Our knowledge of the hearing abilities of frogs and toads is largely defined by work with a few well-studied species. One way to further advance comparative work on anuran hearing would be greater use of minimally invasive electrophysiological measures, such as the auditory brainstem response (ABR). This study used the ABR evoked by tones and clicks to investigate hearing in Cope's gray treefrog (Hyla chrysoscelis). The objectives were to characterize the effects of sound frequency, sound pressure level, and subject sex and body size on ABRs. The ABR in gray treefrogs bore striking resemblance to ABRs measured in other animals. As stimulus level increased, ABR amplitude increased and latency decreased, and for responses to tones, these effects depended on stimulus frequency. Frequency-dependent differences in ABRs were correlated with expected differences in the tuning of two sensory end organs in the anuran inner ear (the amphibian and basilar papillae). The ABR audiogram indicated two frequency regions of increased sensitivity corresponding to the expected tuning of the two papillae. Overall, there was no effect of subject size and only small effects related to subject sex. Together, these results indicate the ABR is an effective method to study audition in anurans.

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Noise exposure is one of the most common causes of hearing loss and peripheral damage to the auditory system. A growing literature suggests that the auditory system can compensate for peripheral loss through increased central neural activity. The current study sought to investigate the link between noise exposure, increases in central gain, synaptic reorganization, and auditory function. All axons of the auditory nerve project to the cochlear nucleus, making it a requisite nucleus for sound detection. As the first synapse in the central auditory system, the cochlear nucleus is well positioned to respond plastically to loss of peripheral input. To investigate noise-induced compensation in the central auditory system, we measured auditory brainstem responses (ABRs) and auditory perception and collected tissue from mice exposed to broadband noise. Noise-exposed mice showed elevated ABR thresholds, reduced ABR wave 1 amplitudes, and spiral ganglion neuron loss. Despite peripheral damage, noise-exposed mice were hyperreactive to loud sounds and showed nearly normal behavioral sound detection thresholds. Ratios of late ABR peaks (2–4) relative to the first ABR peak indicated that brainstem pathways were hyperactive in noise-exposed mice, while anatomical analysis indicated there was an imbalance between expression of excitatory and inhibitory proteins in the ventral cochlear nucleus. The results of the current study suggest that a reorganization of excitation and inhibition in the ventral cochlear nucleus may drive hyperactivity in the central auditory system. This increase in central gain can compensate for peripheral loss to restore some aspects of auditory function.

We developed and tested Passport to Wellness (PtW), a client-centered intervention to improve engagement in HIV/STI prevention and services to improve social determinants of health among Black men who have sex with men (BMSM) using incentives and peer support. We assessed PtW's impact on HIV/STI screening and pre/post-exposure prophylaxis (PrEP/PEP) knowledge/uptake using a randomized trial that compared the full intervention to one lacking peer support. We compared changes within groups surveyed at baseline and 6 months. We enrolled 80 eligible BMSM, among 399 screened. Among retained participants (34 peer-supported; 27 comparison), overall increases were observed in HIV (30% to 87%; p < .001) and STI (28% to 80%; p < .001) testing within the prior 6 months, as well as in PrEP and PEP awareness, and PrEP use. Statistically significant between group differences were not observed. Tailored prevention planning, incentives, and addressing social determinants may help move Black MSM along the HIV prevention continuum.

An important and necessary step in the analysis of any communication system involves quantitative descriptions of how signals vary at multiple levels of organization (e.g., species, populations, individuals). Such descriptions provide a basis for generating testable predictions about the functions of signals and their specific physical properties in different behavioral contexts. Here, we report results from acoustical and statistical analyses of the advertisement calls of the boreal chorus frog, Pseudacris maculata. In addition to characterizing measures of central tendency and dispersion for our study population, we assess how calls encode potentially relevant information in the contexts of sexual selection and social recognition. Specifically, we describe the relationships between call properties and both body size and condition, and relate these findings to predictions about female mate choice and male‐male competition. We also make predictions about the shapes of female preference functions based on analyses of the patterns of within‐individual variation in call properties. Findings from multivariate analyses of advertisement calls are used to generate testable predictions about the potential for these signals to function in social recognition. We also discuss our results in relation to wildlife conservation and relevant studies of geographic variation.

SUMMARYPlasticity of thalamocortical (TC) synapses is robust during early development and becomes limited in the adult brain. We previously reported that a short duration of deafening strengthens TC synapses in the primary visual cortex (V1) of adult mice. Here, we demonstrate that deafening restores NMDA receptor (NMDAR)-dependent long-term potentiation (LTP) of TC synapses onto principal neurons in V1 layer 4 (L4), which is accompanied by an increase in NMDAR function. In contrast, deafening did not recover long-term depression (LTD) at TC synapses. Potentiation of TC synapses by deafening is absent in parvalbumin-positive (PV+) interneurons, resulting in an increase in feedforward excitation to inhibition (E/I) ratio. Furthermore, we found that a brief duration of deafening adult mice recovers rapid ocular dominance plasticity (ODP) mainly by accelerating potentiation of the open-eye responses. Our results suggest that cross-modal sensory deprivation promotes adult cortical plasticity by specifically recovering TC-LTP and increasing the E/I ratio.

Introduction:Sex differences in brain biochemistry, physiology, structure, and function have been gaining increasing attention in the scientific community. Males and females can have different responses to medications, diseases, and environmental variables. A small number of the approximately 7500 studies of noise-induced hearing loss (NIHL) have identified sex differences, but the mechanisms and characterization of these differences have not been thoroughly studied. The National Institutes of Health (NIH) issued a mandate in 2015 to include sex as a biological variable in all NIH-funded research beginning in January 2016.Materials and Methods:In the present study, the representation of sex as a biological variable in preclinical and basic studies of NIHL was quantified for a 5-year period from January 2011 to December 2015 prior to the implementation of the NIH mandate.Results:The analysis of 210 basic and preclinical studies showed that when sex is specified, experiments are predominantly performed on male animals.Discussion:This bias is present in studies completed in the United States and foreign institutions, and the proportion of studies using only male participants has actually increased over the 5-year period examined.Conclusion:These results underscore the need to invest resources in studying NIHL in both sexes to better understand how sex shapes the outcomes and to optimize treatment and prevention strategies.

Introduction: It is estimated over 466 million people worldwide have disabling hearing loss, and untreated hearing loss is associated with poorer health outcomes. The influence of sex as a biological variable on hearing loss is not well understood, especially for differences in underlying mechanisms which are typically elucidated through non-clinical research. Although the inclusion of sex as a biological variable in clinical studies has been required since 1993, sex reporting has only been recently mandated in National Institutes of Health funded non-clinical studies. Objective: This article reviews the literature on recent non-clinical and clinical research concerning sex-based differences in hearing loss primarily since 1993, and discusses implications for knowledge gaps in the translation from non-clinical to clinical realms. Conclusions: The disparity between sex-based requirements for non-clinical versus clinical research may inhibit a comprehensive understanding of sex-based mechanistic differences. Such disparities may play a role in understanding and explaining clinically significant sex differences and are likely necessary for developing robust clinical treatment options.