Concussion is a complex pathophysiological process and further study is required to fully understand it.
Undoubtedly there are changes to the normal biochemical and electrical processes within the nerve cells of the brain which interrupts their normal function
Evidence suggest the concussed brain is less responsive to usual neural activation and when premature cognitive or physical activity occurs before full recovery the brain my be vulnerable to prolonged dysfunction
Giza, C. & Hovda, D. The new metabolic cascade of concussion. Neurosurgery. 2014 75(4): S24-S33