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PubMed2004

Midlatency auditory event-related potentials in mice: comparison to midlatency auditory ERPs in humans.

Midlatency event-related potentials (ERPs) reflect early stages in processing of modality specific information. In humans, the auditory midlatency ERPs most investigated are the P1, N1 and P2. Abnormalities of these ERPs in neuropsychiatric disorders such as schizophrenia point to deficits in information processing at early stages. Investigations of corresponding ERPs in mice might thus permit to elucidate the molecular biology of such abnormalities. We conducted studies in mice and humans in order to establish the correspondence of midlatency ERPs in mice to the human P1, N1 and P2. We investigated their so-called recovery function-i.e. their systematic amplitude changes as a function of varying stimulus onset asynchrony (SOA). Furthermore, we explored effects of specific genetic alterations (ERK1 gene deletion Gdi1 gene deletion) on this measure. In mice, P1-like activity showed a significant recovery not present in human data. In contrast, N1-like and P2-like activity in mice demonstrated similar recovery functions as the corresponding ERPs in human subjects and could be best fitted by the same function. In addition, ERK1 gene knockout mice showed a significantly different N1 recovery function compared to wild-type mice, possibly related to enhanced memory functions in these mice. Our results indicate that midlatency ERPs in mice share some, but not all, characteristics with the human P1, N1 and P2. As in humans, N1 recovery may provide an assessment of auditory sensory memory function. Investigations of these ERPs in mice may thus permit to elucidate the abnormalities underlying deficient generation of these ERPs in neuropsychiatric disorders.

Acoustic Stimulation↗
PubMed2003

Binaural interaction of bone-conducted auditory brainstem responses in children with congenital atresia of the external auditory canal.

Bilateral bone-conducted auditory brainstem responses (BC-ABRs) were recorded in children with atresia of the external auditory canal bilaterally (AECB) in order to compare the response characteristics to normal hearing adults. The binaural interaction component (BIC) of the ABR occurs when the sum of the monaural-evoked ABR amplitudes are different in amplitude when compared to the binaural-evoked ABR amplitude. Previous electrophysiological work from our lab has shown that children with AECB lateralize bone-conducted (BC) sound. Furthermore, we have found in normal-hearing adults that BICs exist using BC clicks. In adults, BC-BIC occurred in the latency region corresponding to waves IV-VI, whereas for children with AECB corresponding peak latencies occurred earlier. Same as normal-hearing adults, BC-ABR IV-V complex peak amplitudes for sum of the BC-monaural right and BC-monaural left ears were different from binaural response amplitude. Individual peak latencies were similar in children with AECB when compared to normal-hearing adults except for shorter latencies for BIC. These results indicate that: (1) BC-BI is present in children with AECB as well as normal-hearing adults; (2) the gross response properties of BIC are similar in children with AECB and normal-hearing adults; (3) fitting of a bilateral BC hearing aid might be a feasible method to optimize binaural hearing and sound lateralization.

Adolescent↗
PubMed1983

Auditory spatial alternation transforms auditory time.

Recent research has shown that a sequence of auditory events that is alternated between the ears is stretched out in auditory memory, as compared with nonalternating sequences. Although the stimulus-onset asynchronies (SOAs) of the interaural and monaural sequences were the same, the perceptual-onset asynchronies (POAs) differed by 24 msec. Because this result was only established for a restricted range of SOAs (125-250 msec), the present study tested a much larger range (40-2,130 msec). It turned out that the POA difference of 25 msec remained invariant over this whole range. Furthermore it was investigated how the angle of alternation affected the POA difference. It was found that (a) this difference increased linearly with increasing angular separation, and (b) the effects of SOA and angular separation on the POA difference were additive. The merits of six different attention-switching models were inspected to explain these results, but none of the models could describe the effects satisfactorily. We offer a new model, the space-time network, that copes not only with the present results but also explains several other studies reported in the literature.

Attention↗
PubMed2003

Using auditory streaming to reduce disruption to serial memory by extraneous auditory warnings.

