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Publications using the RP2.1

292 published studies used the RP2.1.

bioRxiv · Dec 2021

The what and where of synchronous sound perception (opens in a new tab)

Guus C. Van Bentum, A. John Van Opstal, Marc M. Van Wanrooij

RP2.1System 3Psychoacoustics
Abstract

A bstract Sound localization and identification are challenging in acoustically rich environments. The relation between these two processes is still poorly understood. As natural sound-sources rarely occur exactly simultaneously, we wondered whether the auditory system could identify (“what”) and localize (“where”) two spatially separated sounds with synchronous onsets. While listeners typically report hearing a single source at an average location, one study found that both sounds may be accurately localized if listeners are explicitly being told two sources exist. We here tested whether simultaneous source identification (one vs. two) and localization is possible, by letting listeners choose to make either one or two head-orienting saccades to the perceived location(s). Results show that listeners could identify two sounds only when presented on different sides of the head, and that identification accuracy increased with their spatial separation. Notably, listeners were unable to accurately localize either sound, irrespective of whether one or two sounds were identified. Instead, the first (or only) response always landed near the average location, while second responses were unrelated to the targets. We conclude that localization of synchronous sounds in the absence of prior information is impossible. We discuss that the putative cortical ‘what’ pathway may not transmit relevant information to the ‘where’ pathway. We examine how a broadband interaural correlation cue could help to correctly identify the presence of two sounds without being able to localize them. We propose that the persistent averaging behavior reveals that the ‘where’ system intrinsically assumes that synchronous sounds originate from a single source. S ignificance S tatement It is poorly understood whether identification (‘what’) of sounds and their localization (‘where’) are inter-related, or independent neural processes. We measured sound-localization responses towards synchronous sounds to examine potential coupling of these processes. We varied the spatial configurations of two sounds and found that although identification improved considerably with larger spatial separation, their localization was unaffected: responses were always directed towards the average location. This shows absence of mutual coupling of information between the ‘what’ and ‘where’ streams in the auditory system. We also show how broadband interaural correlation could explain the improved identification results, without affecting localization performance, and explain how the persistent spatial averaging could be understood from strong internal priors regarding sound synchronicity.

Neurophotonics · Dec 2021

Comparison of functional activation responses from the auditory cortex derived using multi-distance frequency domain and continuous wave near-infrared spectroscopy (opens in a new tab)

Penaz Parveen Sultana Mohammad, Sittiprapa Isarangura, Ann Eddins, Ashwin B. Parthasarathy

PA5RP2.1BioSigHB6SigGenABR/DPOAE
Abstract

Significance: Quantitative measurements of cerebral hemodynamic changes due to functional activation are widely accomplished with commercial continuous wave (CW-NIRS) instruments despite the availability of the more rigorous multi-distance frequency domain (FD-NIRS) approach. A direct comparison of the two approaches to functional near-infrared spectroscopy can help in the interpretation of optical data and guide implementations of diffuse optical instruments for measuring functional activation. Aim: We explore the differences between CW-NIRS and multi-distance FD-NIRS by comparing measurements of functional activation in the human auditory cortex. Approach: Functional activation of the human auditory cortex was measured using a commercial frequency domain near-infrared spectroscopy instrument for 70 dB sound pressure level broadband noise and pure tone (1000 Hz) stimuli. Changes in tissue oxygenation were calculated using the modified Beer–Lambert law (CW-NIRS approach) and the photon diffusion equation (FD-NIRS approach). Results: Changes in oxygenated hemoglobin measured with the multi-distance FD-NIRS approach were about twice as large as those measured with the CW-NIRS approach. A finite-element simulation of the functional activation problem was performed to demonstrate that tissue oxygenation changes measured with the CW-NIRS approach is more accurate than that with multi-distance FD-NIRS. Conclusions: Multi-distance FD-NIRS approaches tend to overestimate functional activation effects, in part due to partial volume effects.

