‘I’m too freaked out to hear you!’ How early-life stress affects auditory perception and the brain

[Past Projects]

Merri Rosen PhD, Kate Hardy MS, and Matthew Sunthimer BS

It’s well-known that hearing problems in kids may cause later trouble with understanding complex sounds, such as rapid speech in a place with a lot of background noise. But our lab is the first to show that stress during development can cause similar problems. We’re funded by the National Institutes of Health to study the neural changes that can cause these stress-induced deficits in auditory perception. Many labs have studied the effects of early life stress (ELS) on the development of brain regions responsible for attention, learning, and related psychopathologies. However, nobody has examined whether auditory information is being encoded properly before it even reaches these higher-level brain regions. This is important, because children who grow up in low-socioeconomic, high stress environments are at risk for later problems with speech perception. Discovering what is going wrong mechanistically will help prevent and remediate these problems.
Our lab has shown that ELS affects auditory perception and neural activity in brain regions that encode sound. It turns out that ELS may be a particular problem when kids have ear infections that cause intermittent hearing loss – our data show that early hearing loss and stress together are much worse than either one alone! We use an animal model (the Mongolian gerbil) to study how early-life stress and hearing loss affect the perception of rapid changes in sound, and the underlying neural mechanisms. The Mongolian gerbil is a well-established auditory model, because gerbils hear well at frequencies that humans use, unlike mice or rats. Several projects are available in our lab: Seeing stress in the brain!
  • Background: Auditory perceptual problems from ELS and hearing loss may arise from changes in certain molecules that determine how neural circuits are wired during development. Measuring these elements will clarify whether deficits from ELS and hearing loss arise through similar or disparate mechanisms.
  • Objectives: To investigate changes in specific molecular markers within the auditory pathway across development. These changes are indicative of alterations in functionality and plasticity across development.
  • Methods: The effects of early stress and hearing loss on the brain will be identified using immunohistochemistry techniques which tag specific neuronal proteins with fluorescent markers. These markers can be visualized and quantified under a fluorescent microscope.
What stresses out our animals? Perception in action: Testing the limits of hearing
  • Background: Historically, mice and rats have been primarily used in stress research. To study stress in an established animal model of hearing, we are developing a new model of stress in the Mongolian gerbil.
  • Objective: To characterize the effects of the limited bedding model (LBM) on emotion, cognition, and auditory perception.
  • Methods: Implementation of the LBM model uses video recordings of breeder cages in a bedding-scarce environment. A combination of behavior tracking software and manual hand scoring of recordings will be used to characterize the new model. Various biomarkers will be measured to quantify stress markers, such as blood corticosterone and body weight. Effects on anxiety and cognition will be measured by standardized behavioral tests. Deficits in auditory perception will be measured using operant conditioning to train animals to respond when they discriminate between behaviorally-relevant sounds.
Livestreaming real-time brain activity: The Miniscope
  • Background: Our lab is working to set up an optical Miniscope, which allows us to visualize neuronal activity across a population of cells in real time, in freely-moving behaving animals.
  • Objectives: To contribute to getting this leading-edge technology set up in the lab.
  • Methods: Various skills will be learned while working closely alongside a lab member.
Benefits to student:
  • Receive training in experimental techniques used widely across research fields in biology and neuroscience
  • Learn how to apply critical thinking to big problems in neuroscience
  • Opportunity to join our lab as a PhD student or technician
Learn more about the Rosen lab.