How Light Aversion Affects Grooming in a Mouse Model of Traumatic Brain Injury

Abstract

Record ID: 216

Award(s): Excellence in Research Mentoring; Excellence in Research Communication

Student Major: Neuroscience

Project Advisor: Nathan Evanson

Abstract: Every year 2.8 million Americans endure a traumatic brain injury (TBI), with 68% reporting visual dysfunction and 55% reporting photophobia. Photophobia increases stress levels in response to light, but little research has been done to assess TBI-induced photophobia in animal models. In mice, the cephalocaudal progression is an instinctive behavior that is used to reduce stress, which is expected when experiencing discomfort. This progression includes grooming of the paws, head, and body in that order. This can be divided and measured as body versus rostral grooming, where an increase in rostral grooming may be a result of light aversion as the mouse is trying to cover their eyes or relieve discomfort. Following a TBI, we hypothesize that damage to photoreceptor cells increases photophobia, which increases rostral grooming and impairs the cephalocaudal progression. To establish a baseline of visual function and grooming behavior before injury, adult male C57bl/6J mice were assessed in our optokinetic device, which was adapted to produce an aversive visual environment. This aversive environment utilized increasing light intensities (80 lux, 400 lux, 1100 lux, and 3200 lux) and a spinning drum. Mice incurred a closed-head, weight-drop TBI and were tested 2, 7, 21, and 35 days post injury. Grooming patterns were recorded for the cephalocaudal progression and time spent on rostral versus body grooming. By measuring the grooming patterns of mice following TBI, we can determine light aversion and visual deficits caused by impact to the optic chiasm, which may correlate to TBI-induced photophobia in humans.