He at least has an amygdala and the center of the spinal core because he must have a heart because we did see him bleed once (not from a bullet, for the record), and he appears to breath involuntarily, unless his amygdala, through the mysteries of cognitive plasticity allows him to breath manually, which would explain why everything seems like a lot of effort for him. He might just be an amygdala floating in cerebral fluid.