ANATOMY [ DIFFERENT PARTS DIFFERENT RESPONSIBILITIES ( THE AMAZING BRAIN ) ]
THE FRONTAL LOBE
A portion of the frontal lobe of each hemisphere called the precentral gyrus controls the body’s movements. Oddly, each hemisphere moves the opposite side of the body, as if the brain’s wiring some-how became crossed. Hence, the movements of the right hand and right foot, as well as the rightward gaze of both eyes, are governed by the left side of the brain. This phenomenon has been observed for centuries. Hippocrates noted that a sword injury to one side of the head impaired movement on the body’s opposite side. And while observing combat wounds during the Prusso-Danish War of 1864, German doctor Gustav Theodor Fritsch noted that if he touched the cerebral cortex as he dressed a head wound, the patient twitched on the opposite side of his body. If one hemisphere’s precentral gyrus is destroyed-during a stroke, for instance-paralysis will result in half the body.
In front of the precentral gyrus lie the premotor cortex and the prefrontal fibers. The former organizes the body’s complex physical movements, whereas the latter inhibit actions. Inhibition is useful in a variety of social settings, such as preventing shouting in a quiet movie theater.
THE BRAIN NEEDS regular exercise if its neurons area to remain sharp. Repetition of newly learned tasks helps make those new connections stronger. Without stimulation, dendrites recede and the brain settles into simpler patterns of operation. Neurologist Robert Friedland has shown that posing new challenges to the brain can help in the defense against Alzheimer’s disease.
Perhaps not surprisingly, “Use it or lose it” appears TO be true not on Iy of mental exercise but also of physical stimulation of the brain. The brain is like other organs and works better when the body is healthy. Exercising the body regularly appears to help ward off Alzheimer’s disease, as do reducing body weight, lowering blood pressure, and eating a more healthful diet. General exercise that builds up cardiovascular endurance improves blood flow to the brain. A healthy heart usually is linked to a healthy brain, especially in the brain’s “executive function, ” which is crucial to a slew of mental tasks.
A combination of physical exercise and mental gymnastics protects the brain against deterioration with age. To spur on the brain to make new neuronal connections and protect the ones it has, there are a number of activities to try, such as:
- Learning a new language .
- Listening to classical music.
- Solving mental puzzles and games, like crossword puzzles and Sudoku .
- Eating a healthful diet.
- Walking, jogging, or cycling regularly to promote cardiovascular health .
- Maintaining a healthy weight.
PARIETAL LOBE AND TEMPORAL LOBE
In the parietal lobe lies the somatosensory cortex, which takes in stimulations of touch and other sensations. While lower parts of the brain register pain and pressure, the sensory cortex helps localize such feelings. Damage to the sensory cortex may result in confusion about which part of the body may be registering pain.
The temporal lobe is home to the functions of hearing and appreciation of music and to some aspects of memory. Self-experience also resides in this lobe. Electrical stimulation of the temporal lobe may dredge up intense feelings from the memory-the experience of reliving the past, known as deja vu-or do just the opposite, causing familiar people and objects to become unrecognizable.
At its base, the temporal lobe connects with the limbic system, a series of brain structures also known as the animal brain. This system allows humans to experience intense emotions such as anger and fear as well as react to these feelings.
Behind the temporal lobe, near the rear of the head, lies the brain’s visual center in the occipital lobe. Far from the eyeballs, which take in visual information, this portion of the cerebral cortex processes electrical impulses that begin with light waves striking the retina. Wounds to the back of the head injuring the visual cortex can sometImes cause blindness.