Dichotic listening deficits in amblyaudia are characterized by aberrant neural oscillations in auditory cortex

ObjectiveChildren diagnosed with auditory processing disorder (APD) show deficits in processing complex sounds that are associated with difficulties in higher-order language, learning, cognitive, and communicative functions. Amblyaudia (AMB) is a subcategory of APD characterized by abnormally large ear asymmetries in dichotic listening tasks.MethodsHere, we examined frequency-specific neural oscillations and functional connectivity via high-density electroencephalography (EEG) in children with and without AMB during passive listening of nonspeech stimuli.ResultsTime-frequency maps of these “brain rhythms” revealed stronger phase-locked beta-gamma (~35 Hz) oscillations in AMB participants within bilateral auditory cortex for sounds presented to the right ear, suggesting a hypersynchronization and imbalance of auditory neural activity. Brain-behavior correlations revealed neural asymmetries in cortical responses predicted the larger than normal right-ear advantage seen in participants with AMB. Additionally, we found weaker functional connectivity in the AMB group from right to left auditory cortex, despite their stronger neural responses overall.ConclusionOur results reveal abnormally large auditory sensory encoding and an imbalance in communication between cerebral hemispheres (ipsi- to -contralateral signaling) in AMB.SignificanceThese neurophysiological changes might lead to the functionally poorer behavioral capacity to integrate information between the two ears in children with AMB.     

Artificial Organs 2014: A Year in Review

In this Editor's Review, articles published in 2014 are organized by category and briefly summarized. We aim to provide a brief reflection of the currently available worldwide knowledge that is intended to advance and better human life while providing insight for continued application of technologies and methods of organ Replacement, Recovery, and Regeneration. As the official journal of the International Federation for Artificial Organs, the International Faculty for Artificial Organs, the International Society for Rotary Blood Pumps, the International Society for Pediatric Mechanical Cardiopulmonary Support, and the Vienna International Workshop on Functional Electrical Stimulation, Artificial Organs continues in the original mission of its founders “to foster communications in the field of artificial organs on an international level.” Artificial Organs continues to publish developments and clinical applications of artificial organ technologies in this broad and expanding field of organ Replacement, Recovery, and Regeneration from all over the world. We take this time also to express our gratitude to our authors for offering their work to this journal. We offer our very special thanks to our reviewers who give so generously of time and expertise to review, critique, and especially provide meaningful suggestions to the author's work whether eventually accepted or rejected. Without these excellent and dedicated reviewers, the quality expected from such a journal could not be possible. We also express our special thanks to our Publisher, John Wiley & Sons, for their expert attention and support in the production and marketing of Artificial Organs. We look forward to reporting further advances in the coming years.     

Temporal resolution in individuals with neurological disorders

OBJECTIVE:

Temporal processing refers to the ability of the central auditory nervous system to encode and detect subtle changes in acoustic signals. This study aims to investigate the temporal resolution ability of individuals with mesial temporal sclerosis and to determine the sensitivity and specificity of the gaps-in-noise test in identifying this type of lesion.

METHOD:

This prospective study investigated differences in temporal resolution between 30 individuals with normal hearing and without neurological lesions (G1) and 16 individuals with both normal hearing and mesial temporal sclerosis (G2). Test performances were compared, and the sensitivity and specificity were calculated.

RESULTS:

There was no difference in gap detection thresholds between the two groups, although G1 revealed better average thresholds than G2 did. The sensitivity and specificity of the gaps-in-noise test for neurological lesions were 68% and 98%, respectively.

CONCLUSIONS:

Temporal resolution ability is compromised in individuals with neurological lesions caused by mesial temporal sclerosis. The gaps-in-noise test was shown to be a sensitive and specific measure of central auditory dysfunction in these patients.     

The auditory novelty system: An attempt to integrate human and animal research

In this account, we attempt to integrate two parallel, but thus far, separate lines of research on auditory novelty detection: (1) human studies of EEG recordings of the mismatch negativity (MMN), and (2) animal studies of single‐neuron recordings of stimulus‐specific adaptation (SSA). The studies demonstrating the existence of novelty neurons showing SSA at different levels along the auditory pathway's hierarchy, together with the recent results showing human auditory‐evoked potential correlates of deviance detection at very short latencies, that is, at 20–40 ms from change onset, support the view that novelty detection is a key principle that governs the functional organization of the auditory system. Furthermore, the generation of the MMN recorded from the human scalp seems to involve a cascade of neuronal processing that occurs at different successive levels of the auditory system's hierarchy.     

