Central Auditory Processing Deficits Research Articles

Asymmetry in Cortical Thickness of the Heschl's Gyrus in Unilateral Ear Canal Atresia.

Unilateral congenital conductive hearing impairment in ear canal atresia leads to atrophy of the gray matter of the contralateral primary auditory cortex or changes in asymmetry pattern if left untreated in childhood. Unilateral ear canal atresia with associated severe conductive hearing loss results in deteriorated sound localization and difficulties in understanding of speech in a noisy environment. Cortical atrophy in the Heschl's gyrus has been reported in acquired sensorineural hearing loss but has not been studied in unilateral conductive hearing loss. We obtained T1w and T2w FLAIR MRI data from 17 subjects with unilateral congenital ear canal atresia and 17 matched controls. Gray matter volume and thickness were measured in the Heschl's gyrus using Freesurfer. In unilateral congenital ear canal atresia, Heschl's gyrus exhibited cortical thickness asymmetry (right thicker than left, corrected p = 0.0012, mean difference 0.25 mm), while controls had symmetric findings. Gray matter volume and total thickness did not differ from controls with normal hearing. We observed cortical thickness asymmetry in congenital unilateral ear canal atresia but no evidence of contralateral cortex atrophy. Further research is needed to understand the implications of this asymmetry on central auditory processing deficits.

19 Auditory and Cognitive Function in Adults Living With and Without HIV

Objective:Hearing consists of peripheral components (outer and middle ear, cochlea) and the central auditory system (cochlear nuclei to the auditory cortex). Speech perception relies on peripheral hearing abilities (i.e., pure-tone thresholds) and central auditory processing (CAP) and cognitive functioning. Specifically, working memory, executive function, attention, and verbal functioning allow for speech understanding. As a result, CAP deficits are also influenced by peripheral hearing sensitivity and cognitive functioning. Assessing CAP deficits can be difficult because of these complex interactions. Prior work has shown persons living with HIV (PWH) are at higher risk for sensorineural hearing loss compared to persons living without HIV (PWOH) after adjusting for age, sex, and noise exposure. Further, HIV is a risk factor for cognitive impairment, one example being Alzheimer's disease (AD) and its precursor, Mild Cognitive Impairment (MCI), with auditory dysfunction occurring in earlier stages of AD. Therefore, the purpose of this study was to evaluate: 1) the peripheral hearing sensitivity and CAP in PWH and PWOH; and 2) the association between cognitive function measures and CAP in PWH and PWOH.Participants and Methods:Participants included 59 PWH (39 men and 20 women, mean age=66.7 years [SD=4.4 years]) and 27 PWOH (13 men and 14 women, mean age=71.9 years [SD=7.1 years]). Participants completed a standard neuropsychological battery assessing the domains of learning, recall, executive function, working memory, verbal fluency, processing speed and motor. Raw scores were transformed to demographically corrected, domain T-scores. Cognitive function was normal for 39 (66.1%) PWH and 16 (59.3%) PWOH while 43 (72.9%) PWH and 17 (63.0%) PWOH were determined to have MCI. Participants with dementia were excluded. Participants also completed a hearing assessment, a portion of which consisted of pure-tone thresholds, peripheral hearing measure, and dichotic digits testing (DDT), a CAP measure. Pure-tone air-conduction thresholds were obtained at octave frequencies from 0.25 through 8 kHz, including 3 and 6 kHz. A pure-tone average (PTA) was calculated from 0.5, 1, 2, and 4 kHz thresholds for each ear. The DDT involves the presentation of numbers from 1 to 10, excluding 7, in which two different digits are presented to one ear while two other digits are simultaneously presented to the opposite ear. The outcome of DDT is percent correct.Results:PWH had slightly lower (i.e., better) mean PTAs in both ears compared to PWOH, but this was not statistically significant. Conversely, PWH had lower percent correct DDT results compared to PWOH, but this difference was also not statistically significant. Participants with impairment in verbal fluency, executive functioning, and working memory had significantly worse DDT results by approximately 10%, but only for right ear data.Conclusions:PWH in our sample had better hearing than PWOH, which can be explained by PWH having a lower mean age. PWH had poorer DDT results, however, indicative of CAP deficits rather than peripheral hearing problems. Poor right ear DDT was associated with impairments specifically in frontal-based cognitive processes with an executive component.

