Alterations In Auditory Processing Research Articles

Changes in Auditory Evoked Potentials Increase the Chances of Adults Having Central Auditory Processing Disorder.

Introduction Auditory evoked potentials are widely used in clinical practice to complement the assessment of central auditory processing. However, it is necessary to understand whether these potentials are highly accurate, to assist in the diagnosis of auditory processing disorder. Objective To measure the accuracy of middle and long latency auditory evoked potentials in the diagnosis of auditory processing disorder in adults. Methods This is a case-control study, formed by a control group of 30 individuals with normal auditory processing assessment, and a case group composed of 43 individuals with altered auditory processing assessment. Their sensitivities, specificities, accuracies, positive and negative predictive values for the diagnosis of alterations were measured and compared between the potentials. Results The accuracies of the middle and long latency potentials were 51% and 67%, respectively. The P1-N1-P2 and N2-P300 complexes had an accuracy of 57.5% and 58.9%, respectively. The cognitive potential P300 showed an accuracy of 55%. There was no significant result for the middle-latency potential (OR = 1.8; 95% CI: 0.6-5.4, p > 0.42) and for P300 (OR = 2.63, 95% CI: 0.85-8.43, p > 0.11). However, the result was significant for the long-latency potential (OR = 6.3; 95% CI: 2-19.6, p < 0.01). There was a significant result for the P1-N1-P2 complexes (OR = 6.76, 95% CI:1.4-32.5, p = < 0.010) and N2-P300 (OR = 3.60; 95% CI: 10.16-11.20, p < 0.039). Conclusion Individuals with altered long-latency auditory evoked potential are more likely to have auditory processing disorder and, as such, this test can be used as a complementary tool to confirm the diagnosis.

Differences in Startle and Prepulse Inhibition in Contactin-associated Protein-like 2 Knock-out Rats are Associated with Sex-specific Alterations in Brainstem Neural Activity

The contactin-associated protein-like 2 (CNTNAP2) gene encodes for the CASPR2 protein, which plays an essential role in neurodevelopment. Mutations in CNTNAP2 are associated with neurodevelopmental disorders, including autism spectrum disorder and schizophrenia. Rats with a loss of function mutation in the Cntnap2 gene show increased acoustic startle response (ASR) and decreased prepulse inhibition (PPI). The neural basis of this altered auditory processing in Cntnap2 knock-out rats is currently unknown. Auditory brainstem recordings previously revealed no differences between the genotypes. The next step is to investigate brainstem structures outside of the primary auditory pathway that mediate ASR and PPI, which are the pontine reticular nucleus (PnC) and pedunculopontine tegmentum (PPTg), respectively. Multi-unit responses from the PnC and PPTg in vivo of the same rats revealed sex-specific effects of loss of CASPR2 expression on PnC activity, but no effects on PPTg activity. Female Cntnap2−/− rats showed considerably increased PnC firing rates compared with female wildtypes, whereas the difference between the genotypes was modest in male rats. In contrast, for both females and males we found meager differences between the genotypes for PPTg firing rates and inhibition of PnC firing rates, indicating that altered firing rates of these brainstem structures are not responsible for decreased PPI in Cntnap2−/− rats. We conclude that the auditory processing changes seen in Cntnap2−/− rats are associated with, but cannot be fully explained by, differences in PnC firing rates, and that a loss of function mutation in the Cntnap2 gene has differential effects depending on sex.

Adverse effects due to changes in the composition of the intestinal microbiota as result of the administration of antibiotics during the perinatal period

Antibiotic administration commonly induces allergic reactions, dysmicrobism and microbial resistance, but long-term effects due to changes in gut microbiota composition are difficult to assess. This paper aims to identify in the literature adverse effects induced by changes in gut microbiota composition after perinatal administration of antibiotics. Antibiotic administration during pregnancy is a predisposing factor for the development of bronchial asthma, eczema, or allergic rhinitis in children, but does not support the hypothesis as being a risk factor for childhood obesity/overweight. The effect on the newborn’s microbiota of prophylactic administration of antibiotics during caesarean section is controversial. Postnatal treatments with antibiotics frequently causes intestinal dysmicrobism, the most severe form being necrotizing enterocolitis, especially among premature infants, but effects on the changes in body weight are controversial. Early administration of broad-spectrum antibiotics, particularly macrolides and cephalosporins, is strongly associated with the development of bronchial asthma at age 5 years. Recently, altered auditory processing and changes in recognition memory were described in newborn exposed to antibiotics in the absence of infection. More studies are needed to clarify the association between the type of antibiotic, the frequency, respectively period (both prenatal and intrapartum) of administration and long-term effects.

