Our long-range goal is to understand how the neural mechanisms for pursuit and saccadic eye movements operate in health and in various human disease states and how these motor mechanisms are related to higher-level functions. Although pursuit and saccades have long been viewed as distinct motor systems, recent work from our lab and others has shown that certain crucial processing stages are shared. This shared processing likely ensures that pursuit and saccades are properly coordinated with each other and with visual perception and cognition during normal behavior. The objective of this application is to increase our understanding of this functional overlap. In particular, we will examine the role of the frontal eye fields (FEF) in target selection for pursuit and visual judgments about visual motion, and compare the role of the FEF to that of the superior colliculus (SC). Our primary hypothesis is that some of the neural activity in the FEF is related to general estimates of target position and velocity that are agnostic about the eye motor output;consequently, these signals would be expected to support visual judgments as well as target selection for pursuit and saccades. The project will address the following three questions: (1) Does the SC contribute to the process of visual discrimination in addition to its role in target selection? (2) Does the FEF play a role in target selection for pursuit, and if so, how does this role compare to its contributions to visual discrimination? (3) Does the FEF contribute to the visual judgments involving motion? At the completion of this research, we expect to understand how activity in the SC and FEF is related to the mechanisms of target selection for pursuit, as well as saccades, and to have clarified the relationship between target and visual selection involving motion. The relevance of this research to public health. These studies are an important step toward understanding how the brain coordinates the components of voluntary movements and how it establishes and regulates the link between visual processing and motor control. These studies will therefore help refine clinical descriptions of the oculomotor system that are used to diagnose eye movement disorders in humans. Understanding how these systems interact will also help us understand how and why these circuits malfunction in a variety of developmental disorders.

Agency
National Institute of Health (NIH)
Institute
National Eye Institute (NEI)
Type
Research Project (R01)
Project #
3R01EY012212-12S1
Application #
8005869
Study Section
Central Visual Processing Study Section (CVP)
Program Officer
Araj, Houmam H
Project Start
1998-08-01
Project End
2011-07-31
Budget Start
2009-08-01
Budget End
2010-07-31
Support Year
12
Fiscal Year
2010
Total Cost
$218,183
Indirect Cost
Name
Salk Institute for Biological Studies
Department
Type
DUNS #
078731668
City
La Jolla
State
CA
Country
United States
Zip Code
92037
Hafed, Ziad M; Lovejoy, Lee P; Krauzlis, Richard J (2013) Superior colliculus inactivation alters the relationship between covert visual attention and microsaccades. Eur J Neurosci 37:1169-81
Hafed, Ziad M; Krauzlis, Richard J (2012) Similarity of superior colliculus involvement in microsaccade and saccade generation. J Neurophysiol 107:1904-16
Krauzlis, Richard J; Dill, Natalie; Fowler, Garth A (2012) Dissociation of pursuit target selection from saccade execution. Vision Res 74:72-9
Goffart, Laurent; Hafed, Ziad M; Krauzlis, Richard J (2012) Visual fixation as equilibrium: evidence from superior colliculus inactivation. J Neurosci 32:10627-36
Mahaffy, Shaun; Krauzlis, Richard J (2011) Neural activity in the frontal pursuit area does not underlie pursuit target selection. Vision Res 51:853-66
Hafed, Ziad M; Lovejoy, Lee P; Krauzlis, Richard J (2011) Modulation of microsaccades in monkey during a covert visual attention task. J Neurosci 31:15219-30
Mahaffy, Shaun; Krauzlis, Richard J (2011) Inactivation and stimulation of the frontal pursuit area change pursuit metrics without affecting pursuit target selection. J Neurophysiol 106:347-60
Nummela, Samuel U; Krauzlis, Richard J (2011) Superior colliculus inactivation alters the weighted integration of visual stimuli. J Neurosci 31:8059-66
Hafed, Ziad M; Krauzlis, Richard J (2010) Microsaccadic suppression of visual bursts in the primate superior colliculus. J Neurosci 30:9542-7
Nummela, Samuel U; Krauzlis, Richard J (2010) Inactivation of primate superior colliculus biases target choice for smooth pursuit, saccades, and button press responses. J Neurophysiol 104:1538-48

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