Two Brains in One Skull
The cerebrum is split into two hemispheres joined by the corpus callosum, a band of 200 million nerve fibers. Each hemisphere exhibits contralateral control, meaning it controls the opposite side of the body.
While connected, the hemispheres are lateralized for different tasks. In most people, the left hemisphere dominates language, housing Broca's area for speech and Wernicke's area for comprehension. The right hemisphere specializes in spatial processing, face recognition, and emotional perception.
Split-Brain Insights
Evidence for lateralization comes from split-brain patients whose corpus callosum was severed to control epilepsy. With the bridge cut, the hemispheres cannot share information directly.
| Function / Test | Left Hemisphere | Right Hemisphere |
|---|---|---|
| Visual Input | Right visual field | Left visual field |
| Naming Object | Can name aloud | Cannot name (no speech) |
| Manual Task | Right hand | Left hand picks it |
Common pitfall: The myth of left-brained versus right-brained people. Lateralization means certain functions lean to one side; healthy brains use both sides for everything.