Human frequency following responses to iterated rippled noise with positive and negative gain: Differential sensitivity to waveform envelope and temporal fine-structure

Publication date: September 2018

Source: Hearing Research, Volume 367

Author(s): Saradha Ananthakrishnan, Ananthanarayan Krishnan

Abstract

The perceived pitch of iterated rippled noise (IRN) with negative gain (IRNn) is an octave lower than that of IRN with positive gain (IRNp). IRNp and IRNn have identical waveform envelopes (ENV), but differing stimulus waveform fine structure (TFS), which likely accounts for this perceived pitch difference. Here, we examine whether differences in the temporal pattern of phase-locked activity reflected in the human brainstem Frequency Following Response (FFR) elicited by IRNp and IRNn can account for the differences in perceived pitch for the two stimuli. FFRs using a single onset polarity were measured in 13 normal-hearing, adult listeners in response to IRNp and IRNn stimuli with 2 ms, and 4 ms delay. Autocorrelation functions (ACFs) and Fast Fourier Transforms (FFTs) were used to evaluate the dominant periodicity and spectral pattern (harmonic spacing) in the phase-locked FFR neural activity. For both delays, the harmonic spacing in the spectra corresponded more strongly with the perceived lowering of pitch from IRNp to IRNn, compared to the ACFs. These results suggest that the FFR elicited by a single polarity stimulus reflects phase-locking to both stimulus ENV and TFS. A post-hoc experiment evaluating the FFR phase-locked activity to ENV (FFR_ENV), and TFS (FFR_TFS) elicited by IRNp and IRNn confirmed that only the phase-locked activity to the TFS, reflected in FFR_TFS, showed differences in both spectra and ACF that closely matched the pitch difference between the two stimuli. The results of the post-hoc experiment suggests that pitch-relevant information is preserved in the temporal pattern of phase-locked activity and suggests that the differences in stimulus ENV and TFS driving the pitch percept of IRNp and IRNn are preserved in the brainstem neural response. The scalp recorded FFR may provide for a noninvasive analytic tool to evaluate the relative contributions of envelope and temporal fine-structure in the neural representation of complex sounds in humans.

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Detection of single mRNAs in individual cells of the auditory system

Publication date: September 2018

Source: Hearing Research, Volume 367

Author(s): Pezhman Salehi, Charlie N. Nelson, Yingying Chen, Debin Lei, Samuel D. Crish, Jovitha Nelson, Hongyan Zuo, Jianxin Bao

Abstract

Gene expression analysis is essential for understanding the rich repertoire of cellular functions. With the development of sensitive molecular tools such as single-cell RNA sequencing, extensive gene expression data can be obtained and analyzed from various tissues. Single-molecule fluorescence in situ hybridization (smFISH) has emerged as a powerful complementary tool for single-cell genomics studies because of its ability to map and quantify the spatial distributions of single mRNAs at the subcellular level in their native tissue. Here, we present a detailed method to study the copy numbers and spatial localizations of single mRNAs in the cochlea and inferior colliculus. First, we demonstrate that smFISH can be performed successfully in adult cochlear tissue after decalcification. Second, we show that the smFISH signals can be detected with high specificity. Third, we adapt an automated transcript analysis pipeline to quantify and identify single mRNAs in a cell-specific manner. Lastly, we show that our method can be used to study possible correlations between transcriptional and translational activities of single genes. Thus, we have developed a detailed smFISH protocol that can be used to study the expression of single mRNAs in specific cell types of the peripheral and central auditory systems.

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Editorial Board

Publication date: September 2018

Source: Hearing Research, Volume 367

Author(s):

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Editorial introduction: The 6th International Conference on Auditory Cortex

Publication date: September 2018

Source: Hearing Research, Volume 366

Author(s): Blake E. Butler, Yale E. Cohen, Stephen G. Lomber

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Editorial Board

Publication date: September 2018

Source: Hearing Research, Volume 366

Author(s):

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Stimulus-specific adaptation in the anesthetized mouse revealed by brainstem auditory evoked potentials

Publication date: Available online 31 August 2018

Source: Hearing Research

Author(s): Daniel Duque, Rui Pais, Manuel S. Malmierca

Abstract

Neural responses to sensory inputs in a complex and natural environment must be weighted according to their relevance. To do so, the brain needs to be able to deal with sudden stimulus fluctuations in an ever-changing acoustic environment. Stimulus-specific adaptation (SSA) is a phenomenon of some neurons along the auditory pathway that show a reduced response to repetitive sounds while responsive to those that occur rarely. SSA has been shown from the inferior colliculus to auditory cortex, but has not been detected in the cochlear nucleus. To discover where SSA is first generated along the auditory pathway, auditory brainstem responses (ABRs) to pure tones were evaluated in anesthetized mice using an oddball paradigm. Using a typical narrow band-pass filter, changes in the ABRs suggest unspecific short-term adaptation may occur as early as the auditory nerve fibers. Furthermore, after applying a wide band-pass filter –allowing the visualization of a late slow wave in the ABR– we found a reduction of the amplitude of the response to repetitive sounds, compared to rare ones, in the slow wave component P₀ that follow the fast wave V. Previous studies have shown the P₀ shows temporal correlation with the sustained responses of inferior colliculus, thus we suggest that this nucleus is the first to show stimulus specific adaptation in the auditory pathway.

Graphical abstract

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Brain-like Emergent Auditory Learning: A Developmental Method

Publication date: Available online 31 August 2018

Source: Hearing Research

Author(s): Dongshu Wang, Hui Shan, Jianbin Xin

Abstract

Compared with machine audition, the human auditory system can recognize speech accurately and quickly. This paper proposes a new developmental network (DN) that simulates the human auditory system and constructs an artificial auditory model for speech recognition. The new model simulates each key element of the human auditory pathway as a deep network; in particular, an additional layer in the network is considered to simulate the function of the superior colliculus in the thalamus for speech context integration. The mel-frequency cepstral coefficient (MFCC) is used to extract the features of the speech signal as the sensory input of the DN. The emergent feature of DN model provides an explanation of how such internal neurons represent the short speech context when they are not supervised by the external world. The experimental results show that the recognition rates of English words and phrases can be improved significantly compared to those reported in the existing literature. The proposed DN model provides a new method to solve difficult problems, such as universal speech recognition, in traditional machine audition systems. Meanwhile, the same learning principle can potentially be used in or adapted to other computational contexts and applications.

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