LAFAYETTE, La., Sept. 28, 1999 - Scientists have long known that humans have unusually large brains compared to apes, our closest primate relatives. But until now, evidence of differences in the internal structure of human and primate brains has been lacking.
In a groundbreaking study published today by the National Academy of Sciences, a team of scientists led by Dr. Todd Preuss of the University of Louisiana at Lafayette for the first time shines light on the unique "neural architecture" of the human brain. In research partially funded by the James S. McDonnell Foundation, Preuss and Drs. Huixin Qi and Jon Kaas of Vanderbilt University report differences in the brain "hardwiring" of humans, apes, and monkeys.
"This study provides the first well-documented case of a difference in the brain organization of humans and apes that isn't simply related to differences in the size or shape of the brain," said Dr. Daniel Povinelli, co-director of UL Lafayette's Institute of Cognitive Science.
The uniquely human feature discovered by Preuss's team involves neurons in the so-called "magnocellular" (or M) pathway of the primary visual cortex, which is specialized for analyzing rapidly changing stimuli. Preuss suggests that this finding could pave the way for better understanding of diseases like dyslexia.
"There's good evidence that dyslexia is accompanied by defects of the M pathway. Our understanding of this common disorder might be improved if our ideas about the human M pathway, which are currently based almost exclusively on studies of monkeys, were to take into account human specializations."
Preuss added: "Neuroscientists naturally focus on the similarities between humans and other animals in order to develop animal models of disease. And, there are many similarities between the brains of humans and other animals. But we need to study the differences, too, so we can begin to understand what's truly distinctive about the human brain and human mind."
Povinelli called Preuss's study an exciting advance for cognitive science. "If there are differences like this in the part of the brain that deals with seeing, just imagine what we're going to discover when we turn to brain regions involved in planning and reasoning."
Susan M. Fitzpatrick, program director for the James S. McDonnell Foundation, said the Foundation is "pleased to support truly groundbreaking research which requires us to think about the brain and evolution in startlingly, new ways."
Editor's Note: To read a copy of Dr. Preuss's study, please phone the press office of the National Academy of Sciences: 202-334-2138
Journal
Proceedings of the National Academy of Sciences