Age-Related Dichotic Listening Skills in Impaired and Non-Impaired Readers: A Comparative Study.

Dichotic listening is the high-level auditory process which enables the perception of different verbal stimuli delivered simultaneously to the right and left ears (binaural integration), as well as the perception of a verbal stimulus presented to one ear while ignoring a different stimulus in the other ear (binaural separation). Deficits in central auditory processing have been reported in children with learning disabilities. The present study aimed to compare dichotic listening performances in right-handed impaired readers (IR) and non-impaired readers (non-IR) according to age. For this, a cross-sectional study was conducted in 120 IR (56 males and 64 females) divided into five age groups and 120 non-IR (63 male and 57 female) matched on chronological age (8 to 9 years; 9 to 10 years; 10 to 12 years; 12 to 18 years; adult). They were tested for binaural integration and binaural separation, allowing for the calculation of dichotic aptitude (DA), ear prevalence (EP), and attentional shift index (ASI). A series of ANOVAs showed an effect of age and of the reading group for all the dichotic-related measures, except for EP. Binaural separation scores were lower in IR who also showed more intrusive responses compared to non-IR. These intrusive responses, which were more frequent on the right ear for IR, decreased with age in both groups. Overall, these results suggest that dichotic listening scores improve with age as the central auditory pathways mature. However, whatever the age, performances are lower in IR than in non-IR. This might be explained by an incomplete maturation of the auditory pathways in IR; an early start for long-term follow-up and auditory training is suggested.

Loss of \u03b24-spectrin impairs Nav channel clustering at the heminode and temporal fidelity of presynaptic spikes in developing auditory brain

Beta-4 (β4)-spectrin, encoded by the gene Sptbn4, is a cytoskeleton protein found at nodes and the axon initial segments (AIS). Sptbn4 mutations are associated with myopathy, neuropathy, and auditory deficits in humans. Related to auditory dysfunction, however, the expression and roles of β4-spectrin at axon segments along the myelinated axon in the developing auditory brain are not well explored. We found during postnatal development, β4-spectrin is critical for voltage-gated sodium channel (Nav) clustering at the heminode along the nerve terminal, but not for the formation of nodal and AIS structures in the auditory brainstem. Presynaptic terminal recordings in Sptbn4geo mice, β4-spectrin null mice, showed an elevated threshold of action potential and increased failures during action potential train at high-frequency. Sptbn4geo mice exhibited a slower central conduction and showed no startle responses, but had normal cochlear function. Taken together, the lack of β4-spectrin impairs Nav clustering at the heminode along the nerve terminal and the temporal fidelity and reliability of presynaptic spikes, leading to central auditory processing deficits during postnatal development.

Deficits in Acoustic Startle Reactivity and Auditory Temporal Processing after Traumatic Brain Injury.