Infants exposed to antibiotics after birth have altered recognition memory responses at one month of age.

Background:Neonatal exposure to antibiotics, in the absence of infection, results in abnormal learning and memory in animals and is linked to changes in gut microbes. The relevance of early-life antibiotic exposure to brain function in humans is not known.Methods:Recognition memory was assessed at 1 month of age in 15 term-born infants exposed to antibiotics (with negative cultures) and 57 unexposed infants using event-related potentials (ERPs). Linear regression analysis, adjusting for covariates, was employed to compare groups with respect to ERP features representing early stimulus processing (P2 amplitude) and discrimination between mother and stranger voices.Results:Infants exposed to antibiotics exhibited smaller P2 amplitudes for both voice conditions (p = 0.001), with greatest reductions observed for mother’s voice in frontal and central scalp regions (p < 0.04). Infants exposed to antibiotics showed larger P2 amplitudes to stranger’s as compared to mother’s voice, a reversal of the typical response exhibited by unexposed infants. Abnormal ERP responses did not consistently correlate with increased inflammatory cytokines within the antibiotic-exposed group.Conclusion:Otherwise healthy infants exposed to antibiotics soon after birth demonstrated altered auditory processing and recognition memory responses, supporting the possibility of a microbiota-gut-brain axis in humans during early life.

Future Perspectives on the Relevance of Auditory Markers in Prodromal Parkinson's Disease.

Research on auditory processing in Parkinson's disease (PD) has recently made substantial progress. At present, evidence has been found for altered auditory processing in the clinical stage of PD. The auditory alterations in PD have been demonstrated with low-cost and non-invasive assessments that are already used in routine clinical practice. Since auditory alterations have been reported early in disease progression, it would be highly relevant to investigate whether auditory markers could be provided in the prodromal stage of PD. In addition, auditory alterations in early stage PD might be modulated by dopaminergic medication. Therefore, the aim of this review is (1) to summarize the literature on auditory processing in PD with a specific focus on the early disease stages, (2) to give future perspectives on which audiological and electrophysiological measurements could be useful in the prodromal stage of PD and (3) to assess the effect of dopaminergic medication on potential auditory markers in the prodromal stage of PD.

The Density of Perineuronal Nets Increases With Age in the Inferior Colliculus in the Fischer Brown Norway Rat

Age-related hearing loss, one of the most frequently diagnosed disabilities in industrialized countries, may result from declining levels of GABA in the aging inferior colliculus (IC). However, the mechanisms of aging and subsequent disruptions of temporal processing in elderly hearing abilities are still being investigated. Perineuronal nets (PNs) are a specialized form of the extracellular matrix and have been linked to GABAergic neurotransmission and to the regulation of structural and synaptic plasticity. We sought to determine whether the density of PNs in the IC changes with age. We combined Wisteria floribunda agglutinin (WFA) staining with immunohistochemistry to glutamic acid decarboxylase in three age groups of Fischer Brown Norway (FBN) rats. The density of PNs on GABAergic and non-GABAergic cells in the three major subdivisions of the IC was quantified. Results first demonstrate that the density of PNs in the FBN IC increase with age. The greatest increases of PN density from young to old age occurred in the central IC (67% increase) and dorsal IC (117% increase). Second, in the young IC, PNs surround non-GABAergic and GABAergic cells with the majority of PNs surrounding the former. The increase of PNs with age in the IC occurred on both non-GABAergic and GABAergic populations. The average density of PN-surrounded non-GABAergic cells increased from 84.9 PNs/mm2 in the young to 134.2 PNs/mm2 in the old. While the density of PN-surrounded GABAergic cells increased from 26 PNs/mm2 in the young to 40.6 PNs/mm2 in the old. The causality is unclear, but increases in PN density in old age may play a role in altered auditory processing in the elderly, or may lead to further changes in IC plasticity.

