combined with the insertion of a Bakke- or Libby-horn increases not only the subjective acceptance of the hearing aid, but also significantly improves speech discrimination, particularly under background noise. The preselection of the hearing device and precise adjustment are based on the hearing loss in different frequencies, involving the principle that the frequency response of the hearing aid and the audiogram mirror each other accordingly, whereas the gain of the hearing aid can not be recognised exactly from the audiogram. In contrast to the POGO- and the NAL-method, we recommend a greater amplification, especially in the higher range of frequency. Today, the in-situ-measurement with a probe microphone is considered to be the method of choice for accurate frequency adjustment.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