Traumatic brain injury (TBI) exacts significant neurological and financial costs on patients and their families. In adult patients with moderate-to-severe TBI, central auditory impairments have been reported. These auditory impairments may interfere with language receptivity, as observed in children with developmental brain injury. Although rodent models of TBI have been widely used to examine behavioral outcomes, few studies have evaluated how TBI affects higher-order central auditory processing across a range of cue complexities. Here, auditory processing was assessed using a modified acoustic startle paradigm. We used a battery of progressively complex stimuli (single-tone, silent gaps in white noise, and frequency-modulated [FM] sweeps) in adult rats that received unilateral controlled cortical impact injury. TBI subjects showed significant reductions in acoustic startle absolute responses across nearly all stimuli, regardless of cue, duration of stimuli, or cue complexity. Despite this overall reduction of startle magnitudes in injured animals, the detection of single-tone stimuli was comparable between TBI and sham-injured subjects, indicating intact hearing after TBI. TBI subjects showed deficits in rapid gap (5 ms) and FM sweep (175 ms) detection, and, in contrast to shams, they did not improve on detecting silent gaps and FM sweeps across days of testing. Our findings provide evidence for both low-level (brainstem-mediated) and higher-order central auditory processing deficits in a rodent model of TBI, which parallel sensory impairments observed in TBI patients. The present findings support the use of modified pre-pule auditory detection paradigms to investigate clinically relevant processes in TBI.

Central Auditory Processing and the Relationship to Perceived Hearing Difficulty: The Jackson Heart Study.

There are limited population-based studies of central auditory processing (CAP). We aimed to determine the relationship between CAP measures and perceived hearing difficulty (PHD) despite normal pure-tone audiometry in an African-American population. Cross-sectional. Jackson Heart Study (JHS), Jackson, MS. Participants of an African-American cohort (26% men; age 54.2, standard deviations [SD] 9.2) who self-reported hearing difficulty despite normal hearing sensitivity defined as audiometric pure-tone average (PTA-4: average of 500, 1000, 2000, and 4000 Hz) less than or equal to 25 dBHL (n = 911) or across all tested frequencies (PT-AF: 250-8000 Hz) less than or equal to 25 dBHL (n = 516). The Quick Speech-in-Noise (QuickSIN) and Dichotic Digits, Double Pairs (DDT2) tests were used to assess CAP. Logistic regression was used to examine the association between measures of CAP and PHD; adjusted for age, sex, education, and pure tone audiogram. PHD was present in 251 (28%) and 137 (27%) of participants using the PTA-4 and PT-AF models, respectively. Fully adjusted regression models revealed that each one-point increase in QuickSIN increased the odds of reporting PHD by 13.7% (odds ratio [OR] 1.14, p < 0.01, 95% CI: 1.08, 1.19) using the PTA-4 model and 15.0% (OR 1.15, p < 0.01, 95% CI: 1.08, 1.23) using the PT-AF model. For DDT2 testing, each 1% reduction in score, increased the odds of reporting PHD by 7.7% (OR 0.92, p < 0.01, 95% CI: 0.88, 0.97) in a fully adjusted PTA-4 model and 6.6% (OR 0.93, p = 0.04, 95% CI: 0.87, 0.99) in the PT-AF model. CAP deficits were associated with increased odds of PHD in normal hearing participants within the JHS cohort.

Open-Set Phoneme Recognition Performance With Varied Temporal Cues in Younger and Older Cochlear Implant Users.

The goal of this study was to investigate the effect of age on phoneme recognition performance in which the stimuli varied in the amount of temporal information available in the signal. Chronological age is increasingly recognized as a factor that can limit the amount of benefit an individual can receive from a cochlear implant (CI). Central auditory temporal processing deficits in older listeners may contribute to the performance gap between younger and older CI users on recognition of phonemes varying in temporal cues. Phoneme recognition was measured at three stimulation rates (500, 900, and 1800 pulses per second) and two envelope modulation frequencies (50 Hz and unfiltered) in 20 CI participants ranging in age from 27 to 85 years. Speech stimuli were multiple word pairs differing in temporal contrasts and were presented via direct stimulation of the electrode array using an eight-channel continuous interleaved sampling strategy. Phoneme recognition performance was evaluated at each stimulation rate condition using both envelope modulation frequencies. Duration of deafness was the strongest subject-level predictor of phoneme recognition, with participants with longer durations of deafness having poorer performance overall. Chronological age did not predict performance for any stimulus condition. Additionally, duration of deafness interacted with envelope filtering. Participants with shorter durations of deafness were able to take advantage of higher frequency envelope modulations, while participants with longer durations of deafness were not. Age did not significantly predict phoneme recognition performance. In contrast, longer durations of deafness were associated with a reduced ability to utilize available temporal information within the signal to improve phoneme recognition performance.

