Study: Internal Brain Activity Defines Perception

Nov. 03, 2004 — -- What is real and what is imagined? To try and answer that question, scientists monitored the brains of ferrets as the animals were forced to watch clips of "The Matrix."

The connection may not be so obvious, but the researchers worked from the assumption that ferret brains resemble human brains -- at least at a basic level. Scientists generally agree that you can see the rudiments of humans in mammals like ferrets. Then the team got inside the ferrets' heads.

The researchers at the University of Rochester in New York wired the brains of ferrets as the animals watched the mind-bending 1999 movie, as well as when they watched TV static and when they sat in complete darkness. The lead researcher, Michael Weliky, says the study demonstrated a lesson that Keanu Reeves' character, Neo, learned in the first Matrix movie -- that reality is more than what meets the eye.

"When we look at an object, 80 percent of what we see is internally driven while only 20 percent has to do with the real thing," said Weliky, who is an assistant professor of brain and cognitive science. "The big question is, what is going on internally to create that picture?"

For the study, which appeared in a recent issue of the journal "Nature," Weliky and his colleagues implanted extremely fine electrodes into the visual cortex of ferrets. Some of the subjects were young and had just opened their eyes, others were slightly more mature animals and a third group was made up of adults. He then compared the brain activity among the three groups in darkness and as they watched the movie and the TV static.

He found that while the young ferrets showed almost no brain patterns that correlated with the different visual inputs, the adult ferrets' brains were teeming with orderly activity -- even as they sat in the dark.

When the adult animals saw the movie or the TV static, their brain activity increased by 20 percent and reflected the images they saw. Inside the minds of the young ferrets, meanwhile, there was activity, but it did not change or reflect according to whether it was in darkness, watching static or the sci-fi film classic.