The corpus callosum is a rich band of axons which project from one hemisphere to another. Through this structure, information is transmitted from one side of the neocortex to the other. It is the main pathway between the two hemispheres of the brain. The olfactory cortex is, evolutionarily speaking, the oldest part of the mammalian brain. This part of the brain, which projects towards the limbic system, is responsible for our sense of smell.
Some scientists believe that the mammalian neocortex evolved from the olfactory cortex.
The neocortex is typically divided into four lobes. There are two hemispheres. In there brain, all structures are duplicated in the two hemispheres with the exception of the pineal gland . There is two of everything except the pineal gland. The frontal lobe is located right in front of very deep fissure known as the central sulcus , also called the Roland fissure or the central fissure .