The 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 mechanisms are related to visual perception. Recently, we have obtained behavioral and electrophysiological data indicating that there is functional overlap between the neural mechanisms for pursuit and saccades. The objective of this application is to investigate the nature and degree of this functional overlap In particular, we will determine how the rostral superior colliculus and one of its primary targets, the paramedian pontine reticular formation, participate in the control of pursuit, as well as saccades. This proposal tests two main hypotheses. First, that some neurons in the rostral superior colliculus encode the retinal locations of possible targets, rather than specific commands for eye movements. Second, that the decision to make a saccade or pursuit or no eye movement occurs downstream. The project will address the following three questions: (1) What types of information are encoded by neurons in the rostral superior colliculus that could be used to guide both pursuit and saccades? (2) Is activity in the rostral colliculus selective for the location of the target or the type of eye movement that the subject makes? (3) Could activity in the paramedian pontine reticular formation provide part of the command for pursuit or determine which type of eye movement is made? At the completion of this research, we expect to understand how activity in the rostral superior colliculus is related to the mechanisms of both target and eye movement selection, and to have a preliminary understanding of how activity in the paramedian pontine reticular formation contributes to the control of pursuit. These studies are a step toward understanding how the brain coordinates the components of voluntary movements and how it establishes and regulates the line between visual processing and movement selection. These studies will therefore help refine clinical descriptions of the oculomotor system that are used to diagnose eye movement disorders in humans.

Agency
National Institute of Health (NIH)
Institute
National Eye Institute (NEI)
Type
Research Project (R01)
Project #
5R01EY012212-04
Application #
6384747
Study Section
Visual Sciences B Study Section (VISB)
Program Officer
Hunter, Chyren
Project Start
1998-08-01
Project End
2003-07-31
Budget Start
2001-08-01
Budget End
2002-07-31
Support Year
4
Fiscal Year
2001
Total Cost
$351,918
Indirect Cost
Name
Salk Institute for Biological Studies
Department
Type
DUNS #
005436803
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
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
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; 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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