The Resting State Central Auditory Network: a Potential Marker of HIV-Related Central Nervous System Alterations.

HIV positive (HIV+) individuals with otherwise normal hearing ability show central auditory processing deficits as evidenced by worse performance in speech-in-noise perception compared with HIV negative (HIV-) controls. HIV infection and treatment are also associated with lower neurocognitive screening test scores, suggesting underlying central nervous system damage. To determine how central auditory processing deficits in HIV+ individuals relate to brain alterations in the cortex involved with auditory processing, we compared auditory network (AN) functional connectivity between HIV+ adults with or without speech-in-noise perception difficulties and age-matched HIV- controls using resting-state fMRI. Based on the speech recognition threshold of the hearing-in-noise test, twenty-seven HIV+ individuals were divided into a group with speech-in-noise perception abnormalities (HIV+SPabnl, 38.2 ± 6.8 years; 11 males and 2 females) and one without (HIV+SPnl 34.4 ± 8.8 years; 14 males). An HIV- group with normal speech-in-noise perception (HIV-, 31.3 ± 5.2 years; 9 males and 3 females) was also enrolled. All of these younger and middle-aged adults had normal peripheral hearing determined by audiometry. Participants were studied using resting-state fMRI. Independent component analysis was applied to identify the AN. Group differences in the AN were identified using statistical parametric mapping. Both HIV+ groups had increased functional connectivity (FC) in parts of the AN including the superior temporal gyrus, middle temporal gyrus, supramarginal gyrus, and Rolandic operculum compared to the HIV- group. Compared with the HIV+SPnl group, the HIV+SPabnl group showed greater FC in parts of the AN including the middle frontal and inferior frontal gyri. The classical auditory areas in the temporal lobe are affected by HIV regardless of speech perception ability. Increased temporal FC in HIV+ individuals might reflect functional compensation to achieve normal primary auditory perception. Furthermore, increased frontal FC in the HIV+SPabnl group compared with the HIV+SPnl group suggest that speech-in-noise perception difficulties in HIV-infected adults also affect areas involved in higher-level cognition, providing imaging evidence consistent with the hypothesis that HIV-related neurocognitive deficits can include central auditory processing deficits.

Deficits in central auditory processing among migraine patients

BackgroundMigraine is a neurological disease associated with abnormal excitability in visual, somatosensory, and motor cortex. This study aimed to verify and compare auditory processing performance in migraine patients with and without dizziness and healthy controls.ResultsSixty subjects were divided into 3 groups: control group, twenty normal healthy subjects, and study group I (twenty subjects diagnosed with migraine) and study group II (twenty subjects diagnosed with vestibular migraine). They were evaluated using the Central Auditory Processing Questionnaire for adults, tympanometry, pure tone audiometry, Psychophysical Central Auditory Tests, including Arabic Speech Intelligibility in Noise Test for adults, Arabic Dichotic Digit Test [version II], Gap in Noise Test, Duration Pattern Test, and Arabic Memory Tests. No significant difference was found between the two study groups I and II, but the significant difference was found between the study groups and the control group in all central auditory test results. Statistically significant difference was found between the control group and study groups I and II regarding all memory tests. The highest percentage of abnormality was present in temporal resolution and selective auditory attention in both study groups. There was no significant statistical correlation between the number of attacks/month and central auditory test results. There was no significant statistical correlation between the frequency of attacks in VM patients and central auditory test results.ConclusionsPatients with migraine and vestibular migraine had an inferior performance in all psychophysical central auditory tests when compared with control. Also, there was no significant difference between the 2 study groups regarding central auditory test results which may support that both migraine with and without dizziness have the same pathophysiology.

