Dr. Sabine Kastner, a professor of neuroscience and psychology at Princeton University, is studying how the brain weeds out important information from every day scenes. Using functional magnetic resonance imaging (fMRI), Kastner is able to peek inside the brain and see what areas are active when a person sees a face, place, or object. "Mysteries of the Brain" is produced by NBC Learn in partnership with the National Science Foundation.
Mysteries of the Brain - Perceiving Brain
TOM COSTELLO, reporting:
Every day, we are bombarded by sights, smells, tastes, textures, and sounds-- senses that allow humans and animals alike to perceive the world around us and to survive. With all these sensations coming in, scientists are trying to solve how the brain is able to process and organize them. For some animals, including humans, the answer may lie in one of our most complex senses: vision.
SABINE KASTNER (Princeton University): One third of the primate brain is dedicated to vision. It is a huge real estate.
COSTELLO: Dr. Sabine Kastner is a neuroscientist at Princeton University who is funded by the National Science Foundation. She and her team are studying how the visual system in the brain is able to weed out important information from a busy scene in order to perform even simple tasks, like crossing the street.
KASTNER: And I was thinking to myself, while I was crossing the street, I was looking for cars, what is known about what we do, what's going on in the brain when we do just that?
COSTELLO: In all animals, vision begins with the eyes. The retina acts like a camera's memory card and captures an image of what it is seeing. The image is then transmitted as electrical impulses through a bundle of nerve fibers to the thalamus, the brain's switchboard. From there, these impulses travel to the visual regions in the cortex, are interpreted, and then sent to the parts of the brain that control behavior. So whether it is a person looking for cars or a hawk searching for prey, they will be able to respond quickly. But how does the brain know which parts of a scene are important and which are not?
KASTNER: A fundamental problem that we encounter in vision is that there are always lots and lots of things around us.
COSTELLO: To test how animals' brains make sense of crowded visual scenes, Kastner and her team designed experiments that use functional magnetic resonance imaging, or fMRI, to peek inside the human brain.
KASTNER: So we just took two thousand scenes, they were all outdoor, street scenes, basically. And we showed them to human subjects in our scanner.
COSTELLO: The machine sends back three-dimensional images of the brain in real time, showing the regions of the brain that are active when the subject sees a place, object, or person. Another experiment utilizing fMRI studies how the brain recognizes faces and facial cues, an ability that could help an animal identify friend or foe.
KASTNER: Nonhuman primates can do these sort of interpretations just as we can. There's a big difference if a bigger monkey is angry and wants to come after you in the wild.
COSTELLO: The results from Kastner's experiments point to the crucial role played by complex networks of cells, called neurons, that transmit information throughout the brain.
KASTNER: Most of the operations that the brain is performing involves networks. That means that there are many, many areas involved that often somehow span the entire brain.
COSTELLO: To help neuroscientists like Kastner better understand these networks, they are beginning to collaborate with mathematicians, computer scientists, and physical scientists to create theoretical and computational models of these complex networks. These collaborations will help scientists understand how these biological systems play key roles in perception.
KASTNER: And this is what mathematicians, applied mathematicians, physicists, statisticians, computer scientists really have the background to do. So they can give us models of what these computations in these nodes may be.
COSTELLO: Understanding the brain's networks will help scientists understand how animals perceive the world around them, and could even contribute to the development of new technologies, for instance, more advanced facial recognition technology. This also could lead to better treatments for brain disorders, like ADHD and schizophrenia. Although the brain's visual system is riddled with mystery, dedicated neuroscientists like Kastner are providing a clearer picture of all that the brain can do.
One of the amazing complexities of life is an organism's ability to recognize and react to its surroundings. This trait of awareness exists in the smallest single-celled organism as well as in the most complex of creatures — that is, Homo sapiens, like you and me.
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