Three experiments were conducted to examine the effects of extraneous speech warnings (i.e., low-priority warnings initiated during high-priority tasks) on cognitive performance and whether organizing the auditory warnings into streams can attenuate any disruption. Experiment 1 demonstrated that a variety of speech warnings can be separated into perceptually distinct streams by allocating them to discrete spatial locations. Experiment 2 showed that increasing the rate of presentation of the warnings to promote streaming decreased clarity ratings but increased perceived urgency ratings. Experiment 3 demonstrated that the disruption to serial memory for navigational information by extraneous speech warnings could be attenuated by streaming. Results are interpreted in light of previous research, and practical implications for auditory warning design are discussed.

Adult↗
PubMed1999

Slope analysis of Auditory Brainstem Responses in children at risk of central auditory processing disorders.

The method of slope vectors was used to quantify Auditory Brainstem Responses (ABR) obtained from nine normal children and nine children at risk for central auditory processing disorders (CAPD) with language impairment, for monaural and binaural stimulation conditions. Slopes thus obtained were subjected to K-Means Cluster Analysis. Distinction between the two groups was obtained only for binaural stimulation conditions, wherein all normal children were grouped under cluster 1 with higher slope values and 6 out of 9 CAPD children were grouped under cluster 2 with lower slopes. The results suggest that there may be several subcategories among children who are found to be at risk for CAPD. One of the subcategories may comprise children who exhibit poor ABR morphology, especially during binaural stimulation conditions, which could be due to binaural interference.

Adolescent↗
PubMed2004

Auditory stream segregation in monkey auditory cortex: effects of frequency separation, presentation rate, and tone duration.

Auditory stream segregation refers to the organization of sequential sounds into "perceptual streams" reflecting individual environmental sound sources. In the present study, sequences of alternating high and low tones, "...ABAB...," similar to those used in psychoacoustic experiments on stream segregation, were presented to awake monkeys while neural activity was recorded in primary auditory cortex (A1). Tone frequency separation (AF), tone presentation rate (PR), and tone duration (TD) were systematically varied to examine whether neural responses correlate with effects of these variables on perceptual stream segregation. "A" tones were fixed at the best frequency of the recording site, while "B" tones were displaced in frequency from "A" tones by an amount = delta F. As PR increased, "B" tone responses decreased in amplitude to a greater extent than "A" tone responses, yielding neural response patterns dominated by "A" tone responses occurring at half the alternation rate. Increasing TD facilitated the differential attenuation of "B" tone responses. These findings parallel psychoacoustic data and suggest a physiological model of stream segregation whereby increasing delta F, PR, or TD enhances spatial differentiation of "A" tone and "B" tone responses along the tonotopic map in A1.

Acoustic Stimulation↗
PubMed2006

Modeling auditory-nerve responses for high sound pressure levels in the normal and impaired auditory periphery.

This paper presents a computational model to simulate normal and impaired auditory-nerve (AN) fiber responses in cats. The model responses match physiological data over a wider dynamic range than previous auditory models. This is achieved by providing two modes of basilar membrane excitation to the inner hair cell (IHC) rather than one. The two modes are generated by two parallel filters, component 1 (C1) and component 2 (C2), and the outputs are subsequently transduced by two separate functions. The responses are then added and passed through the IHC low-pass filter followed by the IHC-AN synapse model and discharge generator. The C1 filter is a narrow-band, chirp filter with the gain and bandwidth controlled by a nonlinear feed-forward control path. This filter is responsible for low and moderate level responses. A linear, static, and broadly tuned C2 filter followed by a nonlinear, inverted and nonrectifying C2 transduction function is critical for producing transition region and high-level effects. Consistent with Kiang's two-factor cancellation hypothesis, the interaction between the two paths produces effects such as the C1/C2 transition and peak splitting in the period histogram. The model responses are consistent with a wide range of physiological data from both normal and impaired ears for stimuli presented at levels spanning the dynamic range of hearing.

