|Grant Number: 2R01EY006860-21
Project Title: Studies of the Oculomotor Systems
PI Information: SENIOR SCIENTIST EDWARD L. KELLER,
Abstract: DESCRIPTION (provided by applicant):
reactive saccades, directing the eyes to a target most
appropriate in a given situation requires substantial cognitive
processing. Sensory cues present in the environment need to be
evaluated in terms of symbolic meanings associated with them.
These then have to be translated so that the saccade goal is
chosen among alternatives available at the moment.
neural underpinnings of these complex processes is essential for
advancing our knowledge of how the brain makes choices and how
cognitive information is utilized in oculomotor behavior.
Equally important, this knowledge will provide a better
understanding such abnormal behaviors as oculomotor apraxia in
which reflexive visually-guided saccades are preserved while
saccades prompted by verbal commands are impaired and frontal
lobe dysfunction in which the inability to make choice decisions
is an important feature.
Both the latter disorders are of public
health concern. In this project, we will collect neural data
while saccades are generated as a choice response based on the
pre-trained associations between color and spatial location:
Animals will attend to visual stimuli of different colors
delivered at the fovea and respond with an eye movement to a
unique location associated with each color.
designed to achieve the following specific aims: 1) To
characterize neural signals in the superior colliculus (SC) and
the cortical frontal eye fields (FEF) related to saccadic choice
responses by recording from single neurons. Whether these
signals are indeed necessary for saccadic choice responses will
be determined by making reversible chemical lesions in the 2
structures. More specifically, by selectively inactivating the
foveal portion of the FEF, we will test the hypothesis that the
FEF is the place where sensory cue information given at the
fovea is translated into the activation of neurons representing
a target in the periphery.
2) To identify the source of
cue-driven signals observed in the caudal SC. Given the fact
that the FEF has abundant connections to this region, we will
test the hypothesis that the FEF is the source of cognitive
signals recorded in the SC. Reversible lesions will be made in
FEF as a SC neuron with cue-driven signals is being recorded.
Changes in the activation of the SC during choice response would
support this hypothesis.
3) To examine the temporal relationship
between the activities in pairs of FEF cells that code for the
target location and others that code for non-target locations,
while a choice decision is being made. This data will help to
differentiate between 2 current models that attempt to explain
the neural mechanisms underlying choice response.
neural information processing, neurophysiology, neuroregulation,
saccade, superior colliculus, visual pathway, visual perception
brain electrical activity, extraocular muscle, motion
perception, neural inhibition, neural initiation, neuroanatomy,
sensorimotor system, tegmentum, visual feedback, visual field,
Macaca mulatta, behavioral /social science research tag,
computer data analysis, electrophysiology
Institution: SMITH-KETTLEWELL EYE RESEARCH INSTITUTE
SAN FRANCISCO, CA 94115
Fiscal Year: 2006
Project Start: 01-MAY-1986
Project End: 31-MAR-2009
ICD: NATIONAL EYE INSTITUTE
J Neurophysiol 91: 890-900, 2004. First published October 15,
Properties of Saccadic Responses in Monkey When Multiple
Competing Visual Stimuli Are Present
Kuniharu Arai, Robert M. McPeek and Edward L. Keller
The Smith-Kettlewell Eye Research Institute, San Francisco,
Submitted 20 August 2003; accepted in final form 10 October 2003
Two male rhesus monkeys (Macaca mulatta) weighing between 4
and 7 kg were used in this study. All experimental protocols
were approved by the Institutional Animal Care and Use Committee
at the California Pacific Medical Center and complied with the
guidelines of the Public Health Service policy on Humane Care
and Use of Laboratory Animals.
A scleral eye coil and a head-holder system were implanted under
isoflurane anesthesia and aseptic surgical conditions.
Anesthesia was induced with an intramuscular injection of
ketamine. Heart rate, blood pressure, respiratory rate, and body
temperature were monitored for the duration of the surgery. A
coil made of four turns of Teflon-coated stainless steel wire
was implanted under the conjunctiva of one eye using the
procedure described by Fuchs and Robinson (1966 ), as modified
by Judge et al. (1980 ). At the completion of the surgery,
animals were returned to their home cages. Antibiotics (Cefazolin)
and analgesics (Buprenex) were administered as needed during the
recovery period under the direction of a veterinarian.
Testing was performed in a dimly illuminated room. Data
collection and storage were controlled by a custom real-time
program running on a PC. Eye position and velocity were sampled
at 1 kHz and digitally stored on disc. A Macintosh computer,
which was interfaced with the PC, generated the visual displays
using software constructed using the Video Toolbox library (Pelli
1997 ). Visual stimuli were presented on a 29-inch color cathode
ray tube (Viewsonic GA29) in synchronization with the monitor's
vertical refresh. The monitor had a spatial resolution of 800 by
600 pixels and a noninterlaced refresh rate of 75 Hz. The
monitor was positioned 33 cm in front of the monkey and allowed
stimuli to be presented in a field of view of approximately ±32°
along the horizontal meridian and ±30° along the vertical
The monkeys were seated in a primate chair with their heads
restrained for the duration of the testing sessions. They
executed behavioral tasks for liquid reward and were allowed to
work to satiation. Records of each animal's weight and health
status were kept, and supplemental water was given as necessary.
The animals typically worked for 5 days and were allowed
controlled access to water on weekends.