Poster Session 2 - B24
1,2Miranda Mellerup, 2Lisa Gazdzinski, 2,3John Sled, 1,2Anne Wheeler
1 Department of Physiology, University of Toronto; 2 Neurosciences & Mental Health, Hospital for Sick Children; 3 Department of Medical Biophysics, University of Toronto
Mild traumatic brain injury (mTBI), which includes concussion, causes highly variable physical, cognitive, and behavioural symptoms that are most often transient; however, 10-15% of patients experience persistent symptoms. It is not known what differentiates those who recover quickly from mTBI from those who do not. The objective of this study was to describe the time course of behavioural impairment following mTBI in a mouse model of concussive injury. Mild TBI was induced in mice using a closed-skull Controlled Cortical Impact model, and behavioural assessments were conducted at an acute (3 days) and chronic (6 weeks) delay post-injury to characterize the time course of impairment. At each time-point, the open field and light/dark tests were used to assess anxiety-like behaviours, the tail suspension test was used to assess depressive-like behaviours, the Y maze was used to assess working memory, and the pre-pulse inhibition test to assess sensorimotor gating. It was found that mTBI mice spent significantly more time in the centre of the arena within the first 5 minutes of the open field test compared to shams across time-points. In the tail suspension test, mTBI mice showed increased mobility compared to shams at the acute time-point. mTBI mice had significantly fewer successful novel arm transitions in the Y maze compared to shams at both time-points. There were no differences between groups in the light/dark test and in the pre-pulse inhibition test. These results reveal an unexpected phenotype whereby mTBI mice displayed fewer anxiety-like and depressive-like behaviours after injury, however these mice appear to have memory deficits that persist over time.