Central Auditory Nervous System Research Articles

Central masking with bilateral cochlear implants

Across bilateral cochlear implants, contralateral threshold shift has been investigated as a function of electrode difference between the masking and probe electrodes. For contralateral electric masking, maximum threshold elevations occurred when the position of the masker and probe electrode was approximately place-matched across ears. The amount of masking diminished with increasing masker-probe electrode separation. Place-dependent masking occurred in both sequentially implanted ears, and was not affected by the masker intensity or the time delay from the masker onset. When compared to previous contralateral masking results in normal hearing, the similarities between place-dependent central masking patterns suggest comparable mechanisms of overlapping excitation in the central auditory nervous system.

Auditory Processing Deficits in Alzheimer’s Disease

The purpose of the current study was to study auditory processing (monaural closure, monaural separation, binaural integration, and binaural separation) skills in subjects withand withoutAlzheimer’s disease. Ten individuals with Alzheimer’s disease and seven individuals without Alzheimer’s disease participated in central auditory processing tasks (degraded speech and dichotic speech). Reduced auditory processing skills were found for the Alzheimer’s group and a pronounced left ear deficit was found for this group (re: control group without Alzheimer’s disease). Results support models that postulate breakdown in information processing mechanisms in the central auditory nervous system in individuals with cognitive decline.

Pathways

Pathways

Auditory Cortical Processing in Noise in Normal-Hearing Young Adults

Objective: The ability to hear in background noise is related to the processing of the incoming acoustic signal in the peripheral auditory system as well as the central auditory nervous system (CANS). Electrophysiological tests have the ability to demonstrate the underlying neural integrity of the CANS, but to date a lack of literature exists demonstrating the effects of background noise on auditory cortical potentials. Therefore, the purpose of this investigation was to systematically investigate the effects of white noise on tone burst-evoked late auditory evoked potentials (N1, P2, and P3) in normal hearing young adults. Study Design: Twenty young-adult normal-hearing individuals served as subjects. A comparison of the late auditory evoked potentials (N1, P2, and P3) was made at multiple signal-to-noise ratios (SNRs) (quiet, + 20, + 10, 0). N1, P2, and P3 were elicited and both amplitude and latency were measured for each of the potentials. A standard oddball paradigm with binaural stimulation was used to evoke the potentials. Repeated Measures Analyses of Variance (ANOVA) were conducted for both the experimental factors of amplitude and latency with within subjects factors of condition (quiet, + 20, + 10, 0). Results: Results indicated no significant differences in N1, P2, or P3 amplitude or latency between the quiet and + 20 SNR condition; however, at poorer SNRs significant N1, P2, and P3 amplitude and/or latency differences were observed. Conclusion: The results indicate a change in higher-order neural function related to the presence of increased noise in the environment.

Structural Abnormalities of the Central Auditory Pathway in Infants with Nonsyndromic Cleft Lip and/or Palate

To investigate possible structural abnormalities of the central auditory pathway in infants with nonsyndromic cleft lip and/or palate (NSCL/P). Twenty-seven Chinese infants with NSCL/P, aged from 6 to 24 months. Morphological magnetic resonance imaging (MRI) measurements of the central auditory nervous system (CANS) in infants with NSCL/P were analyzed and compared with those of age- and sex-matched normal controls. No significant group differences were found in general brain measurements, including volumes of the brain stem and right hemisphere. However, infants with NSCL/P had statistically significantly smaller volumes of the left thalamus and left auditory cortex and notably decreased thickness of the left auditory cortex. Cortical abnormalities were more marked compared with other MRI measurements. Structural CANS abnormalities in infants with NSCL/P may be located mainly in the left cerebral hemisphere. The development and maturation of the auditory cortex in infants with NSCL/P may be abnormal when compared with those of normal children.

Better Together

Better Together

Central auditory nervous system dysfunction in infants with non-syndromic cleft lip and/or palate

Objective Peripheral hearing loss has been commonly reported in children with non-syndromic cleft lip and/or palate (NSCLP) but few studies have provided information about central auditory nervous system (CANS) functioning for this group. The main objective of this study was to explore CANS functioning in infants with NSCLP through analysis of auditory evoked potentials (AEPs). Methods AEPs including auditory brainstem response (ABR), middle latency response (MLR), and mismatch negativity (MMN) recordings were conducted in 34 infants of Chinese ethnicity with NSCLP and an equivalent number of normal controls. Results There was no significant difference in ABR (all measurements, including wave I, III, V latencies, I–V inter-wave latency, and wave V amplitude), or MLR (recordable components, Na, Pa latencies, and Na–Pa amplitude) findings between the two groups. However, infants with NSCLP had a significantly smaller MMN response than their normal controls, using MMN strength as the measurement. Conclusions Significant abnormal auditory evoked potential findings at the cortical level suggest that infants with NSCLP may be at risk of central auditory discrimination dysfunction. Further effort is needed to determine auditory processing abilities in infants with NSCLP.