Audiology Research · Dec 2021

Verification of a Mobile Psychoacoustic Test System (opens in a new tab)

Jordana C. Soares, Sangamanatha A. Veeranna, Vijay Parsa, … Prudence Allen

Abstract

Many hearing difficulties can be explained as a loss of audibility, a problem easily detected and treated using standard audiological procedures. Yet, hearing can be much poorer (or more impaired) than audibility predicts because of deficits in the suprathreshold mechanisms that encode the rapidly changing, spectral, temporal, and binaural aspects of the sound. The ability to evaluate these mechanisms requires well-defined stimuli and strict adherence to rigorous psychometric principles. This project reports on the comparison between a laboratory-based and a mobile system’s results for psychoacoustic assessment in adult listeners with normal hearing. A description of both systems employed is provided. Psychoacoustic tests include frequency discrimination, amplitude modulation detection, binaural encoding, and temporal gap detection. Results reported by the mobile system were not significantly different from those collected with the laboratory-based system for most of the tests and were consistent with those reported in the literature. The mobile system has the potential to be a feasible option for the assessment of suprathreshold auditory encoding abilities.

bioRxiv · Dec 2021

Speech Sound Discrimination by Mongolian Gerbils (opens in a new tab)

Carolin Jüchter, Rainer Beutelmann, Georg Martin Klump

Abstract

The present study establishes the Mongolian gerbil ( Meriones unguiculatus ) as a model for investigating the perception of human speech sounds. We report data on the discrimination of logatomes (CVCs 1 - consonant-vowel-consonant combinations with outer consonants /b/, /d/, /s/ and /t/ and central vowels /a/, /a:/, /ε/, /e:/, /I/, /i:/, /ɔ/, /o:/, /℧/ and /u:/, VCVs 2 - vowel-consonant-vowel combinations with outer vowels /a/, /I/ and /℧/ and central consonants /b/, /d/, /f/, /g/, /k/, /l/, /m/, /n/, /p/, /s/, /t/ and /v/) by young gerbils. Four young gerbils were trained to perform an oddball target detection paradigm in which they were required to discriminate a deviant CVC or VCV in a sequence of CVC or VCV standards, respectively. The experiments were performed with an ICRA-1 noise masker with speech-like spectral properties, and logatomes of multiple speakers were presented at various signal-to-noise ratios. Response latencies were measured to generate perceptual maps employing multidimensional scaling, which visualize the gerbils’ internal representations of the sounds. The dimensions of the perceptual maps were correlated to multiple phonetic features of the speech sounds for evaluating which features of vowels and consonants are most important for the discrimination. The perceptual representation of vowels and consonants in gerbils was similar to that of humans, although gerbils needed higher signal-to-noise ratios for the discrimination of speech sounds than humans. The gerbils’ discrimination of vowels depended on differences in the frequencies of the first and second formant determined by tongue height and position. Consonants were discriminated based on differences in combinations of their articulatory features. The similarities in the perception of logatomes by gerbils and humans renders the gerbil a suitable model for human speech sound discrimination. Highlights Perceptual maps of vowels and consonants in Mongolian gerbils are derived Gerbils perceive vowels and consonants in the same way as humans Gerbils discriminate vowels based on frequency differences of the formants Gerbils discriminate consonants based on differences in articulatory features

JASA Express Letters · Dec 2021

Interaural-time-difference thresholds for broad band-limited pulses are affected by relative bandwidth not temporal envelope sharpness (opens in a new tab)

Paul G. Mayo, Philip C. Saunders, Matthew J. Goupell

Abstract

Humans are sensitive to interaural time differences (ITDs) conveyed by slow modulations on high-frequency carrier signals. Sensitivity appears to be affected by temporal envelope sharpness, but it is unclear if there is a limit to which sharpness affects sensitivity. Pulse trains were varied in relative bandwidth (re: critical bandwidths) and center frequency. ITD sensitivity increased with increasing bandwidth. There was no effect of center frequency when relative bandwidths were analyzed, suggesting that the temporal envelope sharpness (concomitantly absolute bandwidth in Hz) did not affect performance. Rather, sensitivity was most easily explained by recruitment of additional auditory channels.