Central auditory processing deficits in schizophrenia: Effects of auditory-based cognitive training

BackgroundSensory processing abnormalities are common in schizophrenia (SZ) and impact everyday functions, such as speech perception in noisy environments. Auditory-based targeted cognitive training (TCT) is a “bottom up” cognitive remediation intervention designed to enhance the speed and accuracy of low-level auditory information processing. However, the effects of TCT on behavioral measures of central auditory processing (CAP) and the role of CAP function on verbal learning outcomes in SZ are unknown. MethodsSZ (n = 42) and healthy subjects (CTL; n = 18) underwent comprehensive clinical, neurocognitive, and auditory assessments, including tests of hearing sensitivity and speech recognition (Words-in-Noise (WIN), Quick Speech-in-Noise (SIN)). SZ patients were randomized to receive either treatment-as-usual (TAU); or 30-h of TCT + TAU using a stratified, parallel design. SZ patients repeated assessments ~10–12 weeks later. ResultsPatients exhibited deficits in both WIN (p < 0.05, d = 0.50) and SIN (p < 0.01, d = 0.63). A treatment × time interaction on WIN (p < 0.05, d = 0.74), but not SIN discriminability, was seen in the TCT group relative to TAU. Specific enhancements in the 4-dB over background range drove gains in WIN performance. Moreover, SZ patients with greater CAP deficits experienced robust gains in verbal learning after 30-h of TCT relative to SZ patients without CAP impairment (p < 0.01, d = 1.28). ConclusionFindings demonstrate that intensive auditory training enhances the fidelity of auditory processing and perception, such that specific CAP deficits were ‘normalized’ and were predictive of gains in verbal learning after TCT. It is conceivable that patients with deficiencies in CAP measures may benefit most from TCT and other interventions targeting auditory dysfunction in SZ.

Chemogenetic Activation of Cortical Parvalbumin-Positive Interneurons Reverses Noise-Induced Impairments in Gap Detection.

Exposure to loud noises not only leads to trauma and loss of output from the ear but also alters downstream central auditory circuits. A perceptual consequence of noise-induced central auditory disruption is impairment in gap-induced prepulse inhibition, also known as gap detection. Recent studies have implicated cortical parvalbumin (PV)-positive inhibitory interneurons in gap detection and prepulse inhibition. Here, we show that exposure to loud noises specifically reduces the density of cortical PV but not somatostatin (SOM)-positive interneurons in the primary auditory cortex in mice (C57BL/6) of both sexes. Optogenetic activation of PV neurons produced less cortical inhibition in noise-exposed than sham-exposed animals, indicative of reduced PV neuron function. Activation of SOM neurons resulted in similar levels of cortical inhibition in noise- and sham-exposed groups. Furthermore, chemogenetic activation of PV neurons with the hM3-based designer receptor exclusively activated by designer drugs completely reversed the impairments in gap detection for noise-exposed animals. These results support the notions that cortical PV neurons encode gap in sound and that PV neuron dysfunction contributes to noise-induced impairment in gap detection.SIGNIFICANCE STATEMENT Noise-induced hearing loss contributes to a range of central auditory processing deficits (CAPDs). The mechanisms underlying noise-induced CAPDs are still poorly understood. Here we show that exposure to loud noises results in dysfunction of PV-positive but not somatostatin-positive inhibitory interneurons in the primary auditory cortex. In addition, cortical PV inhibitory neurons in noise-exposed animals had reduced expression of glutamic acid decarboxylases and weakened inhibition on cortical activity. Noise exposure resulted in impaired gap detection, indicative of disrupted temporal sound processing and possibly tinnitus. We found that chemogenetic activation of cortical PV inhibitory interneurons alleviated the deficits in gap detection. These results implicate PV neuron dysfunction as a mechanism for noise-induced CAPDs.

Electrophysiological Evidence of Auditory and Cognitive Processing Deficits in Parkinson Disease.

