Otolaryngology researcher Amanda Lauer discusses how she studies the specialization of the auditory efferent system in bats.
I started out as a researcher about 20 years ago. I was a graduate student sitting hearing Lost in Avian Model that was bred for low frequency song and the bottle was very intriguing because birds normally have the ability to regenerate her cells after damage, this type of bird was unable to well regenerate its hair cells properly and regain normal. Hearing. My lab at Hopkins, however, uses mostly mouse models of age related and noise induced hearing problems. Problems with a little bit work on genetic hearing loss. My lab studies how the brain stem was affected by different from hearing loss on how the feedback pathways projecting from the brain to the ear, play a role in hearing deficits. My lab is especially interested in liking structural changes in the auditory system to behavioral and perceptual deficits like hearing noise difficulties or hyper sensitivity to loud sounds and fitness. We also sometimes do comparative studies using interesting species because my background is in comparative hearing. So we're very interested in species that are exceptionally resistant to aging and hearing loss were primarily interested in understanding basic mechanisms of hearing loss as well as potential strategies to protect against the generation of the auditory pathways and to improve hearing. Rubenstein funding has allowed us to pursue novel research questions about the projections from the brain to the ear, which we call the auditory different or illegal cochlear system. Normally, the system helps to protect against hearing loss, and it facilitates hearing a noise by adjusting the gain in the company through a feedback loop. Sort of like the way a Somerset in the House works. Weakening of these pathways can lead to problems with sound perception, but we're also interested in what circumstances strengthen these pathways. So we've had a really unique opportunity to look at strengthening of these pathways through the Rubenstein funding and Trans Hopkins. John tokens is a really great place to be investigating this pathway because we have some of the world's foremost experts on faculty, and we also have excellent opportunities to collaborate with other labs. Been working with a bad lab to study specializations in the auditory different system. So bats are really interesting for us because they live much longer than other small mammals and their presumed to be resistant to hearing loss throughout their life span, and they rely on a keen sense of hearing to survive because they need a co location to forge for food and to navigate through the world. But a bat that can't here in the wild won't likely survive for a loan. What's really unusual is that in nature there were exposed to hours and hours are very loud sounds from their own vocalizations from other bats. Yet they don't seem to develop hearing loss. These kinds of sounds would cause loss of hearing loss in humans and other species, so we believe they have evolved different specializations to protect against age related and noise induced hearing loss. Those mechanisms are really not very well understood. In that's there are only a few studies. Decades ago, our collaboration with the BAT Lab investigates this enhanced protection against hearing last. The species we worked with seem tohave enhanced auditory, different systems, more cells and larger synapses in the ear. We think that those, um, increased number of cells and the larger synapse synapse is actually allow for better protection after noise exposure and against age related hearing loss. And those specializations might also have the bats filter out irrelevant sounds so they can pay attention to the important sounds that they need for forging a place. Interestingly, we have found that some individuals of one of the species we look at big brown bat actually are tough. The species is native to Maryland. It's very common bat around here, and usually we work with wild cut numbers of the species. But we were able to obtain some captive bred individuals of the species, and it turned out, um, some of them couldn't hear it all. They were completely deaf. They were missing most of the century cells and neurons in their ears. We think that deafness is actually related to inbreeding and other stressors that are increasing susceptibility to deafness, impossibly to deficits. In auditory different system, we plan to perform measurements to assess the status of the auditory appearance and young, very young baths and aging bats. See if this noise resistance and these specializations or president birth, or if they develop over a course of, um, having exposure to loud sounds early in life. The reason we want to look at that is because our recent work with Chlebowski Lab at Johns Hopkins has shown that one branch of that auditory different system literal difference are very plastic, the Pentagon acoustic exposure and by plastic I mean that certain proteins are up regulated in response to Louse town Exposures Way might be able to identify certain conditions that allow us to boost than a beneficial effects of the insurance system, Um, and maybe improve hearing noise or protect against hearing once the idea would be, hopefully that one day we can fight what we learned from animal models to human years. So there's still a lot we don't know about the different system. It's, um, not a very well understood system, even though it's been studied for many decades because it's very complicated system. We want to know things like what spectrum of conditions will result in this plasticity. And is the plasticity diminish with age meaning? Is it possible that just bring tear pathway isn't able to compensate for, um, changing sound conditions, changing sound exposures with age? Our previous work with the Folks lab at Johns Hopkins indicates that the synapses of these auditory different knobs actually move around in the ear of age related hearing loss. We don't really know quite what the effects are of that on hearing last But we think it could either exacerbate the hearing last by turning down the cochlear activity even more where it might actually from some sort of compensatory strategy for protecting sort of what's left in the engineer, the neurons in the engineer that haven't degenerated. We also don't know how well the different neurons are working in cells in the year when sounds were regenerated after damage. You don't even really know if they get wired up properly after the regeneration. So the next phase of the research funding will support us investigating these kinds of exciting questions. That's really important because it's very difficult to get funding from the or other sources for exploratory types of questions and forming new collaborations to get funding from the N. A. You really have to tell the experiments were gonna work out exactly the way you think well and often and studying the system. That's not how things happen. So I'm certain that the experiments that we're going to do, we're going to need to really surprising and interesting discoveries and additional past pursuing the future
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