Frontiers in Cell and Developmental Biology · Oct 2021

Generation of a Spiral Ganglion Neuron Degeneration Mouse Model (opens in a new tab)

Zhengqing Hu, Fnu Komal, Aditi Singh, Meng Deng

Abstract

Spiral ganglion neurons (SGNs) can be injured by a wide variety of insults. However, there still is a lack of degeneration models to specifically damage the SGNs without disturbing other types of cells in the inner ear. This study aims to generate an SGN-specific damage model using the Cre-LoxP transgenic mouse strains. The Cre-inducible diphtheria toxin receptor ( iDTR +/+ ) knock-in mouse strain was crossed with a mouse strain with Cre activity specific to neurons ( Nefl CreER/CreER ). Expression of the Cre-recombinase activity was evaluated using the reporter mouse strain Ai9 at pre-hearing, hearing onset, and post-hearing stages. Accordingly, heterozygous Nefl CreER/ + ;iDTR +/– mice were treated with tamoxifen on postnatal days 1–5 (P1–5), followed by diphtheria toxin (DT) or vehicle injection on P7, P14, and P21 to evaluate the SGN loss. Robust tamoxifen-induced Cre-mediated Ai9 tdTomato fluorescence was observed in the SGN area of heterozygous Nefl CreER/ + ;Ai9 +/– mice treated with tamoxifen, whereas vehicle-treated heterozygote mice did not show tdTomato fluorescence. Compared to vehicle-treated Nefl CreER/ + ;iDTR +/– mice, DT-treated Nefl CreER/ + ;iDTR +/– mice showed significant auditory brainstem response (ABR) threshold shifts and SGN cell loss. Hair cell count and functional study did not show significant changes. These results demonstrate that the Nefl CreER/CreER mouse strain exhibits inducible SGN-specific Cre activity in the inner ear, which may serve as a valuable SGN damage model for regeneration research of the inner ear.

Frontiers in Psychology · Oct 2021

Sound Localization in Single-Sided Deaf Participants Provided With a Cochlear Implant (opens in a new tab)

Alexandra Annemarie Ludwig, Sylvia Meuret, Rolf-Dieter Battmer, … Arne Ernst

Abstract

Spatial hearing is crucial in real life but deteriorates in participants with severe sensorineural hearing loss or single-sided deafness. This ability can potentially be improved with a unilateral cochlear implant (CI). The present study investigated measures of sound localization in participants with single-sided deafness provided with a CI. Sound localization was measured separately at eight loudspeaker positions (4°, 30°, 60°, and 90°) on the CI side and on the normal-hearing side. Low- and high-frequency noise bursts were used in the tests to investigate possible differences in the processing of interaural time and level differences. Data were compared to normal-hearing adults aged between 20 and 83. In addition, the benefit of the CI in speech understanding in noise was compared to the localization ability. Fifteen out of 18 participants were able to localize signals on the CI side and on the normal-hearing side, although performance was highly variable across participants. Three participants always pointed to the normal-hearing side, irrespective of the location of the signal. The comparison with control data showed that participants had particular difficulties localizing sounds at frontal locations and on the CI side. In contrast to most previous results, participants were able to localize low-frequency signals, although they localized high-frequency signals more accurately. Speech understanding in noise was better with the CI compared to testing without CI, but only at a position where the CI also improved sound localization. Our data suggest that a CI can, to a large extent, restore localization in participants with single-sided deafness. Difficulties may remain at frontal locations and on the CI side. However, speech understanding in noise improves when wearing the CI. The treatment with a CI in these participants might provide real-world benefits, such as improved orientation in traffic and speech understanding in difficult listening situations.

