Bridging the two hemispheres is a bundle of fibers called the corpus callosum.
The two hemispheres communicate with one another across the corpus callosum.
Covering the outermost layer of the cerebrum is a sheet of tissue called the cerebral cortex.
As it is grey in colour, the cerebral cortex is often referred to as grey matter. The wrinkled appearance of the human brain also can be attributed to characteristics of the cerebral cortex. More than two-thirds of this layer is folded into grooves. The grooves increase the brain’s surface area, allowing for inclusion of many more neurons.
The function of the cerebral cortex can be understood by dividing it arbitrarily into zones.
The frontal lobe is responsible for initiating and coordinating motor movements and higher cognitive skills, like problem solving, thinking, planning, and organizing as well as for aspects of personality and emotion.
The parietal lobe is involved with sensory processes, attention, and language.
Damage to the right side of the parietal lobe can result in difficulty navigating spaces, even familiar ones.
If the left side is injured, the ability to understand spoken and written language may be impaired.
The occipital lobe helps process visual information including the recognition of shapes and colors.
The temporal lobe helps to process auditory information and integrate information from the other senses. Neurosciences believe that the temporal lobe has a role to play in short-term memory through the hippocampus and in learned emotional responses through the amygdala. All of these structures make up the fore-brain. Other key parts of the fore-brain include the basal ganglia, which are cerebral nuclei deep in the cerebral cortex, the thalamus and the hypothalamus.
The cerebral nuclei help coordinate muscle movements and reward useful behaviors. The thalamus passes most sensory information on to the cerebral cortex after helping to prioritize it. The hypothalamus is the control center for appetites, defensive and reproductive behaviors and sleep-wakefulness.
The midbrain consists of two pairs of small hills called colliculi. These collections of neurons play a critical role in visual and auditory reflexes and in relaying this type of information to the thalamus. The midbrain also has clusters of neurons that regulate activity in widespread parts of the central nervous system and are thought to be important for reward mechanisms and mood.
The hindbrain includes the pons and the medulla oblongata, which control respiration, heart rhythms, and blood glucose levels.
Another part of the hindbrain is the cerebellum which, like the cerebrum, also has two hemispheres. The cerebellum’s two hemispheres help control movement and cognitive processes that require precise timing. They also play an important role in Pavlovian learning.
The spinal cord is the extension of the brain through the vertebral column where it receives sensory information from all parts of the body. The spinal chord uses this information for reflex responses to pain. It also generates impulses in the nerves that control the muscles and the viscera, both through reflex activities and through voluntary commands from the cerebrum.