Repeated mild traumatic brain injuries impair visual discrimination learning in adolescent mice.

Cognitive deficits following a mild traumatic brain injury (mTBI) are common and are associated with learning deficits in school-age children. Some of these deficits include problems with long-term memory, working memory, processing speeds, attention, mental fatigue, and executive function. Processing speed deficits have been associated with alterations in white matter, but the underlying mechanisms of many of the other deficits are unclear. Without a clear understanding of the underlying mechanisms we cannot effectively treat these injuries. The goal of these studies is to validate a translatable touchscreen discrimination/reversal task to identify deficits in executive function following a single or repeated mTBIs. Using a mild closed skull injury model in adolescent mice we were able to identify clear deficits in discrimination learning following repeated injuries that were not present from a single mTBI. The repeated injuries were not associated with any deficits in motor-based behavior but did induce a robust increase in astrocyte activation. These studies provide an essential platform to interrogate the underlying neurological dysfunction associated with these injuries.