The brain has four lobes: frontal, parietal, temporal, and occipital, according to the skull bones covering these areas. Knowing that the lobes are named after bones gives perspective on the divisions. They are based not on functional neurobiology but on bone biology. The lobes form pairs in the hemispheres of the brain. The hemispheres are integrated through the corpus callosum, a tract with several hundred million nerve fibers, where posterior (toward the back) fibers connect the parietal lobes, while mid and anterior (toward the front) fibers connect the visual, motor, and somatosensory (touch and sensation) areas.
Epilepsy has occasionally been dealt with by cutting callosal fibers to reduce interhemispheric cross-talk. Neuropsychologist Michael Gazzaniga (1939-) has studied acallosals, together with neurosurgeon Roger Sperry (1913-1994) (Wolman 2012). Acallosals experience reduced epileptic symptoms, but their hemispheres can act in oddly independent ways. Acallosals seemingly go about their daily affairs as usual. Yet changes in cognition and consciousness can be experimentally demonstrated. We will get back to acallosals when we explore the unity of consciousness as a topic. Let us now examine the different lobes of the brain. We start with the frontal lobes. After we have examined these late evolutionary structures, we will explore the older core.