Answer to Question 1
Postmortem studies and brain dissections have been done for centuries. Even in the twenty-first century, researchers often use dissection to study the relation between the brain and behavior. In the ideal case, studies start during the lifetime of a person. Researchers observe and document the behavior of people who show signs of brain damage while they are alive. Later, after the patients die, the researchers examine the patients' brains for lesionsareas where body tissue has been damaged, such as from injury or disease. Then the researchers infer that the lesioned locations may be related to the behavior that was affected. The case of Phineas Gage was explored through these methods.
Answer to Question 2
An ischemic stroke usually occurs when a buildup of fatty tissue occurs in blood vessels over a period of years, and a piece of this tissue breaks off and gets lodged in arteries of the brain. Ischemic strokes can be treated by clot-busting drugs. The second kind of stroke, a hemorrhagic stroke, occurs when a blood vessel in the brain suddenly breaks. Blood then spills into sur- rounding tissue. As the blood spills over, brain cells in the affected areas begin to die. This death is either from the lack of oxygen and nutrients or from the rupture of the vessel and the sudden spilling of blood. The prognosis for stroke victims depends on the type and severity of damage. Symptoms of stroke appear immediately on the occurrence of stroke.
The magnetic field of Uranus as observed by Voyager 2 in 1986. S and N are magnetic south and north
View of the bottom surface of the human brain.
The comparative brain sizes of different species
Measles rash. (© Lowell Georgia/Science Source/Photo Researchers, Inc.)
Decimal Values as They Relate to the Location of the Decimal Point
Changes that take place in the brain across the lifespan