Top down prefrontal affective modulation of tinnitus with multiple sessions of tDCS of dorsolateral prefrontal cortex

Most forms of tinnitus are attributable to reorganization and hyperactivity in the auditory central nervous system with coactivation of nonauditory brain structures. One such nonauditory brain area is the dorsolateral prefrontal cortex (DLPFC), which is important for the integration of sensory and emotional aspects of tinnitus. Based on extensive evidence that transcranial direct current stimulation can induce significant effects on DLPFC-related cognitive function, we aimed to investigate whether left or right anodal DLFPC tDCS is associated with modulation of tinnitus. We conducted a double-blind, placebo-controlled cross-over study in which 15 subjects with tinnitus were randomly assigned to receive active and sham anodal tDCS over left (n = 8) or right DLPFC (n = 7) for six sessions in a counterbalanced order; the cathode electrode was placed in the contralateral DLPFC. The results demonstrate that both active conditions-irrespective of the anodal position-can decrease tinnitus annoyance but it is not associated with improvements in tinnitus intensity when comparing pre-tDCS versus post-tDCS as well as comparing sham-tDCS versus real tDCS. Also, we show that the anode electrode placed over the left DLPFC modulates depression when comparing pre-tDCS versus post-tDCS as well as comparing sham-tDCS versus real tDCS. In addition, we also show that the anode electrode placed over the right DLPFC modulates anxiety when comparing pre-tDCS versus post-tDCS. This latter effect does not remain when we compare sham-tDCS versus real tDCS. This study further supports the involvement of the prefrontal cortex in the neural network associated with tinnitus, and also provides initial evidence for a potential brain stimulation site for tinnitus treatment in association with other treatments that can reduce tinnitus intensity.

The Utility of Visual Analogs of Central Auditory Tests in the Differential Diagnosis of (Central) Auditory Processing Disorder and Attention Deficit Hyperactivity Disorder

Cacace and McFarland (2005) have suggested that the addition of cross-modal analogs will improve the diagnostic specificity of (C)APD (central auditory processing disorder) by ensuring that deficits observed are due to the auditory nature of the stimulus and not to supra-modal or other confounds. Others (e.g., Musiek et al, 2005) have expressed concern about the use of such analogs in diagnosing (C)APD given the uncertainty as to the degree to which cross-modal measures truly are analogous and emphasize the nonmodularity of the CANs (central auditory nervous system) and its function, which precludes modality specificity of (C)APD. To date, no studies have examined the clinical utility of cross-modal (e.g., visual) analogs of central auditory tests in the differential diagnosis of (C)APD. This study investigated performance of children diagnosed with (C)APD, children diagnosed with ADHD (attention deficit hyperactivity disorder), and typically developing children on three diagnostic tests of central auditory function and their corresponding visual analogs. The study sought to determine whether deficits observed in the (C)APD group were restricted to the auditory modality and the degree to which the addition of visual analogs aids in the ability to differentiate among groups. An experimental repeated measures design was employed. Participants consisted of three groups of right-handed children (normal control, n=10; ADHD, n=10; (C)APD, n=7) with normal and symmetrical hearing sensitivity, normal or corrected-to-normal visual acuity, and no family or personal history of disorders unrelated to their primary diagnosis. Participants in Groups 2 and 3 met current diagnostic criteria for ADHD and (C)APD. Visual analogs of three tests in common clinical use for the diagnosis of (C)APD were used (Dichotic Digits [Musiek, 1983]; Frequency Patterns [Pinheiro and Ptacek, 1971]; and Duration Patterns [Pinheiro and Musiek, 1985]). Participants underwent two 1 hr test sessions separated by at least 1 wk. Order of sessions (auditory, visual) and tests within each session were counterbalanced across participants. ANCOVAs (analyses of covariance) were used to examine effects of group, modality, and laterality (Dichotic/Dichoptic Digits) or response condition (auditory and visual patterning). In addition, planned univariate ANCOVAs were used to examine effects of group on intratest comparison measures (REA, HLD [Humming-Labeling Differential]). Children with both ADHD and (C)APD performed more poorly overall than typically developing children on all tasks, with the (C)APD group exhibiting the poorest performance on the auditory and visual patterns tests but the ADHD and (C)APD group performing similarly on the Dichotic/Dichoptic Digits task. However, each of the auditory and visual intratest comparison measures, when taken individually, was able to distinguish the (C)APD group from both the normal control and ADHD groups, whose performance did not differ from one another. Results underscore the importance of intratest comparison measures in the interpretation of central auditory tests (American Speech-Language-Hearing Association [ASHA], 2005 ; American Academy of Audiology [AAA], 2010). Results also support the "non-modular" view of (C)APD in which cross-modal deficits would be predicted based on shared neuroanatomical substrates. Finally, this study demonstrates that auditory tests alone are sufficient to distinguish (C)APD from supra-modal disorders, with cross-modal analogs adding little if anything to the differential diagnostic process.

