The cerebral cortex is gray matter that acts as the outer layer of neural tissue that covers the cerebrum (most anterior part of the brain) in humans and other mammals. It is around 2-4 millimeters thick in humans, and contains around 70% of the brain's 100 billion neurons. It is split into a left hemisphere (controls the right side of the body) and right hemisphere (controls the left side of the body), and into four different lobes: the parietal lobe, frontal lobe, temporal lobe, and occipital lobe. The cerebral cortex plays a large role in memory, attention, perception, awareness, thought, language, and consciousness.
As each of the lobes (and the cortexes located in each lobe) hold different functions, damage to the cerebral cortex can cause many different problems, depending on which part of the cerebral cortex was injured.
The frontal lobe is involved in personality, emotions, decision making, speech, body movement, and more. It contains the pre-frontal cortex, which plays a part in processing short/long term memories. The left frontal lobe is mostly involved in controlling language related functions, while the right frontal lobe is mostly involved in non-verbal functions. Frontal lobe damage has been associated with poor control of facial expression, loss of fine movements and arm strength, and interference with attention and memory. Frontal lobe injuries also commonly cause dramatic changes in social and sexual behavior.
The parietal lobe is involved in integrating sensory information; it interprets speech, controls sense of touch and pain, and is in charge of spatial and visual perception. It contains the Sensory Cortex, which receives information from the spinal cord in regards to movement and the position of various body parts, and the Motor Cortex, which helps the brain control movement. Damage to the Parietal Lobe can cause one to experience abnormalities in body image and spatial relations. Damage to the left parietal lobe can often times cause "Gerstmann's Syndrome," which can lead one to experience left-right confusion, writing difficulties (agraphia), and difficulties with mathematics (acalculia). It can also result in language disorders (aphasia) and inhibit one's ability to perceive objects (agnosia). Contrastingly, damage to the right parietal lobe can cause difficulty in self-care, such as dressing and washing oneself (contralateral neglect), making things (constructional apraxia), and drawing. Damage to both sides of the Parietal Lobe (Bi-lateral damage) can result in "Balint's Syndrome," a disorder that causes visual attention and motor problems. Symptoms include the inability to control gaze (ocular apraxia), a deficit in integrating components of a visual scene (simultanagnosia), and trouble reaching for physical objects without visual guidance (optic ataxia).
The temporal lobe is involved in understanding language, memory, and hearing. It contains Wernicke's area, which is thought to help the body formulate and understand speech. Temporal lobe injuries can cause an array of problems relating to visual and auditory perception. Damage to the left temporal lobe can result in a decreased recall of verbal and visual content. Damage to the right temporal lobe can result in a decline in artistic ability, such as a decline in musical and drawing skills.
The occipital lobe interprets vision (color, light, movement). It contains Broca's area, which controls the facial neurons and helps with the understanding of speech and language. Disorders of the occipital lobe can cause visual hallucinations and illusions. It can also cause the affected person to experience an abnormality in object color, and visual and writing impairments.
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