Acoustic Stimulation↗
PubMed1996

Validity of the Auditory Continuous Performance Test in differentiating central processing auditory disorders with and without ADHD.

The use of continuous performance tasks has been examined as a potential measure for clinical/laboratory identification of Attention-deficit/hyperactivity disorder. The present study compared the performance of 30 children, 26 boys and 4 girls ranging in age from 9-0 to 12-11, with central auditory processing disorders (CAPD) who did not meet criteria for coexisting ADHD with the performance of children with CAPD coexisting with ADHD (CAPD/ADHD) on the Auditory Continuous Performance Test (ACPT). In interpreting the results, the variability as well as the actual counts for correct responses and total errors were considered. Results indicated limited potential for the use of the ACPT in the differential diagnosis of ADHD. Implications of the results as well as considerations for future research are discussed.

Attention↗
PubMed2004

Brainstem auditory evoked potential monitoring during microvascular decompression for hemifacial spasm: intraoperative brainstem auditory evoked potential changes and warning values to prevent hearing loss--prospective study in a consecutive series of 84 patients.

OBJECTIVE: The nerve function of Cranial Nerve VIII is at risk during microvascular decompression for hemifacial spasm. Intraoperative monitoring of brainstem auditory evoked potentials (BAEPs) can be a useful tool to decrease the danger of hearing loss. The aim of this study was 1) to assess the side effects of surgery on hearing and describe the main intraoperative BAEP changes observed in the authors' series, and 2) to define warning values beyond which the probability of hearing impairment rises significantly. These values were calculated by correlating the (possible) postoperative hearing disturbances evaluated in terms of pure tone average with intraoperative BAEP changes (especially delay in Wave V latency). METHODS: This series included 84 consecutive patients affected with hemifacial spasm who underwent microvascular decompression during which BAEPs were monitored. During surgery, Wave I, I to V interpeak interval, latency, and amplitude of Wave V were recorded and measured. Auditory function was studied before and after surgery and expressed as a pure tone average in all patients. Then, correlations were made between hearing impairment after surgery and intraoperative BAEP changes in an attempt to define warning values. RESULTS: Seventy-four patients (88%) had no hearing loss after surgery (Group 1). Eight patients (9.5%) had hearing impairment with a decrease in pure tone average of more than 20 dB (Group 2). Two patients (2.3%) experienced a definitive and complete hearing loss on the side operated on (Group 3). Among intraoperative BAEP changes, latency of Peak V was the most frequently observed and the most significant phenomenon, especially during cerebellar retraction and the decompression step of the microvascular decompression procedure. In the group of patients without hearing loss (Group 1), the mean delay in latency of Peak V was 0.61 millisecond (standard deviation, +/-0.36 ms); in the group with hearing decrease (Group 2), the mean delay was 1.05 milliseconds (standard deviation, +/-0.64 ms); and in the group with deafness (Group 3), Wave V was abolished. CONCLUSION: From a practical standpoint, three warning values, based on delay in latency of Peak V, were established for use during surgery: an initial one at 0.4 millisecond ("watching" signal) at the safety limit; a second one at 0.6 millisecond (risk "warning" signal), which is the mean value corresponding to the group of patients without postoperative hearing loss; and an ultimate one at 1 millisecond ("critical" warning), before irreversibility. These warnings should help the surgeon to avoid or correct maneuvers that are dangerous for hearing function, which is mandatory in functional surgery.

Adult↗
PubMedDate not supplied

Central auditory tests and auditory nerve-brainstem evoked responses in multiple sclerosis.