Frontiers in Neuroscience · Oct 2021

Serotonin Transporter Defect Disturbs Structure and Function of the Auditory Cortex in Mice (opens in a new tab)

Wenlu Pan, Jing Pan, Yan Zhao, … Jie Tang

Abstract

Serotonin transporter (SERT) modulates the level of 5-HT and significantly affects the activity of serotonergic neurons in the central nervous system. The manipulation of SERT has lasting neurobiological and behavioral consequences, including developmental dysfunction, depression, and anxiety. Auditory disorders have been widely reported as the adverse events of these mental diseases. It is unclear how SERT impacts neuronal connections/interactions and what mechanism(s) may elicit the disruption of normal neural network functions in auditory cortex. In the present study, we report on the neuronal morphology and function of auditory cortex in SERT knockout (KO) mice. We show that the dendritic length of the fourth layer (L-IV) pyramidal neurons and the second-to-third layer (L-II/III) interneurons were reduced in the auditory cortex of the SERT KO mice. The number and density of dendritic spines of these neurons were significantly less than those of wild-type neurons. Also, the frequency-tonotopic organization of primary auditory cortex was disrupted in SERT KO mice. The auditory neurons of SERT KO mice exhibited border frequency tuning with high-intensity thresholds. These findings indicate that SERT plays a key role in development and functional maintenance of auditory cortical neurons. Auditory function should be examined when SERT is selected as a target in the treatment for psychiatric disorders.

JASA Express Letters · Oct 2021

Intracranial lateralization bias observed in the presence of symmetrical hearing thresholds (opens in a new tab)

Matthew J. Goupell, Virginia Best, H. Steven Colburn

Abstract

It is generally assumed that listeners with normal audiograms have relatively symmetric hearing, and more specifically that diotic stimuli (having zero interaural differences) are heard as centered in the head. While measuring intracranial lateralization with a visual pointing task for tones and 50-Hz-wide narrowband noises from 300 to 700 Hz, examples of systematic and large (>50% from midline to the ear) lateralization biases were found. In a group of ten listeners, five showed consistent lateralization bias to the right or left side at all or a subset of frequencies. Asymmetries in hearing, not apparent in audiometric thresholds, may explain these lateralization biases.

JCI Insight · Aug 2021

Scn2a severe hypomorphic mutation decreases excitatory synaptic input and causes autism-associated behaviors (opens in a new tab)

Hong-Gang Wang, Charlotte C. Bavley, Anfei Li, … Geoffrey S. Pitt

Abstract

SCN2A , encoding the neuronal voltage-gated Na + channel Na V 1.2, is one of the most commonly affected loci linked to autism spectrum disorders (ASDs). Most ASD-associated mutations in SCN2A are loss-of-function mutations, but studies examining how such mutations affect neuronal function and whether Scn2a mutant mice display ASD endophenotypes have been inconsistent. We generated a protein truncation variant Scn2a mouse model ( Scn2a Δ1898/+ ) by CRISPR that eliminates the Na V 1.2 channel’s distal intracellular C-terminal domain, and we analyzed the molecular and cellular consequences of this variant in a heterologous expression system, in neuronal culture, in brain slices, and in vivo. We also analyzed multiple behaviors in WT and Scn2a Δ1898/+ mice and correlated behaviors with clinical data obtained in human subjects with SCN2A variants. Expression of the Na V 1.2 mutant in a heterologous expression system revealed decreased Na V 1.2 channel function, and cultured pyramidal neurons isolated from Scn2a Δ1898/+ forebrain showed correspondingly reduced voltage-gated Na + channel currents without compensation from other CNS voltage-gated Na + channels. Na + currents in inhibitory neurons were unaffected. Consistent with loss of voltage-gated Na + channel currents, Scn2a Δ1898/+ pyramidal neurons displayed reduced excitability in forebrain neuronal culture and reduced excitatory synaptic input onto the pyramidal neurons in brain slices. Scn2a Δ1898/+ mice displayed several behavioral abnormalities, including abnormal social interactions that reflect behavior observed in humans with ASD and with harboring loss-of-function SCN2A variants. This model and its cellular electrophysiological characterizations provide a framework for tracing how a SCN2A loss-of-function variant leads to cellular defects that result in ASD-associated behaviors.