Mismatch Negativity Elicited by Verbal and Nonverbal Stimuli: Comparison with Potential N1.

Introduction Mismatch negativity (MMN) is a long latency auditory evoked potential, represented by a negative wave, generated after the potential N1 and visualized in a resulting wave. Objective To identify the time of occurrence of MMN after N1, elicited with verbal and nonverbal stimuli. Methods Ninety individuals aged between 18 and 56 years old participated in the study, 39 of whom were male and 51 female, with normal auditory thresholds, at least 8 years of schooling, and who did not present auditory processing complaints. All of them underwent audiologic anamnesis, visual inspection of external auditory meatus, pure tone audiometry, speech audiometry, acoustic immittance measures and the dichotic sentence identification test as a screening for alterations in auditory processing, a requirement to participate in the sample. The MMN was applied with two different stimuli, with these being da/ta (verbal) and 750 Hz and 1,000 Hz (nonverbal). Results There was a statistically significant difference between the latency values of the N1 potential and the MMN with the two stimuli, as well as between the MMN with verbal and nonverbal stimuli, and the latency of the MMN elicited with da/ta being greater than that elicited with 750 Hz and 1,000 Hz, which facilitated its visualization. Conclusion The time of occurrence of MMN after the N1 elicited with verbal stimuli was 100.4 ms and with nonverbal stimuli 85.5 ms. Thus, the marking of the MMN with verbal stimuli proved to be more distant from N1 compared with the nonverbal stimuli.

Auditory Deficits in Audiovisual Speech Perception in Adult Asperger's Syndrome: fMRI Study.

Audiovisual (AV) integration deficits have been proposed to underlie difficulties in speech perception in Asperger’s syndrome (AS). It is not known, if the AV deficits are related to alterations in sensory processing at the level of unisensory processing or at levels of conjoint multisensory processing. Functional Magnetic-resonance images (MRI) was performed in 16 adult subjects with AS and 16 healthy controls (HC) matched for age, gender, and verbal IQ as they were exposed to disyllabic AV congruent and AV incongruent nouns. A simple semantic categorization task was used to ensure subjects’ attention to the stimuli. The left auditory cortex (BA41) showed stronger activation in HC than in subjects with AS with no interaction regarding AV congruency. This suggests that alterations in auditory processing in unimodal low-level areas underlie AV speech perception deficits in AS. Whether this is signaling a difficulty in the deployment of attention remains to be demonstrated.

Developmental Effects on Auditory Neural Oscillatory Synchronization Abnormalities in Autism Spectrum Disorder.

Previous studies have found alterations in 40 Hz oscillatory activity in response to auditory stimuli in adults with Autism Spectrum Disorder (ASD). The current study sought to examine the specificity and developmental trajectory of these findings by driving the cortex to oscillate at a range of frequencies in both children and adults with and without ASD. Fifteen participants with ASD (3 female, aged 6–23 years) and 15 age-matched controls (4 female, aged 6–25 years) underwent dense-array EEG as they listened to a carrier tone amplitude-modulated by a sinusoid linearly increasing in frequency from 0–100 Hz over 2 s. EEG data were analyzed for inter-trial phase coherence (ITPC) and single-trial power (STP). Older participants with ASD displayed significantly decreased ability to phase-lock to the stimulus in the low gamma frequency range relative to their typically developing (TD) counterparts, while younger ASD and TD did not significantly differ from each other. An interaction between age and diagnosis suggested that TD and ASD also show different developmental trajectories for low gamma power; TD showed a significant decrease in low gamma power with age, while ASD did not. Regardless of age, increased low gamma STP was significantly correlated with increased clinical scores for repetitive behaviors in the ASD group, particularly insistence on sameness. This study contributes to a growing body of evidence supporting alterations in auditory processing in ASD. Older ASD participants showed more pronounced low gamma deficits than younger participants, suggesting an altered developmental trajectory for neural activity contributing to auditory processing deficits that may also be more broadly clinically relevant. Future studies are needed employing a longitudinal approach to confirm findings of this cross-sectional study.