Background Parkinson's disease (PD) patients are at increased risk for central auditory processing (CAP) deficits and cognitive dysfunction. However, behavioral assessments of CAP and cognitive processing used in a previous study by our research team found few significant differences in performance between early-stage PD patients and age-matched control subjects. The objective of this study is to use auditory event-related potentials (AERPs) to compare CAP and cognitive functions in a population of PD patients with a group of age-matched control subjects. Methods AERPs in response to tonal and speech stimuli were recorded from 35 adults who had a medical diagnosis of PD (23 males and 12 females; mean age = 66.9 ± s.d.11.2 years), and 35 age-matched control subjects who did not have PD or any other neurological disorders (31 males and 4 females; mean age = 65.4 ± s.d.12.3 years). Auditory stimuli included pure tones (500 and 1000 Hz) to elicit the P300 response and a dichotic digits paradigm to elicit the N200 processing negativity. Results Compared to control subjects, PD patients exhibited significantly longer latencies of P300 and N200 components and smaller amplitude N200 components. Latency and amplitude of the N200 component were significantly correlated with participants' age. N200 amplitude was correlated with results from the Rey Auditory Verbal Learning Test (RAVLT) of cognitive ability. Latency of the P300 and amplitude of the N200 components were significantly correlated with results from the Spatial Release From Masking (SRM) behavioral CAP assessment. Conclusions AERP assessments used in this study appear to be sensitive indicators of CAP and cognitive deficits exhibited by early-stage PD patients. While few significant differences in performance on behavioral CAP and cognitive tests were previously observed between this population of PD patients and age-matched control subjects, N200 and P300 components recorded in the present study revealed impaired neural processing by the PD group.

Effect of Kv3 channel modulators on auditory temporal resolution in aged Fischer 344 rats

AUT00063 and AUT00202 are novel pharmaceutical modulators of the Kv3 subfamily of voltage-gated K+ channels. Kv3.1 channels, which control fast firing of many central auditory neurons, have been shown to decline with age and this may contribute to age-related deficits in central auditory processing. In the present study, the effects of the two novel compounds that specifically modulate Kv3 channels on auditory temporal processing were examined in aged (19-25-month-old) and young-adult (3-5 month-old) Fischer 344 rats (F344) using a behavioral gap-prepulse inhibition (gap-PPI) paradigm. The acoustic startle response (ASR) and its inhibition induced by a gap in noise were measured before and after drug administration. Hearing thresholds in tested rats were evaluated by the auditory brainstem response (ABR). Aged F344 rats had significantly higher ABR thresholds, lower amplitudes of ASR, and weaker gap-PPI compared with young-adult rats. No influence of AUT00063 and AUT00202 administration was observed on ABR hearing thresholds in rats of both age groups. AUT00063 and AUT00202 had suppressive effect on ASR of F344 rats that was more pronounced with AUT00063. The degree of suppression depended on the dose and age of the rats. Both compounds significantly improved the gap-PPI performance in gap detection tests in aged rats. These results indicate that AUT00063 and AUT00202 may influence intrinsic firing properties of neurons in the central auditory system of aged animals and have the potential to treat aged-related hearing disorders.

Age- and movement-related modulation of cortical oscillations in a mouse model of presbycusis