Frontiers in Neuroscience · Jul 2021

Effects of Multisession Anodal Electrical Stimulation of the Auditory Cortex on Temporary Noise-Induced Hearing Loss in the Rat (opens in a new tab)

Iván Díaz, Ana Cecilia Colmenárez-Raga, David Pérez-González, … Miguel A. Merchán

Abstract

The protective effect of the efferent system against acoustic trauma (AT) has been shown by several experimental approaches, including damage to one ear, sectioning of the olivocochlear bundle (OCB) in the floor of the IV ventricle, and knock-in mice overexpressing outer hair cell (OHC) cholinergic receptors, among others. Such effects have been related to changes in the regulation of the cholinergic efferent system and in cochlear amplification, which ultimately reverse upon protective hearing suppression. In addition to well-known circuits of the brainstem, the descending corticofugal pathway also regulates efferent neurons of the olivary complex. In this study, we applied our recently developed experimental paradigm of multiple sessions of electrical stimulation (ES) to activate the efferent system in combination with noise overstimulation. ABR thresholds increased 1 and 2 days after AT (8–16 kHz bandpass noise at 107 dB for 90 min) recovering at AT + 14 days. However, after multiple sessions of epidural anodal stimulation, no changes in thresholds were observed following AT. Although an inflammatory response was also observed 1 day after AT in both groups, the counts of reactive macrophages in both experimental conditions suggest decreased inflammation in the epidural stimulation group. Quantitative immunocytochemistry for choline acetyltransferase (ChAT) showed a significant decrease in the size and optical density of the efferent terminals 1 day after AT and a rebound at 14 days, suggesting depletion of the terminals followed by a long-term compensatory response. Such a synthesis recovery was significantly higher upon cortical stimulation. No significant correlation was found between ChAT optical density and size of the buttons in sham controls (SC) and ES/AT + 1day animals; however, significant negative correlations were shown in all other experimental conditions. Therefore, our comparative analysis suggests that cochleotopic cholinergic neurotransmission is also better preserved after multisession epidural stimulation.

eLife · May 2021

Corticothalamic gating of population auditory thalamocortical transmission in mouse (opens in a new tab)

Baher A Ibrahim, Caitlin A Murphy, Georgiy Yudintsev, … Daniel A Llano

Abstract

The mechanisms that govern thalamocortical transmission are poorly understood. Recent data have shown that sensory stimuli elicit activity in ensembles of cortical neurons that recapitulate stereotyped spontaneous activity patterns. Here, we elucidate a possible mechanism by which gating of patterned population cortical activity occurs. In this study, sensory-evoked all-or-none cortical population responses were observed in the mouse auditory cortex in vivo and similar stochastic cortical responses were observed in a colliculo-thalamocortical brain slice preparation. Cortical responses were associated with decreases in auditory thalamic synaptic inhibition and increases in thalamic synchrony. Silencing of corticothalamic neurons in layer 6 (but not layer 5) or the thalamic reticular nucleus linearized the cortical responses, suggesting that layer 6 corticothalamic feedback via the thalamic reticular nucleus was responsible for gating stochastic cortical population responses. These data implicate a corticothalamic-thalamic reticular nucleus circuit that modifies thalamic neuronal synchronization to recruit populations of cortical neurons for sensory representations.

International Journal of Molecular Sciences · Apr 2021

Overexpression of Isl1 under the Pax2 Promoter, Leads to Impaired Sound Processing and Increased Inhibition in the Inferior Colliculus (opens in a new tab)

Tetyana Chumak, Diana Tothova, Iva Filova, … Josef Syka

RX5RP2.1BioSigSystem 3BrainWareABR/DPOAEAuditory NeurophysiologySingle Unit
Abstract

The LIM homeodomain transcription factor ISL1 is essential for the different aspects of neuronal development and maintenance. In order to study the role of ISL1 in the auditory system, we generated a transgenic mouse (Tg) expressing Isl1 under the Pax2 promoter control. We previously reported a progressive age-related decline in hearing and abnormalities in the inner ear, medial olivocochlear system, and auditory midbrain of these Tg mice. In this study, we investigated how Isl1 overexpression affects sound processing by the neurons of the inferior colliculus (IC). We recorded extracellular neuronal activity and analyzed the responses of IC neurons to broadband noise, clicks, pure tones, two-tone stimulation and frequency-modulated sounds. We found that Tg animals showed a higher inhibition as displayed by two-tone stimulation; they exhibited a wider dynamic range, lower spontaneous firing rate, longer first spike latency and, in the processing of frequency modulated sounds, showed a prevalence of high-frequency inhibition. Functional changes were accompanied by a decreased number of calretinin and parvalbumin positive neurons, and an increased expression of vesicular GABA/glycine transporter and calbindin in the IC of Tg mice, compared to wild type animals. The results further characterize abnormal sound processing in the IC of Tg mice and demonstrate that major changes occur on the side of inhibition.