经听觉统合训练改善听觉传导功能的孤独症谱系障碍患儿核心症状的变化分析

目的探究接受听觉统合训练(auditory integration training,AIT)后听觉传导功能障碍得到缓解的孤独症谱系障碍患儿核心症状的改善情况。方法将存在听觉诱发电位异常的ASD患儿分入AIT组(接受训练后恢复正常的组成试验组)、对照组A组(空白对照组)、对照B组(应用行为分析训练组),分别在各组入组时、入组1个月后、入组3个月后进行波特奇发育检核表、儿童孤独症评定量表(CARS)、孤独症治疗评定量表(ATEC)评估,以各因子分数的变化值评价核心症状改善水平。结果入组时试验组、对照A组及对照B组CARS[分别为(36.31±4.08)分,(36.33±3.76)分,(36.33±5.14)分]及ATEC语言[分别为(19.08±6.43)分,(16.40±6.42)分,(18.48±5.96)分]、社交[分别为(15.63±7.13)分,(16.05±7.57)分,(16.19±7.19)分]、感知[分别为(16.78±5.39)分,(16.92±6.75)分,(17.12±6.73)分]、自理[分别为(15.98±8.71)分、(17.93±8.22)分、(17.26±8.93)]评分均差异无统计学意义(均P>0.05)。入组1月、3月后,重复测量方差分析显示,试验组、对照B组、对照组A组CARS分值[1月:(33.96±3.79)分,(35.09±4.38)分,(34.30±3.98)分;3月:(32.95±3.15)分,(36.86±3.86)分,(33.95±3.90)分]的影响:时间主效应显著(F=22.308,P<0.01),组别主效应不显著(F=2.647,P>0.05),时间与组别存在交互作用(F=8.626,P<0.01);对ATEC语言[1月:(16.18±7.10)分,(18.62±6.63)分,(13.40±5.44)分;3月:(14.13±6.13)分,(18.40±6.35)分,(10.75±5.17)分]、社交[1月:(12.31±6.68)分,(17.76±6.82)分,(15.08±6.75)分;3月:(10.71±5.42)分,(16.31±6.30)分,(12.15±7.30)分]、感知觉[1月:(14.37±5.86)分,(17.43±7.22)分,(18.58±6.92)分;3月:(10.35±5.43)分,(16.44±7.05)分,(16.68±7.37)分]分量表分值的影响,时间主效应显著(F=35.534,40.729,40.401,均P<0.01),组别主效应亦显著(F=7.600,6.193,7.675,均P<0.01),时间与组别存在交互作用(F=7.602,3.355,7.649,均P<0.05),事后多重比较示:试验组与对照B组、对照A组与对照B组在干预后ATEC语言量表分值差异有统计学意义(I1-J1=-1.69,P1<0.05;I2-J2=-4.98,P2<0.01);试验组与对照A组在干预后ATEC社交量表分值差异有统计学意义(I-J=-4.54,P<0.01);试验组与对照A组、试验组与对照B组在干预后ATEC感知觉量表分值差异有统计学意义(I1-J1=-3.16,P1<0.05;I2-J2=-4.89,P2<0.01);对ATEC自理能力分量表分值影响的时间主效应显著(F=22.876,P<0.01),组别主效应亦显著(F=3.427,P<0.05),时间与组别无交互作用(F=1.885,P>0.05),事后多重比较示:试验组与对照A组在干预后ATEC自理能力量表分值差异有统计学意义(I-J=-4.46,P<0.05)。结论AIT训练后听觉传导功能恢复正常的ASD患儿的核心症状也能得到明显改善。     

The Influence of refractoriness upon comprehension of non-verbal auditory stimuli

An investigation of non-verbal auditory comprehension in two patients with global aphasia following stroke is reported. The primary aim of the investigation was to establish whether refractory access disorders can affect non-verbal input modalities. All previous reports of refractoriness, a cognitive syndrome characterized by response inconsistency, sensitivity to temporal factors and insensitivity to item frequency, have involved comprehension tasks which have a verbal component. Two main experiments are described. The first consists of a novel sound-to-picture and sound-to-word matching task in which comprehension of environmental sounds is probed under conditions of semantic relatedness and semantic unrelatedness. In addition to the two stroke patients, the performance of a group of 10 control patients with non-vascular pathology is reported, along with evidence of semantic relatedness effects in sound comprehension. The second experiment examines environmental sound comprehension within a repetitive probing paradigm which affords assessment of the effects of semantic relatedness, response consistency and presentation rate. It is demonstrated that the two stroke patients show a significant increase in error rate across multiple probes of the same set of sound stimuli, indicating the presence of refractoriness within this non-verbal domain. The implications of the results are discussed with reference to our current understanding of the mechanisms of refractoriness.     

