Despite growing evidence that childhood represents a major risk period for mild traumatic brain injury (mTBI) from sports-related concussions, motor vehicle accidents, and falls, a reliable animal model of mTBI had previously not been developed for this important aspect of development. The modified weight-drop technique employs a glancing impact to the head of a freely moving rodent transmitting acceleration, deceleration, and rotational forces upon the brain. When applied to juvenile rats, this modified weight-drop technique induced clinically relevant behavioural outcomes that were representative of post-concussion symptomology. The technique is a rapidly applied procedure with an extremely low mortality rate, rendering it ideal for high-throughput studies of therapeutics. In addition, because the procedure involves a mild injury to a closed head, it can easily be used for studies of repetitive brain injury. Owing to the simplistic nature of this technique, and the clinically relevant biomechanics of the injury pathophysiology, the modified weight-drop technique provides researchers with a reliable model of mTBI that can be used in a wide variety of behavioural, molecular, and genetic studies.

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Childhood is one the highest risk periods for experiencing a mild traumatic brain injury (mTBI) from sports-related concussions, motor vehicle accidents, and falls. In addition, many children experience lingering symptomology (post-concussion syndrome) from these closed head injuries. Although the negative sequel of mTBI has been described, a clinically reliable animal model of mild pediatric brain injury has not. The purpose of this study was to examine the validity of a modified weight-drop technique as a model for the induction of mTBI/concussion in juvenile rats following a single impact. Male and female rats (P30) were exposed to a single mTBI or a sham injury followed by a behavioral test battery. Juvenile rats who experienced a single mTBI displayed significant motor/balance impairments when tested on the beam walking task and in the open field, as well as deficits of executive functioning as measured with the novel context mismatch task and the probe trial of the Morris water task. In addition, both male and female rats showed depression-like behavior in the forced swim task, with male rats also exhibiting decreased anxiety-related behaviors in the elevated plus maze. The results from this study suggest that the modified weight-drop technique induces a clinically relevant behavioral phenotype in juvenile rats, and may provide researchers with a reliable animal model of mTBI/concussion from which clinical therapeutic strategies could be developed.