eneuro · Apr 2021

Adaptive Response Behavior in the Pursuit of Unpredictably Moving Sounds (opens in a new tab)

José A. García-Uceda Calvo, Marc M. van Wanrooij, A. John Van Opstal

RP2.1System 3Psychoacoustics
Abstract

Although moving sound-sources abound in natural auditory scenes, it is not clear how the human brain processes auditory motion. Previous studies have indicated that, although ocular localization responses to stationary sounds are quite accurate, ocular smooth pursuit of moving sounds is very poor. We here demonstrate that human subjects faithfully track a sound’s unpredictable movements in the horizontal plane with smooth-pursuit responses of the head. Our analysis revealed that the stimulus–response relation was well described by an under-damped passive, second-order low-pass filter in series with an idiosyncratic, fixed, pure delay. The model contained only two free parameters: the system’s damping coefficient, and its central (resonance) frequency. We found that the latter remained constant at ∼0.6 Hz throughout the experiment for all subjects. Interestingly, the damping coefficient systematically increased with trial number, suggesting the presence of an adaptive mechanism in the auditory pursuit system (APS). This mechanism functions even for unpredictable sound-motion trajectories endowed with fixed, but covert, frequency characteristics in open-loop tracking conditions. We conjecture that the APS optimizes a trade-off between response speed and effort. Taken together, our data support the existence of a pursuit system for auditory head-tracking, which would suggest the presence of a neural representation of a spatial auditory fovea (AF).

Neural Plasticity · Apr 2021

Transcriptomic Analysis Reveals an Altered Hcy Metabolism in the Stria Vascularis of the Pendred Syndrome Mouse Model (opens in a new tab)

Wenyue Xue, Yuxin Tian, Yuanping Xiong, … Shankai Yin

RP2.1System 3PA4SigGenRA4ABR/DPOAE
Abstract

Purpose. Slc26a4-/- mice exhibit severer defects in the development of the cochlea and develop deafness, while the underlying mechanisms responsible for these effects remain unclear. Our study was to investigate the potential mechanism linking SLC26A4 deficiency to hearing loss. Materials and Methods. RNA sequencing was applied to analyze the differential gene expression of the stria vascularis (SV) from wildtype and Slc26a4-/- mice. GO and KEGG pathway analysis were performed. Quantitative RT-PCR was applied to validate the expression of candidate genes affected by Slc26a4. ELISA and immunofluorescence technique were used to detect the homocysteine (Hcy) level in serum, brain, and SV, respectively. Results. 183 upregulated genes and 63 downregulated genes were identified in the SV associated with Slc26a4 depletion. Transcriptomic profiling revealed that Slc26a4 deficiency significantly affected the expression of genes associated with cell adhesion, transmembrane transport, and the biogenesis of multicellular organisms. The SV from Slc26a4-/- mice exhibited a higher expression of Bhmt mRNAs, as well as altered homocysteine (Hcy) metabolism. Conclusions. The altered expression of Bhmt results in a dramatic change in multiple biochemical reactions and a disruption of nutrient homeostasis in the endolymph which may contribute to hearing loss of Slc26a4 knockout mouse.