Auditory processing disorder evaluations and cognitive profiles of children with specific learning disorder

ObjectiveThis study investigated the auditory sensory-perceptual level of specific learning disorder (SLD) and explored relationships among neuropsychological assessments for SLD, auditory processing, and short and long latencies of auditory event-related potentials (ERPs). MethodsFifteen children (7–14 years old) comprised the control group; 34 children comprised the SLD group. Audiologic assessments included tone audiometry, acoustic immittance measurements, acoustic reflex, central auditory processing, brainstem evoked response audiometry, and long latency potentials (P3 and N2). Children’s intelligence levels were assessed with 2 intelligence batteries, 1 verbal and 1 non-verbal, as well as with visuomotor skills. ResultsMultiple regression showed a significant interaction effect of APE tests and P3/N2 over Wechsler Scale performance in freedom of distractibility indexes and multiple subtests. Errors in the Bender Visual Motor Gestalt Test were predicted by lower parental education, lower performance in APE tests: dichotic digits and pediatric/synthetic sentence identification-ipsilateral, and longer P3/N2 latencies, particularly regarding integration and rotation distortions. ConclusionsChildren with altered auditory processing exhibit a specific cognitive profile, including lower verbal and spatial reasoning performance, that is sensitive to parental education level. SignificanceChildren with SLD should undergo a complete multimodal examination to identify their specific difficulties and needs.

Missing a trick: Auditory load modulates conscious awareness in audition.

In the visual domain there is considerable evidence supporting the Load Theory of Attention and Cognitive Control, which holds that conscious perception of background stimuli depends on the level of perceptual load involved in a primary task. However, literature on the applicability of this theory to the auditory domain is limited and, in many cases, inconsistent. Here we present a novel "auditory search task" that allows systematic investigation of the impact of auditory load on auditory conscious perception. An array of simultaneous, spatially separated sounds was presented to participants. On half the trials, a critical stimulus was presented concurrently with the array. Participants were asked to detect which of 2 possible targets was present in the array (primary task), and whether the critical stimulus was present or absent (secondary task). Increasing the auditory load of the primary task (raising the number of sounds in the array) consistently reduced the ability to detect the critical stimulus. This indicates that, at least in certain situations, load theory applies in the auditory domain. The implications of this finding are discussed both with respect to our understanding of typical audition and for populations with altered auditory processing. (PsycINFO Database Record

Development of the acoustic startle response in rats and its change after early acoustic trauma

Even brief acoustic trauma during the critical period of development that results in no permanent hearing threshold shift may lead to altered auditory processing in adulthood. By monitoring the acoustic startle response (ASR), we examined the development of auditory function in control rats and in rats exposed to intense noise at the 14th postnatal day (P14). First ASRs appeared on P10–P11 to intense low-frequency tones. By P14, the range of sound intensities and frequencies eliciting ASRs extended considerably, the ASR reactivity being similar at all frequencies (4–32kHz). During the subsequent two weeks, ASR amplitudes to low-frequency stimuli (4–8kHz) increased, whereas the ASRs to high-frequency tones were maintained (16kHz) or even decreased (32kHz). Compared to controls, noise exposure on P14 (125dB SPL for 8, 12, or 25min) produced transient hyper-reactivity to startle stimuli, manifested by a decrease of ASR thresholds and an increase of ASR amplitudes. ASR enhancement occurred regardless of permanent hearing loss and was more pronounced at high frequencies. The hyper-reactivity of ASRs declined by P30; the ASR amplitudes in adult exposed rats were lower than in controls. The histological control did not reveal loss of hair cells in adult exposed rats, however, the number of inner hair cell ribbon synapses was significantly decreased, especially in the high-frequency part of the cochlea. The results indicate that early acoustic trauma may result in complex changes of ASRs during development.

