Page Tools

 

Scientific Report


Scientific Report

Download the Scientific Report [7.5 MB]

View the entry for
Thomas D. Albright

 

Thomas D. Albright

Thomas D. Albright

Professor and Director
Vision Center Laboratory

"Light reflected from objects in the environment projects onto the retinal surface, resulting in intricate and dynamic patterns of brightness and color. Our goal has been to understand the neuronal structures and events that underlie visual perceptual experience, and its contributions to knowledge, behavior, and consciousness."

"It should come as no surprise that what you see is not determined solely by the patterns of light that fall upon your retinae. Indeed, that visual perception is more than meets the eye has been understood for centuries, and there are several extra-retinal factors known to interact with the incoming sensory data to yield perceptual experience. Perhaps foremost among these factors is information learned from prior encounters with the visual world—our memories—which enables us to infer the cause, category, meaning, utility, and value of retinal images.

But how does perceptual inference occur, and what are the underlying biological structures and events? Viewed in the context of a hierarchy of visual processing stages, prior knowledge of the visual world is believed to manifest itself as "top-down" neuronal signals that influence the processing of "bottom-up" sensory information arriving from the retina. In recent experiments, Albright and his team addressed the interactions between top-down and bottom-up signals.

In one set of studies, they explored the neuronal changes that parallel the acquisition of long-term memories of associations between visual stimuli, such as between a knife and a fork, or a train and its track. Such learning, they discovered, results from the strengthening of functional connections between neurons that represent the associated objects. In a second set of experiments, the researchers identified neuronal events that correspond to pictorial recall of visual memories. These results shed new light on "the mind's eye" and offer an objective approach to the phenomenon of subjective visual imagery. Finally, they uncovered a specific neuronal process by which visual pictorial recall serves to augment sensory data with "likely" interpretations, in order to overcome the ever-present noise, ambiguity, and incompleteness of the retinal image.

Taken together, the results of these experiments call for a significant shift in the way we think about the neuronal processing of sensory information, and they suggest that specific neuronal processes underlie common sensorylike experiences, such as visual imagery, dreaming, and hallucinations.

Lab Photo

Left to right: Ricardo Gil da Costa, Hulusi Kafaligonul, Micah Richert, Bryan Nielsen, Margaret Mitchell, Lee Campbell, Tom Albright, Johanna Jacob, Vivian Ciaramitaro, Dinh Diep, Gene Stoner, Justin Klein, Chris Hiestand, Jorge Aldana

Print version -
Thomas D. Albright

Faculty

Thomas D. Albright

Thomas D. Albright

Professor and Director
Vision Center Laboratory

Research in our laboratory focuses on the neural structures and events underlying the perception of motion, form, and color. Recent studies of the primate cerebral cortex have unveiled the existence of multiple areas devoted to the processing of visual information. Richly interconnected collections of these areas constitute functional subsystems for the detection, analysis, and interpretation of specific types of visual information. Through an integrative approach, which combines neurophysiological and psychophysical techniques, as well as computational modeling of neural networks, we are beginning to illuminate the mechanics of information processing in these high-level visual areas and to define their unique contributions to visual perception and visually guided behavior.

Education

Awards and Honors

Selected Publications

Links

Salk News Releases