PLOS ONE · Apr 2021

Lack of collagen 6(IV) chain in mice does not cause severe-to-profound hearing loss or cochlear malformation, a distinct phenotype from nonsyndromic hearing loss with COL4A6 missense mutation (opens in a new tab)

Shaoying Tang, Tomoko Yonezawa, Yukihide Maeda, … Toshitaka Oohashi

PA5RP2.1RA16ABR/DPOAE
Abstract

Congenital hearing loss affects 1 in every 1000 births, with genetic mutations contributing to more than 50% of all cases. X-linked nonsyndromic hereditary hearing loss is associated with six loci (DFNX1-6) and five genes. Recently, the missense mutation (c.1771G>A, p.Gly591Ser) in COL4A6 , encoding the basement membrane (BM) collagen α6(IV) chain, was shown to be associated with X-linked congenital nonsyndromic hearing loss with cochlear malformation. However, the mechanism by which the COL4A6 mutation impacts hereditary hearing loss has not yet been elucidated. Herein, we investigated Col4a6 knockout (KO) effects on hearing function and cochlear formation in mice. Immunohistochemistry showed that the collagen α6(IV) chain was distributed throughout the mouse cochlea within subepithelial BMs underlying the interdental cells, inner sulcus cells, basilar membrane, outer sulcus cells, root cells, Reissner’s membrane, and perivascular BMs in the spiral limbus, spiral ligament, and stria vascularis. However, the click-evoked auditory brainstem response analysis did not show significant changes in the hearing threshold of Col4a6 KO mice compared with wild-type (WT) mice with the same genetic background. In addition, the cochlear structures of Col4a6 KO mice did not exhibit morphological alterations, according to the results of high-resolution micro-computed tomography and histology. Hence, loss of Col4a6 gene expression in mice showed normal click ABR thresholds and normal cochlear formation, which differs from humans with the COL4A6 missense mutation c.1771G>A, p.Gly591Ser. Therefore, the deleterious effects in the auditory system caused by the missense mutation in COL4A6 are likely due to the dominant-negative effects of the α6(IV) chain and/or α5α6α5(IV) heterotrimer with an aberrant structure that would not occur in cases with loss of gene expression.

Frontiers in Molecular Neuroscience · Mar 2021

Deletion of BDNF in Pax2 Lineage-Derived Interneuron Precursors in the Hindbrain Hampers the Proportion of Excitation/Inhibition, Learning, and Behavior (opens in a new tab)

Philipp Eckert, Philine Marchetta, Marie K. Manthey, … Marlies Knipper

Abstract

Numerous studies indicate that deficits in the proper integration or migration of specific GABAergic precursor cells from the subpallium to the cortex can lead to severe cognitive dysfunctions and neurodevelopmental pathogenesis linked to intellectual disabilities. A different set of GABAergic precursors cells that express Pax2 migrate to hindbrain regions, targeting, for example auditory or somatosensory brainstem regions. We demonstrate that the absence of BDNF in Pax2-lineage descendants of Bdnf Pax 2 KOs causes severe cognitive disabilities. In Bdnf Pax 2 KOs, a normal number of parvalbumin-positive interneurons ( PV-IN s) was found in the auditory cortex ( AC ) and hippocampal regions, which went hand in hand with reduced PV-labeling in neuropil domains and elevated activity-regulated cytoskeleton-associated protein ( Arc/Arg3.1 ; here: Arc ) levels in pyramidal neurons in these same regions. This immaturity in the inhibitory/excitatory balance of the AC and hippocampus was accompanied by elevated LTP, reduced (sound-induced) LTP/LTD adjustment, impaired learning, elevated anxiety, and deficits in social behavior, overall representing an autistic-like phenotype. Reduced tonic inhibitory strength and elevated spontaneous firing rates in dorsal cochlear nucleus ( DCN ) brainstem neurons in otherwise nearly normal hearing Bdnf Pax 2 KOs suggests that diminished fine-grained auditory-specific brainstem activity has hampered activity-driven integration of inhibitory networks of the AC in functional (hippocampal) circuits. This leads to an inability to scale hippocampal post-synapses during LTP/LTD plasticity. BDNF in Pax2-lineage descendants in lower brain regions should thus be considered as a novel candidate for contributing to the development of brain disorders, including autism.

