Question 23.16

Q: Well, do we? Besides being just plain silly, this pervasive myth is completely false. But it prompts some reasonable questions. Read on.

Question 23.17

Q: How can we measure brain activity? Brain imaging technologies capture pictures of the brain as it functions, revealing activity patterns, based on increased metabolism, in the different regions of the brain. One technique is called fMRI scanning (functional magnetic resonance imaging). In an fMRI scan, a giant magnet detects the relative amounts of oxygenated blood and deoxygenated blood in various parts of the brain. When parts of the brain are active, more blood flows to them and the sensitive magnet can pick up the change.

Question 23.18

Q: So what do these scans show? Do we use some parts of the brain more than others? Do mental tasks or physical sensations require the use of a specific part of the brain? Some recent findings include these.

Seeing your favorite foods activates brain reward centers. Subjects seeing images of their favorite foods show increased brain activity in the pleasure centers of the forebrain. And recovering drug addicts have a similar response to images of a syringe (or even an anti-drug advertisement), often prompting them to relapse. Both cases underscore the power of advertising.

Altruistic behavior activates reward centers. When playing a game called “Prisoner’s Dilemma,” in which people gain rewards based on their decisions to cooperate or act selfishly, brain activity in the forebrain’s reward center is increased when a player chooses to cooperate. This may indicate that our brains are built to produce a physiological “prodding” toward kindness in certain situations.

People with Alzheimer’s disease exhibit significantly reduced brain activity. When compared with healthy individuals of the same age, patients with Alzheimer’s show decreased activity throughout the parts of the brain associated with thinking and understanding, but normal activity in the areas active in movement and sensory perception.

Language tasks are localized in different parts of the brain. Language uses very different parts of the cerebral cortex, depending on whether someone is hearing, speaking, or reading. Among bilingual people, their second language is stored in a slightly different part of the brain if they acquired it past a certain age.

Question 23.19

Q: So how much of our brains are we using? For any particular task, not all regions of the brain are called into action, but over the course of a day, all of your neurons are used.