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Celebrating Science and Engineering Breakthroughs IV

03/29/2011 3:30 PM Kresge
Katrin Wehrheim, Associate Professor of Mathematics, MIT; Sallie Chisholm, Lee and Geraldine Martin Professor of Environmental Studies and Professor of Biology, MIT; Nancy Kanwisher, '80, PhD '86, Professor of Brain and Cognitive Sciences, MIT

Description: The wind"up session of this multi"part symposium on women at MIT brings together brains and brine -- two researchers' pioneering work in neuroscience and ocean microbes.

In 1985, Sallie (Penny) Chisholm discovered Prochlorococcus, a "tiny, round, green thing that's not so beautiful but extraordinary." Lined up, 100 of these sub"micron size phytoplankton come to the width of a human hair, and they turn out to be the most abundant photosynthetic cell on the planet. There are so many Prochlorococcus distributed through global oceans that their accumulated weight would amount to one billion people. Most important, life as we know it would not be possible without these (and other) photosynthetic ocean creatures, which produce a large share of the planet's oxygen.

Chisholm has spent more than two decades devoted to in"depth study of Prochlorococcus, which even as a single species presents many "ecotypes." Some fare better in great depths, far from the sun, others closer to the surface. Research has verified 12 genetically different strains of Prochlorococcus occupying different ocean niches _ and given that there are 1027 cells in the wild, many more genomes are literally floating around. Chisholm ultimately wants to understand why certain types of Prochlorococcus appear in particular ecosystems, and not in others. For instance, Prochlorococcus follow the Gulf Stream, but "disappear near Massachusetts." With faster gene sequencing, Chisholm and colleagues have been sampling seawater from around the world for Prochlorococcus, hoping to understand better the reasons for their diversity, and how they fit into the larger physical and chemical systems of the oceans. Nancy Kanwisher approaches fundamental questions involving the nature of the human mind using functional Magnetic Resonance Imaging (fMRI), which enables investigation of both structure and function of the brain. In particular, Kanwisher has been exploring whether the brain features regions specialized for specific purposes. Her studies have turned up several such areas: the fusiform face area of the brain, responsible only for face recognition; the parahippocampal place area, a region that responds to images of places or scenes; and the "third and most disreputable region," the extrastriate body area, which responds to pictures of bodies, body parts _ whether stick figures or silhouettes.

These regions are found in the architecture of all normal human brains, Kanwisher says, and their existence raises additional questions that she and other researchers are pursuing. For instance, to learn when these areas become wired in the brain, Kanwisher scanned children. She learned that kids as young as five years showed the same face recognition brain activity as adults. There is evidence "implicating genes" in face recognition. But there is a role for experience as well. Although there is a brain region that responds strongly to visual words and letter strings, the "selectivity of the region" depends on an individual's history (such as familiarity with written characters from specific languages). Kanwisher concludes that while there are some "highly specialized bits" of the mind/brain made up of specialized components, "these may be relatively rare, and there is probably lots of general purpose machinery."

About the Speaker(s): From 2007 to 2010, Katrin Wehrheim served as assistant professor of math at MIT. She received the B.S. equiv. in mathematics and physics from the University of Hamburg in 1995, and the Diploma in physics from Imperial College in 1996. She completed the Ph.D. in mathematics at ETH Z orich in 2002. Wehrheim's thesis was awarded the ETH Medal. She continued at ETH Z orich as a postdoctoral fellow, 2002"03, before going to Princeton University as instructor, 2003"04. She was a member of Institute of Advanced Studies, 2004"06 and fellow at Princeton, 2005"06.

Wehrheim's research interests include problems in gauge theory and symplectic topology and PDEs, in particular the relations of gauge theoretic and symplectic Floer theories.

Host(s): Office of the President, MIT150 Inventional Wisdom

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