Brain oscillations are associated with specific cognitive and sensory processes. How age-related hearing loss (presbycusis) alters cortical oscillations is unclear. Altered inhibitory neurotransmission and temporal processing deficits contribute to speech recognition impairments in presbycusis. Specifically, age-related reduction in parvalbumin positive interneurons and perineuronal nets in the auditory cortex predicts a reduction in gamma oscillations that may lead to a decline in temporal precision and attention. To test the hypothesis that resting and evoked gamma oscillations decline with presbycusis, EEGs were recorded from the auditory and frontal cortex of awake, freely moving C57BL/6 J mice at three ages (3, 14 and 24 months). Resting EEG data were analyzed according to movement state (move versus still). Evoked responses were recorded following presentation of noise bursts or amplitude modulated noise with time varying modulation frequencies. We report an age-related decrease in resting gamma power, a decline in gamma-range synchrony to time varying stimuli, and an increase in noise evoked and induced gamma power. A decline in temporal processing is seen in aged mice that exhibit robust auditory-evoked potentials, dissociating hearing loss from temporal processing deficits. We also report an increase in gamma power when mice moved compared to the still state. However, the movement-related modulation of gamma oscillations did not change with age. Together, these data identify a number of novel markers of presbycusis-related changes in auditory and frontal cortex. Because EEGs are commonly recorded in humans, the mouse data may serve as translation relevant preclinical biomarkers to facilitate the development of therapeutics to delay or reverse central auditory processing deficits in presbycusis.

Acquired Central Auditory Processing Disorder in Service Members and Veterans.

Purpose A growing body of evidence suggests that military service members and military veterans are at risk for deficits in central auditory processing. Risk factors include exposure to blast, neurotrauma, hazardous noise, and ototoxicants. We overview these risk factors and comorbidities, address implications for clinical assessment and care of central auditory processing deficits in service members and veterans, and specify knowledge gaps that warrant research. Method We reviewed the literature to identify studies of risk factors, assessment, and care of central auditory processing deficits in service members and veterans. We also assessed the current state of the science for knowledge gaps that warrant additional study. This literature review describes key findings relating to military risk factors and clinical considerations for the assessment and care of those exposed. Conclusions Central auditory processing deficits are associated with exposure to known military risk factors. Research is needed to characterize mechanisms, sources of variance, and differential diagnosis in this population. Existing best practices do not explicitly consider confounds faced by military personnel. Assessment and rehabilitation strategies that account for these challenges are needed. Finally, investment is critical to ensure that Veterans Affairs and Department of Defense clinical staff are informed, trained, and equipped to implement effective patient care.

Main Aspects of Peripheral and Central Hearing System Involvement in Unexplained HIV-Related Hearing Complaints.

Objective: Hearing abnormalities frequently occur in Human Immunodeficiency Virus (HIV) infected individuals. Both conductive and uni- or bilateral sensorineural hearing loss (SNHL) have been described along with other audiological and vestibular symptoms such as tinnitus, vertigo and balance disturbances. While frequent middle ear infections may explain impairment of peripheral hearing abilities, the exact etiology of cochlear, and central auditory processing deficits still remains unclear. Direct effects of HIV, opportunistic infections, ototoxic side effects of antiretroviral therapy (ART), and immunologic responses to the central nervous system involving the auditory pathway have been proposed. We aim to review the audiological profile in HIV infected adults related to the effects of HIV and HAART on the inner ear structures.Methods: We present a review of the literature on cases of HIV related SNHL in adult patients and studies conducted to investigate audiometric changes in such patients. Data on presentation, diagnosis and pathophysiology were reviewed.Results: Sensorineural hearing loss in the higher frequencies is a common form of hearing loss in HIV infected individuals throughout disease progression, along with decreased otoacoustic emission (OAE) responses, increased PTA hearing thresholds and prolonged latencies for auditory brainstem responses (ABR).Conclusion: HIV affects all stages of auditory perception in a way similar to accelerated aging of the auditory system. And we postulate that synaptic loss may be the first step, followed by cochlear damage and central pathology as the virus remains present in all the structures of the auditory pathway causing local inflammation and degeneration. Evaluation of hearing function among all patients diagnosed with HIV infection seems to be an accepted approach; it should include OAE testing, pure tone and speech audiometry, speech-in-noise tests and ABR measurements.

