 The next morning , Jenner shows the group the clinical results of Test Subject 19 , a person ( later announced to be his wife ) who was bitten by a walker and volunteered to be observed as the infection progressed . The time @-@ lapse MRI video demonstrates the disease attacking the brain , similar to meningitis , ultimately killing the victim . Brain activity is restarted a few hours later , simultaneously reanimating the body to mere basic functions . Jenner explains that the brain stem reanimates anywhere from a few minutes to 8 hours after death , and adds that the conscious human traits do not return . 
