Module 12 The Cerebral Cortex

LEARNING TARGETS

• 12-1 Describe the four lobes that make up the cerebral cortex and explain the functions of the motor cortex, somatosensory cortex, and association areas.
• 12-2 Analyze the notion that we really use only 10 percent of our brain.
• 12-3 Discuss how the brain adjusts to new experiences.
• 12-4 Discuss the brain’s ability to reorganize itself after damage, and explain neurogenesis.

Older brain networks sustain basic life functions and enable memory, emotions, and basic drives. Newer neural networks within the cerebrum—the two cerebral hemispheres contributing 85 percent of the brain’s weight—form specialized work teams that enable our perceiving, thinking, and speaking. Like other structures above the brainstem (including the thalamus, hippocampus, and amygdala), the cerebral hemispheres come as a pair. Covering those hemispheres, like bark on a tree, is the cerebral cortex, a thin surface layer of interconnected neural cells. In our brain’s evolutionary history, the cerebral cortex is a relative newcomer. It is your brain’s thinking crown, your body’s ultimate control and information-processing center.

cerebral [seh-REE-bruhl] cortex

the intricate fabric of interconnected neural cells covering the cerebral hemispheres; the body’s ultimate control and information-processing center.

As we move up the ladder of animal life, the cerebral cortex expands, tight genetic controls relax, and the organism’s adaptability increases. Frogs and other small-cortex amphibians operate extensively on preprogrammed genetic instructions. The larger cortex of mammals offers increased capacities for learning and thinking, enabling them to be more adaptable. What makes us distinctively human mostly arises from the complex functions of our cerebral cortex.

Check Your Understanding

Ask Yourself

• Does learning about our brain’s evolutionary history make you feel more connected to, or more separate from, other mammals and our distant ancestors?

Test Yourself

• Which area of the human brain is most similar to that of less complex animals? Which part of the human brain distinguishes us most from less complex animals?

Answers to the Test Yourself questions can be found in Appendix E at the end of the book.