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Brandeis University's Community Newspaper — Waltham, Mass.

Schiller honored for Pepose science award

Published: March 18, 2011
Section: News

The university honored Peter Schiller, a professor in Medical Engineering and Medical Physics at MIT, for winning Brandeis’ Jay Pepose ’75 Award in Vision Sciences established in 2009.

The award is funded through a $1 million grant established by Brandeis graduates Jay Pepose ’75 and Susan K. Feigenbaum ’74. After winning the award, Schiller delivered a lecture titled “Parallel Information Processing Channels Created in the Retina” on Monday in a Gerstenzang auditorium.

Schiller’s research focuses on vision and understanding processing channels.

“There are probably now more than 50 different laboratories in the world,” as Maunsell explained, “which can trace their scientific heritage back to Peter.” Schiller also was elected to the National Academy of Science in 2007.

Schiller began by discussing midget and parasol systems originating in the retina. He spoke about the ganglion cells in the retina which are broken down into midget ganglion cells, with a “relatively small cell body” connected through arbors with the photoreceptors, and the larger parasol ganglion cells with more expansive arbor connections.

After discussing the basics of midget and parasol cells, Schiller explained the various discoveries of the cells during the past century.

One discovery was that he receptive fields of the parasol cells are three times that of the midget cells. Also the midget and parasol receptor cells can be divided into a center of the receptive field and a surrounding area.

To illustrate the function of the cells, Schiller explained that the cells are inhibitory, meaning that they do not actually measure light but rather just measure differences in light.

Schiller also discussed the functions the different midget versus parasol cells perform, and he explained tests performed with monkeys where he discovered some of these functions.

For example, discriminating between different colors is owed to the midget system, as when a monkey’s midget system was inhibited he had difficulty seeing color.

The midget system is also responsible for texture and pattern discrimination. However, the parasol system is responsible for perceiving flickering lights, and also plays a major role in motion perception. They do however share brightness, as both are responsible for that part of visual perception.

Following his discussion of the midget and parasol ganglion cells, Schiller then went on to discuss his second part of the presentation, the on-and-off-channels. According to Schiller, the on-cells respond to the appearance of something while the off cells respond to the disappearance of something.

Schiller displayed various ideas as to why the on-and-off-systems exist. Through use of a chemical abbreviated as APB, he tested various functions that the on and off cells could fill. APB, when injected into the eye of a monkey could disable the on-cells while simultaneously allowing the off cells to function normally. Schiller questioned some of the hypotheses which have arisen concerning the evolution of the on-and-off-systems.

After probing various ideas, Schiller concluded, as he did in his research, that the on-and-off-channels evolved in order to process light increment and light decrement. For example, the on-cell would respond to a light spot but not a dark spot while the off-cell would respond to a dark spot but not a light spot.

He used the real-world example of reading to explain the on-and-off channels. For example, reading the traditional black letters in a book involves using the off-systems, while reading lighter letters on a darker background, the on-systems.