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The primary cortex constitutes several different regions of the outer gray layer of tissue in the human brain that are responsible for higher brain functions involving mostly sensory input processing. These include the primary auditory, visual, and somatosensory cortex regions responsible for interpreting sound, vision, and tactile sensory information, as well as the primary gustatory and olfactory cortex regions that interpret taste and odor senses. Higher brain functions controlled by primary cortex sections of the brain also include the orbitofrontal cortex which regulates emotional responses and controls rage, as well as the primary motor cortex that controls body movement.
Each cortical region of the brain receives sensory information from either other portions of the brain, other parts of the human nervous system, or organs, and interprets their meaning. The primary cortex regions for the senses of sight, smell, and sound are fairly small regions of the entire brain overall, and are each located in distinctly different areas. The visual cortex is one of the largest primary cortex areas and exists at the back side of the brain as the trailing edge of the occipital lobe. The primary cortex for auditory information is located in the temporal lobe behind the ears, where the right auditory cortex receives sound information from the left hemisphere and vice versa. The olfactory cortex for smell exists within the interior of the forward region of the brain known as the frontal lobe, and the gustatory cortex for taste is near it in the temporal lobe.
The motor cortex and somatosensory cortex make up different structural shapes and occupy different regions of the brain than do the primary cortex areas for the dominant senses. Control of movement and tactile sense is regulated by two wide bands of cortical tissue that stretch across the central region of the brain within the central sulcus and parietal lobe. The orbitofrontal cortex that is known to play a role in regulating emotions is located along a bottom, protected section of the frontal lobe of the brain.
Though the primary cortex regions of brain structure are vital to normal day-to-day living, they don't perform sensory tasks entirely on their own. The somatosensory cortex, for instance, that processes tactile information is directly mapped to sensory signals along the entire surface of the human body in a complex structure that is referred to as somatotopy. The auditory cortex relies on sound transmitted by the ears to convert it to language, and the olfactory bulb, or cortex region, depends upon 40,000,000 olfactory receptors in the human nose to detect odors.