The lower parts of the brain function primarily in Survival, whereas the outer layer of the brain functions mainly in thought. The medulla oblongata is the lower half of the brainstem continuous with the spinal cord. The medulla contains the cardiac, respiratory, vomiting and vosomotor centres dealing with heart rate, breathing and blood pressure. The outer layer which is the space between the two hemispheres is the longitudinal fissure. The corpus callosum connects two sides and transfers signals from one side of the brain to another.