Anxiety-like behaviour in mice after mild repetitive head impacts during the subacute phase.

Traumatic brain injury (TBI) is a major health concern in the current population. Animal models are increasingly important for identifying early neurobehavioural changes associated with mild to severe as well as repetitive brain injuries. In this study, we analysed behavioural changes in a mouse model of repetitive mild TBI using unbiased quantification metrics. Our approach enabled automated markerless pose estimation of thigmotaxis together with spatial working memory and locomotor activity assessments specifically during the scarcely-studied subacute phase after brain injury. We found that animals exposed to repetitive mild head impacts developed anxiety-like behaviour, manifested by avoidance of the central zone and increased thigmotaxis in the open field test, while maintaining total distance travelled compared to the control group. However, analysis of exploratory behaviour and spatial working memory in the Y-maze, along with assessment of sensorimotor coordination and balance using rotarod tests, revealed no significant difference between the TBI and control groups. These findings suggest that repetitive mTBI is associated with selective anxiety-like behaviour during the subacute phase after brain injury, without detectable motor or cognitive deficits, reflecting the early affective symptomatology frequently reported in clinical populations with mTBI.