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Comparative micromechanics of bushcricket ears with and without a specialized auditory fovea region in the crista acustica.

ABSTRACT: In some insects and vertebrate species, the specific enlargement of sensory cell epithelium facilitates the perception of particular behaviourally relevant signals. The insect auditory fovea in the ear of the bushcricket Ancylecha fenestrata (Tettigoniidae: Phaneropterinae) is an example of such an expansion of sensory epithelium. Bushcricket ears developed in convergent evolution anatomical and functional similarities to mammal ears, such as travelling waves and auditory foveae, to process information by sound. As in vertebrate ears, sound induces a motion of this insect hearing organ (crista acustica), which can be characterized by its amplitude and phase response. However, detailed micromechanics in this bushcricket ear with an auditory fovea are yet unknown. Here, we fill this gap in knowledge for bushcricket, by analysing and comparing the ear micromechanics in Ancylecha fenestrata and a bushcricket species without auditory fovea (Mecopoda elongata, Tettigoniidae: Mecopodinae) using laser-Doppler vibrometry. We found that the increased size of the crista acustica, expanded by a foveal region in A. fenestrata, leads to higher mechanical amplitudes and longer phase delays in A. fenestrata male ears. Furthermore, area under curve analyses of the organ oscillations reveal that more sensory units are activated by the same stimuli in the males of the auditory fovea-possessing species A. fenestrata. The measured increase of phase delay in the region of the auditory fovea supports the conclusion that tilting of the transduction site is important for the effective opening of the involved transduction channels. Our detailed analysis of sound-induced micromechanics in this bushcricket ear demonstrates that an increase of sensory epithelium with foveal characteristics can enhance signal detection and may also improve the neuronal encoding.

SUBMITTER: Scherberich J

PROVIDER: S-EPMC7329045 | biostudies-literature | 2020 Jun

REPOSITORIES: biostudies-literature

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Comparative micromechanics of bushcricket ears with and without a specialized auditory fovea region in the crista acustica.

Scherberich Jan J Taszus Roxana R Stoessel Alexander A Nowotny Manuela M

Proceedings. Biological sciences 20200624 1929

In some insects and vertebrate species, the specific enlargement of sensory cell epithelium facilitates the perception of particular behaviourally relevant signals. The insect auditory fovea in the ear of the bushcricket <i>Ancylecha fenestrata</i> (Tettigoniidae: Phaneropterinae) is an example of such an expansion of sensory epithelium. Bushcricket ears developed in convergent evolution anatomical and functional similarities to mammal ears, such as travelling waves and auditory foveae, to proce ...[more]

PMID: 32576108

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Project description:ObjectivesTo determine whether suprathreshold measures of auditory function, such as distortion-product otoacoustic emissions (DPOAEs) and auditory brainstem responses (ABRs), are correlated with noise exposure history in normal-hearing human ears. Recent data from animal studies have revealed significant deafferentation of auditory nerve fibers after full recovery from temporary noise-induced hearing loss. Furthermore, these data report smaller ABR wave I amplitudes in noise-exposed animal ears when compared with non-noise-exposed control animals or prenoise exposure amplitudes in the same animal. It is unknown whether a similar phenomenon exists in the normal-hearing, noise-exposed human ear.DesignThirty normal-hearing human subjects with a range of noise exposure backgrounds (NEBs) participated in this study. NEB was quantified by the use of a noise exposure questionnaire that extensively queried loud sound exposure during the previous 12 months. DPOAEs were collected at three f2s (1, 2, and 4 kHz) over a range of L2s. DPOAE stimulus level began at 80 dB forward-pressure level and decreased in 10 dB steps. Two-channel ABRs were collected in response to click stimuli and 4 kHz tone bursts; one channel used an ipsilateral mastoid electrode and the other an ipsilateral tympanic membrane electrode. ABR stimulus level began at 90 dB nHL and was decreased in 10 dB steps. Amplitudes of waves I and V of the ABR were analyzed.ResultsA statistically significant relationship between ABR wave I amplitude and NEB was found for clicked-evoked ABRs recorded at a stimulus level of 90 dB nHL using a mastoid recording electrode. For this condition, ABR wave I amplitudes decreased as a function of NEB. Similar systematic trends were present for ABRs collected in response to clicks and 4 kHz tone bursts at additional suprathreshold stimulation levels (≥70 dB nHL). The relationship weakened and disappeared with decreases in stimulation level (≤60 dB nHL). Similar patterns were present for ABRs collected using a tympanic membrane electrode. However, these relationships were not statistically significant and were weaker and more variable than those collected using a mastoid electrode. In contrast to the findings for ABR wave I, wave V amplitude was not significantly related to NEB. Furthermore, there was no evidence of a systematic relationship between suprathreshold DPOAEs and NEB.ConclusionsA systematic trend of smaller ABR wave I amplitudes was found in normal-hearing human ears with greater amounts of voluntary NEB in response to suprathreshold clicks and 4 kHz tone bursts. These findings are consistent with the data from previous work completed in animals, where the reduction in suprathreshold responses was a result of deafferentation of high-threshold/low-spontaneous rate auditory nerve fibers. These data suggest that a similar mechanism might be operating in human ears after exposure to high sound levels. However, evidence of this damage is only apparent when examining suprathreshold wave I amplitude of the ABR. In contrast, suprathreshold DPOAE level was not significantly related to NEB. This was expected, given noise-induced auditory damage findings in animal ears did not extend to the outer hair cells, the generator for the DPOAE response.