Pediatric Speech Perception in Noise

An acceptable acoustical environment is necessary for effective communication and learning. Children who experience abnormally poor speech perception in noise, including those with normal hearing sensitivity, are at risk for speech and language delay, reading disorders, psychosocial problems, and academic failure. The biological bases of speech perception in noise are complex and include processes at cortical as well as sub-cortical levels of the auditory nervous system. In children, the ability to perceive speech in degraded listening conditions improves significantly with age in parallel with developmental changes in the auditory nervous system. Difficulty in listening to speech in noisy surroundings is a common symptom associated with auditory processing disorders (APD). Clinical assessment of speech perception in noise quantifies potential problems that a child might face in daily listening situations. Optimally, pediatric speech in noise tests are designed to meet minimal psychometric criteria. A speech in noise test should be appropriate for the child's age and native language so as to minimize the role of linguistic factors. A diagnosis of APD should not be made based solely on a speech in noise test but, rather, on a battery of tests, each exploring a different suprathreshold auditory process. Speech in noise tests should be used and interpreted with extreme caution when assessing auditory processing in children with co-existing peripheral hearing loss. Children with normal hearing sensitivity, whose performance on tests using competing acoustic signals is below normal, can benefit from specific intervention and the use of signal enhancing devices such as FM systems. Keywords: ABR (auditory brainstem response), APD (auditory processing disorders), CANS (central auditory nervous system), (C)APD [(central) auditory processing disorders], HINT (Hearing In Noise Test), LISN (Listening in Spatialized Noise), MCR (message-to-competition ratio), SNR (signal-to-noise ratio), SRT (speech reception threshold)

Spoken Language Processing Model: Bridging Auditory and Language Processing to Guide Assessment and Intervention

This article outlines the author's conceptualization of the key mechanisms that are engaged in the processing of spoken language, referred to as the spoken language processing model. The act of processing what is heard is very complex and involves the successful intertwining of auditory, cognitive, and language mechanisms. Spoken language processing disorders occur when a breakdown in any of these mechanisms impacts an individual's ability to effectively process and use the information that is heard. The symptoms vary depending on the underlying deficit(s). The primary purpose of this article is to provide the reader with a basic understanding of these mechanisms, and, in turn, enable readers to (a) review the literature concerning processing disorders with discernment and (b) have a foundation for developing a test battery to derive composite profiles of individuals' processing abilities. A review of the literature, overview of the spoken language processing model, and suggested approach to diagnostic assessment are presented. Spoken language processing can break down due to a myriad of underlying causes. Central auditory nervous system deficits can impact not only the initial processing of stimuli but possibly the development of effective language skills. On the other hand, deficits in various cognitive and language mechanisms can similarly impact the auditory processing of speech stimuli. Therefore, it is critical to understand how these mechanisms interact and contribute to the processing of speech stimuli.