Keys to staying sharp: A randomized clinical trial of piano training among older adults with and without mild cognitive impairment

BackgroundThe prevalence of dementia, the most expensive medical condition (Kirschstein, 2000 and Hurd et al., 2013 [1,2]), and its precursor, mild cognitive impairment (MCI) are increasing [3]. Finding effective intervention strategies to prevent or delay dementia is imperative to public health. Prior research provides compelling evidence that central auditory processing (CAP) deficits are a risk factor for dementia [4–6]. Grounded in the information degradation theory [7, 8], we hypothesize that improving brain function at early perceptual levels (i.e., CAP) may be optimal to attenuate cognitive and functional decline and potentially curb dementia prevalence. Piano training is one avenue to enhance cognition [9–13] by facilitating CAP at initial perceptual stages [14–18]. ObjectivesThe Keys To Staying Sharp study is a two arm, randomized clinical trial examining the efficacy of piano training relative to music listening instruction to improve CAP, cognition, and everyday function among older adults. In addition, the moderating effects of MCI status on piano training efficacy will be examined and potential mediators of intervention effects will be explored. HypothesesWe hypothesize that piano training will improve CAP and cognitive performance, leading to functional improvements. We expect that enhanced CAP will mediate cognitive gains. We further hypothesize that cognitive gains will mediate functional improvements. MethodWe plan to enroll 360 adults aged 60 years and older who will be randomized to piano training or an active control condition of music listening instruction and complete pre- and immediate post- assessments of CAP, cognition, and everyday function.

Central Auditory Processing Deficits in the Elderly

Central Auditory Processing Deficits in the Elderly

Central auditory processing disorders after mild traumatic brain injury

Auditory processing disorders are common following mild traumatic brain injury (mTBI), but the neurocircuitry involved is not well understood. The present study used functional MRI to examine auditory cortex activation patterns during a passive listening task in a normative population and mTBI patients with and without clinical central auditory processing deficits (APD) as defined by the SCAN-3:A clinical battery. Patients with mTBI had overall patterns of lower auditory cortex activation during the listening tasks as compared to normative controls. A significant lateralization pattern (pairwise t-test; p⟨0.05) was observed in normative controls and in those with mTBI and APD during single-side stimulation. Additionally, baseline connectivity between left and right auditory cortices was lower in mTBI patients than in controls (p=0.01) and significantly reduced in the mTBI with APD group (p=0.008). Correlation was also observed between bilateral task-related activation and competing words subscore of the SCAN-3:A. These findings suggest the passive listening task is well suited to probe auditory function in military personnel with an mTBI diagnosis. Further, the study supports the use of multiple approaches for detecting and assessing central auditory deficits to improve monitoring of short- and long-term outcomes.

Auditory Training Reverses Lead (Pb)-Toxicity-Induced Changes in Sound-Azimuth Selectivity of Cortical Neurons.

Lead (Pb) causes significant adverse effects on the developing brain, resulting in cognitive and learning disabilities in children. The process by which lead produces these negative changes is largely unknown. The fact that children with these syndromes also show deficits in central auditory processing, however, indicates a speculative but disturbing relationship between lead-exposure, impaired auditory processing, and behavioral dysfunction. Here we studied in rats the changes in cortical spatial tuning impacted by early lead-exposure and their potential restoration to normal by auditory training. We found animals that were exposed to lead early in life displayed significant behavioral impairments compared with naïve controls while conducting the sound-azimuth discrimination task. Lead-exposure also degraded the sound-azimuth selectivity of neurons in the primary auditory cortex. Subsequent sound-azimuth discrimination training, however, restored to nearly normal the lead-degraded cortical azimuth selectivity. This reversal of cortical spatial fidelity was paralleled by changes in cortical expression of certain excitatory and inhibitory neurotransmitter receptor subunits. These results in a rodent model demonstrate the persisting neurotoxic effects of early lead-exposure on behavioral and cortical neuronal processing of spatial information of sound. They also indicate that attention-demanding auditory training may remediate lead-induced cortical neurological deficits even after these deficits have occurred.