1997: Galletti


The Minerva Foundation named Italian scientist Claudio Galletti the winner of its 1997 Golden Brain Award for discoveries that helped to explain how the brain links seeing, knowing, and reaching.

The Berkeley-based foundation presents the Golden Brain Award each year to a researcher who has made a fundamental contribution to our knowledge of vision and the brain.

Galletti, professor of physiology at the University of Bologna, was honored for discovering two mechanisms in the brain that help us survive--one that enables us to have a stable perception of our visual environment and one that links vision and reaching.

He received the Golden Brain Award on Tuesday, October 28th, at a private dinner in New Orleans, where he was attending a meeting of the Society for Neuroscience.

Galletti works with macaque monkeys, whose visual system is very similar to that of humans. In his earlier research, he found that certain cells in the brain (called real position cells) keep track of the position of objects in space, regardless of where the eyes move. The part of the visual field from which these real position cells receive information (their receptive field) remains constant when the eyes move, in contrast to other known visual cells, whose receptive field moves with the direction of the gaze.

If, for example, we look directly at a lamp ahead of us and then move our glance to the left or right, the real position cells keep us aware of the lamp’s true location--that is, we perceive the lamp still in the same place in space, even though shifting our eyes will cause the lamp to appear at the edge, rather than the center, of our field of vision.

"Without this mechanism," said the late Elwin Marg, executive officer of the Minerva Foundation, "every time we moved our eyes, objects would appear to be moving. We couldn’t function. Galletti has helped to explain how this critical machinery works."

Galletti also found that the same region of the brain in which he discovered real position cells also links vision to reaching and grasping.

In this cortical visual region, he found cells related to arm movement. No such cells had previously been known to exist there. He concluded that this part of the brain "seems to be an interface between the visual world and the motor world."

Galletti has continued his research to prove that the arm-movement-related cells in this area (parietal cortex) use information coming from the motor centers of the brain to tell their neighboring visual cells what the arm is doing. He believes the interaction of these two kinds of cells enables us make the complex adjustments needed to reach successfully for objects.

"When you want to reach for a glass of water, for example," he said, "you thrust your arm towards the glass. To do that, you need the spatial coordinates of the glass. Real position cells could well provide this information. Moreover, while your arm is moving toward the glass, you can correct its position in space. To do this, you need visual information about where your arm is and where it is going, and you need information about the position of the glass in your visual field. This area of the brain can provide all the necessary visual information as well as somatosensory and somatomotor information about the position of your arm and the direction in which it is moving."

Galletti said the link he found between vision, reaching and grasping in the macaque could explain why humans with a lesion in the corresponding region of the brain are unable to reach for and grasp objects – a condition known as optic ataxia.