Diagnostic Accuracy of Established Central Auditory Processing Test Batteries in Patients with Documented Brain Lesions

The sensitivity, specificity, and efficiency of commonly used behavioral central auditory processing tests and test batteries were determined for 20 individuals with known lesions of the central auditory nervous system (CANS) and related auditory symptoms. Twenty-nine individuals with no known neurological involvement served as the control group. Both groups were administered dichotic digits (DD), competing sentences (CS), frequency patterns (FP), and low-pass filtered speech (FS) tests. Diagnostic indices for individual tests and test batteries comprised of two, three, or four tests were calculated both using a lax criterion in which failure on only one test in a battery led to a positive diagnosis and using a strict criterion in which failure on all tests in the battery was necessary to trigger a positive diagnosis. The test battery providing the best balance between sensitivity and specificity varied as a function of criterion. The two-test DD-FP battery using a strict criterion demonstrated the best balance. Limitations of particular tests, the advantages of larger test batteries to more broadly examine multiple auditory processes, the degree to which the present results can be generalized clinically to populations without known brain lesions, and other clinical considerations are discussed.

Auditory Remediation for Patients With Landau-Kleffner Syndrome

Auditory Remediation for Patients With Landau-Kleffner Syndrome

Sensitivity and specificity of auditory steady-state response testing

INTRODUCTION:The ASSR test is an electrophysiological test that evaluates, among other aspects, neural synchrony, based on the frequency or amplitude modulation of tones.OBJECTIVE:The aim of this study was to determine the sensitivity and specificity of auditory steady‐state response testing in detecting lesions and dysfunctions of the central auditory nervous system. METHODS:Seventy volunteers were divided into three groups: those with normal hearing; those with mesial temporal sclerosis; and those with central auditory processing disorder. All subjects underwent auditory steady‐state response testing of both ears at 500 Hz and 2000 Hz (frequency modulation, 46 Hz). The difference between auditory steady‐state response‐estimated thresholds and behavioral thresholds (audiometric evaluation) was calculated.RESULTS:Estimated thresholds were significantly higher in the mesial temporal sclerosis group than in the normal and central auditory processing disorder groups. In addition, the difference between auditory steady‐state response‐estimated and behavioral thresholds was greatest in the mesial temporal sclerosis group when compared to the normal group than in the central auditory processing disorder group compared to the normal group. DISCUSSION:Research focusing on central auditory nervous system (CANS) lesions has shown that individuals with CANS lesions present a greater difference between ASSR‐estimated thresholds and actual behavioral thresholds; ASSR‐estimated thresholds being significantly worse than behavioral thresholds in subjects with CANS insults. This is most likely because the disorder prevents the transmission of the sound stimulus from being in phase with the received stimulus, resulting in asynchronous transmitter release. Another possible cause of the greater difference between the ASSR‐estimated thresholds and the behavioral thresholds is impaired temporal resolution.CONCLUSIONS:The overall sensitivity of auditory steady‐state response testing was lower than its overall specificity. Although the overall specificity was high, it was lower in the central auditory processing disorder group than in the mesial temporal sclerosis group. Overall sensitivity was also lower in the central auditory processing disorder group than in the mesial temporal sclerosis group.

Efecto de las hormonas sexuales en la audición

Amphibian anurans (frogs and toads) widely use sound communication in social interactions. During breeding season males congregate in pools and ponds, where they emit an acoustic signal, named advertisement call that attracts females and indicates its presence to other males. Previously, it has been established that steroid hormones, along with some neuropeptides, can alter the sensory processing of these signals in the individual recipient, through its effect on nuclei and pathways of the central and peripheral auditory nervous system. One of the ways that hormones may alter the perception and response to acoustic signals of other conspecific males is modulating the intensity threshold of response to these signals. However, this possibility has not been explored in males of any species and there are only scarce data on changes in hearing thresholds of human females during the menstrual cycle, which have not been explained. Given the conserved organization of the nuclei and pathways involved in sound processing and distribution of steroid receptors in the brain of vertebrates, experiments and results obtained in anurans could be the basis for understanding other more complex systems of acoustic communication and social interaction in birds and mammals.

Altered expression of securin (Pttg1) and serpina3n in the auditory system of hearing-impaired Tff3-deficient mice.

Tff3 peptide exerts important functions in cytoprotection and restitution of the gastrointestinal (GI) tract epithelia. Moreover, its presence in the rodent inner ear and involvement in the hearing process was demonstrated recently. However, its role in the auditory system still remains elusive. Our previous results showed a deterioration of hearing with age in Tff3-deficient animals. Present detailed analysis of auditory brain stem response (ABR) measurements and immunohistochemical study of selected functional proteins indicated a normal function and phenotype of the cochlea in Tff3 mutants. However, a microarray-based screening of tissue derived from the auditory central nervous system revealed an alteration of securin (Pttg1) and serpina3n expression between wild-type and Tff3 knock-out animals. This was confirmed by qRT-PCR, immunostaining and western blots. We found highly down-regulated Pttg1 and up-regulated serpina3n expression as a consequence of genetically deleting Tff3 in mice, indicating a potential role of these factors during the development of presbyacusis.