In 43 multiple sclerosis (MS) patients and an equal number of age- and sex-matched normal controls, auditory nerve-brainstem evoked responses (ABR), audiometric tests, central auditory tests (CAT) and clinical-neurological examinations were conducted. The CAT included rapid alternating speech perception, masking level differences to tones and to words and lateralization based on interaural time and intensity differences. The results in the MS group on the ABR and each of the CAT differed significantly from those in the control group. The ABR results and the lateralization test results were each abnormal in 50% of the MS patients. The ABR, CAT and clinical examination results were all mutually correlated. These findings are probably related to the fact that the demyelination in MS induces a decrease in impulse velocity, to temporal dispersion and to desynchrony of impulses in groups of affected axons and to the fact that the ABR and the CAT tests chosen are dependent on synchronous impulse firing and on the precise timing of the arrival of impulses from each ear at some brain centre. These tests may therefore contribute to neurological and to audiological diagnosis.

Adolescent↗
PubMed1990

Auditory P3 latency and amplitude: relationships to earlier exogenous auditory events.

The purpose of the present study was to determine the relationship for latency and amplitude between exogenous auditory potentials arising at the level of cranial nerve VIII and continuing through the level of the cortex and the auditory P3 endogenous potential. Thirty-four normal hearing adults participated in the study. Binaural ABR, MLR, LCR, and P3 recordings were obtained using 2 kHz tone bursts as the stimulus. Relationships between peak latencies and amplitudes from the early, middle, and late potentials were analyzed using Pearson Product-Moment correlation procedures and multiple regression analyses. Results indicated no significant positive relationships for latency or amplitude between early, middle, or late exogenous potentials and the endogenous P3 potential. Pa of the MLR and P3 demonstrated significant latency/amplitude trading functions. The present data support the hypothesis that P3 latency and amplitude are not related to the latencies and amplitudes of the exogenous responses.

Acoustic Stimulation↗
PubMed1996

Auditory quality cues are more effective than auditory location cues in a R--no R (go--no go) differentiation: the extension of the rule to primitive mammals (American opossum, Didelphis virginiana).

Discrimination learning of instrumental responses to auditory compound stimuli was investigated in opossums using the R-no R (go-no go) differentiation. Each compound stimulus consisted of two factors: quality and location. Each correct response performed to the conditioned positive, or "safe" stimulus, was rewarded by food and never punished. Each incorrect response performed to the conditioned negative, or "warning" stimulus, was punished by an electric shock. In subsequent testing, each opossum proved to use only the quality cues to solve the task even though later testing showed them capable of using the location cues. Thus, the rule discovered in higher mammals, that the efficacy of auditory stimuli in differentiation depends on the perceptual ability of the animal as well as the type of the behavioral response with which the animal is confronted, may be extended to neurologically primitive mammals and also to a joint conditioned approach-avoidance method.

Acoustic Stimulation↗
PubMed1976

Electrophysiologic assessment of the lower portion of the auditory pathway in the human subject. A preliminary report on auditory evoked eighth nerve and brain stem potentials including their relation to the electrocochleogram.

The electrophysiologic approaches to the assessment of electrical activity of the various portions of the human auditory pathway are reviewed. A method of detection of click evoked eighth nerve and brain stem responses with the use of surface electrodes is described. Preliminary observations in the normal subject with different stimulus parameters and in patients with unilateral deafness are presented. Simultaneous recordings of the eighth nerve and brain stem responses with the cortical evoked response and with the extratympanic electrocochleogram are described. The technique of click evoked eighth nerve and brain stem potentials offers us an additional method of objective assessment of auditory function in a human subject.

Audiometry↗
PubMed2004

[Refractory recovery function of electrical auditory on the survival auditory nerve in cochlear implant recipients].