Dexamethasone induced changes of neural activity in the auditory cortex of rats

Previous studies have suggested that elevation of glucocorticoid level can alter auditory processing and may have relevance for auditory hallucinations. However, the neural mechanism underlying the glucocorticoid induced sensory change remains unclear. To examine the effects of glucocorticoid on the neuronal spike activities of sensory cortex, we topically applied dexamethasone (DEX), a glucocorticoid receptor agonist, to the auditory cortical surface of rats while recording single-unit extracellular spike activities in response to sound stimuli. Our major findings are: (1) a topical administration of DEX increased the cortical neural responses to pure-tone stimuli from 10 to 60min after administration, while the peak response enhancement occurred at 20–30min; (2) DEX not only markedly increased the magnitude of tone-evoked responses, but also extended the response duration and the frequency range of the neural responses; (3) the enhancement of neural responses was more salient at the higher frequency band; (4) the ratio of spontaneous firing rate between post- and pre-administration was negatively correlated with the unit's spontaneous firing rate before treatment. Our data confirm that DEX can modulate the neural activity at the cortical level and provide more information for understanding the mechanism of glucocorticoid-induced alterations in auditory processing.

Auditory Processing in Fragile X Syndrome

Fragile X syndrome (FXS) is an inherited form of intellectual disability and autism. Among other symptoms, FXS patients demonstrate abnormalities in sensory processing and communication. Clinical, behavioral, and electrophysiological studies consistently show auditory hypersensitivity in humans with FXS. Consistent with observations in humans, the Fmr1 KO mouse model of FXS also shows evidence of altered auditory processing and communication deficiencies. A well-known and commonly used phenotype in pre-clinical studies of FXS is audiogenic seizures. In addition, increased acoustic startle response is seen in the Fmr1 KO mice. In vivo electrophysiological recordings indicate hyper-excitable responses, broader frequency tuning, and abnormal spectrotemporal processing in primary auditory cortex of Fmr1 KO mice. Thus, auditory hyper-excitability is a robust, reliable, and translatable biomarker in Fmr1 KO mice. Abnormal auditory evoked responses have been used as outcome measures to test therapeutics in FXS patients. Given that similarly abnormal responses are present in Fmr1 KO mice suggests that cellular mechanisms can be addressed. Sensory cortical deficits are relatively more tractable from a mechanistic perspective than more complex social behaviors that are typically studied in autism and FXS. The focus of this review is to bring together clinical, functional, and structural studies in humans with electrophysiological and behavioral studies in mice to make the case that auditory hypersensitivity provides a unique opportunity to integrate molecular, cellular, circuit level studies with behavioral outcomes in the search for therapeutics for FXS and other autism spectrum disorders.

Auditory processing in remitted major depression: a long-term follow-up investigation using 3T-fMRI

Major depression is accompanied by cortical dysfunction including impaired auditory processing of non-speech stimuli. In a previous study, we could show that potent antidepressant treatment with electroconvulsive therapy (ECT) did not lead to full functional normalization of altered fMRI activation patterns in response to sine tones although depressive symptoms improved and remission was achieved in the majority of patients. In a next step, a longitudinal follow-up investigation was conducted looking on neuronal activation over time along with full remission in a subgroup of patients of the previous study in order to address the question whether changes in neuronal activation patterns reflect a more state- or trait-dependent characteristic. Results showed that although clinically remitted, patients still exhibited an increased activity of the secondary auditory cortex and multimodal recruitment of the left cuneus, an area of the visual system. However, activity of recruited secondary visual network had decreased over time. A positive correlation was observed between the number of hospital admissions during the follow-up period and activity of the secondary visual area of the left cuneus at baseline prior to ECT. Thus, although the persistence of differences in activation patterns after sine tone presentation in this follow-up investigation could argue for a potential trait marker of depression characterized by alterations in auditory processing, attenuation of neuronal activation in some areas over time suggests that changes might in part also be state-dependent.

