A primitve reflex is one which gives gave for a more mature movement of the body to occur as the CNS matures. Primitive reflxes in a nweborn allow for movement, feeding. Once more development occurs, primitive reflex gives way for a refined movement to take place.

Site of lesion in atonic CP would be in the cortex, cerebellum or basal ganglia. If it remains atonic, it is cerebellum. If it evolves into dystonia or choreoathetosis, it is basal ganglia and if it becomes spastic it is cortex and pyramidal tracts.
Seizures occurs in hypoglycemia,hypocalcemia and hypoxic ischemic encephalopathy due to ischemia and hypoxia leading to decreased substrate to the brain leading to lower threshold of electrical activity and seizure.