OBJECTIVE: To evaluate the cochlear implant recipient's electrical auditory temporal properties in order to estimate the maximum stimulating rate which can be reached when they adopted some speech coding strategies based on time mechanism, such as continuous interleaved sampling (CIS). METHODS: Thirty-eight Nucleus CI24 cochlear implant recipients were divided into 4 groups by etiology and history. Their survival auditory nerve fibers' refractory recovery time function was measured via neural response telemetry (NRT). Electrical pulses with the amplitude of recipient's loudest acceptable presentation were stimulated in mono-polar mode, with the width of 25 microseconds and the frequency of 80 Hz. Least-squares regression procedures were used to fit individual recovery functions with the equation A = C + K e(-t/tau), in which tau is the time constant of recovery from refractory state. Statistic analysis showed the relationship between the time constants of individuals and etiology as well as electrode position in the cochlea. RESULTS: Congenital deaf patient's recovery time constants were shorter than that of postnatal deaf groups of ototoxicity (P = 0.0056) and large vestibular aqueduct syndrome (P = 0.0349). There was no significant difference between the recovery time constants of congenital deaf patients and those of group with long history of deafness. The ANOVA of the recovery time constants of 5th, 10th, 15th electrode showed no significant statistical difference (P > 0.05). CONCLUSION: The recovery time constants are related with etiology. In mono-polar mode, the time constants of congenital deafness or subjects with short duration of deafness are shorter than those of postnatal deafness or subjects with long duration of deafness. Time constants do not vary systematically with electrode location along the implanted array. The reciprocal of individual electrode seems to be used in determining the maximum of stimulating rate of CIS strategy and as criteria of choosing the usable channels from 22 electrode bands.

Acoustic Stimulation↗
PubMed1991

Prediction of auditory nerve survival in humans using the electrical auditory brainstem response.

This investigation studied the electrical auditory brainstem response (EABR) input-output functions in three groups of patients: individuals with normal auditory neural systems; patients with acquired, profound sensorineural hearing loss; and patients with congenital, profound sensorineural hearing loss. Each input-output function was obtained in the operating room under general anesthesia and with the patient paralyzed to eliminate myogenic contamination. In contrast to the acoustically elicited ABR, the EABR waveforms were characterized by a dominant early wave corresponding in latency to wave II. This wave was much larger and often appeared at lower stimulus intensities than wave V. The results, plotted according to rate of growth for waves II and V, showed that normal subjects generally had larger, more robust early waves than either hearing impaired group. Little difference was noted in the amplitudes or rates of growth for wave V among the three groups. Based on these observations, we concluded that the EABR demonstrated differences in the way normal and impaired systems respond to electrical stimulation. In addition, the EABR may be useful in providing a qualitative prediction of neural survival into broad categories of many surviving neurons versus a marked reduction in ganglion/neuronal density.

Adolescent↗
PubMed1985

[Effect of nicotine on auditory functions in the rat, studied by electrocochleography and auditory evoked potentials of the brain stem].

The rôle of nicotine (100 micrograms/kg) on brainstem auditory evoked responses (FFP) and electrocochleography (EcoG) in rats anaesthetized with pentobarbital has been studied. Each component of FFP and EcoG was analysed in terms of its latency and amplitude. Nicotine failed to produce any significant changes in the latencies of the FFP and EcoG components. Nicotine after 30 min increases significantly the amplitude I, I', II and III, of the FFP components, and decreases no significantly IV and V components. These finding suggests the presence of muscarinic and nicotinic effect of nicotine, in the mediation of the brainstem auditory pathway.

Animals↗
PubMed1989

[Connection of the auditory cortex secondary zones with the auditory subcortical cerebral centers in the cat].

As it has been demonstrated microscopically, the corticofugal fibers in the AII and Ep zones of the auditory cortex in all the auditory subcortical centers (medial geniculate body, posterior colliculi of the tectum mesencephali and the superior olive nuclei) terminate by means of single axodendritic synapses, having an asymmetrically active zone, and mixed (by their form) synaptic vesicles. Small and middle dendrites make their postsynaptic part. A comparison has been carried out on distribution and form of synapses, completing the projection fibers from the zone of the primary acoustic responses (AI) and of the primary acoustic zone (AIV). Basing on the morphological data, concerning distribution and form of the synaptic terminals, a suggestion is made that physiological influence of each acoustic cortex zone is different for the medial geniculate body and posterior colliculi of the tectum mesencephali, but it is unitypical for the superior olive level.

Animals↗