Frontiers in neuroscience
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Frontiers in neuroscience · Jan 2017
Outer Hair Cell and Auditory Nerve Function in Speech Recognition in Quiet and in Background Noise.
The goal of this study was to describe the contribution of outer hair cells (OHCs) and the auditory nerve (AN) to speech understanding in quiet and in the presence of background noise. Fifty-three human subjects with hearing ranging from normal to moderate sensorineural hearing loss were assayed for both speech in quiet (Word Recognition) and speech in noise (QuickSIN test) performance. ⋯ The results indicated that (1) OHC dysfunction was evident in the lower range of normal audiometric thresholds, which demonstrates that OHC damage can produce "Hidden Hearing Loss," (2) AN dysfunction was evident beginning at mild levels of hearing loss, (3) when controlled for normal OHC function, persons exhibiting either high or low ECochG amplitudes exhibited no statistically significant differences in neither speech in quiet nor speech in noise performance, (4) speech in noise performance was correlated with OHC function, (5) hearing impaired subjects with OHC dysfunction exhibited better speech in quiet performance at or near threshold when stimuli were presented at equivalent sensation levels. These results show that OHC dysfunction contributes to hidden hearing loss, OHC function is required for optimum speech in noise performance, and those persons with sensorineural hearing loss exhibit better word discrimination in quiet at or near their audiometric thresholds than normal listeners.
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Frontiers in neuroscience · Jan 2017
Modulation of Illusory Auditory Perception by Transcranial Electrical Stimulation.
The aim of the present study was to test whether transcranial electrical stimulation can modulate illusory perception in the auditory domain. In two separate experiments we applied transcranial Direct Current Stimulation (anodal/cathodal tDCS, 2 mA; N = 60) and high-frequency transcranial Random Noise Stimulation (hf-tRNS, 1.5 mA, offset 0; N = 45) on the temporal cortex during the presentation of the stimuli eliciting the Deutsch's illusion. The illusion arises when two sine tones spaced one octave apart (400 and 800 Hz) are presented dichotically in alternation, one in the left and the other in the right ear, so that when the right ear receives the high tone, the left ear receives the low tone, and vice versa. ⋯ The results revealed that neither anodal nor cathodal tDCS applied over the left/right temporal cortex modulated the perception of the illusion, whereas hf-tRNS applied bilaterally on the temporal cortex reduced the number of times the sequence of sounds is perceived as the Deutsch's illusion with respect to the sham control condition. The stimulation time before the beginning of the task (5 or 15 min) did not influence the perceptual outcome. In accordance with previous findings, we conclude that hf-tRNS can modulate auditory perception more efficiently than tDCS.
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Frontiers in neuroscience · Jan 2017
ReviewNeural Interfaces for Intracortical Recording: Requirements, Fabrication Methods, and Characteristics.
Implantable neural interfaces for central nervous system research have been designed with wire, polymer, or micromachining technologies over the past 70 years. Research on biocompatible materials, ideal probe shapes, and insertion methods has resulted in building more and more capable neural interfaces. ⋯ The performance of neural interfaces in chronic settings often degrades due to foreign body response to the implant that is initiated by the surgical procedure, and related to the probe structure, and material properties used in fabricating the neural interface. In this review, we identify the key requirements for neural interfaces for intracortical recording, describe the three different types of probes-microwire, micromachined, and polymer-based probes; their materials, fabrication methods, and discuss their characteristics and related challenges.
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Frontiers in neuroscience · Jan 2017
Activation and Functional Connectivity of the Left Inferior Temporal Gyrus during Visual Speech Priming in Healthy Listeners and Listeners with Schizophrenia.
Under a "cocktail-party" listening condition with multiple-people talking, compared to healthy people, people with schizophrenia benefit less from the use of visual-speech (lipreading) priming (VSP) cues to improve speech recognition. The neural mechanisms underlying the unmasking effect of VSP remain unknown. This study investigated the brain substrates underlying the unmasking effect of VSP in healthy listeners and the schizophrenia-induced changes in the brain substrates. ⋯ Compared to healthy listeners, listeners with schizophrenia showed significantly lower VSP-induced activation of the left pITG and reduced functional connectivity of the left pITG with the bilateral Rolandic operculum, bilateral STG, and left insular. Thus, the left pITG and its functional connectivity may be the brain substrates related to the unmasking effect of VSP, assumedly through enhancing both the processing of target visual-speech signals and the inhibition of masking-speech signals. In people with schizophrenia, the reduced unmasking effect of VSP on speech recognition may be associated with a schizophrenia-related reduction of VSP-induced activation and functional connectivity of the left pITG.
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Frontiers in neuroscience · Jan 2017
Serum Oxytocin Levels and an Oxytocin Receptor Gene Polymorphism (rs2254298) Indicate Social Deficits in Children and Adolescents with Autism Spectrum Disorders.
The neuropeptide oxytocin (OT) and its receptor (OXTR) have been predicted to be involved in the regulation of social functioning in autism spectrum disorders (ASD). Objective of the study was to investigate serum OT levels and the OXTR rs2254298 polymorphism in Chinese Han children and adolescents with ASD as well as to identify their social deficits relevant to the oxytocinergic system. We tested serum OT levels using ELISA in 55 ASD subjects and 110 typically developing (TD) controls as well as genotyped the OXTR rs2254298 polymorphism using PCR-RFLP in 100 ASD subjects and 232 TD controls. ⋯ However, ASD subjects exhibited elevated serum OT levels compared to TD controls and positive correlations between serum OT levels and "adaptation to change score" in the CARS and CARS total scores. Moreover, in the ASD group, significant relationships were revealed between the single-nucleotide polymorphism (SNP) rs2254298 and serum OT levels, the category "stereotypes and object use" in the ABC and the category "adaptation to change" in the CARS. These findings indicated that individuals with ASD may exhibit a dysregulation in OT on the basis of changes in OXTR gene expression as well as environmentally induced alterations of the oxytocinergic system to determine their social deficits.