The biological basis of audition.

Audition is one of the fundamental extrasensory percepts in mammals. Two of the primary objectives of audition are to determine where sounds originate from in space and what those sounds are. Neural processing of acoustic signals, which are commonly quite complex under natural conditions, is extensive in the brainstem, midbrain, and thalamus. This processing extracts multiple salient features that are then transmitted to the cerebral cortex. The cerebral cortex is a necessary neural structure for audition, or the perception of acoustic auditory objects and/or events. This entry will review the early processing along the ascending auditory central nervous system from the cochlea to the cerebral cortex. The neural mechanisms of audition will then be explored for spatial and non-spatial perception, drawing largely on examples from non-human primates, but insights gained from other mammalian species will also be covered. How these models relate to current studies in human subjects, using both functional imaging and invasive techniques, will also be explored as well as the types of future studies that will enable us to better understand the neural mechanisms of audition. WIREs Cogni Sci 2011 2 408-418 DOI: 10.1002/wcs.118 For further resources related to this article, please visit the WIREs website.

Audiologic Evaluation of Central Auditory Processing Disorders

Central auditory processing disorder (CAPD) is caused by difficulties in processing auditory information in the central auditory nervous system although the peripheral auditory system is normal. As CAPD can affect listening, understanding, language development and learning, it can be a serious problem for school-aged children. Therefore, a comprehensive assessment and diagnostic procedures are needed for understanding the nature of the presenting difficulties of each individuals suspected of having CAPD. Screening and diagnostic assessments for CAPD were reviewed. Screening tests included a questionnaire, checklists and behavioral tests relating to auditory dysfunctions. Diagnostic assessments included a case history, peripheral assessments, behavioral and electrophysiologic tests. The behavioral CAPD battery could include at least five test areas; temporal processing tests, dichotic tests, monaural low-redundancy tests, binaural interaction tests, and auditory discrimination tests. Although interest in the diagnosis, treatment, and management of CAPD has been growing in various fields, CAPD is not properly identified and treated in Korea due to lack of behavioral testing tools. In order to develop a comprehensive assessment battery for CAPD patients in korea, parameters and age norms of each test should be determined. KEY WORDS：Binaural interaction tests·Central auditory processing disorder·Dichotic tests·Monaural low-redundancy tests·Temporal processing tests.

Manifestações eletrofisiológicas em adultos com HIV/AIDS submetidos e não-submetidos à terapia anti-retroviral

auditory evoked potentials (AEP) assess the neuroelectric activity on the auditory pathway -from the auditory nerve to the cerebral cortex - in response to an acoustic stimulus or event. Studies have demonstrated electrophysiological abnormalities in individuals with HIV/AIDS. to characterize the hearing electrophysiological manifestations in adults with HIV/AIDS by comparing the results obtained in the group exposed to antiretroviral therapy with those obtained in the group not exposed to such treatment. electrophysiological evaluation of hearing (Auditory Brainstem Response - ABR, Auditory Middle Latency Response - AMLR and P300) was conducted in 56 individuals with HIV/AIDS: 24 participants composed group I (not exposed to antiretroviral treatment) and 32 participants composed group II (exposed to treatment). alterations in every AEP were observed in individuals with HIV/ AIDS, especially in the ABR. Indeed, the group exposed to antiretroviral treatment presented more alterations. individuals with HIV/AIDS may present alterations on the central and peripheral auditory nervous system. The group exposed to antiretroviral therapy presents more alterations on the brainstem auditory pathway.

Central Auditory Mechanisms Associated with Cochlear Implantation: An Overview of Selected Studies and Comment

Recently, the evaluation of the role of the central auditory system in the utilization of cochlear implants has received much attention. In order to fully understand the results of cochlear implantation, one must have an understanding of how the brain is influenced by electrical stimulation of the auditory nerve. This review provides an overview of the structure and function of the central auditory nervous system and the changes that occur as a result of cochlear implant use. Evidence of central auditory plasticity is discussed highlighting key imaging and evoked potential studies.