A cortical injury model in a non-human primate to assess execution of reach and grasp actions: implications for recovery after traumatic brain injury

Background: Technological advances in developing experimentally controlled models of traumatic brain injury (TBI) are prevalent in rodent models and these models have proven invaluable in characterizing temporal changes in brain and behavior after trauma. To date no long-term studies in non-human primates (NHPs) have been published using an experimentally controlled impact device to follow behavioral performance over time. New method: We have employed a controlled cortical impact (CCI) device to create a focal contusion to the hand area in primary motor cortex (M1) of three New World monkeys to characterize changes in reach and grasp function assessed for 3 months after the injury. Results: The CCI destroyed most of M1 hand representation reducing grey matter by 9.6 mm(3), 12.9 mm(3), and 15.5 mm(3) and underlying corona radiata by 7.4 mm(3), 6.9 mm(3), and 5.6 mm(3) respectively. Impaired motor function was confined to the hand contralateral to the injury. Gross hand-use was only mildly affected during the first few days of observation after injury while activity requiring skilled use of the hand was impaired over three months. Comparison with existing method(s): This study is unique in establishing a CCI model of TBI in an NHP resulting in persistent impairments in motor function evident in volitional use of the hand. Conclusions: Establishing an NHP model of TBI is essential to extend current rodent models to the complex neural architecture of the primate brain. Moving forward this model can be used to investigate novel therapeutic interventions to improve or restore impaired motor function after trauma.

Automated summary

This study utilized a controlled cortical impact device to induce a focal contusion in the hand area of the primary motor cortex in three New World monkeys and assessed changes in reach and grasp function over 3 months post-injury. Results showed significant reductions in grey matter and corona radiata in the hand representation area, with impaired motor function affecting mainly the contralateral hand, and skilled hand activity being impaired over the three-month period.