Pleasurable emotional response to music: A case of neurodegenerative generalized auditory agnosia

Recent functional neuroimaging studies implicate the network of mesolimbic structures known to be active in reward processing as the neural substrate of pleasure associated with listening to music. Psychoacoustic and lesion studies suggest that there is a widely distributed cortical network involved in processing discreet musical variables. Here we present the case of a young man with auditory agnosia as the consequence of cortical neurodegeneration who continues to experience pleasure when exposed to music. In a series of musical tasks, the subject was unable to accurately identify any of the perceptual components of music beyond simple pitch discrimination, including musical variables known to impact the perception of affect. The subject subsequently misidentified the musical character of personally familiar tunes presented experimentally, but continued to report that the activity of ‘listening’ to specific musical genres was an emotionally rewarding experience. The implications of this case for the evolving understanding of music perception, music misperception, music memory, and music-associated emotion are discussed.     

Oscillatory support for rapid frequency change processing in infants

Rapid auditory processing and auditory change detection abilities are crucial aspects of speech and language development, particularly in the first year of life. Animal models and adult studies suggest that oscillatory synchrony, and in particular low-frequency oscillations play key roles in this process. We hypothesize that infant perception of rapid pitch and timing changes is mediated, at least in part, by oscillatory mechanisms. Using event-related potentials (ERPs), source localization and time-frequency analysis of event-related oscillations (EROs), we examined the neural substrates of rapid auditory processing in 4-month-olds. During a standard oddball paradigm, infants listened to tone pairs with invariant standard (STD, 800–800 Hz) and variant deviant (DEV, 800–1200 Hz) pitch. STD and DEV tone pairs were first presented in a block with a short inter-stimulus interval (ISI) (Rapid Rate: 70 ms ISI), followed by a block of stimuli with a longer ISI (Control Rate: 300 ms ISI). Results showed greater ERP peak amplitude in response to the DEV tone in both conditions and later and larger peaks during Rapid Rate presentation, compared to the Control condition. Sources of neural activity, localized to right and left auditory regions, showed larger and faster activation in the right hemisphere for both rate conditions. Time-frequency analysis of the source activity revealed clusters of theta band enhancement to the DEV tone in right auditory cortex for both conditions. Left auditory activity was enhanced only during Rapid Rate presentation. These data suggest that local low-frequency oscillatory synchrony underlies rapid processing and can robustly index auditory perception in young infants. Furthermore, left hemisphere recruitment during rapid frequency change discrimination suggests a difference in the spectral and temporal resolution of right and left hemispheres at a very young age.     

Longitudinal study of single‐word comprehension in semantic dementia: A comparison with primary progressive aphasia and Alzheimer's disease

Background: Although semantic dementia (SD) is characterised by a multimodal loss of semantic knowledge, it has been demonstrated that lexical‐semantic representations are not equally disrupted in SD and that some categories may be recognised better than others. Little is known, however, about the pattern of the category‐specific comprehension deficits in SD and whether it differs from that of other forms of progressive aphasias.

Aims: This exploratory study aimed to investigate the evolution of category‐specific deficits of single‐word comprehension in progressive aphasias.

Methods & Procedures: A total of 19 patients with a clinical diagnosis of SD, 25 patients with primary progressive aphasia with agrammatic and relatively nonfluent speech (PPA), and 25 patients with Alzheimer's disease (AD) with aphasia were studied longitudinally with the Western Aphasia Battery (WAB). The Auditory Word Recognition subtest of the WAB was utilised to assess comprehension of words derived from different semantic categories.

Outcomes & Results: The analysis revealed that, over time, category‐specific deficits of single‐word comprehension were seen in all three groups of patients. Participants with SD as well as those with PPA and AD were impaired on both pointing to fingers and the right–left orientation task. However, patients with SD were the only group that showed defective recognition of their own body parts. Interestingly, individuals with SD had no difficulties identifying colours, letters, and numbers, even during the follow‐up testing. In addition, in all three groups the extent of category‐specific deficits was associated with the severity of aphasia.

Conclusions: These results indicate that category‐specific deficits of single‐word comprehension are frequently seen not only in patients with SD but also in individuals with PPA or AD, and that the extent of these deficits is associated with the severity of aphasia. However, the pattern of these deficits is often different in these three forms of neurodegenerative conditions and more dissociations between semantic categories are observed as each of these diseases progresses.