A Tasty Program at the Rubin

The lady has an extraordinary palate, a palate of incredible finesse. She picks up hot ingredients, touches them, and she thinks about this image on the plate. She has the most disciplined execution on a plate that we’ve ever seen. But the palate is where it’s just extraordinary. And honestly, I know chefs with Michelin stars that don’t have palates like hers.                           –Chef Gordon Ramsay, MasterChef judge

Christine Ha’s blindness didn’t stop her from defeating more than 30,000 home cooks to secure the coveted MasterChef title, a $250,000 cash prize, and a cookbook deal. Her extraordinary story caught the attention of the organizers of the Brainwave series at the Rubin Museum of Art in New York City, who invited her to talk to neuroscientist David Linden about the food-brain connection in a program entitled, “How Does a Blind Cook Cook?

ha-brainwave

Photo credit: Asya Danilova

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New Brain Briefs on the Senses

Do you know that emotions increase activity in the visual cortex, so “colors look more vivid and details stand out when we’re happy, angry, or frightened”?  Or that hair cells play a vital function in hearing and that as we get older the “progressive loss of hair cells means less acute hearing, particularly in higher frequencies”? How about that olfactory receptor cells are themselves neurons that are “on one end in direct contact with the external world and the other in direct contact with the brain”?  Have you ever wanted to learn more about how our senses function?

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The Circuitry of Vision

Colloquially, the eyes are the window to the soul. Biologically, they may be the key to enhancing scientific understanding of the brain’s neural circuits.

At an event co-sponsored by the German Center for Research and Innovation and the Max Planck Florida Institute, Joshua Sanes, a member of the Dana Alliance for Brain Initiative and professor at Harvard University, and David Fitzpatrick, scientific director and CEO of the Max Planck Florida Institute, explained their research into the circuitry of the retina and the visual cortex.

Their research brings into focus the roles genetics and environment play in shaping neural circuitry.

As Dr. Sanes explained, the retina is complicated but compact, making it “a playground for figuring out how circuits work.” Three layers of cells make up the retina: photoreceptors, which sense light; interneurons, which process information between the layers; and retinal ganglion cells, which respond to movement, orientation, color contrast, and edges. There are at least 50 types of interneurons and retinal ganglion cells, and only a few connect to each other, forming parallel pathways for communicating visual information.

Using a fluorescent protein, Sanes’ lab marked the gene Jam-B, which only appears in a small number of mouse retinal ganglion cells. They found that the dendrites of these cells all had the same orientation, and that the axons all pointed toward the center of the retina. They all respond to motion moving in the direction of their dendrites.

RetinaStained Jam-B RGC dendrites pointing in the same direction, with axons going toward the center of the retina. (Credit: In-Jung Kim and Joshua Sanes, 2008)

“It’s rare that you can determine function from structure,” said Sanes. But these cells—and at least nine other types of retinal ganglion cells now identified by scientists—are genetically hard-wired to respond to particular directions of motion.

In contrast, said Fitzpatrick, experience can shape the responses of cells and circuits in the visual cortex.

Using two-photon in vivo microscopy, an imaging technique that allows researchers to study brain activity in living animals, Fitzpatrick looked at direction-selectivity emergence in individual neurons in the ferret cortex. Ferrets are not born with direction-selective cortical cells—there is a critical window for their development soon after birth.

Fitzpatrick and his colleagues presented visually naïve ferrets with a motion stimulus while recording their neuronal activity. After eight to ten hours of training, direction signals correlating to the direction of the stimulus began to form. “Experience was driving circuit emergence,” said Fitzpatrick.

Some cortical cells do show a weak bias toward one direction over another when shown a bidirectional object; there may be some genetic-experience interaction at play. Still, no one yet knows why experience molds cortical cells, while genetics alone drives retinal cells. But clearly, the imaging techniques now available to neuroscientists—like two-photon microscopy and fluorescent proteins—will help answer these questions while unraveling the brain’s neural circuitry.

–Johanna Goldberg

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