Neural Mechanisms of Eye Movements and Attention
Our research elucidates the mechanisms that allow humans to
move their eyes to the right place at the right time. Rapid
and accurate eye movements are crucial for vision because
we have high visual acuity only in the center of our gaze
and we must continually shift our gaze to interpret or act
upon objects outside this limited area. Saccadic eye
movements are largely responsible for these gaze shifts,
and we typically make more than 200,000 saccades every day.
Dysfunctions of the saccadic system can have devastating
consequences for our ability to read, to drive, or even to
perform fairly simple visually-guided tasks.
Neural Control of Saccades
Natural visual scenes typically contain many different
potential objects of interest. Our research addresses the
fundamental question of how the saccadic system selects one
of these objects as the target of an eye movement. We study
this target selection process using visual search tasks in
which subjects scan a display to find a target embedded in
distractors while we monitor neural activity in various
regions of the brain.
Our experiments have shown that the Superior Colliculus, a
structure in the mid-brain, plays an essential role in
selecting the target of an impending movement. By
temporarily inactivating neurons in the Superior
Colliculus, we can simulate the consequences of damage to
this area of the brain and begin to understand how the
effects of such damage could be mitigated in patient
populations.
Eye Movements and Attention
Research has shown that we can shift attention to an object
without moving our eyes. Such shifts of attention perform a
function analogous to that of eye movements, as they can
improve perception of an object in the periphery. Our
current research in this area aims to clarify the working
relationship between attention and saccades, and to examine
the specific roles of areas in the frontal lobe and in the
brainstem in the control of attention.
