In 1848, an explosion drives a steel tamping bar through the skull of a twenty-five-year-old railroad foreman named Phineas Gage, obliterating a portion of his frontal lobes. He recovers, and seems to possess all his earlier faculties, with one exception: The formerly mild-mannered Gage is now something of a hellion, an impulsive shit-starter. Ipso facto, the frontal lobes must play some function in regulating and restraining our more animalistic instincts.
In 1861, a French neurosurgeon named Pierre-Paul Broca announces that he has found the root of speech articulation in the brain. He bases his discovery on a patient of his, a man with damage to the left hemisphere of his inferior frontal lobe. The man comes to be known as "Monsieur Tan," because, though he can understand what people say, "tan" is the only syllable he is capable of pronouncing.
Thirteen years later, Carl Wernicke, a German neurologist, describes a patient with damage to his posterior left temporal lobe, a man who speaks fluently but completely nonsensically, unable to form a logical sentence or understand the sentences of others. If "Broca's area," as the damaged part of Monsieur Tan's brain came to be known, was responsible for speech articulation, then "Wernicke's area" must be responsible for language comprehension.
And so it goes. The broken illuminate the unbroken.
Edit, 5-25-11: There's been some interesting research on using brain stimulation to aid learning: essentially using tiny amounts of electricity to induce changes in rats' brains that makethem better learners. After the current is shut off, the rats' brains go back to normal but they keep their learned skills. We don't know what the specific trade-offs may be, but between this approach and approaches which could mimic developmental neuroplasticity triggers, we may have the basis for a very desirable form of cognitive enhancement.
Here's "Scienceblog" on the a theory on how the brain picks which of its neural networks to use for a new skill:
Edit, 7-28-11: Scientists have traced the recall of a specific memory and found it partially activates other memories from around the same time. Unsurprising, given it's common to experience memories as strongly linked, but still good science, and perhaps it supports the viewpoint that all memory is ultimately episodic in some real sense.
Researchers have long known that the brain links all kinds of new facts, related or not, when they are learned about the same time. Just as the taste of a cookie and tea can start a cascade of childhood memories, as in Proust, so a recalled bit of history homework can bring to mind a math problem — or a new dessert — from that same night.
For the first time, scientists have recorded traces in the brain of that kind of contextual memory, the ever-shifting kaleidoscope of thoughts and emotions that surrounds every piece of newly learned information. The recordings, taken from the brains of people awaiting surgery for epilepsy, suggest that new memories of even abstract facts — an Italian verb, for example — are encoded in a brain-cell firing sequence that also contains information about what else was happening during and just before the memory was formed, whether a tropical daydream or frustration with the Mets.
The new study suggests that memory is like a streaming video that is bookmarked, both consciously and subconsciously, by facts, scenes, characters and thoughts.
...“When you activate one memory, you are reactivating a little bit of what was happening around the time the memory was formed,” Dr. Kahana said[.]