Veterinary Sciences · Mar 2021

Phenotype of the Aging-Dependent Spontaneous Onset of Hearing Loss in DBA/2 Mice (opens in a new tab)

Min-Soo Seo, Byeonghyeon Lee, Kyung-Ku Kang, … Kil Soo Kim

MF1PA5RP2.1ED1System 3ABR/DPOAE
Abstract

DBA/2 mice are a well-known animal model for hearing loss developed due to intrinsic properties of these animals. However, results on the phenotype of hearing loss in DBA/2 mice have been mainly reported at an early stage in mice aged ≤7 weeks. Instead, the present study evaluated the hearing ability at 5, 13, and 34 weeks of age using DBA/2korl mice. Auditory brainstem response test was performed at 8–32 KHz at 5, 13, and 34 weeks of age, and hearing loss was confirmed to be induced in a time-dependent manner. In addition, histopathological evaluation at the same age confirmed the morphological damage of the cochlea. The findings presented herein are the results of the long-term observation of the phenotype of hearing loss in DBA/2 mice and can be useful in studies related to aging-dependent hearing loss.

Neural Plasticity · Mar 2021

Acoustically Enriched Environment during the Critical Period of Postnatal Development Positively Modulates Gap Detection and Frequency Discrimination Abilities in Adult Rats (opens in a new tab)

Kateryna Pysanenko, Natalia Rybalko, Zbyněk Bureš, … Josef Syka

Abstract

Throughout life, sensory systems adapt to the sensory environment to provide optimal responses to relevant tasks. In the case of a developing system, sensory inputs induce changes that are permanent and detectable up to adulthood. Previously, we have shown that rearing rat pups in a complex acoustic environment (spectrally and temporally modulated sound) from postnatal day 14 (P14) to P28 permanently improves the response characteristics of neurons in the inferior colliculus and auditory cortex, influencing tonotopical arrangement, response thresholds and strength, and frequency selectivity, along with stochasticity and the reproducibility of neuronal spiking patterns. In this study, we used a set of behavioral tests based on a recording of the acoustic startle response (ASR) and its prepulse inhibition (PPI), with the aim to extend the evidence of the persistent beneficial effects of the developmental acoustical enrichment. The enriched animals were generally not more sensitive to startling sounds, and also, their PPI of ASR, induced by noise or pure tone pulses, was comparable to the controls. They did, however, exhibit a more pronounced PPI when the prepulse stimulus was represented either by a change in the frequency of a background tone or by a silent gap in background noise. The differences in the PPI of ASR between the enriched and control animals were significant at lower (55 dB SPL), but not at higher (65-75 dB SPL), intensities of background sound. Thus, rearing pups in the acoustically enriched environment led to an improvement of the frequency resolution and gap detection ability under more difficult testing conditions, i.e., with a worsened stimulus clarity. We confirmed, using behavioral tests, that an acoustically enriched environment during the critical period of development influences the frequency and temporal processing in the auditory system, and these changes persist until adulthood.

Cognition · Mar 2021

Training enhances the ability of listeners to exploit visual information for auditory scene analysis (opens in a new tab)

Huriye Atilgan, Jennifer K. Bizley

Abstract

The ability to use temporal relationships between cross-modal cues facilitates perception and behavior. Previously we observed that temporally correlated changes in the size of a visual stimulus and the intensity in an auditory stimulus influenced the ability of listeners to perform an auditory selective attention task (Maddox, Atilgan, Bizley, & Lee, 2015). Participants detected timbral changes in a target sound while ignoring those in a simultaneously presented masker. When the visual stimulus was temporally coherent with the target sound, performance was significantly better than when the visual stimulus was temporally coherent with the masker, despite the visual stimulus conveying no task-relevant information. Here, we trained observers to detect audiovisual temporal coherence and asked whether this changed the way in which they were able to exploit visual information in the auditory selective attention task. We observed that after training, participants were able to benefit from temporal coherence between the visual stimulus and both the target and masker streams, relative to the condition in which the visual stimulus was coherent with neither sound. However, we did not observe such changes in a second group that were trained to discriminate modulation rate differences between temporally coherent audiovisual streams, although they did show an improvement in their overall performance. A control group did not change their performance between pretest and post-test and did not change how they exploited visual information. These results provide insights into how crossmodal experience may optimize multisensory integration.