Project description:Background & aimsCovert hepatic encephalopathy (CHE) impairs quality of life (QOL) and can be difficult to diagnose. Patient-administered methods that do not require specialized tests or equipment might increase rates of detection. We performed a longitudinal study to determine whether demographic data and responses to a validated QOL questionnaire, the Sickness Impact Profile (SIP), can identify patients with CHE.MethodsPatients with cirrhosis without prior overt HE were recruited from outpatient liver clinics at the Virginia Commonwealth University Medical Center, from August 2008 through February 2012. We performed cognitive tests on 170 patients (mean age, 55 y; mean model for end-stage liver disease score, 9; 50% with hepatitis C-associated and 11% with alcohol-associated cirrhosis). Patients also were given the SIP questionnaire (136 questions on 12 QOL topics, requiring a yes or no answer) at enrollment, at 6 months, and at 12 months. The proportion of patients that responded "yes" to each question was compared between those with and without CHE. Patient variables (noncognitive), demographics (age, education, sex, alcoholic etiology), and SIP questions that produced different responses between groups were analyzed by logistic regression and receiver operating characteristic analyses.ResultsBased on cognitive test results, 93 patients (55%) had CHE when the study began. They had a higher proportion of "yes" responses to 54 questions on the SIP questionnaire, across all categories. We developed a formula to identify patients with CHE based on age, sex, and responses to 4 SIP questions (a SIP CHE score). Baseline SIP CHE scores greater than 0 identified patients with CHE with 80% sensitivity and 79% specificity. Of the 98 patients who returned for the 6-month evaluation, 50% had CHE (the SIP CHE identified these patients with 88% sensitivity). Of the 50 patients who returned for the 12-month evaluation, 32% had CHE (the SIP CHE score identified these patients with 81% sensitivity).ConclusionsWe developed a system to identify patients with CHE based on age, sex, and responses to 4 SIP questions; this formula identified patients with CHE with more than 80% sensitivity over a 12-month period after the initial enrollment. Patient-administered CHE screening strategies that do not include specialized tests could increase the detection of CHE and improve therapy.

Project description:Background We believe that our experience with patients presenting with Coats disease and macular sparing should be shared with our colleagues. We would like to show the effect of posture and prompt intervention in cases with fovea-threatening and/or fovea-involving peripheral Coats disease (FTPCD). This association has been poorly debated in our specialty and literature. We call the attention for the unexpexted scenario of observing the lost of the fovea during some types of traditional and prompt interventional treatments of these cases with previous 20/20 vision (something that we have been studying and observing for many years). In order to publish our best representative cases, we have chosen 8 Brazilian patients (age range, 7–62 years; 5 male) with FTPCD. All patients underwent multimodal imaging and different treatments (observation, sleep-posture repositioning, laser, intraocular steroids, and/or anti-vascular endothelial growth factor therapy). All patients, initially, informed to adopt a sleeping lateral-down position, favoring exudation shifting to the fovea pre-treatment. Most promptly-treated patients in this way (n = 4), developed subretinal fluid and exudates in the macula and some had irreversible central visual loss (n = 3). Patients with recent fovea-involving exudation who changed postural sleep position (to protect the foveal area) before and during treatment fared better, with some preserved central vision and an intact fovea (n = 5). The fundus status was correlated with the gravitational effects of posture before and after treatment. Despite prepared as an observational/interventional study, with a small number of cases, the most difficult part is documenting the sleep position of these patients and its influence in the outcomes as there is not good way to prove how well or poorly the positioning occurred in our cases. Finally, we also intended to call the attention to the fact that Coats disease must be studied in all its clinical stage variants and not only seen as a potential blinding and incurable ocular disease. Case presentation This study is a retrospective and/or interventional analysis of eight cases with a less severe clinical variant of classic Coats disease that we refer to as fovea-threatening and fovea-involving peripheral Coats disease (FTPCD). All cases were unilateral with no systemic disease or family history of Coats disease. The bilateral anterior segment and intraocular pressure were normal in all patients. The characteristics of all patients are shown in the Table. Conclusion The funduscopic features of FTPCD are fundamental to disease understanding and optimal management. Habitual posturing may affect the fundus morphologic features of retinal exudation as observed in all current patients with exudative peripheral Coats disease. When sleep habitual posture is not observed in patients with FTPCD, the effects of prompt invasive treatments can cause rapid visual loss because of foveal subretinal pooling of exudates post-treatment. Initial vigilant adjusting of the habitual sleep posture for several patients with FTPCD, before the indication of traditional invasive treatments (laser and/or pharmacologic medications) can result in improved vision and fundoscopic morphologic features. Supplementary Information The online version contains supplementary material available at 10.1186/s40942-022-00382-4.

Dataset Information

Comparative micromechanics of bushcricket ears with and without a specialized auditory fovea region in the crista acustica.

Publications

Comparative micromechanics of bushcricket ears with and without a specialized auditory fovea region in the crista acustica.

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