Morphological and functional midbrain phenotypes in Fibroblast Growth Factor 17 mutant mice detected by Mn-enhanced MRI

With increasing efforts to develop and utilize mouse models of a variety of neuro-developmental diseases, there is an urgent need for sensitive neuroimaging methods that enable in vivo analysis of subtle alterations in brain anatomy and function in mice. Previous studies have shown that the brains of Fibroblast Growth Factor 17 null mutants (Fgf17−/−) have anatomical abnormalities in the inferior colliculus (IC)—the auditory midbrain—and minor foliation defects in the cerebellum. In addition, changes in the expression domains of several cortical patterning genes were detected, without overt changes in forebrain morphology. Recently, it has also been reported that Fgf17−/− mutants have abnormal vocalization and social behaviors, phenotypes that could reflect molecular changes in the cortex and/or altered auditory processing / perception in these mice. We used manganese (Mn)-enhanced magnetic resonance imaging (MEMRI) to analyze the anatomical phenotype of Fgf17−/− mutants in more detail than achieved previously, detecting changes in IC, cerebellum, olfactory bulb, hypothalamus and frontal cortex. We also used MEMRI to characterize sound-evoked activity patterns, demonstrating a significant reduction of the active IC volume in Fgf17−/− mice. Furthermore, tone-specific (16- and 40-kHz) activity patterns in the IC of Fgf17−/− mice were observed to be largely overlapping, in contrast to the normal pattern, separated along the dorsal-ventral axis. These results demonstrate that Fgf17 plays important roles in both the anatomical and functional development of the auditory midbrain, and show the utility of MEMRI for in vivo analyses of mutant mice with subtle brain defects.

Altered auditory processing in acutely psychotic never-medicated first-episode patients

Individuals with psychosis fail to differentiate external impulses and suffer from distortions of reality testing. Schizophrenia group illnesses are also associated with deficits in working memory and perception. We examined the manifestations of a very early phase of psychotic illness to automatic auditory deviance detection to clarify the basic mechanisms underlying misinterpretations of perception. Methods: Twenty-five never-medicated patients admitted for hospital evaluation of acute psychosis were studied. Fifty-eight EEG channels were recorded during an auditory oddball paradigm. Event-related potentials (ERPs) time-locked to non-attended deviant auditory stimuli were studied in patients and compared with healthy controls. Auditory processing was examined both at the level of the measured biosignals (standard and deviant responses) and with subtraction waveforms. Topographical differences were characterized using global field power (GFP) and minimum norm estimates. Results: The maximum GFP amplitudes and mean amplitudes of the 58 channels within the time windows corresponding to the previously known ‘N2b’, ‘P3a’ and ‘P3b’ components were clearly reduced in patients when compared to healthy controls. However, the groups did not differ during attention-independent automatic processing corresponding to the ‘N1’ and ‘MMN’ components, or with respect to the peak latencies of the GFP maxima. Conclusions: Impairment of the processing of a deviance in simple auditory input in acutely ill drug-naive first-episode psychotic patients only appears in attention-dependent processing after about 250 ms. The alterations in auditory processing differed between stimulus types, suggesting at least two mechanisms underlying the auditory discrimination impairments in acute psychosis. After 250 ms there was a linear and gradually increasing difference in magnitude between the groups in their responses to deviant stimuli, probably related to arousal. In addition, however, there was a striking difference between the groups in the processing of standard stimuli. The early processing was similar in patients and controls, but the striking difference appeared in later processing. The sensory memory deficits associated with psychosis may be explained by an abnormality in sensory model formation rather than by impaired deviant detection.

Alterations in Auditory Processing of Speech Stimuli During Aging in Healthy Subjects

Studies of auditory processing during aging in man have not provided a consensus on whether aging affects the ability to process speech stimuli. To evaluate the relationship between speech recognition tasks and age, we examined 36 male subjects between the ages of 21 and 83 years, who were screened for the absence of disease, particularly in the cardiovascular and neurologic systems. Measures were obtained on the following tests: pure tone thresholds, speech reception threshold, speech discrimination, low-pass filtered speech, and binaural fusion. A statistically significant correlation was found between pure tone thresholds and age for all frequencies. When the effect of peripheral hearing loss was taken into account, speech measures did not correlate with age, with the exception of low-pass filtered speech in the left ear. Our findings suggest that the aging process in healthy man is not necessarily accompanied by deficits in the processing of speech stimuli beyond those which are due to peripheral hearing loss.